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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 119 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 2361

Topic: 3. Adult Reconstruction (Hip & Knee)

During a total knee arthroplasty in a patient with a severe fixed varus deformity, the medial soft tissues are exceedingly tight in both flexion and extension. After releasing the deep medial collateral ligament (MCL) and removing all medial osteophytes, the joint remains tight medially. What is the next most appropriate sequential step for medial release?

. Release the lateral collateral ligament
. Release the semimembranosus insertion and posteromedial capsule
. Complete release of the superficial MCL off its distal tibial insertion
. Release the popliteus tendon
. Release the medial head of the gastrocnemius

Correct Answer & Explanation

. Release the semimembranosus insertion and posteromedial capsule

Explanation

The standard sequence for soft tissue release in a varus knee includes: 1) Removal of medial osteophytes and deep MCL release, 2) Release of the posteromedial corner (semimembranosus and posteromedial capsule) - especially if the knee is tight in extension, 3) Release of the superficial MCL (subperiosteal peeling off the proximal tibia). Releasing the semimembranosus/posteromedial capsule is typically done prior to a complete release of the superficial MCL to avoid over-releasing and causing gross medial instability.

Question 2362

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following synovial fluid biomarkers is an antimicrobial peptide released primarily by neutrophils and has demonstrated both high sensitivity and high specificity for diagnosing periprosthetic joint infection (PJI)?

. C-reactive protein (CRP)
. Interleukin-6 (IL-6)
. Alpha-defensin
. Leukocyte esterase
. Procalcitonin

Correct Answer & Explanation

. Alpha-defensin

Explanation

Alpha-defensin is a biomarker released by host neutrophils in response to pathogens. It is highly accurate for diagnosing periprosthetic joint infection (PJI). Studies have shown it maintains high sensitivity and specificity even in scenarios where other inflammatory markers may be equivocal (such as concurrent systemic inflammatory diseases or prior antibiotic administration).

Question 2363

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old male with a metal-on-metal total hip arthroplasty placed 10 years ago presents with persistent groin pain. MRI reveals a large, solid-cystic mass communicating with the joint. Biopsy of the periprosthetic tissue is most likely to demonstrate which of the following histopathological hallmarks characteristic of Aseptic Lymphocytic Vasculitis-Associated Lesions (ALVAL)?

. Abundant multinucleated foreign body giant cells containing polyethylene particles
. Acute neutrophilic exudate extending to the bone-cement interface
. Extensive spindle cell proliferation with high mitotic activity
. Sheet-like infiltration of foamy macrophages with cholesterol clefts
. Extensive perivascular lymphocytic infiltrates

Correct Answer & Explanation

. Extensive perivascular lymphocytic infiltrates

Explanation

ALVAL (Aseptic Lymphocytic Vasculitis-Associated Lesions) is an adverse local tissue reaction (ALTR) specifically associated with metal-on-metal implants or mechanically assisted crevice corrosion (trunnionosis). Histologically, it is a delayed-type (Type IV) hypersensitivity reaction characterized by an extensive perivascular infiltrate of lymphocytes (mostly T-cells), macrophages, and tissue necrosis. Polyethylene wear causes a different reaction dominated by macrophages and foreign body giant cells.

Question 2364

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary posterior-stabilized (PS) total knee arthroplasty, using a measured resection technique, the surgeon evaluates the gaps. The knee is perfectly balanced and symmetrical in extension, but it is too tight in flexion bilaterally. Which of the following is the most appropriate step to balance the knee?

. Resect more distal femur
. Release the posterior capsule
. Downsize the femoral component and use anterior referencing
. Upsize the femoral component
. Insert a thinner tibial polyethylene liner

Correct Answer & Explanation

. Downsize the femoral component and use anterior referencing

Explanation

When the knee is tight in flexion but balanced in extension, the flexion gap needs to be increased without affecting the extension gap. Downsizing the femoral component (using anterior referencing to take more bone off the posterior condyles) will increase the flexion gap without altering the extension space. Resecting more distal femur only increases the extension gap. A thinner liner would make the extension gap loose.

Question 2365

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old female underwent a total hip arthroplasty (THA) utilizing a ceramic-on-ceramic bearing surface one year ago. She now complains of a loud, audible squeaking sound originating from her hip during normal ambulation. Which of the following factors regarding component positioning is most strongly associated with this complication?

. Acetabular cup retroversion
. Edge loading due to a steeply placed acetabular cup
. Excessive femoral stem varus
. Excessive femoral anteversion
. Impingement of the greater trochanter on the ilium

Correct Answer & Explanation

. Edge loading due to a steeply placed acetabular cup

Explanation

Squeaking is a known complication specific to hard-on-hard bearing surfaces, most notably ceramic-on-ceramic THA. The primary etiology is edge loading, which disrupts the fluid film lubrication. Edge loading is most frequently caused by acetabular cup malposition, specifically excessive abduction (a 'steep' cup) or version errors, as well as impingement leading to micro-separation.

Question 2366

Topic: 3. Adult Reconstruction (Hip & Knee)



During a posterior-stabilized Total Knee Arthroplasty (TKA), the surgeon utilizes spacer blocks and finds that the knee is perfectly balanced in full extension, but tight in 90 degrees of flexion. What is the most appropriate surgical modification to correct this specific imbalance?

. Release the posterior capsule
. Resect more bone from the distal femur
. Upsize the femoral component and use a thinner polyethylene insert
. Downsize the femoral component and cut more posterior condyle
. Release the medial collateral ligament

Correct Answer & Explanation

. Downsize the femoral component and cut more posterior condyle

Explanation

When a TKA is balanced in extension but tight in flexion, the flexion gap must be increased without altering the extension gap. This is achieved by either downsizing the femoral component (which removes more posterior condylar bone, opening the flexion gap) or increasing the posterior slope of the tibial cut (which also increases the flexion gap relatively more than the extension gap). Releasing the posterior capsule or resecting more distal femur would affect the extension gap.

Question 2367

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old male presents with a new-onset squeaking noise 3 years after a total hip arthroplasty. He is otherwise asymptomatic and radiographs show well-fixed components.

What is the most likely biomechanical etiology of this phenomenon?

. Impingement of the neck on the rim causing edge loading
. Asymptomatic loosening of the femoral stem
. Corrosion at the head-neck junction (trunnionosis)
. Subclinical periprosthetic joint infection
. Catastrophic failure of a polyethylene liner

Correct Answer & Explanation

. Impingement of the neck on the rim causing edge loading

Explanation

Ceramic-on-ceramic (CoC) bearing surfaces in total hip arthroplasty are known to occasionally produce a squeaking sound. The most common cause of squeaking in CoC articulations is edge loading, which often results from component malposition (e.g., steep cup inclination or excessive anteversion) leading to micro-separation, stripe wear, and loss of fluid film lubrication.

Question 2368

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old female presents with a painful 'catch' and a palpable, audible pop in her knee when extending from 40 degrees of flexion to full extension. She is 1 year status-post a posterior-stabilized total knee arthroplasty.

If non-operative management fails, what is the most appropriate surgical treatment?

. Revision of the femoral component to a cruciate-retaining design
. Arthroscopic excision of a fibrous nodule
. Isolated patellar resurfacing
. Lateral retinacular release
. Tibial tubercle osteotomy for patellar tracking

Correct Answer & Explanation

. Arthroscopic excision of a fibrous nodule

Explanation

The patient's symptoms are classic for patellar clunk syndrome, a complication specific to posterior-stabilized (PS) total knee arthroplasty designs. It occurs when a fibrosynovial nodule develops on the deep surface of the distal quadriceps tendon and catches in the intercondylar box of the femoral component during extension. The treatment of choice after failed conservative management is arthroscopic or open excision of the nodule.

Question 2369

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following is a major criterion for the diagnosis of Periprosthetic Joint Infection (PJI) according to the 2018 International Consensus Meeting (ICM)?

. Purulence in the affected joint
. Elevated synovial C-reactive protein (CRP)
. A single positive culture of a highly virulent organism
. Two positive periprosthetic cultures with phenotypically identical organisms
. Elevated synovial leukocyte esterase

Correct Answer & Explanation

. Two positive periprosthetic cultures with phenotypically identical organisms

Explanation

According to the 2018 ICM criteria for PJI, there are two major criteria: 1) Two positive periprosthetic cultures with phenotypically identical organisms, and 2) A sinus tract communicating with the joint. The presence of either major criterion is diagnostic for PJI. The other options represent minor criteria or findings that contribute to the aggregate score but are not major criteria on their own.

Question 2370

Topic: 3. Adult Reconstruction (Hip & Knee)

During a total hip arthroplasty, the surgeon decides to use a high-offset femoral stem, which effectively lateralizes the greater trochanter. What is the expected biomechanical effect of this modification?

. Decrease the abductor moment arm and increase joint reaction force
. Increase the abductor moment arm and decrease joint reaction force
. Decrease the abductor moment arm and decrease joint reaction force
. Increase the abductor moment arm and increase joint reaction force
. Increase the center of rotation and decrease the bending moment on the stem

Correct Answer & Explanation

. Increase the abductor moment arm and decrease joint reaction force

Explanation

Increasing the femoral offset lateralizes the greater trochanter and the insertion of the hip abductors. This increases the abductor moment arm (lever arm). As a result, less force is required from the abductor muscles to maintain a level pelvis during single-leg stance, which in turn decreases the overall joint reaction force across the hip joint.

Question 2371

Topic: 3. Adult Reconstruction (Hip & Knee)

In a posterior-stabilized (PS) total knee arthroplasty, the cam-and-post mechanism is designed primarily to replicate the function of which native knee structure to facilitate femoral rollback during flexion?

. Anterior cruciate ligament
. Posterior cruciate ligament
. Medial collateral ligament
. Lateral collateral ligament
. Popliteus tendon

Correct Answer & Explanation

. Posterior cruciate ligament

Explanation

The cam and post mechanism in a PS TKA engages during deep flexion to substitute for the resected Posterior Cruciate Ligament (PCL). This forces the femur to translate posteriorly on the tibia (femoral rollback), improving maximal flexion and preventing anterior subluxation of the femur.

Question 2372

Topic: 3. Adult Reconstruction (Hip & Knee)
A 65-year-old male presents with new-onset groin pain and a palpable mass 6 years following a primary Metal-on-Polyethylene (MoP) total hip arthroplasty (THA). A MARS MRI demonstrates a solid and cystic soft-tissue mass. Laboratory testing reveals elevated serum Cobalt levels (>10 ppb) with relatively normal Chromium levels. Infection is ruled out. What is the most likely underlying mechanism for his presentation?
. Adverse local tissue reaction due to bearing surface wear
. Mechanically assisted crevice corrosion at the head-neck taper
. Polyethylene-induced osteolysis
. Aseptic loosening of the femoral stem
. Ceramic liner fracture

Correct Answer & Explanation

. Mechanically assisted crevice corrosion at the head-neck taper

Explanation

The clinical scenario describes trunnionosis, or mechanically assisted crevice corrosion (MACC), occurring at the modular head-neck junction (trunnion) of the femoral stem. In a Metal-on-Polyethylene (MoP) THA, elevated cobalt levels in the presence of normal chromium levels strongly suggest corrosion at a modular junction (typically a CoCr head on a titanium stem), not bearing surface wear. This process can lead to an adverse local tissue reaction (ALTR/ALVAL) and pseudotumor formation.

Question 2373

Topic: 3. Adult Reconstruction (Hip & Knee)

During a cruciate-retaining (CR) total knee arthroplasty (TKA), the surgeon evaluates the kinematics of the implant after trial components are placed. If the posterior cruciate ligament (PCL) is excessively tight, which of the following kinematic abnormalities is most likely to be observed?

. Excessive femoral rollback causing tightness in deep flexion and anterior tibial lift-off
. Anterior translation of the femur on the tibia during deep flexion
. A symmetric extension gap but a highly asymmetric flexion gap
. Hyperextension of the knee joint with posterior sag
. Patellar clunk syndrome during terminal extension

Correct Answer & Explanation

. Excessive femoral rollback causing tightness in deep flexion and anterior tibial lift-off

Explanation

In a CR TKA, an intact and appropriately balanced PCL acts to induce femoral rollback during knee flexion. If the PCL is excessively tight, it will pull the femur posteriorly too early and forcefully during flexion, leading to excessive femoral rollback. This effectively decreases the flexion gap (making it tight in deep flexion) and can cause the anterior aspect of the tibial tray to lift off. It does not cause anterior femoral translation (which would happen if the PCL were deficient).

Question 2374

Topic: 3. Adult Reconstruction (Hip & Knee)

A surgeon performs a primary posterior-stabilized total knee arthroplasty (TKA). During trialing, the knee is perfectly balanced in full extension, but the trial components are overly tight in flexion, limiting motion to 85 degrees. The joint line is appropriately restored. What is the most appropriate next step to correct this specific imbalance?

. Resect more distal femur
. Decrease the anterior-posterior size of the femoral component
. Release the posterior capsule
. Recut the proximal tibia to increase resection thickness
. Increase the anterior-posterior size of the femoral component

Correct Answer & Explanation

. Decrease the anterior-posterior size of the femoral component

Explanation

A knee that is balanced in extension but tight in flexion indicates an isolated flexion gap issue. The most appropriate way to increase the flexion gap without affecting the extension gap is to decrease the anterior-posterior size of the femoral component, which decreases the posterior condylar offset. Resecting more distal femur or recutting the proximal tibia would inappropriately widen the extension gap.

Question 2375

Topic: Total Hip Arthroplasty (THA)

A 72-year-old female is undergoing a primary total hip arthroplasty via a posterior approach. During trial reduction, the hip is found to be highly unstable, dislocating posteriorly when the leg is placed in flexion, adduction, and internal rotation. The surgeon determines the acetabular and femoral components are oriented in perfect native version and inclination, but there is significant soft tissue laxity. The femoral head trial is currently a standard neck (+0). Which of the following component adjustments would most appropriately address this instability?

. Increase the femoral head length (e.g., to +4 or +8)
. Decrease the femoral head length (e.g., to -4)
. Decrease acetabular anteversion
. Decrease femoral anteversion
. Use an elevated rim liner positioned posteroinferiorly

Correct Answer & Explanation

. Increase the femoral head length (e.g., to +4 or +8)

Explanation

In the setting of a posterior approach THA with posterior instability due to soft-tissue laxity (and correctly positioned components), increasing the femoral offset and leg length by using a longer offset head (e.g., +4 or +8) increases myofascial tissue tension, particularly of the abductors and external rotators, thereby stabilizing the hip joint. Decreasing anteversion or head length would worsen posterior instability.

Question 2376

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old highly active male is undergoing a total hip arthroplasty (THA). The surgeon is discussing bearing surface options with him. Which of the following is a recognized biomechanical or clinical characteristic of ceramic-on-ceramic (CoC) bearings compared to metal-on-polyethylene (MoP) bearings?

. Higher linear and volumetric wear rates
. Elimination of squeaking risk postoperatively
. Reduced risk of volumetric wear and subsequent osteolysis
. Increased susceptibility to third-body wear damage
. Increased systemic metal ion levels requiring annual monitoring

Correct Answer & Explanation

. Reduced risk of volumetric wear and subsequent osteolysis

Explanation

Ceramic-on-ceramic (CoC) bearings possess excellent scratch resistance and have the lowest linear and volumetric wear rates among the available bearing surfaces, significantly reducing the incidence of wear particle-induced osteolysis. However, they carry a unique risk of squeaking and catastrophic ceramic component fracture.

Question 2377

Topic: 3. Adult Reconstruction (Hip & Knee)



A 75-year-old female sustains a displaced femoral neck fracture. Prior to the injury, she was highly active, living independently, and ambulating without assistive devices. She undergoes a total hip arthroplasty (THA). Compared to a bipolar hemiarthroplasty, what is a known long-term clinical advantage of THA for this specific patient profile?

. Significantly lower dislocation rate
. Lower intraoperative surgical blood loss
. Shorter mean operative time
. Lower risk of long-term reoperation for any reason
. Reduced postoperative risk of deep vein thrombosis

Correct Answer & Explanation

. Lower risk of long-term reoperation for any reason

Explanation

In active, independent older adults with displaced femoral neck fractures, total hip arthroplasty (THA) is associated with better functional outcomes, less long-term groin pain (no acetabular cartilage wear), and lower long-term reoperation rates compared to hemiarthroplasty. This comes at the expense of a higher initial risk of dislocation, longer surgical times, and increased blood loss.

Question 2378

Topic: 3. Adult Reconstruction (Hip & Knee)



During a primary posterior-stabilized (PS) total knee arthroplasty, the surgeon notices that the knee has symmetric extension and flexion gaps at 90 degrees, but exhibits a sudden 'cam jump' phenomenon when the knee is passively flexed past 110 degrees. Which of the following intraoperative variables is the most likely cause of this kinematic abnormality?

. A pathologically loose flexion gap relative to the size of the components
. An excessively tight extension gap due to inadequate distal femoral resection
. Use of an oversized femoral component causing patellofemoral overstuffing
. The tibial component being placed with excessive anterior slope
. Significant joint line elevation from extensive distal femoral cuts

Correct Answer & Explanation

. A pathologically loose flexion gap relative to the size of the components

Explanation

In a posterior-stabilized (PS) TKA, 'cam jump' or dislocation of the cam-post mechanism typically occurs in deep flexion. The primary cause of this phenomenon is a loose flexion gap (often combined with insufficient posterior tibial slope or a small femoral component). This laxity allows the femur to translate anteriorly relative to the tibia in deep flexion, clearing the post.

Question 2379

Topic: 3. Adult Reconstruction (Hip & Knee)

During a posterior-stabilized total knee arthroplasty utilizing an anterior referencing guide, the surgeon notes that the knee is tight in flexion and well-balanced in extension. Which of the following is the most appropriate intraoperative step to balance the knee?

. Recut the distal femur to remove more bone
. Decrease the size of the femoral component
. Decrease the posterior slope of the tibial cut
. Recut the proximal tibia to remove more bone
. Release the posterior cruciate ligament

Correct Answer & Explanation

. Decrease the size of the femoral component

Explanation

A knee that is tight in flexion but balanced in extension requires a maneuver that exclusively increases the flexion gap. When using an anterior referencing system, decreasing the femoral component size selectively decreases the posterior condylar offset (thinner posterior cut), which enlarges the flexion space without altering the extension space.

Question 2380

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary posterior-stabilized total knee arthroplasty, the surgeon assesses the flexion and extension gaps. The knee is found to be tight in both extension and flexion. Which of the following surgical adjustments is the most appropriate next step?

. Resect more distal femur
. Resect more proximal tibia
. Upsize the femoral component
. Downsize the femoral component
. Release the posterior cruciate ligament

Correct Answer & Explanation

. Resect more proximal tibia

Explanation

In gap balancing for total knee arthroplasty, the proximal tibial cut affects both the flexion and extension gaps equally. If the knee is symmetrically tight in both flexion and extension, resecting more proximal tibia (or using a thinner tibial polyethylene insert) will increase both gaps equally. Resecting more distal femur would only loosen the extension gap. Changing the femoral size primarily affects the flexion gap (downsizing loosens flexion; upsizing tightens flexion).

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