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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 240 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 4781

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient with a history of an arthrodesed (fused) hip from a childhood infection now presents with severe low back pain and ipsilateral knee pain. He requests a takedown of the hip fusion and conversion to a Total Hip Arthroplasty. He must be heavily counseled about the high rate of complications. What is the most likely neuromuscular complication following this specific procedure?

. Femoral nerve palsy
. Postoperative dislocation and permanent Trendelenburg gait due to profound abductor insufficiency
. Foot drop due to common peroneal nerve transection
. Reflex sympathetic dystrophy
. Heterotopic ossification locking the joint completely

Correct Answer & Explanation

. Femoral nerve palsy

Explanation

Because the hip has been fused for decades, the gluteal (abductor) muscles are severely atrophied and fibrotic. Even if the bony takedown is successful, patients universally suffer from severe, irreversible abductor weakness, leading to a permanent Trendelenburg lurch and a very high risk of recurrent dislocation.

Question 4782

Topic: 3. Adult Reconstruction (Hip & Knee)

A 75-year-old male with gouty arthritis of the knee undergoes an aspiration of an acutely swollen joint. What is the classic finding under polarized light microscopy for this condition?

. Positively birefringent rhomboid crystals
. Gram-positive cocci in clusters
. Cholesterol crystals
. Negatively birefringent needle-shaped crystals
. Avascular necrosis fragments

Correct Answer & Explanation

. Positively birefringent rhomboid crystals

Explanation

Gout is caused by the precipitation of monosodium urate crystals in the joint. Under polarized light microscopy, these classically appear as negatively birefringent, needle-shaped crystals (appearing yellow when parallel to the compensator axis). Pseudogout (CPPD) features positively birefringent rhomboid crystals.

Question 4783

Topic: 3. Adult Reconstruction (Hip & Knee)

A 60-year-old diabetic patient with neuropathy presents with a massively swollen, painless knee. Radiographs reveal severe osseous destruction, debris, dislocation, and dense sclerosis. You diagnose Charcot arthropathy. If conservative bracing fails, what is the required component constraint if performing a Total Knee Arthroplasty?

. Cruciate-retaining (CR) knee
. Rotating hinge or highly constrained knee (CCK)
. Unicompartmental knee arthroplasty
. Standard Posterior-Stabilized (PS) knee
. Bi-cruciate retaining knee

Correct Answer & Explanation

. Cruciate-retaining (CR) knee

Explanation

Charcot arthropathy (neuropathic joint) is marked by profound ligamentous laxity and sensory loss. Standard unconstrained implants (CR or PS) will inevitably fail due to instability and massive bone loss. High constraint, typically a rotating hinge knee with long cemented stems, is required to prevent catastrophic dislocation.

Question 4784

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient presents with thigh pain 10 years after receiving a cementless THA. Radiographs show a well-fixed stem but extensive expansile osteolysis in Gruen zones 1 and 7, localized around the metaphysis. The liner is severely worn. What is the most appropriate surgical treatment?

. Component retention, isolated polyethylene liner exchange, and bone grafting of the osteolytic lesions
. Complete extraction of the well-fixed stem and revision to a long fluted stem
. Two-stage revision with an antibiotic spacer
. Cortical strut allograft only
. Amputation

Correct Answer & Explanation

. Component retention, isolated polyethylene liner exchange, and bone grafting of the osteolytic lesions

Explanation

In the presence of massive osteolysis but awell-fixedcementless component, the morbidity of extracting the stem is high and unnecessary. The gold standard is to retain the stable stem, perform a polyethylene liner exchange (to stop the particulate generator), and pack the osteolytic cysts with bone graft.

Question 4785

Topic: Total Hip Arthroplasty (THA)

A 65-year-old male with end-stage hip osteoarthritis is being templated for a THA. It is critical to restore the femoral offset. If the surgeon selects a femoral stem with a high offset option (standard vs high offset neck), what is the primary biomechanical effect on the hip joint?

. It increases the lever arm of the abductor mechanism, decreasing the joint reaction force
. It increases the leg length by exactly the amount of offset added
. It decreases the tension on the abductor muscles, increasing the risk of dislocation
. It shifts the center of rotation medially
. It directly decreases the risk of sciatic nerve stretch

Correct Answer & Explanation

. It increases the lever arm of the abductor mechanism, decreasing the joint reaction force

Explanation

Increasing femoral offset (the horizontal distance from the center of the femoral head to the anatomical axis of the femur) increases the moment arm of the abductor muscles. This allows the abductors to stabilize the pelvis with less force, which consequently decreases the overall joint reaction force pressing into the acetabulum, reducing wear.

Question 4786

Topic: Total Hip Arthroplasty (THA)

A 55-year-old female presents with bilateral osteoarthritis of the hip secondary to developmental dysplasia. She undergoes a THA. The acetabular cup is placed in the "safe zone" defined by Lewinnek. What are the specific angular parameters of the Lewinnek safe zone?

. 10° ± 5° inclination and 5° ± 5° anteversion
. 50° ± 10° inclination and 30° ± 10° anteversion
. 40° ± 10° inclination and 15° ± 10° anteversion
. 30° ± 5° inclination and 0° anteversion
. 45° ± 10° inclination and 45° ± 10° anteversion

Correct Answer & Explanation

. 10° ± 5° inclination and 5° ± 5° anteversion

Explanation

The historical Lewinnek "safe zone" for acetabular component placement to minimize dislocation risk is 40° ± 10° of inclination (abduction) and 15° ± 10° of anteversion.

Question 4787

Topic: 3. Adult Reconstruction (Hip & Knee)

During routine primary TKA, the surgeon utilizes an anterior referencing system to size the femur. The surgeon selects a size that requires a large amount of anterior bone resection. If the anterior femoral cut notches the anterior cortex of the femur, what catastrophic complication is the patient at high risk for?

. Aseptic loosening of the femoral component
. Patellar clunk syndrome
. Patellar tendon rupture
. Periprosthetic supracondylar femur fracture
. Popliteal artery pseudoaneurysm

Correct Answer & Explanation

. Aseptic loosening of the femoral component

Explanation

Notching the anterior femoral cortex creates a massive stress riser in the supracondylar region of the femur. This significantly weakens the bone under torsional and bending loads, leading to a high incidence of postoperative periprosthetic femur fractures.

Question 4788

Topic: 3. Adult Reconstruction (Hip & Knee)
A 30-year-old male with sickle cell disease develops bilateral osteonecrosis (avascular necrosis) of the femoral heads. He has Ficat Stage III disease (subchondral collapse with crescent sign) and severe pain. Core decompression has failed. What is the most appropriate definitive surgical management?
. Total Hip Arthroplasty (THA)
. Free vascularized fibular graft
. Hemiarthroplasty
. Repeat core decompression
. Proximal femoral osteotomy

Correct Answer & Explanation

. Total Hip Arthroplasty (THA)

Explanation

Once the femoral head has collapsed (Ficat Stage III or IV), joint-preserving procedures like core decompression or vascularized grafting have a very high failure rate. Total Hip Arthroplasty (THA) is the treatment of choice to restore function and relieve pain, despite the younger age and medical complexities.

Question 4789

Topic: 3. Adult Reconstruction (Hip & Knee)

In patients undergoing TKA, leaving the patella unresurfaced may be chosen by some surgeons. What is the most common complication and reason for reoperation in patients who receive a TKA without patellar resurfacing?

. Anterior knee pain (patellofemoral pain)
. Patellar tendon rupture
. Patellar fracture
. Aseptic loosening of the tibial component
. Infection

Correct Answer & Explanation

. Anterior knee pain (patellofemoral pain)

Explanation

The most common complication of not resurfacing the patella during TKA is persistent anterior knee pain. This is also the leading cause for secondary reoperation (to retroactively resurface the patella). Resurfacing generally carries a slightly higher risk of patellar fracture, but lowers the risk of anterior knee pain.

Question 4790

Topic: Total Knee Arthroplasty (TKA)

A 60-year-old male with a history of a high tibial osteotomy (HTO) 10 years ago now requires a TKA for end-stage arthritis. A classic anatomic complication of a previous closing-wedge HTO is "patella baja". What surgical difficulty does patella baja present during the TKA?

. Increased risk of popliteal artery injury
. Difficulty everting the patella and exposing the joint
. Excessive laxity of the LCL
. Inability to achieve full extension postoperatively
. Higher rate of metal allergy

Correct Answer & Explanation

. Increased risk of popliteal artery injury

Explanation

Patella baja (an abnormally low-riding patella) occurs after HTO due to contracture/scarring of the patellar tendon. During TKA, this shortened tendon makes it extremely difficult to evert the patella and expose the joint, significantly increasing the risk of avulsing the patellar tendon from the tibial tubercle.

Question 4791

Topic: 3. Adult Reconstruction (Hip & Knee)

Intraoperatively during a primary total knee arthroplasty (TKA), the surgeon notes the joint is excessively tight in flexion but symmetric and well-balanced in extension. Which of the following is the most appropriate next step to achieve a balanced gap?

. Recut the proximal tibia to remove more bone
. Upsize the femoral component
. Downsize the femoral component using an anterior referencing guide
. Downsize the femoral component using a posterior referencing guide
. Release the posterior cruciate ligament (PCL)

Correct Answer & Explanation

. Recut the proximal tibia to remove more bone

Explanation

A tight flexion gap with a balanced extension gap requires decreasing the anteroposterior (AP) diameter of the femur. Downsizing the femoral component with an anterior referencing guide removes more posterior condylar bone, selectively increasing the flexion gap.

Question 4792

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old male presents with a painful TKA 2 years postoperatively. Aspiration yields a synovial fluid WBC count of 4,500 cells/µL with 85% polymorphonuclear leukocytes (PMNs). Serum CRP is 15 mg/L. According to MSIS criteria, what is the most appropriate next step in management?

. Perform a one-stage revision arthroplasty
. Proceed to a two-stage exchange arthroplasty
. Prescribe 6 weeks of intravenous antibiotics
. Perform an urgent diagnostic arthroscopy
. Obtain an alpha-defensin test to confirm the diagnosis

Correct Answer & Explanation

. Perform a one-stage revision arthroplasty

Explanation

According to MSIS criteria, chronic periprosthetic joint infection (PJI) is diagnosed with a synovial WBC >3000 cells/µL and PMNs >80%. The gold standard of care for a chronic PJI in North America is a two-stage exchange arthroplasty.

Question 4793

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old active female with a ceramic-on-ceramic total hip arthroplasty (THA) complains of a squeaking noise from her hip when walking or bending. Radiographs show a well-fixed stem and cup. What is the most likely biomechanical cause of this phenomenon?

. Stripe wear from edge loading due to cup malposition
. Trunnionosis at the head-neck junction
. Polyethylene wear debris accumulation
. Impingement of the iliopsoas tendon
. Femoral stem subsidence

Correct Answer & Explanation

. Stripe wear from edge loading due to cup malposition

Explanation

Squeaking in ceramic-on-ceramic THA is highly associated with edge loading, often secondary to component malposition (e.g., steep cup inclination or excessive anteversion). This disrupts fluid film lubrication and leads to stripe wear.

Question 4794

Topic: 3. Adult Reconstruction (Hip & Knee)

A 78-year-old female sustains a fall and presents with thigh pain. Radiographs reveal a periprosthetic fracture around the stem of her THA. The fracture extends just below the tip of the stem. The stem is visibly loose, but the proximal femoral bone stock is adequate. What is the most appropriate treatment?

. Open reduction internal fixation with cables and locking plates
. Revision to a long cementless diaphyseal-engaging stem
. Revision to a fully porous-coated cylindrical stem with impaction bone grafting
. Non-operative management with a functional brace
. Proximal femoral replacement

Correct Answer & Explanation

. Open reduction internal fixation with cables and locking plates

Explanation

This describes a Vancouver B2 periprosthetic fracture (fracture around the stem, loose implant, good bone stock). The standard treatment involves revision arthroplasty using a long uncemented diaphyseal-fitting stem to bypass the fracture.

Question 4795

Topic: Total Knee Arthroplasty (TKA)

A 72-year-old man undergoes revision TKA. Six months later, he presents with an inability to actively extend his knee and a palpable gap at the patellar tendon. Which reconstruction method provides the most reliable long-term clinical outcome for this chronic disruption?

. Primary end-to-end repair with heavy nonabsorbable suture
. Semitendinosus autograft augmentation
. Achilles tendon allograft with a calcaneal bone block
. Synthetic mesh augmentation (e.g., Marlex mesh)
. Gastrocnemius rotational flap

Correct Answer & Explanation

. Primary end-to-end repair with heavy nonabsorbable suture

Explanation

Recent literature demonstrates that synthetic mesh (e.g., Marlex) reconstruction for chronic extensor mechanism disruption offers lower failure rates and better functional outcomes compared to traditional allograft reconstructions.

Question 4796

Topic: 3. Adult Reconstruction (Hip & Knee)

A 62-year-old male with a metal-on-metal hip resurfacing complains of groin pain and swelling 5 years postoperatively. Joint aspiration is negative for infection. MRI with MARS reveals a large cystic mass communicating with the joint. What histological finding is most expected?

. Abundant polymorphonuclear leukocytes
. Aseptic lymphocytic vasculitis-associated lesion (ALVAL)
. Massive sheets of foamy macrophages with birefringent particles
. Palisading granulomas with central caseating necrosis
. Woven bone formation with active osteoblasts

Correct Answer & Explanation

. Abundant polymorphonuclear leukocytes

Explanation

Metal-on-metal adverse local tissue reactions (pseudotumors) are histologically characterized by an ALVAL response. This involves a delayed Type IV hypersensitivity reaction with dense perivascular lymphocytic infiltration.

Question 4797

Topic: Total Knee Arthroplasty (TKA)

Following a primary TKA, the surgeon observes lateral patellar tracking during the trial range of motion. Which of the following technical errors most commonly causes this issue?

. Internal rotation of the femoral component
. External rotation of the tibial component
. External rotation of the femoral component
. Lateralization of the femoral component
. Medialization of the patellar button

Correct Answer & Explanation

. Internal rotation of the femoral component

Explanation

Internal rotation of the tibial and/or femoral components effectively increases the Q-angle, leading to lateral patellar maltracking. External rotation of these components improves tracking.

Question 4798

Topic: Total Knee Arthroplasty (TKA)

A 68-year-old female presents with a painful catching sensation at 30 degrees of flexion when actively extending her knee. She underwent a posterior-stabilized TKA 1 year ago. What is the most appropriate definitive management?

. Revision of the femoral component
. Revision of the patellar button
. Arthroscopic excision of a fibrotic nodule
. Open synovectomy and spacer exchange
. Physiotherapy focusing on VMO strengthening

Correct Answer & Explanation

. Revision of the femoral component

Explanation

Patellar clunk syndrome occurs in posterior-stabilized TKA designs due to a fibrotic nodule forming at the superior pole of the patella that catches in the intercondylar notch. The definitive treatment is arthroscopic or open excision of the nodule.

Question 4799

Topic: Total Hip Arthroplasty (THA)

A surgeon is performing a direct anterior approach for a THA. Postoperatively, the patient notes numbness and a burning sensation over the anterolateral aspect of the operative thigh. Which surgical maneuver most likely caused this complication?

. Aggressive medial retraction of the sartorius muscle
. Aggressive lateral retraction of the tensor fasciae latae
. Placement of an anterior retractor over the pelvic brim
. Releasing the short external rotators
. Reaming the acetabulum too deeply

Correct Answer & Explanation

. Aggressive medial retraction of the sartorius muscle

Explanation

The lateral femoral cutaneous nerve (LFCN) is at risk during the direct anterior approach to the hip. Aggressive medial retraction of the sartorius or rectus femoris can stretch or directly injure the LFCN.

Question 4800

Topic: Total Knee Arthroplasty (TKA)

During a complex revision TKA, the surgeon encounters complete avulsion and absence of the medial collateral ligament (MCL). The lateral collateral ligament is intact. Which level of implant constraint is strictly required?

. Cruciate Retaining (CR)
. Posterior Stabilized (PS)
. Constrained Condylar Knee (CCK)
. Rotating Hinge
. Fixed Bearing Unicompartmental

Correct Answer & Explanation

. Cruciate Retaining (CR)

Explanation

Complete disruption or absence of the MCL generally requires a rotating hinge prosthesis to provide adequate stability. A CCK implant relies on at least one partially functioning collateral ligament to prevent catastrophic failure of the central post.

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