Modified Kouvalchouk technique for recurrent posterior instability of the shoulder: A retrospective multicenter review of 31 cases with an average follow-up of 5 years.

Background: Surgical treatment of recurrent posterior shoulder instability gives good results in cases of isolated posterior labral lesion and relies on arthroscopic capsulo-labral repair. In cases of associated posterior glenoid bony lesions or for revision surgery, iliac crest bone block procedures seem to yield good short-term results, but there might be a concern for long-term results with resorption of the bone block, recurrence, and late arthritis. The Kouvalchouk technique, described in 1993, is using a bone block harvested from the posterior acromion and pedicled to a band of posterior deltoid muscle with presumed sling and vascularization effects. Methods: The primary objective of the study was to assess the mid-term results of a slightly modified Kouvalchouk procedure (open or arthroscopic-assisted) for recurrent posterior shoulder instability. The secondary objectives were to describe the results in subgroups determined by the origin of the instability (traumatic or nontraumatic), surgical history (primary surgery or revision surgery), or surgical technique (open or arthroscopic-assisted surgery) and to evaluate the bone healing of the bone block, its position on the glenoid in the axial and sagittal planes, and the influence of bone loss and glenoid version on pre-operative and post-operative clinical data. Results: Thirty-one procedures were followed over an average period of 4.8 years, and at the last evaluation, 77% of shoulders were stable. All bone blocks were healed. The stability rate was higher in cases of post-traumatic instability (87% vs. 66% for nontraumatic cases). Similarly, Walch-Duplay scores and patient satisfaction were better in traumatic cases (80 vs. 57 and 81% of satisfied patients vs. 40%, respectively). Previous surgery was an unfavorable condition regarding clinical results. As for clinical results or bone block positioning, arthroscopic assistance did not prove better than open surgery.Revision surgery was mostly related to recurrence and was more frequent in atraumatic cases or in previously operated patients. There were as many removals of screws for pain reasons in traumatic and atraumatic cases. Higher glenoid retroversion was associated with lower pre-operative Walch-Duplay and Rowe scores. Glenoid version lower than - 10° was associated with a higher Walch-Duplay postoperative score. Glenoid bone loss had no influence on clinical results. Conclusion: The modified Kouvalchouk procedure provides good results in the stabilization of recurrent posterior unstable shoulders in traumatic cases and patients without previous surgery, with the advantage of local harvesting of a bone block and a potential sling effect.