The Effect of Distal Femoral Resection on Passive Knee Extension in Posterior Cruciate Ligament–Retaining Total Knee Arthroplasty

Full passive extension in total knee arthroplasty is predicated on creating a large enough extension gap to accommodate any given combined thickness of femoral and tibial components. Additional distal femoral resection can achieve more passive knee extension. The predictable effect of further distal femoral resection has never been studied. We designed a simple institutional review board–approved, intraoperative study to quantify this effect. Routine posterior cruciate ligament–preserving total knee arthroplasty was performed with measured femoral and tibial resections, yielding full passive extension with trial components. Distal femoral augments were then sequentially applied to the back of the femoral trial component, and passive knee extension was measured. The data show that an average value of 9° of femoral contracture is corrected for every 2 mm of distal femoral resection.