INTRODUCTION Ultra-high molecular weight polyethylene (UHMWPE) is used for medical device applications such as joint replacement, artificial ligaments, and maxillofacial reconstruction . Polyethylene has a low X-ray absorbance, which prevents surgeons using techniques such as fluoroscopy guided surgery to aid implant positioning, or radiography to follow-up implant position and function . This study investigates the diffusion of iodised oil into UHMWPE to increase the radio-opacity of the biomaterial. Diffusion is a method which has been used to introduce α‑tocopherol into polyethylene for anti-oxidant purposes . Iodised oil is used clinically as a contrast agent and is lipophilic like α‑tocopherol. The hypothesis of this study was that iodised oil would diffuse into UHMWPE in a similar manner to α‑tocopherol, and increase its radio-opacity. EXPERIMENTAL METHODS UHMWPE sheet of 5 mm thickness (PE-1000, DirectPlastics, UK) was machined into samples of dimensions of 10 mm x 10 mm x 5 mm. Gravimetric measurements and dimensional data were measured. Samples (n=3) were immersed in the iodised oil (Lipiodol, Guerbert, France) and held for 24 hours at 100˚C, 110˚C, 120˚C, and 130˚C. Control samples were not immersed but were subjected to the same temperature conditions. All samples were then cleaned ultrasonically in water and dried with a cotton gauze. Gravimetric and dimensional data was re-measured. A CT scanner (XT H 225 ST, Nikon, UK) was used to image the samples. Cross-sectional intensity profiles of the samples were used to determine the diffusion coefficients. Compressive load of 3 kN was applied to the samples using an electromechanical test machine (5965, Instron, UK). RESULTS AND DISCUSSION Treated samples were visibly darker and increased in mass and volume after treatment. The CT intensity of samples increased after treatment. The calculated diffusion coefficients from the profiles were 88.7 ± 12.5 mm/s x 106 at 100˚C, 81.6 ± 12.5 mm/s x 106 at 110˚C, 515.6 ± 14.1 mm/s x 106 at 120˚C, and 360.5 ± 18.9 mm/s x 106 at 130˚C. These values are slightly higher than those reported for α‑tocopherol3, though are of a similar magnitude. CONCLUSION Diffusion of the iodised oil into the polyethylene samples increased the radiopacity, and the calculated diffusion constant was comparable to reported values for vitamin E polyethylene. However the iodised oil reduced the compressive modulus of the material, further work will examine the influence of cross-linking. REFERENCES 1. Maitz MF, Biosurf & Biotrib 1:161-176, 2015. 2. Kozakiewicz M, et al., Clin Oral Invest: 1-7, 2016. 3. Oral E, et al., Biomaterials 28:5225-5237, 2007. ACKNOWLEDGMENTS The authors would like to thank Nick Waywell for his assistance with the mechanical testing.
|Publication status||Published - 7 Sep 2017|
|Event||European Society for Biomaterials 2017 - Megaron Athens International Conference Centre, Athens, Greece|
Duration: 4 Sep 2017 → 8 Sep 2017
Conference number: 28
|Conference||European Society for Biomaterials 2017|
|Period||4/09/17 → 8/09/17|