A comparison of results of 3-dimensional gait analysis and observational gait analysis in patients with knee osteoarthritis

Objective: This study aimed to investigate levels of validity, and inter- and intra-observer reliability of observational gait analysis (OGA) in clinical usage, done by the physical therapists with varying clinical experience, in subjects with knee osteoarthritis. Methods: The study included 33 subjects (22 female, 11 male; mean age: 58.24 ±9.14 years range: 46 to 81) clinically and radiographically diagnosed with bilateral knee osteoarthritis, and 4 physical therapists to observe the subjects’ gaits. The physical therapists were separated into two groups according to their professional experience: those with 10 or more years, and those with fewer than 10 years. Video recordings were made of the subjects undergoing three-dimensional gait analysis (3DGA). These recordings were then observationally assessed twice by the participating physical therapists with at least a 6-week interval between observations. OGA was done via a form comprising 11 kinematic and 5 temporo-spatial parameters. Results: Lowest levels of agreement in both validity (r=0.06, p 0.05), and inter- (ICC:–0.12-0.06) and intra-observer (ICC:0.30–0.45) reliability were found in the parameters of ankle dorsiflexion in initial contact phase and pelvic rotation in midstance phase. Highest inter- and intra-observer agreement was found in the temporo-spatial parameters of step width, double step length, cadence and velocity (ICC:0.61–0.80). Highest validity was found in pelvic tilt in stance phase (r=0.74–0.78, p 0.001). With the exception of stance phase, moderate or good agreement (r=0.52–0.69, p 0.05) was found in the temporo-spatial parameters. Conclusion: This study found that OGA assessment of temporo-spatial parameters had moderate or good validity and reliability. Assessment of the majority of kinematic parameters had fair or moderate validity and inter-observer reliabilty, and moderate or good intra-observer reliability.