Summary

We suggest that the peak timing of knee flexion moment could be helpful to understand the abnormal gait pattern and to develop the targeted rehabilitation for patients after total knee arthroplasty.

Abstract

Background

The patterns of knee joint loading during walking are diverse in patients with knee osteoarthritis (OA) before and after total knee arthroplasty (TKA). However, the gait mechanics by the different loading patterns are not fully understood. We aimed to compare the gait mechanics between groups distinguished by peak timing of knee flexion moment (KFM) and to identify whether altered knee joint loading pattern after TKA could be associated with pre-surgery gait function and how changed in adjacent joints.

Materials And Methods

Lower limb biomechanics and The Knee Injury and Osteoarthritis Outcome Score (KOOS) were assessed in 43 patients (60 legs) and 9 participants of the control group before and one year after TKA. An “earlier peak (EP)” (23 patients, 30 TKA legs) was defined as the peak of the external KFM during early stance phase and a “later peak (LP)” (20 patients, 30 TKA legs) was defined as the peak of the external KFM during late stance phase. Gait biomechanical data were collected using a three-dimensional motion analysis system. (Fig. 1)

Results

Most of parameters showed the improved changes in both of two groups after TKA (p<0.05). Significant effects of interactions between group and time were found for timing of peak KFM (p=0.001), foot progression angles (p=0.011), and K5 power absorption (p=0.030). The timing of peak KFM in EP group after TKA was faster (mean difference, 19.37sec) compared to LP and control group. The foot progression angle in LP after TKA increased compared to pre-operation (mean difference, 2.72°) and EP group (mean difference, 5.14°). K5 power absorption during terminal swing after TKA in LP group is significantly lower than both of EP and control group (p<0.05). Scores of pain and activities on daily living in LP group significantly lower than them in EP group before and after TKA.
In three group’s comparison, there were significantly decreases on H3 power generation, K2 and K5 power absorption, and walking speed in LP group, compared to both of EP and control group. Peak KFM increased significantly, but hip and knee extension moment, and ankle dorsiflexion moment and H1 power generation and K1 power generation decreased significantly in EP and LP group, compared to the control group. Peak hip adduction, knee flexion and ankle dorsiflexion angles, hip flexion moment, A2 power generation were significantly decreased in LP group compared to the control group.

Conclusion

The persistent gait abnormalities including toe out gait and reduction of knee absorption power during terminal swing were more noticeable in LP group. Patients who had more pain and less daily activity were included in LP group. We suggest that the peak timing of KFM could be helpful to understand the abnormal gait pattern and to develop the targeted rehabilitation for patients after TKA. Hip and knee muscle strengthening for EP group, and balanced exercise between medial and lateral muscles as well as hip, knee and ankle muscle strengthening for LP group should be applied after TKA.