Intraoperative measurement of force-length relationship of human forearm muscle

The specific relationship between force and length is one of the most important characteristics of vertebrate muscle. The only accurate method to measure the force-length characteristics is to generate a set of isometric force-time plots at different muscle lengths. In humans, such force-length characteristics mostly are based on indirect measurements that have their limitations. A method of direct, in vivo measurement of force-length characteristics of the human flexor carpi ulnaris muscle using relatively simple equipment during transposition surgery is presented. The method is proven reproducible, with an overall estimated error of 2.8%.