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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 263 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 5241

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old female presents with thigh pain following a fall. Radiographs demonstrate a transverse fracture entirely distal to the tip of her well-fixed cementless femoral stem.

According to the Vancouver classification, what is the type and the most appropriate treatment?

. Type B1; open reduction and internal fixation with cables and a lateral locking plate
. Type B2; revision to a long cementless stem
. Type B3; revision with a proximal femoral replacement
. Type C; open reduction and internal fixation with a lateral locking plate
. Type A; non-operative management with touch-down weight bearing

Correct Answer & Explanation

. Type B1; open reduction and internal fixation with cables and a lateral locking plate

Explanation

A fracture distal to the tip of the stem is a Vancouver Type C fracture. The treatment of choice is open reduction and internal fixation, typically utilizing a plate that overlaps the stem proximally to prevent a stress riser at the transition zone.

Question 5242

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient with ankylosing spondylitis is scheduled for a bilateral total hip arthroplasty. To prevent heterotopic ossification (HO), the surgeon plans to administer localized radiation therapy. When is the optimal timing for this prophylaxis?

. 1 week preoperatively
. Between 24 hours preoperatively and 72 hours postoperatively
. 5 days postoperatively
. Intraoperatively prior to closure
. 2 weeks postoperatively

Correct Answer & Explanation

. 1 week preoperatively

Explanation

Radiation therapy is highly effective for preventing heterotopic ossification. The optimal window for administration is either within 24 hours preoperatively or within 72 hours postoperatively (typically 700-800 cGy in a single fraction). Efficacy drops significantly outside this window.

Question 5243

Topic: Total Hip Arthroplasty (THA)

A 62-year-old male presents with groin pain and swelling 6 years after a metal-on-polyethylene total hip arthroplasty. Serum cobalt and chromium levels are elevated. Aspiration yields sterile fluid with a high macrophage count. Which of the following implant characteristics is most associated with this condition?

. Large diameter (>= 36mm) metal head on a standard trunnion
. Ceramic head on a titanium trunnion
. Highly cross-linked polyethylene liner
. Cemented femoral stem
. Increased acetabular cup anteversion

Correct Answer & Explanation

. Large diameter (>= 36mm) metal head on a standard trunnion

Explanation

This presentation describes mechanically assisted crevice corrosion (trunnionosis) at the modular head-neck junction. Risk factors include large diameter metal heads, which increase the torsional forces on the taper, mixed metal couples, and certain taper designs.

Question 5244

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following histologic findings is considered the hallmark of an adverse local tissue reaction (ALTR) secondary to metal hypersensitivity (ALVAL) in a patient with a modular total hip arthroplasty?

. Abundant neutrophils and fibrinous exudate
. Dense perivascular lymphocytic infiltrate with tissue necrosis
. Sheets of lipid-laden macrophages (foam cells)
. Non-caseating granulomas with multinucleated giant cells
. Extensive eosinophilic infiltration

Correct Answer & Explanation

. Abundant neutrophils and fibrinous exudate

Explanation

Aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) is characterized histologically by a dense perivascular infiltrate of lymphocytes (predominantly T-cells), plasma cells, and macrophages, often accompanied by tissue necrosis. This indicates a Type IV hypersensitivity reaction.

Question 5245

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old male presents with isolated medial compartment knee osteoarthritis. He is being evaluated for a medial unicompartmental knee arthroplasty (UKA). Which of the following is considered an absolute contraindication to a mobile-bearing UKA?

. Age less than 60 years
. Weight greater than 90 kg
. Deficient anterior cruciate ligament (ACL)
. Flexion contracture of 10 degrees
. Asymptomatic patellofemoral osteoarthritis

Correct Answer & Explanation

. Age less than 60 years

Explanation

An intact anterior cruciate ligament (ACL) is considered an absolute prerequisite for a mobile-bearing UKA. ACL deficiency leads to excessive anterior tibial translation, resulting in abnormal kinematics, bearing spin-out, and accelerated wear.

Question 5246

Topic: 3. Adult Reconstruction (Hip & Knee)

In revision total knee arthroplasty, the Anderson Orthopaedic Research Institute (AORI) classification is used to describe bone defects. A femoral defect characterized by metaphyseal bone damage isolated to the medial condyle requiring metal augments, but with an intact joint line and functional collaterals, is classified as:

. Type 1
. Type 2A
. Type 2B
. Type 3
. Type 4

Correct Answer & Explanation

. Type 1

Explanation

The AORI classification defines Type 2 as damaged metaphyseal bone requiring augments or bone graft. Type 2A involves one condyle (femur) or plateau (tibia), whereas Type 2B involves both. Type 1 is intact metaphysis, and Type 3 involves deficient metaphysis compromising ligaments.

Question 5247

Topic: 3. Adult Reconstruction (Hip & Knee)

According to the American Academy of Orthopaedic Surgeons (AAOS) clinical practice guidelines, which of the following patients undergoing an elective primary total hip arthroplasty is best suited for aspirin alone as a venous thromboembolism (VTE) prophylaxis?

. A 55-year-old with a previous history of deep vein thrombosis
. A 60-year-old with an active malignancy
. A 70-year-old with a known factor V Leiden mutation
. A 65-year-old healthy patient with no known prior VTE
. A 50-year-old patient who sustained an intraoperative vascular injury

Correct Answer & Explanation

. A 55-year-old with a previous history of deep vein thrombosis

Explanation

Current AAOS guidelines support the use of aspirin for VTE prophylaxis in standard-risk patients undergoing primary THA and TKA. Patients with a high risk for VTE (prior history, known coagulopathy, active malignancy) should receive more potent pharmacologic prophylaxis.

Question 5248

Topic: 3. Adult Reconstruction (Hip & Knee)

In a total knee arthroplasty for a patient with a long-standing fixed valgus deformity, the surgeon utilizes a gap-balancing technique. After the initial bone cuts, the lateral side is tight in extension but symmetric and balanced in flexion. Release of which of the following structures is most appropriate as the first step to balance this specific mismatch?

. Iliotibial band
. Popliteus tendon
. Lateral collateral ligament
. Lateral head of the gastrocnemius
. Biceps femoris

Correct Answer & Explanation

. Iliotibial band

Explanation

The iliotibial (IT) band is the primary lateral stabilizer in extension and becomes relatively lax in flexion. Therefore, isolated tightness in the lateral extension gap with a balanced flexion gap is best addressed by releasing or pie-crusting the IT band. Releasing the popliteus or LCL would inappropriately affect the flexion gap.

Question 5249

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old male with a metal-on-metal total hip arthroplasty presents with progressive groin pain and a palpable anterior mass. MRI reveals a solid and cystic periprosthetic collection. Histological analysis of the tissue in this condition (ALVAL) is most likely to demonstrate:

. Intense neutrophil infiltration with intracellular bacteria
. Perivascular lymphocytic infiltrate with plasma cells and macrophages
. Sheets of foamy macrophages containing abundant polyethylene particles
. Birefringent rhomboid crystals under polarized light
. Multinucleated giant cells with large ceramic shards

Correct Answer & Explanation

. Intense neutrophil infiltration with intracellular bacteria

Explanation

Aseptic Lymphocytic Vasculitis-Associated Lesion (ALVAL) is a delayed type IV hypersensitivity reaction to metal ions (cobalt and chromium) seen in metal-on-metal implants. Histologically, it is characterized by a dense perivascular lymphocytic infiltrate, plasma cells, and macrophage accumulation, distinguishing it from particulate-induced foreign-body granulomatous osteolysis.

Question 5250

Topic: Total Hip Arthroplasty (THA)

A 45-year-old active male underwent a THA with a ceramic-on-ceramic bearing. Three years postoperatively, he complains of an audible squeaking sound from his hip when walking or bending. Which of the following component positions is most strongly associated with the biomechanical phenomenon causing this sound?

. Excessive femoral anteversion
. Acetabular cup retroversion and edge loading
. Decreased global femoral offset
. Acetabular cup abduction angle < 35 degrees
. Placement of the center of rotation medial to the Kohler line

Correct Answer & Explanation

. Excessive femoral anteversion

Explanation

Squeaking in ceramic-on-ceramic bearings is strongly associated with edge loading, which disrupts the fluid lubrication film between the articular surfaces. Edge loading is often caused by malpositioning of the acetabular cup, particularly increased inclination (steep cup) or retroversion, which leads to stripe wear and subsequent squeaking.

Question 5251

Topic: 3. Adult Reconstruction (Hip & Knee)
In revision total knee arthroplasty, management of severe metaphyseal bone defects (AORI Type III) often requires highly porous metaphyseal cones or sleeves. A major biomechanical difference of metaphyseal sleeves compared to traditional unlinked cones is that sleeves:
. Are exclusively cemented into the host bone
. Are rotationally unconstrained from the femoral or tibial stem
. Provide modular, linked fixation to the stem via a Morse taper
. Rely completely on diaphyseal stem engagement for axial stability
. Do not allow for biologic ingrowth from the host bone

Correct Answer & Explanation

. Provide modular, linked fixation to the stem via a Morse taper

Explanation

Metaphyseal sleeves are modular components that link directly to the revision stem and articular components via a Morse taper, allowing them to directly transfer loads to the metaphysis. Traditional porous cones are independent of the implant; they fill the bone defect, and the stem is subsequently cemented through the cone.

Question 5252

Topic: Total Knee Arthroplasty (TKA)

A 72-year-old female presents with a chronic patellar tendon rupture 3 years after a primary TKA. Her components are radiographically well-fixed. She has an active extensor lag of 40 degrees. According to recent clinical evidence, which of the following techniques offers the lowest rate of re-rupture and clinical failure for chronic extensor mechanism disruption in TKA?

. Primary end-to-end repair with heavy nonabsorbable sutures
. Autologous semitendinosus and gracilis graft augmentation
. Gastrocnemius rotational flap without synthetic augmentation
. Achilles tendon allograft with a calcaneal bone block
. Extensor mechanism reconstruction using synthetic Marlex mesh

Correct Answer & Explanation

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

Explanation

Chronic extensor mechanism disruption post-TKA is a devastating complication. Recent literature strongly supports the use of synthetic mesh (such as Marlex) over traditional Achilles allografts, as mesh reconstruction has demonstrated significantly lower rates of mechanical failure, re-rupture, and infection.

Question 5253

Topic: Total Knee Arthroplasty (TKA)

Kinematic alignment in total knee arthroplasty aims to restore the patient's pre-arthritic, native joint lines in all three planes. Compared to traditional mechanical alignment, kinematic alignment typically results in which of the following component positions?

. The femoral component is placed in greater external rotation relative to the posterior condylar axis
. The tibial component is placed in strict 90-degree alignment to the mechanical axis
. The joint line is elevated significantly to balance the posterior cruciate ligament
. The tibial component is placed in slight varus relative to the mechanical axis
. The femoral component is placed in valgus relative to the anatomic axis

Correct Answer & Explanation

. The femoral component is placed in greater external rotation relative to the posterior condylar axis

Explanation

Traditional mechanical alignment cuts the tibia perpendicular (0 degrees) to the mechanical axis. Kinematic alignment aims to replicate the native anatomy, which typically features a joint line with about 3 degrees of varus. Therefore, the tibial component is placed in slight varus relative to the mechanical axis. The femur is aligned parallel to the posterior condylar axis (0 degrees of rotation), rather than externally rotated as in mechanical alignment.

Question 5254

Topic: Total Hip Arthroplasty (THA)
A 75-year-old male requires a revision THA. Preoperative radiographs reveal a loose femoral stem with severe diaphyseal bone loss, a completely absent isthmus, and less than 4 cm of intact diaphyseal bone for distal fixation. According to the Paprosky classification, this is a Type IIIB defect. Which of the following femoral components is the most appropriate workhorse for this reconstruction?
. Fully porous-coated cylindrical non-modular stem
. Cemented long-stem revision prosthesis
. Modular fluted tapered titanium stem
. Standard geometry proximally coated wedge stem
. Impaction bone grafting with a standard short stem

Correct Answer & Explanation

. Modular fluted tapered titanium stem

Explanation

A Paprosky IIIB defect implies inadequate diaphyseal bone (<4 cm of 'scratch fit') to reliably support a fully porous-coated cylindrical stem. Modular fluted tapered titanium stems are the preferred choice, as their flutes provide rotational stability and the taper provides axial stability in the distal diaphyseal bone, bypassing the deficient proximal bone.

Question 5255

Topic: 3. Adult Reconstruction (Hip & Knee)

Performing a total hip arthroplasty in a patient with active Paget's disease of the pelvis and proximal femur is associated with a significantly increased risk of which of the following specific perioperative complications?

. Aseptic loosening due to impaired initial bone ingrowth
. Excessive intraoperative and postoperative hemorrhage
. Massive heterotopic ossification bridging the joint
. Acute periprosthetic joint infection from impaired immunity
. Recurrent dislocation due to inherent soft tissue laxity

Correct Answer & Explanation

. Aseptic loosening due to impaired initial bone ingrowth

Explanation

Active Paget's disease is characterized by markedly increased osteoclastic and osteoblastic activity, leading to highly vascularized bone. Surgery during the active phase (elevated alkaline phosphatase) is associated with massive intraoperative hemorrhage. Preoperative administration of bisphosphonates is recommended to decrease disease activity and bleeding risk.

Question 5256

Topic: Total Knee Arthroplasty (TKA)

During a mechanically aligned primary TKA using a measured resection and gap balancing technique, the surgeon evaluates the gaps after the distal femoral and proximal tibial cuts. The extension gap measures 12 mm, while the flexion gap measures 18 mm. What is the most appropriate surgical step to balance the knee?

. Downsize the femoral component
. Resect additional distal femur
. Upsize the femoral component
. Decrease the posterior slope of the tibial cut
. Release the posterior cruciate ligament

Correct Answer & Explanation

. Downsize the femoral component

Explanation

The knee is tight in extension (12 mm) and loose in flexion (18 mm). To equalize the gaps, the extension gap must be enlarged without affecting the flexion gap. Resecting an additional 6 mm of the distal femur will increase the extension gap to 18 mm. The surgeon can then use an 18 mm polyethylene insert to balance both gaps perfectly.

Question 5257

Topic: Total Hip Arthroplasty (THA)
A 72-year-old male presents with a loose acetabular component. Imaging demonstrates an inferiorly migrated teardrop, a fracture line extending through the posterior column, and complete separation between the superior and inferior halves of the hemipelvis. What is the preferred contemporary management for this severe defect?
. Paprosky type IIIA defect; treat with a standard oversized hemispherical cup
. Paprosky type IIIB defect; treat with an unconstrained jumbo cup
. Pelvic discontinuity; treat with posterior column plating alone
. Pelvic discontinuity; treat with rigid spanning fixation such as a cup-cage construct or acetabular distraction with porous metal
. Paprosky type IIC defect; treat with a superior metal augment

Correct Answer & Explanation

. Pelvic discontinuity; treat with rigid spanning fixation such as a cup-cage construct or acetabular distraction with porous metal

Explanation

Complete separation of the superior and inferior hemipelvis is a pelvic discontinuity. It requires reconstruction that spans and rigidly fixes the superior and inferior segments. Contemporary techniques include custom triflange components, cup-cage constructs, or the acetabular distraction technique utilizing highly porous tantalum cups with augments to bridge the gap.

Question 5258

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient is evaluated for a painful TKA one year post-operatively. Serum labs show an elevated CRP (15 mg/L) and ESR (45 mm/hr). Joint aspiration yields 2,500 WBC/uL with 75% PMNs. The synovial fluid alpha-defensin immunoassay is positive. Using the 2018 MSIS (ICM) criteria scoring system, what is the correct diagnosis?

. Cannot be determined without a positive tissue culture
. Highly suggestive of adverse local tissue reaction to metal
. Definite periprosthetic joint infection
. Probable periprosthetic joint infection
. Aseptic loosening with inflammatory synovitis

Correct Answer & Explanation

. Cannot be determined without a positive tissue culture

Explanation

According to the 2018 MSIS/ICM criteria, a score of >= 6 indicates a definite PJI. Points are awarded as follows: Elevated CRP >10 mg/L (2 pts), Elevated ESR >30 mm/hr (1 pt), Positive alpha-defensin (3 pts). Total = 6 points. Even though WBC and PMN% did not meet the classical thresholds (WBC >3000, PMN >80%), the combined score reaches 6, confirming definite PJI.

Question 5259

Topic: Total Knee Arthroplasty (TKA)

A 60-year-old female presents with a painful 'catch' and an audible popping sensation when extending her knee from 40 degrees of flexion to full extension, occurring one year after a posterior-stabilized (PS) TKA. What is the fundamental pathomechanics of this specific condition?

. Entrapment of the patellar tendon in the tibial polyethylene articulation
. Fibrous nodule formation at the superior pole of the patella catching in the intercondylar notch of the femoral component
. Lateral subluxation of the patella out of the trochlear groove due to component internal rotation
. Impingement of the posterior capsule on the central stabilizing post of the polyethylene insert
. Global overstuffing of the patellofemoral joint causing excessive retinacular tension

Correct Answer & Explanation

. Entrapment of the patellar tendon in the tibial polyethylene articulation

Explanation

The clinical presentation is classic for Patellar Clunk Syndrome, which occurs almost exclusively in posterior-stabilized (PS) knees. It is caused by the formation of a fibrous nodule at the junction of the superior pole of the patella and the quadriceps tendon. As the knee extends from flexion, this nodule catches in the intercondylar box of the femoral component, then painfully 'clunks' out.

Question 5260

Topic: 3. Adult Reconstruction (Hip & Knee)
Highly cross-linked polyethylene (HXLPE) has become the standard bearing surface in total hip arthroplasty due to its remarkable wear properties. What is the primary mechanical trade-off associated with the increased cross-linking process compared to conventional UHMWPE?
. Increased susceptibility to third-body volumetric wear
. Decreased fatigue strength, ductility, and fracture toughness
. Dramatically increased rates of osteolysis despite lower wear
. Decreased oxidative stability leading to rapid delamination
. Increased coefficient of friction causing early trunnion failure

Correct Answer & Explanation

. Decreased fatigue strength, ductility, and fracture toughness

Explanation

Irradiating polyethylene breaks molecular bonds and creates free radicals, which then recombine to form cross-links. While this significantly improves wear resistance, the structural alterations decrease the material's mechanical properties, specifically its fatigue strength, ductility, and fracture toughness, increasing the risk of mechanical failure (e.g., rim fracture) under high stress.

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