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 3421
Topic: 3. Adult Reconstruction (Hip & Knee)
A 30-year-old man sustains a displaced, vertically oriented (Pauwels Type III) femoral neck fracture. What is the most appropriate surgical management to minimize the risk of nonunion and avascular necrosis?
Correct Answer & Explanation
. Closed reduction and percutaneous in situ pinning
Explanation
Young patients with displaced femoral neck fractures require urgent anatomic reduction and stable internal fixation. A sliding hip screw (with or without a derotational screw) or length-stable construct is biomechanically superior to parallel screws for vertically oriented (Pauwels III) fractures.
Question 3422
Topic: 3. Adult Reconstruction (Hip & Knee)
A 78-year-old female falls from a standing height and sustains an anterior column/posterior hemitransverse acetabular fracture. Radiographs and CT imaging show severe osteopenia, marginal impaction of the superior dome, and full-thickness cartilage damage to the femoral head (gull sign). What is the most appropriate definitive management?
Correct Answer & Explanation
. Conservative management with restricted weight-bearing
Explanation
In elderly patients with specific acetabular fractures complicated by severe impaction (gull sign), severe osteopenia, or femoral head damage, combining limited ORIF (to stabilize the columns) with acute THA yields superior functional outcomes compared to ORIF alone.
Question 3423
Topic: 3. Adult Reconstruction (Hip & Knee)
A 70-year-old male with a history of a cemented total hip arthroplasty (THA) sustains a spiral fracture of the femoral diaphysis after a minor fall. The fracture occurs entirely distal to the tip of the well-fixed femoral stem (Vancouver C). What is the recommended surgical management?
Correct Answer & Explanation
. Revision to a long-stem, extensively porous-coated implant
Explanation
Vancouver C periprosthetic fractures occur well below the tip of the prosthesis. They are managed similarly to standard diaphyseal femur fractures but require internal fixation with a plate that safely overlaps the distal tip of the existing stem to prevent a stress riser.
Question 3424
Topic: 3. Adult Reconstruction (Hip & Knee)
A 40-year-old female with chronic axial low back pain undergoes an MRI without contrast. The T1-weighted images show hypointense signal at the L4-L5 vertebral endplates, while the T2-weighted images show hyperintense signal in the same areas. These Modic Type 1 changes histologically represent which of the following?
Correct Answer & Explanation
. Fatty replacement of the bone marrow
Explanation
Modic Type 1 changes (T1 hypointense, T2 hyperintense) represent bone marrow edema and fibrovascular tissue replacement. These changes are highly correlated with active discogenic low back pain and segmental instability.
Question 3425
Topic: 3. Adult Reconstruction (Hip & Knee)
Which of the following is considered an absolute contraindication to a total ankle arthroplasty in a patient with end-stage post-traumatic ankle osteoarthritis?
Correct Answer & Explanation
. Age greater than 70 years
Explanation
Extensive avascular necrosis (>50% of the talar body) is an absolute contraindication to total ankle arthroplasty. The lack of structural support for the talar component leads to early subsidence and catastrophic implant failure.
Question 3426
Topic: 3. Adult Reconstruction (Hip & Knee)
When evaluating a patient with end-stage ankle osteoarthritis for surgical intervention, which of the following is considered an absolute contraindication for total ankle arthroplasty (TAA)?
Correct Answer & Explanation
. Patient age greater than 65 years
Explanation
Significant avascular necrosis (>50%) of the talar body is an absolute contraindication to total ankle arthroplasty because a viable bone bed is required for component support and ingrowth. Other absolute contraindications include active infection, Charcot arthropathy, and absent leg sensation.
Question 3427
Topic: 3. Adult Reconstruction (Hip & Knee)
A 62-year-old man with end-stage post-traumatic ankle osteoarthritis presents for surgical consultation. He has a BMI of 28, is a non-smoker, and has well-controlled hypertension. Examination reveals severe tibiotalar arthritis but an intact and perfectly aligned hindfoot. His ankle range of motion is 5 degrees of dorsiflexion to 20 degrees of plantarflexion. Which of the following would be considered an absolute contraindication to a total ankle arthroplasty (TAA) in this patient?
Correct Answer & Explanation
. A history of prior medial malleolus fracture
Explanation
Significant avascular necrosis (typically >50%) of the talar body is an absolute contraindication to total ankle arthroplasty (TAA) due to inadequate bone stock, which leads to a very high risk of talar component subsidence and failure. Other absolute contraindications include active infection, severe peripheral neuropathy (e.g., Charcot arthropathy), and absent or non-functioning leg musculature. Age <65 and mild coronal deformities are relative, not absolute, contraindications.
Question 3428
Topic: 3. Adult Reconstruction (Hip & Knee)
A 68-year-old man with severe post-traumatic osteoarthritis of the right ankle is being evaluated for surgical intervention. He reports significant pain with weight-bearing activities. His past medical history is significant for well-controlled type 2 diabetes mellitus, hypertension, active Charcot neuroarthropathy of the midfoot, and a remote history of a deep vein thrombosis. Radiographs show bone-on-bone tibiotalar arthritis with 5 degrees of coronal plane varus deformity. Which of the following is an ABSOLUTE contraindication to performing a total ankle arthroplasty (TAA) in this patient?
Correct Answer & Explanation
. His age of 68 years.
Explanation
Total ankle arthroplasty (TAA) is a viable option for end-stage ankle arthritis, but strict patient selection is crucial for success. Absolute contraindications for TAA include active infection, severe peripheral neuropathy, absent plantar sensation, active or prior Charcot neuroarthropathy, avascular necrosis involving more than 50% of the talar body, and severe uncorrectable malalignment. Age over 65 is generally considered a good indication due to lower functional demands compared to younger patients. Mild coronal malalignment (up to 10-15 degrees) can usually be corrected with concurrent soft tissue balancing or osteotomies. Well-controlled diabetes is a relative risk factor but not an absolute contraindication.
Question 3429
Topic: 3. Adult Reconstruction (Hip & Knee)
A 65-year-old female presents with chronic pain and stiffness in her right thumb. She reports difficulty with pinch activities and opening jars. Examination reveals squaring of the carpometacarpal (CMC) joint of the thumb, a positive grind test, and tenderness at the base of the thumb. Radiographs confirm severe osteoarthritis of the first CMC joint (Eaton Stage IV). She has failed activity modification, NSAIDs, and corticosteroid injections. What is the MOST appropriate surgical intervention?
Correct Answer & Explanation
. CMC joint fusion
Explanation
The patient has symptomatic, end-stage osteoarthritis of the first carpometacarpal (CMC) joint, refractory to conservative treatment. Trapeziectomy with ligament reconstruction and tendon interposition (LRTI) is considered the gold standard surgical treatment for severe thumb CMC osteoarthritis. This procedure involves removing the arthritic trapezium bone, which eliminates the painful joint, and then reconstructing the volar oblique ligament and interposing a local tendon graft (e.g., FCR) to maintain space and prevent proximal migration of the first metacarpal. CMC joint fusion provides excellent pain relief but sacrifices motion, which can be limiting, especially for bilateral cases or those requiring fine dexterity. CMC joint replacement arthroplasty is an option, but LRTI has a long track record of success. Arthrodesis of the IP joint is for IP joint arthritis. Proximal row carpectomy is for carpal arthritis.
Question 3430
Topic: 3. Adult Reconstruction (Hip & Knee)
A 68-year-old male presents with a fixed flexion deformity of his ring finger PIP joint following a crush injury 6 months ago. He has undergone extensive hand therapy, but the contracture remains at 60 degrees. Passive extension is limited. Radiographs show no significant joint destruction. What is the MOST appropriate surgical intervention?
Correct Answer & Explanation
. Flexor tenolysis
Explanation
A fixed flexion deformity of the PIP joint following trauma, refractory to therapy, with limited passive extension and no significant joint destruction, points to a joint contracture primarily involving the capsule and collateral ligaments. A capsulectomy (excision of contracted joint capsule, often combined with release of collateral ligaments and volar plate) is the most appropriate procedure to restore passive range of motion. Flexor tenolysis would be for extrinsic flexor tendon adhesions, but passive motion is limited, suggesting joint contracture. Extensor tenolysis is rarely indicated for flexion contractures. Arthrodesis or arthroplasty are salvage procedures for severe joint destruction or failed contracture release, not indicated if the joint itself is relatively preserved. Early intervention with capsulectomy offers the best chance to restore motion.
Question 3431
Topic: 3. Adult Reconstruction (Hip & Knee)
A 68-year-old female undergoes ORIF for a displaced three-part proximal humerus fracture. One week post-operatively, she complains of increasing pain, swelling, and purulent discharge from the incision site, along with fever. She has limited range of motion and systemic signs of infection. What is the MOST appropriate immediate management?
Correct Answer & Explanation
. Oral antibiotics and wound care
Explanation
The patient presents with clear signs of an acute deep periprosthetic joint infection (PJI) following ORIF of a proximal humerus fracture: increasing pain, swelling, purulent discharge, fever, limited ROM, and systemic signs. This is a surgical emergency. The MOST appropriate immediate management is urgent surgical debridement and irrigation of the surgical site, thorough tissue sampling for cultures and sensitivity, and initiation of empiric intravenous antibiotics. Oral antibiotics and wound care alone are insufficient for deep infection. Aspiration may provide a diagnosis, but surgical debridement is therapeutic and critical for source control. Removal of fixation may be necessary for chronic infection, but initially, preservation of hardware is attempted if stable, while aggressive debridement is performed. Observation is inappropriate.
Question 3432
Topic: 3. Adult Reconstruction (Hip & Knee)
In the setting of a primary linked semi-constrained total elbow arthroplasty (TEA) performed for rheumatoid arthritis, which of the following is the most common long-term complication?
Correct Answer & Explanation
. Ulnar neuropathy
Explanation
The most common long-term complication of total elbow arthroplasty, particularly in linked semi-constrained designs, is aseptic loosening. While ulnar neuropathy, infection, triceps insufficiency, and periprosthetic fractures are important complications, aseptic loosening has the highest incidence over time due to the high mechanical stresses across the implant interfaces. Bushing wear can also contribute to osteolysis and subsequent aseptic loosening.
Question 3433
Topic: 3. Adult Reconstruction (Hip & Knee)
A 60-year-old patient undergoes total knee arthroplasty. Which type of wear mechanism is typically most concerning for long-term polyethylene liner failure due to microscopic particle release leading to osteolysis?
Correct Answer & Explanation
. Adhesive wear
Explanation
Fatigue wear is generally the most concerning type of wear in total joint arthroplasty polyethylene liners. It involves the propagation of subsurface cracks under cyclic loading, leading to the release of microscopic polyethylene particles. These particles initiate an inflammatory response, leading to osteolysis and aseptic loosening. Adhesive and abrasive wear are also relevant but less often the primary mode of catastrophic failure. Third-body wear involves particles from other sources. Corrosion wear is typically metallic.
Question 3434
Topic: Total Hip Arthroplasty (THA)
Which of the following describes the 'stress-shielding' phenomenon observed in orthopedic implants?
Correct Answer & Explanation
. Increased stress on the bone due to excessive implant rigidity.
Explanation
Stress-shielding refers to the phenomenon where a stiff orthopedic implant (e.g., a total hip stem) bears a significant portion of the mechanical load, thereby 'shielding' the adjacent bone from its normal physiological stress. In accordance with Wolff's Law, this reduction in stress leads to bone resorption and decreased bone density in the shielded areas, which can potentially lead to implant loosening or periprosthetic fracture risk.
Question 3435
Topic: 3. Adult Reconstruction (Hip & Knee)
Which of the following imaging modalities is considered the 'gold standard' for diagnosing early avascular necrosis (AVN) of the femoral head?
Correct Answer & Explanation
. Plain Radiographs (X-rays)
Explanation
Magnetic Resonance Imaging (MRI) is the 'gold standard' for diagnosing early avascular necrosis (AVN) of the femoral head. It can detect changes in bone marrow edema and fat necrosis before any radiographic changes are visible. Plain radiographs are typically normal in early AVN. CT scans are good for bony detail but less sensitive than MRI for early marrow changes. Bone scintigraphy can be sensitive but less specific than MRI.
Question 3436
Topic: 3. Adult Reconstruction (Hip & Knee)
A 65-year-old patient presents with aseptic loosening 15 years following a total hip arthroplasty. Radiographs reveal extensive eccentric osteolysis. The primary biological mediator of this osteolysis is activated by which of the following mechanisms?
Correct Answer & Explanation
. Direct mechanical abrasion of the subchondral bone by the metallic stem over time
Explanation
The primary cause of long-term aseptic loosening in joint arthroplasty is wear debris-induced osteolysis. UHMWPE particles (typically between 0.1 and 1.0 micrometers in size) are phagocytosed by macrophages. The macrophages become activated and release pro-inflammatory cytokines (such as TNF-alpha, IL-1, and IL-6), which subsequently stimulate osteoclastogenesis via the RANKL pathway, leading to localized bone resorption.
Question 3437
Topic: 3. Adult Reconstruction (Hip & Knee)
A 60-year-old patient undergoes a total knee arthroplasty. The articular cartilage removed during surgery naturally functions to minimize friction, primarily through boundary lubrication at high loads. Which molecule is most responsible for this boundary lubrication in a healthy joint?
Correct Answer & Explanation
. Hyaluronic acid
Explanation
Lubricin (proteoglycan 4 or PRG4) is a glycoprotein synthesized by superficial zone chondrocytes and synoviocytes. It is the primary molecule responsible for boundary lubrication in articular cartilage, significantly reducing friction during high-load, low-velocity joint movement. Hyaluronic acid contributes primarily to elastohydrodynamic lubrication in synovial fluid.
Question 3438
Topic: 3. Adult Reconstruction (Hip & Knee)
In modern total hip arthroplasty, highly cross-linked polyethylene (HXLPE) is utilized to decrease wear rates. Which of the following is an adverse biomechanical consequence of increasing the radiation dose to maximize cross-linking in the polyethylene manufacturing process?
Correct Answer & Explanation
. Increased adhesive wear
Explanation
While irradiation creates chemical cross-links that significantly improve the wear resistance of polyethylene, it inversely affects certain mechanical properties. Increasing the radiation dose leads to decreased ductility, yield strength, fracture toughness, and ultimate tensile strength, which can increase the risk of mechanical failure or catastrophic cracking of the liner.
Question 3439
Topic: 3. Adult Reconstruction (Hip & Knee)
Highly cross-linked polyethylene (HXLPE) has become the standard bearing surface in total hip arthroplasty to minimize wear and osteolysis. Which of the following is a direct mechanical consequence of the irradiation process used to manufacture HXLPE compared to conventional ultra-high-molecular-weight polyethylene (UHMWPE)?
Correct Answer & Explanation
. Increased ultimate tensile strength
Explanation
Irradiation of UHMWPE creates cross-links between polymer chains, which dramatically improves wear resistance. However, this cross-linking process adversely affects the bulk mechanical properties of the material. Specifically, it decreases ultimate tensile strength, ductility, fatigue strength, and fracture toughness. To eliminate the free radicals generated during irradiation (which cause oxidation), the polyethylene is typically melted or annealed, or doped with Vitamin E.
Question 3440
Topic: 3. Adult Reconstruction (Hip & Knee)
During a single-stage revision total knee arthroplasty for a periprosthetic joint infection, thorough debridement is performed to remove the bacterial biofilm. Which of the following stages of biofilm formation is characterized by the initial secretion of a protective extracellular polymeric substance (EPS) and the beginning of irreversible bacterial adherence?
Correct Answer & Explanation
. Reversible attachment
Explanation
Biofilm formation occurs in stages. Stage 1 is Reversible Attachment, where planktonic bacteria adhere weakly to the surface via Van der Waals forces. Stage 2 is Irreversible Attachment, marked by the initial secretion of the extracellular polymeric substance (EPS), making the attachment permanent. Stages 3 and 4 (Maturation) involve thickening of the EPS, quorum sensing, and metabolic slowing. Stage 5 is Dispersion.
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