The impact of rotator cuff tendinopathy on proprioception, measuring force sensation.
BACKGROUND
The impact of rotator cuff tendinopathy and related impingement on proprioception is not well understood. Numerous quantitative and qualitative changes in shoulder muscles have been shown in patients with rotator cuff tendinopathy. These findings suggest that control of force might be affected. This investigation wants to evaluate force sensation, a submodality of proprioception, in patients with rotator cuff tendinopathy.


METHODS
Thirty-six patients with rotator cuff tendinopathy and 30 matched healthy subjects performed force reproduction tests to isometric external and internal rotation to investigate how accurately they could reproduce a fixed target (50% MVC). Relative error, constant error, and force steadiness were calculated to evaluate respectively magnitude of error made during the test, direction of this error (overshoot or undershoot), and fluctuations of produced forces.


RESULTS
Patients significantly overshoot the target (mean, 6.04% of target) while healthy subjects underestimate the target (mean, -5.76% of target). Relative error and force steadiness are similar in patients with rotator cuff tendinopathy and healthy subjects. Force reproduction tests, as executed in this study, were found to be highly reliable (ICC 0.849 and 0.909). Errors were significantly larger during external rotation tests, compared to internal rotation.


CONCLUSIONS
Patients overestimate the target during force reproduction tests. This should be taken into account in the rehabilitation of patients with rotator cuff tendinopathy; however, precision of force sensation and steadiness of force exertion remains unaltered. This might indicate that control of muscle force is preserved.
Department of Physiotherapy and Rehabilitation Sciences, Ghent University, Ghent, Belgium. annelies.maenhout@ugent.be
Annelies G
AG
Maenhout
Tanneke
T
Palmans
Martine
M
De Muynck
Lieven F
LF
De Wilde
Ann M
AM
Cools
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D016022:Case-Control Studies; D004576:Electromyography / Q000379:methods; D005080:Exercise Test / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D010865:Pilot Projects; D011434:Proprioception / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology*; D012016:Reference Values; D017006:Rotator Cuff / Q000503:physiopathology*; D012680:Sensitivity and Specificity; D012684:Sensory Thresholds / Q000502:physiology; D012785:Shoulder Joint / Q000503:physiopathology; D013314:Stress, Mechanical; D052256:Tendinopathy / Q000175:diagnosis*; D055815:Young Adult