Single Radius
Studies of kinematics and biomechanics1 have identified a constant radius in natural knee motion centered about the transepicondylar axis.
The Triathlon TS knee system is designed with a patented single radius. Centering the radius of curvature about the transepicondylar axis provides ligament isometry, not only in full extension and 90 degrees of flexion, but through the entire range of motion. The single radius centered about the epicaondylar axis reproduces natural knee movements designed to minimize the quadriceps forces required for extension thereby maximizing muscle efficiency.1-3
1. Hollister AM, Jatana S, Singh AK, SullivanWW, Lupichuk AG. The axes of rotation of the knee. Orthopaedic Laboratory, Harbor-UCLA Medical Center, Torrance. Clin Orthop. 1993 May;(290):259-68.
2. Freeman MAR, Pinskerova V, Hill PF, Vedi V,Williams A, Iwaki H, Kadoya Y, Kobayashi A, Nakagawa S, Sakamoto H, Todo S, Yamano Y, Brandsson S, Karrholm J. Tibiofemoral movement – Studies in the cadaveric and living knee using MRI, dissection and RSA; British Editorial Society of Bone and Joint Surgery, 2001.
3. Churchill DL, Incavo SJ, Johnson CC, Beynnon BD. The transepicondylar axis approximates the optimal flexion axis of the knee. Clin Orthop. 1998 Nov;(356):111-8.
Motion:
Stryker Test Data RD-03-041 and RD-04-027
Better Fit:
Hitt, Kirby, et al. anthropometric Measurements for the Human Knee. Correlation to the Sizing of Current knee Arthroplasty Systems JBJS Vol. 85-A Sup. 4, 2003
Wear:
Stryker Orthopaedics Test Report RD-06-013.