SURGICAL TREATMENT OF POSTERIOR INSTABILITY WITH A POSTERIOR BONE BLOCK

Abstract

Purpose of the study: Posterior shoulder instability is a rare condition. Several surgical treatments have been proposed.

Material and methods: This was a retrospective series of 21 posterior bone block procedures performed between 1984 and 2001 and analyzed with mean follow-up of six years. Fifteen patients (n=16) had experienced one or more episodes of posterior dislocation. Thirteen patients were athletes and five had traumatic subluxation with chronic posterior instability. Voluntary recurrent dislocations were not observed in these patients. Male gender predominated (n=19 men, 1 woman). Mean age at surgery was 24.8 years (range 17–40). The dominant side was involved in 12 patients (57%). The Constant and Duplay scores were noted as were the pre- and postoperative x-ray findings. There were ten glenoid fractures, two glenoid impactions, ten anterior humeral notches. Mean retroversion, measured on the scans (n=17) was 9.6° (range 0–21°).

Results: All patients (n=20) were satisfied or very satisfied. At last follow-up, the mean Constant score was 93.3 (range 80–103) and the mean Duplay score (n=21) 85.6 (40–100); 68.2% of patients (n=15) resumed sports activities at the same level. Failure was noted in three patients, one with recurrent posterior dislocation and two with major apprehension. For two patients, glenohumeral osteoarthritis developed postoperatively.

Discussion: Most of the series in the literature have reported results for patients with recurrent posterior subluxations and not for traumatic posterior dislocation, the much more uncommon entity presented here. The rate of bony lesions was high in our series compared with former series in the literature. These results can be explained by two facts. The first that this was a group of recurrent posterior dislocations and second that the analysis of the osteoarticular lesions was made on plain x-rays and/or CT scans. For the two cases of glenohumeral osteoarthritis which developed postoperatively, the position of the bone block does not appear to be involved.

Conclusion: The posterior bone block remains the treatment of choice for recurrent posterior dislocation. The risk of developing osteoarthritis appears to be low but a longer follow-up would be necessary for confirmation.