The porosity of the bone cement interface of 96 human femoral heads prepared for hip resurfacing.

PURPOSE: The porosity of the femoral head prepared for hip resurfacing has not been previously described. This is important as greater pore size increases the penetration of bone cement and excessive cement penetration can cause osteonecrosis. METHODS: 96 osteoarthritic femoral heads were harvested at total hip arthroplasty and prepared for hip resurfacing. The porosity of the bone cement interface in hip resurfacing was calculated from digitised black and white photographs using MatLab software. RESULTS: The mean porosity was 0.63. Increased porosity was associated with larger femoral heads in both the coronal and sagittal dimensions and cysts in the femoral head. It was not associated with gender, age, body mass index (BMI), smoking, alcohol or corticosteroid consumption. CONCLUSION: The porosity of the femoral head has been shown to be 0.63. Future studies of cementing techniques in hip resurfacing should include this porosity in their designs. The surgeon prior to hip resurfacing should consider altering his cementing technique when cysts are present on the preoperative radiographs.