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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 78 of 326

This practice set contains high-yield board review questions covering key concepts in 3. Adult Reconstruction (Hip & Knee). Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 1541

Topic: Total Knee Arthroplasty (TKA)

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?

. It aims to resect bone perpendicular to the mechanical axis of the lower limb universally
. It aims to restore the patient's pre-arthritic, patient-specific joint line obliquity and native axes of rotation
. It mandates extensive ligamentous releases to create equal rectangular gaps in all patients
. It requires placing the femoral component in exactly 3 degrees of external rotation relative to the posterior condylar axis
. It focuses primarily on adjusting the tibial slope to match the contralateral knee

Correct Answer & Explanation

. It aims to resect bone perpendicular to the mechanical axis of the lower limb universally

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 1542

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

. Two-stage revision arthroplasty
. Single-stage revision of both the tibial and femoral components
. Isolated single-stage revision of the tibial component with polyethylene exchange
. Isolated exchange of the polyethylene liner only
. Arthroscopic debridement and cementation of the existing tibial tray

Correct Answer & Explanation

. Two-stage revision arthroplasty

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 1543

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

. Acetabular cup anteversion of 15 degrees
. Acetabular cup inclination of 35 degrees
. Acetabular cup anteversion of 25 degrees and inclination of 55 degrees
. Femoral stem retroversion of 10 degrees
. Femoral stem varus alignment

Correct Answer & Explanation

. Acetabular cup anteversion of 15 degrees

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 1544

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

. Release the posterior capsule
. Downsize the femoral component and use a thicker polyethylene insert
. Downsize the femoral component and use the same thickness polyethylene insert
. Recut the distal femur to remove more bone
. Release the superficial medial collateral ligament

Correct Answer & Explanation

. Release the posterior capsule

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 1545

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

. One-stage exchange arthroplasty
. Two-stage exchange arthroplasty
. Debridement, antibiotics, and implant retention (DAIR) with polyethylene exchange
. Knee arthrodesis
. Suppressive oral antibiotic therapy

Correct Answer & Explanation

. One-stage exchange arthroplasty

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 1546

Topic: Total Hip Arthroplasty (THA)

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?

. Revision of the acetabular component to increase anteversion
. Revision of the femoral component to increase anteversion
. Exchange of the modular head to a longer neck length
. Conversion to a dual-mobility articulation
. Application of a hip abduction brace for 12 weeks

Correct Answer & Explanation

. Revision of the acetabular component to increase anteversion

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 1547

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

. Open reduction internal fixation (ORIF) with a locking plate
. Revision to a long cementless diaphyseal-engaging stem
. Proximal femoral replacement
. ORIF with strut allografts
. Nonoperative management in a long-leg cast

Correct Answer & Explanation

. Open reduction internal fixation (ORIF) with a locking plate

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 1548

Topic: Total Hip Arthroplasty (THA)

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?

. Tensor fasciae latae and gluteus medius
. Sartorius and tensor fasciae latae
. Rectus femoris and vastus lateralis
. Adductor longus and gracilis
. Iliopsoas and pectineus

Correct Answer & Explanation

. Tensor fasciae latae and gluteus medius

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 1549

Topic: Total Knee Arthroplasty (TKA)

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?

. Positioning both the femoral and tibial components exactly perpendicular to the mechanical axis
. Restoring the pre-arthritic native joint lines and soft tissue laxity without extensive ligament releases
. Creating a joint line that is strictly perpendicular to the floor during stance phase
. Releasing the medial collateral ligament to correct a fixed varus deformity to neutral
. Under-sizing the tibial component to allow for maximum rotational freedom

Correct Answer & Explanation

. Positioning both the femoral and tibial components exactly perpendicular to the mechanical axis

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 1550

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

. Type IV hypersensitivity reaction to metal ions
. Macrophage-mediated release of TNF-alpha and IL-1 in response to polyethylene wear debris
. Bacterial biofilm formation on the implant surface causing local bone resorption
. Galvanic corrosion at the head-neck junction
. Stress shielding of the proximal femur secondary to a stiff implant

Correct Answer & Explanation

. Type IV hypersensitivity reaction to metal ions

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 1551

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

. The anteroposterior (Whiteside's) line
. The mechanical axis of the femur
. The adductor tubercle
. The fibular head
. The tibial tubercle

Correct Answer & Explanation

. The anteroposterior (Whiteside's) line

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 1552

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

. Aseptic loosening of the tibial tray
. Fibrous nodule formation at the superior pole of the patella
. Polyethylene wear of the tibial post
. Patellar maltracking due to femoral internal rotation
. Overstuffing of the anterior compartment

Correct Answer & Explanation

. Aseptic loosening of the tibial tray

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 1553

Topic: Total Knee Arthroplasty (TKA)

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?

. Fixed varus deformity of 15 degrees
. Fixed valgus deformity of 20 degrees
. Flexion contracture of 10 degrees
. Genu recurvatum of 5 degrees
. Patella alta

Correct Answer & Explanation

. Fixed varus deformity of 15 degrees

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 1554

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

. Metal hypersensitivity to the acetabular cup
. Trunnionosis (mechanically assisted crevice corrosion)
. Polyethylene wear osteolysis
. Periprosthetic joint infection
. Aseptic loosening of the femoral stem

Correct Answer & Explanation

. Metal hypersensitivity to the acetabular cup

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 1555

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

. Age greater than 60 years
. Weight greater than 90 kg
. Anterior cruciate ligament (ACL) deficiency
. Asymptomatic patellofemoral chondromalacia
. Exposed bone in the medial compartment

Correct Answer & Explanation

. Age greater than 60 years

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 1556

Topic: Total Hip Arthroplasty (THA)

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

. Use of a 28-mm femoral head
. Meticulous repair of the posterior capsule and short external rotators
. Preserving the ligamentum teres
. Anteverting the acetabular cup to 50 degrees
. Lengthening the limb by 2 cm

Correct Answer & Explanation

. Use of a 28-mm femoral head

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 1557

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

. Open reduction and internal fixation with a lateral locking plate and cerclage cables
. Revision to a standard length cementless extensively porous-coated stem
. Revision to a long cementless diaphyseal-engaging stem bypassing the fracture
. Cortical strut allografting and cerclage cables without stem revision
. Revision of both the acetabular and femoral components

Correct Answer & Explanation

. Open reduction and internal fixation with a lateral locking plate and cerclage cables

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 1558

Topic: Total Knee Arthroplasty (TKA)

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?

. Undersizing the femoral component
. Excessive posterior tibial slope
. Joint line elevation
. Failure to resurface the patella
. Inadequate release of the posterior cruciate ligament

Correct Answer & Explanation

. Undersizing the femoral component

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 1559

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

. Galvanic corrosion at the trunnion
. Component micro-motion due to aseptic loosening
. Stripe wear from edge loading
. Third-body wear from retained cement
. Impingement of the psoas tendon

Correct Answer & Explanation

. Galvanic corrosion at the trunnion

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 1560

Topic: Total Knee Arthroplasty (TKA)

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?

. Immediate revision to a constrained condylar knee
. Revision of the polyethylene liner to a thicker size
. Open or arthroscopic popliteus tendon release
. Exchange of the femoral component
. Corticosteroid injection into the lateral collateral ligament

Correct Answer & Explanation

. Immediate revision to a constrained condylar knee

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.

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