Meniscal-Bearing Total Knee Arthroplasty

Abstract

Human knee joint replacements have been developed with specific bioengineering requirements to provide near-normal kinematics, maintain fixation, and minimize wear. A mechanical solution to the bearing overload problem that causes excessive wear has been to use more congruent meniscal-bearing surfaces1,2,3,4 to lower the contact stresses below 10 MPa,5 which is reported as the maximum permissible compressive stress limit of ultrahigh-molecular-weight (UHMW) polyethylene. Lowering contact stresses to within the reported medical load limit of 5 MPa6 while allowing kinematically acceptable motion provides a meniscal-bearing surface that is resistant to fatigue wear and demonstrates normal abrasive wear behavior over a 10-year period as seen in both simulator and retrieval studies.2,7,8,9,10 (Figs. 10.1 and 10.2). The first complete systems approach to total knee replacement using meniscal bearings was developed at the New Jersey Medical School in 1977 and first reported in 1986.1 Unicompartmental, bicompartmental, and tricompartmental disease were managed with a variety of primary and revision components that allowed retention of both cruciates, the posterior cruciate ligament (PCL) only, or no cruciate ligaments. Additionally, the first metal-backed, rotating-bearing patella replacement was developed in 1977 to provide mobility with congruence in patellofemoral articulation. This New Jersey Low-Contact-Stress (LCS) total knee system (DePuy, Warsaw, Ind), initially used with cement in 1977, was expanded to noncemented use in 1981 with the availability of sintered-bead porous coating11 and remains the only knee system in the United States to have undergone formal Food and Drug Administration (FDA)Investigational Device Exemption (IDE) clinical trials in both cemented and cementless applications before being released for general clinical use12,13,14,15 (Fig. 10.3).