AIM: The possibility that functional impingement results from muscular imbalance is under discussion. This study investigates whether the disturbance of muscular coordination could be demonstrated as a shift in the balance of FT and ST fibers, since the FT fibers enable a rapid reaction or contraction, and ST fibers enable slow contractions and sustained performance. METHOD: In 37 patients with a supraspinatus syndrome, partial or complete rupture of the rotator cuff, we took biopsies from the supraspinatus and deltoid muscles and did morphometric measurements.< RESULTS: All three groups of patients showed a reduction in size, increased variability and change in frequency of the fiber cross sections. The FT fibers are especially affected. These findings are objectively confirmed by morphometric measurements. CONCLUSION: A disturbance in coordination of the musculature which can bring about functional impingement might be inferred from the above changes. We term this "neuromuscular insufficiency of the rotator cuff". The mechanical factors relating to subacromial impingement probably only have a role in promoting its manifestation by restricting the compensation range of the joint.
AIM: The possibility that functional impingement results from muscular imbalance is under discussion. This study investigates whether the disturbance of muscular coordination could be demonstrated as a shift in the balance of FT and ST fibers, since the FT fibers enable a rapid reaction or contraction, and ST fibers enable slow contractions and sustained performance. METHOD: In 37 patients with a supraspinatus syndrome, partial or complete rupture of the rotator cuff, we took biopsies from the supraspinatus and deltoid muscles and did morphometric measurements.< RESULTS: All three groups of patients showed a reduction in size, increased variability and change in frequency of the fiber cross sections. The FT fibers are especially affected. These findings are objectively confirmed by morphometric measurements. CONCLUSION: A disturbance in coordination of the musculature which can bring about functional impingement might be inferred from the above changes. We term this "neuromuscular insufficiency of the rotator cuff". The mechanical factors relating to subacromial impingement probably only have a role in promoting its manifestation by restricting the compensation range of the joint.