Fatty Infiltration of Rotator Muscles: A Comparison of Cuff Tear Arthropathy and Glenohumeral Osteoarthritis

Abstract

Aim: Rotator cuff tear arthropathy (CTA) and glenohumeral osteoarthritis (OA) are age-related chronic diseases of the shoulder representing debilitating, painful conditions with functional loss.  Surgical intervention provides the most reliable treatment, but studies have shown that prognosis is contingent upon a variety of factors, one of the most reliable of which is fatty infiltration of the rotator cuff muscles.  This study tests the hypothesis that fatty infiltration (FI) is increased in CTA subjects compared with OA subjects.

Materials and methods: CTA subjects (n=22, age 71.9 ± 7.8 years) and OA (n=22, age 62.9 ± 9.6 years) subjects were evaluated for extent of fatty infiltration by Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) imaging using Goutallier’s classification system and a novel scoring system of % FI.

Results: Goutallier classification showed that FI of the supraspinatus and infraspinatus rotator cuff muscles in CTA subjects was greater than those in OA subjects (p= 0.0001, p = 0.003, respectively).  The % FI method revealed similar results (p= 0.003, p = 0.0008, respectively).  Neither classification system revealed significant differences in FI for the subscapularis or teres minor cuff muscles (Goutallier: p= 0.123, p=0.890; % FI: p= 0.142, p = 0.666, respectively).  Analysis using age-matched controls revealed similar results.  There was a strong correlation in scores for the two classification systems (Spearman r = 0.96, p < 0.0001).

Conclusion: Extent of fatty infiltration of the rotator cuff muscles in subjects suffering from rotator cuff tear arthropathy is significantly greater than in subjects with osteoarthritis.