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 1741
Topic: Total Knee Arthroplasty (TKA)
Kinematic alignment in total knee arthroplasty aims to differ from traditional mechanical alignment primarily by doing which of the following?
Correct Answer & Explanation
. Cutting the proximal tibia strictly perpendicular to its mechanical axis
Explanation
Kinematic alignment uses the patient's native, pre-arthritic articular geometry to guide bony resections. It aims to co-align the axes of the components with the three kinematic axes of the normal knee, rather than forcing a neutral mechanical axis.
Question 1742
Topic: Total Hip Arthroplasty (THA)
A 55-year-old female presents with persistent anterior groin pain exacerbated by active straight leg raise 6 months after a total hip arthroplasty. What is the most common iatrogenic cause of this condition?
Correct Answer & Explanation
. Retroversion of the acetabular component
Explanation
Iliopsoas impingement post-THA is classically caused by anterior overhang of the acetabular shell. The iliopsoas tendon rubs against the prominent metal edge during active flexion, causing pain and tendinitis.
Question 1743
Topic: 3. Adult Reconstruction (Hip & Knee)
A patient with a history of severe contact dermatitis to cheap jewelry requires a total knee arthroplasty. To prevent a severe metal hypersensitivity reaction, the surgeon should utilize implants specifically avoiding which of the following elements?
Correct Answer & Explanation
. Titanium
Explanation
Nickel is the most common sensitizing metal in orthopedic implants, often causing hypersensitivity reactions in susceptible individuals. Cobalt-chromium alloys contain trace amounts of nickel, whereas Oxinium (oxidized zirconium) or all-titanium components are preferred in allergic patients.
Question 1744
Topic: 3. Adult Reconstruction (Hip & Knee)
During a posterior-stabilized total knee arthroplasty, the surgeon uses spacer blocks and notes that both the flexion and extension gaps are excessively tight and symmetric. Which of the following is the most appropriate next step in balancing the knee?
Correct Answer & Explanation
. Recess the posterior cruciate ligament
Explanation
When both the flexion and extension gaps are symmetrically tight, the problem lies on the tibial side. Resecting more proximal tibia will symmetrically increase both the flexion and extension gaps.
Question 1745
Topic: Total Hip Arthroplasty (THA)
A 70-year-old female is evaluated for a total hip arthroplasty (THA). Radiographs reveal a prior L2-S1 posterior spinal fusion. Standing and sitting lateral spinopelvic radiographs demonstrate a change in pelvic tilt of 5 degrees. Based on her spinopelvic biomechanics, what THA component positioning strategy is recommended to minimize dislocation risk?
Correct Answer & Explanation
. Increase acetabular cup anteversion
Explanation
This patient has a stiff spinopelvic junction (<10 degrees change in pelvic tilt from standing to sitting). To compensate for the lack of increased pelvic retroversion while sitting, the surgeon should increase the acetabular cup anteversion and/or inclination to prevent anterior impingement and posterior dislocation.
Question 1746
Topic: Total Hip Arthroplasty (THA)
A 59-year-old active woman undergoes elective total hip replacement in which a posterior approach is used. She has minimal pain and is discharged to home 2 days after surgery. Four weeks later, she dislocates her hip while shaving her legs. She undergoes a closed reduction in the emergency department. Postreduction radiographs show a reduced hip with well-fixed components in satisfactory alignment. What is the most appropriate management of this condition from this point forward?
Correct Answer & Explanation
. Observation and patient education regarding hip dislocation precautions
Explanation
First-time early dislocations are often treated successfully without revision surgery, especially when no component malalignment is present. In this clinical scenario, it appears the patient would benefit from better education about dislocation precautions. Hip orthoses are of questionable benefit unless the patient is cognitively impaired. Revision surgery can be successful but is usually reserved for patients with recurrent dislocations.
Question 1747
Topic: 3. Adult Reconstruction (Hip & Knee)
A 26-year-old man has had a 2-year history of pain and stiffness after sustaining a comminuted olecranon fracture. Treatment at the time of injury consisted of open reduction and internal fixation with tension band wiring. Examination reveals motion of 45 degrees to 110 degrees and pain throughout the arc of motion. Resisted flexion and extension are painful. Forearm rotation is normal. Radiographs are shown. Treatment should consist of
Correct Answer & Explanation
. hardware removal and elbow joint release with splinting.
Explanation
The patient has posttraumatic arthritis of the elbow; therefore, the treatment of choice is hardware removal and soft-tissue releases with splinting to avoid recurrence of contractures. The combination of pain and stiffness in an elbow that has sustained significant joint surface damage renders it unresponsive to simple soft-tissue releases and heterotopic bone excision. Joint distraction and interposition arthroplasty offer the possibility of maintaining motion and relieving pain as a later salvage procedure. Joint replacement should not be performed in young, active, strong individuals because the prosthesis will fail quickly and complications will develop.
Question 1748
Topic: 3. Adult Reconstruction (Hip & Knee)
Which of the following factors can contribute to patellar subluxation following routine total knee arthroplasty?
Correct Answer & Explanation
. Internal rotation of the tibial component
Explanation
Internal rotation and medial placement of the tibial component results in lateralization of the tibial tubercle with an increase in the Q angle. Excessive valgus alignment of the mechanical axis, or insufficient correction of preoperative valgus, has a similar effect on the Q angle, and both can result in a higher rate of tracking problems.
Question 1749
Topic: Total Knee Arthroplasty (TKA)
A 70-year-old woman has a 3-year history of gradually increasing diffuse and global right knee pain. Her main issues are difficulty with stairs, stiffness with prolonged sitting, and swelling. She has taken NSAIDs and has received intra-articular steroid injections, all with decreasing efficacy. Her right knee examination reveals a range of motion of 15° to 80° with a fixed deformity to varus and valgus stress. Her symptoms are no longer manageable nonsurgically. Radiographs reveal a 30-degree mechanical axis deformity. The deformity shown in the figure below is predominantly associated with:
Correct Answer & Explanation
. a hypoplastic lateral femoral condyle.
Explanation
In the setting of valgus deformities, TKA poses different challenges than those encountered when varus deformities are present. Most valgus alignment is attributable to a deformity of the distal femur rather than of the proximal tibia. One of the major anatomical differences is a hypoplastic lateral femoral condyle which, when not recognized and used as a rotational reference point, can lead to internal rotation of the femoral component.
Question 1750
Topic: 3. Adult Reconstruction (Hip & Knee)
Figure 194 is the radiograph of a 71-year-old woman who had a right total hip arthroplasty 4 months ago; now she has tripped and fallen. She is unable to continue weight-bearing activity on her right leg, but denies pain or ambulation issues prior to her fall. She is seen in the emergency department. What is the best treatment for this patient?
Correct Answer & Explanation
. Revise the femoral stem bypassing the fracture by 2 cortical widths and ORIF the fracture
Explanation
This patient has sustained a periprosthetic hip fracture consistent with a Vancouver B2 pattern. The femoral stem must be revised by bypassing the fracture and simultaneously providing stability through fixation. Method of fixation is dependent upon fracture pattern, and, in this case, the medial fracture fragment is better suited for cerclage fixation. Loosening of the stem precludes simply fixing the fracture with cables, plates, or allograft struts, and there is no need to allow the fracture to heal prior to placing a new stem if the fracture is adequately stabilized with fixation.
Question 1751
Topic: 3. Adult Reconstruction (Hip & Knee)
A 65-year-old male presents with groin pain 5 years after a primary metal-on-polyethylene total hip arthroplasty. Laboratory analysis shows elevated serum cobalt levels and normal chromium levels. Hip aspiration is negative for infection. What is the most likely source of the elevated metal ions?
Correct Answer & Explanation
. Mechanically assisted crevice corrosion at the head-neck junction
Explanation
Elevated cobalt out of proportion to chromium in the setting of a non-metal-on-metal bearing (e.g., metal-on-polyethylene) is highly suggestive of mechanically assisted crevice corrosion (trunnionosis) at the modular head-neck junction.
Question 1752
Topic: Total Knee Arthroplasty (TKA)
During a total knee arthroplasty, which of the following component malpositions is most likely to result in lateral patellar tracking and potential subluxation?
Correct Answer & Explanation
. Internal rotation of the femoral component
Explanation
Internal rotation of the femoral component and internal rotation of the tibial component both increase the Q angle, leading to lateral patellar tracking and potential subluxation. Medialization of the femoral component and medialization of the patellar component also worsen lateral tracking.
Question 1753
Topic: 3. Adult Reconstruction (Hip & Knee)
According to consensus criteria, which of the following is the most appropriate indication for debridement, antibiotics, and implant retention (DAIR) in a patient with a periprosthetic joint infection following TKA?
Correct Answer & Explanation
. Acute hematogenous infection with symptom onset 10 days ago and a well-fixed implant
Explanation
DAIR is indicated for acute postoperative infections (typically < 4 weeks from surgery) or acute hematogenous infections (typically < 3-4 weeks of symptom onset) in the setting of well-fixed components and a healthy soft-tissue envelope. Chronic sinus tracts and loose components are absolute contraindications to DAIR.
Question 1754
Topic: Total Hip Arthroplasty (THA)
A 55-year-old woman undergoes a primary THA using a ceramic-on-ceramic bearing. Two years later, she complains of an audible squeaking sound from her hip during walking, without associated pain. Radiographs show well-fixed components. Which of the following is most strongly associated with the development of squeaking in ceramic-on-ceramic THA?
Correct Answer & Explanation
. Edge loading due to component malposition
Explanation
Squeaking in ceramic-on-ceramic THA is most commonly associated with edge loading, which typically occurs due to component malposition (e.g., excessive cup anteversion, excessive cup abduction, or extreme combinations causing microseparation during gait).
Question 1755
Topic: Total Knee Arthroplasty (TKA)
During a cruciate-retaining TKA, the surgeon notes that the knee is well balanced in extension but is tight in flexion, demonstrating restricted flexion and anterior liftoff of the tibial trial tray. Which of the following is the most appropriate next step to balance the knee?
Correct Answer & Explanation
. Release the posterior cruciate ligament
Explanation
A tight flexion gap with a balanced extension gap in a cruciate-retaining TKA, characterized by anterior liftoff of the tibial tray, is often caused by a tight posterior cruciate ligament (PCL). Releasing or recessing the PCL will increase the flexion gap without affecting the extension gap.
Question 1756
Topic: 3. Adult Reconstruction (Hip & Knee)
A 72-year-old female presents after a fall with a spiral fracture around her cementless THA stem. The stem has subsided 1.5 cm compared to previous radiographs. Bone stock is deemed adequate. According to the Vancouver classification, what is the most appropriate management?
Correct Answer & Explanation
. Revision to a long uncemented diaphyseal-engaging splined tapered stem
Explanation
This is a Vancouver B2 periprosthetic femur fracture (fracture around the stem, loose stem, adequate bone stock). The gold standard management is revision of the femoral component using a long uncemented diaphyseal-engaging stem (fluted, tapered) to bypass the fracture site by at least two cortical diameters.
Question 1757
Topic: 3. Adult Reconstruction (Hip & Knee)
In a revision total hip arthroplasty for a patient with massive acetabular bone loss, what radiographic finding best differentiates a pelvic discontinuity from a severe but continuous defect?
Correct Answer & Explanation
. A visible fracture line extending through the anterior and posterior columns
Explanation
Pelvic discontinuity is defined as a complete separation of the superior pelvis (ilium) from the inferior pelvis (ischium and pubis). The pathognomonic radiographic sign is a visible transverse fracture line extending completely through both the anterior and posterior columns.
Question 1758
Topic: Total Hip Arthroplasty (THA)
To optimize stability and minimize impingement in THA, the concept of combined anteversion is often utilized. If the acetabular cup is placed in 15 degrees of anteversion, what is the ideal target for femoral stem anteversion to achieve a standard combined anteversion of 35-40 degrees?
Correct Answer & Explanation
. 20-25 degrees
Explanation
Combined anteversion is the sum of cup anteversion and femoral stem anteversion. The classic target range (Ranawat/Dorr) is 25-45 degrees. If the cup is at 15 degrees, a femoral anteversion of 20-25 degrees will achieve a combined anteversion of 35-40 degrees, providing optimal stability.
Question 1759
Topic: Total Knee Arthroplasty (TKA)
A 68-year-old man who underwent primary TKA 4 years ago presents with an inability to actively extend his knee following a fall. Clinical exam reveals a palpable gap at the superior pole of the patella. What is the most reliable surgical option for reconstruction of this chronic extensor mechanism disruption?
Correct Answer & Explanation
. Extensor mechanism allograft or synthetic mesh reconstruction
Explanation
Chronic or severe extensor mechanism disruptions in the setting of a TKA (especially large quadriceps defects or patellar tendon avulsions) have high failure rates with primary repair. Extensor mechanism allograft reconstruction or synthetic mesh reconstruction are the most reliable options to restore continuity.
Question 1760
Topic: 3. Adult Reconstruction (Hip & Knee)
A 58-year-old woman presents with persistent, unexplained pain and swelling in her knee 2 years after a primary TKA. Joint aspiration is negative for infection. A synovial biopsy demonstrates a perivascular lymphocytic infiltrate with macrophages containing metal wear debris. Which of the following is the most likely diagnosis?
ALVAL is a delayed-type hypersensitivity reaction to metal ions. It is characterized histologically by a perivascular lymphocytic infiltrate. It is a diagnosis of exclusion after infection and mechanical failure have been definitively ruled out.
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