The purpose of this study was to develop a Korean version of the pediatric functional muscle testing(K-PFMT) for the children with motor developmental disorder who have the problem of communication, aged below 5 years, and to verify the reliability and validity.
First, the preliminary study was conducted for verification of the reliability of pediatric functional muscle testing which was developed by Venita(2006) in Korea. Based on the results of the study, the primary evaluation items were selected and modified.
Second, the first content validity was conducted through panel discussion, an investigation of the second content validity was carried out by utilizing the Item Content Validity Index (I-CVI). Based on this, the 15 tertiary evaluation items for the K-PFMT were determined.
Third, internal consistency, inter-rater reliability, test-retest reliability, and concurrent validity were conducted for verification of reliability and validity of the K-PFMT. The subjects were 40 children, aged below 5 years, with 20 cerebral palsy and 20 developmental delay. Each was scored on the K-PFMT by 14 physical therapists to determine inter-rater reliability and internal consistency. The 3 of 14 therapists also tested 20 children again one or two weeks later to determine test-retest reliability. The internal consistency of the K-PFMT was calculated by Cronbach''s alpha. The inter-rater and test-retest reliability were calculated with the intraclass correlation coefficient (ICC). To compare differences among 3 evaluator groups, the one-way ANOVA was used. To compare differences between test and retest, paired t-test was used. Concurrent validity was evaluated by Pearson correlation with the total score of GMFM.
The results of this study as follows:

1. Chronbach''s alpha was over 0.98 in each testing items and 0.99 in total items. The high score of internal consistency indicated an excellent level of reliability.

2. The inter-rater ICC of the score of month and muscle strength of the K-PFMT in children with cerebral palsy was from 0.89 to 1.00 and from 0.65 to 1.00, respectively. The inter-rater ICC of the score of month and muscle strength of the K-PFMT in children with developmental delay was from 0.71 to 1.00 and from 0.46 to 0.98, respectively. There was no significant difference in the score of the K-PFMT among three evaluator groups except for a few items.

3. The test-retest ICC of the score of month and muscle strength of the K-PFMT in 20 children with cerebral palsy and developmental delay was from 0.89 to 1.00 and from 0.82 to 1.00, respectively. There was no significant difference in the score of the K-PFMT between test and retest except for a few items.

4. There were high significant correlations between the score of K-PFMT and the total score of GMFM in 40 children.

In conclusion, this study showed that the New Korean version of PFMT was developed, and the reliability and validity of the K-PFMT was relatively high. Therefore, it can be suggested that the K-PFMT will be a useful tool for measurement of muscle strength for children with motor developmental disorder who have the problem of communication, aged below 5 years, in Korea.