Implant Malposition Resulting in Early Failures
- Concerns with UKA are early failure of the femoral or tibial components.
- The main cause of early failure is malpositioning of components with overcorrection or undercorrection of limb alignment.
–Mariani EM, Bourne MH, Jackson RT, Jackson ST, Jones P. Early failure of unicompartmental knee arthroplasty. J Arthroplasty. 2007 Sep;22(6 Suppl 2):81–4.
–Furnes O, Espehaug B, Lie SA, Vollset SE, Engesaeter LB, Havelin LI. Failure mechanisms after unicompartmental and tricompartmental primary knee replacement with cement. J Bone Joint Surg Am. 2007 Mar;89(3):519–25.
Failure of UKA
Tibial Component Malalignment
- Coronal malalignment of the tibial component beyond 3° predisposed to failure
––Swienckowski J, Page BJ. Medial unicompartmental arthroplasty of the knee. Use of the L-cut and comparison with the tibial inset method. Clin Orthop Relat Res. 1989 Feb;(239):161–7.
Femur Component Malalignment
- Malalignment of the femoral component has been found to cause femoral fracture, patellar impingement and tibial component loosening.
–Sandborn PM, Cook SD, Kester MA, Haddad RJ Jr. Fatigue failure of the femoral component of a unicompartmental knee. Clin Orthop. 1987 Sep;(222):249–54.
–Assor M, Aubaniac JM. Influence of rotatory malposition of femoral implant in failure of unicompartmental medial knee prosthesis [in French]. Rev Chir Orthop Reparatrice Appar Mot. 2006 Sep;92(5):473–84.
Excessive Posterior Slope
- Excessive posterior slope (>7°) of the tibial component has been linked to tibial component loosening, anterior cruciate ligament (ACL) rupture and abnormal stress forces on the periprosthetic bone.
–Hernigou P, Deschamps G. Posterior slope of the tibial implant and the outcome of unicompartmental knee arthroplasty. J Bone Joint Surg Am. 2004 Mar;86(3):506–11.
– Sawatari T, Tsumura H, Iesaka K, Furushiro Y, Torisu T. Three-dimensional finite element analysis of unicompartmental knee arthroplasty—the influence of tibial component inclination. J Orthop Res. 2005 May;23(3):549–54.
Comments or questions are welcome.