Instability Severity Index Score (ISIS) Calculator

Age at intervention
Degree of sport participation
Type of preoperative sport
Shoulder hyperlaxity
Hyperlaxity is defined by an external rotation of the elbow to the body greater than or equal to 85° and/or an asymmetrical hyper-abduction test of more than 20°.
Notch on x-ray
Search for a Hill-Sachs lesion on a frontal (antero-posterior) radiograph.
Loss of radiological contour of the subchondral bone
Loss of radiological contour of segment C subchondral bone on an AP radiograph in neutral rotation


Score :

Instability Severity Index Score (ISIS) Calculator

• If the ISIS Score > 6 POINTS: indication of LATARJET type screwed abutment.

• If the ISIS Score < 3 POINTS: indication for arthroscopic BANKART

• If 3 < ISIS score < 6 POINTS: risk of recurrence of arthroscopic BANKART > 10%. Need to make an abutment or perform a procedure complementary to the arthroscopic technique.

Instability Severity Index Score and glenohumeral dislocation

Without any possible discussion, anteromedial glenohumeral dislocation is the most common form of traumatic dislocation (95%). Young athletes are the most concerned because of the practice of certain risky sports such as judo, handball, skiing, javelin...

Even if the traumatic mechanism can vary according to the activity being either direct (fall on the stump of the shoulder, posterior shock), or indirect (movement of armed countered, traction on the arm, abduction-external rotation forced), dislocation is frequently encountered in these sports and the nature of the treatment to be implemented often arises.

In order to avoid frequent recurrences, conservative treatment has been abandoned in high-level athletes, but the classic question still remains today of the surgical choice between an "arthroscopic Bankart" (labral reinsertion and capsulo-ligamentary retensioning) or a " Latarjet in the open” (coracoid abutment).

Concerning the Bankart technique, an analysis of the literature has shown that even with the most recent technical advances, the rate of recurrence of instability after arthroscopic stabilization varies between 10 and 30% and we now know that recurrences of instability are linked to the decline and necessarily increase over time.

This is why Balg and Boileau have codified the ISIS Score (Instability Severity Index Score) which, thanks to 6 preoperative prognostic factors, allows to guide the therapeutic indication in favor of one or the other technique. (Bankart vs. Latarget). They realized that the presence of these factors could favor the recurrence of instability in the event of Bankart's intervention, particularly if they are associated.

 These factors are:

 1) age < 20 years.

2) level of sports practice (competition, leisure, or no sport)

3) type of sport practiced: contact, army-counter, or “calm” sport.

4) hyperlaxity of the affected shoulder: anterior hyperlaxity with an external rotation of the elbow to the body >85° or lower hyperlaxity with a hyperabduction test >20° differential between the 2 shoulders.

5) Hill-Sachs bone lesion (notch on the humeral head) on external rotation AP shoulder radiograph.

6) glenoid rim bony lesion on AP radiograph (fractured or blunt rim)