Bone deformation recorded in vivo from strain gauges attached to the human tibial shaft.

A strain gauge rosette was attached to the midshaft of a man's tibia. This demonstrated that during every stride the bone surface was subjected to a number of discrete deformation cycles. During each cycle the bone was deformed from a particular direction, released at least partially and then deformed from another direction. This feature has been observed from a number of sites in experimental animals. The largest deformation occurred while the subject was running; the principal tension then reached 850 microstrain applied in line with the bone's long axis at 13 times 10-3 microstrain per second. When walking the largest deformation occurred prior to 'toe off'; compression was then the larger principal strain about minus 400 microstrain applied at 37 degrees to the bone's long axis at minus 4 times 10-3 microstrain per second. These strain values are the same order of size as those recorded from the long bones of sheep and pigs during their locomotion.