A 55-year-old with end-stage rheumatoid arthritis of the knee undergoes total knee arthroplasty. Intraoperatively, the flexion and extension gaps are found to be unequal, with the flexion gap larger than the extension gap. What is the best intraoperative solution?

• A Increase the tibial slope by performing an additional anterior tibial resection
• B Downsize the femoral component to equalise the flexion gap to the extension gap
• C Upsize the femoral component and/or increase distal femoral resection to tighten the flexion gap ✓
• D Release the posterior capsule to equalise the gaps

Explanation

In TKA, balanced flexion and extension gaps are fundamental for stability and kinematics. When the flexion gap is larger than the extension gap (flexion laxity), options to tighten the flexion gap include: upsizing the femoral component (increases AP dimension, filling the flexion gap), increasing distal femoral resection (increases extension gap to match; combined with a thicker insert), or reducing posterior condylar offset. Downsizing the femoral component would worsen the flexion gap inequality. Increasing tibial slope opens the flexion gap further.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.