Comparative study of femoral diaphyseal morphometry in two male populations, in France and a French West Indies island: an example of clinical relevance of comparative anatomy for orthopedic practice.

Our aim, through a comparative study of two populations, one European and the other Afro-Caribbean, was to find out whether there were differences in radiographic measurements of femoral diaphyseal canal diameter, thickness of the medial and lateral cortex, and global diaphyseal diameter. We studied the nailed femurs of adult males in a population of 54 Europeans and 52 Afro-Caribbeans. Both populations were comparable in terms of age, height and weight. The measurements were taken with a ruler on the narrowest area of the hourglass, the isthmus, on an antero-posterior radiograph. The diameter of the femoral canal was classified into three intervals: <13 mm, 13-14 mm and >14 mm. The femoral canal diameter was significantly larger in the European patients, 14.3 (11-19) versus 13.4 (11-15.6), while the thickness of the lateral cortex was significantly larger in the Afro-Caribbean patients, 8.50 (6-12) versus 7.72 (5.4-11.5). Patient distribution according to the intervals was different in both groups: 59% of the Afro-Caribbeans were in the average interval versus 24.1% of the Europeans. For nearly 53.7% of the Europeans, the diameter of the femoral canal fell in the last interval versus 15.4% of the Afro-Caribbeans. The fact that the femoral canal is narrower in the Afro-Caribbean population may be linked to a thicker lateral cortex. The diameters of the nails used were larger in the European population, 12.6 mm (10-15) versus 12.1 mm (11-14) in the Afro-Caribbean population. The global diameters of both populations' femurs were similar (28.9 mm for the European sample vs. 29 mm). The present study may have an impact on the implants used in the orthopedic surgery (intramedullary nailing, arthroplasty implants). The range of usable implants must be complete and there must be precise pre-operative planning. A study of computed tomography scans could complement our measurements.