1. Five hundred shoulders in a series of 488 patients, with a follow-up study on 313 shoulders (63 per cent), are reviewed relative to prognosis.
2. The study included patients treated over the past twenty years, with a mean follow-up period of 4.8 years.
3. In 38 per cent of the patients the dislocation recurred.
4. Primary shoulder dislocations were found to occur as frequently after forty-five years of age as before forty-five.
5. The incidence of recurrent dislocation of the shoulder was very high in the second decade (92 per cent), but showed marked decrease after age fifty (12 per cent).
6. The age of the patient at the time of the primary shoulder dislocation was the most significant single prognostic factor.
7. Throughout this study, the average age of those patients in whom redislocation did not occur was greater than in those in whom dislocation did recur.
8. Various phases of trauma in relation to dislocations were reviewed. Usually the greater the initial injury, the lower was the incidence of recurrence.
9. Fracture of the shoulder girdle was a complication in 24 per cent. The incidence of fracture of the greater tuberosity was 15 per cent. This complication was accompanied by an appreciable lowering of the incidence of recurrence (7 per cent). The exception was in chip fractures of the anterior glenoid rim.
10. Humeral-head defects were present in 38 per cent of the primary dislocations and in 57 per cent of recurrent dislocations. These were associated with an increase in the incidence of recurrence (82 per cent).
11. From our figures, the incidence of recurrence seemed to be affectd very little by the type and length of immobilization of the shoulder following dislocation. Although a high incidence of recurrence was noted in the group of patients for whom where was no immobilization or for whom there were very short periods of immobilization, long periods of immobilization were not associated with a significant decrease in recurrence.
12. The incidence of recurrent dislocation relative to handedness was not significant.
13. Following primary or initial dislocation, 70 per cent of the dislocations which recurred did so within two years.
14. Following operative procedures for the repair of recurrent shoulder dislocation, 52 per cent recurred within two years after operation.
15. The incidence of posterior dislocation was 2 per cent.
16. The incidence of bilateral dislocation was 2.4 per cent.
17. The incidence of associated nerve injury was 5.4 per cent.
18. The incidence of epileptics with shoulder dislocations was 2 per cent.