The mechanical properties of human flexor tendons in relation to artificial tendons

The continuation of an unacceptable failure rate with tendon repair or grafting procedures, largely due to adhesions, suggested that an artificial flexor tendon could be an attractive alternative. A literature search found no published data of the mechanical properties of fresh human finger flexor tendons, so a study of the strength and extensibility of 153 tendons was carried out. The bone insertion strength of twenty middle finger tendons was also examined. The results showed that an artificial tendon should have a strength of approximately 1500N, and that it should extend 13% at that load, an elongation of 26mm for a tendon 200mm long. The insertion strength was less than a half of the tendon strength. This data will allow an artificial flexor tendon to be designed with sufficient strength and the correct elastic properties to allow its function to integrate reliably with natural tendons in adjacent fingers.