Pre-operative score predicting recurrence risk after shoulder stabilization
The Instability Severity Index Score (ISIS) is a preoperative scoring system, scored out of 10, developed by Balg and Boileau to estimate the risk of recurrent instability after arthroscopic Bankart repair for anterior shoulder instability. It combines clinical factors (age at surgery, competitive or contact/overhead sport participation, shoulder hyperlaxity) with radiographic findings (glenoid bone loss and Hill-Sachs lesion visibility on external rotation views) into a single composite number.
It gives surgeons a structured way to have the soft-tissue-versus-bony-procedure conversation with patients before committing to a surgical plan, rather than relying on gestalt. A high score flags a patient at meaningfully greater risk of recurrence with isolated arthroscopic Bankart repair, prompting consideration of a bone block procedure such as Latarjet instead, which changes rehab timelines, precautions, and patient counselling from the outset.
Each component is scored from history, examination and imaging: age at surgery, level and type of sport, degree of shoulder laxity on exam, and presence of a Hill-Sachs lesion or glenoid bone loss on standard radiographs or CT. The points are summed preoperatively, with scores above a threshold (originally proposed around 6 out of 10) traditionally used to favour Latarjet over arthroscopic repair alone.
The exact cut-off for switching procedures is not universally agreed, and the score was derived and validated on specific surgical cohorts, so its predictive accuracy varies across populations and has been questioned in more recent series. It should inform, not replace, clinical judgement and shared decision-making, and it does not capture every relevant variable such as precise bone loss quantification by 3D CT, which many now consider more directly in surgical planning.
This guide was auto-drafted and is pending editorial review.