Ultrasound imaging: Reliability of measurements of abdominal and multifidus muscle thickness and multifidus cross-sectional area of adults aged 50-79 years

Question: What is the procedural reliability of the measurement of abdominal and multifidus muscle thickness and cross-sectional area from ultrasound imaging of older adults?

Design: Intra-examiner procedural reliability study with repeated measurements one week apart.

Participants: Twenty-three older adults (70% male, age range 51-75 years) participating in a randomised controlled trial of vitamin D supplements for knee osteoarthritis.

Outcome measures: Ultrasound images of abdominal and multifidus muscle thickness and multifidus cross-sectional area.

Results: Reliability of abdominal muscle thickness measurements both at rest and contracted, and of multifidus cross-sectional area, were substantial (ICC 0.81-1.0). Reliability of multifidus measurements of muscle thickness at rest and contracted ranged from fair to substantial (ICC 0.55-0.86).

Conclusion: Abdominal muscle thickness and multifidus cross-sectional area of older adults can be measured using ultrasound imaging with similar reliability to that for younger adults. Reliability of multifidus muscle thickness at L4-5 level was lower than that reported previously for older adults.