All-Polyethylene Tibial Components for Unicompartmental Knee Arthroplasty

All-polyethylene and metal-backed tibial components are available for unicompartmental knee arthroplasty. Although the early design of all-polyethylene component was largely replaced by metal-backed components, improvements in polyethylene wear characteristics, component design, and surgical technique have renewed interest in all-polyethylene (InLay) components. In comparison with metal-backed (OnLay) designs, InLays require less bone resection and are easier to revise total knee replacements. Early aseptic loosening, tibial component subsidence, and anterior knee pain were found to be the primary contributors to failure of InLay designs. Controversy remains whether InLay or OnLay components are preferable for unicompartmental knee arthroplasty. Despite the component design, proper component alignment, cementation technique, and ligamentous balance remain crucial for implant survival and are highlighted in this article along with a comparison of InLay and OnLay results.