Frontal Knee Alignment: Three-dimensional Marker Positions and Clinical Assessment

Abstract

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°± 7.2°(range, -13°-16°). 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.

The Chitranjan Ranawat Award: Is Neutral Mechanical Alignment Normal for All Patients?: The Concept of Constitutional Varus

“…The rotational position of the knee compared to the hip and ankle is variable, and a perceived constitutional varus could therefore in fact be an external rotation of one subject's limb as compared to another. In our study, however, the rotational position of the lower extremities was controlled by positioning the extremities with the patellae facing forward, as was used by many previous authors who have studied lower leg alignment [7,18,21,22,26,28,38]. We believe, by doing so, the rotational effect is minimized.…”

“…The second limitation to our study is the use of full-leg standing radiographs for our measurements. Although this method is well validated in the literature and has excellent intra-and interobserver reliability, the rotational position of the lower extremities might influence the outcome of the measurements [8,12,13,21,27,38]. The rotational position of the knee compared to the hip and ankle is variable, and a perceived constitutional varus could therefore in fact be an external rotation of one subject's limb as compared to another.…”

“…The whole pelvis was included in the radiographs and the gonads were always shielded. All radiographs were calibrated and all measurements were performed by the same person (WC) using the AGFA PACS software package (Agfa-Gevaert) and previously described methodology [3,13,22,26,28,36,38].…”

Clinical methods for quantifying body segment posture: a literature review

“…The frontal knee alignment measured with an inclinometer has good correlation with measurement of mechanical axis of the leg on radiographs (r=0.83) [57].…”

“…The validity of measurements taken with goniometers and inclinometers has been concurrently assessed with radiographs only for shoulder protraction, lumbar lordosis, sagittal pelvic tilt and frontal lower limb alignment [51][52][53][54][55][56][57] (Table 1 For lower limb alignment assessment, correlation between goniometer measurements of Q angle and rearfoot alignment (tibiocalcaneus angle) and radiographs were weak to moderate (r=0.32 and 0.74 respectively) [53,56]. The frontal knee alignment measured with an inclinometer has good correlation with measurement of mechanical axis of the leg on radiographs (r=0.83) [57].…”