The mobile bearing, low contact stress, total knee replacement arthroplasty has proven successful with a high long-term survival rate and a low complication rate. Over 1,200 LCS knee has been successful with 97% survival.

However, we found fifteen knees showing early failure of mobile meniscal bearings with fracture, dislocation, and early wear, in some cases within three years. This caused the knee to subluxate and the bearings to dislocate. All fifteen knees had good surgical results with high HSS scores, normal valgus alignment, adequate sizing of the implants, lack of changes in the prosthese/bone interface as evidenced by the x-rays, and good ligament balancing.

The reasons of the failure were: 1. Proportionately overweight patients. 2. Probable poor polyethylene quality due to air gamma radiation sterilization of the implant. 3. Overuse by the patients, causing undue load on the polyethylene. All patients with meniscal bearing failure had undergone revision surgery with good surgical results.

We feel this merits further study to determine the relationship between the load and size of polyethylene mass in the rate of wear. While there are studies in the importance of thickness in relation to wear, we found no study on the effect that load has on the mass of polyethylene. We recommend a larger polyethylene tibial implant and rotating platform prostheses be used for an overweight patient and/or patient with high level of activity, both of which forecast a high load on the implant.