Menu

3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 241 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 4801

Topic: Total Hip Arthroplasty (THA)

A 75-year-old male with a history of recurrent THA dislocations secondary to severe abductor deficiency is planned for revision surgery. His acetabular cup is well-fixed and correctly positioned. Which of the following is the most appropriate reconstructive option?

. Exchange to a larger diameter conventional femoral head
. Revision to a constrained acetabular liner
. Revision to a dual-mobility construct
. Advancement of the greater trochanter
. Application of an abduction brace for 12 weeks

Correct Answer & Explanation

. Exchange to a larger diameter conventional femoral head

Explanation

A dual-mobility construct provides excellent stability for patients with recurrent instability and abductor deficiency, boasting lower failure rates than constrained liners. It increases the effective head size and jump distance.

Question 4802

Topic: Total Knee Arthroplasty (TKA)

When utilizing an anterior referencing system during TKA, downsizing the femoral component will result in which of the following gap changes?

. Increased extension gap
. Decreased extension gap
. Increased flexion gap
. Decreased flexion gap
. No change in gaps

Correct Answer & Explanation

. Increased extension gap

Explanation

Anterior referencing bases the cuts off the anterior femoral cortex. Downsizing the femoral component shifts the posterior cut further anteriorly, resecting more posterior condylar bone and thus increasing the flexion gap.

Question 4803

Topic: 3. Adult Reconstruction (Hip & Knee)

A 60-year-old male presents with unilateral hip pain 7 years after a metal-on-polyethylene THA utilizing a large-diameter cobalt-chrome head. Inflammatory markers are normal, but serum cobalt levels are significantly elevated while chromium is normal. What is the most likely diagnosis?

. Polyethylene wear osteolysis
. Periprosthetic joint infection
. Trunnionosis
. Aseptic loosening of the femoral stem
. Delayed metal hypersensitivity

Correct Answer & Explanation

. Polyethylene wear osteolysis

Explanation

Trunnionosis is mechanically assisted crevice corrosion at the head-neck junction. It classically presents with elevated serum cobalt levels disproportionate to chromium in metal-on-polyethylene implants, particularly those utilizing large modular heads.

Question 4804

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old active male underwent a primary total hip arthroplasty using a ceramic-on-ceramic bearing. Three years postoperatively, he complains of an audible squeaking noise from the hip during ambulation, though he is pain-free. What is the most likely risk factor for this phenomenon?

. Implant malpositioning leading to edge loading
. Use of a highly cross-linked polyethylene liner
. Allergic reaction to the titanium stem
. Avascular necrosis of the greater trochanter
. Subsidence of the femoral stem

Correct Answer & Explanation

. Implant malpositioning leading to edge loading

Explanation

Squeaking in ceramic-on-ceramic THA is strongly associated with edge loading caused by component malpositioning (e.g., steep cup inclination or excessive anteversion). Stripe wear is also characteristic of this mechanical complication.

Question 4805

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary posterior-stabilized total knee arthroplasty, the surgeon uses spacer blocks and notes that the knee is well-balanced in extension but tight in flexion. Which of the following is the most appropriate next step to balance the knee?

. Downsize the femoral component
. Release the posterior capsule
. Recut the proximal tibia with more posterior slope
. Increase the thickness of the polyethylene insert
. Resect more distal femur

Correct Answer & Explanation

. Downsize the femoral component

Explanation

A knee that is tight in flexion and balanced in extension requires a reduction in the anteroposterior dimension of the femoral component (downsizing the femur). Increasing the posterior tibial slope can also increase the flexion gap without affecting the extension gap.

Question 4806

Topic: 3. Adult Reconstruction (Hip & Knee)

A 60-year-old male presents with isolated medial compartment osteoarthritis of the knee. Which of the following is a classic contraindication to performing a medial unicompartmental knee arthroplasty (UKA) in this patient?

. Age greater than 60 years
. Anterior cruciate ligament (ACL) deficiency
. Weight greater than 80 kg
. Chondrocalcinosis without clinical inflammatory arthritis
. Mild patellofemoral osteoarthritis

Correct Answer & Explanation

. Age greater than 60 years

Explanation

An intact ACL is traditionally considered a prerequisite for medial UKA, as ACL deficiency leads to altered kinematics and early failure. Age, weight, and asymptomatic patellofemoral arthritis are no longer considered absolute contraindications.

Question 4807

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year-old female presents with a painful total knee arthroplasty 3 years postoperatively. Synovial fluid analysis reveals an elevated alpha-defensin level. What is the biological function of the molecule being measured?

. It is a pro-inflammatory cytokine released by macrophages
. It is an antimicrobial peptide released by neutrophils
. It is an acute-phase reactant produced by the liver
. It is an enzyme that degrades bacterial cell walls
. It is an antibody produced by B-lymphocytes

Correct Answer & Explanation

. It is a pro-inflammatory cytokine released by macrophages

Explanation

Alpha-defensin is a biomarker with high sensitivity and specificity for periprosthetic joint infection. It is an antimicrobial peptide secreted by neutrophils in response to pathogens.

Question 4808

Topic: 3. Adult Reconstruction (Hip & Knee)

A 78-year-old female with a history of a cementless total hip arthroplasty falls and sustains a periprosthetic femoral fracture. Radiographs show a fracture around the tip of the stem with subsidence of the component, but the proximal femoral bone stock remains adequate. According to the Vancouver classification, what is the most appropriate management?

. Open reduction and internal fixation with cables alone
. Open reduction and internal fixation with a locking plate and cables
. Revision to a long cementless diaphyseal-engaging stem
. Revision with a proximal femoral replacement
. Cortical strut allografting alone

Correct Answer & Explanation

. Revision to a long cementless diaphyseal-engaging stem

Explanation

This is a Vancouver B2 fracture (fracture around the stem, loose stem, adequate bone stock). The standard of care is revision arthroplasty using a long extensively porous-coated or fluted tapered diaphyseal-engaging stem.

Question 4809

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old male with a metal-on-polyethylene total hip arthroplasty presents with new-onset groin pain 5 years postoperatively. Serum cobalt and chromium levels are significantly elevated, and MRI demonstrates a solid/cystic pseudotumor. What is the most likely source of the metal ions?

. Bearing surface wear
. Mechanically assisted crevice corrosion at the head-neck junction
. Galvanic corrosion between the cup and screws
. Fretting at the stem-cement interface
. Impingement of the femoral neck on the acetabular rim

Correct Answer & Explanation

. Mechanically assisted crevice corrosion at the head-neck junction

Explanation

In a metal-on-polyethylene THA with elevated metal ions and a pseudotumor, the source is typically trunnionosis. This involves mechanically assisted crevice corrosion at the modular head-neck junction.

Question 4810

Topic: 3. Adult Reconstruction (Hip & Knee)
Highly cross-linked polyethylene (HXLPE) was developed to reduce wear rates in total hip arthroplasty. Which of the following material properties is most significantly decreased as a result of the irradiation and remelting process used to create HXLPE?
. Oxidation resistance
. Fatigue strength
. Wear resistance
. Elastic modulus
. Crystallinity

Correct Answer & Explanation

. Wear resistance

Explanation

The high-dose irradiation used to cross-link polyethylene significantly improves wear resistance but decreases its mechanical properties, including fatigue strength and yield strength. Remelting or annealing is used to eliminate free radicals and improve oxidation resistance.

Question 4811

Topic: Total Hip Arthroplasty (THA)

In total hip arthroplasty, increasing the femoral offset without changing the leg length or neck-shaft angle has which of the following biomechanical effects?

. Increases the joint reaction force
. Decreases the tension on the abductor musculature
. Decreases the risk of sciatic nerve palsy
. Increases the risk of component impingement
. Decreases the bending moment on the femoral stem

Correct Answer & Explanation

. Increases the joint reaction force

Explanation

Increasing femoral offset increases the lever arm of the abductor muscles, thereby decreasing the force required by the abductors and reducing the overall joint reaction force. However, it does increase the bending moment on the femoral stem.

Question 4812

Topic: 3. Adult Reconstruction (Hip & Knee)

During a direct anterior approach for a total hip arthroplasty, an intern retracts the tensor fasciae latae laterally and the sartorius medially. A nerve running over the anterior aspect of the thigh is inadvertently injured. This nerve originates from which nerve roots?

. L1-L2
. L2-L3
. L3-L4
. L4-L5
. L5-S1

Correct Answer & Explanation

. L2-L3

Explanation

The lateral femoral cutaneous nerve (LFCN) is at risk during the direct anterior approach to the hip. It originates from the L2 and L3 nerve roots of the lumbar plexus.

Question 4813

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old female is 1 year out from a posterior-stabilized (PS) total knee arthroplasty. She complains of a painful catching and popping sensation in the anterior knee when extending from a flexed position. What is the most likely etiology?

. Loose patellar component
. Fibrous nodule at the superior pole of the patella engaging the intercondylar box
. Overhanging medial border of the tibial tray
. Popliteus tendon impingement
. Rupture of the quadriceps tendon

Correct Answer & Explanation

. Fibrous nodule at the superior pole of the patella engaging the intercondylar box

Explanation

Patellar clunk syndrome is most commonly associated with older PS knee designs. It is caused by the formation of a fibrous nodule at the superior pole of the patella that catches in the femoral intercondylar box during active extension.

Question 4814

Topic: 3. Adult Reconstruction (Hip & Knee)
A patient undergoing revision total hip arthroplasty has massive acetabular bone loss. Intraoperative assessment reveals pelvic discontinuity, and the superior rim of the acetabulum is absent with greater than 3 cm of superomedial component migration. Which Paprosky classification best describes this defect?
. Type I
. Type IIA
. Type IIB
. Type IIIA
. Type IIIB

Correct Answer & Explanation

. Type IIIB

Explanation

Paprosky Type IIIB defects involve severe destruction of the acetabular rim, >3 cm of superomedial migration, and pelvic discontinuity. Management often requires complex constructs like a cup-cage or custom triflange.

Question 4815

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old male presents with inability to perform a straight leg raise 3 months following a primary total knee arthroplasty. Imaging demonstrates an avulsion of the patellar tendon from the tibial tubercle. What is the most reliable surgical management for this complication?

. Primary end-to-end repair with nonabsorbable sutures
. Repair augmented with semitendinosus autograft
. Reconstruction using a synthetic mesh or extensor mechanism allograft
. Patellectomy
. Hinged knee brace locked in extension for 12 weeks

Correct Answer & Explanation

. Reconstruction using a synthetic mesh or extensor mechanism allograft

Explanation

Chronic or post-TKA patellar tendon avulsions have a high failure rate with primary repair. Reconstruction with a synthetic mesh (e.g., Marlex) or a complete extensor mechanism allograft is the preferred and most reliable treatment.

Question 4816

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient is undergoing a total knee arthroplasty for a severe valgus deformity. During the surgical exposure and balancing, a structure is injured leading to a postoperative foot drop. At what specific step of the procedure is this nerve at highest risk of injury?

. Correction of the valgus deformity during IT band and posterolateral capsule release
. Resection of the anterior cruciate ligament
. Resection of the posterior cruciate ligament
. Placement of the medial retractor
. Cementing of the patellar component

Correct Answer & Explanation

. Correction of the valgus deformity during IT band and posterolateral capsule release

Explanation

The common peroneal nerve is at highest risk of injury during the correction of severe valgus deformities, particularly during the release of the iliotibial band and posterolateral capsule, or due to traction postoperatively.

Question 4817

Topic: Total Hip Arthroplasty (THA)

A 75-year-old patient with Parkinson's disease and abductor deficiency experiences recurrent posterior dislocations following a primary THA. A revision to a constrained acetabular liner is planned. What is the most critical prerequisite for the successful use of a constrained liner?

. Use of a highly cross-linked polyethylene liner
. Use of a 36-mm or larger femoral head
. Excellent bone ingrowth and stable fixation of the acetabular shell
. Preservation of the short external rotators
. Use of a dual-mobility construct

Correct Answer & Explanation

. Excellent bone ingrowth and stable fixation of the acetabular shell

Explanation

Constrained liners transfer significant forces to the bone-implant interface. Therefore, a well-fixed, osseointegrated acetabular shell is an absolute prerequisite to prevent catastrophic failure and cup loosening.

Question 4818

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient with a metal-on-metal total hip arthroplasty presents with a large fluid collection and tissue necrosis around the hip joint. Histological examination of the periprosthetic tissue is most likely to show:

. Abundant neutrophils and bacteria
. Aseptic, lymphocyte-dominated vasculitis-associated lesions (ALVAL)
. Massive foreign body giant cell reaction to polyethylene particles
. Granulomas with caseating necrosis
. Malignant spindle cells

Correct Answer & Explanation

. Aseptic, lymphocyte-dominated vasculitis-associated lesions (ALVAL)

Explanation

Adverse local tissue reactions (ALTR) or ALVAL in metal-on-metal implants are characterized histologically by a diffuse perivascular lymphocytic infiltrate, tissue necrosis, and minimal to no polyethylene particles.

Question 4819

Topic: Total Hip Arthroplasty (THA)

A patient complains of the operative leg feeling "too long" immediately following a THA. Radiographs show the tip of the greater trochanter is perfectly aligned with the center of the femoral head, but the lesser trochanter is 15 mm distal to the ischial tuberosity compared to the contralateral side. The femoral offset is symmetric. What error occurred intraoperatively?

. The femoral neck cut was made too low
. An excessively long modular head was chosen
. The acetabular cup was placed too far superiorly
. The acetabular cup was placed too inferiorly
. The femoral stem was placed in varus

Correct Answer & Explanation

. The acetabular cup was placed too inferiorly

Explanation

If the relationship between the greater trochanter and the center of rotation is maintained, but the femur is distally displaced relative to the pelvis (lesser trochanter to ischial tuberosity), the acetabular component was placed too inferiorly, lowering the center of rotation and lengthening the leg.

Question 4820

Topic: 3. Adult Reconstruction (Hip & Knee)

In mechanically aligned total knee arthroplasty, the distal femoral cut is typically made at what angle relative to the intramedullary axis of the femur?

. Perpendicular to the mechanical axis (approx. 5-7 degrees of valgus to the anatomic axis)
. Perpendicular to the anatomic axis (0 degrees of valgus)
. 3 degrees of varus
. 10 degrees of valgus
. Parallel to the epicondylar axis

Correct Answer & Explanation

. Perpendicular to the mechanical axis (approx. 5-7 degrees of valgus to the anatomic axis)

Explanation

In standard mechanical alignment for TKA, the distal femoral cut is made perpendicular to the mechanical axis. Since the mechanical axis typically diverges from the anatomic axis by 5-7 degrees, a 5-7 degree valgus cut relative to the intramedullary (anatomic) axis is utilized.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page