The purpose of study was to define the clinical and epidemiological factors of HNP and to provide the meaningful ources for establishing a prognosis and a rationale for clinical management of occupational low back problem.

This study was performed at eight branch hospitals of Catholic University of Korea and several governmental hospitals f or occupational disorders around the Kyunggi province of Korea since Jan. 1985. We analyzed the several factors about lumbar HNP through comparative study of the hospital admission series of each 200 patients in both occupation- and nonoccupation related, subjected to epidemiologic and clinical investigation, respectively.

1. Mean age of occupational HNP was younger(30.9+/-8.8) than non-occupational HNP(35.2+/-10.5) (p<0.05). 2. The duration of clinical symptom before admission was longer in non-occupational HNP(19.9+/-22.8 Mo.) than in occupational HNP(6.9+/-12.4 Mo.) (p<0.05). 3. The symptomatic attack before admission was more frequent in non-occupational HNP(3.7+1.9) than in occupational HNP(2.5+/-0.9) (p<0.05). 4. There were no significant differences in physical findings between two groups, except for low rate(63%) of straight leg raising test(SLR) limitation in occupational HNP compared to non-occupational HNP(83%) (p<0.05). 5. Even though The main reason for operative intervention was a failure of conservative treatment in both groups(p<0.05), extruded subligamentous type was predominant(50%) in occupational HNP(p<0.05), whereas extruded transligamentous type occupied major portion(67.8%) in non-occupational HNP(p<0.05).

The clinical results were poor in occupational HNP in both conservative and operative management groups, compared to non-occupational HNP(p<0.05) and mean durations admission and re-admission rate was higher in occupational HNP, compared to non-occupational HNP (p<0.05).