Pagetic vertebral ankylosis and diffuse idiopathic skeletal hyperostosis.

STUDY DESIGN: A retrospective radiologic analysis of Paget's disease of the spine. OBJECTIVES: 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. SUMMARY OF BACKGROUND DATA: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

[Mechanisms of spinal block formation in Paget disease of bone. Radiographic study based on 14 cases]. / Mécanismes de formation des blocs vertébraux pagétiques. Etude radiographique à partir de 14 blocs.

Vertebral bridging occurs in approximately 10% of patients with spinal pagetic lesions. Diffuse idiopathic skeletal hyperostosis has been reported in patients with pagetic block vertebras and may facilitate vertebral fusion and extension of pagetic lesions. High prevalences of diffuse idiopathic skeletal hyperostosis have been found in patients with Paget's disease. To determine how pagetic block vertebras develop and to investigate relationships between Paget's disease and diffuse idiopathic skeletal hyperostosis, 244 patients with Paget's disease were studied retrospectively. Diagnostic criteria for diffuse idiopathic skeletal hyperostosis were the presence of flowing ossification along the anterolateral aspect of at least three contiguous vertebral bodies or presence of at least two anterolateral intervertebral bony bridges in the same spinal segment. Eight (33%) of the 244 patients had diffuse idiopathic skeletal hyperostosis. Two-thirds of patients with both conditions were male. There was no statistically significant association between presence of diffuse idiopathic skeletal hyperostosis and spinal involvement by Paget's disease. Fourteen pagetic block vertebras were identified in 11 male patients. Eight of these 11 patients had involvement of the fused vertebras or adjacent vertebras with diffuse idiopathic skeletal hyperostosis. Our findings confirm that diffuse idiopathic skeletal hyperostosis is common in patients with Paget's disease. The statistically significant association between diffuse idiopathic skeletal hyperostosis and pagetic vertebral fusion in the same site suggests that the former condition may be a risk factor for pagetic vertebral bridging.