THE INSTABILITY SEVERITY INDEX SCORE (ISIS SCORE): A RATIONAL APPROACH FOR PATIENT SELECTION IN ARTHROSCOPIC BANKART REPAIR

Abstract

Recurrence represents the leading complication of arthroscopic anterior shoulder stabilization. Even with modern suture anchor techniques, a recurrence rate of between 5 to 20% persists; emphasizing that arthroscopic Bankart repair cannot apply to all patients and selection must be done. Numerous prognostic factors have already been reported, but strict observance would eliminate almost all patients from arthroscopic Bankart repair. We hypothesised that clinical and radiological risk factors could be present and identifiable in the normal outpatient visit, and they could be integrated into a severity score

A case-control study was undertaken, comparing patients identified as failures after arthroscopic Bankart repair (i.e, recurrent instability) with those who had a successful result (i.e., no recurrence). Recurrence was defined as any new episode of dislocation or any subjective complains of subluxation. During a four-year period one hundred and thirty-one consecutive patients with recurrent anterior shoulder instability, with or without shoulder hyperlaxity, were operated by the senior shoulder surgeon with an arthroscopic suture anchor technique and followed for a minimum of two years. Patients were excluded if concomitant pathology, including multidirectional instability, were present. Bony lesions were not excluded. A complete pre and postoperative questionnaire, physical exam, and anteroposterior x-ray were recorded. Mean follow-up was 31.2 months (range, twenty-four to fifty-two months).

Nineteen patients had a recurrent anterior instability (14.5%). Preoperative evaluation demonstrated that age below twenty years old, involvement in athletic competition, participation in contact or forced-overhead sports, presence of shoulder hyperlaxity, Hill-Sachs lesion visible on AP external X-ray, and loss of inferior glenoid sclerotic contour on AP x-ray were all factors related to increased recurrence. These factors were integrated in an Instability Severity Index Score and tested retrospectively on the same population. Patients with a score of six or less had a recurrence risk of 10% and those over six had a recurrence risk of 70% (p< 0.001).

This study proved that a simple scoring system based on factors of a preoperative questionnaire, physical exam, and anteroposterior x-ray can help the surgeon to select patients who would benefit from arthroscopic stabilization with suture anchors and those for whom an open surgery, like the Latarjet procedure, is a better option.