School of Anatomical Sciences, Univerity of the Witwatersrand
Friday 11:30-11:45, Galleria North
A logical expectation of bone functional adaptation is that the external geometry of long bone diaphyses at different loci evidence poor covariance. Previous analyses of lower limb a-p/m-l diaphyseal indices in Homo sapiens confirm no correlation of length and specific a-p/m-l proportions. Buxton (Buxton, 1938), directly assessed correspondences in a-p/m-l indices in associated elements and found a moderate correlation (r = 0.4441 [right]) of diaphyseal flattening in the femur and tibia. A large global sample of femora (n=392) confirm a low, yet significant, correlation of pilasteric and platymeric indices (rho = 0.367; P<0.001) with minimal contrasts in males and females. Not surprisingly, a-p/m-l indices of the tibial midshaft and proximal diaphysis were substantially higher, with minimal sex-specific contrasts.
Pooled-sex specimens encompassing an age-at-death of ~ 32 weeks in-utero to ~ 10 years evidence a low (significant) correlation of femur length and a-p/m-l indices, yet no correspondence in pilasteric and platymeric indices. Contrastingly, tibial a-p/m-l proportions are insignificantly correlated with length, but midshaft and proximal a-p/m-l indices are highly correlated. Diaphyseal cross-sectional areas of the lower limb are strongly correlated with length and confirm the latent plasticity of femoral diaphyseal form, particularly its proximal aspect. In contrast, external tibial diaphyseal geometry is highly constrained during ontogeny and in adulthood. In contrast with adults, a-p/m-l dimensions of femoral and tibial diaphyses converge on expectations of Elastic Similarity Scaling (LSR) with overall length.
This research was funded by the Faculty of Health Sciences, University of the Witwatersrand, the Ford Foundation, and the Palaeontology Scientific Trust