Subacromial space in the rheumatoid shoulder: A radiographic 15-year follow-up study of 148 shoulders

A cohort of 74 patients with rheumatoid arthritis was monitored prospective ly for 15 years. At the end of the study 148 shoulders were radiographed wi th a standard method. The subacromial space was examined from the radiograp hs with a method where the acromiohumeral interval was measured from the de nse cortical bone marking the inferior aspect of the acromion to a point di rectly above the head of the humerus. The smallest distance was recorded, a nd negative values were used when the original articular surface of the hum erus exceeded the inferior surface of the acromion. Destruction of the glen ohumeral (GH) joints was assessed by the Larsen method on a scale of 0 to 5 The relation of subacromial space measurement to the grade of destruction of GH joints was examined. The mean subacromial space was 6.7 (SD 4.4), ran ge from -13 to 12 mm: 6.1 mm (SD 5.6) in men and 6.9 mm (SD 4.0) in women. The mean of nonaffected (Larsen grade 0 or 1) shoulders (n = 77) was 8.6 mm (SD 1.5) and the corresponding mean of the affected (Larsen grade greater than or equal to 2) shoulders (n = 77) was 4.6 mm (SD 5.5). Previously repo rted pathologic criterion (<6 mm) indicating rotator cuff involvement was f ulfilled in 30 (20%) of 148 shoulders: in 8 (22%) of 36 shoulders in men an d in 22 (20%) of 112 shoulders in women. All the shoulders with severe rheu matoid destruction (Larsen grade 4 or 5) fulfilled the pathologic limit. Th e subacromial space herd a significant negative correlation with the GH joi nt destruction (Larsen grade) in both sides: right r = -.63 (95% CI -.75 to -.47), left r = -.71 (95% CI-.81 to -.58). Progressive upward migration is an inevitable consequence of rheumatoid destruction in the GH joint. A sig nificant step in this process occurred between the Larsen grades of 3 and 4 , where the mean distance turned negative, indicating rotator cuff disease. A patient with rheumatoid arthritis and painful shoulder and upward migrat ion of the humerus on the shoulder radiograph should be evaluated by an ort hopaedic surgeon. In indistinct cases with subacromial space diminution, im aging techniques like ultrasonography or magnetic resonance imaging may be required to determine the exact pathologic condition of the rotator cuff an d to select optimal treatment.