1. Posterior dislocation of the shoulder is an infrequent injury. It may result from trauma or from convulsive seizure.
2. Because of the infrequency of this injury, and because of the failure to obtain both anteroposterior and lateral (axillary) roentgenograms of the shoulder joint, the dislocation is frequently unrecognized for a long period of time.
3. Prompt recognition and treatment of posterior dislocation of the shoulder by closed manipulation yield excellent results.
4. Even with early prompt reduction, however, the replacement is unstable and there is great danger of spontaneous redislocation.
5. The danger of redislocation can be avoided by the simple expedient of transfixing the reduced humeral head to the acromion process with cruciate wires. This does not require an open operation.
6. Failure of early recognition necessitates open operative intervention. The results of late treatment are poor.