MANAGEMENT OF THE ANATOMIC DIFFERENCES IN FEMALE AND MALE DISTAL FEMURS IN TOTAL KNEE REPLACEMENT SURGERY

Abstract

Frequently surgeons performing total knee replacements are faced with the dilemma of whether to notch the anterior cortex or overhang the medial and/or lateral cortices when implanting the femoral component. This is almost always seen in female patients. There is also a higher incidence of patellar alignment problems in female patients post total knee replacement. A unique 3D to 3D matching study of 202 cadaveric femurs has demonstrated a significant difference in the average comparable shapes of male versus female distal femoral anatomy. For the same AP dimension, female distal femurs are more than 5mm narrower. Also the angle formed between the anterior condyles and the posterior condyles are significantly different with the female being more trapezoidal in shape.

Most existing total knee femoral component designs follow the ratio similar to that found in the average male distal femur. Options for management of this gender variability have been either utilizing instrumentation that references the anterior cortex to avoid notching or placing additional flexion on the distal femoral cut to allow downsizing. Both techniques are potentially problematic. Total knee implants systems are now utilizing this anthropomorphic data to redesign for separate male and female femoral components taking into consideration the relatively narrower female distal condylar width, lower medial anterior femoral condyle, and greater patellofemoral Q-angle.