A Novel MRI Classification System for Hip Abductor Muscle Atrophy: The Wisconsin Hip Abductor (WHAb) Classification...

Area of Science:

• Orthopedic surgery
• Radiology
• Musculoskeletal imaging

Background:

• Fatty atrophy of hip abductors negatively impacts surgical outcomes.
• A standardized classification system for this condition is lacking.

Purpose of the Study:

• To develop a reliable MRI classification system for hip abductor fatty infiltration.
• To assess the correlation between fatty infiltration grades and hip pathology.

Main Methods:

• Retrospective analysis of 200 hip MRIs from 100 patients.
• Development of a novel grading system for gluteus medius (GMed) and gluteus minimus (GMin) fatty infiltration.
• Correlation analysis between MRI grades and identified hip pathologies.

Main Results:

• The developed MRI classification system demonstrated moderate to substantial intra- and interrater reliability.
• Higher fatty infiltration grades in GMin and GMed correlated significantly with tendon tears, tendinosis, and intra-articular cartilage loss.
• Specific correlations were found between fatty infiltration and labral tears (GMin) and greater trochanteric bursitis (GMed).

Conclusions:

• A new, simple MRI classification system for hip abductor fatty atrophy has been established.
• This system effectively correlates fatty infiltration grades with various hip pathologies.
• The classification aids in evaluating hip abductor muscle degeneration and associated conditions.