Relationship between Shoulder Function and Maximum Reach Envelope
Dewis, Colleen A.
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Background: Reach envelope or volume is the area in which a seated or standing human can reach. The maximum reach envelope (MRE) is performed with the trunk stable and the upper limb fully extended, thus shoulder mobility and function are key determinates. Persons with total rotator cuff tears have reduced range of motion and reach envelope capabilities, particularly with respect to horizontal and vertical motions at the periphery of the reach envelope. Ergonomic accommodations for an individual can be made to allow for potential return to work and assistance with activities of daily living if the limitations are known. Objectives: To compare the MRE and the impact of small handheld loads on this for aged matched and college-aged adults with no history of shoulder injury (asymptomatic participants) and participants with total rotator cuff tears prior to and at several time points following surgical repair. This MRE will be used to define problematic areas of reach for symptomatic participant’s pre and post-surgery to make recommendations for reasonable ergonomic accommodations to assist with activities of daily living and return to work. Methods: Seated dynamic maximum reach envelope data was collected using the Computerized Potentiometric System for Anthropometric Measures (CPSAM) with 3 different handheld load condition (0.0, 0.5 and 1.0 kg) for 3 groups (young asymptomatic, age matched asymptomatic and persons with rotator cuff tears). Additionally anthropometric measures, range of Motions (ROM), strength, Disabilities of the Shoulder and Hand (DASH) and Western Ontario Rotator Cuff Index (WORC) survey data were collected for comparison between groups. Conclusions: There are differences between reach and ROM capabilities of persons with RCT and asymptomatic, with a reduction in range of motion capabilities being reflected in a reduced reach envelope. This difference increases with the addition of hand held load, with the outer boundaries of reach showing the largest reduction. Accommodations for both workplace and activities of daily living (ADL) may be required to allow a person with a rotator cuff injury to maintain functionality, particularly when reaching in across the body and above the head.