The wear of fixed and mobile bearing unicompartmental knee replacements

Abstract

Unicompartmental knee replacements (UKR) are an option for surgical intervention for the treatment of single-compartment osteoarthritis. The aim of this study was to compare the wear of a low-conformity fixed-bearing UKR with a conforming mobile bearing UKR under two kinematic conditions, to investigate the effect of implant design and kinematics on wear performance in a physiological knee wear simulator. Under both sets of kinematic conditions, the relatively low-conforming fixed UKR showed lower wear, compared with the more conforming anterior-posterior sliding mobile bearing. However, it should be noted that differences in materials between the two designs also contribute to the relative wear performance of the bearings. The combined wear of the medial and lateral bearings of the fixed-bearing UKR as a 'total knee' were significantly reduced compared with a fixed-bearing total knee replacement studied under the same kinematic conditions.

Increase of tibial slope reduces backside wear in medial mobile bearing unicompartmental knee arthroplasty

“…The wear rate of 3.5 mg/million cycles in the 0°slope group is slightly less compared to the current literature. In a wear analysis of the Oxford UKA, the wear rate was 5.72 mg/million cycles and in an older study with a different polyethylene it was 9.7 mg/million cycles (Brockett et al, 2011;Scott and Schroeder, 2000). Kretzer also analysed the Univation prosthesis and found a higher wear rate of 10.7 mg/million cycles (Kretzer et al, 2011).…”

Comparison of CMM and Micro-CT Volumetric Analysis of Polyethylene Tibial Knee Inserts in Total Knee Replacement

“…and allowed to stabilize for a period of 48 hours. The change in mass was assessed using the AT 201 balance (Mettler Toledo Inc., Columbus, Ohio, USA), and the volumetric loss was calculated using the following equation, taking the density of polyethylene as 0.931 g/mm 3 [12]. The samples were measured using CMM (Legex 322, Mitutoyo, UK) with known wear volume determined using gravimetric analysis.…”

Revision nach unikondylärer Knieprothese

“…In-vitroAbriebmessungen haben diesen Effekt nachgewiesen [4,26]. Allerdings zeigen hervorragende Langzeitergebnisse über mittlerweile 20 Jahre, dass dieser Effekt in vivo wenig bedeutsam zu sein scheint, solange das Inlay frei und ungehindert, ohne Impingement, gleiten kann [30,34].…”