[An epidemiological study on the ossification of the anterior longitudinal ligament of the spine]

An epidemiological study was carried out in connection with the multiphasic screening examination of 1,057 people (442 men and 615 women) in the village of Yachiho. The purpose of this study was to define the etiology of OALL (ossification of the anterior longitudinal ligament) and disc narrowing. The prevalence of disc narrowing increased with age, but OALL was not correlated with aging. OALL was found more frequently in men, but disc narrowing showed no difference between each sexes. The body height and weight-height index were higher in the OALL cases. The body height shrinkage by aging was greater in the patients with disc narrowing cases. The index of thoracic kyphosis was higher in the OALL cases than in the patients with disc narrowing ones. OALL was associated with ossification of the other ligaments of the spine, but disc narrowing was not. This study suggests that despite some similarities, OALL is etiologically different from disc narrowing.