Conservative surgical treatments for osteoarthritis: A Finite … UK... · 2011-11-15 ·...
Transcript of Conservative surgical treatments for osteoarthritis: A Finite … UK... · 2011-11-15 ·...
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Conservative surgical treatments for
osteoarthritis: A Finite Element Study
Diagarajen Carpanen, BEng (Hons), Franziska Reisse, BEng(Hons), Howard
Hillstrom, PhD, Kevin Cheah, FRCS, Rob Walker, PhD, Rajshree Mootanah,
PhD
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Introduction
• Osteoarthritis (OA) : degenerative disease of all the tissues in
the di-arthrodial joint leading to pain, limited mobility and joint
deformation. (Coggon, et al., 2000)
• 14.1% of men & 22.8% of women over 45 years show symptoms
of OA of the knee. (Valkenburg, 1980)
• OA costs £12 billion to the NHS and $185.5 billion to the United
States annually. (Mathers, at al., 2006)
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Common Causes of Knee Osteoarthritis
• Knee malalignment – 4x more prone to
develop OA. (Sharma, L., 2001)
• Joint injury - a torn meniscus or
ligament which can result from a twisting
injury ( football, skiing ). (Englund, et al., 2003)
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Knee Mal-alignment
5 degrees of varus mal-alignment
=> 70% - 90% increase in
compressive loading in knee joint
=>resulting in OA
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Meniscus & Meniscal Tears
Functions: Load bearing
and stabilisation
Four Basic Tears:
I - longitudinal;
II - horizontal;
III - oblique;
IV - radial (Source: Operative Orthopaedics, 2007)
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• High tibial osteotomy (HTO) is a surgery aiming to relieve pain and
restore high-level function in active patients by re-aligning the lower limb
and lowering the contact stress in the knee joint.
• Partial meniscectomy is an arthroscopic surgical procedure commonly
performed to resect the injured part of the meniscus, to relieve
symptoms and restore knee function.
High Tibial Osteotomy &
Partial Meniscectomy
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Gap in Knowledge
•The underlying link between malalignment and stress in the knee
compartment is not well understood. Also surgical realignment
outcomes by HTO have been unpredictable for unknown reasons
•Effects of resecting specific sizes and locations of meniscus on
knee joint contact stresses is not clear.
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Methodology
CT scan /MRI
3- MATICS
Remesh ModuleSmooth surfaces,
Non-Manifold
assembly, meshing
MIMICS Modules
Image
processing,
generation of 3D
structure
FEA Package
Conversion of
mesh to solid
part & FEA
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GE's Light Speed Plus Scanner (Courtesy of GE
Medical Systems)
• Cadaveric knee joint was CT-scanned,
using a GE Medical Systems CT-scanner.
• Slice thickness: 0.49mm
• Pixel size: 0.6 mm
CT Scan of the Knee
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MRI of the Knee
GE Healthcare's Signa Excite HD 3T system
• MRI data acquired using 3T scanning systems.
• A combined 3D spoiled gradient recalled echo
(SPGR) and XETA sequence were used to create
accurate 3D models of the cartilage and meniscus,
respectively.(Mootanah et al., 2011)
• In-plane resolution: 0.29 mm x 0.29 mm.
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3D Knee Model Development
CT Image MRI scan
Femur
FibulaTibia
Femoral Cartilage
Meniscus
Tibial Cartilage
Bones Soft Tissues
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Image Registration of Osseous &
Soft Tissues
• 3D MRI model was registered to the 3D CT
model.
• Point and global registration techniques were
employed, using the minimum RMS error.
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Non-manifold Assembly (NMA)
• NMA algorithm permits elimination of sections between surfaces.
• This ensures that a common border is calculated.
• Finally a volume mesh for NMA was created.
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Preliminary FEA Studies
• Healthy knee
• Knee with a total
meniscectomy
• Knee with malalignment
Material Properties
employed
Young’s
Modulus
[MPa]
Poisson’s Ratio
Bones 1000 0.3
Cartilage 50 0.45
Meniscus 112 0.45
Ligaments 400 0.45
Source: Kubicek, M. and Florian,Z., 2009
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Contact Definitions
Labelling Contact Pair
1 Tibial Cartilage - Meniscus
2 Femoral Cartilage - Meniscus
3 Femoral Cartilage - Tibial Cartilage
• Contact Surfaces are allowed to touch but not penetrate.
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Boundary Conditions
Solve for stress at static equilibrium to
simulate standing on one leg:
1. Fix the distal tibia and fibula.
2. Apply axial load at the proximal femur .
3. Set constraints :
• Translation free in vertical direction only
• Flex/ext constrained to sagittal plane
• Other rotational degrees of freedom free
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Preliminary Results
Intact knee ~ 2.6 Mpa
Total Meniscectomy ~ 4.9 MPa
Malaligned Knee ~ 4.2 MPa
P: posterior
A: anterior
M: medial
L: lateral
P
L
A
M
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Conclusion
Preliminary findings show
• the importance of the meniscus in reducing knee joint
contact stresses.
• that malaligned knees are subjected to high stress levels
which indicates the importance of understanding realigning
(e.g. HTO) surgical techniques.
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Further Works
• Simulation of HTOs and partial meniscectomies.
• Model cartilages and meniscus as visco-elastic materials.
• Model ligaments as hyper-elastic.
• Sensitivity analysis.
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Coggon D, Croft P, Kellingray S, Barrett D, McLaren M, Cooper C. Occupational physical activities and osteoarthritis of the knee.
ArthritisRheum 2000; 43: 1443-9.
Englund, M., Roos, E. and Lohmander, L., 2003. Impact of type of meniscal tear on radiographic and symptomatic knee osteoarthritis: A
sixteen‐year followup of meniscectomy with matched controls. Arthritis & Rheumatism, 48(8), pp. 2178-2187.
Mathers CD, Loncar D. Projections of global mortality and burden of disease from 2002 to 2030. PLoS Med. 2006; 3:e442.
Mootanah, R., Imhauser, C., Koff, M., Potter, H. and Hillstrom, H., 2011. MRI Sequence Influences Geometrical Interpretation of Osseous
Tissues, Orthopaedic Research Society 2011.
Sharma, L. et al., The role of knee alignment in disease progression and functional decline in knee osteoarthritis. JAMA. 286 (2), 2001
Valkenburg H. Clinical versus radiological osteoarthritis in the general population. In: Peyron J (ed). Epidemiology of Osteoarthritis. Paris:
Ciba-Geigy, 1980:53-58.
References
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Acknowledgement
• Supervisory Team: Dr Rajshree Mootanah, Dr Rob
Walker, Professor Kevin Cheah, Dr Howard Hillstrom
• The Higher Education Funding Council for England
• The Chelmsford Medical Education and Research Trust
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For more information, please visit
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