The role of exercise in the conservative treatment of the anterior shoulder dislocation

Summary

Anterior shoulder dislocation is a common type of injury, which occurs relatively frequently both during sport and normal everyday activities. A shoulder dislocation is a displacement of the humeral head that causes injury to all capsuloligamentous structures. Consequently, the main clinical sign of shoulder dislocation is functional instability and rehabilitation therefore aims at enhancing the dynamic muscular and proprioceptive restraints to shoulder instability. Conservative treatment of the unstable shoulder has long been discussed emphasizing the importance of exercise. Therefore, the aim of this article is to present an effective exercise-based rehabilitation plan for the non-operative management of anterior shoulder dislocation, according to current knowledge and existing literature.

Introduction

The shoulder joint complex exhibits greater mobility than any other joint in the human body and consequently stability is sacrificed for mobility (Cailliet, 1981). Therefore, due to this inherent instability, the glenohumeral joint has the highest frequency of dislocations, with a 1–2% occurrence rate in the general population and a 7% in athletes. Among shoulder dislocations, the anterior is the most common one, with a 96–98% occurrence rate (Hayes et al., 2002). Anterior shoulder dislocation may occur from a fall onto an elevated outstretched arm or after direct force application to the posterior aspect of the humeral head, but the most common mechanism is excessive or forced external rotation and abduction of the humerus (Liu and Henry, 1996; Hulstyn and Fadale, 1997; Hayes et al., 2002).

A dislocation is a displacement of the humeral head from its normal position in the glenoid fossa leading to separation of the articular surfaces and consequent injury to all capsuloligamentous structures, as they all work in an interconnected fashion. That means that any translation to one direction requires an amount of injury to the static stabilizers of both the unilateral and contra-lateral side. Therefore, for anterior dislocation to occur there has to be a disruption to the posterior capsular structures, meaning that posterior laxity is a component of the pathomechanics of anterior instability. This is referred to as the “circle concept”, a concept on which rehabilitation is based (Nevasier et al., 1988).

Moreover, anterior shoulder dislocation results in anterior instability, due to loss in the normal synchronization of neuromuscular firing patterns and fatigue of the muscles controlling the motion of the humerus and scapula. Therefore, rehabilitation is focused on re-establishing neuromuscular coordination and proprioception, along with muscle strength and endurance (Davies and Dickoff-Hoffman, 1993; Kvitne and Jobe, 1993; Pollock and Bigliani, 1993; Lephart et al., 1997).