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

QUANTIFICATION OF 3D, IN-VIVO MENISCAL BIOMECHANICS
DURING LOAD BEARING IN CLOSED BORE MRI.
1. ABSTRACT
D. Watling 1 , Dr. G. Whatling 2 and Dr. C. Holt 3
The objectives of this study were to assess the feasibility of imaging the knee during invivo
axial joint loading in a closed bore Magnetic Resonance Imaging (MRI) scanner
and quantify meniscal translations due to tibio-femoral rotations. Novel, 3D, high
resolution MRI sequences and a custom MRI compatible loading device were used to
image the in-vivo knee during flexion and during transverse rotations, both passively
and under loaded conditions. 3D positions of medial and lateral menisci relative to the
tibia were quantified using MR image segmentation and image registration techniques.
The feasibility of high resolution imaging of the tibio-femoral joint and menisci during
loading from which 3D in-vivo menisco-tibial kinematics can be quantified has been
demonstrated. The medial and lateral menisci appear equally mobile in the posterior
direction, translating by a maximum of 10.6mm and 9.2mm respectively. The lateral
meniscus rotates around its anterior horn while the medial meniscus rotates around its
posterior horn during knee flexion. This appears to be a mechanism working in
conjunction with the ACL to resist posterior motion of the femur relative to the tibia
during knee flexion. Axial load bearing and transverse plane knee rotations introduce
large changes in meniscal displacement and are therefore important considerations in
the assessment of meniscal pathology and treatment in future studies.
2. INTRODUCTION
The menisci are fibrocartilagenous structures, located between the femur and tibia.
Menisci are important for load transmission, shock absorption, proprioception, joint
stability and increasing joint lubrication. Damage or pathology to the menisci
compromises these important functions leading to restricted joint motion, pain and a
high likelihood further degenerative changes in the joint such as osteoarthritis (OA) [1].
In-vitro studies have shown the menisci translate relative to the tibia, increasing tibiofemoral
joint (TFJ) congruency, decreasing contact stresses while also protecting
themselves from secondary pathology [2]. Meniscal tears are widely recognised as a
risk factor for OA and commonly occur during twisting or squatting movements [3].
The understanding of in-vivo meniscal biomechanics, particularly during these loading
and movement conditions, is poor however. Magnetic Resonance Imaging (MRI) has
previously been used to investigate in-vivo meniscal translations but these studies are
limited to evaluating single 2D MR slices and do not consider 3D movements [4] [5],
low resolution imaging [4-6] or do not consider joint loading [7]. Furthermore, no study
has investigated meniscal translation with transverse plane TFJ rotations during in-vivo
loading.
The purpose of this study is to: i) Assess the feasibility of high resolution 3D MR
imaging of the knee during joint loading in a closed bore scanner, ii) Quantify 3D in-