Ortho MCQs: Hip, Knee, Spine & Trauma - Part 13

Question 1

Figure 11 shows the lateral radiograph of a 16-year-old boy who has been unable to participate in sports activities because of pain in the anterior aspect of the knee. He states that the pain is aching in nature and is located in the region of the tibial tuberosity. He denies having joint effusion or symptoms of instability. Management should consist of

Explanation

DISCUSSION: The prognosis for most patients with Osgood-Schlatter disease is good. When the secondary ossification center unites with the main body of the tibial tubercle, the patellar tendon has a more rigid anchor, and heterotopic ossification and its associated reaction often become quiescent. However, even after closure of the growth plates, some patients have persistent symptoms. Excision of the ossicle and prominence of the tibial tuberosity decompresses the patellar tendon and allows most patients to resume sports activities. Nonsurgical modalities are ineffective. Better results have been reported after excision than after drilling of the tubercle. Excision of the ossicle is not indicated prior to skeletal maturity because symptoms will resolve in most patients when the secondary ossification center unites.
REFERENCES: Flowers MJ, Bhadreshwar DR: Tibial tuberosity excision for symptomatic Osgood-Schlatter disease. J Pediatr Orthop 1995;15:292-297.
Greene WB: Osteochondrosis and tibia vara, in Canale ST, Beaty JH (eds): Operative Pediatric Orthopaedics, ed 2. Philadelphia, Pa, Mosby, 1995, pp 804-854.

Question 2

A 10-lb, 2-oz infant who was born via a difficult breech delivery 12 hours ago is now being evaluated for hip pain. Although the infant is resting comfortably, examination reveals that the patient is not moving the right lower extremity and manipulation of the right hip causes the infant to cry. The Galeazzi sign is positive. An AP radiograph of the pelvis shows proximal and superior migration of the right proximal femoral metaphysis. What is the most likely diagnosis?

Explanation

DISCUSSION: Transphyseal fractures of the proximal femur at birth are more likely to occur in large newborns after a difficult delivery. At rest, the patients are comfortable and show a pseudoparalysis; however, passive motion of the lower extremity results in discomfort. Teratologic hip dislocations will have a positive Galeazzi sign, but are not painful. Development of a septic hip would be unlikely within 12 hours postpartum. Congenital coxa vara is typically painless. Postpartum ligamentous laxity might account for a positive Ortolani sign, but is painless.
REFERENCES: Weinstein JN, Kuo KN, Millar EA: Congenital coxa vara: A retrospective review. J Pediatr Orthop 1984;4:70-77.
Beaty JH: Orthopaedic Knowledge Update 6. Rosemont, Ill, American Academy of Orthopaedic Surgeons, 1999, pp 409-425.

Question 3

A 10-year-old girl has been referred for evaluation of a prominence at the lower cervical spine. The patient is asymptomatic, and the examination reveals no evidence of neurologic abnormality. A radiograph and CT scans are shown in Figures 12a through 12c. What is the most likely diagnosis?

Explanation

DISCUSSION: Tuberculosis is uncommon in the cervical spine but has a relatively greater incidence in young children. In a review of 40 patients with lower cervical spine involvement (C2 to C7), 24 were younger than age 10 years at presentation. In children, the disease is characterized by more extensive involvement with the formation of large abscesses. In older patients with lower cervical tuberculosis, the disease is more localized but is more likely to cause paraplegia. Four-drug antituberculosis therapy should be used. For patients with pain or neurologic dysfunction, anterior excision of diseased bone and grafting are indicated. Whether vertebral body excision and grafting should be done in an asymptomatic 10-year-old child is debatable. The CT scan shows a large “cold” abscess that is partially calcified.
REFERENCES: Hsu LC, Leong JC: Tuberculosis of the lower cervical spine (C2 to C7): A report on 40 cases. J Bone Joint Surg Br 1984;66:1-5.
Loder RT: The cervical spine, in Morrissy RT, Weinstein SL (eds): Lovell & Winter’s Pediatric Orthopaedics, ed 4. Philadelphia, Pa, Lippincott-Raven, 1996, pp 739-789.

Question 4

Which of the following types of iliac osteotomy provides the greatest potential for increased coverage?

Explanation

DISCUSSION: The degree of acetabular dysplasia and the age of the child are important considerations when choosing what type of osteotomy to perform. The ability to obtain concentric reduction is a prerequisite of all osteotomies that redirect the acetabulum. Procedures that cut all three pelvic bones allow more displacement and, therefore, correction of acetabular dysplasia. The closer the osteotomy is to the acetabulum, the greater the coverage of the femoral head. Compared with the other acetabular osteotomies, the Ganz periacetabular osteotomy provides the greatest potential for correcting acetabular deficiency because there are no bone or ligamentous restraints to limit correction, but it has the disadvantage of being a technically demanding procedure. The amount of coverage provided by the Salter osteotomy is limited.
REFERENCES: Millis MB, Poss R, Murphy SB: Osteotomies of the hip in the prevention and treatment of osteoarthritis, in Eilert RE (ed): Instructional Course Lectures XLI. Rosemont, Ill, American Academy of Orthopaedic Surgeons, 1992, pp 145-154.
Weinstein SL: Developmental hip dysplasia and dislocation, in Morrissy RT, Weinstein SL (eds): Lovell & Winter’s Pediatric Orthopaedics, ed 4. Philadelphia, Pa, Lippincott-Raven, 1996, pp 903-950.

Question 5

The mother of a 26-month-old boy reports that he has been unwilling to bear weight on his left lower extremity since he awoke this morning. She denies any history of trauma. He has a temperature of 99.4°F (37.4°C), and examination reveals that abduction of the left hip is limited to 30°. Laboratory studies show a WBC of 11,000/mm 3 and an erythrocyte sedimentation rate of 22 mm/h. A radiograph of the pelvis is shown in Figure 13. Management should consist of

Explanation

DISCUSSION: The most likely diagnosis is transient synovitis. Initial management should consist of bed rest and serial observation to rule out atypical septic arthritis of the hip. In an unreliable family situation, hospitalization for bed rest and observation may be indicated. Other disorders such as proximal femoral osteomyelitis, leukemia, juvenile rheumatoid arthritis, pelvic osteomyelitis, diskitis, and arthralgia secondary to other inflammatory disorders should be considered. However, these disorders are unlikely because of the paucity of abnormal clinical signs exhibited by the patient. On the other hand, transient synovitis of the hip in children is a diagnosis of exclusion; other possibilities should be explored if the patient’s symptoms do not follow a typical course and resolve in 4 to 21 days.
REFERENCE: Frymoyer JW (ed): Orthopaedic Knowledge Update 4. Rosemont, Ill, American Academy of Orthopaedic Surgeons, 1993, pp 505-513.

Question 6

A 10-year-old girl with a monoarticular pattern of juvenile rheumatoid arthritis (JRA) has had a 3-cm limb-length discrepancy since age 8 years when inflammation in the right knee came under good medical control. Because her right leg is longer, the patient states that she would like her legs to be close to equal in length in the future. A growth-remaining chart is shown in Figure 14. Management should consist of

Explanation

DISCUSSION: In a subgroup of patients with monoarticular JRA and a limb-length discrepancy that developed before the age of 9 years, Simon and associates showed that a subsequent growth deceleration on the affected side may correct a large part of the difference in length. This possibility would make surgery unnecessary and should prompt further observation.
REFERENCES: Simon S, Whiffen J, Shapiro F: Leg-length discrepancies in monoarticular and pauciarticular juvenile rheumatoid arthritis. J Bone Joint Surg Am 1981;63:209-215.
Ansell BM, Bywaters EGL: Growth in Still’s disease. Ann Rheum Dis 1956;15:295-319.

Question 7

A 14-year-old girl with polyarticular juvenile rheumatoid arthritis (JRA) has severe neck pain and reports the onset of urinary incontinence. A lateral radiograph and lateral tomogram of the cervical spine are shown in Figures 15a and 15b. An MRI scan of the upper cervical spine is shown in Figure 15c. Management should consist of

Explanation

DISCUSSION: The plain radiograph and tomogram show an abnormality of the upper cervical spine, with erosion of the dens. The MRI scan shows evidence of cord impingement. The cervical spine is frequently involved in polyarticular JRA. Stiffness and autofusion are commonly seen, but C1-2 instability can also occur secondary to synovitis and bony erosion. Basilar invagination is rare in JRA. There is no consensus regarding fusion in the asymptomatic patient. In patients with symptoms and neurologic signs, C1-2 posterior fusion is indicated.
REFERENCES: Fried JA, Athreya B, Gregg JR, Das M, Doughty R: The cervical spine in juvenile rheumatoid arthritis. Clin Orthop 1983;179:102-106.
Hensinger RN, DeVito PD, Ragsdale CG: Changes in the cervical spine in juvenile rheumatoid arthritis. J Bone Joint Surg Am 1986;68:189-198.

Question 8

Figures 16a and 16b show the radiographs of an otherwise healthy 3 1/2-year-old boy who has an isolated deformity of the left leg. Definitive primary treatment of this condition should consist of

Explanation

DISCUSSION: Treatment of congenital pseudarthrosis of the tibia is problematic. To achieve union, a resection of the pseudarthrosis, stabilization, and bone grafting must be performed. Simple cast immobilization does not yield union. There are various options for the resection, immobilization, and grafting. On the first surgical attempt, retrograde intramedullary nailing offers the best chance for success by transfixing the ankle and subtalar joints with abundant autogenous bone grafting. Distraction osteogenesis and vascularized free fibular graft are reserved as salvage procedures.
REFERENCES: Gilbert A, Brockman R: Congenital pseudarthrosis of the tibia: Long-term follow-up of 29 cases treated by microvascular bone transfer. Clin Orthop 1995;314:37-44.
Boero S, Catagni M, Donzelli O, Facchini R, Frediani PV: Congenital pseudarthrosis of the tibia associated with neurofibromatosis - 1: Treatment with Ilizarov’s device. J Pediatr Orthop 1997;17:675-684.
Anderson DJ, Schoenecker PL, Sheridan JJ, Rich MM: Use of an intramedullary rod for the treatment of congenital pseudarthrosis of the tibia. J Bone Joint Surg Am 1992;74:161-168.

Question 9

Figure 17 shows the radiograph of a 2-year-old girl who sustained a fracture of the femur in a fall while walking with her parents. History reveals that this is her third long bone fracture, having sustained a humerus fracture 1 year ago and a fracture of the opposite femur 9 months ago. There is no family history of any similar problem. Examination reveals distinctly blue sclerae, normal appearing teeth, and no skin lesions. What is the most likely cause of this patient’s disorder?

Explanation

DISCUSSION: Osteogenesis imperfecta (OI) is a genetically determined disorder of type I collagen synthesis that is characterized by bone fragility. This patient has had three fractures of the long bones by age 2 years, with the last one occurring after relatively minor trauma. The patient’s history and clinical features are consistent with a diagnosis of Sillence type IA OI. Type I OI is the mildest and most common form. Inheritance is autosomal-dominant; however, as in this patient, new mutations are frequent. Type I is subclassified into the A type (absence of dentinogenesis imperfecta) and B type (presence of dentinogenesis imperfecta). The sclerae are blue, and the first fractures usually occur in the preschool years after walking has begun. Cells from individuals with type I OI largely demonstrate a quantitative defect of type I collagen; they synthesize and secrete about half the normal amount of type I procollagen. Qualitative mutations that lead to an abnormal type I procollagen molecule result in more severe types of the disorder. There are no indications that this child has been abused. Radiographs of the femur show no evidence of rickets, pyknodysostosis, or osteopetrosis. Morquio syndrome, characterized by excess excretion of keratin sulfate in the urine, is not associated with bone fragility.
REFERENCES: Kocher MS, Shapiro F: Osteogenesis imperfecta. J Am Acad Orthop Surg 1998;6:225-236.
Sillence DO, Senn A, Danks DM: Osteogenesis imperfecta: An expanding panorama of variants. Clin Orthop 1981;159:11-25.
Cole WG: Etiology and pathogenesis of heritable connective tissue diseases. J Pediatr Orthop 1993;13:392-403.

Question 10

An 8-year-old boy with severe hemophilia A (factor VIII) and no inhibitor is averaging eight transfusions per month for bleeding into the right ankle. Examination shows synovial hypertrophy; range of motion consists of 0° of dorsiflexion and 20° of plantar flexion. The patient’s knees, elbows, and left ankle have no restriction of motion. Standing radiographs of the right ankle are shown in Figure 18. Management should consist of

Explanation

DISCUSSION: The patient has bilateral hypertrophic synovitis that is causing repeated hemarthroses and progressive arthropathy. Ankle synovectomy in patients with hemophilia is effective in significantly reducing the rate of joint bleeding and in slowing the progression of the arthropathy; therefore, bilateral synovectomies is the treatment of choice. Range of motion can be effectively maintained after ankle synovectomy. Bracing and prophylactic transfusions would be ineffective at this time. Ankle arthrodesis should be reserved for patients with severe pain. Compared with patients who have juvenile rheumatoid arthritis, patients with hemophilia generally do not have involvement of the subtalar joint and rarely require a pantalar arthrodesis.
REFERENCES: Greene WB: Synovectomy of the ankle for hemophilic arthropathy. J Bone Joint Surg Am 1994;76:812-819.
Greene WB: Chronic inflammatory arthridities and diseases related to the hematopoietic system, in Drennan JC (ed): The Child’s Foot and Ankle, New York, NY, Raven Press, 1992, pp 461-482.

Question 11

Figures 19a through 19c show radiographs of the cervical spine of an asymptomatic patient with Down syndrome who wants to participate in a Special Olympics running event. The neurologic examination is normal. Management should consist of

Explanation

DISCUSSION: An atlanto-dens interval (ADI) of up to 4 mm in children is considered normal. Children with Down syndrome have increased ligamentous laxity, with atlantoaxial instability occurring in as many as 15% to 20% of patients. These patients are at risk for catastrophic injury following minor trauma and should be routinely screened for instability, generally beginning when the patient starts to walk. Patients with an ADI of greater than 5 mm should avoid contact sports and high-risk activities such as gymnastics, diving, the high jump, and the butterfly stroke. The American Academy of Pediatrics Committee of Sports Medicine and Fitness guidelines recommend that lateral views of the cervical spine in neutral, flexion, and extension should be obtained in all children with Down syndrome who wish to participate in sports. Patients with normal radiographs and examinations do not need repeat radiographs, although some authors suggest that instability increases with age, and therefore recommend repeat radiographs every 5 years. Cervical spine fusion in patients with Down syndrome has a high rate of complications and should be performed only on patients with symptoms and evidence of myelopathy.
REFERENCES: American Academy of Pediatrics Committee of Sports Medicine and Fitness: Atlantoaxial instability in Down syndrome. Pediatrics 1995;96:151-154.
Copley LA, Dormans JP: Cervical spine disorders in infants and children. J Am Acad Orthop Surg 1998;6:204-214.
Tredwell SJ, Newman DE, Lockitch G: Instability of the upper cervical spine in Down syndrome. J Pediatr Orthop 1990;10:602-606.

Question 12

Compared with amputation, limb salvage for osteosarcoma of the distal end of the femur will result in

Explanation

DISCUSSION: Major advances in diagnostic imaging, neoadjuvant chemotherapy, and surgical techniques have allowed limb salvage to be performed as an alternative to amputation in children with osteosarcoma. The outcome of treatment of nonmetastatic, high-grade osteosarcoma of the distal femur was studied in 227 patients from 26 institutions. The authors found no difference in the long-term survival or quality of life between patients treated with limb salvage and those treated with amputation. Patients treated with limb salvage had a higher rate of reoperation, but a better functional outcome.
REFERENCES: Rougraff BT, Simon MA, Kneisl JS, Greenberg DB, Mankin HJ: Limb salvage compared with amputation for osteosarcoma of the distal end of the femur: A long-term oncological, functional, and quality-of-life study. J Bone Joint Surg Am 1994;76:649-656.
Simon MA: Limb salvage for osteosarcoma. J Bone Joint Surg Am 1988;70:307-310.

Question 13

Examination of a 7-year-old boy reveals 20° of valgus following a lawn mower injury to the lateral femoral epiphysis. Treatment consists of total distal femoral epiphyseodesis and varus osteotomy. Following surgery, he has a limb-length discrepancy of 3 cm and 5° of genu valgum. Assuming that he undergoes no further treatment, the patient’s predicted limb-length discrepancy at maturity would be how many centimeters?

Explanation

DISCUSSION: The distal femoral epiphysis grows approximately 1 cm per year and in boys, growth ceases at approximately age 16 years. Therefore, the patient’s limb-length discrepancy at maturity would be 12 cm (9 cm plus the 3-cm discrepancy he has from the previous surgery).
REFERENCES: Little DG, Nigo L, Aiona MD: Deficiencies of current methods for the timing of epiphyseodesis. J Pediatr Orthop 1996;16:173-179.
Westh RN, Menelaus MB: A simple calculation for the timing of epiphyseal arrest: A further report. J Bone Joint Surg Br 1981;63:117-119.

Question 14

When the iliac apophysis starts ossifying in the normal adolescent, growth of the sitting height or trunk height is characterized by

Explanation

DISCUSSION: Studies by Anderson and associates have resulted in a growth-remaining chart for sitting height that shows an increase of 3 to 5 cm in girls and an increase of 5 to 8 cm in boys. Future growth of the spine may impact brace longevity and fit.
REFERENCES: Anderson M, Hwang SC, Green WT: Growth of the normal trunk in boys and girls during the second decade of life: Related to age, maturity, and ossification of the iliac epiphyses. J Bone Joint Surg Am 1965;47:1554-1564.
Zaoussis AL, James JIP: The iliac apophysis and the evolution of curves in scoliosis. J Bone Joint Surg Br 1958;40:442-453.

Question 15

A 10-year-old girl was thrown over the handlebars of her bicycle and landed directly on her left shoulder. She was treated with a figure-of-8 strap and analgesics. Follow-up examination 2 weeks later reveals that the lateral end of the clavicle is superiorly dislocated relative to the acromion. A radiograph of the shoulder shows calcification lateral to the coracoid process at the level of the acromion, and the clavicle is superiorly displaced. Management should consist of

Explanation

DISCUSSION: In adults, a direct blow on the acromion usually results in an acromioclavicular dislocation. In children, however, the usual injury from this mechanism is a physeal fracture of the lateral clavicle. The clavicular shaft fragment, analogous to the metaphyseal portion of a physeal fracture, herniates through the periosteum, leaving the distal periosteal sleeve in contact with the lateral (distal) physeal fragment. The treatment of choice is immobilization until the patient is pain-free.
REFERENCES: Falstie-Jensen S, Mikkelsen P: Pseudodislocation of the acromioclavicular joint. J Bone Joint Surg Br 1982;64:368-369.
Havranek P: Injuries of the distal clavicular physis in children. J Pediatr Orthop 1989;9:213-215.

Question 16

Figures 20a and 20b show the radiographs of an obese 15-year-old boy who has severe left groin pain and is unable to bear weight following a minor injury. Treatment should consist of

Explanation

DISCUSSION: The radiographs and history are consistent with an acute unstable slipped capital femoral epiphysis. Aronson and Loder documented an increased rate of osteonecrosis associated with manipulative reduction. They recommended bed rest with skin traction to allow the synovitis to resolve, followed by in situ pinning. They noted, however, that many of these slips reduced with anesthesia and positioning on a fracture table. Biomechanic studies have shown a slight increased resistance to shear stress when two screws are used, but it is unknown if this is significant in the clinical setting. Open epiphyseodesis does not provide postoperative stability; therefore, adjunctive fixation or immobilization is required. Numerous studies have noted the inadvisability of using multiple screws. Casting has a high rate of complications, including chondrolysis and progression of the slip.
REFERENCES: Aronson DD, Loder RT: Treatment of the unstable (acute) slipped capital femoral epiphysis. Clin Orthop 1996;322:99-110.
Karol LA, Doane RM, Cornicelli SF, Zak PA, Haut RC, Manoli A II: Single versus double screw fixation for treatment of slipped capital femoral epiphysis: A biomechanical analysis. J Pediatr Orthop 1992;12:741-745.
Stanitski CL: Acute slipped capital femoral epiphysis: Treatment alternatives. J Am Acad Orthop Surg 1994;2:96-106.

Question 17

What is the recommended treatment of a skeletally immature 12-year-old boy who has an anterior cruciate ligament-deficient knee?

Explanation

DISCUSSION: Traditional surgeries for anterior cruciate ligament-deficient knees carry the potential risk of premature physeal closure in young athletes. Therefore, most surgeons are reluctant to recommend intra-articular reconstruction using bone tunnels with bone-patellar tendon-bone autografts or hamstring tendons. The current recommendation for young athletes is activity modification, rehabilitation, and functional bracing until the patient is near skeletal maturity. At that time, for the very symptomatic patient, the treatment of choice is intra-articular repair of the anterior cruciate ligament. If a skeletally immature patient continues to have instability despite rehabilitation and bracing, a modification of the femoral tunnel to the over-the-top position will not place the lateral femoral physis at risk for premature closure and deformity. A centrally placed tibial tunnel will minimize the risk of angular deformity and minimize limb-length discrepancy if physeal arrest occurs.
REFERENCES: Barry P: Anterior cruciate ligament injuries, in Andrews JR, Timmerman LA (eds): Diagnostic and Operative Arthroscopy. Philadelphia, Pa, WB Saunders, 1997, p 358.
McCarroll JR, Shelbourne KD, Porter DA, Rettig AC, Murray S: Patellar tendon graft reconstruction for midsubstance anterior cruciate ligament rupture in junior high school athletes: An algorithm for management. Am J Sports Med 1994;22:478-484.
Nottage WM, Matsuura PA: Management of complete traumatic anterior cruciate ligament tears in the skeletally immature patient: Current concepts and review of the literature. Arthroscopy 1994;10:569-573.
Stanitski CL: Anterior cruciate ligament injury in the skeletally immature patient: Diagnosis and treatment. J Am Acad Orthop Surg 1995;3:146-158.

Question 18

Figures 21a and 21b show the radiographs of a 12-year-old patient with an L4-level myelomeningocele who has scoliosis that has been slowly progressing for the past several years. There has been no loss of motor function. An MRI scan shows no syringomyelia or increased hydrocephalus. Management should consist of

Explanation

DISCUSSION: Scoliosis is a common occurrence in children with myelomeningocele, with the incidence increasing as the neurologic level moves cephalad. The rate of pseudarthrosis for isolated anterior or posterior fusions has been reported as high as 75%. The combination of anterior and posterior fusions with some type of instrumentation has been shown to decrease the rate of pseudarthrosis to 20%. Brace treatment in smaller curves can be used as a temporizing measure to delay surgery, but as with idiopathic scoliosis, the brace is ineffective for larger curves. Observation is not indicated with a curve of this magnitude.
REFERENCES: Ward WT, Wenger DR, Roach JW: Surgical correction of myelomeningocele scoliosis: A critical appraisal of various spinal instrumentation systems. J Pediatr Orthop 1989;9:262-268.
Muller EB, Nordwall A: Brace treatment of scoliosis in children with myelomeningocele. Spine 1994;19:151-155.

Question 19

A 3-year-old child is referred for evaluation of bowed legs. History reveals no dietary deficiencies; however, family history is significant for several members with bowed legs. Examination reveals genu varum, and the child is in the 5th percentile for height and weight. Laboratory studies show normal renal function, a normal calcium level, a decreased phosphate level, and an elevated alkaline phosphatase level. A plain radiograph of the lower extremities is shown in Figure 22. What is the most likely diagnosis?

Explanation

DISCUSSION: The differential diagnosis of genu varum includes physiologic genu varum, Blount's disease, skeletal dysplasia, and metabolic bone disease. Children with Blount's disease are generally in the 95th percentile for height and weight, and usually multiple family members are not affected. The radiographs show widening of the physis and metaphyseal flaring. In Blount's disease, the characteristic radiographic changes involve only the tibia, and at this age, most commonly show beaking of the medial metaphysis. Skeletal dysplasias, such as chondrometaphyseal dysplasia, are associated with short stature, and the radiographic changes are similar to those seen here. However, laboratory studies in these children will be within normal limits. Children with chronic renal disease will often be of short stature, and the radiographic findings are again similar to those shown here. However, BUN and creatinine levels are elevated and phosphate levels are elevated rather than decreased in children with renal disease. The absence of dietary deficiencies and positive family history rules out vitamin D-deficient rickets. There are four types of vitamin D-resistant rickets: failure of production of 1,25-dihydroxy vitamin D, phosphate diabetes (hypophosphatemic rickets), end organ insensitivity to vitamin D, and renal tubular acidosis. All types of vitamin D-resistant rickets are resistant to treatment with physiologic doses of vitamin D. The patient’s clinical picture, family history, laboratory studies, and radiographs are most consistent with hypophosphatemic rickets. This entity is inherited as a sex-linked dominant trait.
REFERENCES: Evans GA, Arulanantham K, Gage JR: Primary hypophosphatemic rickets: Effect of oral phosphate and vitamin D on growth and surgical treatment. J Bone Joint Surg Am 1980;62:1130-1138.
Loeffler RD Jr, Sherman FC: The effect of treatment on growth and deformity in hypophosphatemic vitamin D-resistant rickets. Clin Orthop 1982;162:4-10.
Loder RT, Johnston CE II: Infantile tibia vara. J Pediatr Orthop 1987;7:639-646.
Bassett GS, Scott CI: The osteochondrodysplasias, in Morrissy RT (ed): Pediatric Orthopaedics, ed 3. Philadelphia, Pa, JB Lippincott, 1990, vol 1, pp 91-142.

Question 20

A 14-year-old boy sustained a femoral neck fracture in a fall from a tree and underwent open reduction and internal fixation 6 months ago. Follow-up examination now reveals an antalgic Trendelenburg gait and painful range of motion. A radiograph is shown in Figure 23, and a CT scan shows a nonunion. Treatment should consist of

Explanation

DISCUSSION: The coxa vara deformity and fracture nonunion should be treated simultaneously; therefore, the treatment of choice is curettage of the nonunion, intertrochanteric valgus osteotomy, and revision internal fixation. In addition, valgus osteotomy will convert the shear forces across the nonunion to compression, aiding in healing of the nonunion. None of the other procedures addresses both issues, and hip fusion is inappropriate under these conditions.
REFERENCES: Lam SF: Fractures of the neck of the femur in children. J Bone Joint Surg Am 1971;53:1165-1179.
Canale ST, Beaty JH: Pelvic and hip fractures, in Rockwood CA Jr, Wilkins KE, Beaty JH (eds): Fractures in Children. Philadelphia, Pa, Lippincott-Raven, 1996, pp 1109-1193.

Question 21

A 22-month-old child has scrapes and bruises on his head and a severe deformity of the forearm after being thrown from a car as an unrestrained passenger in a motor vehicle accident. Examination reveals a Glasgow Coma Scale score of 12. Prior to treatment of the forearm, management should include

Explanation

DISCUSSION: As CT scanning has become available, the use of radiographs of the skull has decreased in importance for evaluation of head trauma. The indications for CT scanning for suspected head trauma include any degree of obtundation, focal neurologic deficit, history of a high-velocity injury, amnesia for the injury, progressive headache, persistent vomiting, children younger than age 2 years, serious facial injury, posttraumatic seizure, skull penetration, or a Glasgow Coma Scale score of 13 or less. Evidence of improved outcome with use of steroids in head trauma is lacking. Steroids are useful for increased intracranial pressure caused by brain tumors or abscesses. High-dose IV methylprednisolone is indicated for spinal cord trauma and improves the ultimate degree of recovery of function. When herniation is suspected in a patient with asymmetric neurologic findings or the patient’s condition is deteriorating rapidly, a mannitol infusion may be used.
REFERENCES: Hall DE: Head injuries, in Hoekelman RA (ed): Primary Pediatric Care. St Louis, Mo, Mosby, 1997, pp 1709-1712.
Nelson WE, Behrman RE, Kliegman RM (eds): Nelson Essentials of Pediatrics. Philadelphia, Pa, WB Saunders, 1998, p 712.
Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, Ill, American Academy of Orthopaedic Surgeons, 1999, pp 123-130.

Question 22

Examination of a 5-year-old boy with amyoplasia shows a flexion contracture of 70° of the right knee. The active arc of motion is from 70° to 90°, and the opposite knee has a flexion contracture of 10°. Both hips are dislocated with flexion contractures of 10°, passive hip motion is from 10° to 90° of flexion, and the feet are plantigrade and easily braceable. Despite a daily stretching program, the parents and physical therapists note that it is increasingly difficult for him to walk because of the flexion contracture of the right knee. Management of the knee flexion contracture should now include

Explanation

DISCUSSION: Most children with amyoplasia are ambulatory and when a decrease in function occurs because of a severe contracture, it must be addressed. A radical posterior soft-tissue release, including the posterior knee capsule and often the collateral ligaments and the posterior cruciate ligament, is needed to obtain extension. After the age of 1 year, aggressive physical therapy will do little to correct a contracture. Botulinum toxin A is indicated for spasticity and is contraindicated with severe contractures. Supracondylar femoral extension osteotomy works well, but will remodel at an average rate of 1° per month, which is not considered ideal in a young patient. Gradual correction with a circular ring external fixator is an option, but a soft-tissue release will also most likely be needed for a contracture of this severity.
REFERENCES: Sarwark JF, MacEwen GD, Scott CI Jr: Amyoplasia (a common form of arthrogryposis). J Bone Joint Surg Am 1990;72:465-469.
DelBello DA, Watts HG: Distal femoral extension osteotomy for knee flexion contracture in patients with arthrogryposis. J Pediatr Orthop 1996;16:122-126.
Sells JM, Jaffe KM, Hall JG: Amyoplasia, the most common type of arthrogryposis: The potential for good outcome. Pediatrics 1996;97:225-231.

Question 23

A 13-year-old girl who is 2 years postmenarche has been referred for management of scoliosis. She denies any history of back pain. Radiographs show a right thoracic curve of 35°. She has a Risser sign of 4 and a bone age of 15.5 years. Management should consist of

Explanation

DISCUSSION: Because the patient is skeletally mature with a curve of less than 40°, there is no benefit to bracing and surgery is not indicated. Management should consist of observation and follow-up radiographs in 6 months.
REFERENCES: Lonstein JE, Carlson JM: The prediction of curve progression in untreated idiopathic scoliosis during growth. J Bone Joint Surg Am 1984;66:1061-1071.
Frymoyer JW (ed): Orthopaedic Knowledge Update 4. Rosemont, Ill, American Academy of Orthopaedic Surgeons, 1993, pp 447-459.

Question 24

In children with isolated zone II lacerations of the flexor tendon, poor digital motion is best correlated with

Explanation

DISCUSSION: In a recent study on restoration of motion following zone I and zone II flexor tendon repairs in children, age was found to have no effect on the results of zone II tendon repairs. Early passive motion offered no better results than immobilization for 3 weeks. Immobilization for more than 4 weeks correlated with poorer results.
REFERENCE: O’Connell SJ, Moore MM, Strickland JW, Frazier GT, Dell PC: Results of zone I and zone II flexor tendon repairs in children. J Hand Surg Am 1994;19:48-52.

Question 25

In a longitudinal study of children with spastic diplegia, analysis of long-term function will most likely reveal

Explanation

DISCUSSION: In a longitudinal study of 18 patients with spastic diplegia over a period of 32 months, three-dimensional gait analysis revealed a deterioration of gait stability with increases in double support time and decreases in single support time. Kinematic data also identified a loss of excursion about the knee, ankle, and pelvis. Interestingly, the static examination of the children showed a decrease in the popliteal angle over time. The authors concluded that ambulatory ability tends to worsen over time in children with spastic diplegia.
REFERENCE: Johnson DC, Damiano DL, Abel MF: The evolution of gait in childhood and adolescent cerebral palsy. J Pediatr Orthop 1997;17:392-396.

Question 26

Examination of a 7-year-old girl with myelomeningocele reveals calcaneal deformities of both feet. She ambulates on both extremities wearing ankle-foot orthoses and has no upper extremity aids. She has grade 5/5 motor strength to the tibialis anterior muscles and absent motor strength to the triceps surae. There is no varus or valgus deformity of the hindfoot, and the skin over the heels is intact; however, mild callosities are present. Management should consist of

Explanation

DISCUSSION: A calcaneal deformity of the foot may occur in children who have low lumbar myelomeningocele. Strong dorsiflexors overcome a weak or absent gastrocnemius-soleus complex, leading to downward growth of the calcaneal apophysis. The deformity is usually progressive and does not respond to nonsurgical management. Most authorities recommend transfer of the tibialis anterior muscle through the interosseous membrane to the posterior aspect of the calcaneus. This procedure has been reported to be effective in limiting progression of the deformity. An extra-articular subtalar arthodesis, a treatment option for valgus deformity of the hindfoot, is not indicated. Similarly, Achilles tendon tenodesis to the fibula, an option for managing valgus of the ankle, is not indicated. Calcaneal osteotomy may be used in older children with severe calcaneal deformity.
REFERENCES: Stott NS, Zionts LE, Gronley JK, Perry J: Tibialis anterior transfer for calcaneal deformity: A postoperative gait analysis. J Pediatr Orthop 1996;16:792-798.
Georgiadis GM, Aronson DD: Posterior transfer of the anterior tibial tendon in children who have a myelomeningocele. J Bone Joint Surg Am 1990;72:392-398.

Question 27

Figure 24 shows the radiograph of a 4-year-old girl with spina bifida. Examination reveals an L3 motor level, excellent sitting and standing balance, and satisfactory range of motion at the hips. Management should consist of

Explanation

DISCUSSION: Children with spina bifida and bilateral symmetrical dislocation of the hips usually do not require treatment. A level pelvis and good range of motion of the hips are more important for ambulation than reduction of bilateral hip dislocations. Because the patient has good sitting and standing balance and good range of motion, maintenance of that range of motion and symmetry is more important than reduction. Surgery is not recommended.
REFERENCE: Heeg M, Broughton NS, Menelaus MB: Bilateral dislocation of the hip in spina bifida: A long-term follow-up study. J Pediatr Orthop 1998;18:434-436.

Question 28

Posterior spinal fusion for scoliosis should be performed on a patient with Duchenne muscular dystrophy when

Explanation

DISCUSSION: Progressive scoliosis develops in most patients with Duchenne muscular dystrophy. The onset of spinal deformity typically follows the cessation of walking, and curves can be expected to progress about 10° per year. Posterior spinal fusion with instrumentation should be performed as soon as a curve of 25° or greater is documented and before deterioration of pulmonary function (a FVC of less than 30%) precludes surgery. Patients with kyphotic posture tend to progress more rapidly than those with lordotic posture. Brace treatment is contraindicated because it is not definitive and it may mask curve progression while pulmonary function is concomitantly worsening.
REFERENCES: Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, Ill, American Academy of Orthopaedic Surgeons, 1999, pp 635-651.
Mubarak SJ, Morin WD, Leach J: Spinal fusion in Duchenne muscular dystrophy: Fixation and fusion to the sacropelvis? J Pediatr Orthop 1993;13:752-757.

Question 29

Figures 25a and 25b show the radiograph and MRI scan of a 7 1/2-year-old boy who has been limping for 1 year. His pain has worsened over the past 2 weeks, and his parents note swelling over the dorsum of the foot for the past 4 days. Examination reveals no fever, and laboratory studies show a WBC of 6,700/mm 3 , an erythrocyte sedimentation rate of 26 mm/h, and a normal C-reactive protein level. What is the most likely diagnosis?

Explanation

DISCUSSION: The diagnosis of tuberculous osteomyelitis in children is often delayed. In one series of 23 children, the average interval between the onset of symptoms and definite diagnosis was 4.3 months. In these patients, the presenting signs and symptoms were found to be mild, with the most common signs being localized swelling (69.6%) and a painful disability of the involved limbs (65.2%). A mild elevation of the erythrocyte sedimentation rate may be present, but the C-reactive protein level is usually normal. In patients who have osteoarticular tuberculosis, an MRI scan generally shows large intra-articular effusions, periarticular osteoporosis, and gross thickening of the synovial membrane. Differential diagnosis between tuberculosis and pyogenic arthritis is difficult, and an accurate diagnosis usually requires biopsy of synovial tissue. Aspiration of synovial fluid often results in insufficient information to make a diagnosis. Treatment generally consists of surgical debridement and combined antituberculous chemotherapy with isoniazid, ethambutol, and rifampin.
REFERENCES: Wang MN, Chen WM, Lee KS, Chin LS, Lo WH: Tuberculous osteomyelitis in young children. J Pediatr Orthop 1999;19:151-155.
Watts HG, Lifeso RM: Tuberculosis of the bones and joints. J Bone Joint Surg Am 1996;78:288-298.

Question 30

A 10-year-old boy who plays baseball reports acute pain after throwing a softball from the outfield to second base. A radiograph is shown in Figure 26. Management should consist of

Explanation

DISCUSSION: The patient has a fracture through a unicameral bone cyst, as evidenced by the “falling leaf” sign on the radiograph. Following healing of the fracture, treatment should consist of corticosteroid injection or bone marrow injection. Some cysts heal with the fracture and do not require injections. Biopsy is unnecessary because the radiograph shows that the cyst is benign. Curettage and bone grafting are seldom necessary because these cysts regularly heal with injections. Corticosteroids are useful when injected into the cyst, but are not used systemically. Pulsed electromagnetic fields have not been used therapeutically in this condition.
REFERENCE: Yandow SM, Lundeen GA, Scott SM, Coffin C: Autogenic bone marrow injections as a treatment for simple bone cyst. J Pediatr Orthop 1998;18:616-620.

Question 31

The mother of an otherwise healthy 1-month-old infant reports that he is not moving his left leg after falling from his high chair 2 days ago. He has a temperature of 99.5°F (37.5°C). Examination reveals that the left thigh is moderately tender to palpation. Because the infant is apprehensive, range of motion is difficult to quantify, but appears to be normal at the hips and ankles. Range of motion of the left knee is approximately 25° to 90°. A radiograph of the leg is shown in Figure 27. Management should consist of

Explanation

DISCUSSION: The patient has a bucket-handle fracture of the distal femur with bilateral corner fractures of the distal femur and a transverse fracture of the proximal tibia. These fractures are virtually pathognomonic of child abuse. The infant should be admitted to the hospital, and child protection services should be notified for investigation of possible abuse. A skeletal survey should be obtained, along with laboratory studies that include a CBC, a platelet count, a prothrombin time, a partial thromboplastin time, and a bleeding time.
REFERENCES: Akbarnia BA: The role of the orthopaedic surgeon in child abuse, in Morrissy RT, Weinstein SL (eds): Lovell & Winter’s Pediatric Orthopaedics, ed 4. Philadelphia, Pa, Lippincott-Raven, 1996, pp 1315-1334.
Black GB: Child abuse fractures, in Letts RM (ed): Management of Pediatric Fractures. New York, NY, Churchill Livingstone, 1994, pp 931-944.

Question 32

A 12-year-old girl with juvenile rheumatoid arthritis (JRA) has had chronic pain and synovitis about the knee that is now well-controlled medically. Examination reveals 20° of valgus at the knee. Knee range of motion shows 10° to 90° of flexion. Treatment should consist of

Explanation

DISCUSSION: Children with JRA frequently have valgus in association with hypervascularity because of chronic inflammation. This is normally caused by overgrowth of the medial femoral epiphysis. Staple hemiepiphyseodesis, if done early, can reverse the deformity. Osteotomy is usually unnecessary at this age, and there is a risk of stiffness of the knee following the procedure. Synovectomy may be helpful but will not prevent or correct a deformity.
REFERENCE: Rydholm U, Brattstrom H, Bylander B, Lidgren L: Stapling of the knee in juvenile chronic arthritis. J Pediatr Orthop 1987;7:63-68.

Question 33

Figure 28 shows the radiograph of a 6-year-old girl who has a right thoracic scoliosis that measures 60°. Examination shows multiple cafe-au-lait spots, and family history reveals that the child’s mother has the same disorder. The gene responsible for this disorder codes for

Explanation

DISCUSSION: The patient has the dystrophic type of scoliosis seen in patients with neurofibromatosis type I (NF-1). The NF-1 gene is located on chromosome 17 and codes for neurofibromin, believed to be a tumor-suppresser gene. Abnormalities in the dystrophin gene are seen in Duchenne muscular dystrophy and Becker muscular dystrophy. A mutation in the frataxin gene is responsible for Friedreich ataxia. The most common type of hereditary motor and sensory neuropathy (Charcot-Marie-Tooth), HMSN type IA is caused by a complete duplication of the peripheral myelin protein gene. A defect in the cellular sulfate transport protein results in undersulfation of proteoglycans seen in diastrophic dysplasia.
REFERENCE: Beaty JH: Orthopaedic Knowledge Update 6. Rosemont, Ill, American Academy of Orthopaedic Surgeons, 1999, pp 225-234.

Question 34

Figures 29a and 29b show the radiographs of a 13-year-old competitive gymnast who has had elbow pain for the past 2 weeks. The pain is worse with tumbling activities. Examination reveals a mild effusion and slight limitation of extension and forearm rotation with no locking. Initial management should consist of

Explanation

DISCUSSION: The radiographs show a lesion in the capitellum that is consistent with osteochondritis dissecans. There is no evidence of a loose body at this time. Initial management should consist of cessation of gymnastic activities. Nonsteroidal anti-inflammatory drugs and ice may help to alleviate acute symptoms; most symptoms usually resolve in 6 to 12 weeks. The patient may then begin range-of-motion and strengthening exercises, with a slow return to activities once full range of motion and good strength have been achieved. However, the prognosis for a return to high-level competitive gymnastics is guarded. Surgery is indicated for intra-articular loose bodies, a locked elbow, or failure of nonsurgical management. Surgery may be done either open or arthroscopically. Loose bodies should be removed, and cartilage flaps should be debrided. The results of bone grafting and internal fixation generally have been poor. Drilling the base of the defect may stimulate replacement with fibrocartilage, but the benefits of this procedure are not well documented.
REFERENCES: Maffulli N, Chan D, Aldridge MJ: Derangement of the articular surfaces of the elbow in young gymnasts. J Pediatr Orthop 1992;12:344-350.
Bauer M, Jonsson K, Josefsson PO, Linden B: Osteochondritis dissecans of the elbow: A long-term follow-up study. Clin Orthop 1992;284:156-160.
Tivnon MC, Anzel SH, Waugh TR: Surgical management of osteochondritis dissecans of the capitellum. Am J Sports Med 1976;4:121-128.

Question 35

A 12-year-old boy who has had a 1-month history of right thigh pain and a limp reports worsening of the pain after a fall, and he can no longer walk or bear weight on the involved extremity. Radiographs of the pelvis reveal a slipped capital femoral epiphysis with moderate to severe displacement. While positioning the patient on the fracture table for screw fixation, partial reduction of the slip is achieved. No further reduction maneuvers are attempted, and the epiphysis is stabilized with a single cannulated screw. What complication is most likely to develop following this procedure?

Explanation

DISCUSSION: Traditional classification of slipped capital femoral epiphyses is based on the following temporal criteria: acute (symptoms that persist for less than 3 weeks); chronic (symptoms that persist for more than 3 weeks); or acute on chronic (acute exacerbation of long-standing symptoms). A newer classification differentiates between a stable slip where weight bearing is possible, and an unstable slip if it is not. Reduction of an unstable slip often occurs unintentionally with induction of anesthesia and positioning of the patient for surgery. The rate of satisfactory results is lower primarily because of a much higher incidence of osteonecrosis following internal fixation of an unstable slip.
REFERENCES: Loder RT, Richards BS, Shapiro PS, Reznick LR, Aronson DD: Acute slipped capital femoral epiphysis: The importance of physeal stability. J Bone Joint Surg Am 1993;75:1134-1140.
Richards BS (ed): Orthopaedic Knowledge Update: Pediatrics. Rosemont, Ill, American Academy of Orthopaedic Surgeons, 1996, pp 151-159.

Question 36

Figure 30 shows the AP radiograph of a 9-month-old girl who has been referred for evaluation of unequal leg lengths. Examination reveals symmetrical abduction of the hips. When the hips are flexed 90°, the right knee height is greater than the left knee. The girth of the right thigh and calf is larger than the contralateral side. There are no cutaneous lesions, and examination of the spine is normal. The infant is moving all extremities equally and spontaneously. Management should consist of

Explanation

DISCUSSION: Hemihypertrophy or hemihypotrophy is usually idiopathic, and either the leg or the entire side of the body may be involved. In the infant or young child, it is often difficult to determine which side is abnormal if the condition is mild. Because of the association of Wilms’ tumor with hemihypertrophy, these patients should undergo a yearly renal ultrasound until at least age 5 years. Other conditions that may exhibit hemihypertrophy include Klippel-Trenaunay-Weber syndrome, Proteus syndrome, and neurofibromatosis. In this patient, the mild hemihypertrophy is idiopathic. Because of the normal spinal examination and absence of neurologic findings, an MRI scan is unnecessary. The absence of clinical and radiographic evidence of hip dysplasia makes both an ultrasound of the hips and application of a Pavlik harness unnecessary.
REFERENCES: Richards BS (ed): Orthopaedic Knowledge Update: Pediatrics. Rosemont Ill, American Academy of Orthopaedic Surgeons, 1996, pp 185-193.
Sponseller PD: Localized disorders of bone and soft tissue, in Morrissy RT, Weinstein SL (eds): Lovell and Winter’s Pediatric Orthopaedics, ed 4. Philadelphia, Pa, Lippincott-Raven, 1996, pp 305-344.
Beals RK: Hemihypertrophy and hemihypotrophy. Clin Orthop 1982;166:199-203.

Question 37

What is the mechanism of action of an intramuscular injection of botulinum type A toxin in reducing spasticitiy?

Explanation

DISCUSSION: The use of intramuscular botulinum type A toxin has been shown to be a useful adjuvant in the management of dynamic deformity in patients with cerebral palsy. Botulinum type A toxin is a neurotoxin produced by Clostridium botulinum that works by interfering with presynaptic acetylcholine release at cholinergic nerve terminals. At the cellular level, the mechanism involves endocytosis of the intact botulinum toxin molecule by cells in the end plate, followed by disulfide cleavage and translocation of the light chain into the cytosol where it disrupts the normal binding of the synaptosomal vesicles to the axon terminal membrane. Neither the nerve terminal nor the neuromuscular junction is damaged. The muscle paralysis is reversible and dose-dependent. Baclofen is a neuropharmacologic agent that functions as a GABA agonist. Dorsal rhizotomy is a neurosurgical procedure that reduces spasticity by dividing afferent (excitatory) fibers in the posterior rootlet of the spinal nerves.
REFERENCES: Koman LA, Mooney JF III, Smith B, Goodman A, Mulvaney T: Management of cerebral palsy with botulinum-A toxin: Preliminary investigation. J Pediatr Orthop 1993;13:489-495.
Brin MF: Botulinum toxin: Chemistry, pharmacology, toxicity, and immunology. Muscle Nerve Suppl 1997;6:S146-168.

Question 38

A 5-year-old boy has had right hip pain and a limp for the past 3 months. Examination of the right hip reveals irritability and restricted abduction and internal rotation. AP and lateral radiographs of the hips are shown in Figures 31a and 31b. Initial management should consist of

Explanation

DISCUSSION: A favorable prognosis can be expected in up to 70% of children with Legg-Calve-Perthes disease who are younger than age 6 years. Containment treatment has not been shown to alter the outcome in this age group. The goals of treatment in this patient are to reduce pain (synovitis), restore motion, and improve function. Symptomatic treatment modalities include bed rest, traction, crutches, activity modification, and nonsteroidal anti-inflammatory drugs.
REFERENCES: Herring JA: The treatment of Legg-Calve-Perthes disease: A critical review of the literature. J Bone Joint Surg Am 1994;76:448-458.
Richards BS (ed): Orthopaedic Knowledge Update: Pediatrics. Rosemont, Ill, American Academy of Orthopaedic Surgeons, 1996, pp 161-166.

Question 39

Hamstring lengthening and posterior transfer of the rectus femoris will be most successful in a patient with cerebral palsy who has which of the following gait abnormalities?

Explanation

DISCUSSION: Children with cerebral palsy typically ambulate with a crouched gait characterized by excessive flexion of the hips and knees during stance. Many patients exhibit co-contracture of the quadriceps and hamstrings, causing a stiff-knee gait. Normally, the rectus femoris fires at the initiation of swing and in terminal swing through initial contact. Prolonged activity of the rectus femoris throughout the swing phase interferes with normal knee flexion. This contributes to a stiff knee during swing phase and prevents clearance of the foot. Lengthening of the hamstrings alone will not improve foot clearance. Hamstring lengthening is contraindicated when there is hyperextension during stance. Transfer of the rectus femoris to one of the knee flexors has been shown to improve knee flexion during swing by an average of 15°. This allows improved foot clearance.
REFERENCES: Gage JR, Perry J, Hicks RR, Koop S, Werntz JR: Rectus femoris transfer to improve knee function of children with cerebral palsy. Dev Med Child Neurol 1987;29:159-166.
Sutherland DH, Santi M, Abel MF: Treatment of stiff-knee gait in cerebral palsy: A comparison by gait analysis of distal rectus femoris transfer versus proximal rectus release. J Pediatr Orthop 1990;10:433-441.

Question 40

Figures 32a and 32b show the radiographs of a 13-year-old boy who sustained a fracture while playing football 1 week ago. Management at the time of injury included application of a cast and the use of crutches. A follow-up office visit reveals a normal neurologic examination, and the patient reports no discomfort with the cast and crutches. Management should now include

Explanation

DISCUSSION: Stable fractures and minimally displaced fractures in children can and should be treated by closed methods. Because loss of reduction is common, alignment of tibia fractures must be monitored closely for the first 3 weeks after cast application. This is most easily handled in a cooperative patient by cast wedging. Some children require application of a second cast under general anesthesia 2 to 3 weeks after injury, particularly if the subsidence of swelling has caused the cast to loosen. Surgical indications include the presence of soft-tissue injuries, unstable fracture patterns, fractures associated with compartment syndrome, and the child with multiple injuries. Surgical options in children include percutaneous pins, external fixation, plates and screws, and intramedullary nails.
REFERENCES: Heinrich SD: Fractures of the shaft of the tibia and fibula, in Rockwood CA, Wilkins KE, Beaty JH (eds): Fractures in Children, ed 4. Philadelphia, Pa, Lippincott-Raven, 1996, pp 1340-1346.
Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, Ill, American Academy of Orthopaedic Surgeons, 1999, pp 583-595.

Question 41

A 14-year-old patient with an L3 myelomeningocele underwent anterior and posterior spinal fusion for a curve of 50°. Follow-up examination 1 week after the procedure now reveals persistent drainage from the posterior wound. Results of laboratory cultures show Streptococcus viridans, Staphylococcus aureus, and Enterococcus. In addition to IV antibiotics, surgical irrigation, and debridement, management should include

Explanation

DISCUSSION: The rate of wound infections has dramatically decreased with the routine use of prophylactic antibiotics. Factors known to increase the risk of infection include instrumentation, prolonged surgical time, excessive blood loss, poor perioperative nutritional status, a history of surgery, and a history of infection. The use of allograft does not result in an increased rate of infection. Adequate treatment requires early diagnosis and intervention. Temperature elevation and persistent wound drainage are highly suspicious for infection. An erythrocyte sedimentation rate and a WBC are not useful in diagnosis unless serial examinations show rising levels. Patients should be taken to the operating room where the entire wound can be reopened, irrigated, and debrided. Bone graft can be washed and replaced. Hardware should not be removed. The wound should be closed over suction drains. IV antibiotics should be given for a period of at least 10 days, followed by 6 weeks orally. Leaving the wound open to granulate with dressing changes results in prolonged hospitalization, inadequate treatment of the infection, and a poor cosmetic result.
REFERENCES: Lonstein JE: Complications of treatment, in Bradford DS, Lonstein JE, Moe JH, et al (eds): Moe’s Textbook of Scoliosis and Other Spinal Deformities, ed 2. Philadelphia, Pa, WB Saunders, 1987, p 476.
Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, Ill, American Academy of Orthopaedic Surgeons, 1999, pp 713-721.

Question 42

What is the primary mechanism of injury for the fracture shown in Figures 33a and 33b?

Explanation

DISCUSSION: The radiographs show a triplane fracture of the ankle. In adolescence, closure of the distal tibial physis starts peripherally at the anteromedial aspect of the medial malleolus and extends posteriorly and laterally. The anterolateral quadrant of the physis is the last to close, making this region the most susceptible to separation. When the foot is twisted into external rotation, the anterolateral portion of the epiphysis is avulsed by the pull of the anterior tibiofibular ligament. When this fragment alone is avulsed, the result is a juvenile Tillaux fracture. When the fracture extends to involve the remainder of the physis and posterior metaphysis, as in this patient, the result is a triplane fracture.
REFERENCES: Richards BS (ed): Orthopaedic Knowledge Update: Pediatrics. Rosemont, Ill, American Academy of Orthopaedic Surgeons, 1996, pp 267-272.
Dias LS, Giegerich CR: Fractures of the distal tibial epiphysis in adolescence. J Bone Joint Surg Am 1983;65:438-444.
Kling TF Jr: Operative treatment of ankle fractures in children. Orthop Clin North Am 1990;21:381-392.

Question 43

Figure 34 shows the standing AP radiograph of a 2-year-old girl who has a left bowleg deformity. Her mother states that she first noticed the problem when the child began walking at age 10 months, and the deformity has worsened over the past 6 months. Examination reveals a definite lateral thrust of the knee during the stance phase of gait. Management should consist of

Explanation

DISCUSSION: Infantile tibia vara is a developmental condition characterized by a varus angulation of the proximal end of the tibia that is caused by a growth disturbance of the proximal medial physis. In a study of 42 affected extremities in 24 children younger than age 3 years, it was found that daytime ambulatory brace treatment favorably altered the natural history of tibia vara. Another study of 27 patients with stage II Langenskiöld disease found a success rate of 70% (improved alignment without the need for osteotomy) using brace treatment. These authors also noted that children with unilateral disease were more likely to obtain correction of the deformity compared with those with bilateral disease. In this patient, observation is not warranted because untreated tibia vara has a significant risk for progressive worsening. Osteotomy is best reserved for those patients who, despite bracing, do not show satisfactory clinical and radiographic improvement by age 4 years. Elevation of the medial tibial plateau is a treatment option for older patients who have more advanced disease. An MRI scan would not provide any useful clinical information at this time.
REFERENCES: Zionts LE, Shean CJ: Brace treatment of early infantile tibia vara. J Pediatr Orthop 1998;18:102-109.
Richards BS, Katz DE, Sims JB: Effectiveness of brace treatment in early infantile Blount’s disease. J Pediatr Orthop 1998;18:374-380.
Raney EM, Topoleski TA, Yaghoubian R, Guidera KJ, Marshall JG: Orthotic treatment of infantile tibia vara. J Pediatr Orthop 1998;18:670-674.

Question 44

Figures 35a and 35b show the radiographs of a 7-year-old patient who has progressive deformity of the right thigh accompanied by a dull persistent pain radiating to the knee. Examination reveals an obvious bulge in the right thigh, with flexion of the hip beyond 50° only if the hip is allowed to externally rotate. Management should consist of

Explanation

DISCUSSION: The patient has radiographic signs of osteogenesis imperfecta, including osteopenia, mild acetabular protrusio, cortical thinning, and bowing associated with anterior stress fracturing. The treatment of choice is correction of the bow with osteotomies, followed by intramedullary fixation to prevent further deformity. Biphosphonates, such as pamidronate, may be useful in increasing bone density and preventing fractures. Large multicenter studies on biphosphonate efficacy are currently in progress.
REFERENCES: Zionts LE, Ebramzadeh E, Stott NS: Complications in the use of the Bailey-Dubow extensible nail. Clin Orthop 1998;348:186-195.
Luhmann SJ, Sheridan JJ, Capelli AM, Schoenecker PL: Management of lower-extremity deformities in osteogenesis imperfecta with extensible intramedullary rod technique: A 20-year experience. J Pediatr Orthop 1998;18:88-94.
Glorieux FH, Bishop NJ, Plotkin H, Chabot G, Lanoue G, Travers R: Cyclic administration of pamidronate in children with severe osteogenesis imperfecta. N Engl J Med 1988;339:947-952.

Question 45

Figures 36a and 36b show the MRI scans of a 15-year-old girl who has had pain and recurrent hemarthrosis in the knee for the past year. Plain radiographs are normal. What is the most likely diagnosis?

Explanation

DISCUSSION: In pediatric patients who have pain and recurrent hemarthrosis in the knee, hemangioma is often seen as an internal derangement of the knee, and long delays in diagnosis are common. An MRI scan is noninvasive and will best aid in diagnosis. In this patient, the MRI scan shows a hemangioma with no evidence of meniscal injury or discoid meniscus. Hemophilia is unlikely because the patient is female. The presence of hemarthrosis makes JRA an unlikely diagnosis.
REFERENCE: Price NJ, Cundy PJ: Synovial hemangioma of the knee. J Pediatr Orthop 1997;17:74-77.

Question 46

A 2-year-old child has marked hypotonia and depressed reflexes. History reveals that the child was normal at birth and developed normally for the first year. The child also began to ambulate, but lost this ability during the next 6 months. Laboratory studies show a creatine phosphokinase level that is within the normal range. DNA testing confirms a deletion in the survival motor neuron (SMN) gene. What is the most likely diagnosis?

Explanation

DISCUSSION: The patient has spinal muscular atrophy, type 2. This type is intermediate in severity between the Werdnig-Hoffmann type (type 1) and the Kugelberg-Welander type

(type 3). It normally manifests itself between the ages of 3 and 15 months. Survival until adolescence is common. All three types of spinal muscular atrophy have been linked to the SMN gene at the 5q12.2-13.3 locus. DNA testing is available and is preferred to muscle biopsy because it is less invasive and more definitive.
REFERENCES: Biros I, Forrest S: Spinal muscular atrophy: Untangling the knot? J Med Genet 1999;36:1-8.
Zerres K, Wirth B, Rudnik-Schoneborn S: Spinal muscular atrophy: Clinical and genetic correlations. Neuromuscul Disord 1997;7:202-207.

Question 47

A 13-year-old boy sustains a valgus stress injury to the knee while playing football, and he is unable to bear weight after the injury. Examination reveals tenderness medially superior to the joint line. The knee is held in flexion, and he has a large effusion and localized medial swelling. Plain radiographs show no obvious fracture. What is the next diagnostic step?

Explanation

DISCUSSION: In the skeletally mature individual, this mechanism of injury will often result in a sprain of the medial collateral ligament. In skeletally immature patients, the same mechanism can cause a fracture of the distal femoral physis. If the fracture is nondisplaced, the plain radiographs may show only soft-tissue swelling or effusion. While the MRI scan may show edema in the soft tissues on the medial side of the knee and even an abnormality of the physis, stress radiographs provide a quicker and less expensive means of making the diagnosis. Arthroscopy and arthrography would not be helpful in making the diagnosis. Arthroscopy may result in further displacement of the injury.
REFERENCES: Smith L: Concealed injury to the knee. J Bone Joint Surg Am 1962;44:1659-1660.
Beaty JH, Kumar A: Fractures about the knee in children. J Bone Joint Surg Am 1994;76:1870-1880.

Question 48

Figure 37 shows the clinical photograph of a 1-day-old infant who weighed 10.25 lb at birth. Examination reveals an absent right Moro reflex and limited active motion of the right shoulder, elbow, and wrist, but flexion of the fingers. Passive range of motion of the shoulder and elbow is normal. What is the most likely diagnosis?

Explanation

DISCUSSION: The patient’s right upper extremity is held in the “head waiter’s” posture with the shoulder internally rotated, the elbow extended, and the wrist in flexion. The Erb type of obstetrical brachial plexus palsy involves the C5 and C6 nerve root, and occasionally, as in this child, the C7 nerve root. Obstetrical palsy is a traction injury, and is associated with a high birth weight, shoulder dystocia, cephalopelvic disproportion, or the use of forceps. Erb palsy is four times more common than injury to the entire plexus or injury to the C8 and T1 nerve roots. It results from the shoulder being depressed while the head and neck are laterally rotated, extended, and tilted in the opposite direction. Most patients recover wrist extension and elbow flexion. Patients with residual weakness of shoulder external rotation and abduction will benefit from release of the pectoralis major, latissimus dorsi, and teres major, with transfer of the latissimus dorsi and the teres major to the posterosuperior aspect of the rotator cuff. Recent studies using arthrograms and CT scans have shown a higher incidence of posterior glenoid deficiency and posterior subluxation than that observed with plain radiographs. The posterior subluxation or dislocation can be effectively reduced by tendon release and transfer procedures.
REFERENCES: Hoffer MM, Phipps GJ: Closed reduction and tendon transfer for treatment of dislocation of the glenohumeral joint secondary to brachial plexus birth palsy. J Bone Joint Surg Am 1998;80:997-1001.
Pearl ML, Edgerton BW: Glenoid deformity secondary to brachial plexus birth palsy. J Bone Joint Surg Am 1998;80:659-667.
Waters PM, Smith GR, Jaramillo D: Glenohumeral deformity secondary to brachial plexus birth palsy. J Bone Joint Surg Am 1998;80:668-677.

Question 49

Figure 38 shows the radiograph of a 5-year-old child who sustained a type III supracondylar fracture. Examination reveals the absence of a radial pulse, but an otherwise well-perfused hand. Following closed reduction and percutaneous pinning, the radial pulse remains absent; however, the hand is pink and well perfused. Management should now include

Explanation

DISCUSSION: In a study of over 400 patients with displaced supracondylar fractures, 3.2% of the fractures were associated with the absence of the radial pulse with an otherwise well-perfused hand. Based on this study, a period of close observation with frequent neurovascular checks should be completed before attempting invasive correction of the problem. Because of the satisfactory results with expectant management, angiography, exploration, removal of fixation and exploration, and thrombectomy are contraindicated.
REFERENCE: Sabharwal S, Tredwell SJ, Beauchamp RD, Mackenzie WG, Jakubec DM, Cairns R: Management of pulseless pink hand in pediatric supracondylar fractures of humerus. J Pediatr Orthop 1997;17:303-310.

Question 50

Figures 39a and 39b show the radiographs of an otherwise healthy 10-year-old boy who has had thigh pain and a limp for the past 9 months. Examination reveals that the left lower extremity is 1 cm shorter, with reduced flexion, abduction, and internal rotation on the left side. The patient is at the 50th percentile for height and the 90th percentile for weight. Serum studies will most likely show

Explanation

DISCUSSION: The patient has a slipped capital femoral epiphysis (SCFE) at a younger than average age (average age 13.5 years for boys and 12.0 years for girls); therefore, an etiology that is not idiopathic must be considered. Hypothyroidism can result in a SCFE, but these children typically fall into the category of less than the 10th percentile for height. SCFE may develop in children with a growth hormone deficiency who have undergone hormonal replacement. Osteodystrophy caused by chronic renal failure may result in a SCFE, but the bone quality is markedly osteopenic on radiographs and the children are chronically ill with both low height and weight percentiles. An elevated estrogen level results in physeal closure and is protective to physeal slippage. Therefore, this child will most likely have normal laboratory values.
REFERENCES: Loder RT, Hensinger RN: Slipped capital femoral epiphysis associated with renal failure osteodystrophy. J Pediatr Orthop 1997;17:205-211.
Loder RT, Wittenberg B, DeSilva G: Slipped capital femoral epiphysis associated with endocrine disorders. J Pediatr Orthop 1995;15:349-356.

Question 51

A 13-year-old obese boy presents to the emergency department with severe left hip pain and inability to bear weight for the past 24 hours. Radiographs confirm a slipped capital femoral epiphysis (SCFE). He cannot ambulate even with crutches. Which of the following management strategies minimizes the risk of avascular necrosis in this patient?

Explanation

This is an unstable SCFE, defined by the inability to bear weight, which carries a high risk of avascular necrosis (AVN). Urgent incidental reduction, fixation, and capsulotomy/decompression is advocated to relieve intracapsular tamponade and reduce AVN risk.

Question 52

A 60-year-old man presents with progressive clumsiness in his hands and a wide-based gait. Imaging reveals multi-level ossification of the posterior longitudinal ligament (OPLL) from C3 to C6. The K-line on the sagittal T1 MRI is negative. What is the most appropriate surgical management?

Explanation

A negative K-line indicates that the anterior compressive lesion (OPLL) is so large that the spinal cord will not shift posteriorly enough to be adequately decompressed by a posterior approach alone. Therefore, an anterior decompression and fusion (or combined approach) is required.

Question 53

During an anterior intrapelvic (modified Stoppa) approach for acetabular fracture fixation, significant arterial bleeding is encountered near the superior pubic ramus. This bleeding is most likely originating from an anastomosis between which two vessels?

Explanation

The corona mortis is a vascular anastomosis between the external iliac (or inferior epigastric) and the obturator vessels. It is located over the superior pubic ramus and is highly vulnerable during the anterior intrapelvic approach.

Question 54

A 13-year-old boy presents with severe left hip pain and inability to bear weight after a minor fall 2 days ago. Radiographs demonstrate a displaced slipped capital femoral epiphysis (SCFE). Which of the following is the most significant prognostic factor for the development of avascular necrosis (AVN)?

Explanation

An unstable slip, defined by the inability to bear weight even with crutches, is the most significant risk factor for developing AVN. Rates of AVN in unstable SCFE can be as high as 47%, compared to nearly 0% in stable SCFE.

Question 55

A 24-year-old football player sustains a direct blow to the anteromedial aspect of his knee while it is hyperextended. Examination reveals increased external rotation of the tibia at 30 degrees of knee flexion, but symmetrical external rotation at 90 degrees compared to the contralateral leg. What is the most likely injured structure?

Explanation

An isolated posterolateral corner (PLC) injury presents with increased external rotation at 30 degrees of flexion but not at 90 degrees on the Dial test. If external rotation is increased at both 30 and 90 degrees, a combined PLC and PCL injury should be suspected.

Question 56

A 65-year-old man presents with progressive difficulty buttoning his shirts and a worsening gait. Examination shows a positive Hoffman's sign, hyperreflexia in the lower extremities, and ankle clonus. An MRI of the cervical spine is most likely to show compression at which level to explain both upper and lower extremity findings?

Explanation

The patient's symptoms indicate cervical spondylotic myelopathy. Compression at a higher cervical level like C3-C4 affects the long tracts to the lower extremities (hyperreflexia, gait issues) as well as the upper extremity fine motor skills.

Question 57

A 28-year-old man is involved in a high-speed motor vehicle collision and sustains a vertically oriented (Pauwels type III) femoral neck fracture. Which fixation construct provides the most biomechanically stable construct for this specific fracture pattern?

Explanation

Pauwels type III fractures are highly unstable due to significant vertical shear forces across the fracture line. A dynamic hip screw (fixed-angle device) supplemented with a derotational screw provides superior biomechanical stability against shear stress compared to multiple cancellous screws.

Question 58

A 55-year-old active woman undergoes a total hip arthroplasty with a ceramic-on-ceramic bearing surface. Three years later, she complains of a newly developed, audible squeaking from the hip with deep flexion. Radiographs are normal. What is the most common cause of this phenomenon?

Explanation

Squeaking in ceramic-on-ceramic total hip arthroplasty is most commonly associated with component malpositioning leading to microseparation and edge loading. It typically does not indicate catastrophic failure if radiographs remain normal.

Question 59

A 22-year-old skier hears a pop in her knee after a twisting injury. Radiographs show a small avulsion fracture of the lateral tibial plateau (Segond fracture). This radiographic finding is virtually pathognomonic for an injury to which of the following structures?

Explanation

A Segond fracture is a cortical avulsion of the anterolateral capsule from the lateral tibial plateau. It is considered highly pathognomonic for an anterior cruciate ligament (ACL) tear.

Question 60

A 42-year-old roofer falls 15 feet, landing on his feet. He complains of severe back pain. CT shows an L1 burst fracture with 60% canal compromise. He is neurologically intact. Which of the following is the strongest indication for operative stabilization?

Explanation

In a neurologically intact patient with a thoracolumbar burst fracture, disruption of the posterior ligamentous complex (PLC) indicates gross spinal instability and is a primary indication for surgery. Canal compromise alone, without neurological deficit or PLC injury, can often be managed conservatively.

Question 61

A 35-year-old pedestrian is struck by a car and sustains a medial tibial plateau fracture with depression and a fractured medial intercondylar eminence (Schatzker Type IV). What is the classic mechanism of injury for this fracture pattern?

Explanation

Schatzker IV fractures involve the medial tibial plateau and are typically caused by a high-energy varus force combined with axial loading. They have a higher association with peroneal nerve traction injuries and popliteal artery damage than lateral plateau fractures.

Question 62

A 30-year-old man presents with a posterior hip dislocation and a femoral head fracture located superior to the fovea capitis. According to the Pipkin classification, what type of fracture is this, and what is the preferred surgical approach for fixation?

Explanation

A femoral head fracture superior to the fovea capitis (involving the primary weight-bearing portion) is a Pipkin Type II fracture. The anterior (Smith-Petersen) approach is generally preferred for optimal visualization and perpendicular screw fixation of anterior/superior femoral head fragments.

Question 63

A 45-year-old male laborer complains of medial-sided left knee pain. Radiographs show isolated medial compartment osteoarthritis and varus alignment. He has full range of motion and a stable knee. Which of the following is the primary biomechanical goal of a high tibial osteotomy (HTO) in this patient?

Explanation

The primary goal of a valgus-producing high tibial osteotomy is to unload the arthritic medial compartment by shifting the mechanical axis slightly lateral to the midline of the knee (typically 62% of the tibial width). This relieves pain and slows the progression of medial compartment arthritis.

Question 64

A 50-year-old woman presents with acute low back pain radiating down the lateral aspect of her right leg to the dorsum of her foot. She has weakness in the extensor hallucis longus (EHL) but normal ankle and patellar reflexes. Which nerve root is most likely compressed, and at which classic disc herniation level?

Explanation

Weakness in the extensor hallucis longus and pain radiating to the dorsum of the foot are classic signs of L5 radiculopathy. In the lumbar spine, a posterolateral disc herniation at the L4-L5 level most commonly compresses the traversing L5 nerve root.

Question 65

A 25-year-old man is brought in hypotensive after a motorcycle crash. Pelvic radiographs reveal a 4 cm diastasis of the pubic symphysis and disruption of the anterior sacroiliac joints, but intact posterior sacroiliac ligaments. What is the most appropriate initial management for his hemodynamic instability?

Explanation

This is an anteroposterior compression (APC) Type II injury resulting in an open-book pelvis and increased pelvic volume. A pelvic binder should be applied immediately and centered over the greater trochanters to effectively close the pelvic ring and aid in hemorrhage control.

Question 66

A 4-week-old female infant is diagnosed with a completely dislocated left hip that is reducible on examination (Ortolani positive). A Pavlik harness is applied. At the 3-week follow-up ultrasound, the hip remains persistently dislocated. What is the most appropriate next step in management?

Explanation

Failure of a Pavlik harness to achieve reduction of a dislocated hip within 3 to 4 weeks is an absolute indication to discontinue the harness to prevent Pavlik harness disease (posterior acetabular wear). The next appropriate step is typically a closed reduction and spica casting under anesthesia.

Question 67

A 17-year-old female dancer requires medial patellofemoral ligament (MPFL) reconstruction for recurrent lateral patellar instability. Which of the following radiographic landmarks correctly describes the anatomic femoral attachment of the MPFL (Schottle's point)?

Explanation

Schottle's point marks the anatomic femoral origin of the MPFL on lateral fluoroscopy. It is located dynamically between the medial epicondyle and the adductor tubercle, specifically proximal and posterior to the medial epicondyle.

Question 68

A 72-year-old man sustains a Type II odontoid fracture after a ground-level fall. The fracture is displaced 6 mm posteriorly. What is the most significant risk factor for non-union if this fracture is treated non-operatively with a rigid cervical collar?

Explanation

In Type II odontoid fractures, age greater than 65 years is one of the most significant risk factors for non-union, with non-union rates exceeding 50% in this demographic when treated non-operatively. Displacement greater than 5 mm is also a major risk factor.

Question 69

A 25-year-old male is brought to the ED after a motor vehicle collision. He is awake, alert, and neurologically intact. Radiographs reveal a bilateral C5-C6 facet dislocation. What is the most appropriate next step in management?

Explanation

In an awake, alert, and cooperative patient with a cervical facet dislocation, urgent closed reduction with skeletal traction is indicated before an MRI. MRI is required prior to open reduction or in a patient with altered mental status to evaluate for disc herniation.

Question 70

A 70-year-old active female undergoes total hip arthroplasty (THA) for a displaced femoral neck fracture. Compared to patients undergoing THA for primary osteoarthritis, this patient is at the highest increased risk for which of the following postoperative complications?

Explanation

Patients undergoing THA for acute femoral neck fractures have a significantly higher risk of postoperative dislocation compared to those undergoing elective THA for osteoarthritis. This is primarily due to acute soft tissue laxity and the absence of preexisting protective capsular contractures.

Question 71

A 6-year-old boy presents with a painless clicking and "snapping" sensation in his lateral knee during terminal extension. MRI confirms a Wrisberg variant of a lateral discoid meniscus. What is the defining anatomic feature of this meniscal variant?

Explanation

The Wrisberg variant of a discoid meniscus lacks the normal posterior meniscotibial (coronary) ligament attachments, making it highly mobile. It attaches posteriorly only via the meniscofemoral ligament of Wrisberg, leading to the classic "snapping" knee upon extension.

Question 72

A hemodynamically unstable 35-year-old male sustains an anteroposterior compression type III (APC-III) pelvic ring injury. A circumferential pelvic binder is applied in the trauma bay. To optimally reduce the pelvic volume and stabilize the fracture, the binder should be centered over which anatomic landmark?

Explanation

A pelvic binder must be centered directly over the greater trochanters to effectively close the pelvic ring and reduce pelvic volume. Placement over the iliac crests or ASIS can paradoxically open the pelvis further and exacerbate hemorrhage.

Question 73

When planning corrective surgery for adult spinal deformity, sagittal balance is a critical parameter for postoperative clinical outcomes. The surgical goal should aim for a mismatch between Pelvic Incidence (PI) and Lumbar Lordosis (LL) of:

Explanation

In adult spinal deformity surgery, achieving a Pelvic Incidence to Lumbar Lordosis (PI-LL) mismatch of less than 10 degrees is highly correlated with improved health-related quality of life scores. Failure to restore this balance increases the risk of adjacent segment disease and hardware failure.

Question 74

During a primary posterior-stabilized total knee arthroplasty, the knee is found to be properly balanced in extension but excessively tight in flexion. Which of the following surgical steps is the most appropriate to resolve this kinematic mismatch?

Explanation

A knee that is tight in flexion but balanced in extension has a contracted flexion gap. Decreasing the anteroposterior size of the femoral component will enlarge the flexion gap without affecting the extension gap.

Question 75

A 45-year-old male sustains a high-energy Schatzker type IV tibial plateau fracture. Which of the following vascular structures is at highest risk of injury due to the specific mechanism and displacement pattern of this fracture?

Explanation

Schatzker IV fractures involve the medial tibial plateau and often result from high-energy varus forces with potential knee subluxation. This specific displacement pattern places the popliteal artery at high risk of tethering and intimal injury at the fibrous arch of the soleus.

Question 76

A 55-year-old male with a metal-on-metal total hip arthroplasty presents with groin pain and swelling 5 years postoperatively. Serum cobalt and chromium levels are significantly elevated. MRI reveals a large, cystic pseudotumor. What is the most appropriate definitive management?

Explanation

The patient is experiencing an adverse local tissue reaction (ALTR) secondary to metal wear debris. Definitive treatment requires extensive soft tissue debridement and revision of the bearing surfaces to a non-metal articulation, most commonly ceramic-on-polyethylene.

Question 77

A 60-year-old male presents with worsening sacral pain and bowel/bladder dysfunction. Imaging reveals a large, destructive, midline lytic lesion involving the S2-S4 segments. Biopsy demonstrates a lobulated architecture with physaliferous cells containing large intracytoplasmic vacuoles. What is the recommended treatment?

Explanation

The biopsy findings of physaliferous cells in a midline sacral mass are pathognomonic for chordoma. Chordomas are locally aggressive and largely resistant to standard chemotherapy and radiation, making wide en bloc surgical excision the definitive treatment of choice.

Question 78

A 28-year-old male sustains an isolated, closed midshaft femur fracture. He undergoes reamed intramedullary nailing 12 hours after injury. Postoperatively, he develops acute hypoxia, a petechial rash on the axillae, and altered mental status. What is the primary pathophysiologic mechanism for this condition?

Explanation

The classic triad of hypoxia, petechial rash, and neurologic abnormalities indicates Fat Embolism Syndrome (FES). It is caused by the systemic release of bone marrow fat globules and inflammatory mediators into the venous circulation following long bone fractures and reaming.

Orthopedic Surgery Board Review MCQs: Arthroplasty, Trauma & Spine Part 255

Orthopedic Board Review MCQs: Hip, Knee, Spine & Trauma | Part 13

Key Takeaway

Orthopedic Board Review MCQs: Hip, Knee, Spine & Trauma | Part 13

Chapter Index