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.
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.
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.
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.