FUNCTIONAL-EVALUATION AT THE MEDIAL GASTROCNEMIUS DONOR SITE IN RATS

The transfer of a skeletal muscle from a donor to a recipient site cre ates an initial deficit in the structure and function of the muscle gr oup from which it originates, Removal of the donor muscle induces hype rtrophy of the remaining synergistic muscles, which compensate for par t of the deficit at the donor site. The medial gastrocnemius (MGN) mus cle is a frequently utilized donor muscle. Compared with the mass and force production of the control four-muscle plantar flexor group in ra ts, removal of the MGN muscle creates an initial deficit of similar to 36 percent. At 60, 90, and 120 days after removal of the MGN muscle, the degree of compensation of the remaining three-muscle plantar flexo r group (lateral gastrocnemius, soleus, and plantaris muscles) was eva luated. The mass of the three-muscle group increased 13 percent over t he time course studied, but was still 28 percent less than the mass of the control four-muscle group. Similarly, the maximum force of the th ree-muscle group increased 27 percent, but was 21 percent lower than t he control four-muscle group. The authors propose a model that illustr ates the function restored at a donor site in terms of the percentage of the total muscle group comprised by the donor muscle and the abilit y of the remaining muscle group to compensate for its removal.