Patterns of physiological bone torsion in the pelvic appendicular skeletons of domestic fowl.

Femoral, tibiotarsal and tarsometatarsal torsion was measured in 264 domestic fowls. Birds were either a laying strain fed ad libitum, or a broiler strain fed ad libitum or a broiler strain on restricted feed. They were killed at different times up to 24 weeks of age. Femora were normally rotated externally when the transverse axis of the distal articular surface was compared with that of the proximal joint surface. Tibiotarsi were similarly rotated externally but the high incidence of internal torsion in broilers fed ad libitum suggests that internal rotation is pathological. Tarsometatarsi were normally rotated internally. Mild degrees of intertarsal valgus angulation are physiological but asymmetrical angulation and torsion between each limb of individual birds suggests that a pattern of limb dominance occurs in domestic poultry.