Page 18 - KNEETA

Shown in FIGURE 5, the following points should maximize the The “ball-in-socket” has substantial clinical history. Mid-term
clinical follow-up of the KNEETA® Pivot Total Knee System indicated
bone on the cut surfaces of the lateral and medial pivot femoral condyles, 96.9% survivorship at ten years. Further comments from an
19
KNEETA® survivorship study at 8 years of follow up indicated
choosing a design with high-projecting posterior condyles that have all their patients were “objectively” stable at mid-term showing a
KNEETA Pivot Total
clinical outcome scores.
20
comparable to standard PS knee designs. 17
Multiple publications have supported
two fundamental conclusions:

Conventional knee replacements do not
Large Posterior Posterior Contact Higher Tibial
Point Location Slope Angle
AND
FIGURE 5
The normal knee permits more posterior
translation of the lateral compartment
1,5-8

Posterior Condylar Small Posterior Central Contact Lower Tibial
Osteophytes Point Location Slope Angle
FIGURE 6 |

Another important factor in the knee kinematics is to maintain
REFERENCES
of the “ball-in-socket” philosophy. The articular geometry of all 1.
Relat Res. 2003;410:69-81.
KNEETA® Medial-Pivot Total Knee System tibial inserts incorporates a 2. Freeman MAR. The movement of the normal tibiofemoral joint. J Biomechanics.
“socket” to prevent anterior translation of the femur. The condyles 2005;38:197-208.
of all KNEETA® Medial-Pivot Total Knee System femoral implants is a 3.
sphere (ball) to ensure the extension geometry is identical to the and weight-bearing conditions. J Arthroplasty. 1998;13(7):748-52.
4.
Orthop Relat Res. 2003;410:114-21.
5.
In contemporary designs, contact areas often decrease with concave tibial joint surface. J Orthop Res. 2000;18:856-64.
6. Banks S. In vivo kinematics of cruciate-retaining and –substituting knee
arthroplasties. J Arthroplasty. 1997;12(3):297-303.
curvature. Because of the constant radius of the femoral 7. Uvehammer J. In vivo kinematics of total knee arthroplasty: concave vs. posterior-
component, contact areas with the KNEETA® tibial inserts remain stabilized tibial joint surface. JBJS. 2000;82(4):499-505.
18 8. Most E. Femoral rollback after cruciate-retaining and –stabilizing total knee
arthroplasty. Clin Orthop Relat Res. 2003;410:101-13.
9. Blaha J. The rationale for a total knee implant that confers anteroposterior stability
The KNEETA® Medial-Pivot Total Knee System was designed to throughout range of motion. J Arthroplasty. 2004;1 (4):22-26.
FIGURE 10 10. Scott W. Surgery of the knee, Fourth Edition, Volume 1. 2006.
11. Schmidt R et al “Fluoroscopic analyses of cruciate-retaining and medial-pivot knee
ENHANCED TIBIOFEMORAL CONTACT AREA 18 implants” COOR, 410: 139-147
CONTACT AREA (mm ) 2 12.
arthroplasties. Clin Orthop Relat Res. 2003;410:131-8.
13.
0° prostheses. J Arthroplasty. 2009;24(5):674-80.
14.
total knee prostheses: a prospective randomized study. JBJS. 2009;91:1874-81.
15. Suggs JF. Patient function after a posterior stabilizing total knee arthroplasty:
cam-post engagement and knee kinematics. Knee Surg Sports Traumatol Arthrosc.
60° FIGURE 10 | Contact area comparison 16. 2008;16:290-6.
KNEETA® Medial-Pivot arthroplasty. JBJS. 2002;84(1):50-3.
GENESIS® Standard 17. Shakespeare et al “Flexion after total knee replacement. A comparison between the
LCS® medial-pivot knee and a posterior stabilised implant” The Knee 13 (2006): 371-73
Natural® Ultra Congruent 18. MicroPort Orthopedics Engineering Report, ER97-0059
90° PFC® Curved 19. 2010 Danish Knee Arthroplasty Register
20. Karachalios T. A mid-term clinical outcome study of the KNEETA® Medial- Pivot Total Knee
arthroplasty. The Knee. 2009;16(6):484-8
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Medical Devices
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18 Products Trade Co. KNEETA® Medial-Pivot Knee System Total Knee system