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Updated: Aug 31, 2026
Clinical-oriented Three-dimensional Gait Analysis Method for Evaluating Gait Disorder
Published on: March 4, 2018
The psychometric properties of Functional Gait Assessment (FGA) in assessing walking ability in people with knee
Shamay S M Ng1,2, Peiming Chen1, Timothy T Y Yung1
1Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Hong Kong Special Administrative Region of China.
Objective:
(1) Compare Functional Gait Assessment (FGA) scores between knee osteoarthritis (KOA) patients and healthy older adults; (2) assess FGA inter-rater/test-retest reliability in people with KOA; (3) examine the correlations between FGA scores and knee function measures; (4) identify the optimal FGA cutoff score for distinguishing people with KOA from healthy controls.
Methods:
This cross-sectional study included 63 individuals with KOA (mean age = 66.6 years) and 30 healthy older adults (mean age = 68.1 years). The participants were assessed by FGA, knee flexion/extension strength, Limit of Stability (LOS), Berg Balance Scale (BBS), Timed Up and Go (TUG), Five Times Sit to Stand (5STS), Activity-specific balance confidence (ABC) scale, Knee Injury and Osteoarthritis Outcome Score (KOOS), Falls Efficacy Scale-International (FES-I), and Oxford Participation and Activities Questionnaire (Ox-PAQ). The KOA group was assessed on Day 1 and Day 2 (7 days apart), whereas the healthy group was assessed on Day 1 only. Inter-rater and test-retest reliability of the FGA in the KOA group were evaluated using the Intraclass Correlation Coefficient (ICC). Correlations between FGA performance and other outcome measures were analyzed using Pearson's r or Spearman's rho. The optimal FGA cutoff score for differentiating between the KOA and healthy groups was determined using the Receiver Operating Characteristic curve.
Results:
People with KOA (mean ± standard deviation (SD) = 23.49 ± 3.87) had significantly lower(p < 0.001) FGA scores than healthy older adults (mean ± SD = 27.03 ± 2.51). The FGA demonstrated excellent inter-rater reliability (ICC = 0.986) and good test-retest reliability (ICC = 0.897). FGA scores showed moderate-to-strong positive correlations with affected knee strength, LOS, BBS, KOOS, and ABC (r = 0.36-0.70), and significant negative correlations with TUG, 5STS, FES-I, and Ox-PAQ scores (r = -0.32 to -0.69). The optimal FGA cutoff score was 25.5 (Area Under the Curve = 0.795-0.798, sensitivity = 0.867, specificity = 0.651-0.667) as a threshold to distinguish performance of people with KOA from healthy controls.
Conclusion:
The FGA showed promising overall reliability and selected validity evidence in this sample, while further confirmation in larger, more diverse cohorts is required.
