Stanmore Classification of Shoulder Instability

Original Editors - Ammar Suhail

Top Contributors - Ammar Suhail and Christopher Nyunt

Introduction

Shoulder instability is the symptomatic abnormal motion of the glenohumeral joint (GHJ), which can present as pain or a sense of displacement either as a subluxation or a dislocation. The patient usually reports abnormal motions and sense of apprehension while doing Activities of daily living (ADLs). Shoulder being a mobile joint has a high predisposition for Instability.

Classification

The classification suggests that for the symptoms to occur there has to be a disturbance of one or more of the following factors, in isolation or together:

• the capsulolabral complex and its proprioceptive mechanism
• the rotator cuff
• the surface arc or area of contact between the glenoid and humeral head
• the central/peripheral nervous system.

Stanmore classification system proposes three types of shoulder instability recognising the structural and non-structural components and that a continuum exists between pathologies. The concept of instability being caused by a combination of structural (traumatic and atraumatic) and neurological system disturbances has led to the classification of instability as a continuum of pathologies. The system also proposes that direction of instability is not as relevant to effective management as whether the instability is structural, non-structural or both The following are the three different forms of Instabilities according to Jaggi and Lambert, 2010 (Stanmore Classification):

1. Polar Type I (Structural Instability)
2. Polar Type II (Atraumatic Instability)
3. Polar Type III (neurological dysfunctional or muscle patterning)