Low back pain recurrence in occupational environments.

STUDY DESIGN: Prospective assessment of return to work after low back pain. OBJECTIVE: To determine which factors or combination of factors best predict recurrence of low back pain (defined 4 different ways) when returning to full-duty work. SUMMARY OF BACKGROUND DATA: Recurrent back pain is one of the more costly health problems facing industry today. Few systematic evaluations of the various factors suspected of exacerbating low back pain have been reported in the literature. METHODS: A total of 206 workers who reported low back pain were evaluated as they returned to full-duty work. Five types of assessments were performed including: 1) a low back kinematic functional assessments, 2) evaluation of job physical demands, 3) psychosocial assessment of the job environment, 4) self-reported impairment including perception of symptoms and psychological measures, and 5) personal (individual) factors. One year after return to full duty workers were interviewed to assess who had a recurrence of low back pain according to 4 different definitions of low back pain (symptom reports, medical visits, self-reported lost days, and employer-reported lost days due to back pain). Multiple logistic regression models were developed to assess the best combinations of predictors. RESULTS: The most liberal definition of recurrence, recurrent symptoms, had a significantly greater recurrence rate at 58% than all other outcome measures (P = 0.0001). The medical visit recurrence rate of 36% was significantly greater than the more conservative lost time measures (P = 0.0001). The recurrence rate for self-reported lost time was 15%, whereas the more conservative employer confirmed lost time measure was significantly lower at 10% (P = 0.0077). Multivariate predictive models associated with the various recurrence definitions yielded sensitivities varying between 78% and 80% and specificity between 73% and 80%. CONCLUSION: Recurrence is greatly dependent on how one defines recurrence with symptom reporting yielding 5.5 times as many recurrences compared with employer confirmed lost time. In general, more quantitative measures of worker musculoskeletal function yielded the best predictions of recurrence when predicting the more restrictive definitions of recurrence (employer confirmed lost time).

Grip force and muscle activity differences due to glove type.

The purpose of this study was to investigate the effects of different types and sizes of gloves on external grip force and muscle activity. Twenty-one male and seven female volunteers served as subjects. Each subject performed two maximum voluntary grip contractions while wearing each of the 10 glove types. Results indicated significant differences in the effects of different glove types on the peak force, ratio of peak force to normalized flexor muscle EMG activity, and the ratio of peak force to coactivity.