Purpose: The aim of the present study was to analyse and compare the clinical and radiological results after open posterior bone block procedure at long- (LT) and short-term (ST) follow-up. The hypothesis was that placement of a bone block at the posterior glenoid rim in a technique of extending the glenoid surface will create permanent joint stability even in cases with hyperlaxity without a clinically relevant loss of motion or increase in osteoarthritis.
Methods: Fifteen consecutive shoulders with recurrent posterior dislocation were evaluated clinically and radiologically. The Rowe score, Western Ontario Shoulder Index, Walch-Duplay score and the Constant-Murley score were used for clinical evaluation. The patients were categorized according to their follow-up period as either ST follow-up (min 12 months) or LT follow-up (min 42 months).
Results: The clinical results showed no significant difference between ST (9) and LT (6) with good to very good overall results in the subjective as well as the objective scores (CS, RS, WDS). At LT, most patients felt mild to minor pain under strain. The difference in pain between the groups was not significant. Active ranges of motion and strength assessments were normal in all cases. In one case, recurrent dislocations occurred after bone graft resorption 6 months post-operatively. Only one patient presented mild osteoarthritis, without further progress at follow-up.
Conclusion: The open posterior bone block procedure can be a successful treatment option for recurrent posterior shoulder instability at ST and LT follow-up. This series showed a low rate of recurrent dislocations without development or progression of osteoarthritis. Since soft tissue procedures do not always provide satisfying results, the posterior bone block augmentation presents a reliable technique for the treatment of symptomatic posterior instability.
Level of evidence: Case Series, Treatment Study, Level IV.
Keywords: Hyperlaxity; Osteoarthritis; Posterior bone block; Posterior shoulder instability.