Computed tomographic evaluation on ossification of posterior longitudinal ligament and ligamentum flavum ofspine

ABSTRACT

Ossification and calcification of the spinal ligaments frequently cause pressure upon the spinal cord andnerve roots. Authors reviewed 150 cases of C-spine CT, 80 cases of T-spine CT, and 725 cases of L-spine CT whichwere carried out a Pusan Natina University Hospital for 2 years from May 1983 to May 1985. We analysed 34 caseswhich showed ossification of posterior longitudinal ligament (OPLL) and ligamentum flavum (OLF) of these 955cases. The results are follows 1. The male ot female ratio of spinal ligamentous ossification was 268. The 5thdecade group (24.41%) was the most prevalent age group. 4th decade(26.4%), 6th decade(23.52%), 7th decade(11.76),3rd decade (8.8%), and 8th decade(2.94%) in that order. 2. Of 955 cases of spine CT, the incidence of OPLL was 25cases(21.51%) and that of OLF was 10 ases(1.05%). 3. Regional incidence of spinal ligamentous ossification was asfollows. 1) In case of OPLL, cervical area was 19/150(12.67%) and lumbar area was 6/725 (0.83%). 2) In cases ofOLF, Thoracic area was 3/80(3.75%) and lumbar area was 8/725(1.10%). 4. The most frequent length of OPLL was 4body length (32%) and the most frequent locations are C4 and C5(68%). The types fo OPLL were 15 cases(60%) ofsegmental type, 8 cases(32%) of continuous type, and 2 cases(8%) of mixed type in that order. All segmental typeswere degree 1 or 2 and most continuous and mixed type (80%) were degree 2 or 3 dural sac effect. 5. The number ofinvolved interlaminar spaces in OLF was 1 to 5 interspaces and most of OLF were found at low thoracic and lumbararea. 6. There could be noted high correlation between the spinal ligamentous ossification and degenerative discdisease, The incidence of associated disc disease was 18/25(72%) in OPLL and 8/10(80%) in OLF.