No difference in outcomes of surgical treatment for traumatic and atraumatic posterior shoulder instability.

Background: Posterior shoulder instability is a rare pathology and accounts for 2-10% of all shoulder instabilities. The purpose of this study was to compare pain and functional scores following surgical treatment of traumatic and atraumatic PSI.

Hypothesis: The authors hypothesize that patients with traumatic PSI are at greater risks of residual pain and recurrent subluxation.

Material And Methods: The records of 150 patients operated for PSI between 2000 and 2015 at 10 different centers were analysed. Inclusion criteria were symptomatic PSI (subluxation and/or pain) with radiographic signs of posterior glenoid erosion or fracture, posterior labral tears, or reverse Hill Sachs lesions. One hundred and seventeen patients were eligible, of which 84% presented symptoms of subluxation and/or dislocation, and 16% were painful without clinical symptoms of subluxation and/or dislocation. Patients were evaluated at 48±33months (range: 12-159) using the Constant, Walch-Duplay and Rowe scores, with pain on Visual Analogic Scale (pVAS).

Results: Compared to atraumatic PSI, traumatic PSI was more prevalent in men (84.4% vs 61.9%, p=0.031), and tended to have fewer pain symptoms (15.8% vs 23.8%, n.s). Atraumatic PSI was more likely to affect the dominant arm, although the difference was not significant (81.0% vs 59.4%, n.s.). Traumatic PSI did not differ from atraumatic PSI in terms of preoperative lesional characteristics, procedures performed, or postoperative pain and instability. Although these differences were not statistically significant, it is worth noting that traumatic PSI patients experienced more recurrence of instability (15.6% vs 4.8%, p=0.298), and lower pain on VAS (1.5±2.3 vs 2.6±3.0, n.s.) compared to atraumatic PSI.

Discussion: Functional scores did not significantly differ between traumatic and atraumatic PSI after surgery, although traumatic PSI patients tended to have a higher recurrence of instability, while atraumatic PSI patients tended to remain more painful.

Level Of Evidence: IV, retrospective cohort study.