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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 251 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 5001

Topic: 3. Adult Reconstruction (Hip & Knee)

Optimizing modifiable risk factors prior to total joint arthroplasty significantly reduces the risk of periprosthetic joint infection (PJI) and wound complications. According to current American Association of Hip and Knee Surgeons (AAHKS) guidelines, what are the recommended preoperative thresholds for HbA1c and serum albumin in an elective total joint replacement?

. HbA1c < 8.5% and Albumin > 3.0 g/dL
. HbA1c < 7.0% and Albumin > 3.5 g/dL
. HbA1c < 9.0% and Albumin > 2.5 g/dL
. HbA1c < 6.0% and Albumin > 4.5 g/dL
. HbA1c < 7.5% and Albumin < 3.0 g/dL

Correct Answer & Explanation

. HbA1c < 8.5% and Albumin > 3.0 g/dL

Explanation

Preoperative medical optimization is critical. Poor glycemic control (HbA1c > 7.0% or 7.5% depending on specific institutional protocols, but strictly > 7.0% is widely cited for highest risk reduction) and malnutrition (serum albumin < 3.5 g/dL, transferrin < 200 mg/dL, or total lymphocyte count < 1500 cells/mm3) are strong independent risk factors for surgical site infection and delayed wound healing. The standard accepted minimum thresholds are HbA1c < 7.0% and Albumin > 3.5 g/dL.

Question 5002

Topic: Total Knee Arthroplasty (TKA)

A 70-year-old female presents with an inability to actively extend her knee 6 months following a primary total knee arthroplasty. Clinical examination and imaging confirm a chronic disruption of the extensor mechanism at the mid-substance of the patellar tendon. The components are well-fixed without evidence of infection. What is the most reliable reconstructive option for this chronic failure?

. Primary end-to-end repair using heavy non-absorbable sutures
. Reconstruction using synthetic mesh (e.g., Marlex) or extensor mechanism allograft
. Total patellectomy
. Immobilization in a hinged knee brace locked in extension for 12 weeks
. Medial gastrocnemius rotational flap with split-thickness skin graft

Correct Answer & Explanation

. Primary end-to-end repair using heavy non-absorbable sutures

Explanation

Extensor mechanism disruption after TKA is a catastrophic complication. Primary repair of chronic disruptions yields unacceptably high failure rates due to poor tissue quality and tension. The standard of care for chronic patellar tendon ruptures in the setting of TKA is reconstruction using an extensor mechanism allograft (tibial tubercle, patellar tendon, patella, quad tendon) or synthetic mesh (e.g., Marlex mesh), which acts as a scaffold for fibrous tissue ingrowth.

Question 5003

Topic: 3. Adult Reconstruction (Hip & Knee)
A patient with a documented severe metal allergy is scheduled for a primary total knee arthroplasty. If the patient has a true hypersensitivity reaction to standard orthopedic implants, which of the following best describes the pathophysiologic mechanism and the most common offending metal?
. Type I IgE-mediated anaphylactic reaction; Titanium
. Type III immune-complex mediated reaction; Aluminum
. Type IV cell-mediated delayed hypersensitivity; Nickel
. Type II cytotoxic hypersensitivity; Cobalt
. Type IV cell-mediated delayed hypersensitivity; Vanadium

Correct Answer & Explanation

. Type IV cell-mediated delayed hypersensitivity; Nickel

Explanation

Metal hypersensitivity in total joint arthroplasty is a Type IV cell-mediated (delayed) hypersensitivity reaction. It is mediated by T-lymphocytes rather than antibodies. The most common metal sensitizers in the general population, and historically the culprits in symptomatic orthopedic implants (specifically stainless steel or cobalt-chrome alloys), are Nickel, Cobalt, and Chromium. Nickel is the most prevalent contact allergen overall.

Question 5004

Topic: 3. Adult Reconstruction (Hip & Knee)
A 75-year-old male sustains a posterior dislocation of his total hip arthroplasty. He reports that his primary surgery was 15 years ago, and he has never had a dislocation prior to this event. Assuming no recent trauma or neurological decline, what is the most common pathophysiologic mechanism for a 'late' (>5 years post-op) THA dislocation?
. Failure of the abductor repair over time
. Progressive component migration leading to retroversion
. Polyethylene wear resulting in a decreased effective head size and increased soft tissue laxity
. Late-onset subclinical periprosthetic joint infection
. Heterotopic ossification acting as a fulcrum

Correct Answer & Explanation

. Polyethylene wear resulting in a decreased effective head size and increased soft tissue laxity

Explanation

Dislocations occurring many years (>5 years) after the index THA are typically caused by gradual wear of the polyethylene liner. Volumetric wear of the liner leads to eccentric positioning of the femoral head within the cup, which decreases the "jump distance" (the effective head size) required for dislocation and concurrently generates capsular and soft tissue laxity (the "dead space" effect). This combination makes the hip progressively unstable.

Question 5005

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary total knee arthroplasty, trial reduction reveals a symmetric extension gap but a flexion gap that is tight both medially and laterally. Which of the following adjustments is the most appropriate next step?

. Resect more distal femur
. Increase the posterior slope of the tibial cut
. Downsize the femoral component using an anterior referencing system
. Release the superficial medial collateral ligament
. Upsize the femoral component

Correct Answer & Explanation

. Resect more distal femur

Explanation

A tight flexion gap with a balanced extension gap implies the anteroposterior dimension of the femoral component is too large. Downsizing the femoral component using anterior referencing increases posterior condylar resection, enlarging the flexion gap without affecting the extension gap.

Question 5006

Topic: 3. Adult Reconstruction (Hip & Knee)

A surgeon is performing a posterior-stabilized total knee arthroplasty. After making the initial bone cuts and inserting trial components, the knee is symmetric and stable in extension, but the flexion gap is unacceptably tight. Which of the following is the most appropriate surgical adjustment to correct this imbalance?

. Increase the posterior slope of the tibial cut
. Upsize the femoral component
. Release the posterior cruciate ligament
. Downsize the femoral component and use a thicker polyethylene insert
. Downsize the femoral component with the same anterior reference

Correct Answer & Explanation

. Increase the posterior slope of the tibial cut

Explanation

A tight flexion gap with a balanced extension gap requires downsizing the femoral component while maintaining the same anterior reference. This selectively increases the flexion gap by reducing the posterior condylar offset without affecting the extension gap.

Question 5007

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old male presents with groin pain three years after a cementless total hip arthroplasty utilizing a metal-on-polyethylene bearing surface. Laboratory workup reveals substantially elevated serum cobalt levels with normal chromium levels. What is the most likely etiology of his symptoms?

. Adverse local tissue reaction due to polyethylene wear
. Mechanocorrosion at the modular head-neck junction
. Galvanic corrosion at the acetabular shell-liner interface
. Aseptic loosening of the femoral stem
. Occult periprosthetic joint infection

Correct Answer & Explanation

. Adverse local tissue reaction due to polyethylene wear

Explanation

Elevated cobalt levels out of proportion to chromium in a metal-on-polyethylene THA is classic for trunnionosis. This represents mechanocorrosion (fretting and crevice corrosion) at the modular head-neck junction.

Question 5008

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary total knee arthroplasty, internal rotation of the tibial component relative to the tibial tubercle will most likely result in which of the following complications?

. Lateral patellar tracking and potential subluxation
. Medial patellar tracking
. Flexion instability
. Patellar clunk syndrome
. Medial collateral ligament avulsion

Correct Answer & Explanation

. Lateral patellar tracking and potential subluxation

Explanation

Internal rotation of the tibial component effectively lateralizes the tibial tubercle relative to the trochlear groove. This increases the Q-angle and leads to lateral patellar tracking, subluxation, or dislocation.

Question 5009

Topic: 3. Adult Reconstruction (Hip & Knee)

A 75-year-old patient reports a new-onset "clunking" sensation and pain in their knee when transitioning from a seated to a standing position, one year after a posterior-stabilized total knee arthroplasty. What is the most likely pathophysiologic mechanism for this finding?

. Impingement of the popliteus tendon on the lateral femoral condyle
. A fibrous nodule on the superior pole of the patella catching in the intercondylar box
. Mid-flexion instability due to an elevated joint line
. Polyethylene wear of the tibial post
. Aseptic loosening of the patellar button

Correct Answer & Explanation

. Impingement of the popliteus tendon on the lateral femoral condyle

Explanation

Patellar clunk syndrome is primarily associated with posterior-stabilized TKA designs. It occurs when a fibrous nodule develops at the superior pole of the patella and catches in the intercondylar notch of the femoral component during extension from a flexed position.

Question 5010

Topic: 3. Adult Reconstruction (Hip & Knee)

A 78-year-old female presents to the emergency department after a low-energy fall. She underwent a cementless primary total hip arthroplasty 8 years ago. Radiographs demonstrate a displaced spiral fracture around the distal aspect of a well-fixed porous-coated femoral stem with excellent surrounding bone stock.

According to the Vancouver classification, what is the most appropriate surgical management?

. Non-operative management with touch-down weight bearing
. Open reduction and internal fixation with cerclage wires and a broad plate
. Revision to an extensively porous-coated long femoral stem
. Revision to a cemented long femoral stem
. Proximal femoral replacement

Correct Answer & Explanation

. Non-operative management with touch-down weight bearing

Explanation

This describes a Vancouver B1 periprosthetic fracture (fracture around a well-fixed stem with good bone stock). The standard of care for a Vancouver B1 fracture is open reduction and internal fixation, typically utilizing plates and cables/screws.

Question 5011

Topic: 3. Adult Reconstruction (Hip & Knee)

When performing a medial parapatellar arthrotomy for a total knee arthroplasty, avoiding injury to the superior lateral geniculate artery is critical to prevent which of the following complications?

. Avascular necrosis of the patella
. Pes anserinus bursitis
. Patellar clunk syndrome
. Post-operative hemarthrosis
. Common peroneal nerve palsy

Correct Answer & Explanation

. Avascular necrosis of the patella

Explanation

The superior lateral geniculate artery is a major blood supply to the patella. Sacrificing it during a medial parapatellar approach, which already disrupts medial vessels, significantly increases the risk of patellar avascular necrosis.

Question 5012

Topic: 3. Adult Reconstruction (Hip & Knee)

A surgeon is evaluating a 60-year-old male for a revision total hip arthroplasty due to aseptic loosening. The surgeon plans to utilize a highly porous, uncemented hemispherical acetabular component to achieve a stable center of rotation. Moving the hip center of rotation medially and inferiorly accomplishes which of the following biomechanical advantages?

. Decreases the abductor moment arm and increases joint reaction force
. Increases the abductor moment arm and decreases joint reaction force
. Increases the body weight moment arm
. Increases the risk of sciatic nerve palsy
. Decreases femoral offset without affecting tissue tension

Correct Answer & Explanation

. Decreases the abductor moment arm and increases joint reaction force

Explanation

Medializing the center of rotation decreases the body weight moment arm, while inferior placement helps restore the abductor moment arm. Together, these alterations significantly decrease the overall joint reaction force on the hip.

Question 5013

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary total knee arthroplasty, a surgeon notes that the joint is balanced in both flexion and extension, but there is significant opening on the medial side at 45 degrees of flexion. What is the most likely cause of this mid-flexion instability?

. Undersized femoral component
. Elevation of the joint line
. Excessive distal femoral resection
. Internal rotation of the femoral component
. Avulsion of the superficial medial collateral ligament

Correct Answer & Explanation

. Undersized femoral component

Explanation

Mid-flexion instability (instability between 30 and 60 degrees despite stability in extension and 90 degrees flexion) is most commonly caused by elevation of the joint line. This alters the tension of the collateral ligaments in the mid-flexion arc.

Question 5014

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year-old patient with a history of a metal-on-metal total hip arthroplasty presents with a large symptomatic pseudotumor. Histological examination of the periprosthetic tissue is most likely to demonstrate which of the following patterns?

. Abundant acute neutrophilic infiltrate with fibrin exudation
. Perivascular lymphocytic infiltrate and prominent macrophages
. Sheet-like histiocytic reaction with abundant polyethylene wear debris
. Granulomatous inflammation with caseating necrosis
. Predominant eosinophilic infiltrate with mast cell degranulation

Correct Answer & Explanation

. Abundant acute neutrophilic infiltrate with fibrin exudation

Explanation

Adverse local tissue reaction (ALTR) or ALVAL in metal-on-metal hips is characterized histologically by a perivascular lymphocytic infiltrate (type IV delayed hypersensitivity) and macrophages containing metal debris.

Question 5015

Topic: 3. Adult Reconstruction (Hip & Knee)
In the setting of a revision total knee arthroplasty, the surgeon identifies an Anderson Orthopaedic Research Institute (AORI) Type III bone defect of the proximal tibia. What is the defining characteristic of this defect and the most appropriate reconstructive option?
. Intact metaphyseal bone; standard revision stem
. Deficient metaphyseal bone not compromising the collateral ligament attachments; highly porous cones
. Deficient metaphyseal bone compromising a single condyle; structural allograft
. Deficient metaphyseal bone comprising the entire plateau with compromised collateral ligament attachments; structural allograft or custom implant
. Deficient epiphyseal bone only; cement with screws

Correct Answer & Explanation

. Deficient metaphyseal bone comprising the entire plateau with compromised collateral ligament attachments; structural allograft or custom implant

Explanation

AORI Type III defects involve severe bone loss that compromises a major portion of the condyle or plateau and frequently includes disruption of the collateral ligament attachments. Reconstruction often requires massive structural allografts, custom mega-prostheses, or hinged designs.

Question 5016

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following scenarios is an absolute indication for using a linked (rotating hinge) prosthesis in a revision total knee arthroplasty?

. Isolated anterior cruciate ligament deficiency
. Complete global deficiency of the medial collateral ligament
. AORI Type I distal femoral bone defect
. Fixed valgus deformity of 15 degrees
. Rupture of the posterior cruciate ligament

Correct Answer & Explanation

. Isolated anterior cruciate ligament deficiency

Explanation

A completely deficient or incompetent medial collateral ligament cannot be managed with a constrained non-hinged (CCK) implant because the varus-valgus constraint is insufficient. It mandates a linked or rotating hinge prosthesis to provide adequate coronal plane stability.

Question 5017

Topic: Total Hip Arthroplasty (THA)

During the posterior approach to the hip, protecting the blood supply to the femoral head in the setting of a femoral neck fracture is not required; however, understanding the vascular anatomy is critical to limit bleeding. The medial femoral circumflex artery (MFCA) provides the primary blood supply to the head. Where is the deep branch of the MFCA anatomically located during this approach?

. Superficial to the piriformis tendon
. Between the superior gemellus and the obturator internus
. Between the quadratus femoris and the obturator externus
. Deep to the gluteus minimus muscle belly
. Within the ligamentum teres

Correct Answer & Explanation

. Superficial to the piriformis tendon

Explanation

The deep branch of the medial femoral circumflex artery passes consistently between the pectineus and iliopsoas, then courses posteriorly between the quadratus femoris and obturator externus muscles. Surgeons must be cautious when releasing the quadratus femoris to avoid brisk bleeding.

Question 5018

Topic: 3. Adult Reconstruction (Hip & Knee)

A surgeon is evaluating a painful total knee arthroplasty (TKA) utilizing the 2018 Musculoskeletal Infection Society (MSIS) criteria. Which of the following isolated laboratory findings is considered a major criterion, diagnosing a periprosthetic joint infection outright?

. Serum CRP > 10 mg/L
. Synovial fluid WBC > 3,000 cells/uL
. Positive alpha-defensin test in synovial fluid
. A single positive intra-operative tissue culture
. Presence of a sinus tract communicating with the joint

Correct Answer & Explanation

. Serum CRP > 10 mg/L

Explanation

Under the 2018 MSIS/ICM criteria, the two major criteria that definitively diagnose a periprosthetic joint infection are a sinus tract communicating with the joint or two positive periprosthetic cultures with phenotypically identical organisms.

Question 5019

Topic: Total Hip Arthroplasty (THA)

When templating for a total hip arthroplasty, the surgeon notes an anticipated leg length discrepancy. Lowering the center of rotation of the acetabular component without changing the femoral neck cut or stem size will result in which of the following?

. Increased leg length and increased femoral offset
. Increased leg length without changing femoral offset
. Decreased leg length and decreased femoral offset
. Decreased leg length without changing femoral offset
. No change in leg length or offset

Correct Answer & Explanation

. Increased leg length and increased femoral offset

Explanation

Lowering (inferiorizing) the acetabular center of rotation pushes the entire femur distally, thereby increasing leg length. It does not alter the horizontal distance (femoral offset) between the center of rotation and the femoral axis.

Question 5020

Topic: 3. Adult Reconstruction (Hip & Knee)

A 60-year-old female presents with acute pain and inability to actively extend her knee 3 weeks after a primary total knee arthroplasty. Examination reveals a palpable gap at the superior pole of the patella. What is the most appropriate management strategy?

. Immobilization in a cylinder cast for 6 weeks
. Direct end-to-end repair of the tendon with non-absorbable sutures
. Repair augmented with a synthetic mesh or allograft and tension band wiring
. Revision total knee arthroplasty with a hinged prosthesis
. Physical therapy focusing on quadriceps strengthening

Correct Answer & Explanation

. Immobilization in a cylinder cast for 6 weeks

Explanation

Quadriceps tendon ruptures following TKA generally require operative intervention. Due to poor tissue quality and high failure rates of primary repair, augmentation with synthetic mesh or allograft is the standard of care to achieve a stable reconstruction.

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