Annie Horng MD, Presenter: Nothing to Disclose

José Raya MSc, Abstract Co-Author: Nothing to Disclose

Monika Zscharn, Abstract Co-Author: Nothing to Disclose

Ulrike Hoehne-Hueckstaedt, Abstract Co-Author: Nothing to Disclose

Ingo Hermanns Dipl Eng, PhD, Abstract Co-Author: Nothing to Disclose

Ulrich Glitsch, Abstract Co-Author: Nothing to Disclose

Rolf Ellegast, Abstract Co-Author: Nothing to Disclose

Maximilian F. Reiser MD, Abstract Co-Author: Nothing to Disclose

Christian Glaser MD, Abstract Co-Author: Nothing to Disclose

To evaluate cartilage deformation in the knee in 3 postures assumed as potential risk factors for work-related osteoarthritis.

MRIs of the knee at 3T were acquired in 10 healthy volunteers before and immediately after kneeling at 90° / squatting / sit on heels for 10 min, as well as after 90 min rest post exercise. At each time point a sagittal 3D-T1-w FLASH-WE-sequence (TR 22ms/TE 9.8ms/FA 15°/resolution 0.3²x1.5mm³/matrix 512²) was acquired. Patellar, femoral and tibial cartilage were segmented and 3D reconstructed. The following volumetric parameters were calculated: volume (vol), bone-cartilage-interface (BCI), mean thickness (mth), voxel based distribution of local cartilage thickness and thickness difference plots. Reproducibility of segmentation was assessed by RMSA in 3 repetitive baseline acquisitions. Statistics were performed by Wilcoxon test.

Reproducibility of segmentation was 1.1% for vol, 0.6% for BCI and 0.7% for mth. No significant change of BCI was found after exercise and after rest. Significant cartilage deformation was found for vol/mth of patellar (4.9/4.7%) and lat. tibial cartilage (2.5/2.5%) after kneeling, for vol of femoral (2.1%), mth of patellar (2.2%) and lat. tibial cartilage (2.2/1.8%) after squatting and for vol/mth of patellar (3,1/2,6%) and femoral cartilage (2.2/1.4%) after sit on heels. Baseline data did not differ from data after resting. Thickness difference plots exhibit pronounced focal cartilage deformation (up to 9%) at caudal patella/centrodorsal lat. tibia after kneeling, caudomedial patella/dorsal femur/anterior tibiae after squatting and caudal patella/dorsal femur/broad lat. tibia after sit on heels.

Cartilage volumetry before/after loading can provide possible in vivo knee joint contact zones for specific activities and may allow assessment of the reversibility of stress induced changes. The findings may be a base for finite element models to calculate stress patterns and help to derive possible preventive measures for labor protection and cartilage graft engineering.

HR-3D-MR-volumetry at 3T provides an approach to understanding magnitude and local distribution of loading dependent cartilage deformation in the different compartments of the knee joint.

Horng, A, Raya, J, Zscharn, M, Hoehne-Hueckstaedt, U, Hermanns, I, Glitsch, U, Ellegast, R, Reiser, M, Glaser, C, Initial Approach of Visualization of in Vivo Deformation Pattern of the Knee Cartilage Using 3 T HR-MRI after Kneeling, Squatting, or Sitting on the Heels.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9008870.html