This narrative review presents the Stanmore classification of shoulder instability. It frames instability as a continuum across three polar types defined by structural versus non-structural causes. It then maps each type to surgical or conservative management and outlines a staged rehabilitation framework.
The core decision rule: before you consider surgery for instability, ask whether the cause is structural, non-structural, or both. The Stanmore classification exists precisely because a shoulder can sit anywhere on the continuum, and treating a muscle-patterning problem with a labral repair fails predictably.
When you see a young patient with a clear traumatic event, positive apprehension, and cuff weakness (type I), high recurrence rates justify surgical stabilisation. When you see insidious onset, party-tricking, painless dislocations, or posterior instability with abnormal muscle activation (type III), surgery is contraindicated. Correct the patterning and core stability first.
The testable pearl: type II structural surgery succeeds only when abnormal muscle activation is corrected preoperatively. Ongoing aberrant firing of latissimus and pectoralis major will pull the head off the glenoid and destroy the repair. This review is a framework, not high-level evidence, and the 45% patterning prevalence reflects a tertiary referral population.
This narrative review presents the Stanmore classification of shoulder instability. It frames instability as a continuum across three polar types defined by structural versus non-structural causes. It then maps each type to surgical or conservative management and outlines a staged rehabilitation framework.
The core decision rule: before you consider surgery for instability, ask whether the cause is structural, non-structural, or both. The Stanmore classification exists precisely because a shoulder can sit anywhere on the continuum, and treating a muscle-patterning problem with a labral repair fails predictably.
When you see a young patient with a clear traumatic event, positive apprehension, and cuff weakness (type I), high recurrence rates justify surgical stabilisation. When you see insidious onset, party-tricking, painless dislocations, or posterior instability with abnormal muscle activation (type III), surgery is contraindicated. Correct the patterning and core stability first.
The testable pearl: type II structural surgery succeeds only when abnormal muscle activation is corrected preoperatively. Ongoing aberrant firing of latissimus and pectoralis major will pull the head off the glenoid and destroy the repair. This review is a framework, not high-level evidence, and the 45% patterning prevalence reflects a tertiary referral population.