Correa TA, Pal B, van Arkel RJ, Vanacore F, Amis AA. Reduced tibial strain-shielding with extraosseous total knee arthroplasty revision system.
Med Eng Phys 2018;
62:22-28. [PMID:
30314902 PMCID:
PMC6236098 DOI:
10.1016/j.medengphy.2018.09.006]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 09/07/2018] [Accepted: 09/30/2018] [Indexed: 11/16/2022]
Abstract
A novel extracortical support system for revision of failed knee prostheses.
Shown to reduce metaphyseal stress-shielding versus intramedullary stem fixation.
Reduces bone loss and enables bone grafting of defects after implant loosening.
Enables use of conventional prosthesis in a revision scenario.
Background
Revision total knee arthroplasty (RTKA) has poorer results than primary total knee arthroplasty (TKA), and the prostheses are invasive and cause strain-shielding of the bones near the knee. This paper describes an RTKA system with extracortical fixation. It was hypothesised that this would reduce strain-shielding compared with intramedullary fixation.
Methods
Twelve replica tibiae were prepared for full-field optical surface strain analysis. They were either left intact, implanted with RTKA components with cemented intramedullary fixation stems, or implanted with a novel design with a tibial tray subframe supported by two extracortical fixation plates and screw fixation. They were loaded to simulate peak walking and stair climbing loads and the surface strains were measured using digital image correlation. The measurements were validated with strain gauge rosettes.
Results
Compared to the intact bone model, extracortical fixation reduced surface strain-shielding by half versus intramedullary fixation. For all load cases and bone regions examined, the extracortical implant shielded 8–27% of bone strain, whereas the intramedullary component shielded 37–56%.
Conclusions
The new fixation design, which offers less bone destruction than conventional RTKA, also reduced strain-shielding. Clinically, this design may allow greater rebuilding of bone loss, and should increase long-term fixation.
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