Tibia! overuse injuries may arise following load-induced adaptive bone modeling and remodeling. The mechanism by which bone senses and adapts to its strain environment is enigmatic. While a dose-response relationship exists between the magnitude of applied strain and bone adaptation at the organ level, the absence of maximal tissue response at the site of maximal strain suggests that strain does not directly stimulate bone. Bioelectric environment modifications consequent to induced strain, effected by streaming potentials, may be the basis of signal transduction. To evaluate streaming potentials as a possible signal transducer, the purpose of the study was to establish the relationship of streaming potential magnitude to bone strain magnitude.

Turkey ulnae osteotomy preparations were subjected, in vivo, to axial and bending loads. Streaming potentials were measured from known sites of minimum and maximum engendered strain.

Results revealed, at 1 Hz loading, a moderately strong, positive relationship exists between strain and streaming potentials at sites of minimum and maximum strain under bending loads, and at the maximum strain site under axial loading. Streaming potential differences between sites of maximum and minimum strain under bending and axial high load conditions, however, were not significant. Findings suggest that while streaming potentials exhibit a relationship with strain, an observation which is intuitive, the relationship is complex. Increased intramedullary pressure during loading may modify strain gradient-derived fluid flow, thereby altering streaming potentials, particularly at sites of compression. Intracortical, segment-specific zeta potential variations may also possibly effect variations in streaming potential expression across bone sections.

It is concluded that adaptive responses of bone to chronic loading do not directly reflect transcortical streaming potential magnitudes. Consequently, the use of electrical modalities for the treatment of tibial overuse injuries gains no direct support from these data.