Effect of carpal tunnel syndrome on grip force coordination on hand tools

• Published in: Ergonomics Vol. 42; no. 4; pp. 550 - 564
• Main Author: LOWE, BRIAN D.
• Format: Journal Article
• Language: English
• Published: London Taylor & Francis Group 01.04.1999; Washington, DC Taylor & Francis; Taylor and Francis; Taylor & Francis LLC
• Subjects: Adult; Analysis of Variance; Biological and medical sciences; Carpal Tunnel Syndrome; Carpal Tunnel Syndrome - physiopathology; Case-Control Studies; Coordination; Cranial nerves. Spinal roots. Peripheral nerves. Autonomic nervous system. Gustation. Olfaction; Cts; Ergonomics; Female; Grip Force; Hand Strength - physiology; Hand Tools; Hands; Humans; Male; Medical sciences; Middle Aged; Motor Skills - physiology; Nervous system (semeiology, syndromes); Neurology; Occupational Health; Overuse injuries; Regression Analysis; Risk Assessment; Human; Carpal tunnel syndrome; Gripping; Nervous system diseases; Compression; Force; Diseases of the osteoarticular system; Hand; Pinching; Muscular coordination; Accuracy; Body movement; Upper limb; Peripheral nerve disease; Tool
• ISSN: 0014-0139; 1366-5847
• DOI: 10.1080/001401399185469

This study investigated coordination of the grip force on and force applied with a hand tool using a precision pinch grip. A simulated hand tool was developed to measure grip force exerted on the tool as a function of the force transmitted from the tool to an external object in a dynamic force matching paradigm. Grip force coordination measures reflected subjects' abilities to modulate grip force in parallel with the tool application force and their abilities to minimize excessive grip force. These measures were calculated for seven subjects with a diagnosis of carpal tunnel syndrome (CTS) and seven age- and gender-matched controls. The absolute magnitude of excessive grip force (safety margin) was unreliable because of the high intrasubject variability in coefficient of friction measurements. Linear regression equations predicting coefficient of friction from pinch force magnitude had low r 2 coefficients of determination and were generally not statistically significant (p > 0.05). Relative comparisons of grip force control showed that individuals with CTS exhibited a statistically significant (p < 0.05) increase in ratio of grip force to application force (54% higher than controls) and a significant (p < 0.05) decrease in modulation of pinch force with application force (12% lower than controls). These results suggest that individuals with CTS lose some ability to coordinate efficiently grip force on hand tools and exert higher grip forces on tools, at equivalent application forces, than controls. This is believed to be a result of tactile sensibility deficits associated with CTS. As a result, workers with CTS may be at increased risk of accelerating the progression of their musculoskeletal disorder.