title: Improving peri-prosthetic bone adaptation around cementless hip stems: a clinical and finite element study.
abstract: This study assessed whether the Symax™ implant, a modification of the Omnifit(®) stem (in terms of shape, proximal coating and distal surface treatment), would yield improved bone remodelling in a clinical DEXA study, and if these results could be predicted in a finite element (FE) simulation study. In a randomized clinical trial, 2 year DEXA measurements between the uncemented Symax™ and Omnifit(®) stem (both n=25) showed bone mineral density (BMD) loss in Gruen zone 7 of 14% and 20%, respectively (p<0.05). In contrast, the FE models predicted a 28% (Symax™) and 26% (Omnifit(®)) bone loss. When the distal treatment to the Symax™ was not modelled in the simulation, bone loss of 35% was predicted, suggesting the benefit of this surface treatment for proximal bone maintenance. The theoretical concept for enhanced proximal bone loading by the Symax™, and the predicted remodelling pattern were confirmed by DEXA-results, but there was no quantitative match between clinical and FE findings. This was due to a simulation based on incomplete assumptions concerning the yet unknown biological and mechanical effects of the new coating and surface treatment. Study listed under ClinicalTrials.gov with number NCT01695213.
authors.affiliation: Department of Orthopaedic Surgery, Caphri Research Institute, Maastricht University Medical Centre, 6202 AZ Maastricht, The Netherlands. Electronic address: r.ten.broeke@mumc.nl.
authors.forename: René H M
authors.initials: RH
authors.lastname: ten Broeke
authors.affiliation: Orthopaedic Research Laboratory, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands.
authors.forename: Maria
authors.initials: M
authors.lastname: Tarala
authors.affiliation: Department of Orthopaedic Surgery, Caphri Research Institute, Maastricht University Medical Centre, 6202 AZ Maastricht, The Netherlands.
authors.forename: Jacobus J
authors.initials: JJ
authors.lastname: Arts
authors.affiliation: Orthopaedic Research Laboratory, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands.
authors.forename: Dennis W
authors.initials: DW
authors.lastname: Janssen
authors.affiliation: Orthopaedic Research Laboratory, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands; Laboratory for Biomechanical Engineering, University of Twente, 7522 NB Enschede, The Netherlands.
authors.forename: Nico
authors.initials: N
authors.lastname: Verdonschot
authors.affiliation: Department of Orthopaedic Surgery, Caphri Research Institute, Maastricht University Medical Centre, 6202 AZ Maastricht, The Netherlands.
authors.forename: Rudolph G T
authors.initials: RG
authors.lastname: Geesink
mesh_terms: D015502:Absorptiometry, Photon; D000222:Adaptation, Physiological; D000328:Adult; D000368:Aged; D016723:Bone Remodeling; D005260:Female; D020342:Finite Element Analysis; D006621:Hip Joint / Q000502:physiology*; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged
keywords: Bone mineral density; Cementless hip arthroplasty; DEXA; Finite element analysis