Modern concepts of knee implants Modern concepts of knee implants Dr. Clemens Menapace Dr. Clemens Menapace FA für Orthopädie und orthop. Chirurgie FA für Orthopädie und orthop. Chirurgie Ritter v. Schwarzstr. 8, Hallein Ritter v. Schwarzstr. 8, Hallein

Director of the Departement for orthopedic and endoskopic joint surgery Ritter v. Schwarzstr Hallein Guggenbichlerstr, Salzburg M.D. Orthopedy and orthopedic surgery ClemensMENAPACE Modern concepts of knee implants Modern concepts of knee implants

Modern concepts of knee implants Director of the Departement for orthopedic and endoscopic joint surgery Ritter v. Schwarzstr Hallein Guggenbichlerstr, Salzburg M.D. Orthopedics and orthopedic surgery ClemensMENAPACE

Modern concepts of knee implants Modern concepts of knee implants Dr. Clemens Menapace Department for orthopedic and endoscopic Department for orthopedic and endoscopic joint surgery

Modern concepts of knee implants Modern concepts of knee implants

Modern concepts of knee implants Orthopedic surgery is getting more and more technically demanding

Modern concepts of knee implants Modern concepts of knee implants Component- design problems Component- design problems Problems with materials Problems with materials complicated biomechanics complicated anatomy of the knee complicated anatomy of the knee Biological complexity Technical complexity Developement of state of the art kneeimplant was impaired by

Modern concepts of knee implants Modern concepts of knee implants Biomechanically the knee contains 3 separate joints Mediallateral Femorotibial joint Femoropatellar joint The knee is a multi-ax system: center of ax-rotation changes during cycle of motion Flexion and Extension is a role- and glide - mechanism because of a negativ (decreasing) condyle-radius causing shear-forces During cycle of motion different combination of ligaments provide stability Complex Biomechanics

Modern concepts of knee implants Complex Biomechanics 3 rotational axes of movement 1 axis with moving center of rotation rol & glide movement (translation- rotation) load-aera decreases in flexion (decreasing fc-radius) patellar biomechanic

Modern concepts of knee implants Modern concepts of knee implants Complex Anatomy

Modern concepts of knee implants In conclusion the Flexion / Extension movement of the knee is not a fixed hinge type system but rather a dynamic role- and glide- mechanism with an endrotation in full extension. Flexion and extension is performed along several axes with dynamic centers of rotation secured statically by changing combinations of ligaments and dynamically by groups/combinations of muscels.

Modern concepts of knee implants Performance-requirements for an efficent kneeimplnat/-endoprothesis Physiological range of motion without undue stress on components Stability Longevity

Modern concepts of knee implants The ultimate goal is to imitate anatomy as close as possible

Modern concepts of knee implants Anatomically correct Decreasing /negativ radius of femurcondyles has to be imitated changing centers of rotation

Modern concepts of knee implants Restore perfect alignement valgusvarus Alignement deficiencies have to be corrected painstakingly to avoid peak-pressure locally

Modern concepts of knee implants preoppostop Planning of proper alignément

Modern concepts of knee implants Restore perfect ligament tension and balance

Modern concepts of knee implants Combination of low friction interface Ceeramics ceramics Ceramics Polyaethylen Polyaethylen Metal Polyaethylen Metal Metal Femur Tibia

Modern concepts of knee implants stabel fixation of components to bone cement Press fit screw fixation

Modern concepts of knee implants Modern concepts of knee implants D e v e l o p m e n t

Modern concepts of knee implants Stoneage of knee-implants

Modern concepts of knee implants GSB-Hinge-Type 1970 semiconstraint Tour de France ?

Modern concepts of knee implants Fixed tbial bearing The Vienna Derby

Modern concepts of knee implants Mobile bearing Back into the future

Modern concepts of knee implants Congruency High contact stress Low contact stress

Modern concepts of knee implants Large contact area reduces contact stress

Modern concepts of knee implants Different qualities of force exacted on a fixed bearing implant

Modern concepts of knee implants Constraint means that shear and torsion forces could be transmitted to fixation interfaces and cause loosening

Modern concepts of knee implants Mobile bearing prevents sheering forces

Modern concepts of knee implants

mobile patellar bearing

Modern concepts of knee implants cemented-noncemented mobile bearing system

Modern concepts of knee implants Revision-surgery

Constraint systems in use for cases with severe bonedefect Tumor-surgery Revison-surgery

Modern concepts of knee implants Revision-surgery with semiconstraint knee - prosthesis after failure of duocondylar implant

Modern concepts of knee implants Semiconstraint implants for cases with sever bonedefect, instability, malalignement

Modern concepts of knee implants Unicondylar implants

Modern concepts of knee implants Unicondylar implants Unicondylar implants

Modern concepts of knee implants

MGII NEXGEN

Modern concepts of knee implants Mobile bearing knee implant

Modern concepts of knee implants Surgical principles of Duocondylar knee implnats

Modern concepts of knee implants Modern concepts of knee implants

Modern concepts of knee implants

Modern concepts of knee implants

Modern concepts of knee implants

Modern concepts of knee implants Defining the resection lines by using a weight bearing total limb X-ray Ahlbäcks desease

Modern concepts of knee implants Modern concepts of knee implants

Modern concepts of knee implants

Modern concepts of knee implants

Modern concepts of knee implants

Modern concepts of knee implants

Modern concepts of knee implants

Modern concepts of knee implants

Modern concepts of knee implants

Modern concepts of knee implants Resect as little as possible and as much as necessary Bonestock is the most valuable resource Stability Revision surgery

Modern concepts of knee implants Modern concepts of knee implants

Modern concepts of knee implants

Modern concepts of knee implants In conclusion, what do we expect from a modern knee implant

Surgical managability Excuse me Doc, can I see your diploma? Managable for the average orthopedic surgeon Modern concepts of knee implants Modern concepts of knee implants

Durability Modern concepts of knee implants Modern concepts of knee implants

Affordability Modern concepts of knee implants Modern concepts of knee implants

Discussion welcomed BILIS you will be answered Modern concepts of knee implants Modern concepts of knee implants

Modern concepts of knee implants