Reduction in knee adduction moment via non-invasive biomechanical training: A longitudinal gait analysis study Amir Haim a,b,n , Guy Rubin c , Nimrod Rozen c , Yulya Goryachev a , Alon Wolf a a Biorobotics and Biomechanics Lab (BRML), Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa, Israel b Department of Orthopedic Surgery, Sourasky Medical Center, Tel Aviv, Israel c Department of Orthopaedic Surgery, Ha’Emek Medical Center, Afula, Israel article info Article history: Accepted 5 October 2011 Keywords: AposTherapy Footwear-generated biomechanical training Gait analysis Knee adduction moment Knee osteoarthritis Plasticity of gait patterns abstract Biomechanical non-invasive interventions have been previously reported to reduce pain and facilitate superior levels of function in patients with medial knee osteoarthritis [OA]. One such treatment is the AposTherapy, a customized program utilizing a foot-worn biomechanical device allowing center of pressure modification and continuous perturbation during gait. The influence of this intervention on objective gait metrics has yet to be determined. The aim of the current study was to prospectively examine changes in kinetic and kinematic parameters in patients enrolled in this treatment program. Twenty-five females with symptomatic bilateral medial compartment knee OA were enrolled in the customized daily treatment program. All patients underwent barefoot gait analysis testing and completed subjective questionnaires prior to treatment initiation and on two follow-up visits. Significantly reduced knee adduction moment (KAM) magnitude was noted during barefoot walking after three and nine months of treatment. On average, the knee adduction impulse and the 1st and 2nd KAM peaks were reduced by 13%, 8.4%, and 12.7%, respectively. Furthermore, moment reduction was accompanied by elevated walking velocity, significant pain reduction, and increased functional activity. In addition to symptomatic improvement, our results suggest that this treatment program can alter kinetic gait parameters in this population. We speculate that these adaptations account for the symptomatic and functional improvement reported for this intervention. & 2011 Published by Elsevier Ltd. 1. Introduction Osteoarthritis (OA) is a complex disorder of the hyaline joints, characterized by wear, softening, and thinning of the articular cartilage and diminished compliance of the sub-chondral bone (Bijlsma et al., 2011; Felson and Zhang, 1998; Iannone and Lapadula, 2003). The knee is the most prevalent weight-bearing joint prone to the development of this destructive process, with the medial compartment affected nearly 10 times more often than the lateral compartment (Oliveria et al., 1995). Vast evidence supports the role of biomechanical factors in the pathophysiology of this disease (Radin et al., 1991). Abnormal joint loads have been related to the development and progression of the arthritic process (Radin et al., 1991; Roemhildt et al., 2010). Abnormally high knee adduction moments (KAM) have been described in association with medial knee OA (Andriacchi, 1994; Sharma et al., 1998). Elevated KAM has been linked with the progression of knee OA (Miyazaki et al., 2002), and has been recognized as a marker of disease severity (Hurwitz et al., 2002; Sharma et al., 1998). Gait deviations have been reported in individuals suffering from knee OA (Baliunas et al., 2002; Debi et al., 2009; Elbaz et al., 2010; Gok et al., 2002; Hurwitz et al., 2000) and are thought to represent a compensatory protective mechanism intended to reduce stress and range of motion about the injured joint (Debi et al., 2009). With disease progression, altered morphological joint properties diminish the effectiveness of these mechanisms. Moreover, substantial evidence suggests that impairment of the neuromuscular control system and proprioceptive deficits are present in subjects suffering from knee OA and contribute to the load burden by altering joint biomechanics (Hortobagyi et al., 2005; Hurley, 2003; Johansson et al., 2000, Lewek et al., 2005). Several authors stressed the role of these contributions to the pathogenesis of the disease, suggesting that they convey elevated joint stress with higher impact loads and facilitate the development of cartilage degeneration (Sharma et al., 2003; Slemenda et al., 1998). Biomechanical interventions focusing on foot center of pressure (COP) manipulation, agility, and perturbation training have been suggested for the treatment of knee OA (Bar-Ziv et al., 2010; Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/jbiomech www.JBiomech.com Journal of Biomechanics 0021-9290/$ - see front matter & 2011 Published by Elsevier Ltd. doi:10.1016/j.jbiomech.2011.10.017 n Corresponding author at: Biorobotics and Biomechanics Lab (BRML), Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel. Tel.: þ972 52 4262129. E-mail address: amirhaim@gmail.com (A. Haim). Please cite this article as: Haim, A., et al., Reduction in knee adduction moment via non-invasive biomechanical training: A longitudinal gait analysis study. Journal of Biomechanics (2011), doi:10.1016/j.jbiomech.2011.10.017 Journal of Biomechanics ] (]]]]) ]]]–]]]