Methods

A posterior approach to the hip was carried out in six fresh cadaveric half pelves. Large Hohmann acetabular retractors were placed anteriorly, over the acetabular lip, and inferiorly, and their relationship to the femoral and obturator nerves was examined.

Methods and Results

Fifty well preserved adult, cadaveric femora were studied. Different points on the proximal and distal femur were recorded using an optoelectronic system based around a commercial navigation system. Definitions were: anterior femoral plane (AFP) derived from nine points on the anterior cortex of the distal femur; posterior condylar plane (PCP) as the plane parallel to the sagittal mechanical axis of the femur and containing the PCA. The anterior femoral cortex was divided into lateral, median and medial areas. Average heights of each of these areas from the PCP were calculated, as were the angles between the PCP and AFP.

Four distinct anterior cortex profiles were seen. In 28 specimens the lateral side had the highest mean height and the medial side had the lowest mean height (Group 1). For 13 specimens the lowest mean height was in the median area (Group 2) but 7 specimens had highest mean height here (Group 3). Only 2 specimens had the highest mean height on the medial side with the lowest mean height on the lateral side (Group 4). The average angle between the AFP and the PCP was 1.3° of external rotation. In Group 1 the AFP angle was more internally rotated (-10° to -2°) compared to the other groups, in particular Group 4 which showed the most external rotation (3° and 4°).