Posterior bone block: a reliable method to treat recurrent nonlocked posterior shoulder dislocation with engaging reverse Hill–Sachs lesion

Abstract

Background Posterior shoulder dislocation was first reported in 1839 by Sir Astley Cooper. Hill and Sachs, in 1940, stated that with any dislocation event the soft bone of the humeral head impacts against the harder, sharper edge of the glenoid, leading to an impression fracture of the posterosuperior head in recurrent anterior dislocation. A reverse Hill–Sachs lesion is an impression fracture in the anterosuperior head in recurrent posterior dislocation. In 1952, McLaughlin described his surgical technique to treat an anterior impression fracture of the humerus after recurrent posterior shoulder dislocation. Hypothesis Our hypothesis is to prove that posterior bone block augmentation of the posterior glenoid is a safe and reliable line of treatment in cases of recurrent posterior instability with engaging reverse Hill–Sachs lesion. Patients and methods Between March 2009 and March 2011 five cases were referred to us with chronic recurrent posterior shoulder dislocation with engaging reverse Hill–Sachs lesion. The mean age of the patients was 28 years (range: 20–36 years). There were two left and three right shoulders. All patients were male. All patients were manual workers. All sustained traumatic dislocations through nonathletic accidents. None of the patients had epileptic fits before. Preoperatively, the mean active forward elevation was 140° (range: 130°–150°) and external rotation with the arm at the side was 35° (range: 20°–50°). Preoperative constant score average was 40 points (range: 30–50 points). The mean time interval between injury and surgery was 12 months (range: 8–16 months). All cases had engaging reverse Hill–Sachs lesion. None of the cases had significant posterior glenoid bone loss. All patients were treated with open posterior bone block augmentation of the posterior glenoid harvested from the anterior iliac crest. Results Patients were evaluated at 3, 6, 12, and 24 months. Range of motion was recorded and follow-up radiographs were taken to evaluate graft incorporation. The mean follow-up time for the five patients was 30 months (range: 24–36 months). At 6 months postoperatively, the mean forward elevation was 165° (range: 160°–170°) and external rotation with the arm at the side was 55° (range: 40°–70°). Patients were evaluated postoperatively according to the constant score system (maximum: 100 points). We found a mean postoperative constant score of 87.5 points (range: 80–95 points), a fairly good result considering the nature of bone loss. Conclusion The posterior bone block can successfully restore the stability and function of the shoulder in patients with recurrent posterior dislocations with significant engaging reverse Hill–Sachs lesion in which arthroscopic soft-tissue reconstruction is not a reasonable option. This technique can be used for combined soft tissue and bony defects as well as for revisions after previous soft-tissue reconstructions.