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 2421
Topic: 3. Adult Reconstruction (Hip & Knee)
Following a primary total knee arthroplasty, a patient experiences isolated patellar clunk syndrome. Which of the following implant designs or technical factors is most closely associated with this phenomenon?
Correct Answer & Explanation
. Posterior-stabilized (PS) femoral component with a high intercondylar box
Explanation
Patellar clunk syndrome occurs in posterior-stabilized TKA when a fibrotic nodule forms at the superior pole of the patella. During extension, this nodule catches in the intercondylar box of the femoral component and "clunks" out as the knee reaches full extension.
Question 2422
Topic: Total Hip Arthroplasty (THA)
A 50-year-old active male underwent a THA 3 years ago and now complains of an audible squeaking sound during hip flexion.
Which of the following factors is most strongly associated with squeaking in ceramic-on-ceramic total hip arthroplasty?
Correct Answer & Explanation
. Component malposition leading to edge loading
Explanation
Squeaking is a specific complication associated with hard-on-hard bearings, particularly ceramic-on-ceramic THA. The most significant biomechanical cause is edge loading, which occurs due to micro-separation, impingement, or component malposition (e.g., steep cup abduction angles or insufficient anteversion). This results in loss of fluid film lubrication and stripe wear, ultimately causing the squeak.
Question 2423
Topic: Total Knee Arthroplasty (TKA)
Following a standard primary Total Knee Arthroplasty (TKA), the surgeon notes lateral patellar maltracking during the trial reduction.
Which of the following component malrotations is most likely responsible for causing lateral patellar maltracking?
Correct Answer & Explanation
. Internal rotation of the femoral component and internal rotation of the tibial component
Explanation
Lateral patellar maltracking in TKA is primarily caused by an increase in the Q-angle. Internal rotation of the femoral component medializes the trochlear groove relative to the extensor mechanism. Internal rotation of the tibial component medializes the tibial tubercle. Both errors functionally increase the Q-angle and lead to lateral patellar tracking or subluxation.
Question 2424
Topic: 3. Adult Reconstruction (Hip & Knee)
During a primary total hip arthroplasty (THA), a multi-hole hemispherical acetabular component is used. The surgeon plans to place adjuvant screws for initial stability. Based on the Wasilewski quadrant system, placing a screw in the anterior-inferior quadrant places which of the following structures at highest risk of injury?
Correct Answer & Explanation
. Sciatic nerve
Explanation
According to the Wasilewski quadrant system (divided by a line from the ASIS through the center of the acetabulum and a perpendicular line), the posterior-superior quadrant is the safe zone for screw placement with the best bone stock. The anterior-superior quadrant places the external iliac artery and vein at risk. The anterior-inferior quadrant places the obturator nerve and vessels at risk. The posterior-inferior quadrant places the internal pudendal and inferior gluteal vessels at risk.
Question 2425
Topic: 3. Adult Reconstruction (Hip & Knee)
During a primary Total Knee Arthroplasty (TKA) for a patient with a severe varus deformity, the surgeon evaluates the gaps and notes that the medial side is tight in both flexion and extension. To correctly balance the knee, the surgeon must perform a medial release. According to the standard stepwise sequence, which of the following structures should be released first?
Correct Answer & Explanation
. Deep medial collateral ligament (MCL)
Explanation
The classic sequential medial release for a fixed varus deformity in TKA progresses from deep to superficial and anterior to posterior. The first structure released is the deep MCL (meniscofemoral and meniscotibial ligaments) via excision of the medial meniscus and release from the proximal tibia. If further release is needed, the posteromedial capsule, followed by the semimembranosus, superficial MCL, and finally the pes anserinus are progressively elevated or released.
Question 2426
Topic: 3. Adult Reconstruction (Hip & Knee)
During a posterolateral approach for a total hip arthroplasty, the short external rotators are detached. The primary blood supply to the native femoral head is the medial femoral circumflex artery (MFCA). Where is the main branch of the MFCA located relative to the short external rotators?
Correct Answer & Explanation
. Superior to the upper border of the quadratus femoris and deep to the obturator externus
Explanation
The main branch of the medial femoral circumflex artery (MFCA) consistently runs superior to the upper border of the quadratus femoris and deep (anterior) to the obturator externus tendon. During the posterolateral approach, leaving the obturator externus intact or avoiding dissection inferior to the quadratus femoris protects the MFCA.
Question 2427
Topic: 3. Adult Reconstruction (Hip & Knee)
In total hip arthroplasty, the choice of bearing surface can impact the long-term survivorship of the implant. Which of the following bearing surface combinations exhibits the lowest in vitro volumetric wear rate?
Correct Answer & Explanation
. Ceramic on ceramic
Explanation
Ceramic-on-ceramic (CoC) bearing surfaces have the lowest volumetric wear rate and produce the smallest, least biologically active wear particles among all conventional THA bearing combinations. They are extremely hard and scratch-resistant, though they carry a unique risk of squeaking and catastrophic component fracture.
Question 2428
Topic: Total Hip Arthroplasty (THA)
During a total hip arthroplasty via a posterior approach, the surgeon decides to use a high-offset femoral stem rather than a standard-offset stem. Assuming neck angle and leg length remain constant, what is the primary biomechanical effect of this change?
Correct Answer & Explanation
. Decreased abductor tension and increased joint reactive force
Explanation
Increasing the femoral offset lateralizes the proximal femur. This increases the lever arm (moment arm) of the abductor musculature. Because the abductors have a mechanical advantage, they require less force to balance the pelvis during single-leg stance. A reduction in abductor muscle force proportionally decreases the overall joint reactive force across the hip.
Question 2429
Topic: 3. Adult Reconstruction (Hip & Knee)
A 72-year-old female presents with a painful total knee arthroplasty 3 years post-operatively. Synovial fluid analysis is performed to rule out periprosthetic joint infection (PJI). Which of the following biomarkers, released by neutrophils in response to pathogens, is highly specific for PJI and can be tested via a synovial fluid immunoassay?
Correct Answer & Explanation
. Alpha-defensin
Explanation
Alpha-defensin is an antimicrobial peptide released by neutrophils in response to pathogens. It has been shown to be highly sensitive and specific for diagnosing periprosthetic joint infection (PJI) when measured in synovial fluid. While serum CRP and ESR are excellent screening tools, and synovial fluid white blood cell counts are standard, alpha-defensin testing provides an excellent diagnostic adjunct, particularly when standard tests are equivocal.
Question 2430
Topic: 3. Adult Reconstruction (Hip & Knee)
A surgeon is performing a total knee arthroplasty on a severe valgus knee.
While balancing the knee in extension, the lateral compartment remains significantly tight. According to classic lateral release sequences (e.g., Krackow or Ranawat), which structure is typically released first for a tight extension gap?
Correct Answer & Explanation
. Iliotibial (IT) band
Explanation
In balancing a valgus knee, the sequence of release depends on whether the knee is tight in extension, flexion, or both. For a tight extension gap, the Iliotibial (IT) band is typically released first (often via "pie-crusting" from the inside out). The popliteus tendon is primarily a flexion stabilizer and is released if the flexion gap is disproportionately tight. The LCL is released if both are tight after initial releases.
Question 2431
Topic: 3. Adult Reconstruction (Hip & Knee)
A 65-year-old female who underwent a metal-on-metal (MoM) total hip arthroplasty 5 years ago presents with new-onset groin pain and swelling. A MARS MRI reveals a solid-cystic pseudotumor. Histological examination of the periarticular tissue demonstrates Aseptic Lymphocyte-Dominated Vasculitis-Associated Lesion (ALVAL). This pathological process is mediated by which type of immune response?
Correct Answer & Explanation
. Type IV delayed hypersensitivity
Explanation
Adverse local tissue reactions (ALTR) in metal-on-metal implants frequently manifest as ALVAL. The histological presence of a dense perivascular lymphocytic infiltrate (predominantly T-cells) characterizes a Type IV delayed hypersensitivity reaction to metal wear debris (typically cobalt and chromium ions).
Question 2432
Topic: 3. Adult Reconstruction (Hip & Knee)
Figures 10a and 10b show the radiographs of a 47-year-old man who reports pain in both shoulders. He has a history of leukemia that was treated with chemotherapy and high-dose cortisone. What is the most reliable treatment option for pain relief in this patient?
Correct Answer & Explanation
. Hemiarthroplasty
Explanation
The radiographs reveal osteonecrosis with collapse. The most reliable and durable treatment for osteonecrosis of the humeral head remains prosthetic shoulder arthroplasty. Osteonecrosis of the humeral head may be seen after the use of steroids, and there is an increasing demand for shoulder arthroplasty in young people because of the use of high-dose steroids in chemotherapy regimes for the treatment of malignant tumors. The indications for most shoulder arthrodeses today include posttraumatic brachial plexus injury, paralytic disorders in infancy, insufficiency of the deltoid muscle and rotator cuff, chronic infection, failed revision arthroplasty, severe refractory instability, and bone deficiency following resection of a tumor in the proximal aspect of the humerus. Clearly, the role of arthroscopy and related minimally invasive techniques in the treatment of humeral head osteonecrosis remains unknown. Hasan SS, Romeo AA: Nontraumatic osteonecrosis of the humeral head. J Shoulder Elbow Surg 2002;11:281-298. Hattrup SJ: Indications, technique, and results of shoulder arthroplasty in osteonecrosis. Orthop Clin North Am 1998;29:445-451.
Question 2433
Topic: 3. Adult Reconstruction (Hip & Knee)
During primary total knee arthroplasty, the trial components are in place. The extensor space is tight, but the flexion space is normal. What is the best gap balancing solution?
Correct Answer & Explanation
. Resect additional distal femoral bone.
Explanation
The first rule of total knee arthroplasty is to restore the joint line to its original location. This will ensure optimal patellofemoral biomechanics and will facilitate ligament balancing. Changes on the tibial side affect both the flexion and extension gaps equally. Changes in femoral component sizing or position affect the flexion gap only. Tibial changes affect both the flexion and extension gaps. To convert a tight extension gap to a normal flexion gap, more distal femur needs to be resected. Vince KG: Revision knee arthroplasty technique. Instr Course Lect 1993;42:325-339.
Question 2434
Topic: 3. Adult Reconstruction (Hip & Knee)
An 82-year-old woman reports right buttock pain after a car trip. Laboratory studies show an erythrocyte sedimentation rate of 30 mm/h and WBC of 4,600/mm3. Figure 34a shows a plain AP radiograph of the pelvis, and Figure 34b shows a delayed technetium Tc 99m bone scan. Management should consist of
Correct Answer & Explanation
. bed rest and pain medication.
Explanation
The radiograph shows bilateral cemented total hip arthroplasties. The acetabular components are loose bilaterally, but there has been no acute change. Therefore, it is unlikely that the acetabular loosening is contributing to the patient's pain. The bone scan is consistent with a sacral insufficiency fracture. This is best treated with bed rest and pain medication. Activity can be increased as the pain allows. Revision will not address the pain. Newhouse KE, el-Khoury GY, Buckwalter JA: Occult sacral fractures in osteopenic patients. J Bone Joint Surg Am 1992;74:1472-1477.
Question 2435
Topic: 3. Adult Reconstruction (Hip & Knee)
A 72-year-old woman with rheumatoid arthritis who underwent primary total knee arthroplasty 2 years ago has had diffuse knee pain that developed shortly after the surgery. The patient has difficulty with stair descent and arising from chairs. Evaluation for infection is negative. AP and lateral radiographs are shown in Figure 26. Management should now consist of
Correct Answer & Explanation
. revision to a posterior stabilized implant.
Explanation
The radiographs show posterior flexion instability that is the result of flexion-extension gap imbalance and/or posterior cruciate ligament incompetence after a posterior cruciate-retaining total knee arthroplasty. The radiographs also show anterior femoral displacement on the tibia. Pagnano and associates reported on a series of patients with painful total knee arthroplasties who had been previously diagnosed as having pain of unknown etiology, showing that the pain was secondary to flexion instability. Pain relief was achieved by revision to a posterior stabilized implant. Pagnano MW, Hanssen AD, Lewallen DG, Stuart MJ: Flexion instability after primary posterior cruciate retaining total knee arthroplasty. Clin Orthop 1998;356:39-46. Fehring TK, Valadie AL: Knee instability after total knee arthroplasty. Clin Orthop 1994;299:157-162.
Question 2436
Topic: 3. Adult Reconstruction (Hip & Knee)
A right-handed 44-year-old construction worker reports pain and limited range of motion in his right elbow that has limited his ability to work for the past year. Examination reveals range of motion from 60 to 90 degrees, and he has pain at the extremes of flexion and extension. Pronation and supination are minimally restricted. Anti-inflammatory drugs have failed to provide relief. A radiograph is shown in Figure 8. Management should now consist of
Correct Answer & Explanation
. ulnohumeral arthroplasty and ulnar nerve decompression.
Explanation
The radiograph reveals primary osteoarthritis of the elbow; therefore, ulnohumeral arthroplasty is the preferred procedure. Patients with severely limited preoperative elbow extension of more than 60 degrees and flexion of less than 100 degrees are at risk for ulnar nerve dysfunction postoperatively and should undergo a concomitant ulnar nerve decompression. Nonsurgical methods are unlikely to improve his chronic condition. Elbow arthroplasty is contraindicated for patients in this age group and with this diagnosis. Antuna SA, Morrey BF, Adams RA, et al: Ulnohumeral arthroplasty for primary degenerative arthritis of the elbow: Long-term outcome and complications. J Bone Joint Surg Am 2002;84:2168-2173.
Question 2437
Topic: 3. Adult Reconstruction (Hip & Knee)
Figure 33 shows the AP and lateral radiographs of an obese 58-year-old man who underwent a cementless total hip arthroplasty 6 years ago. He reports no pain, and examination reveals a normal gait and painless hip range of motion. What is the most likely diagnosis?
Correct Answer & Explanation
. Osteolysis because of polyethylene debris
Explanation
Osteolysis of an otherwise well-functioning total hip arthroplasty is a recognized complication, and its radiographic appearance is typical, as shown here. Distal osteolysis, such as that shown here, is more prevalent when there is noncircumferential sealing of the proximal femoral canal. Pellicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 175-180.
Question 2438
Topic: 3. Adult Reconstruction (Hip & Knee)
Stiffness can occur following total knee arthroplasty. What is the most appropriate management for a patient who has deteriorating arc of motion after undergoing a revision knee arthroplasty 9 months ago?
Correct Answer & Explanation
. Investigation for periprosthetic infection
Explanation
Stiffness following total knee arthroplasty can be a disabling condition. There are many reasons for loss of knee motion following total knee arthroplasty. Technical errors, such as overstuffing of the patella, malpositioning of the components, and ligamentous imbalance, are all known to result in stiffness following total knee arthroplasty. In some patients with a possible genetic predisposition, aggressive arthrofibrosis may develop and result in loss of knee motion. In any patient who has deteriorating knee motion, particularly after revision arthroplasty, deep infection should be ruled out. Although on occasion surgical intervention may be required to address knee stiffness, the outcome of revision surgery is poor if no reason for stiffness can be determined. Kim J, Nelson CL, Lotke PA: Stiffness after total knee arthroplasty: Prevalence of the complication and outcomes of revision. J Bone Joint Surg Am 2004;86:1479-1484.
Question 2439
Topic: 3. Adult Reconstruction (Hip & Knee)
A 70-year-old male presents with persistent knee pain, swelling, and purulent drainage 6 months after a total knee arthroplasty (TKA). Aspiration yields turbid fluid with 80,000 WBCs/ยตL, 95% neutrophils, and positive cultures for Staphylococcus aureus. His C-reactive protein (CRP) is 120 mg/L (normal < 5 mg/L), and ESR is 100 mm/hr. He has no other comorbidities. What is the most appropriate surgical management strategy for this patient?
Correct Answer & Explanation
. Two-stage revision arthroplasty.
Explanation
This patient presents with a chronic periprosthetic joint infection (PJI) of the knee, characterized by persistent pain, swelling, purulent drainage, high synovial fluid WBC count (80,000 WBCs/ยตL) and neutrophil percentage (95%), elevated ESR and CRP, and positive cultures for Staphylococcus aureus 6 months post-TKA. The key factors here are the chronicity of the infection (6 months), the presence of purulence, and the positive virulent organism (S. aureus). Option A (Debridement, antibiotics, and implant retention - DAIR) is generally reserved for acute PJI (within 3-6 weeks of surgery or acute hematogenous spread on a well-fixed, stable implant), with healthy soft tissues and susceptible organisms. Given the 6-month duration and purulent drainage, the biofilm is well-established, making DAIR highly unlikely to succeed. Option B (Two-stage revision arthroplasty) is considered the gold standard for chronic PJI, especially with virulent organisms, established biofilms, and significant soft tissue involvement or unknown organisms. The first stage involves complete removal of all prosthetic components, extensive debridement, and placement of an antibiotic-loaded cement spacer. After a period of intravenous antibiotics and normalization of inflammatory markers, the second stage involves spacer removal and reimplantation of a new TKA. This approach has the highest success rates for eradicating infection while preserving the possibility of a functional knee joint. Option C (One-stage revision arthroplasty) may be considered in highly selected cases of chronic PJI with less virulent organisms, good soft tissue envelopes, and known susceptibility to antibiotics, but it carries a higher risk of recurrent infection compared to two-stage revisions, especially with Staphylococcus aureus. Option D (Chronic antibiotic suppression) is typically reserved for patients who are not surgical candidates, who have low-virulence organisms, or who have failed other surgical attempts, and it does not eradicate the infection, only attempts to control it. Option E (Arthrodesis of the knee) is a salvage procedure considered when all other attempts to eradicate infection and reconstruct the joint have failed, or in patients with very poor bone stock/soft tissues, resulting in a stiff, fused knee.
Question 2440
Topic: 3. Adult Reconstruction (Hip & Knee)
A 72-year-old male with a history of a cemented total hip arthroplasty (THA) 15 years ago presents with persistent groin pain and aseptic loosening of the acetabular component. Radiographs show significant acetabular osteolysis and a Paprosky Type IIIB defect. Which of the following is the MOST appropriate reconstructive option for this acetabular defect?
Correct Answer & Explanation
. Revision with an acetabular reconstruction cage with bone graft.
Explanation
A Paprosky Type IIIB acetabular defect is characterized by massive bone loss involving โฅ50% of the host acetabulum, discontinuity of the pelvic rim, or pelvic dissociation, often with superior migration of the hip center. For such significant defects, a jumbo hemispheric cup alone is usually insufficient to provide adequate host bone coverage and primary stability. While custom triflange components can be used for severe cases, acetabular reconstruction cages combined with structural or morselized bone graft are a well-established and effective reconstructive option for Paprosky Type IIIB defects, providing stability and allowing for bone ingrowth. A standard cementless cup would fail due to insufficient host bone. Girdlestone resection arthroplasty is generally reserved for septic cases or failed revisions in very low-demand patients.
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