Good functional outcome but high rates of instability recurrence after posterior open-wedge glenoid osteotomy for the treatment of posterior shoulder instability with increased glenoid retroversion at mid-term follow-up.

PURPOSE: To evaluate clinical, functional and radiological mid-term outcomes following posterior open-wedge glenoid osteotomy (POWGO) for the treatment of posterior shoulder instability (PSI) associated with increased glenoid retroversion.

METHODS

Patients who underwent POWGO for the treatment of symptomatic PSI with glenoid retroversion >10° and participated in a previous study assessing short-term outcomes were included after a minimum follow-up of 5 years. Clinical (Rowe score and physical examination) and functional outcomes (Oxford Shoulder Instability Score [OSIS] and visual analogue scale [VAS] for pain) were assessed. Preoperative versus follow-up magnetic resonance imaging (MRI) assessments were compared for changes in posterior humeral head subluxation (PHHS) and progression of osteoarthritis (shoulder osteoarthritis severity [SOAS] score).

RESULTS

Eight patients (nine shoulders) were included 92.0 months (88.0-109.5 months) post-operatively, of which seven patients (eight shoulders) underwent MRI. Shoulder function was good (Rowe score: 80.0 [76.3-91.3], OSIS: 41.0 [31.0-41.5]) and pain levels were low (VAS for pain: 3.0 [1.0-3.0]) at follow-up. Overall, the degree of PHHS did not change between preoperatively and follow-up (p > 0.05). Four shoulders demonstrated PHHS preoperatively, of which two had a centred humeral head at follow-up. Shoulder osteoarthritis progressed significantly (SOAS score: 17.0 [11.0-24.5] to 33.0 [31.0-45.0], p = 0.018). Residual PSI was evident in 75.0% of shoulders.

CONCLUSION

At mid-term follow-up, POWGO for PSI associated with increased glenoid retroversion led to good functional outcomes but failed to reliably restore posterior shoulder stability and prevent osteoarthritis progression.

LEVEL OF EVIDENCE: Level IV.