Validation of Manual Muscle Testing (MMT) in children and adolescents with cerebral palsy.

Background: Weakness is a major impairment in many movement disorders, including cerebral palsy (CP), which presents as a decrease in muscle strength. Manual muscle testing (MMT) is very popular in clinical practice, however it has many limitations.
Objective: (1) Whether maximum voluntary contraction (MVC) measures differ across clinical MMT groups; (2) Whether an association exists between clinical MMT score groups and instrumental MVC measures.
Methods: Twenty-one participants with spastic CP were recruited (11 females and 10 males; age = 13.46±3.62 years). To achieve the aims of the study, we investigated the relationship between qualitative (MMT) and instrumental (MVC) measures of knee flexor muscles' strength in patients with CP.
Results: MVC values increased somewhat proportionally with increasing MMT score group (p = 0.032, MS = 207.54, F = 3.75). The differences in MVC values was only statistically significant between score groups 3 and 5. A weak correlation (R = 0.4, MVC = -2.54 + 4.50 MMT, p < 0.01) was found between measured MVCs and the MMT score groups.
Conclusions: In pediatric research studies, instrumental MVC should be preferred over MMT scoring. Also, MMT score groups higher than 3 should be modified in clinical testing of children and adolescents with cerebral palsy.