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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 225 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 4481

Topic: 3. Adult Reconstruction (Hip & Knee)

A 62-year-old male with a metal-on-polyethylene THA placed 7 years ago presents with new-onset anterior groin pain. Serum cobalt is elevated at 8.5 ppb, while serum chromium is normal. A MARS-MRI demonstrates a large cystic fluid collection around the hip joint. What is the most likely etiology of this patient's condition?

. Periprosthetic joint infection
. Polyethylene wear with macrophage-mediated osteolysis
. Mechanically assisted crevice corrosion (Trunnionosis)
. Adverse local tissue reaction from a metal-on-metal bearing
. Iliopsoas impingement

Correct Answer & Explanation

. Mechanically assisted crevice corrosion (Trunnionosis)

Explanation

Elevated cobalt levels with normal chromium in the setting of a metal-on-polyethylene bearing strongly suggests mechanically assisted crevice corrosion at the head-neck taper (trunnionosis). This generates an adverse local tissue reaction (ALTR) mimicking a pseudotumor.

Question 4482

Topic: 3. Adult Reconstruction (Hip & Knee)
A 68-year-old female undergoes an acetabular revision for aseptic loosening. Preoperative radiographs demonstrate superior cup migration of 3.5 cm, significant ischial osteolysis, and an intact Kohler line. Based on the Paprosky classification, which of the following is the most appropriate acetabular reconstruction strategy?
. Jumbo cementless cup alone
. Highly porous hemispherical titanium cup with a trabecular metal augment
. Impaction particulate bone grafting with a cemented polyethylene cup
. Custom triflange acetabular component
. Anti-protrusio cage with strut allograft

Correct Answer & Explanation

. Highly porous hemispherical titanium cup with a trabecular metal augment

Explanation

Superior migration greater than 3 cm with ischial osteolysis and an intact teardrop/Kohler line defines a Paprosky IIIA defect. A highly porous hemispherical cup supported by trabecular metal augments is the preferred reconstructive option to restore the joint center.

Question 4483

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old male presents with acute onset of severe hip pain and fever 3 weeks after an uncomplicated primary THA. Aspiration yields 45,000 WBCs/mcL with 92% neutrophils. Radiographs show well-fixed components. What is the most appropriate definitive surgical management?

. Suppressive intravenous antibiotics without surgery
. One-stage revision arthroplasty
. Debridement, antibiotics, and implant retention (DAIR) with modular component exchange
. Two-stage revision arthroplasty with an antibiotic spacer
. Resection arthroplasty (Girdlestone procedure)

Correct Answer & Explanation

. Debridement, antibiotics, and implant retention (DAIR) with modular component exchange

Explanation

DAIR with modular component exchange is indicated for acute postoperative periprosthetic joint infections (typically within 4 weeks of surgery) with well-fixed implants. This approach minimizes morbidity while effectively eradicating early biofilm.

Question 4484

Topic: 3. Adult Reconstruction (Hip & Knee)

A 42-year-old male with a ceramic-on-ceramic THA complains of a reproducible squeaking noise during deep hip flexion and walking. Radiographs are unremarkable. Which of the following is the most common underlying cause of this phenomenon?

. Subclinical periprosthetic joint infection
. Edge loading due to component malposition
. Catastrophic ceramic head fracture
. Metallosis from modular taper wear
. Aseptic loosening of the femoral stem

Correct Answer & Explanation

. Edge loading due to component malposition

Explanation

Squeaking in ceramic-on-ceramic THA is most commonly associated with edge loading caused by component malposition, such as excessive cup anteversion, steep inclination, or loss of fluid film lubrication (stripe wear).

Question 4485

Topic: Total Hip Arthroplasty (THA)

During a primary THA, the surgeon inadvertently decreases the patient's femoral offset by 10 mm. Which of the following is the most likely clinical consequence of this technical error?

. Decreased joint reactive forces across the hip
. Increased risk of postoperative dislocation and a Trendelenburg gait
. Increased mechanical advantage of the abductor musculature
. Significant leg length discrepancy with a lengthened operative leg
. Reduced volumetric wear of the polyethylene liner

Correct Answer & Explanation

. Increased risk of postoperative dislocation and a Trendelenburg gait

Explanation

Decreasing femoral offset reduces the moment arm of the abductor muscles, leading to weakness and a Trendelenburg gait. It also decreases soft tissue tension, thereby significantly increasing the risk of instability and postoperative dislocation.

Question 4486

Topic: Total Hip Arthroplasty (THA)

A 55-year-old female presents with persistent anterior groin pain 1 year post-THA. Pain is elicited with an active straight leg raise. Cross-sectional imaging reveals the acetabular component overhangs the anterior bone edge by 12 mm. What is the most appropriate definitive management?

. Arthroscopic iliopsoas tenotomy
. Open iliopsoas tenotomy
. Revision of the acetabular component
. Revision of the femoral component
. Ultrasound-guided corticosteroid injection into the psoas sheath

Correct Answer & Explanation

. Revision of the acetabular component

Explanation

While iliopsoas impingement is often treated with tenotomy, significant anterior cup overhang (generally >8 mm) provides a mechanical block that will cause tenotomy to fail. Acetabular component revision is the definitive treatment in this scenario.

Question 4487

Topic: 3. Adult Reconstruction (Hip & Knee)
What is the primary advantage of utilizing highly cross-linked polyethylene (HXLPE) compared to conventional ultra-high-molecular-weight polyethylene (UHMWPE) in total hip arthroplasty?
. Increased fracture toughness and yield strength
. Decreased volumetric wear and subsequent osteolysis
. Total resistance to in vivo oxidation
. Elimination of the risk of component impingement
. Improved fatigue strength

Correct Answer & Explanation

. Decreased volumetric wear and subsequent osteolysis

Explanation

The cross-linking process significantly reduces volumetric wear, minimizing the generation of wear debris and macrophage-mediated osteolysis. However, this process comes at the cost of reduced fracture toughness and fatigue strength.

Question 4488

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old male with a history of external beam pelvic irradiation for prostate cancer requires a THA for secondary hip osteoarthritis. What is the most significant concern regarding implant fixation in this patient?

. High failure rate of cemented femoral stems
. High failure rate of standard cementless acetabular components
. Inability to use highly cross-linked polyethylene
. Absolute contraindication to dual-mobility articulations
. Increased risk of catastrophic ceramic head fracture

Correct Answer & Explanation

. High failure rate of standard cementless acetabular components

Explanation

Pelvic radiation impairs local osteoblast function and vascularity, leading to high rates of aseptic loosening in standard cementless acetabular cups due to poor biological ingrowth. A cemented cup with a cage or a highly porous trabecular metal construct is preferred.

Question 4489

Topic: 3. Adult Reconstruction (Hip & Knee)
A 72-year-old male underwent a total knee arthroplasty 18 months ago. He now presents with persistent dull knee pain, stiffness, and occasional warmth. Erythrocyte Sedimentation Rate (ESR) is 45 mm/hr (normal <20), C-reactive protein (CRP) is 30 mg/L (normal <5). Aspiration reveals synovial fluid white blood cell (WBC) count of 3,500 cells/ยตL with 75% neutrophils. Gram stain is negative. What is the most likely diagnosis based on these findings, according to MSIS criteria?
. Aseptic loosening.
. Acute periprosthetic joint infection.
. Chronic periprosthetic joint infection.
. Gouty arthritis.
. Tendinopathy.

Correct Answer & Explanation

. Chronic periprosthetic joint infection.

Explanation

This scenario strongly suggests chronic periprosthetic joint infection (PJI). According to the Musculoskeletal Infection Society (MSIS) criteria for total knee arthroplasty, a synovial fluid WBC count greater than 3,000 cells/ยตL and a polymorphonuclear neutrophil (PMN) percentage greater than 70% are major criteria for PJI. The elevated ESR and CRP further support the diagnosis. While a Gram stain is negative, it has low sensitivity for PJI. Given the presentation 18 months post-op, it is chronic. Acute PJI (Option B) usually presents within 3 months of surgery. Aseptic loosening (Option A) would typically not present with such elevated inflammatory markers or synovial fluid findings. Gouty arthritis (Option D) would have characteristic crystals in the synovial fluid and typically a more acute, inflammatory presentation. Tendinopathy (Option E) would not cause these systemic and synovial fluid changes.

Question 4490

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old female undergoes a posterior approach total hip arthroplasty for osteoarthritis. She experiences two dislocations within the first 6 weeks post-operatively, both with similar mechanisms (hip flexion, adduction, internal rotation). Radiographs confirm satisfactory component position. She is otherwise healthy. What is the most appropriate next step in management?

. Continue with closed reduction and hip precautions.
. Perform an open reduction and capsular repair.
. Convert to a dual mobility total hip arthroplasty.
. Prescribe an abduction brace and intensive physical therapy.
. Consider a Girdlestone resection arthroplasty.

Correct Answer & Explanation

. Convert to a dual mobility total hip arthroplasty.

Explanation

Recurrent instability after total hip arthroplasty (THA) with appropriately positioned components (as stated in the question) is a challenging problem. While hip precautions and an abduction brace (Option D) are part of initial management, two dislocations within 6 weeks suggest an inherent instability issue, often related to soft tissue laxity or insufficient head-to-neck ratio in standard components. In such cases, surgical revision is usually indicated. Converting to a dual mobility total hip arthroplasty (Option C) is an excellent option for recurrent instability, as it significantly increases the jump distance and stability by incorporating two articulating surfaces (a small femoral head within a polyethylene liner, which then articulates with a larger outer polyethylene liner fixed in the acetabular shell). Open reduction and capsular repair (Option B) might be considered for isolated soft tissue issues but is less effective for recurrent dislocations. Continuing with closed reduction (Option A) is not a long-term solution. Girdlestone resection arthroplasty (Option E) is a salvage procedure for intractable infection or failed multiple revisions, not typically for isolated instability with otherwise well-functioning components.

Question 4491

Topic: 3. Adult Reconstruction (Hip & Knee)
During preoperative planning for a total hip arthroplasty, a templated acetabular component shows 65% coverage of the host bone. The surgeon notes significant anterior and posterior column deficiencies. The patient is a 70-year-old female with severe osteoarthritis and normal bone quality otherwise. What is the most appropriate strategy to achieve adequate coverage and stability?
. Use an uncemented hemispherical cup and accept the less than ideal coverage.
. Utilize a larger diameter hemispherical cup to improve coverage.
. Employ an oblong or extended-flange acetabular component.
. Cement a standard polyethylene liner into the remaining bone.
. Opt for a custom triflange acetabular component.

Correct Answer & Explanation

. Employ an oblong or extended-flange acetabular component.

Explanation

Achieving adequate host bone coverage for an uncemented acetabular component is critical for primary stability and long-term osseointegration. A coverage of 65% is generally considered inadequate (aim for >70-80%). When there are significant column deficiencies leading to this problem, a standard hemispherical cup (Options 0, 1) may not be sufficient. A larger diameter hemispherical cup (Option 1) will not necessarily solve the problem if the deficiency is in a specific area (anterior/posterior columns). In such cases, an oblong or extended-flange acetabular component (Option 2) is designed to provide better purchase and coverage over the deficient areas of the acetabulum, enhancing stability and potential for ingrowth. Cementing a standard polyethylene liner (Option 3) is not ideal for long-term stability in a deficient acetabulum. A custom triflange acetabular component (Option 4) is a highly specialized and expensive option typically reserved for severe bone loss (e.g., Paprosky Type III or IV defects) or failed revisions where standard components are insufficient.

Question 4492

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old male presents with persistent right total knee arthroplasty (TKA) pain for 6 months. His inflammatory markers are mildly elevated (ESR 45 mm/hr, CRP 25 mg/L). Knee aspiration yields 3 mL of synovial fluid with a leukocyte count of 3,500 cells/ยตL and 72% polymorphonuclear leukocytes (PMNs). Gram stain is negative. Cultures remain negative after 5 days. What is the MOST appropriate next step in management?

. Initiate empiric intravenous antibiotics and observe.
. Proceed with a single-stage revision TKA.
. Obtain a synovial fluid alpha-defensin test and send for extended cultures.
. Perform an arthroscopy with debridement and exchange of modular components.
. Advise physical therapy and pain management, considering non-infectious causes.

Correct Answer & Explanation

. Obtain a synovial fluid alpha-defensin test and send for extended cultures.

Explanation

This patient presents with a 'culture-negative' periprosthetic joint infection (PJI), which is a significant diagnostic challenge. The aspiration fluid analysis (leukocyte count >2000 cells/ยตL and PMN >65% in a TKA, along with elevated inflammatory markers) is highly suggestive of infection, despite negative routine cultures.Option A (Empiric IV antibiotics) is premature without definitive diagnosis and may suppress subsequent cultures.Option B (Single-stage revision) is generally not recommended for culture-negative PJI without a confirmed organism, especially if the diagnosis is still somewhat uncertain.Option C (Synovial fluid alpha-defensin test and extended cultures) is the most appropriate next step. Alpha-defensin is a highly sensitive and specific biomarker for PJI, especially valuable in culture-negative cases. Sending for extended cultures (up to 14 days, with specific media for fastidious organisms) increases the yield of identifying elusive pathogens. This approach aims to confirm the diagnosis and identify the causative organism before proceeding with definitive surgical treatment.Option D (Arthroscopy with debridement) is typically considered for acute PJI or for chronic PJI with retained components (e.g., DAIR - Debridement, Antibiotics, and Implant Retention), but it is a surgical intervention that might be insufficient for chronic infection and should be guided by a definitive diagnosis.Option E (Physical therapy and pain management) would ignore strong indicators of infection and risk progression of the PJI.

Question 4493

Topic: 3. Adult Reconstruction (Hip & Knee)

A 60-year-old male undergoes a revision total hip arthroplasty (THA) for recurrent aseptic loosening of the acetabular component. Intraoperatively, extensive lysis and thinning of the anterior and posterior acetabular walls are noted, making secure screw fixation challenging. What is the MOST appropriate reconstruction technique for acetabular deficiency in this scenario?

. Impaction bone grafting with a standard cementless cup.
. Reinforcement ring or cage with bone graft and cemented liner.
. Placement of a standard cementless cup with supplemental screws.
. Use of a jumbo cup for press-fit fixation.
. Polymethylmethacrylate (PMMA) cement only.

Correct Answer & Explanation

. Reinforcement ring or cage with bone graft and cemented liner.

Explanation

This scenario describes a complex acetabular revision due to significant bone loss (lysis and thinning of walls), which is a common challenge in revision THA. The key is to reconstruct the bone deficiency and provide stable fixation for the new component.Option A (Impaction bone grafting with a standard cementless cup) is an excellent technique for acetabular contained defects or segmental defects where there is a deficient rim. This involves compacting morselized cancellous bone graft into the defect to reconstruct the bone stock, followed by the insertion of a standard cementless cup. This approach allows for biological incorporation of the graft and restores long-term bone stock. While it's typically used for contained defects, it can be part of the solution for extensive lysis creating wall deficiencies.Option B (Reinforcement ring or cage with bone graft and cemented liner) is the MOST appropriate reconstruction technique for significant acetabular bone loss, particularly when there are uncontained defects or loss of columns/walls, making primary fixation of a cementless cup difficult or impossible. These devices provide mechanical stability (bypassing the deficient bone) and create a contained space for bone graft, promoting biological ingrowth or allowing for cemented liner fixation. The description of 'extensive lysis and thinning of the anterior and posterior acetabular walls' suggests a defect that might be uncontained or too large for just a standard cup or impaction grafting alone without additional structural support.Option C (Placement of a standard cementless cup with supplemental screws) is often sufficient for minor contained defects but is inadequate for extensive wall thinning and lysis, as screws would have poor purchase.Option D (Use of a jumbo cup) might provide better press-fit in some cases, but it doesn't address significant bone loss and may not be stable if the walls are extensively thinned. It can also lead to impingement issues.Option E (PMMA cement only) without a structural component is only used for certain contained defects and is not a reconstructive technique for significant bone loss, and the longevity is often poor without underlying bone support.

Question 4494

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old male undergoes a two-stage revision total knee arthroplasty for a chronic periprosthetic joint infection (PJI) caused by Pseudomonas aeruginosa. Following explantation and antibiotic spacer placement, he receives 6 weeks of intravenous meropenem. At the time of reimplantation, all aspirates are negative, and inflammatory markers have normalized. What specific cement formulation should be utilized for the new prosthesis to minimize recurrence, given the known challenges with Gram-negative organisms?

. High-dose vancomycin-impregnated cement.
. Cement with gentamicin and clindamycin.
. Cement with gentamicin and tobramycin.
. Cement with daptomycin and vancomycin.
. Cement with gentamicin and ceftazidime.

Correct Answer & Explanation

. Cement with gentamicin and tobramycin.

Explanation

For periprosthetic joint infections (PJI) caused by Gram-negative organisms likePseudomonas aeruginosa, the choice of antibiotic-impregnated cement is crucial. Aminoglycosides (gentamicin, tobramycin) are highly effective against Gram-negative bacteria and are heat-stable, making them suitable for mixing with bone cement. Therefore, using cement impregnated with two aminoglycosides, such as gentamicin and tobramycin, provides a robust local antibiotic delivery system against Gram-negative pathogens. Options A, B, and D are less ideal because vancomycin (Gram-positive coverage) and clindamycin (Gram-positive and some anaerobes) are not primary agents forPseudomonas. While ceftazidime (Option E) has Gram-negative coverage, aminoglycosides offer a more established and synergistic approach in cement forPseudomonas.

Question 4495

Topic: 3. Adult Reconstruction (Hip & Knee)

A 58-year-old male who underwent a metal-on-metal (MoM) total hip arthroplasty 8 years ago presents with new onset groin pain, pseudo-tumor formation, and elevated serum cobalt and chromium levels (Cobalt: 15 ยตg/L, Chromium: 20 ยตg/L). He is otherwise healthy. What is the most significant long-term systemic risk associated with these findings?

. Development of peripheral neuropathy.
. Increased risk of deep venous thrombosis.
. Cardiomyopathy and thyroid dysfunction.
. Osteolysis and aseptic loosening.
. Hepatic dysfunction and renal failure.

Correct Answer & Explanation

. Cardiomyopathy and thyroid dysfunction.

Explanation

Elevated serum cobalt and chromium levels from metal-on-metal (MoM) hip arthroplasty are associated with various systemic toxicities. The most significant long-term systemic risks include cardiomyopathy (leading to heart failure) and thyroid dysfunction (hypothyroidism), as well as neurological effects like peripheral neuropathy, visual impairment, and hearing loss. Renal impairment has also been reported. While osteolysis and aseptic loosening (Option D) are local complications, the question asks aboutsystemicrisks. Peripheral neuropathy (Option A) is a systemic risk, but cardiomyopathy and thyroid dysfunction are often highlighted as particularly serious and well-documented complications. The combination in Option C represents the most significant and well-studied systemic risks. Deep venous thrombosis (Option B) is not a direct consequence of metal ion toxicity. Hepatic dysfunction and renal failure (Option E) can occur, but cardiomyopathy and thyroid dysfunction are more consistently reported and significant concerns in the context of MoM hip arthroplasty metal ion toxicity.

Question 4496

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old male with a history of chronic alcoholism and osteopenia presents with acute onset of severe left hip pain after a ground-level fall. X-rays show a displaced femoral neck fracture. He is hemodynamically stable. Which of the following factors would MOST strongly influence the decision towards a hemiarthroplasty rather than internal fixation (e.g., cannulated screws)?

. The patient's age and high activity level prior to injury.
. The fracture classification being Garden Type II or Pauwels Type II.
. Significant comminution of the femoral head or neck, precluding stable fixation.
. The patient's current smoking status.
. A short surgical wait time and availability of operating room.

Correct Answer & Explanation

. Significant comminution of the femoral head or neck, precluding stable fixation.

Explanation

In elderly patients, displaced femoral neck fractures carry a high risk of avascular necrosis and nonunion after internal fixation. While age and activity level (Option A) are general considerations, 'high activity level' would typically favor a total hip arthroplasty over hemiarthroplasty or fixation. Garden Type II or Pauwels Type II (Option B) fractures are typically stable or undisplaced, favoring internal fixation, not hemiarthroplasty. Smoking status (Option D) is a general risk factor for poor healing but doesn't specifically contraindicate fixation over arthroplasty more than significant comminution. Surgical wait time (Option E) is a logistical factor, not a clinical indication. Significant comminution of the femoral head or neck (Option C) can make internal fixation unstable and prone to failure, thereby strongly favoring arthroplasty (hemi or total, depending on patient factors) as a more reliable solution in a displaced femoral neck fracture in an elderly patient. This scenario specifically asks what would 'most strongly influence the decision towards a hemiarthroplasty,' implying a situation where fixation is highly unlikely to succeed.

Question 4497

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old female presents with severe, chronic left knee pain due to osteoarthritis. She underwent a left total knee arthroplasty (TKA) 5 years ago, which provided good relief. For the past 6 months, she has experienced increasing pain, particularly with weight-bearing and at night. Radiographs show well-fixed components without signs of loosening. Synovial fluid aspiration reveals a white blood cell count of 1800 cells/ยตL with 75% neutrophils, and a positive alpha-defensin test. What is the most appropriate next step in management?

. Trial of non-steroidal anti-inflammatory drugs (NSAIDs) and physical therapy.
. Arthroscopic debridement and irrigation with retention of components.
. Two-stage revision arthroplasty with an interim antibiotic spacer.
. One-stage revision arthroplasty with antibiotic-loaded cement.
. Referral for pain management injections.

Correct Answer & Explanation

. Two-stage revision arthroplasty with an interim antibiotic spacer.

Explanation

The patient's symptoms (chronic increasing pain, night pain), synovial fluid analysis (WBC 1800 cells/ยตL with 75% PMN), and a positive alpha-defensin test are highly indicative of a chronic prosthetic joint infection (PJI). The alpha-defensin test has high sensitivity and specificity for PJI. Given the chronicity of symptoms (6 months) and the high probability of infection, a two-stage revision arthroplasty (Option C) is generally considered the gold standard for chronic PJI. This involves explantation of components, thorough debridement, placement of an antibiotic spacer, and then reimplantation after infection eradication is confirmed. NSAIDs and physical therapy (Option A) are inappropriate for PJI. Arthroscopic debridement and irrigation with retention of components (DAIR) (Option B) is primarily reserved for acute PJI (<3-4 weeks from symptom onset or surgical event) and has a high failure rate in chronic cases. One-stage revision (Option D) can be considered in highly selected cases with susceptible organisms and good soft tissues, but two-stage remains the most reliable for chronic PJI. Pain management injections (Option E) do not address the underlying infection.

Question 4498

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following statements best describes the primary biological function of a high-density, porous-coated implant surface in total joint arthroplasty?

. To increase the surface area for antibiotic elution.
. To promote osteointegration through bone ingrowth into the pores.
. To reduce friction and wear between articulating surfaces.
. To provide immediate mechanical interlocking for primary stability.
. To enhance electrical conductivity for bone stimulation.

Correct Answer & Explanation

. To promote osteointegration through bone ingrowth into the pores.

Explanation

High-density, porous-coated implant surfaces are designed to promote biological fixation, primarily through osteointegration, which is the direct structural and functional connection between ordered, living bone and the surface of a load-carrying implant. This occurs via bone ingrowth into the pores of the coating (Option B). Option A is incorrect; while some coatings can be infused with antibiotics, this is not the primary biological function of a porous coating itself. Option C relates to the articulating surfaces (e.g., polyethylene against metal), not the implant-bone interface. Option D, immediate mechanical interlocking, refers more to press-fit stability achieved at the time of implantation, which is a prerequisite for successful ingrowth but not the biological function of the porous coating itself. Option E is incorrect, as these coatings do not primarily enhance electrical conductivity for bone stimulation.

Question 4499

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year-old female presents with severe pain and functional impairment due to advanced osteoarthritis of the carpometacarpal (CMC) joint of the thumb. She has failed multiple courses of conservative treatment including splinting, NSAIDs, and corticosteroid injections. Radiographs show Grade IV trapezial-metacarpal arthritis with subluxation. What is the most appropriate surgical option?

. Trapezial-metacarpal arthrodesis.
. Excision arthroplasty (trapeziectomy) alone.
. Ligament reconstruction tendon interposition (LRTI) arthroplasty.
. Resection arthroplasty of the trapezium with Silastic implant.
. CMC joint denervation.

Correct Answer & Explanation

. Ligament reconstruction tendon interposition (LRTI) arthroplasty.

Explanation

For advanced, symptomatic CMC joint arthritis that has failed conservative management, surgical intervention is indicated. Trapezial-metacarpal arthrodesis (Option A) provides pain relief and stability but at the expense of motion, making it less ideal for a 70-year-old patient who needs good thumb mobility for daily activities. Excision arthroplasty (trapeziectomy) alone (Option B) involves removing the trapezium, which provides pain relief by eliminating the arthritic joint. It is a well-established and often sufficient procedure, especially in less demanding patients. Ligament reconstruction tendon interposition (LRTI) arthroplasty (Option C) builds upon trapeziectomy by using a tendon (e.g., FCR) to reconstruct the ligament and fill the void, aiming for better stability and strength, but it is a more extensive procedure. For Grade IV arthritis in an elderly patient, LRTI is often considered the gold standard as it offers the best balance of pain relief and functional outcomes with minimal complications. Resection arthroplasty with Silastic implant (Option D) is largely historical due to implant-related complications. Denervation (Option E) is a pain-modulating procedure but does not address the underlying joint mechanics or deformity. Given the advanced nature of the arthritis and patient age, LRTI (Option C) offers a superior functional outcome compared to trapeziectomy alone for many patients, hence it is chosen over B, which is still a valid option but often combined with LRTI. If the patient's demands are very low, trapeziectomy alone could be sufficient. However, LRTI is often preferred for more robust function. Re-evaluating the options, LRTI (Option C) is generally considered superior to trapeziectomy alone for Grade IV arthritis for better stability and longevity, though trapeziectomy alone is also effective. The question asks for the 'most appropriate surgical option', and LRTI is often favored for robust outcomes in advanced cases.

Question 4500

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following is the most critical factor in determining the risk of avascular necrosis (AVN) following a displaced femoral neck fracture in an adult?

. The patient's age and bone mineral density.
. The degree of comminution of the femoral neck.
. The time from injury to definitive surgical intervention.
. The extent of disruption to the retinacular blood supply to the femoral head.
. The patient's co-morbidities such as diabetes or smoking.

Correct Answer & Explanation

. The extent of disruption to the retinacular blood supply to the femoral head.

Explanation

The most critical factor influencing the risk of avascular necrosis (AVN) of the femoral head following a displaced femoral neck fracture is the extent of disruption to the retinacular blood supply (specifically the lateral epiphyseal vessels) to the femoral head (Option D). Displaced femoral neck fractures often tear these vessels, which are the primary blood supply to the femoral head, leading to ischemia and subsequent AVN. While patient age (Option A), comminution (Option B), time to surgery (Option C), and co-morbidities (Option E) are all important factors influencing prognosis, the direct damage to the blood supply is the fundamental underlying cause of AVN. The quality of reduction and stability of fixation subsequently impact the likelihood of revascularization and healing, but the initial vascular insult is paramount.

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