OITE & AAOS Board Review MCQs: Arthroplasty & Ankle

Question 1

A 65-year-old male presents with severe groin pain and swelling 8 years after a metal-on-metal total hip arthroplasty. Imaging demonstrates a large cystic mass compressing the femoral vein. Blood cobalt and chromium levels are markedly elevated. Aspiration yields fluid negative for infection. What is the most appropriate definitive management for this patient?

Explanation

This patient has an adverse local tissue reaction (ALTR) or pseudotumor secondary to a metal-on-metal bearing. The definitive treatment for a symptomatic pseudotumor with elevated metal ions and a negative infection workup is revision arthroplasty to a non-metal-on-metal bearing (such as ceramic-on-polyethylene) combined with an extensive synovectomy to remove all necrotic and metallotic tissue.

Question 2

A 70-year-old female complains of knee swelling and a sense of instability when rising from a chair or descending stairs 1 year after a primary posterior-stabilized total knee arthroplasty. On physical examination, she lacks varus or valgus laxity in full extension, but demonstrates a positive anterior and posterior drawer test when the knee is flexed to 90 degrees. Radiographs show well-fixed components with no evidence of loosening. What is the most likely technical error leading to this complication?

Explanation

The patient's presentation of instability specifically in flexion (with stability in extension) is classic for isolated flexion instability. This typically occurs when the flexion gap is disproportionately larger than the extension gap. The most common technical error causing this is undersizing the anteroposterior (AP) dimension of the femoral component, which results in an excessive flexion gap. Excessive distal femoral resection would increase the extension gap, leading to extension instability.

Question 3

A 60-year-old male with end-stage post-traumatic ankle osteoarthritis is being evaluated for surgical options. Which of the following conditions is considered an absolute contraindication to a total ankle arthroplasty (TAA)?

Explanation

Active Charcot neuroarthropathy, neuromuscular disease resulting in absent motor function or sensation, avascular necrosis of the talar body (greater than 50%), and active infection are considered absolute contraindications to total ankle arthroplasty. Concomitant subtalar arthritis can be addressed with a subtalar arthrodesis. While obesity and younger age are relative considerations, they are not absolute contraindications.

Question 4

During a direct anterior approach for a total hip arthroplasty, the surgeon dissects through the superficial internervous plane. Which two nerves supply the muscles that define this specific interval?

Explanation

The direct anterior (Smith-Petersen) approach utilizes a true internervous plane. Superficial dissection occurs between the sartorius (innervated by the femoral nerve) and the tensor fasciae latae (innervated by the superior gluteal nerve). The deep interval is between the rectus femoris (femoral nerve) and the gluteus medius (superior gluteal nerve).

Question 5

A 68-year-old female presents with recurrent posterior dislocations of her primary total hip arthroplasty. CT evaluation demonstrates the acetabular component is positioned in 10 degrees of anteversion and 35 degrees of abduction. The uncemented femoral component is fixed in 5 degrees of retroversion. What is the most appropriate surgical strategy to restore stability?

Explanation

Combined anteversion (the sum of acetabular anteversion and femoral anteversion) is critical for hip stability. The widely accepted safe zone for combined anteversion is between 25 and 45 degrees. In this patient, the combined anteversion is 10 + (-5) = 5 degrees, which places her at high risk for posterior dislocation due to excessive retroversion of the overall construct. The correct strategy is to increase both acetabular and femoral anteversion (e.g., via revision) to achieve proper combined anteversion.

Question 6

A 55-year-old female undergoes a total ankle arthroplasty via a standard anterior approach. Three months postoperatively, she reports numbness over the dorsum of her foot. During the surgical exposure, the extensor digitorum longus (EDL) was retracted laterally. Which cutaneous nerve was most likely injured or stretched during this dissection?

Explanation

The superficial peroneal nerve (specifically its intermediate dorsal cutaneous branch) frequently crosses the anterior surgical field from lateral to medial and is at high risk of injury during the anterior approach to the ankle. It is typically identified and retracted laterally with the extensor digitorum longus. The deep peroneal nerve lies deep to the extensor retinaculum between the extensor hallucis longus and tibialis anterior.

Question 7

A 65-year-old male who underwent a posterior-stabilized total knee arthroplasty 8 months ago complains of a catching sensation and an audible 'clunk' at the superior pole of the patella as his knee extends from 40 degrees to 30 degrees of flexion. Which specific implant design characteristic is most strongly associated with the development of this condition?

Explanation

Patellar clunk syndrome is most commonly associated with posterior-stabilized total knee arthroplasty designs. It occurs when a fibrotic nodule forms at the quadriceps tendon just proximal to the patellar pole, which then catches within the intercondylar box of the femoral component during extension. It is heavily associated with older PS implant designs that feature a high intercondylar box ratio and a sharp superior/anterior margin of the box.

Question 8

During preparation of the proximal femur for an uncemented, tapered-wedge total hip arthroplasty stem, the surgeon notes a non-displaced longitudinal fracture of the calcar propagating 2 cm distal to the lesser trochanter. The broach remains axially and rotationally stable within the canal. What is the most appropriate next step in management?

Explanation

Intraoperative non-displaced calcar fractures during broaching for an uncemented stem are a known complication. If the fracture is recognized early, non-displaced, and the broach achieves excellent stability, the standard of care is to place prophylactic cerclage wires around the proximal femur (to prevent propagation during final stem impaction) and proceed with the planned uncemented stem.

Question 9

When counseling a patient on the expected outcomes of total ankle arthroplasty (TAA) compared to ankle arthrodesis for end-stage ankle osteoarthritis, which of the following statements is most supported by current literature?

Explanation

Total ankle arthroplasty (TAA) maintains ankle range of motion, which improves sagittal plane gait kinematics and reduces the compensatory stresses on adjacent joints (such as the subtalar and talonavicular joints), thereby lowering the rate of adjacent segment arthritis compared to arthrodesis. However, TAA generally has a higher overall reoperation rate and complication profile over the long term compared to arthrodesis.

Question 10

A 72-year-old female presents with an inability to perform a straight leg raise 3 years after a primary total knee arthroplasty. Imaging demonstrates patella alta and a palpable defect at the tibial tubercle. An extensor mechanism allograft reconstruction is planned. To maximize the likelihood of a successful outcome, at what degree of knee flexion should the allograft be tensioned and fixed?

Explanation

When performing an extensor mechanism allograft reconstruction for a disruption following TKA, it is critical to tension the allograft tightly in full extension (0 degrees). Postoperative stretching and attenuation of the allograft are nearly universal, and tensioning in any degree of flexion will inevitably lead to an extensor lag and clinical failure.

Question 11

According to the 2018 International Consensus Meeting (ICM) criteria, which of the following is considered a definitive major criterion for diagnosing a periprosthetic joint infection?

Explanation

The 2018 MSIS/ICM criteria define a periprosthetic joint infection definitively if either of two major criteria are met: (1) A sinus tract communicating with the joint, or (2) Two positive periprosthetic cultures with phenotypically identical organisms. The other options (elevated synovial WBC, positive alpha-defensin, single positive culture, elevated CRP) represent minor criteria that must be combined to generate a diagnostic score.

Question 12

During the medial release of a primary total knee arthroplasty for a varus deformity, the surgeon inadvertently transects the mid-substance of the medial collateral ligament (MCL). The bone cuts have been made, but the components have not yet been implanted. What is the most appropriate intraoperative management strategy?

Explanation

An iatrogenic mid-substance transection of the MCL during TKA requires direct repair. Because the repair alone is insufficient to withstand the coronal plane forces during the healing phase, the construct must be protected by increasing the coronal constraint of the implant. A constrained condylar knee (CCK) prosthesis provides the necessary varus/valgus stability to protect the MCL repair without resorting to the excessive constraint and bone resection of a rotating-hinge device, which is usually reserved for massive bone loss or completely deficient/unrepairable collateral ligaments.

Question 13

A 60-year-old male with a metal-on-polyethylene total hip arthroplasty presents with new-onset groin pain and swelling 7 years postoperatively.

Radiographs show a well-fixed stem and cup. Serum cobalt is 8.5 ppb and chromium is 1.2 ppb. MRI with metal artifact reduction shows a solid pseudotumor. What is the most likely source of the elevated metal ions?

Explanation

In a metal-on-polyethylene THA, elevated cobalt levels that are disproportionately higher than chromium levels are highly indicative of trunnionosis, which is mechanically assisted crevice corrosion and fretting at the modular head-neck taper junction. Because the bearing surface is metal articulating with polyethylene, bearing wear would not produce significant metal ions, but taper corrosion releases massive amounts of cobalt.

Question 14

A 58-year-old patient with end-stage post-traumatic ankle arthritis and a rigid 20-degree coronal plane varus deformity is scheduled for a total ankle arthroplasty (TAA). To minimize the risk of premature implant failure and edge loading, which adjunctive procedure should most likely be performed?

Explanation

A successful TAA requires a plantigrade, well-balanced foot. A rigid varus hindfoot deformity cannot be corrected by the ankle replacement alone and will lead to asymmetric edge loading and early failure of the implant. A lateralizing calcaneal osteotomy (frequently combined with lateral ligament reconstruction or medial release) corrects the hindfoot varus and centers the mechanical axis beneath the tibia.

Question 15

During a primary total knee arthroplasty, the trial reduction reveals that the knee is symmetric and stable in full extension, but excessively tight in 90 degrees of flexion, preventing full range of motion. Which of the following surgical adjustments will most effectively correct this specific imbalance?

Explanation

A knee that is stable in extension but tight in flexion has an isolated tight flexion gap. To increase the flexion gap without altering the extension gap, the surgeon must reduce the posterior condylar offset. This is accomplished by downsizing the femoral component. If an anterior referencing system is used, downsizing reduces the posterior condyles and opens the flexion gap. Resecting more distal femur or releasing the posterior capsule would affect the extension gap.

Question 16

Following a primary total hip arthroplasty performed via a standard posterolateral approach, patients are commonly instructed on 'hip precautions.' Which specific combination of hip movements places the joint at the greatest risk for a posterior dislocation?

Explanation

The posterolateral approach involves dissecting through the posterior capsule and external rotators. Until these structures heal, the hip is most vulnerable to posterior dislocation when the femoral head is driven posteriorly against the weakened capsule. This occurs with a combined mechanism of extreme hip flexion, adduction across the midline, and internal rotation (e.g., crossing the legs while sitting low).

Question 17

The concept of kinematic alignment in total knee arthroplasty has gained popularity in recent years. How does the fundamental goal of kinematic alignment differ from that of traditional mechanical alignment?

Explanation

Traditional mechanical alignment aims for a neutral (0 degree) mechanical axis, cutting the distal femur and proximal tibia perpendicular to their mechanical axes and relying on ligament releases for balancing. Kinematic alignment aims to restore the patient's individual pre-arthritic anatomy, keeping the native joint line obliquity and axes of rotation intact, which theoretically reduces the need for soft tissue releases and improves patient satisfaction.

Question 18

A 55-year-old patient presents with end-stage ankle osteoarthritis and is scheduled for a Total Ankle Arthroplasty (TAA).

Preoperative evaluation includes a weight-bearing CT scan. Which of the following findings on weight-bearing CT would most strongly indicate the need for a concomitant subtalar arthrodesis at the time of the TAA?

Explanation

Total ankle arthroplasty preserves ankle motion, but if the patient has concurrent advanced, symptomatic subtalar osteoarthritis (manifested by severe joint space narrowing, subchondral cysts, and sclerosis), the patient will continue to have significant hindfoot pain postoperatively. Therefore, concomitant end-stage subtalar arthritis is a strong indication to perform a combined TAA and subtalar arthrodesis.

Question 19

A 72-year-old female is undergoing preoperative planning for a total hip arthroplasty. She has a history of a multisegmental lumbar spinal fusion from L2 to the sacrum, resulting in a 'flatback' deformity and a stiff spine. How should the surgeon adjust the positioning of the acetabular component to minimize the risk of dislocation?

Explanation

Patients with a stiff, fused spine and flatback deformity lack the normal ability to posteriorly tilt their pelvis when moving from a standing to a sitting position. Normally, this posterior pelvic tilt dynamically increases acetabular anteversion to accommodate hip flexion. Because this patient cannot tilt her pelvis, she is at a high risk for anterior bony impingement and subsequent posterior dislocation when sitting. To compensate for the stiff spine, the surgeon should implant the cup in greater baseline anteversion and inclination.

Question 20

A 68-year-old male with a BMI of 40 presents with severe, start-up knee pain 5 years after a primary cemented total knee arthroplasty. Radiographs demonstrate continuous, progressive radiolucent lines measuring 3 mm in all zones surrounding the tibial component. The femoral and patellar components appear well-fixed. ESR, CRP, and a joint aspiration are entirely normal, ruling out infection. What is the most appropriate surgical management?

Explanation

This patient has classic radiographic and clinical signs of aseptic loosening of the tibial component. In the absence of infection (normal labs and aspirate) and with a demonstrably well-fixed and well-positioned femoral component, an isolated revision of the loose tibial component (along with a new polyethylene liner compatible with the retained femur) is the treatment of choice, limiting morbidity compared to a full revision.

Question 21

A 62-year-old male undergoes a primary total ankle arthroplasty (TAA). Postoperatively, he develops severe medial gutter pain. Radiographs demonstrate impingement between the talar component and the medial malleolus. Which technical error during the index procedure is the most likely cause of this complication?

Explanation

Internal rotation of the tibial component causes the talus to externally rotate relative to the mortise, leading to impingement of the talar component on the medial malleolus. Proper rotational alignment is critical to avoid gutter impingement in TAA.

Question 22

A 68-year-old woman presents with persistent, loud squeaking from her hip 3 years after a ceramic-on-ceramic total hip arthroplasty (THA). Radiographs show well-fixed components with no evidence of osteolysis. Which of the following component positionings is most strongly associated with this complication?

Explanation

Squeaking in ceramic-on-ceramic THA is heavily associated with edge loading. Edge loading typically occurs when the acetabular component is placed in excessive inclination (e.g., >50 degrees) or excessive anteversion.

Question 23

During a primary posterior-stabilized total knee arthroplasty (TKA), the surgeon evaluates the gaps and notes the knee is unacceptably tight in flexion but symmetric and perfectly balanced in extension. Which of the following is the most appropriate next step to balance the knee?

Explanation

Downsizing the femoral component translates the posterior condyles anteriorly, which increases the flexion gap without affecting the extension gap. Maintaining the same polyethylene thickness ensures the extension gap remains balanced.

Question 24

A 75-year-old male with a history of TKA 2 years ago presents with acute onset knee pain and swelling that began 3 days ago following a dental procedure. Aspiration yields a WBC count of 35,000 cells/uL with 92% PMNs. Radiographs show well-fixed components. Which of the following is the most appropriate surgical treatment?

Explanation

Acute hematogenous periprosthetic joint infection (less than 3-4 weeks of symptoms) with well-fixed implants is an appropriate indication for DAIR. Exchanging the modular polyethylene liner is critical for reducing the bacterial biofilm burden.

Question 25

A 68-year-old female presents with an unstable THA. She has dislocated posteriorly 3 times in the past month. Radiographs demonstrate well-fixed implants with the acetabular component at 40 degrees of inclination and 15 degrees of anteversion. The femoral stem is well-fixed in 15 degrees of anteversion. What is the most appropriate surgical intervention?

Explanation

For recurrent instability with acceptable component positioning and well-fixed implants, conversion to a dual-mobility construct is highly effective. It increases the jump distance and the effective head size, reducing dislocation risk.

Question 26

A 55-year-old female presents with severe lateral ankle pain and a rigid hindfoot 5 years after an ORIF of a pilon fracture. She is diagnosed with end-stage post-traumatic ankle arthritis. She has a BMI of 42 and absent protective sensation in a stocking-glove distribution due to diabetes. Which of the following is the most appropriate definitive management?

Explanation

Neuropathy (Charcot risk) and morbid obesity are considered absolute contraindications to total ankle arthroplasty. A tibiotalocalcaneal arthrodesis is the most robust and appropriate option for this patient.

Question 27

A 72-year-old female sustains a periprosthetic femur fracture around a cemented, polished taper-slip stem 6 years after a THA. Radiographs show a spiral fracture at the tip of the stem with subsidence of the stem by 3 cm within the cement mantle. The femoral bone stock is adequate. What is the most appropriate treatment?

Explanation

This is a Vancouver B2 fracture (fracture around a loose stem with adequate bone stock). The gold standard treatment is revision arthroplasty using a long, porous-coated diaphyseal-engaging stem to bypass the fracture.

Question 28

A 60-year-old man undergoes an uncemented THA via a direct anterior approach. Postoperatively, he complains of localized numbness and burning pain over the anterolateral aspect of his thigh. This complication is most likely due to injury to a nerve that courses between which of the following intervals?

Explanation

The lateral femoral cutaneous nerve is highly at risk during the direct anterior approach to the hip. The superficial surgical interval for this approach is between the sartorius and the tensor fasciae latae.

Question 29

During a primary TKA, the surgeon utilizes kinematic alignment principles. Which of the following statements best describes the fundamental goal of kinematic alignment compared to traditional mechanical alignment?

Explanation

Kinematic alignment aims to restore the patient's native constitutional alignment and joint surface orientation. By doing so, it theoretically restores natural ligament tension, thereby minimizing or eliminating the need for soft tissue releases.

Question 30

A 58-year-old male with a history of a metal-on-polyethylene THA 7 years ago presents with spontaneous groin pain. Radiographs show massive osteolysis of the proximal femur. Aspiration reveals fluid with macrophages containing particulate debris. What is the primary biologic mechanism for this osteolysis?

Explanation

Osteolysis in conventional metal-on-polyethylene THA is primarily driven by a biologic response to submicron polyethylene wear particles. Macrophages phagocytose these particles and release osteoclast-activating cytokines like TNF-alpha, IL-1, and IL-6.

Question 31

Which of the following is the most critical anatomical landmark for establishing the proper rotational alignment of the femoral component in a total knee arthroplasty to optimize patellofemoral tracking?

Explanation

Whiteside's line (the anteroposterior axis of the trochlea) and the surgical transepicondylar axis are the most reliable landmarks for setting femoral component rotation. Proper rotation is essential to prevent patellar maltracking and anterior knee pain.

Question 32

A 68-year-old male presents with a Vancouver B1 periprosthetic femur fracture. The surgeon elects to perform an open reduction and internal fixation with a lateral locking plate. To minimize the risk of mechanical failure at the proximal plate construct, what is the recommended minimum plate length extending proximal to the fracture site?

Explanation

Biomechanical studies dictate that for periprosthetic femur fractures, the fixation plate must overlap the well-fixed femoral stem by a minimum of 2 cortical diameters. This reduces the stress riser effect at the tip of the stem.

Question 33

A patient is evaluated for an isolated ankle arthrodesis versus total ankle arthroplasty (TAA). Which of the following long-term kinematic changes is most typically observed following an isolated ankle arthrodesis compared to a successful TAA?

Explanation

Ankle arthrodesis abolishes tibiotalar motion, leading to compensatory increased stresses and motion at adjacent joints. This significantly elevates the long-term risk of developing symptomatic subtalar and talonavicular osteoarthritis.

Question 34

A 62-year-old woman reports anterior knee pain and a painful \"catching\" sensation when extending her knee from a flexed position, 18 months after a posterior-stabilized TKA. On examination, a palpable clunk is felt at 30 degrees of flexion as the knee extends. What is the most likely etiology?

Explanation

Patellar clunk syndrome is caused by a fibrosynovial nodule that forms at the superior pole of the patella. As the knee extends from flexion, this nodule catches in the intercondylar box of the posterior-stabilized femoral component.

Question 35

A 70-year-old male undergoes a primary TKA. In the recovery room, he is noted to have a dense foot drop and numbness over the dorsum of the foot. Which of the following preoperative deformities places the patient at the highest risk for this specific complication?

Explanation

Correction of a severe, fixed valgus deformity can lead to sudden tensioning and stretch of the common peroneal nerve. This makes valgus knees the highest risk profile for postoperative peroneal nerve palsy in TKA.

Question 36

A 50-year-old male presents with severe groin pain 4 years after a THA utilizing a 36-mm metal head on a titanium stem. MRI shows a large fluid collection in the abductor musculature. Serum cobalt levels are markedly elevated, while chromium is normal. What is the most likely diagnosis?

Explanation

Trunnionosis occurs at the modular head-neck junction and is exacerbated by large-diameter metal heads. It typically presents with isolated elevated cobalt levels and an adverse local tissue reaction (ALTR).

Question 37

A 65-year-old male with end-stage medial compartment knee osteoarthritis and a reducible 10-degree varus deformity is scheduled for a unicompartmental knee arthroplasty (UKA). Which of the following represents an absolute contraindication for a traditional fixed-bearing UKA?

Explanation

An intact ACL is required for a fixed-bearing UKA to ensure proper sagittal kinematics and prevent posterior subluxation of the tibia. ACL deficiency leads to accelerated wear and early catastrophic loosening.

Question 38

Which of the following intraoperative surgical techniques most significantly decreases the risk of postoperative dislocation following a primary THA performed via a posterior approach?

Explanation

Enhanced soft tissue repair, specifically the robust reattachment of the posterior capsule and short external rotators, has been definitively shown to significantly reduce the dislocation rate in the posterior approach.

Question 39

A 78-year-old female presents with thigh pain and inability to bear weight after a mechanical fall. She underwent a right total hip arthroplasty (THA) 10 years ago. Radiographs demonstrate a displaced spiral fracture around the femoral stem, which extends just distal to the tip of the prosthesis. The stem has subsided by 1.5 cm compared to prior radiographs, but the distal femoral bone stock remains robust. What is the most appropriate surgical management?

Explanation

This is a Vancouver B2 periprosthetic femur fracture, characterized by a fracture around a loose stem with adequate distal bone stock. The standard of care is revision to a long cementless diaphyseal-engaging (or modular) stem bypassing the fracture by at least 2 cortical diameters.

Question 40

A 68-year-old male complains of knee instability and swelling 18 months following a posterior-stabilized total knee arthroplasty. On examination, the knee is stable in full extension and at 90 degrees of flexion, but exhibits marked laxity to varus and valgus stress at 30 to 45 degrees of flexion. Which of the following technical errors most likely caused this specific pattern of instability?

Explanation

Mid-flexion instability in a TKA typically results from joint line elevation. When the joint line is elevated (often due to excessive distal femoral resection compensated by a thicker polyethylene liner), the collateral ligaments are balanced in extension and 90 degrees of flexion but become lax in mid-flexion.

Question 41

A 62-year-old male with end-stage post-traumatic ankle osteoarthritis and a rigid 15-degree varus deformity is undergoing total ankle arthroplasty (TAA). Intraoperatively, after making the bony cuts and placing trial components, the ankle remains tight medially and fails to correct to a neutral coronal alignment. Which of the following is the most appropriate next step in management?

Explanation

In a varus ankle undergoing TAA, residual medial tightness after bony resection should be addressed with a stepwise soft tissue release. The deep deltoid ligament is the primary tether and must be released to achieve coronal balance and prevent premature edge-loading and implant failure.

Question 42

A 72-year-old male with ankylosing spondylitis and a completely fused lumbopelvic spine is planned for a total hip arthroplasty. His spine is fused in a flattened position, resulting in fixed pelvic retroversion. How does this rigid spinopelvic state alter the risk of dislocation, and what intraoperative adjustment should be considered?

Explanation

In a stiff spine with fixed pelvic retroversion, the pelvis cannot anteriorly tilt when standing, leaving the acetabulum relatively uncovered anteriorly. This creates a high risk of anterior impingement and dislocation in extension, requiring the cup to be placed in less anteversion than standard.

Question 43

A 45-year-old male patient who underwent a ceramic-on-ceramic total hip arthroplasty 5 years ago presents complaining of an audible, high-pitched squeaking noise coming from his hip with every step. He denies pain or instability. What is the most widely recognized biomechanical cause for this phenomenon?

Explanation

Squeaking in ceramic-on-ceramic THA is heavily associated with edge loading, often due to a steeply placed acetabular component or component malposition. Edge loading disrupts the fluid film lubrication and causes localized stripe wear, producing the characteristic noise.

Question 44

A 55-year-old heavy manual laborer with severe end-stage ankle osteoarthritis opts for a tibiotalar arthrodesis over arthroplasty. To optimize his postoperative gait mechanics and minimize adjacent joint arthritis, what is the ideal position for the ankle fusion?

Explanation

The ideal position for ankle arthrodesis is neutral dorsiflexion (0 degrees), slight valgus (5 degrees), and slight external rotation (5 to 10 degrees). This position closely mimics the normal foot progression angle and minimizes the lever arm stress on the midfoot and knee.

Question 45

A 60-year-old female presents with persistent lateral-sided knee pain and a palpable, painful snapping sensation during active flexion 6 months after a primary posterior-stabilized TKA. Radiographs reveal well-fixed, appropriately sized components. Dynamic ultrasound confirms the popliteus tendon snapping over the edge of the femoral component. What is the most appropriate management?

Explanation

Popliteus impingement or snapping over the lateral border of the femoral component can occur post-TKA, especially if the component is slightly oversized or laterally translated. If conservative measures fail, arthroscopic or open release of the popliteus tendon is an effective and definitive treatment.

Question 46

A 55-year-old active male is undergoing a primary total hip arthroplasty. The surgeon is deciding on the optimal bearing surface. Compared to other bearing combinations, which of the following is the most distinct clinical profile of a ceramic-on-ceramic articulation?

Explanation

Ceramic-on-ceramic bearings have the lowest volumetric wear and are highly resistant to scratching. However, they carry a unique risk of squeaking (audible noise) and a rare but devastating risk of catastrophic bearing fracture.

Question 47

During a primary posterior-stabilized total knee arthroplasty, the surgeon performs the initial bone cuts and inserts spacer blocks. The knee is perfectly balanced and stable in full extension, but it is extremely tight and unable to flex past 80 degrees in flexion. Which of the following technical adjustments is the most appropriate next step to balance the knee?

Explanation

A knee that is tight in flexion but balanced in extension requires an increase in the flexion gap only. Downsizing the femoral component (resecting more posterior condylar bone) or increasing the posterior tibial slope will selectively increase the flexion gap.

Question 48

A 62-year-old female with end-stage ankle osteoarthritis is being evaluated for a total ankle arthroplasty (TAA). Which of the following preoperative findings represents an absolute contraindication to performing a TAA?

Explanation

Avascular necrosis involving more than 50% of the talar body is an absolute contraindication to TAA due to the high risk of component subsidence and failure. Other absolute contraindications include active infection, severe Charcot neuroarthropathy, and absent lower extremity sensation.

Question 49

A 68-year-old male undergoes a right total hip arthroplasty. Six months postoperatively, he has experienced three episodes of posterior dislocation while rising from a low chair. Radiographs and CT imaging demonstrate the acetabular cup is positioned in 20 degrees of anteversion and 40 degrees of inclination. The femoral stem is fixed in 10 degrees of retroversion. What is the most appropriate surgical management?

Explanation

The patient has recurrent posterior instability due to a malpositioned (retroverted) femoral stem, while the cup is in acceptable position. The definitive treatment for a well-fixed, retroverted stem causing recurrent instability is revision of the femoral component to restore normal anteversion.

Question 50

A 71-year-old male presents with a 4-day history of acute, severe right knee pain and swelling. He underwent an uncomplicated primary total knee arthroplasty 3 years ago. He recently had a dental extraction 2 weeks prior without prophylactic antibiotics. Joint aspiration yields a synovial fluid WBC count of 85,000 cells/uL with 92% neutrophils. Radiographs show well-fixed components. What is the most appropriate surgical intervention?

Explanation

This is an acute hematogenous periprosthetic joint infection (symptoms < 3 weeks in a previously well-functioning, chronically implanted joint). The standard of care is an open debridement, antibiotics, and implant retention (DAIR) with exchange of the modular polyethylene insert.

Question 51

A surgeon is performing a primary total knee arthroplasty (TKA). During trialing, the extension gap is excessively tight, preventing full extension, but the flexion gap is perfectly balanced. Which of the following is the most appropriate next step to correct this kinematic mismatch?

Explanation

A tight extension gap with a balanced flexion gap indicates that the distal femoral resection is insufficient. Resecting more distal femur will open the extension gap without affecting the flexion gap.

Question 52

A 45-year-old active female undergoes THA with a ceramic-on-ceramic bearing. At 2 years postoperatively, she complains of a loud, reproducible squeaking noise from her hip during normal gait. Which of the following is the most established biomechanical cause for this phenomenon?

Explanation

Squeaking in ceramic-on-ceramic THA is heavily associated with edge loading, typically caused by acetabular component malposition (e.g., steep inclination or excessive anteversion/retroversion). This leads to stripe wear and disruption of fluid-film lubrication.

Question 53

Total ankle arthroplasty (TAA) provides excellent outcomes in appropriately selected patients but relies on specific structural and neurologic prerequisites. Which of the following represents an absolute contraindication for TAA?

Explanation

Severe peripheral neuropathy, such as Charcot arthropathy, is an absolute contraindication for TAA due to the high risk of catastrophic failure, collapse, and dislocation. Ankle arthrodesis is the preferred salvage in these patients.

Question 54

A 72-year-old woman falls and sustains a periprosthetic femur fracture around a cemented polished taper slip stem. Radiographs show a fracture traversing the mid-stem. The stem has subsided by 2 cm, and there is an osteolytic lesion in the proximal femur, but distal diaphyseal bone stock is adequate. How is this classified and best treated?

Explanation

This is a Vancouver B2 fracture, characterized by a fracture around a loose stem with adequate surrounding bone stock. The standard of care is revision arthroplasty using a diaphyseal-engaging stem that bypasses the fracture by at least two cortical diameters.

Question 55

A 68-year-old male presents with the inability to perform a straight leg raise 6 weeks after a primary TKA. Ultrasound confirms a complete mid-substance patellar tendon rupture. What is the most reliable surgical management for this complication?

Explanation

Primary repair of patellar tendon ruptures after TKA has an unacceptably high failure rate. Extensor mechanism reconstruction using an allograft (e.g., Achilles or whole extensor mechanism) or synthetic mesh is the gold standard for restoration of function.

Question 56

A 55-year-old female presents with anterior groin pain 1 year after an uncemented THA. The pain is exacerbated by active hip flexion. Radiographs demonstrate that the acetabular component is placed with 10 degrees of anteversion and overhangs the anterior acetabular rim by 12 mm. Image-guided injection of the psoas bursa temporarily resolves her pain. What is the most appropriate definitive management?

Explanation

While iliopsoas tenotomy is an option for functional impingement, an anterior component overhang greater than 8 mm is a structural cause of psoas impingement. Revision of the malpositioned acetabular cup is required for definitive resolution.

Question 57

A 62-year-old patient with rheumatoid arthritis has severe end-stage ankle osteoarthritis alongside symptomatic, radiographically advanced subtalar arthritis. The patient is undergoing preoperative planning for a total ankle arthroplasty (TAA). What is the recommended management approach for the subtalar joint?

Explanation

Simultaneous TAA and subtalar arthrodesis is a proven, highly successful approach for concomitant severe ankle and subtalar arthritis. It preserves ankle kinematics while resolving subtalar pain and reduces overall patient rehabilitation time.

Question 58

A 65-year-old male presents with a painful, audible "clunk" in his knee when extending from 45 degrees of flexion, 1 year after a posterior-stabilized (PS) TKA. Radiographs show well-fixed components. Which of the following is the primary pathophysiologic cause of this condition?

Explanation

Patellar clunk syndrome occurs primarily in posterior-stabilized TKA when a fibrous nodule forms at the superior pole of the patella. As the knee extends, this nodule catches in the femoral intercondylar box and abruptly snaps out, causing a painful clunk.

Question 59

A 60-year-old male with a metal-on-polyethylene THA presents with a large anterior thigh mass and significantly elevated serum cobalt levels, while chromium levels remain normal. Radiographs demonstrate well-fixed components with a modular femoral head. Aspiration reveals sterile, opaque fluid. What is the most likely etiology?

Explanation

Trunnionosis (mechanochemical corrosion at the head-neck modular taper) characteristically presents with an elevated cobalt-to-chromium ratio. It can cause a severe adverse local tissue reaction (ALTR) or pseudotumor, even in metal-on-polyethylene bearings.

Question 60

A 68-year-old female is 8 weeks post-operative from an uncomplicated primary TKA. Her current range of motion is 10 degrees to 75 degrees despite aggressive, compliant physical therapy. She is medically stable and radiographs show well-aligned components. What is the most appropriate next step in management?

Explanation

Manipulation under anesthesia (MUA) is highly effective for TKA stiffness when performed between 6 and 12 weeks post-operatively. Delaying MUA beyond 12 weeks significantly decreases its success rate due to mature fibrous scar formation.

Question 61

During a standard posterior approach to the hip for a THA, the short external rotators are tagged and reflected over the posterior capsule. Which of the following structures is most at risk of iatrogenic injury if a retractor is placed too aggressively deep and posterior to the acetabulum?

Explanation

The sciatic nerve lies posterior to the external rotators. Retractors placed deep and posterior to the acetabulum, especially without the protection of the reflected external rotators, place the sciatic nerve at direct risk of compression or laceration.

Question 62

A patient complains of anterior knee pain and a sensation of patellar subluxation 1 year after a primary TKA. A computed tomography (CT) scan evaluates component rotation and demonstrates excessive internal rotation of the tibial component. What is the expected biomechanical consequence of a severely internally rotated tibial component on patellar tracking?

Explanation

Internal rotation of the tibial component effectively medializes the tibial tubercle relative to the trochlear groove. This increases the dynamic Q-angle, resulting in increased lateral vector forces and subsequent lateral patellar tracking or subluxation.

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

Orthopedic Surgery Board Review MCQs: Lower Extremity Arthroplasty & Ankle | Part 171

Key Takeaway

Orthopedic Surgery Board Review MCQs: Lower Extremity Arthroplasty & Ankle | Part 171

Chapter Index