A field survey was made to discover the cases with Ossification of posterior longitudinal ligament in the cervical spine and 37 cases were found among 1431 workers.
Analysis was made to investigate the relation of 37 cases to age, Sex, as well as regional and Occupational environment.
4 cases (1.67%) were recognized in agrarian labourers, 3 cases (2.6%) in forestry labourers, 4 cases (3.92%) in fishermen, 14 cases (2.68%) in School techers and 12 cases (2.66%) in other occupetion.