Abstract
Introduction: The anatomy of the proximal femur is an important factor in the design of uncemented femoral prostheses for which the quality of fixation and the associated bony remodelling depend on the primary stability and optimal transmission of forces to the proximal femur. This study looks at the variation in the diameter of the proximal femur with age and sex in a homogeneous population.
Materials and Methods: We studied standardised pre-operative antero-posterior radiographs of the proximal femur of 2,777 patients who have undergone total hip arthroplasty using a custom implant over a 10 year period. The radiographs were corrected for magnification and a measurement made of the endosteal diameter at the narrowest point of the proximal femur. These measurements were used in the design and manufacture of the custom femoral implant.
Results: Of 2777 patients, 1588 were female and 1189 male. The mean age for females was 69.9 years (Range 30–92) and for males 67.2 years (Range 34–92). The mean proximal femoral canal diameter was 12.67mm for females and 13.36mm for males.
The mean diameter of the proximal femur increased from 12.99mm in males less than 60 years to 13.47mm in those of over 60. This increase was not statistically significant (p-value 0.064, 95% CI). In females there was a statistically significant increase in the mean diameter from 11.38mm in the under 60 age group to 12.90mm in those over 60 ( p-value 0.000, 95% CI).
Conclusions: The increase in the diameter of the proximal femur with age especially in females presents a significant challenge to the design and long-term survivability of uncemented femoral components. This is more so when viewed against the already good long term results available for cemented femoral implants.
The abstracts were prepared by Mr Peter Kay, Editorial Secretary. Correspondence should be addressed to British Hip Society, The Hip Centre, Wrightington Hospital, Appley Bridge, Wigan, Lancashire WN6 9EP.
