Restoration of superficially damaged flexor tendons in synovial environment. An experimental ultrastructural study in rabbits.

Flexor tendon from the synovial sheath region of rabbits was resected and placed as a free body in a synovial knee joint recess. Structural changes of the surface of the graft caused by the instruments used to handle the tendon during the surgery (jewellers microforceps), was analysed by electron microscopy at various time intervals up to 6 weeks. The superficial coat of amorphous material, i.e. ground substance, on the surface of the tendon was dishevelled by the instruments. The injured areas were crowded with monocytes and macrophages during the first days. An increasing number of fibroblasts and mesothelial-like cells covered the damaged area in less than two weeks. The superficial coat of ground substance was not completely restored until after 3 weeks or more. The results obtained are discussed in relation to functional aspects.