Monday, October 5, 2009

Scapular Dyskinesia

Abnormal scapular motion is called scapular dyskinesis. Tennis players with scapular dyskinesia present a smaller subacromial space than non-athletes. Silva RT et al reported in Br J Sports Med (2008 Apr 8) that tennis players with scapular dyskinesia present a smaller subacromial space than control subjects. Additionally, when the shoulder was analyzed dynamically, moving from neutral abduction to 60 degrees of elevation, the tennis players with scapular dyskinesia presented a greater reduction in the subacromial space compared to unaffected athletes.

Hence it seems logical that scapular dyskinesis is one causative factor in over-head athletic injuries. However the causal relationship between scapular dyskenesia & shoulder injuries has not been reported. Moreover reliable and valid clinical methods for detecting scapular dyskinesis are lacking.

Let us discuss more on this issue on this subject & understand what exactly is scapular dyskenesia & how to test it.

Following definitions are taken from Journal of Athletic Training 2009; 44(2):160–164 g by the National Athletic Trainers’ Association, Inc (Philip M et al)

Operational Definitions

The movement that is studied:

Shoulder flexion and frontal-plane abduction (5-repeatations). (see the figure above)

Normal scapulohumeral rhythm: The scapula is stable with minimal motion during the initial 30 to 60 degrees of humerothoracic elevation, then smoothly and continuously rotates upward during elevation and smoothly and continuously rotates downward during humeral lowering. No evidence of winging is present.

Scapular dyskinesis: Either or both of the following motion abnormalities may be present.

Dysrhythmia: The scapula demonstrates premature or excessive elevation or protraction, non-smooth or stuttering motion during arm elevation or lowering, or rapid downward rotation during arm lowering.

Winging: The medial border and/or inferior angle of the scapula are posteriorly displaced away from the posterior thorax.

The Rating Scale for scapular dyskinesia:

Each test movement (flexion and abduction) rated as

a) Normal motion: no evidence of abnormality

b) Subtle abnormality: mild or questionable evidence of abnormality, not consistently present

c) Obvious abnormality: striking, clearly apparent abnormality, evident on at least 3/5 trials (dysrhythmias or winging of 1 in [2.54 cm] or greater displacement of scapula from thorax)

Final rating is based on combined flexion and abduction test movements.

Normal: Both test motions are rated as normal or 1 motion is rated as normal and the other as having subtle abnormality.

Subtle abnormality: Both flexion and abduction are rated as having subtle abnormalities.

Obvious abnormality: Either flexion or abduction is rated as having obvious abnormality.

The relationship of Scapular dyskinesia to that of Shoulder injuries

Source: Journal of Athletic Training 2009;44(2):165–173 g by the National Athletic Trainers’ Association, Inc (Angela R et al)

Angela et al reported that presence of scapular dyskinesis was not related to shoulder symptoms in athletes engaged in overhead sports.

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