Gait retraining to reduce the knee adduction moment through real-time visual feedback of dynamic knee alignment

Abstract

Varus knee alignment is a risk factor for medial knee osteoarthritis and is associated with high knee adduction moments. Therefore, reducing the knee adduction moment in varus-aligned individuals with otherwise healthy knees may reduce their risk for developing osteoarthritis. A gait modification that improves dynamic knee alignment may reduce the adduction moment, and systematic training may lead to more natural-feeling and less effortful execution of this pattern. To test these hypotheses, eight healthy, varus-aligned individuals underwent a gait modification protocol. Real-time feedback of dynamic knee alignment was provided over eight training sessions, using a fading paradigm. Natural and modified gait were assessed post-training and after 1 month, and compared to pre-training natural gait. The knee adduction moment, as well as hip adduction, hip internal rotation and knee adduction angles were evaluated. At each training session, subjects rated how effortful and natural-feeling the modified pattern was to execute. Post-training, the modified pattern demonstrated an 8 degrees increase in hip internal rotation and 3 degrees increase in hip adduction. Knee adduction decreased 2 degrees , and the knee adduction moment decreased 19%. Natural gait did not differ between the three visits, nor did the modified gait pattern between the post-training and 1 month visits. The modified pattern felt more natural and required less effort after training. Based on these results, gait retraining to improve dynamic knee alignment resulted in significant reductions in the knee adduction moment, primarily through hip internal rotation. Further, systematic training led to more natural-feeling and less effortful execution of the gait pattern.

Figure 1

Clinical measurement of tibial mechanical axis with a caliper-inclinometer device using procedures modified from Hinman and colleagues (2006).

Figure 2

Actual screen image depicting the knee adduction angle data of a varus-aligned subject during training against a shaded region representing ± 1 standard deviation of a normative mean for knee adduction angle. Knee adduction is positive, and the previous two stance-phases are shown. Note the downward deflection in knee adduction angle in early stance, around the same time that peak KEAM occurs.

Figure 3

Chart depicting time spent walking on the treadmill during each session, and the respective time with visual feedback for each session. For the first four sessions, subjects received feedback 100% of the session. By visit 8, feedback was provided for 10% the session.

Figure 4

How effortful and natural-feeling the modified gait pattern was perceived across training sessions. Effort: 0 = effortless, 10 = maximal effort. Naturalness: 0 = natural, 10 = maximally unnatural. Error bars depict standard deviations.

Figure 5

Ensemble averaged curves comparing the modified gait post-training to the baseline visit, depicting decreases in KEAM and knee adduction, and increases in hip adduction and internal rotation. Error bars depict standard deviations.

Figure 6

Average percentage of walking between training sessions during which subjects reported using the modified pattern. Error bars depict standard deviations.