Browsing by Author "Simon C. Roe, Committee Member"

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • No Thumbnail Available
    The Effectiveness of Cerclage Wiring on Stabilizing Intra-Operative Femoral Fractures During Cementless Total Hip Arthroplasty in Canines.
    (2008-05-14) McCulloch, Ryan Sterling; Ola L.A. Harrysson, Committee Member; Simon C. Roe, Committee Member; Peter L. Mente, Committee Chair
    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.
  • No Thumbnail Available
    Quantification of Chondrocyte Death and Proteoglycan Content in Mechanically Impacted Articular Cartilage
    (2004-06-17) Lossing, Jennifer Aimee; Peter L. Mente, Committee Chair; Simon C. Roe, Committee Member; Gary A. Mirka, Committee Member; C. Frank Abrams, Jr., Committee Member
    Impact injuries can lead to cellular and matrix changes in articular cartilage, similar to those occurring in the pathenogenesis of secondary osteoarthritis. The purpose of this study was to examine the changes in cartilage following an impact injury as a model for early osteoarthritic degradation. Using an in vitro organ culture model, the proteoglycan content and the viability of chondrocytes relative to the magnitude of an impact injury, the time following the injury and the relative location within the cartilage layer was examined. In this study, it was hypothesized that injurious mechanical loading would result in increased chondrocyte death and decreased proteoglycan content with increasing load and time in culture. Paired porcine knee joints were obtained fresh and patellae were removed using sterile techniques. A total of 36 patellae were used. Twelve patellar cartilage specimens were subjected to controlled mechanical injuries to a force level of 1000 N (medium) and 12 specimens at a force level of 2000 N (high). Twelve patellae were used as non-injured controls. Following impaction, the intact patellae were placed in organ culture for 0, 3, 7 or 14 days and subsequent degenerative changes over time were assessed. Cell viability was quantified using a MTT (3,(4,5-dimethylthiazoyl-2-yl) 2,5(diphenyl-tetrazolium bromide) assay and the percentage of dead cells at various positions was determined. Proteoglycan concentration was measured using Safranin-O staining intensities. There was a significant, location dependent, cell death increase with increasing impact load. A significant location dependent decrease in proteoglycan content was observed from medium impactions, while an increase in proteoglycan content was seen from high impactions. In conclusion, the magnitude of an impact load can significantly affect the degree of matrix changes throughout the depth of articular cartilage tissue over time.