Rheumatoid Arthritis of the Shoulder: Radiological Presentation and Results of Arthroplasty

Summary

Fifty rheumatoid shoulders (44 patients) treated with an Aequalis shoulder arthroplasty were reviewed with an mean follow-up of 20 months (12–45). Three radiographic forms were distinguished as defined on two criteria: the sphericity of the humeral head and upward migration of the head in relation to the glenoid. The three forms (similar to those described by Neer) do not have the same functional prognosis after insertion of a prosthesis. The “centered” (or dry) form (36%) occurs in patients with an average age of 58 years and is reminiscent of the radiographic appearance seen in osteoarthritis with a normal acromio-humeral distance (only 6% of cuff tear). The main problem is stiffness, with a limited gain in active anterior elevation regardless of the preoperative range of movement (average elevation 123°, gain 24°). The “destructive” (or wet) form (19%) characterised by destruction of the humeral head which loses its sphericity because of marginal erosion. It occurs in younger patients (average 47 years). The cuff is often damaged (33% of cuff tear), and there is wear which rapidly involves all the articular surfaces. Paradoxically, the best functional results were seen in this destructive form, with an average in active anterior elevation of almost 70° (average 154° of active elevation, gain 68°). The “ascending” (or resorptive) form (41%) characterised by upward migration of the humeral head which precedes superior glenoid wear in patients which are 61 years old. The frequent presence of a cuff tear (26%) penalises postoperative recovery of active anterior elevation (average elevation 116°, gain 28°) and external rotation. Finally, 8 press fit humeral components demonstrated progressive loosening with distal migration whereas no signs of loosening were found in the 42 cemented humeral components. A distal migration of the humeral component superior to 5 mm (6 cases) was clearly associated with decrease functional result. This emphasizes the necessity to cement the humeral component in the rheumatoid shoulder.