Structured oral examination question 1: TKR in valgus knee

1. EXAMINER: This is a radiograph of a 72-year-old lady complaining of pain and gradual deformity of both knees. She has been referred to your clinic to be considered for total knee arthroplasty. What can you see? (Figure 3.1.)

2. CANDIDATE: These are weightbearing anteroposterior (AP) views of a 72-year-old lady demonstrating narrowing of joint spaces with bone-on-bone contact in the lateral compartments of both knees. There is early arthrosis affecting the medial compartments of both knees. There is moderate valgus deformity.

3. EXAMINER: What conditions are associated with this pattern of joint disease?

4. CANDIDATE: The valgus deformity of the knee with arthritis is commonly seen in women and in inflammatory joint conditions such as rheumatoid arthritis. It can also occur in primary osteoarthritis, overcorrection of high tibial osteotomy (HTO), post-traumatic arthritis following lateral meniscectomy and osteonecrosis.

5. EXAMINER: What are the perioperative considerations for total knee arthroplasty in valgus knee?

6. CANDIDATE: The preoperative assessment should include a thorough history and examination to establish if there are any predisposing factors such as rheumatoid arthritis and the success of non-surgical management. The competency of the knee collateral ligaments and degree of deformity correction should be assessed in order to plan on type of implants. I would use a medial parapatellar because this gives good access to the whole knee and better soft tissue cover. I am aware that a lateral approach can also be used.

7. EXAMINER: What is the theoretical advantage of a lateral approach?

8. CANDIDATE: It is a direct approach providing easier access and preserves the neurovascular supply to the extensor mechanism.

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