Page 9 - KNEETA

There are several features in the normal knee that make it A medial-pivoting tibial insert is provided in the KNEETA® Knee
stable: the musculature, capsule, collateral ligaments, the ACL, System, designed to reproduce the rotational and translational
and PCL. Nearly 60% of body weight is transferred through the kinematics of the normal knee. On the lateral side there is an
medial pivot side of the knee. The medial pivot side of the tibial arcuate path, which allows 15° of motion around a medial-pivot
is concave in shape and, along with the medial pivot intercondylar point. That pivot point is on the medial pivot side and is provided by a
plateau beminence, acts to prevent anterior translation of the medial spherical concave surface. The anterior lip is designed to prevent
pivot femoral condyle. The opposite is true, however, for the lateral anterior slide, while the posterior lip is designed to replace the
compartment of the knee. This side is convex in shape and, ACL and prevent posterior slide. FIGURE 4
coupled with a “humped” intercondylar eminence, allows arcuate Medial pivot posterior lip
translation. These structures create a knee that is more stable on the replaces ACL and
pivot stops posterior slide
the concept of medial-pivot kinematics. FIGURE 3

Lateral meniscal
path allows for 15°
A of motion
Medial pivot meniscal
FIGURE 4 | Medial- Medial pivot anterior lip replaces “socket” provides
Pivot Insert PCL and stops anterior slide stability

B C D

FIGURE 5 | The KNEETA®
femur features spheri-
Medial pivot meniscus cal femoral condyles
Lateral meniscus and concave surface
allows motion provide stability
PCL stops
anterior slide
ACL stops
posterior slide FIGURE 3 | Superior view of the tibial plateau

KNEETA FIGURE 6
The curvature values for each femoral implant were chosen from a detailed analysis of 130 cadaveric femora performed by Dr D. Blaha.

6 The KNEETA® Medial-Pivot Total Knee also matches the sagittal radius with the radius in the
coronal plane to create the partial sphere of the femoral components. FIGURE 5
7
In the sagittal plane the femoral component also features a smaller closing radius which has been shown to increase range of motion. FIGURE 7
To further increase range of motion, the shape of the femoral component is complemented by the anterior stability of the KNEETA®

Medial-Pivot Total tibial inserts. These components provide a robust anterior lip which maintains the femoral component in the posterior third
of the articular surface. FIGURE 8 1
REFERENCES
1.
the normal human knee. Clin Orthop Relat
Res. 2003;410:69-81.
2. Schmidt R. Fluoroscopic analyses of cruciate
FIGURE 8 | Femoral retaining and medial pivot knee implants.
Clin Orthop Relat Res. 2003;410:139-147.
Closing Radius position of KNEETA® 3. Freeman M. The movement of the normal
Medial-Pivot Total Knee
90˚ tibiofemoral joint. J Biomechanics.
2005;38:197-208.
4. Pinskerova V. Knee imaging study sheds
60˚ Today. 1999.
5. Freeman. The movement of the knee studied
30˚ by magnetic resonance imaging. Clin Orthop
0˚ 1/3 A-P
FIGURE 6 | Constant radius FIGURE 7 | Smaller A-P Relat Res. 2003;410:35-43.
closing radius 6. Blaha JD. Using the transepicondylar axis to
part of the femur. JBJS 2002; 84:S48-55.
7. Iwaki et al, JBJS 82-B, n°8 (2000): 1189-95
SUNTEK KNEETA R
Medical Devices
and Electronic
Products Trade Co. KNEETA® Medial-Pivot Knee System Total Knee system
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