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ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

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INVESTIGATING CHANGES IN JOINT LOADING FOLLOWING HIGH<br />

TIBIAL OSTEOTOMY<br />

1. ABSTRACT<br />

G.M. Whatling 1 , D. Watling 2 , C Wilson 3 and C.A. Holt 4<br />

High tibial osteotomy (HTO) surgery is performed as a treatment for medial<br />

compartment knee osteoarthritis (OA), where the joint is realigned to redistribute<br />

loading and relieve pain. Changes in joint alignment intend to shift the location of force<br />

transmission and the mechanical stresses from the diseased medial to the healthy lateral<br />

knee compartment. The aim of this study is to identify the efficacy of HTO surgery in<br />

modifying knee loading. Peak external knee adduction moment (EKAM) and knee<br />

adduction angular impulse (KAAI) provide useful information on medial compartment<br />

loading and disease severity. In this study, KAM and KAAI measured during level gait<br />

were investigated from 10 patients pre HTO surgery and 6 patients post HTO surgery<br />

using three-dimensional motion analysis and biomechanical modeling using Visual3D<br />

(C-motion. Inc). Two patient reported outcomes (The Knee Outcome Survey and<br />

Oxford Knee Scores) were also completed by each patient. A statistically significant<br />

reduction in EKAM, KAAI was calculated post-HTO surgery, indicating decreased load<br />

through the medial knee compartment. There was also a statistically significant increase<br />

in the two patient scores indicating improved patient perceived function. A decrease in<br />

EKAM and KAAI for the contra-lateral non affected limb was identified, though this<br />

was not statistically significant.<br />

2. INTRODUCTION<br />

Osteoarthritis (OA) affects 8 million people in the UK [1]. It is a degenerative joint<br />

disease most prevalent in the medial compartment, where articular cartilage deteriorates,<br />

causing joint stiffness and pain. Increasing evidence supports the hypothesis that joint<br />

degeneration is driven by biomechanical forces and the pathological response by the<br />

surrounding tissues [2]. The knee joint bears up to 2.5 times body weight during level<br />

gait [3]. The ground reaction force (GRF) passes medially to the joint centre, resulting<br />

in the medial compartment experiencing the greatest proportion of the load [4,5]. Thus,<br />

knee OA predominantly affects the medial compartment leading to loss of cartilage,<br />

change in the subchondral bone, a reduction in joint space and consequently a varus<br />

deformity [6]. Varus deformity results in increased loads in the medial compartment.<br />

Thus patients with varus knee alignment are prone to developing more severe medial<br />

compartment OA unless the mechanics are corrected [7,8].<br />

1<br />

Academic Fellow, School of Engineering, <strong>Cardiff</strong> <strong>University</strong>, CF243AA, Wales, UK<br />

2<br />

PhD Student, School of Engineering, <strong>Cardiff</strong> <strong>University</strong>, CF243AA, Wales, UK<br />

3<br />

Consultant Orthopaedic Surgeon, <strong>University</strong> Hospital of Wales, <strong>Cardiff</strong><br />

4<br />

Reader, School of Engineering, <strong>Cardiff</strong> <strong>University</strong>, CF24 3AA, Wales, UK<br />

1-4<br />

Arthritis Research UK Biomechanics and Bioengineering Centre, <strong>Cardiff</strong> <strong>University</strong>, Wales, UK

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