Abstract
Aims: This study describes the varied anatomic geometry of the proximal femur as it relates to cementless femoral stem design. Methods: Femoral head offset, neck-shaft angle, and canal width were measured on frontal plane radiographs of undiseased hips from 47 female and 39 male North American patients. Average age and height was 66(21–89) years and 170(152- 193)cm, respectively. Patients were positioned supine with inward pointed toes to achieve femoral internal rotation during radiography. Measurements were corrected for magniþcation and correlated with demographic data. Results: The average femoral head offset and neck-shaft angle was 37±6(25- 53)mm and 131û±6û(119û-145û), respectively. Distal canal width aver aged 11±2(5–16)mm and the canal ßare index was normal in 77% of the femurs, stovepipe in 8% and ßuted in 15%. Signiþcant correlations were as follows. As patient height increased, femoral head offset and distal canal width also increased (p< 0.05). As patient age increased, distal canal width increased and canal ßare index decreased (p< 0.05), becoming more stovepipe in shape. Femoral head offset decreased with increased neck shaft angle. Conclusions: Comparing these data with published data from Eastern populations is useful for determining appropriate cementless stem sizes applicable to different populations. Variation in femoral head offset supports the use of different neck lengths, neck-shaft angles or medialized necks to provide surgeons with stems suitable for restoring leg length and balancing soft tissues. The width of the distal endosteal canal varied widely, suggesting that some patients may beneþt from a smaller or larger distal stem diameter for a given proximal stem size.
Theses abstracts were prepared by Professor Dr. Frantz Langlais. Correspondence should be addressed to him at EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
