Medacta Corporate

The science of
movement

The Cinétique is a rotating platform total knee replacement prosthesis, based on a proven concept, and has been conceived by a group of experienced surgeons, with two main goals: the respect of anatomy and an optimal ligament balance, thanks to an accurate and reproducible surgical technique.

  1. Asymmetric tibial tray ensures perfect coverage of the tibial resection, minimising the risk of overhanging and sinking
  2. Mirror polished tibial tray minimises the risk of backside wear
  3. Deep anatomic trochlea optimises the patellar tracking, reducing stress on patellar tendon and the risk of patella dislocation
  4. J-curved sagittal profile allows more natural knee kinematics, improves knee flexion and promotes rollback of the femoral component

STANDARD FEMORAL COMPONENT

6 sizes
Anatomical: left and right
Material: Cobalt-Chrome (Co-Cr-Mo ISO 5832-4)
Cemented: 0.5 mm deep pockets
Cementless: CoCr beads + Hydroxyapatite double coating
Antiallergic TiNb coated version (cemented only)

TIBIAL TRAY

7 sizes
Anatomical: left and right
Material: Cobalt-Chrome (Co-Cr-Mo ISO 5832-4)
Cemented: 0.5 mm deep pockets
Cementless: CoCr beads + Hydroxyapatite double coating
Antiallergic TiNb coated version (cemented only)

 

STANDARD INSERT (CRUCIATE RETAINING)

6 sizes
5 thicknesses: 7, 9, 11, 13, 15 mm
Rotating platform with universal cone
Machined Ultra High Molecular Weight Polyethylene (UHMWPE ISO 5834-2)

 

ULTRACONGRUENT INSERT

6 sizes
5 thicknesses : 7, 9, 11, 13, 15 mm
Rotating platform with universal cone
Machined Ultra High Molecular Weight Polyethylene (UHMWPE ISO 5834-2)

 

RESURFACING PATELLA

Anatomic shape, three fixation pegs
3 sizes
Machined Ultra High Molecular Weight Polyethylene (UHMWPE ISO 5834-2)
Cemented

 

RESURFACING METAL BACK MOBILE PATELLA

Asymmetric shape, three fixation pegs
3 sizes
Machined Ultra High Molecular Weight Polyethylene (UHMWPE ISO 5834-2) and Co-Cr-Mo (ISO 5832-4)
Cemented
Cementless: CoCr beads + Hydroxyapatite double coating
Antiallergic TiNb coated version (cemented only)

 

INSET PATELLA

Symmetric shape,  one central fixation peg
3 sizes
Machined Ultra High Molecular Weight Polyethylene (UHMWPE ISO 5834-2)
Cemented

 

FEMORAL COMPONENT

IMPROVED KINEMATICS
Optimised A/P and M/L ratio to decrease the tension on the patella
6°oriented trochlear groove to increase the femur-patella stability

Femoral multiradius sagittal profle (J-curved): two radii of curvature, the smallest one on the posterior condyles, to achieve a higher flexion  and promote the natural roll back.

FLEXION-FRIENDLY IMPLANT
The 10° sloped distal cut and the 7° slopped suggested tibial cut allow the Cinétique to be a flexion-friendly implant.

POLYETHYLENE INSERT

MATERIAL
Medacta Cinetique tibial inserts do not undergo any irradiation or thermal process that can affect the mechanical properties and the oxidative stability of the material. This ensures the best maintenance of mechanical properties which is crucial to reduce the delamination process [1], the main cause of polyethylene failure in total knee arthroplasty. [2]

*The value refers to a non-irradiated polyethylene with characteristics similar to those of GMK inserts polyethylene.

Figure 1: Modulus (defined as the ratio of tensile stress to tensile strain) for non-irradiated and cross-linked polyethylene. Subsequent melt stabilisation for cross-linked polyethylene was performed at 170°C. Adapted from Baker et al. [3].

*The value refers to a non-irradiated polyethylene with characteristics similar to those of GMK inserts polyethylene.

Figure 2: Yield stress (MPa) for non-irradiated and cross-linked polyethylene. Subsequent melt stabilisation for cross-linked polyethylene was performed at 150°C. Adapted from Muratoglu et al. [4].

*The value refers to a non-irradiated polyethylene with characteristics similar to those of GMK inserts polyethylene.

Figure 3: Ultimate tensile strength (MPa) for non-irradiated and cross-linked polyethylene. Subsequent melt stabilisation for cross-linked polyethylene was performed at 150°C. Adapted from Muratoglu et al. [4].

 

Learn more about Medacta polyethylene: Polyethylene in TKA: Do we really need cross-linked polyethylene?, MORE Journal Vol. 1 May 2011. [5]

ACCURATE LIGAMENT BALANCE

The Cinétique instrumentation is based on a proven concept and has been developed to achieve accuracy in every step:

  • Implant sizing.
  • Cuts execution.
  • Ligaments balance.

Purposely designed instruments allow to perform multiple checks at different stages of the procedure, in order to reach the final goal of equivalent flexion and extension gaps, based on the natural tension of the ligaments.

Cinetique MIS: a  specific version of the instruments is available for muscle sparing surgical approaches.

DESIGN RATIONALE
[1] Ries M D, “Highly Cross-Linked Polyethylene. The Debate is Over-In Opposition”, The Journal of Arthroplasty, 20:59-62, 2005.
[2] Kondo et al. “Arthroscopy for evaluation of polyethylene wear after total knee arthroplasty”, J Orthop Sci, 13:433-437, 2008. Orthop Sci, 13:433-437, 2008
[3] Baker et al., “The effects of degree of Crosslinking on the fatigue crack initiation and propagation resistane of orthopedic-grade polyethylene”, J Biomed Mater Res A, 66(1):146-54, 2002.
[4] Muratoglu et al., “Unified wear model for highly crosslinked ultra-high molecular weight polyethylenes (UHMWPE)”, Biomaterials, 20:1463-70, 1999.
[5] Polyethylene in TKA: Do we really need cross-linked polyethylene?, MORE Journal Vol. 1 May 2011

CLINICAL  STUDIES
[6] Neue Knieendoprothese mit rotierender Plattform E. Shwameis JATROS Orthopädie 3/2004; pag. 22-24
[7] S. Amedy,  Internal report: comparative study among cemented, cementless and HA coated implant versions. Clinical and radiological evaluation up to 1 year.
[8] Elia , Résultats à court terme de la prothèse totale du genou Cinétique. A propos de 41 cas suivis en 2005.
[9] Computer-Assisted Surgery with fastNav System for Knee Arthroplasty Techniques in Knee Surgery, 2009;8(3):201-210
[10] Reprise de prothèse unicompartimentale fémorotibiale par une prothèse totale du genou CINETIQUE MEDACTA. Résultats d’une série de 17 cas. May 2011

The Cinétique instrumentation is fully compatible with the iMNS Medacta Navigation System.

In addition, the Cinétique MIS instrumentation provided allows the surgeon to perform a Computer Assisted muscle sparing approach in order to combine the accuracy of navigation and the benefits of minimally invasive surgery for the patient.