Force is required to prepare the bone and achieve the initial press fit for an uncemented hip implant during Total Hip Arthroplasty (THA) surgery. In some situations, this force may cause of an intra-operative femoral fracture resulting in an unstable implant, subsidence, and pain for the patient. Many of the less extensive fractures can be repaired with cerclage wire or cables. This study aimed to evaluate the ability of double loop cerclage wire(s) to restore the stability of the implant-bone interface after a simulated intra-operative fracture. Nine femora from euthanized canine were harvested for in vitro testing. The femora were prepared for implantation of an uncemented femoral stem (BFX⢠series, BioMedtrix, Boonton, NJ). They were then potted and mounted in a materials testing machine (MTS 858 Mini Bionix II, Eden Prairie, MN). The implant was driven to a clinically appropriate height, struck with 3 impacts (simulating seating hammer blows), and then the stem loaded to failure. Once a fracture occurred, the implant was extracted, the femur was repaired with appropriate cerclage, re-broached, and re-implanted. The repaired specimen was then tested in the same fashion as the intact bone. During loading, the displacement of the implant relative to the bone was measured using a linearly variable differential transformer LVDT. The force to initiate subsidence, the peak force at failure, and the peak subsidence distance were compared between intact (pre-fracture) and repaired (post-fracture) specimens using ANOVA with blocking by specimen. The wired specimens demonstrated a higher force to initiate subsidence than the intact specimens (2378.8N ± 656.9N c.f. 1705.1N ± 584.5N; p= 0.0019). The wired specimens also sustained a higher peak force at failure than the intact specimens (3309.0N ± 609.14N c.f. 2276.3N ± 855.6N; p=0.0022). Furthermore, the wired specimens did not subside a significantly greater amount than the intact specimens (Intact: 3.90mm, SD=2.09mm; Wired: 6.71mm, SD=3.66mm; p-value = 0.0600). Cerclage wiring of intra-operative femoral fractures was able to restore the integrity of the femur and enable a stable implant-bone interface to be achieved.
| Identifer | oai:union.ndltd.org:NCSU/oai:NCSU:etd-05132008-095547 |
| Date | 14 May 2008 |
| Creators | McCulloch, Ryan McCulloch Sterling |
| Contributors | Ola L.A. Harrysson, Simon C. Roe, Peter L. Mente |
| Publisher | NCSU |
| Source Sets | North Carolina State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://www.lib.ncsu.edu/theses/available/etd-05132008-095547/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dis sertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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