Intramuscular fatty infiltration and physical function in controlled acromegaly.

Introduction: Patients with acromegaly show musculoskeletal symptoms which may persist despite disease control. Increased i.m. fat fraction is a known cause of muscle dysfunction in several disorders.
Objective: To assess the degree of fat fraction in thigh muscles of controlled acromegaly patients and its relationship with muscle dysfunction.
Methods: In a cross-sectional study, we included 36 patients with controlled acromegaly and 36 matched controls. We assessed the percentage of fat fraction in each thigh muscle, using MRI 2-point Dixon sequence, and muscle performance and strength using the gait speed, timed up and go, 30-s chair stand, and hand grip strength tests. We evaluated joint symptoms using the Western Ontario McMaster Universities Osteoarthritis Index (WOMAC).
Results: Intramuscular fat fraction was greater in patients than controls (P < 0.05 for muscle compartments, rectus femoris (RF), vastus intermedius (VI), adductor magnus (AM) and semimembranosus). Patients had slower gait speed and poorer performance on the 30-s chair stand and timed up and go tests than controls (P < 0.05). The greater fat fraction in the combined anterior-posterior compartment and in each muscle was associated with worse performance on timed up and go (P < 0.05). The fat fraction in the anterior-posterior compartment predicted performance on timed up and go after adjusting for muscle area, IGF-I and WOMAC functional and pain scores (β = 0.737 P < 0.001).
Conclusions: Patients with controlled acromegaly have greater thigh i.m. fatty infiltration, which is associated with muscle dysfunction. Futures studies are needed to elucidate the mechanisms underlying this relationship.