Radiographic joint space in rheumatoid elbow joints. A 15-year prospectivefollow-up study in 74 patients

Objective. To evaluate radiographically the humeroulnar (HU) and humeroradi al (HR) joint spaces in patients with long-term rheumatoid arthritis (RA). Methods. An inception cohort of 74 patients with RA were followed for 15 yr . At the end-point, 148 elbows were radiographed by a standard method. The HU and HR joint spaces were examined from the anteroposterior radiographs b y measuring the shortest tangential distance in the middle of the joints. D estruction of the elbow joints, assessed with the Larsen method on a scale of 0-5, was studied in relation to the joint-space measurements. Results. Mean (S.D.) HU joint space (n = 148) in RA patients was 2.5 (1.1) mm, range 0-4 mm [2.9 (0.8) mm in men and 2.4 (1.1) ram. in women]. Mean (S .D.) HR joint space (n = 140) was 23 (0.9) mm, range 0-4 mm [2.5 (0.8) turn in men and 2.3 (1.0) mm in women]. HU and HR spaces of the affected joints (Larsen grades 2-5) [1.9 (S.D. 1.1) and 1.8 (0.9) mm respectively] were no tably narrower than those of the unaffected (Larsen grades 0-1) joints [3.1 (0.7) and 2.9 (0.6) mm]. All the joints graded as Larsen 4 or 5 (n = 13) h ad a value of 0 mm for both joint spaces. Both the HU and the HR joint-spac e narrowing was associated with increasing destruction (Larsen grading) of the joint. [r = -0.69 (95% CI -0.77 to -0.60) and r = -0.70 (-0.78 to -0.60 )]. The monotonic narrowing was significantly increasing from unaffected (L arsen 0, 1), slightly (2), moderately (3) to severely (4, 5) affected joint s (P < 0.001). A step in this process occurred between Larsen grades 3 and 4, when the mean joint space diminished from 1.4 and 1.5 respectively to 0 mm. Conclusions. Joint-space narrowing is a frequent consequence of rheumatoid affection of the elbow joint. HR joint space decreases together with HU joi nt space; however, the HR joint space is already slightly narrower at the s tart. The narrowing is a rather late phenomenon, occurring only after erosi ve destruction. This should be borne in mind when using the Larsen method t o evaluate changes in the elbow joint.