Three dimensional of proximal femoral medullary canal in malays

Diversity of the proximal femora medullary canal diameters between populations is the key issue regarding cementless hip implant. Accurate information of this endosteal diameter is vital for hip stem design and selection prior surgery. We reconstructed three dimensional femoral models from sixty CT datasets and measured the endosteal canal using the commercial CAD software. Threshold profile for CT images was identified 662-1988 HU for compact bone and 148-661 HU for spongial bone. Several measurements were made on the femoral endosteal canal from mediolateral, anteroposterior and oblique planes from the osteotomy level until 150 mm below the center of lesser trochanter. We compared the endosteal diameters with genders and other populations. The results showed that the difference between genders was not significant (p < 0.05) and Malays had smaller medullary canal diameters except at the metaphyseal levels compared with other populations. Other indices and ratios regarding the medullary canal, metaphyseal and flares were calculated and analyzed. The canal flare index (CFI) showed poor correlations (r = 0.14-0.48) with the metaphyseal canal flare index (MCFI) but the cortico-medullary index correlated very well (r = 0.66) with the femoral flare index (FFI). These differences of the femoral endosteal diameters for Asian population anticipate improving the design of the hip prosthesis especially at the metaphyseal region which is crucial for the primary stability.