The effect on wear of lift‐off in total knee arthroplasty

Article type: Research Article

Authors: Todo, Shinichi^; | Blunn, Gordon W. | Harrison, Mark | Freeman, Michael A.R.

Affiliations: Yasaka‐cho Kokuho Hospital, Kyoto, Japan | Centre for Biomedical Engineering, Insititute of Orthopaedics and Musculo‐Skeletal Science, University College London, Stanmore, Middlesex, UK | The Bone and Joint Research Unit, The Royal London Hospital, London, UK

Note: [] Correspondence to: Shinichi Todo, Yasaka‐cho Kokuho Hospital, 3452‐1 Mizotani Yasaka‐cho Takeno‐gun, Kyoto 627‐0111, Japan. Tel.: +81 772 65 2003; Fax: +81 772 65 4136; E‐mail: todos@fb3.so‐net.ne.jp.

Abstract: Femoral lift‐off has been reported in total knee arthroplasty using dynamic fluoroscopic analysis. However, the effect of femoral lift‐off on ultra‐high‐molecular‐weight polyethylene (UHMWPE) is not clear. The objective of this study was to evaluate the effect of lift‐off movement on the wear of UHMWPE using a pin‐on‐disc testing machine. Using oxidised UHMWPE, delamination was observed in 70% of the discs with lift‐off movement, as against none in without lift‐off movement (p=0.0603). In non‐oxidised UHMWPE the depth of the wear track was increased in the impact area after lift‐off, but there was no delamination and no increase in wear as measured by weight loss. UHMWPE can sustain the impact of after lift‐off with neither delamination nor wear by other mechanisms. In contrast, degraded (i.e., oxidised) UHMWPE undergoes delamination after lift‐off. Since it is probable that lift‐off cannot be prevented, oxidised UHMWPE should never be used in TKA.

Keywords: Total knee arthroplasty, UHMWPE, lift‐off, delamination, wear

Journal: Bio-Medical Materials and Engineering, vol. 13, no. 3, pp. 231-234, 2003