High tibial osteotomy results in improved frontal plane knee moments, gait patterns and patient-reported outcomes

Gemma M Whatling,Chris Wilson,Paul R Biggs,Andrew Metcalfe,David W Elson,Cathy Holt

doi:10.1007/s00167-019-05644-7

Abstract

PurposeThe purpose of this study was to quantify changes in knee loading in the three clinical planes, compensatory gait adaptations and patient-reported outcome measures (PROMS) resulting from opening wedge high tibial osteotomy (HTO).MethodsGait analysis was performed on 18 participants (19 knees) with medial osteoarthritis (OA) and varus alignment pre- and post-HTO, along with 18 controls, to calculate temporal, kinematic and kinetic measures. Oxford Knee Score, Knee Outcome Survey and visual analogue pain scores were collected. Paired and independent sample tests identified changes following surgery and deviations from controls.ResultsHTO restored frontal and transverse plane knee joint loading to that of the control group, while reductions remained in the sagittal plane. Elevated frontal plane trunk sway (p = 0.031) and reduced gait speed (p = 0.042), adopted as compensatory gait changes pre-HTO, were corrected by the surgery. PROMs significantly improved (p ≤ 0.002). Centre of pressure (COP) was lateralised relative to the knee post-HTO (p < 0.001). Energy absorbed in the sagittal plane significantly increased post-HTO (p = 0.007), whilst work done in the transverse plane reduced (p ≤ 0.008). Pre-operative gait deviations from the control group that were retained post-HTO included smaller sagittal (p = 0.003) knee range of motion during gait, greater stance duration (p = 0.008) and altered COP location (anterior to the knee) in early stance (p = 0.025).ConclusionsHTO surgery restored frontal and transverse plane knee loading to normal levels and improved PROMs. Gait adaptations known to reduce knee loading employed pre-HTO were not retained post-HTO. Some gait features were found to differ between post-HTO subjects and controls.Level of evidenceII

Highlights

MethodsMedial knee osteoarthritis (OA) and associated varus alignment alters knee loading and gait patterns
Pre-High tibial osteotomy (HTO), the Knee Adduction Angular Impulse (KAAI) calculated across the entirety of stance was significantly higher compared to levels found in the control group (p < 0.001); reducing by 41% (p < 0.001) to become ns compared to controls post-HTO
The reduction in pain is important to consider in more detail in future work as this may contribute to the improvement in mechanisms employed pre-HTO to reduce loading

Summary

Introduction

MethodsMedial knee osteoarthritis (OA) and associated varus alignment alters knee loading and gait patterns. During the stance phase of gait, the ground reaction force (GRF) passes medially to the knee joint centre and the medial compartment bears the greatest proportion of load [2, 35]. This is exacerbated by varus knee deformity where patients are prone to develop more severe OA if the mechanics are not corrected [20, 34], evidenced by an increased risk of medial compartment joint space narrowing, osteophytes [36] and increased rate of medial tibial cartilage volume loss [37] in people with varus deformity. Opening wedge HTO reduces an initially elevated peak EKAM to a level lower than that observed in control subjects [6, 7, 14, 26, 27, 31, 33]

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