Total hip replacement in Germany has been performed in 227293 cases in 2015 and tendency is increasing. Although it is a standard intervention, freehand positioning of cup protheses has frequently poor accuracy. Image-based and image-free navigation systems improve the accuracy but most of them provide target positions as alphanumeric values on large-size screens beneath the patient site. In this case the surgeon always has to move his head frequently to change his eye-focus between incision and display to capture the target values. Already published studies using e.g. IPod-based displays or LED ring displays, show the chance for improvement by alternative approaches. Therefore, we propose a novel solution for an instrument-mounted small display in order to visualise intuitive instructions for instrument guidance directly in the viewing area of the surgeon.

For this purpose a solution consisting of a MicroView OLED display with integrated Arduino microcontroller, equipped with a Bluetooth interface as well as a battery has been developed. We have used an optical tracking system and our custom-designed navigation software to track surgical instruments equipped with reference bodies to acquire the input for the mini-display. The first implementation of the display is adapted to total hip replacement and focuses on assistance while reaming the acetabulum. In this case the reamer has to be centred to the middle point of the acetabular rim circle and its rotation axis must be aligned to the acetabular centre axis by Hakki. By means of these references the actual deviations between instrument and target pose are calculated and indicated. The display contains a cross-hair indicator for current position, two bubble level bars for angular deviation and a square in square indicator for depth control. All display parts are furnished with an adaptive variable scale. Highest possible resolution is 0.5 degrees angular, 1 millimeter for position and depth resolution is set to 2 mm.

Compared to existing approaches for instrument-mounted displays, the small display of our solution offers high flexibility to adjust the mounting position such that it is best visible for the surgeon while not constraining instrument handling. Despite the small size, the proposed visualisation symbols provide all information for instrument positioning in an intuitive way.

Deep periprostheses infection is a devastating complication that occurred in 8 to 20% of patients treated by en bloc resection and prosthetic reconstruction for bone sarcomas.

The systemic safety of high dose vancomycin loaded spacer has been investigated but rarely the elution of vancomycin in vivo. The aim of the study is to evaluate the elution of vancomycin into the site of the excision arthroplasty to see if effective bactericidal activity can be obtained.

Patients and Methods: From 2006 to 2008, 16 consecutive patients were managed by prosthetic exchange procedure using high dose vancomycin loaded cement. Patients were males :7, females :9. Average of age at the time of surgery was 22 years.

Antibiotic-loaded methylmethacrylate cement beads were prepared by adding 4 g of vancomycin powder to a 40 g pack of Palacos R cement in the operative place immediately before the operation. We used 4 G vancomycin per batch of 40 G cement and generally used 2 to 4 batches of cement in one spacer depending of the size and length of resection. The average dose of vancomycin was 7.5 G (4–14.5).

The wounds were closed with absorbable mono-filaments sutures over one suction drain.

Intravenous antibiotics excluding vancomycin were given for 6 to 24 weeks.

Patients biological values and the concentrations of vancomycin in the blood and in the aliquots of suction drainage were checked daily until removal of drain. Vancomycin was measured by fluorescent polarization immunoassay on the AxSYM analyzer (Abbott).

Results: the serum concentration of vancomycin remained in all patients under 2 μg/ml confirming the systemic safety of the method. Local concentration of vancomycin depended of the dose of vancomycin used and decreased quickly during the first week: half life :2.25 days. For a dose of 10 G vancomycin, the average concentration in the liquid from the drain was :

d1 :725μg/ml

on day 10, its remained over 35μg/ml vancomycin in the aliquot of the drain

These results should be compared to the bactericidal concentration of vancomycin for staphylococcus aureus:10 to 20 μg/ml for usual organisms, 20 to 40 for resistant organisms.

We had no reported cases of allergy, toxicity or intolerance.

Conclusion : high dose vancomycin spacers result in very low serum concentration without risk of systemic toxicity. In the operative wound, very high concentration are obtained, 10 to 20 fold bactericidal concentration for staphylococcus aureus.

Additional studies are needed, with longer follow-up to evaluate the clinical efficacy of this method.

Introduction: We carried out a revision of Necrotizing Fasciitis diagnosed in our Hospital from January 2000 to July 2008. Necrotizing Fasciitis is an infection of soft tissues, caused in most of cases by Streptococcus pyogenes. It is a dangerous infection, because it progresses quickly, and it can lead to death due to systemic toxicity.

Materials and Methods: The study includes 18 patients afected by Necrotizing fasciitis treated in our Hospital from January 2000 until July 2008. In order to identify risk factors and clinical emergency signs, clinical detailed information was obtained for each patient.

Results: In 70% of the cases, Streptococcus pyogenes was found as the main germ involved in Necrotizing Fasciitis. In inicial stages, the patients complained of pain, heat, swelling, reddening and crepitation of the affected subcutaneous tissues. In advanced stages, patients went in a state of neurogenic shock. Specific antibiotical therapy was necessary in all cases. Surgical treatment was performed in 80 % of the cases, consisting of fascial aperture and debridement of devitalized tissues. In spite of the intensive medical and surgical treatments, 10% of the cases died.

Conclusion: We consider the suspicion and knowledge of Necrotizing fasciitis is crucial in order to diagnose early and properly this infection disease. Then we can be able to establish a precocious and suitable treatment which can avoid the potentially fatal outcome.