Ann Rheum Dis: first published as 10.1136/ard.47.1.62 on 1 January 1988. Downloaded from Annals of the Rheumatic Diseases, 1988; 47, 62-64 Computed tomographic demonstration of calcification of the ligamenta flava of the lumbosacral spine in ankylosing spondylitis ELIESER AVRAHAMI,' IRENA WIGLER,2 DORIT STERN,' DAN CASPI,2 AND MICHAEL YARON2 From the Departments of'Radiology and 2Rheumatology, Sourasky Medical Center, and Tel-Aviv University Sackler School of Medicine, Israel SUMMARY An axial computed tomographic (CT) scan of the lumbosacral regions was performed in 65 patients. The patient population was divided into two groups. The first (control) group included 40 elderly patients without calcification of the ligamenta flava. The second group included 25 patients with ankylosing spondylitis. More than 90% of those in the second group showed calcified lumbosacral ligamenta flava. In two patients these calcifications produced spinal stenosis. The diagnostic and practical importance of these findings are discussed. copyright. Calcification of the ligamentum flavum was first lumbosacral region (L3-S1). The patients were recognised in 1929.1 Only recently, however, was it divided into two groups. Group 1 included 40 found that such calcifications induced myelopathy.2 3 patients, 20 female and 20 male, aged between 41 Since then similar reports have been presented, most and 65 years, who underwent CT examination of the of which referred to the location of this condition in lumbosacral spine after complaints of low back pain. the thoracic spine, producing myelopathy.f7 Some Group 2 included 25 male patients, aged 20-54 of the reported cases, included mainly in the years, with ankylosing spondylitis, without CT morphological studies, were associated with calcifi- findings of prolapsed disc. An Elscint EXEL 2400http://ard.bmj.com/ cation and ossification of other spinal ligaments and CT scanner was used. All patients had a preliminary enlargement of the vertebral pedicles.8 In his study 250 mm long surview scan of the lumbosacral area on spinal column specimens, Hiraoka reported with a viewing angle of 900. In each intervertebral ossification of the ligamentum flavum in 44 out of space the tilt of the gantry was planned parallel to 128 (34%) spinal columns of cadavers of aged the disc space. The width of the slices was 5 mm, persons.9 Calcification and ossification of the liga- with 4 mm increment. A circle diameter of 140 mm menta flava in the cervical spine, associated or not was used with matrix 340/340 pixels. on September 26, 2021 by guest. Protected with myelopathy and radiculopathy, have also been reported. In several of the patients operations Results resulted in significant improvement. Cervical liga- menta flava calcifications have been found not All patients in group 1 had normal CT scans, and no rarely in elderly women as an incidental finding. 111-17 calcifications of the ligamenta flava were found. The Calcifications of the ligamenta flava in the lumbo- mild spondylarthritic changes found in some of the sacral spine have been reported as part of the patients were consistent with their age. Patients with spectrum of ligamentous calcifications of the entire senile vertebral ankylosing hyperostosis were not spine. The condition seems poorly understood and included in this group. has not been reported separately. All the patients in group 2 had findings of sacroiliitis and 'squaring' of the lumbar vertebrae on Patients and methods conventional radiographs. The older patients had syndesmophytes and ossifications of the spinal Sixty five patients underwent axial CT scan of the ligaments, producing 'bamboo spine'. All the patients in this group had juxta-articular osteoporosis around Accepted for publication 19 June 1987. calcifi- Correspondence to Dr Elieser Avrahami, Department of Radiology, the sacroiliac joints. In 23 patients (92%) Sourasky Medical Center, Ichilov Hospital, 64 239 Tel-Aviv, Israel. cations of the ligamenta flava were demonstrated at 62 Ann Rheum Dis: first published as 10.1136/ard.47.1.62 on 1 January 1988. Downloaded from Calcification of the ligamenta flava in ankylosing spondylitis 63 various levels, from L3 to Si. In the younger patients (below the age of 25 years), suffering from the disease for a considerably shorter duration of time, these calcifications were fine and not associ- ated with calcifications of other spinal ligaments. In older patients, with a longer duration of the disease, the calcifications of the ligamenta flava were coarse and not necessarily associated with calcifications and ossifications of other spinal ligaments. In two patients coarse calcifications of ligamenta flava resulted in clinical symptoms of spinal stenosis (Fig. 1). Ligamenta flava calcifications or ossifi- cations at more than one level (Fig. 2) were found in 12 patients. Eleven patients in this group also underwent axial CT scan of the cervical spine, which showed ligamenta flava calcifications in five of them (Fig. 1). These five patients had calcified or ossified spinal ligaments in the cervical spine, demonstrated on conventional radiographs. copyright. Fig. 2 A 42 year old man with ankylosing spondylitis. Right anterior syndesmophyte and calcified ligamentaflava E_I_ at the level ofL3-4 (upper image). Calcified ligamentaflava http://ard.bmj.com/ at the level ofSI andjuxta-articular sacral osteoporosis near the sacroiliac joints (lower image). __ ~~~~~~~~~~~Discussion Calcification of the flava in the lumbosac- ligamenta on September 26, 2021 by guest. Protected ral region is not sex dependent. Age probably plays __- a part when calcifications are already present. These calcifications may become coarser and more ossified with age. The lack of ligamenta flava calcifications in otherwise normal CT examinations is obvious in group 1, in which patients older than 40 years were selected. Also obvious is the high percentage of calcifications in group 2. They are seen at an early stage of the disease and are not associated with calcifications in other spinal ligaments. At this stage Fig.1 1A 53 yoldltheywith can be of diagnostic significance when other Fig. year patient 'ankylosmng spondylitis syptm ar nufcetfrth igoi.I le and neurogenic intermittent claudication. Calcifications of symptoms are lnsufficient for the diagnosis. In older the ligamentaflava (upper image). Coarse ossification ofthe patients, with a longer duration of the disease, these ligamentaflava at the level of L3, causing narrowing, calcifications become coarser, more ossified, and predominantly ofthe transverse diameter ofthe spinal canal can- result in spinal stenosis. Usually, in such (lower image). patients with ankylosing spondylitis, calcifications Ann Rheum Dis: first published as 10.1136/ard.47.1.62 on 1 January 1988. Downloaded from 64 Avrahami, Wigler, Stern, Caspi, Yaron and ossifications of other spinal ligaments are also ossified ligamenta flava in the lower thoracic region. No Shinkel spine. The calcifications Geka 1979; 7: 863-7. seen in the remainder of the 6 Omojola M F, Cardoso E R. Fox A J, Drake C G, Durward demonstrated in the cervical ligamenta flava in this J1. Thoracic myelopathy secondary to ossified ligamentum group are probably an expression of the general flavum. J Neurosurg 1982; 56: 448-50. process of spinal ligament calcifications and can be 7 Miyasaka K, Kaneda K, Ito T, Takei H, Sugimoto S. Tsuru M. spondylitis. Ossification of spinal ligaments causing thoracic radiculomyelo- useful in the early diagnosis of ankylosing pathy. Radiology 1982; 143: 463-8. Spinal soft tissue calcifications and spinal stenosis 8 Nagashima C. Myelopathy due to ossification of the posterior in ankylosing spondylitis are reported, but there has longitudinal and the yellow ligament. Saigai Igaku 1975; 18: been no separate study of the ligamenta flava.18-21 671-83. remains unclear. In 9 Hiraoka S. The ossification of the ligamentum flavum of the The aetiology of calcification spinal foramina. Geka nio Ryoiki 1955; 3: 6s1l1. inflamed joints, calcium pyrophosphate dihydrate 10 Nanko S, Takagi A, Mannen, T, et al. A casc of ccrvical has been found, and the phenomenon has been radiculo-myelopathy due to calcification of ligamcntum flavum. called 'pseudogout syndrome'. 22 Chondrocalcinosis Neurol Med Chir (Tokyo) 1976; 4: 205-10. such as 11 Kamakura K, Furukawa T, Takassu T, Mannen T, Toyokura also seems to arise in various conditions, Y. Cervical myelopathy due to ossification ot ligamenta flava. hereditary haemochromatosis, hy erparathyroidism, Rinsho Shinkeigaku 1978; 18: 96-102. diabetes mellitus, and gout.13 Ligamenta flava 12 Jyotoku Z, Harada H. A case of cervical myelopathy due to calcification, which is a non-specific phenomenon, calcification of the ligamentum flavum. Rinsho Seikei Geka conditions, as in the 1980; 15: 708-12. could well result from other 13 Kawano K, Yoshida S. Ohwada T, et al. Cervical radiculo- cases discussed in this study. myelopathy caused by deposition of calcium pyrophosphate Today there is no doubt that CT scanning is the dihydrate crystals in the ligamenta flava. J Neurosurg 1980; 52: best procedure for the demonstration of ligamenta 279-83. This could be of 14 Kida M, Tabata S. Calcified mass in the cervical ligamenta flava flava calcifications. demonstration as a cause of cervical myelopathy. Rinsho Seikei Geka 1981; 16: greater importance in the diagnosis of spinal con- 310-3. ditions. It provides important information to the 15 Kure M. Clinical significance of the calcification of ccrvicalcopyright. physicians performing surgery for decompression of ligamenta flava. J Japan Orthop Assoc 1980; 54: 1224-S5. warn the 16 Masaomi K, Itsushi B, Tadayoshi S. Myelopathy duc to the spinal canal. This information can also ossification of the ligamentum flavum of the cervical spine. A anaesthesiologist before the insertion of the needle report of two cases. Spine 1981; 6: 553-9. for epidural anaesthesia. 17 Nakajima K, Miyaoka M, Sumie H, Nakazato T. Ishii S. We are convinced that, if demonstrated, ligamenta Cervical radiculomyelopathy due to calcification of the ligamenta flava. Surg Neurol 1984; 21: 479-88. flava calcifications should be noted in the radiologist's 18 Bowie E A, Glasgow G L.