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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 297 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 5921

Topic: 3. Adult Reconstruction (Hip & Knee)

A TKA patient develops progressively worsening pain and swelling with eventual radiographic evidence of early osteolysis around the tibial component. Which specific malalignment is most strongly implicated in initiating this process?

. Femoral component in 5 degrees of flexion
. Tibial component in 5 degrees of valgus
. Tibial component in 5 degrees of varus
. Femoral component in 3 degrees of internal rotation
. Patellar component tilt

Correct Answer & Explanation

. Tibial component in 5 degrees of varus

Explanation

Tibial component varus malalignment (e.g., 5 degrees of varus) leads to uneven loading and significantly higher stresses on the medial compartment. This accelerates polyethylene wear, producing wear particles that can trigger an inflammatory response and lead to osteolysis, ultimately causing aseptic loosening. Other malalignments can cause pain and dysfunction but are less directly implicated in early osteolysis from accelerated wear than coronal plane malalignment leading to uneven load distribution.

Question 5922

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following describes the functional consequence of restoring the mechanical axis in 7 degrees of valgus in a standard TKA (designed for neutral alignment)?

. Increased polyethylene wear on the medial side
. Increased polyethylene wear on the lateral side
. Increased risk of varus instability
. Patellofemoral tracking issues
. Reduced range of motion in flexion

Correct Answer & Explanation

. Increased polyethylene wear on the lateral side

Explanation

Restoring the mechanical axis in 7 degrees of valgus (i.e., excessive valgus alignment) in a standard TKA shifts the load predominantly to the lateral compartment. This will lead to increased polyethylene wear on the lateral side of the tibial insert, and can also cause medial collateral ligament (MCL) laxity and valgus instability. Varus instability would be caused by varus malalignment. Patellofemoral issues are typically rotational. Reduced range of motion is less directly caused by coronal malalignment.

Question 5923

Topic: Total Knee Arthroplasty (TKA)

What is the clinical significance of a persistent 'quadriceps lag' after TKA, despite good surgical alignment and rehabilitation?

. Suggests patella alta
. Suggests patella baja
. Indicates a potentially overlooked infection
. May be due to persistent flexion contracture or extensor mechanism weakness
. Points to excessive femoral component external rotation

Correct Answer & Explanation

. May be due to persistent flexion contracture or extensor mechanism weakness

Explanation

A persistent quadriceps lag (inability to actively extend the knee fully, even if passive extension is full) after TKA, when alignment is otherwise good, often indicates persistent extensor mechanism weakness (e.g., due to preoperative atrophy, pain, or nerve injury) or a subtle, persistent flexion contracture that is difficult to overcome. It is not directly indicative of patella alta or baja (though these can cause extensor dysfunction), nor an infection or specific rotational error in this general context.

Question 5924

Topic: Total Knee Arthroplasty (TKA)

When using a computer navigation system for TKA, what is the primary benefit regarding component malalignment prevention?

. Eliminates the need for soft tissue releases
. Automatically compensates for severe bone deformities without manual input
. Provides real-time, objective data on bone cuts and component orientation, minimizing manual measurement errors
. Reduces surgical time significantly
. Guarantees a perfectly sterile surgical field

Correct Answer & Explanation

. Provides real-time, objective data on bone cuts and component orientation, minimizing manual measurement errors

Explanation

The primary benefit of computer navigation systems in TKA regarding component malalignment prevention is that they provide real-time, objective data on bone cuts and component orientation. This minimizes manual measurement errors and allows the surgeon to verify and adjust alignment precisely, especially in complex cases, ultimately leading to more accurate component placement. It does not eliminate the need for releases, isn't fully automatic, often increases surgical time, and doesn't guarantee sterility.

Question 5925

Topic: Total Knee Arthroplasty (TKA)

What is the most accurate method to assess the patellar height after TKA?

. Insall-Salvati ratio
. Blackburne-Peel ratio
. Caton-Deschamps index
. Lateral knee radiograph
. All of the above indices on a lateral knee radiograph

Correct Answer & Explanation

. All of the above indices on a lateral knee radiograph

Explanation

All listed indices (Insall-Salvati, Blackburne-Peel, Caton-Deschamps) are commonly used to assess patellar height on a lateral knee radiograph. The choice of index may depend on surgeon preference or specific clinical scenarios, but a true lateral radiograph is essential for applying these measurements accurately. Therefore, 'All of the above indices on a lateral knee radiograph' is the most complete answer.

Question 5926

Topic: 3. Adult Reconstruction (Hip & Knee)

Which factor is most challenging to correct once established post-TKA and can significantly impact long-term outcomes and patient satisfaction?

. Mild postoperative swelling
. Minor incisional pain
. Persistent component rotational malalignment leading to patellofemoral dysfunction
. Transient quadriceps weakness
. Small degree of leg length discrepancy (e.g., <5mm)

Correct Answer & Explanation

. Persistent component rotational malalignment leading to patellofemoral dysfunction

Explanation

Persistent component rotational malalignment, especially of the femoral component, leading to ongoing patellofemoral dysfunction (e.g., anterior knee pain, maltracking, clunking) is a very challenging problem to correct once established. It often requires complex revision surgery to address. Other issues like mild swelling, incisional pain, transient weakness, or small LLDs are usually self-limiting or easily manageable. Significant rotational malalignment is a major cause of patient dissatisfaction and poor outcomes.

Question 5927

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year-old patient with Stage 3 hallux rigidus presents with moderate pain, but has significant comorbidities including diabetes, peripheral vascular disease, and poor skin integrity. She is unwilling to sacrifice motion completely. Which surgical option carries the highest risk and may be contraindicated in this patient?

. First MTP joint arthrodesis
. Dorsal cheilectomy
. Interpositional arthroplasty with soft tissue
. Silicone implant arthroplasty
. Resection arthroplasty (Keller)

Correct Answer & Explanation

. Silicone implant arthroplasty

Explanation

Silicone implant arthroplasty in the setting of diabetes, peripheral vascular disease, and poor skin integrity carries significant risks, including infection, implant failure, particulate synovitis, osteolysis, and wound healing complications. These comorbidities make any implant surgery challenging and increase the risk of poor outcomes, potentially leading to revision surgery or amputation. While arthrodesis and cheilectomy also have risks, the presence of a foreign body (silicone) significantly amplifies the complication profile in such a high-risk patient. Interpositional arthroplasty with autologous tissue or a resection arthroplasty, while less ideal for motion, might be considered in carefully selected high-risk patients if joint preservation is paramount and arthrodesis is unacceptable, as they avoid foreign material.

Question 5928

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient is undergoing revision surgery for a failed silicone MTP joint implant due to osteolysis and chronic inflammation. What is the most common salvage procedure recommended in such a scenario?

. Repeat silicone implant arthroplasty
. First MTP joint arthrodesis
. Keller arthroplasty with soft tissue interposition
. Proximal phalangeal osteotomy (Moberg)
. Resection of the metatarsal head

Correct Answer & Explanation

. First MTP joint arthrodesis

Explanation

Failure of silicone MTP joint implants due to particulate synovitis, osteolysis, or infection often necessitates revision. In these cases, first MTP joint arthrodesis is the most common and reliable salvage procedure. It provides a stable, pain-free outcome, especially when significant bone loss and inflammation have occurred, which would preclude another implant or an interpositional arthroplasty without structural support. Repeating the implant is contraindicated due to the cause of failure. Keller arthroplasty might be an option if arthrodesis is not tolerated, but fusion is typically preferred for stability and pain relief.

Question 5929

Topic: 3. Adult Reconstruction (Hip & Knee)

What is the main advantage of an autologous interpositional arthroplasty (e.g., using extensor hallucis brevis tendon, joint capsule) over an implant arthroplasty for hallux rigidus?

. Provides more predictable long-term motion restoration
. Lower risk of infection and foreign body reaction (e.g., osteolysis, synovitis)
. Allows for immediate full weight-bearing post-operatively
. Easier and quicker surgical technique
. Higher rate of complete pain relief compared to arthrodesis

Correct Answer & Explanation

. Lower risk of infection and foreign body reaction (e.g., osteolysis, synovitis)

Explanation

The main advantage of autologous interpositional arthroplasty is the avoidance of foreign body reactions, such as synovitis or osteolysis, and a lower risk of infection associated with prosthetic implants. While motion restoration can be variable, and the procedure may not be quicker, it leverages the patient's own tissue to create a cushion within the joint, mitigating implant-related complications. It does not allow for immediate full weight-bearing nor does it typically provide more predictable long-term motion or pain relief than arthrodesis.

Question 5930

Topic: 3. Adult Reconstruction (Hip & Knee)

What potential complication unique to implant arthroplasty (e.g., silicone or metal) for hallux rigidus involves an immune response to particulate debris?

. Hardware prominence
. Nonunion
. Transfer metatarsalgia
. Synovitis and osteolysis
. Superficial wound dehiscence

Correct Answer & Explanation

. Synovitis and osteolysis

Explanation

Synovitis and osteolysis (bone resorption) due to a foreign body reaction to particulate debris are unique and significant complications of implant arthroplasty, particularly with silicone implants. Over time, wear particles from the implant can trigger an inflammatory response within the joint capsule, leading to synovitis and progressive bone loss around the implant, which can result in implant failure and necessitate revision surgery. Hardware prominence, nonunion (not applicable to arthroplasty), transfer metatarsalgia, and wound dehiscence are general surgical complications or issues, but not specific to particulate debris.

Question 5931

Topic: Total Hip Arthroplasty (THA)

The concept of 'stress shielding' in orthopedics primarily refers to:

. Protection of bone from excessive loads by a stiff implant, leading to increased bone density.
. Transfer of stress from bone to a stiffer implant, leading to bone resorption and decreased density.
. The ability of an implant to withstand high stresses without failure.
. A technique to reduce stress on an osteoporotic bone.
. The mechanical stress applied to an implant at its interface with bone.

Correct Answer & Explanation

. Transfer of stress from bone to a stiffer implant, leading to bone resorption and decreased density.

Explanation

Stress shielding occurs when a rigid implant (e.g., a stiff plate or femoral stem) carries a disproportionately high amount of the load, thereby shielding the adjacent bone from its normal physiological stresses. According to Wolff's Law, bone adapts to the loads it experiences. When shielded from stress, the bone undergoes resorption and decreases in density, which can lead to implant loosening or periprosthetic fracture. It is a detrimental phenomenon, not a protective one leading to increased density.

Question 5932

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old obese male with severe tricompartmental osteoarthritis undergoes a total knee arthroplasty. Postoperatively, he develops a warm, red, painful knee with purulent discharge from the wound. CRP and ESR are significantly elevated. What is the most appropriate initial management for this suspected acute periprosthetic joint infection (PJI)?

. Aspiration of the joint for culture and cell count
. Urgent revision surgery with exchange of components
. Long-term suppressive antibiotics
. Debridement, antibiotics, and implant retention (DAIR)
. Knee arthrodesis

Correct Answer & Explanation

. Aspiration of the joint for culture and cell count

Explanation

For any suspected acute periprosthetic joint infection (PJI), the absolute initial management step is diagnostic aspiration of the joint. This allows for synovial fluid cell count (white blood cell count and neutrophil percentage) and culture, which are essential for confirming the diagnosis, identifying the causative organism, and guiding targeted antibiotic therapy. The subsequent surgical management (e.g., DAIR or two-stage revision) depends on the culture results, chronicity of infection, and host factors, but diagnosis is paramount first.

Question 5933

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old male undergoes revision total hip arthroplasty for aseptic loosening. Intraoperatively, during femoral component extraction, a longitudinal fracture of the distal femur occurs. What is the classification of this intraoperative fracture typically associated with revision hip arthroplasty?

. Vancouver Type A
. Vancouver Type B1
. Vancouver Type B2
. Vancouver Type C
. Paprosky Type IV

Correct Answer & Explanation

. Vancouver Type C

Explanation

The Vancouver classification system is widely used for periprosthetic femoral fractures. A Vancouver Type C fracture is defined as a fracture that occursdistal to the tip of the femoral stem. Type B fractures involve the area around the stem (B1: well-fixed stem, B2: loose stem, B3: loose stem with poor bone stock). Type A fractures are trochanteric. The description clearly states the fracture is distal to the stem tip.

Question 5934

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year-old female with a well-fixed, uncemented femoral stem from a prior total hip arthroplasty sustains a fall and develops a periprosthetic fracture distal to the tip of the stem (Vancouver Type C). The stem is not loose. What is the most appropriate surgical treatment?

. Plate fixation with cerclage wires spanning the fracture
. Revision to a longer, cemented stem
. Revision to a longer, uncemented stem
. Non-operative management in a cast brace
. Excision of the femoral stem and Girdlestone arthroplasty

Correct Answer & Explanation

. Plate fixation with cerclage wires spanning the fracture

Explanation

A Vancouver Type C periprosthetic femoral fracture is defined as a fracture distal to the tip of awell-fixedfemoral stem. The treatment aims to stabilize the fracture without needing to revise the well-functioning prosthesis. This is typically achieved with open reduction and internal fixation using a plate and screws, often supplemented with cerclage wires. The plate spans the fracture, extending well proximal and distal to it. Revision of the stem (options B and C) is not indicated if the stem is well-fixed. Non-operative management is rarely successful for unstable periprosthetic fractures.

Question 5935

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient presents with suspected avascular necrosis (AVN) of the femoral head. Plain radiographs are initially normal. Which imaging modality is most sensitive for early detection of avascular necrosis of the femoral head?

. CT scan
. Bone scan
. MRI
. Ultrasound
. PET scan

Correct Answer & Explanation

. MRI

Explanation

Magnetic Resonance Imaging (MRI) is the most sensitive imaging modality for the early detection of avascular necrosis (AVN) of the femoral head. It can identify characteristic changes (e.g., bone marrow edema, a 'double-line sign' at the reactive interface) even before they are visible on plain radiographs, bone scans, or CT scans. Early diagnosis allows for potentially joint-preserving interventions. Other modalities are either less sensitive or used for later stages or other purposes.

Question 5936

Topic: 3. Adult Reconstruction (Hip & Knee)

A 35-year-old male undergoes a total hip arthroplasty. He is very active and has a long life expectancy. The surgeon wants to minimize wear debris and maximize implant longevity. Which bearing surface combination is generally associated with the lowest wear rates in total hip arthroplasty?

. Metal-on-polyethylene
. Ceramic-on-polyethylene
. Metal-on-metal
. Ceramic-on-ceramic
. Polyethylene-on-polyethylene

Correct Answer & Explanation

. Ceramic-on-ceramic

Explanation

Ceramic-on-ceramic (CoC) bearing surfaces in total hip arthroplasty are generally associated with the lowest wear rates and negligible wear debris generation compared to other common bearing surface combinations. This makes CoC an attractive option for young, active patients with a long life expectancy where minimizing wear and the risk of osteolysis (a common long-term complication of wear debris) is paramount. Metal-on-metal has fallen out of favor due to concerns about metal ion release and pseudotumor formation.

Question 5937

Topic: 3. Adult Reconstruction (Hip & Knee)

A 75-year-old female falls at home and sustains a displaced femoral neck fracture. She undergoes an uncemented hemiarthroplasty. Six weeks post-operatively, while attempting to sit in a low chair, she experiences sudden, severe hip pain and shortening of the limb, with the leg held in internal rotation. What is the most likely diagnosis?

. Periprosthetic infection
. Aseptic loosening of the femoral stem
. Posterior dislocation of the femoral head component
. Fracture of the ipsilateral femur
. Heterotopic ossification

Correct Answer & Explanation

. Posterior dislocation of the femoral head component

Explanation

The clinical presentation of sudden, severe hip pain, limb shortening, and the classic post-dislocation position (internal rotation, adduction, flexion for posterior dislocation; external rotation, abduction, flexion for anterior dislocation) after a total hip or hemiarthroplasty strongly suggests prosthetic dislocation. Posterior dislocation is the most common type after THA, often occurring with combined hip flexion, adduction, and internal rotation. Periprosthetic infection or aseptic loosening usually presents with more insidious onset pain. A periprosthetic fracture would likely show distinct radiographic changes. Heterotopic ossification causes stiffness and pain, not acute mechanical instability.

Question 5938

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old male with a history of osteoarthritis underwent a total knee arthroplasty 5 years ago. He now complains of increasing knee pain, especially with activity. Radiographs show subsidence of the tibial component, lucency greater than 2mm around the cement-bone interface of both components, and signs of polyethylene wear. Inflammatory markers are normal. What is the most likely diagnosis?

. Periprosthetic joint infection
. Aseptic loosening
. Patellofemoral pain syndrome
. Extensor mechanism rupture
. Adhesive capsulitis of the knee

Correct Answer & Explanation

. Aseptic loosening

Explanation

The combination of increasing pain with activity, radiographic evidence of component subsidence, and lucency greater than 2mm around the cement-bone interface in multiple zones of both components, along with polyethylene wear, are classic signs of aseptic loosening of a total knee arthroplasty. Normal inflammatory markers further support an aseptic etiology. Periprosthetic joint infection would typically present with elevated inflammatory markers, though chronic low-grade infections can be subtle. Patellofemoral pain syndrome is specific to the patellofemoral joint. Extensor mechanism rupture is an acute, dramatic event. Adhesive capsulitis is more common in the shoulder and would present with global stiffness.

Question 5939

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following describes the optimal indication for using an uncemented femoral stem in a total hip arthroplasty?

. Elderly patient with severe osteoporosis and poor bone quality
. Patient with active inflammatory arthritis requiring early weight bearing
. Young, active patient with good bone quality
. Revision surgery for aseptic loosening of a cemented stem
. Obese patient requiring immediate full weight bearing

Correct Answer & Explanation

. Young, active patient with good bone quality

Explanation

Uncemented femoral stems rely on biological fixation (bone ingrowth) for long-term stability. Therefore, they are optimally indicated in younger, active patients with good bone quality who have the biological capacity for bone ingrowth into the porous-coated surface of the implant. Elderly patients with severe osteoporosis and poor bone quality often benefit from cemented stems for immediate mechanical interlock and stability. Revision surgery for aseptic loosening often considers uncemented options, but 'optimal indication' refers to primary surgery. Early full weight-bearing might be achieved with a good press-fit, but cemented stems generally allow for more immediate full weight-bearing in certain scenarios due to immediate mechanical stability.

Question 5940

Topic: 3. Adult Reconstruction (Hip & Knee)
Which of the following biomaterials used in total hip arthroplasty (THA) has historically been most associated with osteolysis due to particulate wear debris?
. Cobalt-chromium alloy
. Titanium alloy
. Polyethylene
. Ceramic
. Stainless steel

Correct Answer & Explanation

. Polyethylene

Explanation

Ultra-high molecular weight polyethylene (UHMWPE) has historically been the leading cause of osteolysis in total hip arthroplasty. Wear debris generated from the polyethylene acetabular liner (articulating with a metal or ceramic femoral head) stimulates a macrophage-mediated inflammatory response that leads to bone resorption (osteolysis) and subsequent aseptic loosening. While metal-on-metal implants have also been associated with adverse tissue reactions and osteolysis from metal ion release, polyethylene was the predominant material associated with osteolysis in earlier generations of THA. Ceramic and metal alloys are used for the femoral head and stem, but polyethylene is the primary bearing surface responsible for wear-induced osteolysis.

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