Splint sterilization--a potential registration hazard in computer-assisted surgery.

PURPOSE: Registration of preoperative targeting information for the intraoperative situation is a crucial step in computer-assisted surgical interventions. Point-to-point registration using acrylic splints is among the most frequently used procedures. There are, however, no generally accepted recommendations for sterilization of the splint. An appropriate method for the thermolabile splint would be hydrogen peroxide-based plasma sterilization. This study evaluated the potential deformation of the splint undergoing such sterilization. Deformation was quantified using image-processing methods applied to computed tomographic (CT) volumes before and after sterilization. MATERIALS AND METHODS: An acrylic navigation splint was used as the study object. Eight metallic markers placed in the splint were used for registration. Six steel spheres in the mouthpiece were used as targets. Two CT volumes of the splint were acquired before and after 5 sterilization cycles using a hydrogen peroxide sterilizer. Point-to-point registration was applied, and fiducial and target registration errors were computed. Surfaces were extracted from CT scans and Hausdorff distances were derived. Effectiveness of sterilization was determined using Geobacillus stearothermophilus. RESULTS: Fiducial-based registration of CT scans before and after sterilization resulted in a mean fiducial registration error of 0.74 mm; the target registration error in the mouthpiece was 0.15 mm. The Hausdorff distance, describing the maximal deformation of the splint, was 2.51 mm. Ninety percent of point-surface distances were shorter than 0.61 mm, and 95% were shorter than 0.73 mm. No bacterial growth was found after the sterilization process. CONCLUSION: Hydrogen peroxide-based low-temperature plasma sterilization does not deform the splint, which is the base for correct computer-navigated surgery.

Treatment and outcome of parosteal osteosarcoma: biological versus endoprosthetic reconstruction.

BACKGROUND AND OBJECTIVES: Due to its good prognosis despite local recurrence, more and less invasive methods for surgical treatment of parosteal osteosarcoma (POS) have been described. Aim of this retrospective single-center study was to investigate differences in outcome after biological and prosthetic reconstruction. METHODS: A total of 28 patients with POS, 14 females, 14 males, mean age of 27 years (median, 24 years; range 15-59 years), mean follow-up of 130 months (median, 104 months; range, 9-383 months), underwent wide tumor resection and prosthetic reconstruction (12 patients, 42.9%), less extensive resection and biological reconstruction (11 patients, 39.3%), rotationplasty (three patients, 10.7%), or amputation (two patients, 7.1%). RESULTS: There were two cases of local recurrence in patients with biological reconstruction and three cases of pulmonary metastases, leading to death of disease in two. Ten-year disease-specific survival was 91.1%. There was no significant difference between prosthetic and biological reconstruction in terms of local recurrence, metastasis, or functional outcome (mean MSTS Score, 85%). There were significantly more revisions in prosthetic reconstructions. CONCLUSIONS: Given that the resection of the tumor has clear margins, both prosthetic and biological reconstruction show similar results; prostheses allow better local tumor control, however, require more revisions over time.

Quantity of ethanol absorption after excessive hand disinfection using three commercially available hand rubs is minimal and below toxic levels for humans.

BACKGROUND: Despite the increasing promotion of alcohol-based hand rubs and the worldwide use of ethanol-based hand rubs in hospitals only few studies have specifically addressed the issue of ethanol absorption when repeatedly applied to human skin. The aim of this study was to assess if ethanol absorption occurs during hygienic and surgical hand disinfection using three different alcohol-based hand-rubs, and to quantify absorption levels in humans. METHODS: Twelve volunteers applied three hand-rubs containing 95% (hand-rub A), 85% (hand-rub B) and 55% ethanol (hand-rub C; all w/w). For hygienic hand disinfection, 4 mL were applied 20 times for 30 s, with 1 minute break between applications. For surgical hand disinfection, 20 mL of each hand rub was applied to hands and arms up to the level of the elbow 10 times for 3 minutes, with a break of 5 minutes between applications. Blood concentrations of ethanol and acetaldehyde were determined immediately prior and up to 90 minutes after application using head space gas chromatography. RESULTS: The median of absorbed ethanol after hygienic hand disinfection was 1365 mg (A), 630 mg (B), and 358 mg (C). The proportion of absorbed ethanol was 2.3% (A), 1.1% (B), and 0.9% (C). After surgical hand disinfection, the median of absorbed ethanol was 1067 mg (A), 1542 mg (B), and 477 mg (C). The proportion of absorbed ethanol was 0.7% (A), 1.1% (B), and 0.5% (C). The highest median acetaldehyde concentration after 20 hygienic hand disinfections was 0.57 mg/L (hand-rub C, after 30 min), after 10 surgical hand disinfections 3.99 mg/L (hand-rub A, after 20 minutes). CONCLUSION: The overall dermal and pulmonary absorption of ethanol was below toxic levels in humans and allows the conclusion that the use of the evaluated ethanol-based hand-rubs is safe.

Expression of the melatonin receptor (MT) 1 in benign and malignant human bone tumors.

The beneficial effects of melatonin on bone homeostasis have been shown in various diseases. As this indoleamine causes dose-dependent modulation of bone-forming osteoblast and bone-resorbing osteoclast activities by receptor-independent and -dependent pathways, we investigated the expression of G-protein-coupled melatonin receptors (MTs) in malignant and non-malignant human bone lesions. By TaqMan polymerase chain reaction (PCR), we analyzed 30 specimens from osteosarcoma and 11 from benign bone tumors for MT1-mRNA expression. Furthermore, we determined mRNA expression levels of the osteoclast activity-stimulating receptor activator of nuclear factor-kappa B ligand (RANKL) and its counterpart osteoprotegerin (OPG). Although mean MT1-mRNA levels were similar (P = 0.596) in malignant (4.39 +/- 4.98-fold) and benign samples (4.64 +/- 6.81-fold), the highest MT1-mRNA levels (up to 27-fold) were observed in individual osteosarcomas, particularly, in two specimens of patients with local recurrence of the tumor. Moreover, mean RANKL- and OPG-mRNA levels were similar in malignant and benign specimens (RANKL: 7.38 +/- 9.61-fold versus 3.57 +/- 3.11-fold, P = 0.207; OPG: 23.45 +/- 32.76 versus 8.07 +/- 7.23-fold, P = 0.133). Again, highest RANKL- and OPG-mRNA levels (up to 41- and 160-fold, respectively) were observed in individual osteosarcomas. Expression of MT1-mRNA was confirmed in two human osteosarcoma cell lines (HOS, MG63). High expression levels of MT1-mRNA together with low OPG-mRNA were found in both osteosarcoma cell lines, while in normal human osteoblasts and bone marrow stromal cells, high OPG-mRNA levels were associated with low MT1-mRNA levels. These data on the abundant expression of MT1-mRNA in human bone tumors and osteosarcoma cells lines suggest an important role for MT1 in bone pathology.

Metatarsal reconstruction with use of free vascularized osteomyocutaneous fibular grafts following resection of malignant tumors of the midfoot. A series of six cases.

BACKGROUND: Bone and soft-tissue sarcomas are uncommon, and their location in the foot is extremely rare. While limb salvage has become the standard of care in the treatment of sarcoma in an extremity, the unique anatomy of the foot presents challenges in reconstructing a viable and functional limb. METHODS: Between 1998 and 2005, we used free microvascularized osteomyocutaneous fibular grafts to reconstruct the defects created after extensive midfoot resection in six consecutive patients with a primary malignant tumor. In all but one patient, the extent of the resection involved at least two metatarsals. The mean age (and standard deviation) at the time of the operation was 30+/-13 years. At the final follow-up examination, clinical and radiographic evaluations were performed on all patients, and functional outcome and quality of life were assessed with use of the Musculoskeletal Tumor Society score, the American Orthopaedic Foot and Ankle Society Score, and the Toronto Extremity Salvage Score. RESULTS: The median duration of follow-up was 52.2 months. Limb salvage was achieved in five patients. In the remaining patient, amputation was necessary because of flap failure. Revision surgery was necessary in all patients because of complications (skin ulcerations in three patients; hematoma in two patients; and infection, necrosis of the second toe, and flap necrosis in one patient each). At the time of final follow-up, five patients had satisfactory function and reported good quality of life. The average Musculoskeletal Tumor Society, American Orthopaedic Foot and Ankle Society, and Toronto Extremity Salvage scores were 82%, 75 points, and 92%, respectively. At the time of the final follow-up, five patients had no evidence of disease and one patient had disease. CONCLUSIONS: Following the resection of a malignant tumor in the midfoot, the use of microvascularized osteomyocutaneous fibular grafts has proven to be a successful surgical technique, offering an alternative to ablative surgery with functional restoration of the salvaged limb.

Estrogen sulfotransferase (SULT1E1) expression in benign and malignant human bone tumors.

BACKGROUND AND OBJECTIVES: 17beta-estradiol regulates growth and differentiation in normal and malignant bone. E2 is inactivated to 17beta-estradiol-sulfate through estrogen sulfotransferase (SULT1E1). RESULTS: In an explorative study, SULT1E1 mRNA expression was assessed in a broad range of samples from benign, primary and secondary malignant bone tumors. We detected SULT1E1 mRNA in 31/50 tumor samples (10/19 malignant, 6/13 benign tumors; 15/18 metastases). Significantly more SULT1E1-positive samples were found in metastases than in primary bone tumors (P = 0.019). Yet, there was no difference between malignant and benign primary tumors (P = 0.718). SULT1E1 mRNA levels were not related to patients' age, gender, tumor location, stage, grading, and chemotherapy pretreatment. Relative SULT1E1 mRNA levels did not correlate with that of estrogen-receptor alpha (ERalpha) as assessed by quantitative TaqMan PCR (10 malignant, 8 benign tissue samples). In the latter, ERalpha mRNA, but not SULT1E1 mRNA levels were significantly lower than in the malignant samples (P = 0.006 and P = 0.71, respectively). Also, pronounced expression of SULT1E1 mRNA but not of ERalpha mRNA was observed in osteosarcoma (MG-63, HOS) and Ewing's sarcoma (TC-71) cells, while human osteoblasts and BMSC contained ERalpha but not SULT1E1 mRNA. CONCLUSION: Frequent expression of SULT1E1 mRNA in various human bone tumors suggests that sulfonation might be important to control E2 levels and activity.

Characteristics of ovine articular chondrocytes in a three-dimensional matrix consisting of different crosslinked collagen.

The purpose of this study was to evaluate the (ultra-) morphology, biochemical behavior, and activity of ovine chondrocytes seeded on a matrix consisting of three types of collagen (I, II, III) with two different degrees of UV crosslinking. Ovine articular chondrocytes were isolated from stifle joints and seeded on both types of UV-crosslinked collagen matrices, as well as on non-crosslinked sponges, and cultured for 12 h, 7 days, 14 days, and 21 days. Histological analysis, electron microscopy, biochemical assays for glycosaminoglycans, and real-time quantitative PCR for collagens were performed for cell-seeded and unseeded matrices. There was no dramatic difference in the morphology and bioactivity of the cells; however, concerning handling characteristics and integrative stability, both types of crosslinked sponges were superior to non-crosslinked constructs. The results demonstrate that ovine articular chondrocytes express their phenotype in a sponge consisting of collagen; furthermore, because of mechanical reasons, non-crosslinked matrices cannot be recommended for implantation in vivo.