Quantification of Indian femur: Dry bone anthropometry in relation to total knee arthroplasty

Abstract

To study the distal femoral anatomy in Indian population via dry femoral bone measurements and to quantify its effect with relation to total knee arthroplasty. Accurate positioning and sizing of femoral components are important for stability and better outcome.Anatomic measurements on 70 adult cadaveric distal femora were performed using a standardized vernier caliper. The femurs were also photographed in both sagittal and coronal view for bowing and length measurements.The mean length was 42.85cm (±2.82). 39 femurs belonged to the right side. There were 45 males and 25 female femurs. The mean sagittal bowing was measured by radius of curvature and found to have a mean of 109.34cm (±25.00). Coronal bow was mostly lateral and with a mean of 4.12° (±2.78). A total of 13 patients had a medial bow with a mean bowing of 1.73° (±1.32). The mean medial AP was 57.67mm (±3.94). Mean lateral AP was 58.42mm (±3.73).Asian knees are generally considered smaller than their western counterparts. Femoral medio-lateral diameter (fML) was comparatively lesser than other ethnicities published in literature (Chinese and Caucasian). No gender based significant difference was found between aspect ratio. Strong positive correlation between the length of femur and fML (p<0.001) and antero-posterior (fAP) diameter (p<0.001) in both sexes underline the requirement of larger sized implants in larger individual. The average aspect ratio is also less than the western knees. Moreover, a negative correlation (p<0.05) between increasing AR and fAP diameter was noted. This has a crucial bearing on the fitting of the implant, permitting or mitigating the over- or under-hang of the implant.The strength of this study is its basis on healthy non-arthritic distal femur data. The analysis provides a morphometric template for a larger study for designing of gender specific Indian knees suited implant.