Image Quiz

Persisting Pain and Limitation of Motion Following an Injury to the Shoulder (continued)

Answer: Posterior dislocation of the shoulder.

An anteroposterior radiograph of the shoulder revealed a lightbulb sign, and a computed tomography scan showed a locked posterior dislocation of the humeral head with 25% to 30% impaction of the articular surface. A magnetic resonance imaging scan was done to evaluate the capsuloligamentous structures of the joint (Figs. 1-A, 1-B, and 1-C).

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Fig. 1-A
Fig. 1-B
Fig. 1-C
Figs. 1-A, 1-B, and 1-C Preoperative imaging of the shoulder.
Fig. 1-A Conventional anteroposterior radiograph showing the reverse Hills-Sachs lesion (arrows).
Fig. 1-B Computed tomography scan showing the locked posterior dislocation and the reverse Hill-Sachs lesion.
Fig. 1-C Magnetic resonance imaging scan in the transverse plane, with T1-weighted spin-echo sequence (with a repetition time of 600 msec and an echo time of 20 msec), showing the damaged posterior capsule and labrum (arrow) without signs of injury on the anterior capsule.

Discussion

Traumatic posterior dislocation of the shoulder is frequently missed, and treatment is often delayed. Neglected posterior dislocations are difficult to treat, and their clinical outcome is often suboptimal.

Several posterior approaches to the shoulder have been reported in the literature. For our patient, a limited direct posterior anatomic reduction and repair was planned and executed. The posterior deltoid-splitting approach, as described by Wirth et al., was used. The exposure of the posterior capsule was adequate, and the reduction and capsular repair proved to be relatively easy. The reverse Hill-Sachs lesion, which in our patient was 25% to 30% of the articular surface, was left untreated following an intraoperative evaluation of joint stability. Larger defects would probably need bone-grafting.

Our patient fully resumed his activities and regained almost full range of motion. At three years postoperatively, he had no pain and no sign of glenohumeral instability.

Reference

1. Karachalios T, Bargiotas K, Papachristos A, Malizos KN. Reconstruction of a neglected posterior dislocation of the shoulder through a limited posterior deltoid-splitting approach. A case report. J Bone Joint Surg Am. 2005;87:630-4.