Fatty degeneration or infiltration of the rotator cuff musculature is a consequence of chronic rotator cuff muscle tears. The precise cause of this degeneration is unknown; however, it has been proposed that degeneration results from the lack of neurogenic feedback, imbalance in the muscle tendon stress/strain, or physiologic changes in the muscles themselves resulting from tendon bone discontinuity. Independent of cause, the rotator cuff muscles ultimately display degeneration and atrophy with fatty replacement in addition to scarring and retraction of the muscle-tendon unit.
Goutallier first described a method for classifying fatty infiltration of the rotator cuff in 1994. This scheme was originally used for assessing fatty infiltration of the infraspinatus and subscapularis muscles using axial computed tomography arthrography (CTA). Fuchs later applied this classification scheme to magnetic resonance imaging (MRI) as it became an integral and commonly used method for the evaluation of rotator cuff integrity. Since the publication of these landmark studies, there has been considerable debate regarding the clinical application of this grading scheme in relation to several shoulder surgical procedures, including rotator cuff repairs and both conventional and reverse shoulder arthroplasty. Several authors have shown that the degree of fatty infiltration negatively affects the clinical outcomes of patients when specifically regarding rotator cuff repairs. In addition, it has been shown that even after a successful rotator cuff repair (anatomic and clinical), fatty infiltration does not improve in patients.
Because of the clinical implications of fatty infiltration in rotator cuff tears, there have been several efforts to ensure that the Goutallier scheme is reliable and valid. Despite the widespread use of this system, several authors have questioned its validity, and others have proposed new classification schemes. Such questions have emerged because of a number of variables affecting standardization, including which imaging modality and plane to use as well as identifying which rotator cuff muscle most effectively classifies a tear. Furthermore, the lack of knowledge regarding whether atrophy or fatty infiltration of the rota- tor cuff musculature is responsible for poor outcomes after repair of tears has led to difficulty in defining a classification system that is clinically relevant.
The purpose of this study was to determine the inter-and intraobserver reliability of the Goutallier classification scheme for rotator cuff infiltration using a large cohort of subspecialty trained sports and shoulder surgeons.