Study of Hand Function in a Group of Shoe Factory Workers Engaged in Repetitive Work

Background: Work related hand and wrist musculoskeletal disorders are well known. The contributing factors could be repetitive movements, forceful work and awkward posture. It is not known how these movements affect grip or pinch strength and other functional aspects of the hand. Aims: To study a group of shoe factory workers doing repetitive thumb and wrist movements for prevalence of musculoskeletal disorders and consequence on grip and pinch strength, two-point discrimination and perceived disability. Methods: 39 shoe factory workers who put straps into 900 to 1000 pairs of rubber sandals per day and 29 hospital clerks as a control group were evaluated for musculoskeletal disorders, grip and pinch strength, two-point discrimination and perceived disability (by questionnaire). Proportions were compared by chi squared or Fisher Exact test and quantitative outcome by t-test or multiple linear regressions. Results: Common musculoskeletal diseases of thumb/wrist were absent among shoe factory workers as in the clerks. Increased two-point discrimination over thumb (p=0.01, right; p=0.02, left) and a clear trend for reduced pinch strength between thumb and index finger (p=0.06, right; p=0.07, left) were noted compared to clerks after adjusting for years on the job. Perceived disabilities included pain and localised dermal thickening over the thumb. Discussion: No case of carpal tunnel syndrome or hand/wrist tendinitis was detected among workers doing highly repetitive thumb/wrist movement. Pinch strength decreased and two-point discrimination was adversely affected while grip strength remained unaffected. The main perceived disabilities of pain and skin changes over the thumb adversely affected their day-to-day life.