The role of the calcar femorale in stress distribution in the proximal femur

OBJECTIVE: To investigate the role of the calcar femorale in stress distribution in the proximal femur. METHODS: Twenty-five specimens of proximal femurs were fixed to simulate single-limb stance. Strain gauges were applied to record the strain under different loads. Strain values of 27 selected sites in the proximal femur were recorded and analyzed at the level of 100 N, 200 N, 300 N, 400 N, 500 N, 600 N and 700 N, respectively before and after disruption of the calcar femorale. RESULTS: When a normal load was being borne, strain values measured in the posterior and medial aspects of the proximal femur were greater than those measured in the anterior and lateral aspects, no matter whether the calcar femorale was disrupted or not. However after disruption of the calcar femorale, strain values in the posterior and medial aspects of the proximal femur increased significantly, whereas those of the anterior and lateral aspects decreased significantly. CONCLUSION: The calcar femorale redistributes stress in the proximal femur by decreasing the load in the posterior and medial aspects and increasing the load in the anterior and lateral aspects.