Optimal interference of the tibial component of the cementless Oxford Unicompartmental Knee Replacement

Bone & Joint Research

article

S. Campi¹  S. J. Mellon¹  D. Ridley¹  B. Foulke¹  C. A. F. Dodd¹  H. G. Pandit¹  D. W. Murray¹ 

[1] University of Oxford

关键词: Interference fit;    Cementless implants;    Push-in force;    Pull-out force;   

DOI  :  10.1302/2046-3758.73.BJR-2017-0193.R1

学科分类：骨科学

来源: British Editorial Society Of Bone And Joint Surgery

【 摘 要 】

Objectives The primary stability of the cementless Oxford Unicompartmental Knee Replacement (OUKR)relies on interference fit (or press fit). Insufficient interference may cause implant loosening,whilst excessive interference could cause bone damage and fracture.The aim of this study was to identify the optimal interference fit by measuring the forcerequired to seat the tibial component of the cementless OUKR (push-in force) and the forcerequired to remove the component (pull-out force).Materials and MethodsSix cementless OUKR tibial components were implanted in 12 new slots prepared on blocksof solid polyurethane foam (20 pounds per cubic foot (PCF), Sawbones, Malmo, Sweden)with a range of interference of 0.1 mm to 1.9 mm using a Dartec materials testing machineHC10 (Zwick Ltd, Herefordshire, United Kingdom) . The experiment was repeated with cellular polyurethane foam (15 PCF), which is a more porous analogue for trabecular bone.ResultsThe push-in force progressively increased with increasing interference. The pull-out forcewas related in a non-linear fashion to interference, decreasing with higher interference.Compared with the current nominal interference, a lower interference would reducethe push-in forces by up to 45% (p < 0.001 One way ANOVA) ensuring comparable (orimproved) pull-out forces (p > 0.05 Bonferroni post hoc test). With the more porous boneanalogue, although the forces were lower, the relationship between interference and pushin and pull-out force were similar.ConclusionsThis study suggests that decreasing the interference fit of the tibial component of thecementless OUKR reduces the push-in force and can increase the pull-out force. An optimalinterference fit may both improve primary fixation and decrease the risk of fracture.

【 授权许可】

CC BY-NC