Influence of the remelting process on the fatigue behavior of electron beam irradiated UHMWPE.

8 pages, 5 tables, 5 figures.Electron beam irradiation at doses below 150 kGy is a widely used technique to obtain highly crosslinked ultra-high-molecular-weight polyethylene (UHMWPE). Its current use in total joint replacement components may improve wear resistance and decrease UHMWPE particle debris. However, currently used post-irradiation thermal treatments, which aim to decrease the free radicals within the material, introduce microstructural changes that affect UHMWPE mechanical properties, particularly the fatigue strength. This influence may be crucial in total knee replacements, where fatigue-related damage limits the lifespan of the prosthesis. Therefore, more studies are required to understand UHMWPE fatigue after current crosslinking protocols. This study was planned to evaluate the influence of UHMWPE remelting after irradiation on the material fatigue resistance. The remelting was achieved at 150°C for 2 h on UHMWPE previously irradiated at 50, 100, and 150 kGy. Fatigue evaluation included short-term tests under cyclic tensile stress with zero load ratio, R = 0, and 1 Hz. In addition, stress-life testing was performed using 12% yield as the criterion for failure. Near-threshold fatigue crack propagation experiments were also performed at a frequency of 5 Hz, and crack length was measured in nonthermally treated and remelted irradiated UHMWPE. Crystallinity percentage was calculated from DSC measurements. The results pointed out that irradiation positively contributed to total life analysis, but the further remelting process decreased the flaw initiation resistance. On the other hand, both processes negatively affected the fatigue resistance of notched components. From a clinical point of view, the results suggest that the material fatigue behavior should be carefully studied in new UHMWPE to avoid changes related to material processing. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006Peer reviewe

Comparison of fibrin sealant and staples for attaching split-thickness autologous sheet grafts in patients with deep partial- or full-thickness burn wounds: a phase 1/2 clinical study.

We undertook a multicenter, randomized, controlled, phase 1/2 clinical study to investigate the safety and efficacy of a fibrin sealant containing 4 IU/ml thrombin (FS 4IU) for the attachment of autologous sheet grafts in patients with deep partial-thickness or full-thickness burn wounds. Fibrin sealant (FS 4IU) was compared with staples for adherence of sheet grafts in 40 patients. Patients had to have burn wounds measuring 40% TBSA or less with two comparable test sites measuring between 1% and 4% TBSA each. Wound beds were prepared before treatment assignment, which was randomized. Percent area of hematoma/seroma at Day 1 (P = .0138) and questionable viability at Day 5 (P = .0182) were significantly less for FS 4IU-treated sites. Median percent area of graft survival on Day 14 was 100% for both treatments (P = .3525). The percentage of completely closed sites generally was greater for FS 4IU-sites on Days 5 to 91; the maximum difference occurred at Day 28 (79.5% vs 59%; P = .0215). The safety profile of FS 4IU was excellent as indicated by the lack of any related serious adverse experiences. These findings indicate that FS 4IU is safe and effective for fixation of skin grafts, with outcomes similar to or better than staple fixation. The data suggest that FS 4IU is a promising candidate for further clinical studies focusing on skin graft adhesion and burn wound healing