Frontal plane knee alignment mediates the effect of frontal plane rearfoot motion on knee joint load distribution during walking in people with medial knee osteoarthritis.

Affiliation

Hunt MA(1), Charlton JM(2), Felson DT(3), Liu A(4), Chapman GJ(5), Graffos A(6), Jones RK(7).
Author information:
(1)Motion Analysis and Biofeedback Laboratory, University of British Columbia: Vancouver, BC, Canada; Department of Physical Therapy, University of British Columbia: Vancouver, BC, Canada. Electronic address: [Email]
(2)Motion Analysis and Biofeedback Laboratory, University of British Columbia: Vancouver, BC, Canada; Graduate Programs in Rehabilitation Sciences, University of British Columbia: Vancouver, BC, Canada. Electronic address: [Email]
(3)Department of Rheumatology, Boston University School of Medicine, Boston, MA, USA; NIHR Manchester Musculoskeletal Biomedical Research Centre, Manchester, UK; Manchester University Hospitals NHS Foundation Trust, Manchester, UK. Electronic address: [Email]
(4)School of Health and Society, University of Salford: Manchester, UK. Electronic address: [Email]
(5)School of Sport and Health Sciences, University of Central Lancashire: Preston, UK. Electronic address: [Email]
(6)Motion Analysis and Biofeedback Laboratory, University of British Columbia: Vancouver, BC, Canada; Graduate Programs in Rehabilitation Sciences, University of British Columbia: Vancouver, BC, Canada. Electronic address: [Email]
(7)School of Health and Society, University of Salford: Manchester, UK. Electronic address: [Email]

Abstract

OBJECTIVE: To examine the nature of differences in the relationship between frontal plane rearfoot kinematics and knee adduction moment (KAM) magnitudes. DESIGN: Cross-sectional study resulting from a combination of overground walking biomechanics data obtained from participants with medial tibiofemoral osteoarthritis at two separate sites. Statistical models were created to examine the relationship between minimum frontal plane rearfoot angle (negative values = eversion) and different measures of the KAM, including examination of confounding, mediation, and effect modification from knee pain, radiographic disease severity, static rearfoot alignment, and frontal plane knee angle. RESULTS: Bivariable relationships between minimum frontal plane rearfoot angle and the KAM showed consistent negative correlations (r = -0.411 to -0.447), indicating higher KAM magnitudes associated with the rearfoot in a more everted position during stance. However, the nature of this relationship appears to be mainly influenced by frontal plane knee kinematics. Specifically, frontal plane knee angle during gait was found to completely mediate the relationship between minimum frontal plane rearfoot angle and the KAM, and was also an effect modifier in this relationship. No other variable significantly altered the relationship. CONCLUSIONS: While there does appear to be a moderate relationship between frontal plane rearfoot angle and the KAM, any differences in the magnitude of this relationship can likely be explained through an examination of frontal plane knee angle during walking. This finding suggests that interventions derived distal to the knee should account for the effect of frontal plane knee angle to have the desired effect on the KAM.