[Roentgenological measurement of the cervical vertebral bodies in ossification of the posterior longitudinal ligament (OPLL) and cervical spondylosis (CS) (author's transl)].

Many studies of the pathogenesis of ossification of posterior longitudinal ligaments (OPLL) have been reported, and both general and local factors have been pointed out. In case a longitudinal ligament is affected by both the general and local OPLL factors for many years, the shape and size of the cervical vertebral bodies and the arrangement of the cervical spinal column might be affected. The relation between OPLL and disc degeneration, the morphology of the facet joint and the change of longitudinal ligament tension has been reported by many authors. But the relation between OPLL and the shape, size and arrangement of cervical vertebral bodies has not been reported. We selected X-ray films of the lateral view of cervical spines which had been taken at our hospital since 1975. The subjects consisted of 190 cases in Group I and 189 cases in Group II. Half of Group I had OPLL, of which 71 were males and 24 females. The other half of Group I was composed of 95 cases (CS) of cervical spondylosis of the same sex and age distribution. Group II comprised 189 cases, all males aged 49 yrs. Of them, 41 were OPLL cases, 102 CS, and 46 normal subjects. The X-ray films of Group II were taken during medical examinations. The height, antero-posterior diameter of the cervical vertebral bodies and the antero-posterior diameter of the cervical spinal canals were measured and examined for kyphosis between the two neighbouring cervical vertebral bodies, disc space narrowing and Barsony ossification. The height and antero-posterior diameter of the cervical vertebral bodies were compared among the following groups. 1) the 3 groups divided according to age (-49,50-59,60-75 yrs.), 2) segmental type with non-segmental type, 3) OPLL only at C3 and C4 with OPLL only at C5, C6, and C7. The results were as follows: The cervical vertebral bodies of OPLL were taller and wider than those of CS. Cervical vertebral bodies of the older group were shorter and wider than those of the younger groups in both OPLL and CS. THe relative height (C3 = I) of OPLL group was very close to Normal group. The cervical vertebral bodies of non-segmental type were taller but not wider than those of segmental type of OPLL group. The C3 and C4 vertebral bodies with OPLL only at C3 and C4 were taller, but not wider than those with OPLL only at C5, C6 and C7. The antero-posterior diameter of cervical spinal canal of OPLL was narrower than CS group. The above data indicate the following: 1) With advance in age, cervical vertebral bodies become lower and wider. 2) The cervical vertebral body of OPLL is taller and wider than that of CS. 3) The level of OPLL and the type of OPLL have a relation to the height of cervical vertebral body. 4) The cervical vertebral bodies which have OPLL are wider than non-OPLL. But the level and the type of OPLL have no relation with the A-P diameter of the cervical vertebral body.