Clinical implications of rotator cuff degeneration in the rheumatic shoulder

In rheumatoid arthritis (RA) of the shoulder, loss of cartilage and soft tissue degeneration coexists with pain and reduced range of motion. We evaluated the presence of bony and rotator cuff degeneration in RA of the shoulder joint and assessed their relationship with pain and loss of functioning. We hypothesized that rotator cuff degeneration plays an important role in the presence of pain and loss of functioning of the rheumatic shoulder.

We used a cross-sectional study to assess both bony and rotator cuff involvement using plain anteroposterior radiographs, ultrasound, and computed tomography images. Additionally, we used an electromagnetic tracking device and a force transducer to evaluate range of motion and maximum force of the shoulder muscles. Between January 2003 and July 2004 we included 26 consecutive patients (51 shoulders). Twenty-one shoulders showed no or slight joint destruction, 15 showed intermediate destruction, and 15 showed severe destruction.

Only 19 shoulders showed an intact rotator cuff. Proximal migration of the humeral head and fatty degeneration of the infraspinatus muscle especially showed a significantly strong correlation with increased pain and function loss (R2 = 0.36, P < 0.001). In a multivariate regression analysis, proximal migration and fatty degeneration of the infraspinatus muscle were related most significantly with pain and reduced functioning in the shoulder joint.

Rotator cuff degeneration plays an important role in the daily functioning of the rheumatic shoulder. Prevention of rotator cuff degeneration may therefore play an important part in the treatment of the rheumatic shoulder.