Effects of immobilization and continuous passive motion on postoperative muscle atrophy in mature rabbits.

The effects of continuous passive motion and cast immobilization on muscle atrophy were compared 3 weeks after bilateral arthrotomies on 10 mature New Zealand rabbits. The gastrocnemius, rectus femoris and tibialis anterior muscles were excised and weighed, and the dry weights of the gastrocnemius were also determined. The protein concentration and cross-sectional areas of types I and II muscle fibres in the rectus femoris and tibialis anterior muscles were measured. Compared with the results in rabbits treated by cast immobilization, continuous passive motion significantly (p less than 0.05) reduced muscle atrophy as determined from the wet and dry weights of the gastrocnemius muscles, the protein content in the tibialis anterior muscles and the cross-sectional areas of the type II fibres in the rectus femoris muscles.