Pagetic vertebral ankylosis and diffuse idiopathic skeletal hyperostosis

A retrospective radiologic analysis of Paget's disease of the spine.

The prevalence, anatomic distribution, mechanisms of formation of Pagetic vertebral ankylosis (PVA) and the possibility of a relationship to diffuse idiopathic skeletal hyperostosis (DISH) were assessed in a large population of persons with Paget's disease.

Acquired vertebral ankylosis is not a common feature of the Paget's disease of the spine and its mechanisms of formation remain unknown. In some reports, PVA was associated with radiographic signs of DISH.

Of 337 Pagetic patients monitored in the Division of Rheumatology from 1961 to 1990, all 245 who had entire spine radiographs were selected for study. Radiographs were studied for signs of Pagetic vertebral lesions and for spinal lesions of DISH.

The study group contained 156 men with a mean age of 68 years (range 37-92) and 89 women with a mean age of 71 years (range 50-89). 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 hundred forty-five patients (32.6%) had characteristic features of DISH. Eight out of the eleven patients with PVA also had evidence of spinal lesions of DISH and radiographic features of DISH were observed contiguous to ten of the fourteen PVA.

The scarcity of PVA reported in the literature and in our study (4.4% of 245 patients) suggests that constant progression of the disease from one vertebra to another by invasion of intervertebral disc space is rare. However, the higher incidence of PVA in men, their preferential location at the thoracic spine and their association with lesions of DISH suggest that progression of Pagetic lesions by invasion of bridging osteophytes may be an important mechanism for the intervertebral spread of Paget's disease.