1. A study of the late results of 343 soundly united tibial shaft fractures was carried out. Limitation of ankle and/or foot movement occurred in twenty-one patients (6 per cent) and was found to be the most important cause of disability. Knee stiffness (2·3 per cent of cases) and shortening of up to three-quarters of an inch (5·5 per cent of cases) caused little functional impairment.

2. Stiffness of the foot and ankle was correlated with the severity of injury, occurring in 1 per cent of minor, 5 per cent of moderate and 22 per cent of major injuries.

3. One-third of the patients with limitation of foot and ankle movement had clinical evidence of ischaemic contracture.

4. It is argued that, in the absence of direct injury to the joint, persistent joint stiffness is caused by replacement fibrosis of soft tissues. This may result either from direct tissue injury or from associated vascular damage.

1 . A series of 343 tibial shaft fractures proceeding to sound union in adults, and 192 fractures in children, was studied. Groups of fractures differing from each other only in the one particular variable under consideration were compared.

2. The severity of the injury (as assessed by the degree of displacement, of comminution and of compound wounding) was found to be an important determinant of speed of fracture union and of incidence of delayed and non-union. A simple classification of severity of injury is described.

3. Distraction delayed healing. Traction which avoided distraction had no effect on the rate of union of fractures of moderate severity compared with cases of similar severity of injury treated by immobilisation only. Major fractures subjected to traction did take longer to unite on the average, but there was no increase in the incidence of delayed or non-union.