Arm Adductor with arm Abduction in rotator cuff tear patients vs. healthy - Design of a new measuring instrument

作者：de Witte P B^*; van der Zwaal P; Visch W; Schut J; Nagels J; Nelissen R G H H; de Groot J H

来源：Human Movement Science, 2012, 31(2): 461-471.

DOI：10.1016/j.humov.2011.08.007

• Rotator cuff tears
• Electromyography
• Activation Ratio
• Diagnostic measure
• Adductor co-activation

The incidence of (a)symptomatic rotator cuff tears is high, but etiologic mechanisms are unclear and treatment outcomes vary. A practical tool providing objective outcome measures and insight into etiology and potential patient subgroups is desirable. Symptomatic cuff tears coincide with humerus cranialization. Adductor co-activation during active arm abduction has been reported to reduce subacromial narrowing and pain in cuff patients. We present an easy-to-use method to evaluate adductor co-activation. Twenty healthy controls and twenty full-thickness cuff tear patients exerted EMG-recorded isometric arm abduction and adduction tasks. Ab-and adductor EMG%26apos;s were expressed using the %26quot;Activation Ratio (AR)%26quot; (-1 %26lt;= AR %26lt;= 1), where lower values express more co-activation. Mean control AR%26apos;s ranged from .7 to .9 with moderate to good test-retest reliability (ICC: .60-.74). Patients showed significantly more adductor co-activation during abduction, with adductor AR%26apos;s ranging between .3 (teres major) and .5 (latissimus dorsi). In conclusion, the introduced method discriminates symptomatic cuff tear patients from healthy controls, quantifies adductor co-activation in an interpretable measure, and provides the opportunity to study correlations between muscle activation and humerus cranialization in a straightforward manner. It has potential as an objective outcome measure, for distinguishing symptomatic from asymptomatic cuff tears and as a tool for surgical or therapeutic decision-making.

• 出版日期2012-4