Disco-vertebral destructive lesions (So-called Andersson Lesions) associated with ankylosing spondylitis

Radiological examination of 31 patients with established ankylosing spondylitis revealed 58 disco-vertebral destructive lesions. Careful assessment of their radiological features permitted differentiation into two main types, (1) inflammatory and (2) non-inflammatory. The inflammatory type may represent either an active inflammatory process or a late sequel to such a lesion. In this series 44 lesions were included in this category, with a marked predilection for the lumbar spine. Moreover, all were observed within the first decade following the onset of the disease.The non-inflammatory type reflects an attempt of a stress fracture in the diseased spinal column to repair by connective tissue, causing a pseudoarthrosis. Eleven such lesions were obseved in this series all occurring more than 12 years after the onset of the disease. In a much smaller group of three cases-here termed the ambivalent type — differentiation between the inflammatory and non-inflammatory types could not be established on radiological grounds alone. It is of interest that all three cases occurred within the first year after the onset of the disease.It is suggested that the term Andersson lesion should be used to include all disco-vertebral destructive lesions related to ankylosing spondylitis—be they of inflammatory or non-inflammatory pathogenesis —as the better known term Romanus lesion includes all types of circumscribed marginal destructive lesions of vertebral bodies without involvement of the disc in ankylosing spondylitis.