Correct Answer: A

A Type I SLAP lesion is characterized by fraying and degeneration of the superior labrum, but the biceps anchor remains firmly attached to the glenoid. Treatment typically involves simple debridement. Type II involves detachment of the superior labrum and biceps anchor. Type III is a bucket-handle tear of the labrum with an intact biceps anchor. Type IV is a bucket-handle tear extending into the biceps tendon.

Correct Answer: B

Hinge abduction occurs when the extruded, enlarged anterolateral portion of the femoral head impinges on the lateral margin of the acetabulum during abduction. Persistent hinge abduction prevents the acetabulum from effectively remodeling the femoral head, leading to a permanently deformed, aspherical femoral head (coxa magna) and early osteoarthritis. It does not cause premature closure of the triradiate cartilage or avascular necrosis of the acetabulum.

Correct Answer: C

Lipohemarthrosis is characterized by the layering of fat and blood within a joint cavity. The most common cause is an intra-articular fracture, which allows marrow fat to escape into the joint space. On MRI, it typically shows a superior layer of fat, a central layer of serum, and an inferior layer of red blood cells. While an ACL tear causes a hemarthrosis, it does not typically cause a lipohemarthrosis unless accompanied by an osteochondral fracture.

Correct Answer: B

Forceful closed reduction of a slipped capital femoral epiphysis is contraindicated because it significantly increases the risk of osteonecrosis (avascular necrosis) of the femoral head by disrupting the already tenuous retinacular blood supply. The standard of care is in situ fixation. Spica casting is generally not used as primary treatment due to poor control and stiffness, but closed reduction is the most dangerous intervention listed.

Correct Answer: B

The clinical presentation, imaging (cortically based lytic lesion with surrounding sclerosis/edema), and histology (vascular stroma with osteoblasts and woven bone) are classic for an osteoid osteoma. Percutaneous radiofrequency ablation (RFA), typically under CT guidance, has become the preferred treatment method, offering high success rates with minimal morbidity compared to open surgical excision.

Correct Answer: A

The Bernese periacetabular osteotomy (PAO) is designed to reorient the acetabulum to improve femoral head coverage. A key biomechanical goal and advantage of the PAO is the ability to medialize the hip joint center, which decreases the joint reactive forces by reducing the lever arm of the body weight, thereby improving the mechanical environment of the dysplastic hip.

Correct Answer: C

The radiographs show a volar Barton's fracture (volar displaced intra-articular fracture of the distal radius). The primary deforming forces are axial loading and volar shear, which cause the carpus to subluxate volarly with the fracture fragment. A volar buttress plate is applied to physically block (buttress) this volar displacement, neutralizing the axial and shearing forces.

Correct Answer: B

The clinical, radiographic (ground-glass appearance, Shepherd's crook deformity), and histologic ('Chinese letter' woven bone lacking osteoblastic rimming in a fibrous stroma) findings are diagnostic of fibrous dysplasia. Fibrous dysplasia is caused by a somatic, post-zygotic activating mutation in the GNAS1 gene, which encodes the alpha subunit of the stimulatory G protein (Gs-alpha), leading to increased intracellular cAMP and abnormal osteoblast differentiation.

Correct Answer: C

Synovial herniation pits (Pitt's pits) are benign, often incidental, radiolucent lesions with sclerotic margins typically located in the anterosuperior femoral neck. They are thought to result from mechanical abrasion and herniation of synovium into the bone. They are highly associated with cam-type femoroacetabular impingement (FAI), where the abnormal femoral head-neck junction abuts the acetabular rim.

Correct Answer: B

The radiograph demonstrates a Lisfranc injury (tarsometatarsal fracture-dislocation). The Lisfranc ligament is a critical stabilizing structure of the midfoot. Its primary, strongest, and most important band (the interosseous Lisfranc ligament) attaches from the lateral aspect of the medial cuneiform to the medial aspect of the base of the second metatarsal. There is no direct ligamentous connection between the first and second metatarsal bases.

Correct Answer: Type I; arthroscopic debridement

The arthroscopic image demonstrates a Type I SLAP (Superior Labrum Anterior and Posterior) lesion, which is characterized by fraying and degeneration of the superior labrum with an intact biceps anchor. The appropriate treatment for a Type I SLAP lesion is simple arthroscopic debridement. Biceps tenodesis or tenotomy is not indicated because the biceps anchor is stable. Type II lesions involve detachment of the superior labrum and biceps anchor and are typically treated with repair. Type III lesions are bucket-handle tears of the labrum with an intact biceps anchor, and Type IV lesions are bucket-handle tears that extend into the biceps tendon.

Correct Answer: Hinge abduction

The arthrogram images demonstrate classic hinge abduction, a critical finding in severe Legg-Calvé-Perthes disease. Hinge abduction occurs when the enlarged, deformed lateral portion of the femoral head extrudes and impinges against the lateral margin of the acetabulum during abduction. Instead of gliding smoothly into the acetabulum, the femoral head hinges on the acetabular rim, causing the medial joint space to widen (distract), which is visualized as medial dye pooling on the arthrogram. Persistent hinge abduction prevents normal spherical remodeling of the femoral head and is an indication for surgical intervention to restore congruency.

Correct Answer: Intra-articular fracture

The MRI scan demonstrates a lipohemarthrosis, characterized by the layering of fat, serum, and red blood cells in the joint space. The superior layer contains fat (high signal intensity on T1), the middle layer contains serum, and the dependent layer contains red blood cells. The presence of a lipohemarthrosis is highly indicative of an intra-articular fracture, which allows marrow fat to escape into the joint cavity. While ligamentous and meniscal injuries can cause a hemarthrosis, they do not typically introduce marrow fat into the joint unless accompanied by an osteochondral defect or fracture.

Correct Answer: Transtendon arthroscopic repair

The images demonstrate a PASTA lesion (Partial Articular-Sided Tendon Avulsion). When a PASTA lesion involves greater than 50% of the tendon footprint thickness, surgical repair is generally indicated. An accepted and common technique is a transtendon arthroscopic repair, which allows the surgeon to secure the articular-sided tear down to the footprint without taking down the intact bursal-sided tissue. This preserves the intact lateral fibers of the rotator cuff while restoring the medial footprint anatomy.

Correct Answer: Percutaneous radiofrequency ablation

The clinical presentation (night pain relieved by NSAIDs), radiographic appearance (cortically based lytic lesion with surrounding sclerosis/edema), and histology (plump osteoblasts producing woven bone in a vascular stroma) are classic for an osteoid osteoma. Percutaneous radiofrequency ablation (RFA), typically performed under CT guidance, has become the preferred, minimally invasive treatment of choice for most osteoid osteomas, offering high success rates and low morbidity compared to open surgical resection or curettage.

Correct Answer: Bernese (Ganz) periacetabular osteotomy

The radiograph shows symptomatic developmental dysplasia of the hip (DDH) with significant anterolateral undercoverage. In a young, active patient with preserved joint space and symptomatic dysplasia, a redirectional pelvic osteotomy is indicated to improve femoral head coverage and biomechanics, thereby delaying or preventing the onset of osteoarthritis. The Bernese (Ganz) periacetabular osteotomy is the most widely accepted procedure for this indication in adults, as it allows for multiplanar correction while maintaining the integrity of the posterior column.

Correct Answer: It neutralizes axial loading forces on the fractured volar fragment.

The radiographs demonstrate a volar Barton's fracture, which is a volar displaced intra-articular fracture-dislocation of the distal radius. The volar carpal ligaments remain attached to the volar fragment, pulling the carpus volarly. A volar buttress plate is biomechanically ideal for this injury because it acts as an anti-glide plate, neutralizing the axial loading and shear forces that drive the fragment proximally and volarly. A dorsal plate would not provide this buttress effect and would make maintaining the reduction difficult.

Correct Answer: Open reduction and internal fixation with a locked plate

The patient has a displaced periprosthetic distal femur fracture above a well-fixed femoral component. Because the component is a posterior-stabilized closed-box design, retrograde intramedullary nailing is contraindicated (the box prevents nail passage). Since the component is well-fixed, revision arthroplasty is unnecessary and would sacrifice bone stock. Therefore, open reduction and internal fixation (ORIF) with a locked laterally based plate is the most appropriate treatment to provide stable fixation while preserving the prosthesis.

Correct Answer: Fibrous dysplasia

The clinical, radiographic, and histologic findings are classic for fibrous dysplasia. Radiographically, it presents as a lytic, expansile lesion with a 'ground-glass' matrix, often leading to bowing deformities in the proximal femur known as a 'Shepherd's crook' deformity. Histologically, it is characterized by a fibrous stroma containing irregular, woven bone trabeculae that lack osteoblastic rimming, often described as having a 'Chinese letter' or 'alphabet soup' appearance.

Correct Answer: Phleboliths associated with a hemangioma

The presence of small, rounded calcifications in a soft-tissue mass on radiographs is highly suggestive of phleboliths, which are calcified thrombi within the venous channels of a hemangioma. The MRI findings of a heterogeneous mass with high T1 signal (due to interspersed fat) further support the diagnosis of an intramuscular hemangioma. Myositis ossificans typically shows peripheral ossification, while chondroid matrix usually appears as stippled or rings-and-arcs calcifications.

Correct Answer: Arthroscopic debridement

The image and description correspond to a Type I SLAP lesion (fraying of the superior labrum with an intact biceps anchor). The appropriate treatment is simple debridement. Biceps tenodesis or release is not indicated because the biceps tendon and anchor are intact. There is no indication for labral repair or capsulorrhaphy.

Correct Answer: Arthroscopic labral repair

The image shows a Type II SLAP tear (detachment of the superior labrum and biceps anchor). In a young, competitive overhead athlete, arthroscopic labral repair is the treatment of choice to restore anatomy and function. Labral debridement leads to predictably poor results in this demographic, while biceps tenodesis or tenotomy is generally reserved for older patients or those who are not competitive overhead athletes.

Correct Answer: Hinge abduction

The arthrogram demonstrates hinge abduction, a severe complication of Legg-Calvé-Perthes disease where the deformed, extruded lateral portion of the femoral head hinges against the lateral acetabular margin during abduction, preventing concentric reduction. This persistent hinge abduction prevents femoral head remodeling by the acetabulum.

Correct Answer: Intra-articular fracture

The MRI shows lipohemarthrosis, characterized by layering of fat (superior, high signal on T1), serum (central, low signal), and red blood cells (inferior, low signal). This finding is highly indicative of an intra-articular fracture, which allows marrow fat to escape into the joint space.

Correct Answer: Excision of osteophytes and loose bodies with capsular release

The radiograph and history are classic for primary degenerative arthritis of the elbow, characterized by osteophytes on the coronoid and olecranon, and loose bodies. Treatment consists of removal of loose bodies and impinging osteophytes along with capsular release. Total elbow arthroplasty is generally contraindicated in younger, active patients who wish to maintain heavy use of the extremity.

Correct Answer: A partial articular-sided supraspinatus tendon avulsion

The images demonstrate a partial articular surface supraspinatus tear (PASTA lesion). The arthroscopic view from the posterior portal shows the articular surface of the supraspinatus with partial tearing. These tears are a common source of shoulder pain and are often amenable to transtendon arthroscopic repair without detachment of the intact bursal surface.

Correct Answer: Osteonecrosis of the femoral head

The radiograph shows a slipped capital femoral epiphysis (SCFE). Closed reduction of a SCFE is contraindicated because it significantly increases the risk of osteonecrosis (avascular necrosis) of the femoral head. The recommended treatment is percutaneous pinning in situ.

Correct Answer: A cellular stroma with plump osteoblasts producing immature woven bone

The clinical presentation, imaging (cortically based lytic lesion with surrounding edema), and histology are diagnostic of an osteoid osteoma. Histologically, it consists of a highly vascularized nidus of interlacing trabeculae of osteoid and woven bone lined by plump, benign osteoblasts.

Correct Answer: Medialization of the hip center of rotation and improvement of anterior and lateral femoral head coverage

The radiograph shows developmental dysplasia of the hip (DDH). The Bernese (Ganz) periacetabular osteotomy is the treatment of choice for symptomatic dysplasia with preserved joint space. Its biomechanical goals include improving anterior and lateral coverage of the femoral head and medializing the hip center of rotation to decrease joint contact forces.

Correct Answer: Young age and open physes

The imaging is classic for an aneurysmal bone cyst (ABC), showing fluid-fluid levels on MRI. Factors associated with a higher rate of local recurrence include young age, open physes, and inadequate surgical margins. The use of a high-speed burr and local adjuvants (like phenol or argon beam) decreases the recurrence rate.

Correct Answer: B

The image demonstrates a Type I superior labrum anterior and posterior (SLAP) lesion, characterized by fraying and degeneration of the superior labrum with an intact biceps anchor. The appropriate treatment for a Type I SLAP lesion is simple arthroscopic debridement. Biceps tenodesis or tenotomy is not indicated because the biceps anchor is stable. Suture anchor repair is reserved for Type II or Type IV SLAP lesions where the biceps anchor is detached.

Correct Answer: C

The image shows a classic Type II SLAP tear, where the superior labrum and biceps anchor are detached from the superior glenoid. In a young, competitive overhead athlete, arthroscopic labral repair yields the highest satisfaction and best chance for return to overhead sports. Labral debridement alone leads to predictably poor results in this demographic. Biceps tenodesis or tenotomy may be considered in older patients or non-overhead athletes with Type II SLAP tears.

Correct Answer: B

The radiographs demonstrate classic hinge abduction in a patient with Legg-Calve-Perthes disease. Hinge abduction occurs when the enlarged, deformed lateral portion of the femoral head impinges on the lateral acetabular margin during abduction, preventing the head from sliding concentrically into the acetabulum. The arthrogram shows medial dye pooling due to distraction of the joint. Persistent hinge abduction prevents proper femoral head remodeling and is an indication for surgical intervention.

Correct Answer: C

The MRI scans demonstrate a lipohemarthrosis, characterized by the layering of fat (superiorly, high signal on T1), serum (centrally), and red blood cells (inferiorly, low signal). The most common cause of a lipohemarthrosis is an intra-articular fracture, which allows marrow fat to escape into the joint space. While an ACL tear can cause a hemarthrosis, it typically does not produce a lipohemarthrosis unless accompanied by an osteochondral fracture.

Correct Answer: A

The images show a partial articular surface supraspinatus tear (PASTA lesion). When these tears involve greater than 50% of the tendon thickness, surgical repair is often indicated. A common and effective technique is a transtendon arthroscopic repair, which secures the articular-sided avulsion while preserving the intact bursal surface of the tendon. Acromioplasty alone does not address the structural tendon defect.

Correct Answer: C

The radiograph demonstrates a slipped capital femoral epiphysis (SCFE) of the left hip. The standard of care for a stable SCFE is percutaneous pinning in situ with a single cannulated screw to prevent further slippage and promote physeal closure. Closed reduction is contraindicated as it significantly increases the risk of osteonecrosis. Spica casting and observation are not appropriate definitive treatments.

Correct Answer: B

The clinical presentation (night pain relieved by NSAIDs), radiographic appearance (cortically based lytic lesion with surrounding sclerosis), and histology (vascular stroma with osteoblasts and woven bone) are diagnostic of an osteoid osteoma. The preferred modern treatment for most osteoid osteomas is CT-guided percutaneous radiofrequency ablation, which is minimally invasive and highly effective. En bloc resection is rarely required today.

Correct Answer: C

The radiograph reveals developmental dysplasia of the hip (DDH) with significant anterolateral undercoverage but preserved joint space. In a young, active patient with symptomatic DDH and minimal osteoarthritis, a Bernese (Ganz) periacetabular osteotomy is the procedure of choice. It reorients the acetabulum to improve femoral head coverage and biomechanics, delaying or preventing the need for total hip arthroplasty.

Correct Answer: C

The histologic description and image are pathognomonic for plasma cells, which characterize multiple myeloma. The cells are round/oval with an eccentric nucleus, prominent nucleolus, and a perinuclear clearing (halo) that represents the prominent Golgi apparatus. Multiple myeloma frequently presents as lytic bone lesions in older adults.

Correct Answer: B

The radiographs show a volar Barton's fracture (volar displaced intra-articular distal radius fracture-dislocation). The most biomechanically sound treatment is an open reduction through a volar approach and stabilization with a volar buttress plate. The buttress plate effectively neutralizes the axial loading and shear forces that drive the volar fragment proximally. A dorsal plate cannot provide this buttress effect for a volar shear fracture.

Correct Answer: B

The image and clinical description are consistent with a Type I SLAP lesion, which is characterized by degenerative fraying of the superior labrum with an intact biceps anchor. The appropriate treatment for a Type I SLAP lesion is simple arthroscopic debridement of the frayed tissue. Repair or tenodesis is not indicated because the biceps anchor remains stable and intact.

Correct Answer: C

The MRI demonstrates lipohemarthrosis, characterized by a distinct layering effect in the suprapatellar pouch. Fat (which has high signal intensity on T1-weighted images) layers superiorly, serum layers centrally, and red blood cells layer inferiorly. This finding is highly indicative of an intra-articular fracture, which allows marrow fat to escape into the joint space.

Correct Answer: B

The widened teardrop distance (a difference of >2 mm compared to the contralateral side) indicates a significant joint effusion. In a child presenting with refusal to bear weight and limited motion, septic arthritis must be urgently ruled out. Hip aspiration is the most definitive test to differentiate septic arthritis from transient synovitis by obtaining fluid for cell count, Gram stain, and culture.

Correct Answer: B

The radiograph demonstrates hinge abduction, where the extruded, enlarged lateral portion of the femoral head hinges against the lateral acetabular margin during abduction. This prevents the femoral head from seating concentrically in the acetabulum, thereby preventing the acetabulum from acting as a spherical mold to remodel the femoral head during the healing phase of Legg-Calve-Perthes disease.

Correct Answer: C

The patient has primary degenerative arthritis of the elbow, characterized by osteophytes on the coronoid and olecranon, loose bodies, and pain at terminal extension. The most appropriate surgical treatment for a high-demand patient (such as a heavy laborer) is the removal of loose bodies, excision of impinging osteophytes, and capsular release (performed either open or arthroscopically). Total elbow arthroplasty is contraindicated in heavy laborers due to strict permanent lifting restrictions.

Correct Answer: B

The patient has congenital scoliosis. Approximately 60% of patients with congenital vertebral anomalies have associated abnormalities in other organ systems. The most common associated extraspinal anomalies are genitourinary (occurring in up to 37% of patients), such as renal agenesis, duplication, or ectopia. Therefore, a renal ultrasound is the most appropriate and least invasive initial screening test.

Correct Answer: B

Recurrent Morton's neuroma is typically due to a stump neuroma located in the weight-bearing area resulting from an initial resection that was too distal. The most reliable surgical treatment is a revision neurectomy to resect the nerve more proximally, moving the stump out of the weight-bearing zone. A plantar approach is preferred for revision surgery as it allows excellent visualization of the nerve proximal to the deep transverse metatarsal ligament and avoids the dorsal scar tissue from the index procedure.

Correct Answer: D

The image shows a Type II SLAP lesion, characterized by detachment of the superior labrum and biceps anchor from the superior glenoid. In a young, competitive overhead athlete, arthroscopic repair of the SLAP lesion using suture anchors is the treatment of choice to restore the stabilizing function of the biceps anchor and allow return to sports. Tenodesis or tenotomy is generally reserved for older patients or those with chronic, degenerative changes.

Correct Answer: C

Isolated or disproportionate loss of external rotation with the arm at the side is the clinical hallmark of a contracted rotator cuff interval, which includes the coracohumeral ligament and the superior glenohumeral ligament. Arthroscopic release of the rotator cuff interval is the treatment of choice when conservative management fails to restore external rotation.

Correct Answer: D

While anatomic (notch width, Q-angle) and hormonal factors have been implicated in the higher rate of ACL tears in females, neuromuscular factors (such as landing biomechanics, decreased hamstring-to-quadriceps strength ratio, and altered muscle activation patterns) are considered the most significant and, importantly, modifiable risk factors. Neuromuscular training programs have been shown to effectively reduce the incidence of ACL tears in female athletes.