Experimental study of muscle reattachment following surgical detachment

Abstract

The process of muscle reattachment was studied in rhesus monkeys using electromyographic and histologic techniques. The attachments of the temporal muscle were exposed on both sides and the muscle was detached from its origin on the right side in ten rhesus monkeys. EMG activity was recorded by fine wires placed intramuscularly within the anterior, middle, and posterior parts of the muscles before and after detachment. The control EMG activity recorded in the attached muscle showed a wide range of values, and there were no clear trends. Following detachment the range of values was also wide, and the differences in activity between the detached muscle and the contralateral attached muscle were not outside the range of difference normally observed between right and left sides. EMG activity was greater before detachment in 31.2% of the recordings and was greater after detachment in 29.4% of the recordings. Biopsies of bone and muscle were taken from normal attachment sites on the left sides and also from the right sides following detachment at one, two, three, four, six, and eight weeks and examined by light microscopy. New bone spicules were seen developing from the surface of the bone after two weeks that were oriented in the direction of the muscle fibers. The reattachment process is one in which new bone is formed on the surface of the bone and develops toward the end of the muscle to envelop the reorganizing tendon. Bone formation occurring on the surface of bones at the ends of muscles is not dependent on tension or viscoelastic properties of the muscle.