Fracture mechanics. A comparison study of torsional stress on bone.

Fractures that result from torsional loading of shafts in mechanical systems of nonbiologic materials generate a fracture line that forms a 45 degrees angle to an axis that is perpendicular to the direction of torsional loading on the shaft. As tension and compression are applied to these isotropic substances, the angle of fracture increases and decreases, respectively. Understanding how these forces, particularly compressive forces, generate elongation of a spiral fracture increases the ability to predict the extent of injury to bone. Fibular and metatarsal fractures are of primary importance to the podiatric physician, but any spiral fracture may be subject to torsional loading. Thus the principles stated here apply to the entire skeletal system. The purpose of this article is to provide a better understanding of the mechanics behind the causes and characteristics of fractures and to explore whether these same factors apply to the fracture mechanics of bone.

Flexor digitorum accessorius longus muscle.

The flexor digitorum accessorius longus muscle was encountered during routine dissection of the posteromedial region of the left ankle of an 84-year-old female cadaver, by a first year podiatric medical student, in a lower extremity anatomy laboratory session. The purpose of this article is to describe the flexor digitorum accessorius longus muscle as it appeared in the cadaver; to provide background information on the muscle; and provide clinical implications for the podiatric medical practitioner.