Fatty infiltration and muscle atrophy: What it means and what happens after repair?

Abstract

Fatty infiltration (FI) and muscle atrophy are common findings following RC tears. Fatty degeneration varies among rotator cuff muscles. The pathophysiology is complex, and is characterized by increased fibrosis. Age is reported to correlate with degeneration and atrophy. MRI and CT scans are used for exact diagnosis and grading of fatty degeneration according to Goutallier. Rotator cuff atrophy is usually assessed using the occupational ratio (Thomazeau grading) and "tangent sign." Fatty degeneration is associated with tendon re-tear and postoperative muscle atrophy. Furthermore, fatty changes probably negatively affect the clinical outcome regardless of tendon re-rupture. FI and muscle atrophy are considered as negative prognostic factors for shoulder function and clinical outcomes after repair of RC tears. Tendon repair has a controversial effect on infiltration progression. Most studies demonstrate improvement or reversal of muscle atrophy after cuff repair. However, there are also studies indicating no effect of the repair in degeneration process.