While high-performance ceramics like alumina and zirconia exhibit excellent wear resistance, they provide poor osseointegration capacity. As osseointegration is crucial for non-cemented joint prostheses, new techniques have been successfully developed for biofunctionalizing high-performance ceramic surfaces. Stable cell adhesion can be achieved by covalently bound specific peptides. In this study we investigate the effect of sterilization processes on organo-chemically functionalized surfaces.

To enhance the performance of alumina-toughened zirconia ceramics (ATZ), a 3-aminopropyldiisopropylethoxysilane (APDS) monolayer was applied and coupled with cyclo-RGD peptides (cRGD) by using bifunctional crosslinker bis(sulfosuccinimidyl)suberat (BS³). The samples were sterilized using e-beam or gamma-sterilization at 25 kGy, either before or after biofunctionalization with cRGD. Functionalization stability was investigated by contact angle measurements. The functionality of cRGD after sterilization was demonstrated using proliferation tests and cytotoxicity assays. Immunofluorescence staining (pFAK, Actin, DAPI) was conducted to evaluate the adhesion potential between the samples and human mesenchymal stem cells (hMSCs).

Functionalized samples before and after sterilization showed no significant difference regarding their contact angles. A proliferation test demonstrated that the cells on functionalized samples proliferate significantly more than on untreated samples before and after sterilization. hMSCs showed a significant higher proliferation on gamma sterilized samples compared to all other groups after 14 days. It was confirmed that the samples did not exhibit cytotoxic behavior before or after sterilization. Fluorescence microscopy demonstrated that both, cells on sterilized and on non-sterilized samples, expressed high levels of pFAK-Y397.

The investigated functionalization enables improved adhesion and proliferation of hMSCs and is stable against the investigated sterilization processes. This is of importance as the option of having a sterile product enables the start of the translation of this biofunctional coating towards preclinical and subsequently first-in-man applications.

Acknowledgments: We acknowledge the financial support of the Federal Ministry of Education and Research, BMBF (13GW0452A-C).

Background

Large bone defects still challenge the orthopaedic surgeon. Local vascularity at the site of the fracture has an important influence on the healing procedure. Vascular endothelial growth factor (VEGF) and it's receptor (VEGFR2) are potent inducer of angiogenesis during the fracture healing. Aim of the present study was the investigation of critical size fracture (CSF) healing in VEGFR2-luc mice using tailored scaffolds.

Aims: Comparison of the effectiveness of the injection of hyaluronic acid (Ostenil¨) and cortisone (Volon¨) into the facet joints in the treatment of facet joint syndrome. Methods: 60 patients suffering from low back pain due to degenerative arthritis of the facet joints were included in this randomized, controlled, double-blinded, clinical trial. 30 patients received intra-articular injections of hyaluronic acid (Ostenil¨) and 30 patients received intra-articular injections of 10mg triamcinolon-hexacetonid (Volon 10¨). The facet joints of the spinal segments L3/L4, L4/L5, and L5/S1 were injected bilaterally with computed tomography guidance in intervals of one week each. Clinical evaluation was carried out one week prior þrst injection, at the day of þrst injection, after one, two, and three weeks, and after three and six months. Clinical assessment was carried out using the visual analog scale for pain, the Roland Morris Questionnaire, and the Oswestry Disability Questionnaire. Quality of life was assessed using the SF-36 health questionnaire. Radiological assessment was done according to Kellgren. Results: Pain reduction was achieved faster in the Volon 10¨group. After three months the Ostenil¨group reached better pain reduction and this effect lasted for a longer period. The Roland Morris score, the Oswestry Disability Questionaire, as well as the Low Back Pain Outcome Score showed signiþcantly better results in the Ostenil¨group after 3 and 6 months follow-up. Conclusion: Even though no signiþcant difference was found in the short-term follow-up, the results in the Ostenil¨group were comparable to the Volon 10¨group, and were signiþcantly better in the long-term follow up. Thus the intra-articular injection of hyal-uronic acid (Ostenil¨) is an effective alternative in the treatment of low back pain caused by facet joint syndrome, avoiding the known side effects of cortisone.