Tibial anatomy and functional axes

Articular geometry of the tibia has been studied in relation to the functional axis and extra‐articular bone landmarks, using a Cartesian coordinate system. Thirty‐one cadaver limbs were used, 26 of them paired. The donor age range was 61 to 89 years (17 females, 14 males), none of whom showed evidence of significant arthritic deterioration. Most linear parameters were greater in males than females (p < 0.005), and correlations between these parameters were noted, e.g., tibial length versus plateau width (r = 0.7, p < 0.01) with both genders combined. Gender differences occurred in only two of the angular parameters—tibial torsion (p < 0.025) and foot rotation (p < 0.005). For the latter, mean rotation was internal (−5°) for males, and external (11°) for females. No correlations between angular parameters were found. In the paired limbs, there was asymmetrical distribution of just two parameters—varus tilt of the tibial plateau margins (p < 0.005) and lateral deviation of the tuberosity (p < 0.025). The data complement a previous report on the femur. These studies are relevant to the kinematics of the lower limb, design and sizing of resurfacing components, and possibly to the pathogenesis of osteoarthritis.