Immediate and short-term effects of gait retraining on the knee joint moments and symptoms in patients with early tibiofemoral joint osteoarthritis: a randomized controlled trial.

OBJECTIVE: To evaluate the effectiveness of a knee adduction moment (KAM) gait retraining in patients with early knee osteoarthritis up to 6 months post-training. METHOD: We conducted a single blinded randomized controlled trial on a total of 23 patients with early knee osteoarthritis who were randomly allocated to the gait retraining group and walking exercise group. Twenty of them completed the corresponding training and the 6-month evaluation. We measured KAM, knee flexion moment (KFM) and western ontario and McMaster universities osteoarthritis index (WOMAC) osteoarthritis index before, immediate after, and 6 months after training. A repeated measures analysis of covariance (ANCOVA) was used to compare KAM, KFM and WOMAC osteoarthritis index scores across the three time points i.e., pre-training, post-training, and 6-month follow-up with gender, knee osteoarthritis severity, and pre-training KAM, KFM and WOMAC scores set as covariates. Post-hoc analyses were conducted when indicated. RESULTS: Significant time × group interactions were found for both KAM and WOMAC osteoarthritis index scores (P < 0.002). No interaction was found for KFM (P = 0.123). KAM after gait retraining was significantly lower than the pre-training value (P < 0.001) and such effect was maintained at 6-month follow-up (P = 0.01). There was no significant difference in the KAM across time in the walking exercise group (P > 0.208). WOMAC osteoarthritis index score after training and score at the 6-month follow-up were significantly improved in the gait retraining group (P = 0.001), while the WOMAC osteoarthritis index score remained similar. CONCLUSIONS: Gait retraining is an effective intervention to reduce KAM during walking and to improve the symptoms of patients with early knee osteoarthritis in short term.

Immediate effects of modified landing pattern on a probabilistic tibial stress fracture model in runners.

BACKGROUND: Tibial stress fracture is a common injury in runners. This condition has been associated with increased impact loading. Since vertical loading rates are related to the landing pattern, many heelstrike runners attempt to modify their footfalls for a lower risk of tibial stress fracture. Such effect of modified landing pattern remains unknown. This study examined the immediate effects of landing pattern modification on the probability of tibial stress fracture. METHODS: Fourteen experienced heelstrike runners ran on an instrumented treadmill and they were given augmented feedback for landing pattern switch. We measured their running kinematics and kinetics during different landing patterns. Ankle joint contact force and peak tibial strains were estimated using computational models. We used an established mathematical model to determine the effect of landing pattern on stress fracture probability. FINDINGS: Heelstrike runners experienced greater impact loading immediately after landing pattern switch (P<0.004). There was an increase in the longitudinal ankle joint contact force when they landed with forefoot (P=0.003). However, there was no significant difference in both peak tibial strains and the risk of tibial stress fracture in runners with different landing patterns (P>0.986). INTERPRETATION: Immediate transitioning of the landing pattern in heelstrike runners may not offer timely protection against tibial stress fracture, despite a reduction of impact loading. Long-term effects of landing pattern switch remains unknown.