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 501
Topic: 3. Adult Reconstruction (Hip & Knee)
Following a direct lateral (Hardinge) approach for total hip arthroplasty, a patient presents with a persistent Trendelenburg gait. There is no evidence of abductor tendon avulsion on MRI. Iatrogenic injury to which nerve is the most likely cause, and what technical error typically leads to this complication?
Correct Answer & Explanation
. Superior gluteal nerve; extending the muscular split greater than 5 cm proximal to the greater trochanter
Explanation
The superior gluteal nerve innervates the abductors and crosses the gluteus medius approximately 3-5 cm proximal to the greater trochanter. Extending the proximal split of the Hardinge approach beyond 5 cm risks denervating the anterior portion of the gluteus medius and minimus.
Question 502
Topic: 3. Adult Reconstruction (Hip & Knee)
A 65-year-old female undergoes a total hip arthroplasty via a direct lateral (Hardinge) approach. Post-operatively, she exhibits a pronounced Trendelenburg gait. Which of the following describes the most likely iatrogenic injury and the anatomic boundary violated during the surgical exposure?
Correct Answer & Explanation
. Superior gluteal nerve; splitting the gluteus medius more than 5 cm proximal to the greater trochanter
Explanation
The direct lateral (Hardinge) approach splits the gluteus medius and minimus. The superior gluteal nerve runs approximately 3-5 cm proximal to the greater trochanter, and extending the split beyond this risks denervating the anterior portion of the gluteus medius.
Question 503
Topic: Total Hip Arthroplasty (THA)
During a posterior approach (Kocher-Langenbeck) to the hip for a posterior wall acetabular fracture, the short external rotators are tagged and released. To prevent profuse bleeding and protect the vascular supply to the femoral head, care must be taken when releasing the quadratus femoris. Which vessel lies within or immediately deep to the quadratus femoris?
Correct Answer & Explanation
. Ascending branch of the medial circumflex femoral artery
Explanation
The ascending branch of the medial circumflex femoral artery lies deep to the quadratus femoris. It should be identified and protected, or the muscle release should leave a cuff of tissue to avoid vascular injury to the femoral head.
Question 504
Topic: 3. Adult Reconstruction (Hip & Knee)
A 52-year-old woman presents with non-specific right hip pain 3 years after a right metal-on-metal (MOM) hip resurfacing. Her anteroposterior (AP) radiograph is shown below. Based on the provided image and case discussion, which of the following findings is most concerning for potential complications related to her MOM resurfacing?
Correct Answer & Explanation
. A higher than recommended acetabular abduction angle (lateral opening).
Explanation
Correct Answer: CThe candidate in the case specifically notes that the anteroposterior (AP) radiograph demonstrates a higher abduction angle (lateral opening) than normal, with current recommendations for an acetabular abduction angle of 40 degrees. The discussion emphasizes that a high cup angle has been consistently reported to lead to greater wear and higher serum metal ion levels, which are direct precursors to complications like ALVAL and pseudotumours. This finding is a significant risk factor for the patient's presenting symptoms.Option A is incorrect because a divot sign is associated with impingement and repetitive bone-to-component abutment, which can cause wear. Its absence does not rule out other causes of wear or complications, and the case highlights other significant risk factors.Option B is incorrect. The case states that a small head size (less than 46mm) is a risk factor for ALVAL and pseudotumours, not protective. The candidate notes, 'the head size appears small; the current recommendations are that unless a minimum 46 mm head size can be used the procedure should not be performed because of the risks of ALVAL and pseudotumours.'Option D is incorrect. While no obvious narrowing of the neck is a positive finding, it does not mitigate the risk associated with a high abduction angle or small head size, which are explicitly linked to complications in the case.Option E is incorrect. The absence of radiolucency around the metaphyseal stem is a good sign regarding aseptic loosening, but it does not address the primary concern of metal-on-metal wear and pseudotumour formation, which are the focus of this case and are linked to cup positioning and head size.
Question 505
Topic: 3. Adult Reconstruction (Hip & Knee)
A 52-year-old woman with a 3-year history of right metal-on-metal hip resurfacing presents with non-specific right hip pain. The examiner asks about the difference between ALVAL and pseudotumour. Based on the case discussion, which statement accurately differentiates ALVAL from a pseudotumour?
Correct Answer & Explanation
. A pseudotumour is considered a more severe inflammatory reaction than ALVAL, which is characterized by metal particulate debris and localized osteolysis.
Explanation
Correct Answer: CThe case explicitly states: 'ALVAL (aseptic lymphocyte-dominated vasculitis-associated lesion) is caused by metal particulate debris. Patients present with localized hip pain and a localized osteolytic reaction. A more severe inflammatory reaction is termed a pseudotumour.' This directly supports option C.Option A is incorrect because it reverses the severity and characteristics. ALVAL is the localized osteolytic reaction, and pseudotumour is the more severe inflammatory reaction.Option B is incorrect. The case states that the origin of pseudotumours is 'probably multifactorial caused either by excessive wear, metal hypersensitivity, a combination of the two, or as yet an unknown cause.' ALVAL is caused by metal particulate debris, which can be related to wear, not exclusively hypersensitivity.Option D is incorrect. The case mentions that 'Pseudotumor-like reactions have also been reported in non-metal-on-metal bearings,' indicating they are not exclusive to MOM. ALVAL is specifically linked to metal particulate debris, which is a hallmark of MOM wear.Option E is incorrect. While Campbell et al. reported some pseudotumours with minimal wear suggesting hypersensitivity, the case also states that 'Several studies have described an association between pseudotumours and increased wear of retrieved components.' Therefore, pseudotumours are notalwaysassociated with minimal wear, and their origin is multifactorial.
Question 506
Topic: 3. Adult Reconstruction (Hip & Knee)
During the discussion of revision surgery for the pseudotumour, the examiner asks about the principles of surgery. Which of the following surgical principles is most consistent with the candidate's recommended approach for this patient?
Correct Answer & Explanation
. Thorough debridement of all abnormal soft tissue, using an uncemented metal-on-polyethylene bearing, with consideration for a constrained cup if instability is present.
Explanation
Correct Answer: CThe candidate outlines the principles of surgery: 'The pseudotumour needs to be managed with aggressive debridement of all involved soft tissue. It is important to do a thorough debridement of the abnormal tissue similar to the treatment of infection.' Regarding bearing surfaces, the candidate states: 'Although she is still relatively young I would use a metal-on-polyethylene bearing surface. A ceramic bearing surface has the potential for catastrophic fracture. We are already revising for a rare complication and we donโt want anything to go wrong again. However I would use an uncemented implant. I would keep the option of using a constrained cup open as the soft tissues may be so poorly compromised that the hip is unstable but obviously would prefer to avoid this, as components will loosen early in this situation.'Option C accurately reflects all these points: thorough debridement, uncemented metal-on-polyethylene bearing, and consideration of a constrained cup for instability.Option A is incorrect because the candidate specifically advises against a ceramic bearing surface due to fracture risk.Option B is incorrect due to 'limited debridement' (the candidate recommends aggressive/thorough) and 'cemented' (the candidate recommends uncemented).Option D is incorrect. 'Debridement only of the visible mass' is not thorough enough, and 'large metal-on-metal jumbo hip replacement' is contraindicated as a primary procedure due to metal wear and corrosion, and certainly not appropriate for revision of a MOM pseudotumour.Option E is incorrect. The case emphasizes urgent revision surgery due to the risk of extensive soft tissue destruction, not conservative management.
Question 507
Topic: 3. Adult Reconstruction (Hip & Knee)
The examiner challenges the candidate on the utility of MOM hip resurfacing, suggesting that conventional THA works equally well. The candidate defends resurfacing by listing its advantages. Which of the following is NOT listed as an advantage of MOM hip resurfacing in the case discussion?
Correct Answer & Explanation
. Lower revision rates compared to conventional THA.
Explanation
Correct Answer: DThe candidate lists several advantages of MOM hip resurfacings: 'better restoration of hip biomechanics, improved proprioceptive feedback, improved wear characteristics with no PE-induced osteolysis, increased levels of postsurgical activity, greater range of movement, reduced risk of dislocation, improved femoral bone stock mass because the neck and most of the head are retained and ease of conversion to a THA if the implant should fail.'However, when discussing outcomes, the case explicitly states: 'There is a higher revision rate in hip resurfacing compared with conventional THA.' Therefore, lower revision rates are NOT an advantage; in fact, the opposite is true.Options A, B, C, and E are all directly listed as advantages by the candidate in the case.
Question 508
Topic: 3. Adult Reconstruction (Hip & Knee)
The examiner asks about the outcomes of hip resurfacing compared with conventional THA. Based on the case discussion, which statement accurately summarizes the comparative outcomes?
Correct Answer & Explanation
. Both procedures yield identical Harris hip scores, but hip resurfacing is associated with a higher percentage of patients involved in high-demand activities and a higher revision rate.
Explanation
Correct Answer: BThe case directly addresses this: 'Several recent studies report identical Harris hip scores but a greater percentage of patients with resurfacing involved in high demand activities. There is a higher revision rate in hip resurfacing compared with conventional THA.'Option A is incorrect because hip resurfacing does not have lower revision rates; it has higher revision rates.Option C is incorrect. The candidate lists 'better restoration of hip biomechanics' and 'improved proprioceptive feedback' as advantages of MOM hip resurfacing, not conventional THA.Option D is incorrect. While hip resurfacing does have a reduced risk of dislocation, it is associated with 'no PE-induced osteolysis' because it's a metal-on-metal bearing, not a higher incidence of it.Option E is incorrect. The candidate lists 'improved femoral bone stock mass because the neck and most of the head are retained' and 'ease of conversion to a THA if the implant should fail' as advantages of MOM hip resurfacing, not conventional THA.
Question 509
Topic: 3. Adult Reconstruction (Hip & Knee)
A 65-year-old woman with Paget's disease of the pelvis and proximal femur is undergoing preoperative planning for a total hip arthroplasty. Her radiographs show significant varus deformity of the proximal femur and a protrusio deformity of the acetabulum. Which of the following is a key consideration for the femoral component during this surgery?
Correct Answer & Explanation
. C. Planning for a reduction osteotomy or the use of modular stems may be necessary for severe deformity.
Explanation
Correct Answer: CThe case states: 'Varus deformity of the proximal end of the femur predisposes to varus placement of the femoral component.' It further elaborates on managing severe deformity: 'In the majority of patients with Pagetโs THA can be performed without need for osteotomy. However, if deformity is severe, precluding implantation with a standard stem, then planning for reduction osteotomy to correct the deformity and/or the use of modular stems must be made preoperatively.' Therefore, for severe deformity, osteotomy or modular stems are key considerations.Option A is incorrect; the case states varus deformity predisposes tovarusplacement, not valgus. Option B is incorrect, as the case explicitly mentions that severe deformity may preclude implantation with a standard stem, necessitating other approaches. Option D is incorrect; the choice between cemented and uncemented is discussed, but varus deformity itself does not contraindicate cementless components, though severe deformity might influence the need for osteotomy regardless of fixation type. Option E is incorrect; protrusio deformity complicates surgery, and marked protrusio can make hip dislocation very difficult, not simplify femoral component insertion.
Question 510
Topic: 3. Adult Reconstruction (Hip & Knee)
A 62-year-old patient with Paget's disease is being considered for total hip arthroplasty. The orthopedic surgeon is debating between a cemented and uncemented femoral component. The patient is otherwise healthy, and the bone is noted to be very sclerotic. Which of the following statements BEST reflects the current understanding and recommendations regarding implant choice in Paget's disease?
Correct Answer & Explanation
. C. Some surgeons prefer cementless components, especially when bone is very sclerotic, and adjuvant acetabular screws are recommended for cementless cups.
Explanation
Correct Answer: CThe case discusses the evolving trend in implant choice: 'Although previous studies have recommended the use of cement in the last 20 years there has been a trend to use uncemented components.' It specifically states: 'Some surgeons prefer cementless components especially when bone is very sclerotic or a concurrent osteotomy is done. Extremely sclerotic bleeding bone will make interdigitation of cement difficult and cement extravasation into the fracture gaps may occur after osteotomy. If using a cementless cup the use of adjuvant acetabular screws is recommended.'Option A is incorrect; while historically recommended, there's a trend towards uncemented, and the choice is now more nuanced. Option B is incorrect; the case explicitly states: 'Patients with Pagetโs disease are not known to have compromised ability for fracture healing and these patients progress through the biological process of fracture healing at normal speed.' This supports ingrowth. Option D is incorrect; the case states: 'The worry that the altered morphology of pagetoid bone adversely influences ingrowth into cementless implants has not been borne out in practice.' Option E is incorrect; the examiner explicitly states, 'No, I am not aware of an increased risk of dislocation' in Paget's disease post-THA.
Question 511
Topic: 3. Adult Reconstruction (Hip & Knee)
A 68-year-old woman with Paget's disease of the left hemipelvis and proximal femur is being evaluated for persistent hip pain after a total hip arthroplasty (THA). Her alkaline phosphatase levels remain elevated. Which of the following postoperative complications is NOT specifically mentioned as an increased risk in Paget's disease patients following THA in the provided text?
Correct Answer & Explanation
. E. Dislocation.
Explanation
Correct Answer: EThe examiner specifically states: 'No, I am not aware of an increased risk of dislocation.' This directly contradicts the idea of an increased risk of dislocation. The candidate initially suggests dislocation, but the examiner corrects this.The other options are all mentioned as potential complications:Heterotopic ossification:'There is a reported greater incidence of heterotopic ossification.'Osteolysis:'However, several studies have documented osteolysis following THA in patients with Pagetโs disease.'Periprosthetic fracture:'Other complications include periprosthetic fracture around total hip implants...'Continuation of bone pain:'...and the continuation of bone pain following arthroplasty...'Therefore, dislocation is the only complication listed that is explicitly stated NOT to have an increased risk in Paget's disease patients following THA.
Question 512
Topic: 3. Adult Reconstruction (Hip & Knee)
A 68-year-old female presents with groin pain and a leg length discrepancy 6 months following a cemented total hip arthroplasty for osteoarthritis. She reports increasing pain with ambulation and night pain. Radiographs demonstrate lucencies greater than 2mm around the femoral stem and acetabular component in multiple zones, with some subsidence of the femoral stem. Laboratory markers (ESR, CRP, WBC count) are within normal limits. Aspiration of the hip joint yields a clear, viscous fluid. What is the most likely diagnosis?
Correct Answer & Explanation
. Aseptic loosening
Explanation
Correct Answer: BThe clinical picture of increasing groin pain, leg length discrepancy, and classic radiographic lucencies (greater than 2mm in multiple zones) around both components, coupled with normal inflammatory markers and a clear joint aspirate, strongly points towards aseptic loosening. Periprosthetic joint infection would typically present with elevated inflammatory markers and potentially purulent aspirate, although chronic low-grade infections can be subtle. Heterotopic ossification can cause pain and stiffness but is usually identifiable on X-ray as mature bone formation and does not typically present with component lucencies. Stress shielding is a radiographic finding (bone resorption around the implant) that contributes to loosening but is not the primary diagnosis. Component impingement would cause activity-related pain and potentially dislocation, but not the specific radiographic findings of widespread lucency and subsidence.
Question 513
Topic: 3. Adult Reconstruction (Hip & Knee)
A 72-year-old male with a history of hypertension and osteoporosis sustains a fall, resulting in a periprosthetic fracture of the femur around the stem of his 10-year-old cemented total knee arthroplasty. Radiographs reveal a Vancouver Type B2 fracture. What is the most appropriate management?
Correct Answer & Explanation
. Revision total knee arthroplasty with a longer, cemented stem
Explanation
Correct Answer: DA Vancouver Type B2 periprosthetic fracture involves a fracture around or distal to a stable femoral stem, with a loose femoral component. Given the described lucencies around the stem and the fracture, the femoral component is likely loose. Therefore, revision of the femoral component with a longer, cemented stem is the appropriate treatment, providing stability both proximally (by bypassing the fracture) and distally (by engaging healthy bone). Non-operative management is typically reserved for stable, non-displaced fractures (e.g., Vancouver Type C or some Type A). ORIF alone is insufficient as the component is loose. An uncemented stem might be considered in younger, healthier patients with good bone quality, but a cemented stem is often preferred in older patients with osteoporosis for immediate stability. Knee fusion is a salvage procedure typically reserved for failed revisions or severe infection.
Question 514
Topic: 3. Adult Reconstruction (Hip & Knee)
A 45-year-old active male is considering hip arthroplasty for end-stage osteoarthritis. Which of the following is considered an absolute contraindication to metal-on-metal hip resurfacing?
Correct Answer & Explanation
. Renal insufficiency
Explanation
Renal insufficiency is an absolute contraindication to metal-on-metal hip resurfacing. Metal ions such as cobalt and chromium are primarily excreted by the kidneys, and impaired renal function leads to toxic systemic accumulation.
Question 515
Topic: 3. Adult Reconstruction (Hip & Knee)
What is the predominant histological feature of Aseptic Lymphocyte-dominated Vasculitis-Associated Lesion (ALVAL) in a failing metal-on-metal hip arthroplasty?
Correct Answer & Explanation
. Perivascular lymphocytic infiltrate
Explanation
ALVAL represents a delayed Type IV hypersensitivity reaction to metal wear debris. It is histologically characterized by a dense perivascular infiltration of T-lymphocytes and varying degrees of tissue necrosis.
Question 516
Topic: Total Hip Arthroplasty (THA)
In metal-on-metal hip resurfacing, which of the following component malpositionings most significantly increases the risk of accelerated edge-loading and elevated serum metal ions?
Correct Answer & Explanation
. Acetabular inclination of 55 degrees
Explanation
Excessive acetabular inclination (typically >50-55 degrees) leads to edge-loading, which disrupts the fluid film lubrication. This results in accelerated wear and significantly elevated serum cobalt and chromium levels.
Question 517
Topic: 3. Adult Reconstruction (Hip & Knee)
An asymptomatic 50-year-old male is evaluated 5 years after a metal-on-metal hip resurfacing. Routine screening reveals a cobalt level of 10 ppb (normal <1 ppb). What is the most appropriate next step in management?
Correct Answer & Explanation
. Metal Artifact Reduction Sequence (MARS) MRI of the hip
Explanation
In asymptomatic patients with elevated metal ions (>7 ppb), cross-sectional imaging with MARS MRI is recommended to screen for subclinical pseudotumors or adverse local tissue reactions.
Question 518
Topic: Total Hip Arthroplasty (THA)
Systemic toxicity from cobalt and chromium ions following metal-on-metal hip resurfacing can manifest with which of the following classic constellations of symptoms?
Correct Answer & Explanation
. Cardiomyopathy, visual impairment, and hearing loss
Explanation
Systemic cobalt toxicity (cobaltism) can cause devastating complications including cardiomyopathy, polyneuropathy, visual impairment, hearing loss, and cognitive decline.
Question 519
Topic: 3. Adult Reconstruction (Hip & Knee)
A 40-year-old female undergoes a right metal-on-metal hip resurfacing. Intraoperatively, the femoral neck is inadvertently notched superiorly. This technical error places the patient at highest risk for which of the following complications?
Correct Answer & Explanation
. Early femoral neck fracture
Explanation
Superior notching of the femoral neck during hip resurfacing creates a stress riser in a region of high tensile forces. This significantly predisposes the patient to a postoperative femoral neck fracture.
Question 520
Topic: 3. Adult Reconstruction (Hip & Knee)
What is the most characteristic finding on a Metal Artifact Reduction Sequence (MARS) MRI indicative of a pseudotumor around a metal-on-metal hip implant?
Correct Answer & Explanation
. Thick-walled cystic or solid soft tissue mass communicating with the joint
Explanation
Pseudotumors typically appear on MARS MRI as thick-walled cystic fluid collections or solid necrotic masses. They frequently communicate with the joint space and can invade surrounding musculature.
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