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 1701
Topic: 3. Adult Reconstruction (Hip & Knee)
During a primary total knee arthroplasty, the surgeon places the trial components and notes that the knee is perfectly balanced in 90 degrees of flexion, but is symmetrically tight in full extension. Which of the following is the most appropriate intraoperative adjustment?
Correct Answer & Explanation
. Upsize the femoral component
Explanation
A knee that is tight in extension but balanced in flexion indicates a tight extension gap with a normal flexion gap. Resecting more distal femur will increase the extension gap without affecting the flexion gap.
Question 1702
Topic: 3. Adult Reconstruction (Hip & Knee)
A 60-year-old male presents with a third episode of posterior dislocation following a primary total hip arthroplasty performed via a posterior approach. Which of the following component positions is the most likely culprit contributing to his recurrent posterior instability?
Correct Answer & Explanation
. Acetabular retroversion
Explanation
Acetabular retroversion decreases the posterior coverage of the femoral head, making the hip highly susceptible to posterior dislocation, especially with flexion and internal rotation.
Question 1703
Topic: 3. Adult Reconstruction (Hip & Knee)
A 68-year-old male is 3 weeks status post primary total knee arthroplasty. He presents with acute onset of severe knee pain, erythema, and a large effusion. Joint aspiration yields synovial fluid with 65,000 WBC/uL and 95% neutrophils. What is the most appropriate surgical management?
Correct Answer & Explanation
. Arthroscopic joint lavage
Explanation
For acute periprosthetic joint infections occurring within 4 weeks of the index arthroplasty, Debridement, Antibiotics, and Implant Retention (DAIR) with exchange of the modular polyethylene component is the gold standard treatment.
Question 1704
Topic: 3. Adult Reconstruction (Hip & Knee)
A 58-year-old female presents with isolated medial compartment osteoarthritis of the knee. She is being considered for a unicompartmental knee arthroplasty (UKA). Which of the following is considered an absolute contraindication for a mobile-bearing UKA?
Correct Answer & Explanation
. Age greater than 55 years
Explanation
Inflammatory arthropathy is an absolute contraindication to unicompartmental knee arthroplasty due to the systemic nature of the disease, which predictably leads to progressive degeneration of the preserved compartments.
Question 1705
Topic: 3. Adult Reconstruction (Hip & Knee)
During a primary total knee arthroplasty, the surgeon notes that the joint is symmetrically tight in full extension but has symmetric laxity in 90 degrees of flexion. Which of the following is the most appropriate intraoperative adjustment?
Correct Answer & Explanation
. Increase the size of the femoral component
Explanation
A knee that is tight in extension but loose in flexion indicates a flexion gap that is larger than the extension gap. Resecting more distal femur increases the extension gap to match the flexion gap without affecting flexion kinematics.
Question 1706
Topic: Total Hip Arthroplasty (THA)
A 55-year-old highly active female underwent a right total hip arthroplasty using a ceramic-on-ceramic bearing 3 years ago. She now complains of a high-pitched squeaking noise during gait, particularly when extending her hip. Which of the following component position factors is most strongly associated with this phenomenon?
Correct Answer & Explanation
. Acetabular cup retroversion
Explanation
Squeaking in ceramic-on-ceramic THA is highly associated with edge loading, which often results from an unacceptably steep acetabular cup (inclination > 55 degrees). Edge loading disrupts the fluid film lubrication, leading to stripe wear and audible squeaking.
Question 1707
Topic: Total Hip Arthroplasty (THA)
A 70-year-old female undergoes a primary total hip arthroplasty via a posterior approach. Intraoperatively, she is noted to dislocate anteriorly with the hip in extension, external rotation, and adduction. What is the most likely cause of this specific instability pattern?
Correct Answer & Explanation
. Inadequate offset of the femoral stem
Explanation
Anterior dislocation of a THA (occurring in extension and external rotation) is classically caused by excessive combined anteversion, most commonly due to excessive anteversion of the acetabular component. Retroverted cups tend to dislocate posteriorly in flexion and internal rotation.
Question 1708
Topic: 3. Adult Reconstruction (Hip & Knee)
A 75-year-old woman who has groin pain states that she had total hip arthroplasty 15 years ago. The radiograph shown in Figure 40 reveals that the left acetabular component is grossly loose. Revision of the acetabular component should include use of a
Correct Answer & Explanation
. constrained acetabular component
Explanation
The patient has an all-poly acetabular component, which is grossly loose and has migrated. Intermediate and long-term results of revision THA’s using a cemented acetabular component have had high failure and re-revision rates. One of the reasons includes sclerotic bone lacking in the trabeculae needed for cement. Threaded cups and bipolar implants have also had unacceptably high failure rates. Published results using non-cemented components have shown they performed much better in the intermediate-term, especially those supplemented with fins, screws or spikes. The cited authors (Petrera and Rubash) preferred a titanium-mesh cup and place two supplemental screws if the cup is unstable (assessed by manipulation intraoperatively).
Question 1709
Topic: 3. Adult Reconstruction (Hip & Knee)
Figures below show the radiographs obtained from a 75-year-old woman who underwent right total hip arthroplasty in 2009. She did well until last month, when a right posterior hip dislocation occurred after she fell from her bed to the floor. Successful closed reduction was performed. She sustained two more posterior dislocations requiring closed reduction under anesthesia. The surgical report from the index arthroplasty notes a 54-mm monoblock acetabular component with a 28-mm inner diameter compression molded polyethylene and a high offset neck cementless stem with a +8-mm length, 28-mm head. What is the best next step?
Correct Answer & Explanation
. Acetabular revision arthroplasty
Explanation
This patient has demonstrated recurrent instability, and her current implants lack the modularity to upsize and improve the head-neck ratio and range to impingement. Given the monoblock acetabular component and a +7-mm neck length, the best option is revision to a large-diameter femoral head or dual-mobility component. Placement of a hip spica cast and resection arthroplasty are unreasonable. Revision to a longer ball length likely would not solve this recurrent instability pattern.
Question 1710
Topic: 3. Adult Reconstruction (Hip & Knee)
A 62-year-old male presents for revision of his total hip arthroplasty (THA). He originally received a ceramic-on-ceramic bearing. During the procedure, the surgeon notes a catastrophic fracture of the ceramic femoral head.
After a thorough synovectomy, which of the following is the most appropriate management regarding the new bearing surface, assuming the acetabular shell and femoral stem are well-fixed?
Correct Answer & Explanation
. Exchange the liner for highly cross-linked polyethylene and implant a new ceramic head with a titanium adapter sleeve.
Explanation
Fracture of a ceramic femoral head requires meticulous removal of all ceramic shards via an extensive synovectomy to prevent severe third-body wear. A cobalt-chromium (CoCr) head should never be used against an old ceramic liner or in an environment where ceramic particles may remain, as the residual ceramic debris will rapidly scratch and destroy the metal head (metallosis). A new ceramic head cannot simply be placed on the existing trunnion, because the trunnion is often microscopically damaged by the fractured head; placing a new ceramic head directly on a damaged trunnion risks stress risers and repeat fracture. A titanium adapter sleeve must be used with the new ceramic head. A highly cross-linked polyethylene (or new ceramic) liner must also be used.
Question 1711
Topic: 3. Adult Reconstruction (Hip & Knee)
A 55-year-old male with a history of a high tibial osteotomy (HTO) 10 years ago now requires a total knee arthroplasty (TKA) for severe osteoarthritis.
What is the most significant intraoperative challenge the surgeon should anticipate, and what is an appropriate maneuver to address it?
A common complication following a high tibial osteotomy (HTO), particularly opening wedge, is patella baja (inferred from the image reference and clinical history). Patella baja makes eversion of the patella and adequate exposure of the joint extremely difficult during TKA. If standard exposure techniques are insufficient, a lateral retinacular release, rectus snip, or a tibial tubercle osteotomy (TTO) may be required to safely mobilize the extensor mechanism without avulsing the patellar tendon.
Question 1712
Topic: 3. Adult Reconstruction (Hip & Knee)
A 68-year-old female presents to the clinic complaining of a painful popping sensation at the anterior aspect of her knee when extending from a flexed position, one year after an uncomplicated posterior-stabilized total knee arthroplasty (PS-TKA).
What is the primary etiology of this specific complication?
Correct Answer & Explanation
. Impringement of a hypertrophic fibrous nodule at the superior pole of the patella into the femoral intercondylar box.
Explanation
The presentation is classic for Patellar Clunk Syndrome, which occurs almost exclusively in posterior-stabilized (PS) knee designs. It is caused by the formation of a fibrosynovial nodule at the undersurface of the quadriceps tendon, just proximal to the superior pole of the patella. As the knee flexes, this nodule drops into the intercondylar box of the femoral component. Upon active extension (usually around 30 to 45 degrees), the nodule gets caught on the anterior edge of the box and abruptly 'clunks' out, causing pain and a palpable catch. Treatment usually involves arthroscopic debridement of the nodule.
Question 1713
Topic: 3. Adult Reconstruction (Hip & Knee)
A 60-year-old male with medial compartment osteoarthritis of the knee undergoes evaluation for a unicompartmental knee arthroplasty (UKA).
According to standard Kozinn and Scott criteria, which of the following is an absolute contraindication to performing a medial UKA?
Correct Answer & Explanation
. Inflammatory arthropathy
Explanation
Inflammatory arthropathy (e.g., Rheumatoid arthritis) is a classic absolute contraindication for unicompartmental knee arthroplasty (UKA) because the disease process is systemic and will inevitably affect the remaining compartments. The classic Kozinn and Scott criteria for UKA include: non-inflammatory osteoarthritis, intact ACL, correctable varus deformity (<15 degrees), flexion contracture < 15 degrees, and historically age > 60 and weight < 82 kg (though age and weight criteria have been widely challenged and expanded in modern practice). Inflammatory arthritis remains universally recognized as a contraindication.
Question 1714
Topic: 3. Adult Reconstruction (Hip & Knee)
A 74-year-old female presents to the emergency department after a ground-level fall. Five years ago, she underwent an uncomplicated cementless THA.
Radiographs reveal a periprosthetic femur fracture extending around the distal tip of the femoral stem. The stem is visibly loose on radiographs with subsidence. What is the most appropriate surgical treatment?
Correct Answer & Explanation
. Revision to a long, fully porous-coated or fluted tapered, diaphyseal-engaging stem.
Explanation
This is a Vancouver B2 periprosthetic femur fracture: the fracture occurs around or just below the stem (type B), and the stem is loose (type B2), but with adequate proximal bone stock (unlike type B3, where proximal bone stock is inadequate). The standard of care for a Vancouver B2 fracture is revision of the femoral component to bypass the fracture using a long, diaphyseal-engaging stem (often fluted and tapered, uncemented) to achieve distal fixation, combined with appropriate fracture reduction and cerclage cabling if necessary. ORIF alone (Option 1) is indicated for Vancouver B1 fractures (stem well-fixed). Proximal femoral replacement is reserved for Vancouver B3.
Question 1715
Topic: 3. Adult Reconstruction (Hip & Knee)
During a primary posterior-stabilized (PS) total knee arthroplasty, the surgeon places trial components. Upon assessment of gap kinematics, the joint space is symmetrically balanced and stable in full extension, but tight and difficult to flex past 90 degrees. Which of the following is the most appropriate next surgical step to balance the knee?
Correct Answer & Explanation
. Recut the proximal tibia to increase the posterior slope.
Explanation
The knee is tight in flexion but balanced in extension. Interventions must address the flexion gap without altering the extension gap. Decreasing the anteroposterior (AP) size of the femoral component (using a smaller femoral component matched to the anterior cortex, which resects more posterior condyle) will increase the flexion gap. Alternatively, increasing the posterior slope of the tibial cut will selectively increase the flexion gap without significantly affecting the extension gap. Resecting more distal femur only affects the extension gap. A PS knee does not have an intact PCL. Increasing poly thickness would tighten both gaps.
Question 1716
Topic: 3. Adult Reconstruction (Hip & Knee)
A 54-year-old male presents with a painful total hip arthroplasty 5 years postoperatively. His bearing surface is a metal-on-polyethylene construct. Radiographs show a well-fixed stem and cup with no osteolysis. Joint aspiration is negative for infection, but fluid analysis is black and turbid. Blood tests reveal significantly elevated cobalt levels with normal chromium levels. What is the most likely diagnosis?
Correct Answer & Explanation
. Adverse local tissue reaction (ALTR) secondary to trunnionosis.
Explanation
The clinical picture describes an Adverse Local Tissue Reaction (ALTR) or ALVAL (aseptic lymphocyte-dominated vasculitis-associated lesion) secondary to mechanically assisted crevice corrosion (MACC), commonly known as trunnionosis. This occurs at the modular head-neck junction (the trunnion). In a metal-on-polyethylene THA, a characteristic finding of trunnionosis is an isolated, significant elevation of serum cobalt levels with normal or near-normal serum chromium levels, because the wear and corrosion products primarily release cobalt from the CoCr head. If this were a metal-on-metal bearing wear issue, both cobalt and chromium would typically be elevated.
Question 1717
Topic: 3. Adult Reconstruction (Hip & Knee)
According to the 2018 International Consensus Meeting (ICM) criteria for Periprosthetic Joint Infection (PJI), which of the following synovial fluid biomarkers acts as a highly specific indicator of PJI, functioning as an antimicrobial peptide released by neutrophils?
Correct Answer & Explanation
. Alpha-defensin
Explanation
Synovial alpha-defensin is an antimicrobial peptide released by active neutrophils in response to pathogens. It is incorporated into the 2018 ICM criteria as a major biomarker for diagnosing PJI. It is highly specific and sensitive for infection and has the advantage of remaining accurate even in the presence of systemic inflammatory conditions or prior antibiotic administration. CRP and IL-6 are inflammatory markers, leukocyte esterase is an enzyme produced by WBCs (also a valid test, but alpha-defensin is the specific peptide asked about), and D-dimer is a fibrin degradation product (used as a serum marker for PJI).
Question 1718
Topic: 3. Adult Reconstruction (Hip & Knee)
In the manufacturing of highly cross-linked polyethylene (HXLPE) for total hip arthroplasty, the irradiation process creates free radicals that improve wear resistance but risk long-term oxidation and structural failure. To eliminate these free radicals, the material is often remelted or annealed. Which of the following mechanical properties is most significantly decreased as a direct result of this cross-linking and remelting process?
Correct Answer & Explanation
. Fatigue crack propagation resistance
Explanation
Highly cross-linked polyethylene (HXLPE) drastically reduces the volumetric wear rate in THA, minimizing osteolysis. The cross-linking is achieved by irradiation. However, irradiation leaves behind free radicals. To eliminate free radicals and prevent long-term oxidation, the PE is heated (remelted or annealed). This extensive cross-linking and subsequent thermal treatment significantly decreases the material's fatigue crack propagation resistance, yield strength, and ultimate tensile strength. This is why HXLPE is generally avoided in components requiring high fatigue strength and thin polyethylene, such as highly constrained liners or older thin TKA inserts.
Question 1719
Topic: 3. Adult Reconstruction (Hip & Knee)
A 35-year-old male with a history of a severe nickel allergy requires a primary total knee arthroplasty for post-traumatic osteoarthritis. Standard cobalt-chromium (CoCr) implants contain small amounts of nickel. To avoid a type IV hypersensitivity reaction, which of the following is the most appropriate alternative femoral component material?
Correct Answer & Explanation
. Oxidized zirconium (Oxinium)
Explanation
Standard cobalt-chromium (CoCr) alloy implants contain trace amounts of nickel and are a known risk factor for metal hypersensitivity (a Type IV delayed hypersensitivity reaction). For patients with a documented severe nickel allergy, oxidized zirconium (Oxinium) or purely titanium femoral components are the indicated alternatives. Oxidized zirconium undergoes a process that changes its surface to a hard ceramic (zirconia), eliminating metal ion release at the surface while retaining the fracture resistance of a metal core. Trabecular metal (tantalum) is used for bone ingrowth surfaces, not as an articulating femoral surface.
Question 1720
Topic: 3. Adult Reconstruction (Hip & Knee)
During a primary posterior-stabilized total knee arthroplasty (TKA), after the preliminary bone cuts have been made, trial components are placed. The surgeon notes that the joint is tight in 90 degrees of flexion but symmetric and well-balanced in full extension. Which of the following is the most appropriate next step to correct this mismatch?
Correct Answer & Explanation
. Decrease the size of the femoral component
Explanation
A knee that is tight in flexion but balanced in extension indicates a tight flexion gap. Recutting the proximal tibia or changing the polyethylene thickness would affect BOTH the flexion and extension gaps equally. Recutting the distal femur affects ONLY the extension gap. Decreasing the size of the femoral component (which decreases the AP dimension of the femur) increases the flexion gap without affecting the extension gap, thereby balancing the knee.
Test Yourself
Switch to an interactive, timed exam simulation to truly master this topic.