The mechanical factors in tendon repair have been studied and physical principles applied to this unsolved problem. A new technique of tendon repair has been derived and tested in the laboratory. Compared to several well known techniques it has been shown to have three times the tensile strength and to allow one tenth the gap to form between the tendon ends under load. It has been designed not to constrict the blood supply of the tendon and the tests indicate that it will be strong enough to allow early active mobilisation even after inflammation has caused the tendon to soften.

A "six strand" method of tendon repair has been used to treat 36 fingers with flexor tendon lacerations. Following surgery, active mobilisation in a protective splint was begun immediately. 63% of lacerations were in zone 2 and 27% in zone 1. 69% and 100% respectively achieved an excellent or good result using Buck-Gramcko's assessment method. 81% of all the fingers were rated excellent or good.

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Six patients (14%) had scaphoid waist fractures. There were other bony injuries in a further six. In 40 patients there was agreement between the BS and MRI findings. In three cases there was discrepancy between the imaging modalities; in all three MRI was found to be the more sensitive and specific. MRI could become the investigation of choice for this injury.

Active and passive muscle tension is discussed in relation to finger flexor and extensor tendons. Minimising active tension required to produce finger movement is seen as an important part of post-operative finger mobilisation following flexor tendon repair in which active movement is used. It is argued that "minimal active tension" in the flexors is equal to, or just exceeds, the passive tension in the extensors. A method of measuring passive tension in finger tendons has been described. In 24 volunteers, it has been used to determine that if the metacarpo-phalangeal joints are held flexed, there is least "minimal active tension" in the flexor tendons when the wrist is splinted in extension.