Posteroinferior shoulder instability: clinical outcome of arthroscopic stabilization in 32 shoulders and...

Posterior shoulder instability is rare, appears in varying clinical patterns and can be the main symptom in patients with instability in more than one direction. The purpose was to analyze and categorize our patients and to report on the results of operative treatment by arthroscopy.

A consecutive series of 32 shoulders in 31 patients from a 7-year period was chosen for retrospective clinical evaluation with VAS for pain, Rowe Score, Constant Score and Simple Shoulder Test. Follow-up rate was 100 %, the mean FU period was 28 months (range 13-58). Allocation based on clinical and intraoperative criteria resulted in the 4 groups A to D characterized by an increasing traumatic impact. Patients received a posterior Bankart repair with bone anchors in 21 or capsular plication to the intact labrum in 11 cases.

The clinical outcome scores were generally good and all showed a trend towards better results from A to D, but without significance. Pain on VAS pre- and postoperatively showed a significant (p < 0.0001) overall decline from 7.4 to 1.8. The Rowe Score increased significantly (p < 0.0001) from a mean value of 41.4 to 89.5 points. Three patients were reoperated and satisfied, four patients (12.5 %) not satisfied at follow-up. The drive-through sign was significantly (p = 0.003) more distinct in the less traumatic groups A and B than groups C and D. Subgroup allocation resulted in the following distribution: 7 patients qualified for group A (PPM = predominantly posterior multidirectional), 13 for B (RPS = recurrent posterior subluxation), 7 for C (unidirectional) and 5 patients for group D (bi-directional). Graphic display of labral lesions, called "labral mapping", revealed typical patterns for the groups.

In patients with posteroinferior shoulder instability, good results can be obtained with the arthroscopic treatment of all identified pathologies. Categorization into one of four subgroups might be a valuable tool regarding the choice of the operative treatment options.