Assessing the validity and reliability of the foot tapping test in children with spastic cerebral palsy

Ankle control is essential for safe and effective ambulation in children with spastic cerebral palsy (CP). However, performance-based assessments targeting this function are limited. The Foot Tapping Test (FTT) may serve as a simple clinical measure of ankle control. Objective: This study aimed to investigate the validity and reliability of the FTT with spastic CP.

This cross-sectional study evaluates the FTT's validity, inter-rater reliability, and test - retest reliability. Convergent validity was analyzed using ankle dorsiflexion active range of motion (AROM), dorsiflexion strength, and the Five Times Sit-to-Stand Test (FTSST). AROM was measured through analysis of the angles of anatomical landmarks via ImageJ-Fiji. Retests were performed 7-10 days later.

Thirty-two children (mean age:10.66 ± 3.86 years; male n = 21) participated. The right (FTT_right) and left FTT (FTT_left) were moderately correlated with dorsiflexion AROM (r = 0.426 and r = 0.552, respectively; p < .05). They were weakly correlated with dorsiflexion strength (FTT_right r = 0.352 and FTT_left r = 0.368; p < .05), and FTSST (FTT_right: r = -0.362; FTT_left and r = -0.386; p < .05). Inter-rater reliability was excellent for FTT_right (ICC_(2,1) = 0.982) and FTT_left (ICC_(2,1) = 0.991). Test - retest reliability was good for raters A (FTT_right, ICC_(2,1) = 0.835; FTT_left, ICC_(2,1) = 0.887) and B (FTT_right, ICC_(2,1) = 0.830; FTT_left, ICC_(2,1) = 0.892). Bland - Altman analysis showed good inter-rater and test-retest agreement, with mean differences near zero. Limits of agreement were narrow between raters (-1.8 to 2.0) and wider across repeated testing (-6.3 to 5.8).

The FTT was a valid and reliable tool for assessing ankle control in children with spastic CP, including those with diplegic and hemiplegic presentations. Also, FTT is a clinically valuable assessment for routine use, given its simplicity and feasibility with the important role that ankle control plays in gait and balance.