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

vivo menisco-tibial kinematics during passive knee flexion iii) Investigate the effects of
axial load on meniscal kinematics during flexion and iv) Investigate meniscal
translations with transverse plane TFJ motion. It is hypothesized that the medial and
lateral menisci translate posteriorly with flexion and that the lateral meniscus is more
mobile than the medial due to ligament constraints. Furthermore it is hypothesized that
introducing axial load to the lower limbs will increase posterior translation of both
menisci. Internal rotation of the tibia will lead to increased posterior translation of the
medial meniscus relative to the lateral and increased posterior translation of the lateral
meniscus with external rotation of the tibia.
3. METHODS
One healthy volunteer, without history of pain or pathology to the lower limbs and free
from any other musculoskeletal or neurological condition which may affect knee joint
kinematics was evaluated in this study. Age, weight and height were 25 years, 55kg and
1.60m respectively. The recruitment of the healthy volunteer was approved by the
Research Ethics Committee for Wales and informed, written consent was obtained prior
to participation.
MRI was used to measure the kinematics of the medial and lateral menisci of the
dominant knee relative to the tibia during loaded and unloaded test conditions. The
volunteer was asked to lie supine while a series of 3D MRI images were acquired using
a 3.0T closed bore MRI (Signa HD-xt 3.0T, GE Medical Systems, USA.) and a Flexi-
Coil positioned around the knee. Each scan uses a FIESTA-C sequence approximately 5
minutes long, with a voxel resolution of 0.390mm x 0.390mm x 1.000mm. MR images
were acquired with the knee in a relaxed extended position and then passively
positioned at approximately 25º and 50º knee flexion. The volunteer was then asked to
lie prone and MR images were acquired with the knee in deep flexion, at approximately
130º knee flexion.
The same MRI scanner and imaging sequence were used to image the loaded knee.
Loaded scans were acquired as the volunteer resisted a 200N load attached to a custom
MRI compatible loading device similar to the design of [8]. The volunteer performed a
static supine leg press within the MRI field so that a force is produced longitudinally up
the lower limb. The knee was positioned at full extension and approximately 25 degrees
flexion during loading. Additional scans were acquired as the knee was internally and
externally rotated whilst maintaining 25 degrees knee flexion. Voxel resolution was
reduced from the unloaded scans to 0.625mm x 0.625mm x 0.800mm.
ScanIP software (Simpleware Ltd, UK) was used to create 3D models of both menisci
and the tibia by segmenting each structure from MR scan data. The 3D positions of each
menisci relative to the tibia was investigated. Rhinocerous software (Robert Mcneel and
Associates, USA) was used to create a tibial local co-ordinate system, defined using the
methodology of [9]. Meniscal motion is described by the co-ordinate position of the
meniscus centroid relative to the tibia local co-ordinate system. 3D meniscal translations
are also represented visually by superimposing the 3D meniscus and tibia models
created using ScanIP software (Simpleware Ltd, UK) of the test scan on to that of the
3D models created from neutral position scans using Rhinocerous software (Robert
Mcneel and Associates, USA).