Frontal knee alignment: three-dimensional marker positions and clinical assessment.

We assessed the validity of the hip-knee-ankle angle measured statically during three-dimensional (3-D) gait analysis and the tibial angle using an inclinometer compared with the mechanical axis on radiographs. Eleven individuals (20 knees) with radiographic knee osteoarthritis (OA) participated in this study. We determined the following: the lower-limb mechanical axis using weightbearing long-leg radiographs; hip-knee-ankle angle using the techniques of 3-D gait analysis in a static standing position; and tibial alignment using an inclinometer. The mean mechanical axis (+/- standard deviation) for this cohort was 0.7 degrees +/- 7.2 degrees (range, -13 degrees-16 degrees). The tibial alignment and hip-knee-ankle angle correlated with the mechanical axis but the correlation between the mechanical axis and the hip-knee-ankle angle was stronger. Our data suggest the inclinometer and 3-D gait analysis are valid ways to estimate mechanical alignment of the knee.