TKR Component Malalignment: Oral Examination Question Uncovered
Key Takeaway
This article provides essential research regarding TKR Component Malalignment: Oral Examination Question Uncovered. Oralexamination question malalignment of total knee replacement (TKR) components, particularly internal rotation of the femoral component, can cause significant complications. This malposition is implicated in patellofemoral maltracking, leading to anterior knee pain, subluxation, fracture, wear, and aseptic loosening. It also results in a tight flexion gap on the medial side of the knee.
A 72-year-old female presents with persistent anterior knee pain and a "clunk" sensation 12 months following a primary TKA. Clinical examination reveals a localized click in mid-flexion. Radiographs demonstrate well-fixed components in acceptable neutral alignment. A lateral radiograph of the patellofemoral joint is shown below.
Based on the radiographic findings and clinical history, what is the most likely diagnosis, and what is your immediate management plan?
Candidate: The most likely diagnosis is Patellar Clunk Syndrome. This is characterized by a fibrous nodule in the suprapatellar pouch. I would manage this conservatively initially with physiotherapy focusing on the quadriceps, but if it remains symptomatic, I would perform an arthroscopic excision of the fibrous nodule.
Candidates often miss the association between patellar clunk and femoral component design (e.g., posterior stabilized designs) or failing to acknowledge that patella baja is a predisposing factor. Furthermore, failing to mention the differential diagnosis (e.g., aseptic loosening or extensor mechanism rupture) as a safety measure before settling on a clinical diagnosis is a significant error.
The candidate should identify this as Patellar Clunk Syndrome, likely secondary to a fibrous nodule forming at the superior pole of the patellar component, often associated with posterior-stabilized TKA designs and patella baja.
Structured Response:
1. Assessment: Confirm the diagnosis via lateral radiograph (showing potential baja) and potentially ultrasound/MRI if the diagnosis is ambiguous.
2. Differential: Rule out polyethylene wear, component loosening, or patellofemoral tracking issues.
3. Management: Discuss non-operative management (physiotherapy for strengthening/range of motion) versus operative management (arthroscopic or open excision of the fibrous band).
4. Prognosis: Mention that arthroscopic excision typically yields excellent results.
