A Comparison of Dynamic and Static Hip-Knee-Ankle Angle during Gait in Knee Osteoarthritis Patients and Healthy Individuals

Abstract

Malalignment of the lower limbs is the main biomechanical factor for knee osteoarthritis (KOA). The static hip-knee-ankle angle (S-HKAA) measured from radiograph is regarded as the "gold standard" of the malalignment. However, many evidences showed that the S-HKAA has no significant correlation with the knee dynamic-load distribution, unlike the dynamic HKAA (D-HKAA). The purpose of this study was to quantitatively analyze the D-HKAA and investigate the relationship between D-HKAA and S-HKAA for both KOA and healthy participants. In this paper, twenty-five healthy subjects and twenty-five medial compartment KOA (M-KOA) patients were recruited. Three-dimensional motion analysis and standing lower-limbs-full-length radiograph were utilized to obtain the D-HKAA and S-HKAA, respectively. The results showed that the mean D-HKAA was more varus than the S-HKAA (p < 0.05). For the mean D-HKAA, larger varus angle was observed in swing phase than stance phase (p < 0.05). Compared with healthy subjects, the M-KOA patients had remarkably smaller S-HKAA and D-HKAA during gait cycle (p < 0.01). For the relationship between the S-HKAA and mean D-HKAA, no significant correlation was found for both healthy subjects and M-KOA patients (r < 0.357, n = 25, p > 0.05, Spearman correlation analysis). In conclusion, the S-HKAA was limited to predict the D-HKAA for both M-KOA patients and healthy subjects. The D-HKAA should be given more attention to the orthopedist and the designer of knee brace and orthotics.

Figure 1

Standing lower-limbs-full-length anterior-posterior radiographs of healthy subjects (a) and medial compartment knee osteoarthritis (M-KOA) patients (b). Static hip-knee-ankle angle (S-HKAA) was obtained by drawing lines connecting the hip, knee, and ankle joint centers. The hip, knee, and ankle joint centers were defined as the center of the femoral head, the midpoint of the femoral epicondyles, and the midpoint of the medial and lateral malleolus, respectively.

Figure 2

Gait experiment and dynamic data processing: (a) gait experiment, (b) musculoskeletal simulation model, and (c) dynamic hip-knee-ankle angle (D-HKAA).

Figure 3

Typical S-HKAA (dash line) and D-HKAA (mean: solid line and SD: shading) curves during gait cycle of healthy subject (red line) and M-KOA patient (blue line) (The vertical red and blue shading represent the boundaries between stance and swing phase, initial and middle stance subphase, and middle and terminal stance subphase for healthy subjects and M-KOA patients, respectively.)

Figure 4

S-HKAA and mean D-HKAA for healthy subjects and M-KOA patients, A S-HKAA and mean D-HKAA of whole gait cycle, B D-HKAA of stance phase and swing phase, and C D-HKAA of initial, middle, and terminal stance subphase.

Figure 5

Knee joint angle curves of healthy subjects (mean: red solid line and SD: red shading) and M-KOA patients (mean: blue dash line and SD: blue shading) during gait (The vertical red and blue shading represent the boundary between stance phase and swing phase for healthy subjects and M-KOA patients, respectively.)