Mechanical and microbiological testing concept for activatable anti-infective biopolymer implant coatings.

An anti-infective bilayer implant coating with selectively activatable properties was developed to prevent biofilm formation and to support the treatment of periprosthetic infection as a local adjunct to current treatment concepts. In a first step, Ti6Al4V discs were coated with a permanent layer of Poly(l-lactide) (PLLA) including silver ions. The PLLA could be optionally released by the application of extracorporeal shock waves. In a second step, a resorbable layer of triglyceride (TAG) with incorporated antibiotics was applied. The second layer is designed for resorption within weeks. Prior to approval and clinical application, a comprehensive evaluation process to determine mechanical/physical and microbiological properties is obligate. To date, none of the existing test standards covers both drug-releasing and activatable coatings for orthopedic implants. Therefore, a comprehensive test concept was developed to characterize the new coating in a pilot series. The coatings were homogeneously applied on the Ti6Al4V substrate, resulting in an adhesion strength sufficient for non-articulating surfaces for PLLA. Proof of the extracorporeal shockwave activation of PLLA was demonstrated both mechanically and microbiologically, with a simultaneous increase of biocompatibility compared to standard electroplated silver coating. Wettability was significantly reduced for both layers in comparison to the Ti6Al4V substrate. Thus, potentially inhibiting biofilm formation. Furthermore, the TAG coating promoted cell proliferation and bacterial eradication. In conclusion, the testing concept is applicable for similar biopolymer coating systems. Furthermore, the extracorporeal activation could represent a completely new supportive approach for the treatment of periprosthetic joint infections.

High-energy extracorporeal shock wave therapy for nontraumatic osteonecrosis of the femoral head.

BACKGROUND: Nontraumatic osteonecrosis of the femoral head (ONFH) is treated with a series of methods. High-energy extracorporeal shock wave therapy (ESWT) is an option with promising mid-term outcomes. The objective of this study was to determine the long-term outcomes of ESWT for ONFH. METHODS: Fifty-three hips in 39 consecutive patients were treated with ESWT in our hospital between January 2005 and July 2006. Forty-four hips in 31 patients with stage I-III nontraumatic ONFH, according to the Association Research Circulation Osseous (ARCO) system, were reviewed in the current retrospective study. The visual analog pain scale (VAS), Harris hip score, radiography, and magnetic resonance imaging were used to estimate treatment results. The progression of ONFH was evaluated by imaging examination and clinical outcomes. The results were classified as clinical success (no progression of hip symptoms) and imaging success (no progression of stage or substage on radiography and MRI). RESULTS: The mean follow-up duration was 130.6 months (range, 121 to 138 months). The mean VAS decreased from 3.8 before ESWT to 2.2 points at the 10-year follow-up (p < 0.001). The mean Harris hip score improved from 77.4 before ESWT to 86.9 points at the 10-year follow-up. The clinical success rates were 87.5% in ARCO stage I patients, 71.4% in ARCO stage II patients, and 75.0% in ARCO stage III patients. Imaging success was observed in all stage I hips, 64.3% of stage II hips, and 12.5% of stage III hips. Seventeen hips showed progression of the ARCO stage/substage on imaging examination. Eight hips showed femoral head collapse at the 10-year follow-up. Four hips in ARCO stage III and one hip in ARCO stage II were treated with total hip arthroplasty during the follow-up. Three were performed 1 year after ESWT, one at 2 years, and one at 5 years. CONCLUSIONS: The results of the current study indicated that ESWT is an effective treatment method for nontraumatic ONFH, resulting in pain relief and function restoration, especially for patients with ARCO stage I-II ONFH.

High-energy extracorporeal shock waves in treatment of nonunion and delayed union:preliminary results / 中华创伤骨科杂志

Objective To observe the effects of the Ossatron high-energy shock waves on bone nonunion and delayed union.Methods Between October 2004 and October 2005,18 patients with nonunion and four patients with delayed union were treated with high-energy extracorporeal shock wave therapy(Ossatron,HMT Co., Swiss).Facture lines were located with C-arm X-ray before treatment.Parameters of shock waves were decided according to fracture sites.Patients with unstable fixation received plaster or bracing for 6 to 8 weeks after treatment. After therapy,follow-up radiography was performed at 6 and 12 weeks and monthly afterwards until the fracture united. Results The mean follow-up was 6.7 months(range,3 to 12 months).There were no complications except local petechial hemorrhage and local swelling in 10 patients.Thirteen patients(59.1%)got bony union,including 12 patients(66.7% )with stable internal fixation,and the average healing time was 4.3 months(range,6 weeks to 6 months).Nine fractures(40.9%)still suffered nonunion.Conclusion High-energy shock waves are a good alternative therapy for nonunion and delayed union,with obvious advantages of being non-invasive and safe.