This review describes the biological problems faced by those managing primary flexor tendon injuries and explains why these problems still thwart attempts to achieve normal, or near normal, function after this injury, despite a century of surgical effort. It considers the historical background of the early 20(th) century attempts to improve the results and analyses the clinical usefulness of more recent research into tendon core and circumferential suture modification, including the authors' work in this field, and changes in post-operative mobilisation over the last 50 years. More recent manipulation of the sheath to improve results and the future possibility of manipulation of adhesions are discussed. It also discusses other factors, e.g., the patient, the experience of the surgeon, the use of therapists, the timing of repair, complex injuries, injuries in zones other than zone 2, which can have a bearing on the results and considers how these can be modified to avoid an unfavourable outcome.
Keywords: Avoidance unfavourable results; flexor tendon surgery; primary flexor tendon surgery; unfavourable results.