Muscle architecture degeneration in the residual limb following amputation: a pilot study in rabbits

Amputation severely disrupts muscles remaining at the end of the residual limb. We performed a pilot study to determine the effect of amputation on residual muscle architecture. We surgically amputated one hind paw in two rabbits. At two weeks post-surgery, we euthanized the rabbits, fixed both hindlimbs (intact and residual) in formalin, and removed select muscles (gastrocnemius, soleus, tibialis anterior) for architecture measurement. Muscle mass, muscle length, normalized fiber length, and physiologic cross-sectional area tended to be lower in the residual limb than in the intact limb for all muscles, with differences most pronounced in the soleus. These preliminary data reveal broad, varied muscle degeneration after amputation that could impair prosthetic and residual limb function (if the residual muscles still cross joints in the residual limb). More research is needed to quantify the extent and rate of muscle degeneration and identify approaches to prevent or reduce degeneration.