349Biocompatible materials - LV 308.106
Biocompatible materials 12.12.2011
Non-metallic Materials
Implants for the muscoloskeletal system– Knee endoprosthesis systems
– Problems associated with (polymer) sliding surfaces
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Implants for the Muscoloskeletal SystemKnee Joint Endoprosthesis
SystemsBiofunctionality: load transfer, support and
movement
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Knee Joint
©Mysid
Quadriceps
Oberschenkel-knochen
Gelenk-knorpel
äußerer Gelenkknorrenhinteres Kreuzband
vorderes Kreuzband
Außenband
Wadenbein
Schienbein
Quadriceps-Sehne
Kniescheibe
Innenband
Meniskus
Kniescheiben-band
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Cartilage defectsSurgeons classify defects in the knee cartilage using a grading scale from I (one) to IV (four).
In a grade I tear, the cartilage has a soft spot.
Grade II lesions show minor tears in the surface of the cartilage.
Grade III lesions have deep crevices.
In grade IV lesions, the tear goes all theway to the underlyingbone.
eOrthopod.com
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www.unifr.ch
www.swissklinik.ch
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Knee Joint
Causes for knee joint disease– Leg axis defective position (varus = bow legged O-Beine;
valgus = knock-kneed X-Beine)– Rheumatism– Metabolic diseases
Result– Meniscus damage– Cartilage and bone abrasion
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Knee Endoprosthesis Systems
Constrained knee endoprosthesis– Removal of bigger bone parts– Femoral and tibial parts form a
hinged joint, that no longer allows rotation of the knee
– Functioning ligaments are not necessary
Resurfacing– Removal of damaged cartilage primarily– The knee ligament structures can be kept mostly
Resurfacing prosthesis are more frequently used than constrained ones
www.orthodynamics.de
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Knee Endoprosthesis: Resurfacing Prosthesis
Single-side endoprosthesis:
with replaced inner or outer joint parts
The healthy cartilage and the ligaments are kept.
Double-side endoprosthesis:
a) In the unhinged endoprosthesis (mid) the joint surfaces of the femur and the tibia are replaced. The posterior cruciateligament (PCL) is kept.
b) The hinged (right) endoprosthesis includes an additional spine, thus it does not need the lateral ligaments. The PCL can not be preserved. For stabilising the knee a mortise joint is realised (Posterior Stabilising tibial insert).
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Fixation
Cement-free knee endoprosthesis
Cemented knee endoprosthesis
Hybrid knee endoprosthesis
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Knee Endoprosthesis Mebio®
Femur component(Co-Cr-Mo) Tibia component
(Co-Cr-Mo)
PE Plateau (PE-UHMW)
Patella component(PE-UHMW)
Shape of the joint surface determines movability(rotation, backwards sliding)
Elements for anchorage in the cementStem geometry and texture ensure fixation and rotational stability
www.aap.de
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Knee arthroplasty
M.S. Taljanovic et al., 2003
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Unicompartmental knee prosthesisZimmer® ZUK
Femur component(Co-Cr)
Tibia component(Ti6Al4V)
www.zimmer.ch
PE Plateau (PE-UHMW)
M.S. Taljanovic et al., 2003
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Zimmer® Gender Solutions™ NexGen® High-Flex Knee
www.zimmer.com