A Novel Technique to Aid Insertion of the Mobile Meniscal Bearing of the Oxford Unicompartmental Knee Arthroplasty

Abstract

The Oxford unicompartmental knee arthroplasty (Biomet Ltd, Bridgend, UK) has a spherical femoral component, flat tibial component, and a mobile congruent polyethylene meniscal bearing. The bearing is designed to reduce polyethylene wear while allowing unrestrained tibio-femoral movement.1 Because of the elevated anterior and posterior lips of the bearing, required to give congruency, it can be difficult to insert the definitive bearing and on occasions, cause the bearing to be dropped. The authors propose a novel technique for the insertion of the mobile meniscal bearing of the Oxford unicompartmental knee arthroplasty. Once the appropriate size and thickness of the meniscal bearing has been selected and both the femoral and tibial components are implanted, the knee is flexed over the thigh support. The mobile bearing is positioned upon the congruent surface of the femoral prosthesis against the vertical anterior bone cut and supported in place by the surgeon’s thumb (Fig. 1A). The surgeon subsequently extends the replaced knee and the bearing is prevented from sliding by the vertical anterior bone cut (Fig. 1B). This allows the bearing to snap into place as the knee reaches full extension (Fig. 1C).FIGURE 1: Steps for insertion of mobile meniscal bearing. A, Step 1. B, Step 2. C, Step 3.In our experience, this technique provides a reliable and reproducible method for the insertion of the mobile meniscal bearing component of the Oxford unicompartmental knee arthroplasty. This technique has been used by the senior author for 8 years with no complications or dropped bearings.