Clinical evaluator reliability for quantitative and manual muscle testing measures of strength in children
Escolar DM, Henricson EK, Mayhew J, et al. Clinical evaluator reliability for quantitative and manual muscle testing measures of strength in children. Muscle & Nerve. 2001;24(6):787-793. doi:10.1002/mus.1070
Purpose: Testing muscle strength is an important part of a pediatric evaluation. Traditionally, specific muscle groups have been tested using manual muscle testing (MMT) which has been shown in other studies to be subjective and requiring significant experience to perform consistently. An alternative measure, quantitative muscle testing (QMT), uses a strain gauge to measure maximal voluntary isometric contraction and has been tested in studies with patients who have amyotrophic lateral sclerosis (ALS). The authors’ purpose in this study was to determine if QMT would be more reliable and easier to implement that MMT.
Methods and Intervention: The subjects of the study were ten physical therapists and two physicians who had 6.92 5.46 years of experience evaluating children, 6.75 4.13 years evaluating children with neuromuscular disease, and 2.00 2.33 years of experience in clinical research. The subjects were divided into groups of 4, and trained to use MMT and QMT to assess strength in 12 ambulatory children age 9.33 3.08 with varying types of muscular dystrophy. MMT was used on 5 muscles groups and QMT was used on 4 muscle groups, having leg extension, elbow flexion, and ankle dorsiflexion in common. MMT tested muscle groups included shoulder abduction and hip flexion strength while QMT included grip strength.
Results: Two of the three groups (8 subjects) had large differences in scoring when using MMT and had to undergo a second training session before performing a second MMT reliability test. All of the groups had more similar scores when using QMT, except for measuring foot dorsiflexion strength due to the presence of ankle contractures.
Author’s Conclusion: The authors found that QMT was easier for clinicians to use and gave more reliable results when children with muscular dystrophy were tested by multiple clinicians. MMT is reliable in this population but requires more experience and more clinicians to be an accurate assessment.
Assessment of Strengths and Weaknesses: QMT appears to be a promising test to measure pediatric strength when comparing consistency of strength measurements to MMT. There is still a requirement for experience and training when using QMT and MMT, while QMT also has the disadvantage of requiring a specific tool rather than a clinician’s hands. The sample size for the subjects performing the testing had a wide range of experience and was also small, with only 12 clinicians. Additionally, no mention was made to if there was a difference in the amount of time required to perform QMT testing. Overall, QMT seems to be a promising tool for measuring pediatric strength and would help provide a more objective measurement.