[Neuromuscular failure of the rotator cuff as a contribution to the functional impingement of the shoulder - a muscle biopsy investigation].
OBJECTIVE
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.


METHODS
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.


CONCLUSIONS
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.
Gansen
H-K
HK
Orthopädische Klinik des Marienstifts Arnstadt, Germany.
lrlenbusch
U
U
D000328:Adult; D000368:Aged; D001706:Biopsy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018656:Muscle Fibers, Fast-Twitch / Q000473:pathology*; D018657:Muscle Fibers, Slow-Twitch / Q000473:pathology*; D009468:Neuromuscular Diseases / Q000473:pathology*; D012307:Risk Factors; D017006:Rotator Cuff / Q000473:pathology*; D000070636:Rotator Cuff Injuries; D012422:Rupture, Spontaneous; D019534:Shoulder Impingement Syndrome / Q000473:pathology*