Acute Biceps and Supraspinatus Tendon Changes Associated with Wheelchair Propulsion

摘要

Manual wheelchair uses rely on their upper limbs for mobility and activities of daily living. Unfortunately more than half of manual wheelchair users will experience shoulder pain, due in part to repetitive loading during wheelchair propulsion and transfers. While chronic upper extremity pathology has been well documented, no research has investigated acute rotator cuff changes that occur as a result of wheelchair propulsion. Ultrasound is a non-invasive, convenient method to examine soft tissue structures of the shoulder, but tendinosis is rated subjectively by the operator. Here we apply image analysis techniques to quantify tendon size, echogenicity, and greyscale texture. We have developed a standardized protocol, and custom reference marker, to maximize reliability of these measures. Further, content validity was established by relating greyscale-based quantitative ultrasound measures to known risk factors for shoulder pain and pathology including increased age, duration of wheelchair use, and body weight. Quantitative ultrasound measures also correlated to clinically graded tendinosis and discriminated between people with and without symptoms on physical examination. Sixty-seven manual wheelchair users underwent quantitative ultrasound examinations of the biceps and supraspinatus tendons before and after an intense wheelchair propulsion task. Biceps tendon greyscale texture post-propulsion was significantly impacted by clinically graded tendinopathy, duration of wheelchair use, resultant force, and stroke frequency when controlling for pre-propulsion ultrasound image texture. Subjects with tendinopathy or a longer duration of wheelchair use tended to have a darker, less organized tendon microstructure following propulsion likely due to the presence of inflammatory factors or other fluid. In contrast, subjects who used a higher stroke frequency or resultant force showed a brighter, more aligned tendon fibrillar structure due to mechanical loading of the tendon. In a subsample of subjects, we found that increased shoulder forces and moments during propulsion correlated with more severe supraspinatus tendinopathy. These subjects also experienced a larger decrease in supraspinatus tendon width and greyscale variance following the intense propulsion task. Quantitative ultrasound measures describe tendon microstructure and are sensitive to risk factors for shoulder pain and pathology. This technique may help identify the best interventions to reduce an individual's risk of developing upper limb pathology.