DISTAL FEMORAL RESECTION IN TOTAL KNEE JOINT REPLACEMENT

Abstract

Total Knee Joint Replacement is mostly commonly performed using a measured resection technique. When the PCL is retained 9mm of bone is resected off the distal femur. If the PCL is excised 11m of bone is resected. Computer assisted total knee joint replacement will guide the surgeon to perform the optimal distal femoral resection to gain neutral alignment and full post operative extension.

Three hundred TKJR’s were performed by one surgeon using the De Puy Ci navigation system. A ligament balancing technique is used whereby a neutral tibial resection is performed. A ligament tensor is inserted in extension and flexion. The navigation system then performs an optimization process whereby the distal femoral cut is calculated to give a neutral mechanical axis and 0° of knee extension. Data was collected measuring the distal femoral resection in the PCL retained and resected knees.

The distal femoral cut required to achieve full extension for the PCL retaining TKJR ranged from 5 – 15mm. The mean was 11.2mm. The distal femoral cut required to achieve full extension for the PCL sacrificing TKJR ranged from 5 – 15mm. The mean was 10.8mm. There was no difference between the two groups (p=0.07). Both the PCL retaining and sacrificing TKJR distal resections correlated with the preoperative flexion deformity, i.e. patients with a greater fixed flexion deformity required a greater distal femoral resection to achieve full extension

There is a wide variation in the distal femoral cut to achieve full extension in TKJR. It is accepted that a smaller distal resection is required for a PCL retaining than a PCL sacrificing TKJR. Our study refutes this premise. A greater femoral resection is required if there is a greater fixed flexion deformity. A measured resection technique will result in a large percentage of patients with a fixed flexion deformity following TKJR