Association Between Manual Loading and Newly Developed Carpal Tunnel Syndrome in Subjects With Physical Disabilities: A Follow-Up Study

Objective: To identify the association between body composition and newly developed carpal tunnel syndrome (CTS) and to search for the best probabilistic cutoff value of associated factors to predict subjects with physical disabilities developing new CTS. Design: Longitudinal. Setting: University-affiliated medical center. Participants: Subjects with physical disabilities (N=47; mean age ± SD, 42.1±7.7y). Interventions: Not applicable. Main Outcome Measures: Median and ulnar sensory nerve conduction velocity (SNCV) were measured at the initial and follow-up tests (interval >2y). Total and regional body composition were measured with dual-energy x-ray absorptiometry at the initial test. Leg lean tissue percentage was calculated to delineate each participant's manual loading degree during locomotion. Leg lean tissue percentage is the lean tissue mass of both legs divided by body weight. Results: Based on median SNCV changes, we divided all participants into 3 groups: subjects with bilateral CTS (median SNCV value <45m/s plus a normative ulnar SNCV value >37.8m/s) in the initial test (n=10), subjects with newly developed CTS in the follow-up test (n=8), and subjects without additional CTS in the follow-up test (n=27). Eight of 35 subjects not having bilateral CTS initially developed new CTS (8.8% per year; mean follow-up period, 2.6y). Leg lean tissue percentage was associated with the probability of newly developed CTS (adjusted odds ratio, .64; P<.05). Subjects with a leg lean tissue percentage >12% were less likely to have developed new CTS at the follow-up test (sensitivity, .75; specificity, .85; area under the curve, .88; P<.005). Conclusions: Leg lean tissue percentage may be useful for early identification of developing new CTS in subjects with physical disabilities. Therefore, a preventive program for those subjects at risk can start early.