SHOULDER INSTABILITY

problem when the abnormal sequencing is not clear. The therapist should always carry out a thorough assessment looking at both the shoulder and the kinetic chain. In the sporting athlete optimal flexibility in the lower limbs and trunk together with dynamic stability of the core musculature and lower limb are essential. This following section assumes that the reader has knowledge of a full shoulder assessment including the assess- ment of local and global stability control but aims to point out clinical clues that can help confirm a patterning problem.

Posture Common findings on observing posture will be a tendency to weight bear away from the problem shoulder. Patients often demonstrate an inability to dissociate the pelvis from the thorax and have difficulty with lateral weight transfer under the affected shoulder without shortening of the trunk. This immediately means that they lack the elongation necessary to ‘release’ their upper limb for active move- ment. In those patients with a latissimus dorsi dominance there may be observable side flexion. Equally in pectoralis domi- nance the patient will often be in a protracted shoulder position and have an observable or palpable increase in resting tone in the pectoralis major. This can apply to anterior or posterior deltoid too. Observation of gait will provide further evidence for interaction between the dif- ferent components of the kinetic chain

Note: Medial rotation of the upper limb and retraction/anterior tilt of the scapula

Latissimus dorsi

and will often confirm a tendency to fix with the dominant muscle reducing shoul- der girdle movement or arm swing on the affected side.

Movement pattern Observation of active movement or the patient’s functional problem movement will demonstrate key factors. In the polar type III patients abnormalities of move- ment pattern are often quite dramatic. A common abnormal pattern is that where the patient initiates movement with excessive medial rotation of the upper limb followed by excessive retraction and anterior tilt of the scapula dramatically (Figures 6 and 7). This can result from pectoralis and latissimus patterning with inhibition of the external rotators and posterior deltoid. In patients where latis- simus dorsi dominates the observer can see a significant ‘drop’ or inferior glide of the humeral head as movement progress- es. This is often associated with subtle side flexion of the trunk (Fig.8).

Patients lack the ability to transfer their weight under the moving shoulder so that latissimus dorsi is unable to release the upper limb due to its attempts to stabilise the trunk. The result is a posterior-inferior pull on the glenohumeral joint. These patterns are often seen in a more subtle form in the muscle patterning subgroup. Commonly latissimus dorsi and pectoralis are inappropriately activated together, however the pattern of abnormal transla- tion/subluxation/dislocation will be deter- mined by which initiates first and most dominantly. Less common patterns are where the anterior or posterior deltoid dominate resulting in anterior or posterior subluxation/dislocation. In some patients abnormal facilitation of the patterning muscles results in a persistent disloca- tion/subluxation where a muscle is permanently activated and the patient is

Figure 6 and 7: Excessive medial rotation of the upper limb followed by excessive retraction and anterior tilt of the scapula

unable to find a strategy to ‘switch the muscle off’. These patients are a particu- larly challenging group.

Palpation There is often a palpable increase in rest- ing tone in the ‘offending’ muscle. We can effectively adapt commonly used tests to allow us to more definitively identify the muscle pattern problem. If the therapist suspects patterning, palpation of the latissimus dorsi as it travels laterally to the inferior angle of the scapula while the patient actively elbow flexes or externally rotates the shoulder, will allow them to feel significant activation compared to the ‘normal’ side. This can be repeated with pectoralis or the deltoid.

Rotator cuff testing Routine testing of the rotator cuff can also give us useful information. For exam- ple, testing of external rotation in neutral – in the presence of latissimus dorsi pat- terning you will often feel the patient ‘fix’ against you as they try and adduct the arm (Fig.9). Similarly they may try and ‘fix’ into protraction/flexion as you add resistance if the pectoral muscles are the culprit. Simple testing of medial rotation strength will often show a pectoralis and/or anterior deltoid problem. Palpation of the humeral head during test-

Patient may side flex trunk in response to resistance

Patient adducts arm in response to resistance

Figure 9: Latissimus dorsi patterning on external rotation

Latissimus dorsi

Patient will often pull down against therapist’s hand during facilitation of the scapula

Figure 8: Side flexion of the trunk with movement of the humeral head

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Figure 10: Scapula assistance test www.sportex.net