Intra-rater reliability of rehabilitative ultrasound imaging of the erector spinae and gluteus medius muscles.

Rehabilitative ultrasound imaging (RUSI) is an evolving tool which allows non-invasive quantification of muscle function. Currently, RUSI is used primarily in abdominal and lumbar multifidus muscles, and there is a need to expand its use to other clinically relevant muscle groups. The purpose of this study was to examine intra-rater reliability of RUSI measurements of erector spinae (ES) and gluteus medius (GM) muscle thickness at rest and at submaximal contraction in healthy participants.

Methods: ES and GM muscles of 30 participants were imaged at rest and submaximal contraction. Intra-rater reliability estimates using a single and average of three measurements were also compared.

Results: ICCs for both ES and GM muscle thickness ranged between .89 to .93 for single measures and from .94 - .97 for average measures.

Conclusion: This study confirms a high intra-rater reliability of ultrasound measurements of ES and GM muscle thickness when an average of three measures are used.