Abstract
The pathology of the lumbar spine, especially its instability, was studied in 104 patients with classical and definite RA. When horizontal and angular displacement was assessed by the method of Dupuis, the former was noted in 24% of the patients at flexion and in 14% at extension, while the latter was noted in 26%. RA-induced instability was considered to be ascribable mainly to erosion in the facet (apophyseal) joint (Type 1) and to erosion, collapse and destruction of the disc and vertebral body (Type 2) . Lumbago was experienced sometimes in 59% of the patients, but always experienced in only 11.5%. There was no significant difference in the stage and duration of RA, Lansbury's articular quotient, BMA and MCI between instability and non-instability groups.
