OSSIFICATION OF THE POSTERIOR LONGITUDINAL LIGAMENT OF THE CERVICAL SPINE: C.T. EVALUATION

From 1985 to 1987, we had 69 cases of ossification of the posterior longitudinal ligament (OPLL) found in the 120 patients with cervical myelopathy or radiculopathy in our orthopedic and neurological clinics. All the cases were demonstrated with computed tomography routinely followed cervical myelography. Among the 69 cases, there were 54 cases of male (78.2%) and 15 cases of female (21.8%), the range of age was from 25 to 70, its average age was 47.5. We divided the OPLL into segmental and non-segmental types as Dr. Hirabayashi described in 1981, among the 69 cases, there were 53 cases (76.8%) of segmental and non-segmental in 16 cases {23.2%). The number of segments were from 1 to 5. The most common multiple segments were two (27 cases) and four (19 cases) segments. The total segments in these 69 cases were 189 in number, and the longest was 32 mm, the shortest 2 mm in length. The locations of OPLL in the cervical spine were from C2 to C7. The most comon sites were C3, C4, and C5 (totally in 127 segments, 67.2%). We classified the length of OPLL into 2 mm to 5 mm (65 segments), 6 mm to 10 mm (89 segments), 11 to 20 mm (33 segments), 21 m to 30 mm (1 segment), and 31 mm to 40 mm (1 segment). The diagnosis, morphology, pathology, and pathophysiology of the OPLL are discussed in the texts.