PAGETIC VERTEBRAL ANKYLOSIS AND DIFFUSE IDIOPATHIC SKELETAL HYPEROSTOSIS

Study Design. A retrospective radiologic analysis of Paget's disease o f the spine. Objectives. The prevalence, anatomic distribution, mechan isms of formation of Pagetic vertebral ankylosis (PVA) and the possibi lity of a relationship to diffuse idiopathic skeletal hyperostosis (DI SH) were assessed in a large population of persons with Paget's diseas e. Summary of Background Data, Acquired vertebral ankylosis is not a c ommon feature of the Paget's disease of the spine and its mechanisms o f formation remain unknown. In some reports, PVA was associated with r adiographic signs of DISH. Methods. Of 337 Pagetic patients monitored in the Division of Rheumatology from 1961 to 1990, all 245 who had ent ire spine radiographs were selected for study. Radiographs were studie d for signs of Pagetic vertebral lesions and for spinal lesions of DIS H. Results. The study group contained 156 men with a mean age of 68 ye ars (range 37-92) and 89 women with a mean age of 71 years (range 50-8 9). Fourteen PVA were observed on the radiographs of 11 men (mean age 68 years; range 60-76). One PVA was cervical, eight were thoracic, one thoracolumbar, three lumbar, and one lumbosacral. Eighty of the two h undred forty-five patients (32.6%) had characteristic features of DISH . Eight out of the eleven patients with PVA also had evidence of spina l lesions of DISH and radiographic features of DISH were observed cont iguous to ten of the fourteen PVA. Conclusions. The scarcity of PVA re ported in the literature and in our study (4.4% of 245 patients) sugge sts that constant progression of the disease from one vertebra to anot her by invasion of intervertebral disc space is rare. However, the hig her incidence of PVA in men, their preferential location at the thorac ic spine and their association with lesions of DISH suggest that progr ession of Pagetic lesions by invasion of bridging osteophytes may be a n important mechanism for the intervertebral spread of Paget's disease .