Lower-limb alignment and posterior tibial slope in Pakistanis: a radiographic study.

PURPOSE To assess the lower-limb alignment and posterior tibial slope in Pakistanis. METHODS 40 male and 19 female healthy Pakistanis aged 20 to 45 years were recruited. A full weight-bearing anteroposterior radiograph of the entire lower limb of each subject was obtained. The axial alignment was measured based on the centres of the femoral head, knee, and ankle. The tibiofemoral (TF) angle, knee joint line obliquity angle (angle J), and posterior tibial slope were determined. RESULTS The mean TF angle was more varus in men than women (178.4 degrees vs. 180.0 degrees, p<0.001). The mean angle J was more medially inclined in men than women (93.4 degrees vs. 91.4 degrees, p=0.007). The mean medial tibial slope was greater in women than men (16.0 degrees vs. 12.5 degrees, p<0.001). The posterior tibial slope was greater in women than men (14.1 degrees vs. 12.5 degrees, p=0.02), and was greater than the 5 degrees to 10 degrees commonly reported. CONCLUSIONS Knee alignment and geometry vary in different population subsets. With regard to total knee arthroplasty, the more medially inclined angle J in Pakistani men suggests that an anteroposterior cut of the distal femur should be in increased external rotation, compared with Pakistani women. Whereas the greater posterior tibial slope in Pakistanis suggests that a proximal tibial cut with a greater posterior tibial slope may reduce the chance of tibial loosening and increase postoperative knee range of motion, especially when using posterior cruciate ligament-retaining designs.