Mono- versus polyaxial locking plates in distal femur fractures – a biomechanical comparison of the Non-Contact-Bridging- (NCB) and the PERILOC-plate

BACKGROUND: The aim of this cadaveric study was to compare a polyaxial (NCB®, Zimmer) to a fixed-angle monoaxial locking plate (PERILOC®, Smith & Nephew) in comminuted fractures of the distal femur regarding stability of the construct. Up to date there is no published biomechanical data concerning polyaxial plating in cadaveric distal femurs. METHODS: Fourteen formalin fixed femora were scanned by dual-energy x-ray absorptiometry. As fracture model an unstable supracondylar comminuted fracture was simulated. Fractures were pairwise randomly fixed either with a mono- (group A) or a polyaxial (group B) distal femur plate. The samples were tested in a servohydraulic mechanical testing system starting with an axial loading of 200 N following an increase of 200 N in every step with 500 cycles in every sequence up to a maximum of 2 000 N. The end points were implant failure or relevant loss of reduction. Data records included for each specimen time, number of cycles, axial load and axial displacement. Statistical analysis was performed using the exact Wilcoxon signed rank test. RESULTS: The mean donor age at the time of death was 75 years. The bone mass density (BMD) of the femurs in both groups was comparable and showed no statistically significant differences. Five bones failed before reaching the maximum applied force of 2000 N. Distribution curves of all samples in both groups, showing the plastic deformation in relation to the axial force, showed no statistically significant differences. CONCLUSIONS: Operative stabilization of distal femur fractures can be successfully and equally well achieved using either a monoaxial or a polyaxial locking plate. Polyaxial screw fixation may have advantages if intramedullary implants are present. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/1471-2474-15-369) contains supplementary material, which is available to authorized users

Standardizing Patient-Derived Organoid Generation Workflow to Avoid Microbial Contamination From Colorectal Cancer Tissues.

The use of patient-derived organoids (PDO) as a valuable alternative to in vivo models significantly increased over the last years in cancer research. The ability of PDOs to genetically resemble tumor heterogeneity makes them a powerful tool for personalized drug screening. Despite the extensive optimization of protocols for the generation of PDOs from colorectal tissue, there is still a lack of standardization of tissue handling prior to processing, leading to microbial contamination of the organoid culture. Here, using a cohort of 16 patients diagnosed with colorectal carcinoma (CRC), we aimed to test the efficacy of phosphate-buffered saline (PBS), penicillin/streptomycin (P/S), and Primocin, alone or in combination, in preventing organoid cultures contamination when used in washing steps prior to tissue processing. Each CRC tissue was divided into 5 tissue pieces, and treated with each different washing solution, or none. After the washing steps, all samples were processed for organoid generation following the same standard protocol. We detected contamination in 62.5% of the non-washed samples, while the use of PBS or P/S-containing PBS reduced the contamination rate to 50% and 25%, respectively. Notably, none of the organoid cultures washed with PBS/Primocin-containing solution were contaminated. Interestingly, addition of P/S to the washing solution reduced the percentage of living cells compared to Primocin. Taken together, our results demonstrate that, prior to tissue processing, adding Primocin to the tissue washing solution is able to eliminate the risk of microbial contamination in PDO cultures, and that the use of P/S negatively impacts organoids growth. We believe that our easy-to-apply protocol might help increase the success rate of organoid generation from CRC patients

Biomechanischer Stabilitätsvergleich am distalen Femur: retrograde Nagelung versus polyaxiale, winkelstabile Plattenosteosynthese

Die distale Femurfraktur ist eine sehr komplexe Fraktur, für die sich unterschiedliche Therapiemöglichkeiten anbieten. Neben intramedullären Kraftträgern stehen mit der neuesten Generation polyaxialer, winkelstabiler Plattenosteosynthesen auch adäquate extramedulläre Verfahren zur Verfügung. In der vorliegenden Arbeit soll der retrograde M/DN-Femurnagel (Fa. Zimmer) mit der polyaxialen NCB-DF Platte (Fa. Zimmer) hinsichtlich der biomechanischen Stabilität und Belastbarkeit verglichen werden. Verwendet wurden acht paarige, formalinfixierte Leichenfemora. Vorbestehende Frakturen und Osteolysen wurden mittels radiologischer Kontrolle ausgeschlossen. Ein standardisiertes Frakturmodel (AO 33-A3) mit einer Defektzone von 2 cm wurde etabliert. Nach der Randomisierung wurden je vier M/DN Femurnägel am rechten bzw. linken Knochen eines jeden Paares implantiert. Entsprechend wurde beim jeweiligen Gegenstück der Paare die NCB-DF Platte eingesetzt. Die Verriegelung erfolgte bei den Nägeln mit Hilfe horizontal zum Nagel eingebrachter Verriegelungsbolzen. Die Platte wurde durch Verschlusskappen verriegelt. Nach Einbetten der Femurkondylen in einen ca. 2 cm hohen Technovit-Sockel erfolgt die zyklische Druckbelastung in einer Materialprüfmaschine der Firma Instron (Modell 5566). Das standardisierte Prüfprotokoll sah den Beginn bei 1.000 N vor. Nach je 500 Zyklen wurde die Druckkraft um je 500 N bis zu einer maximalen Belastung von 5.000 N erhöht. Als Abbruchkriterien galten außerdem ein Druckkraftverlust von 20 % und eine Druckverformung > 30 mm. Alle Osteosynthesen hielten einer Druckkraft von mindestens 2.500 N stand. Unter dieser Belastung wurde eine mittlere plastische Verformung von 0,29 mm bei der Nagelosteosynthese und 0,76 mm bei der Plattenosteosynthese beobachtet. Der Unterschied in der plastischen Verformung ist auf dem Belastungsniveau von 2.500 N nicht signifikant (p=0,056). Eine mittlere plastische Gesamtverformung betrug beim Nagel 2,76 mm und bei der Platte 5,64 mm. Für die Druckverformung ergab sich bei 2.500 N ein signifikanter Unterschied mit p=0,0036. Die durchschnittliche Verformung betrug 1,99 mm (Nagelosteosynthese) und 3,99 mm (NCB-Plattenosteosynthese). Im Druckkraftbereich von 4.000 N – 5.000 N versagten je 5 Nagel- und 5 Plattenosteosynthesen. Dabei konnte kein signifikanter Unterschied festgestellt werden (p=0,943). Bei 3 von 8 Nagelosteosynthesen und 1 von 8 Plattenosteosynthesen kam es nicht zum Osteosyntheseversagen. Im Versagensfall riss bei den meisten Proben die proximale Verschraubung aus. Allein bei der Probe 2 mit NCB-Plattenosteosynthese kam es zum distalen Osteosyntheseversagen durch einen Kondylenbruch. Bei den Proben 3 und 4 der Plattenosteosynthese wurde ein Versagen durch plastische Deformierung erreicht. In dieser Studie konnte gezeigt werden, dass im geriatrischen Knochen beide Systeme eine ausreichende Primärstabilität, eine vergleichbare biomechanische Stabilität unter axialer, zyklischer Belastung sowie einander entsprechende Osteosyntheseversagen aufweisen. Hinsichtlich der Druckverformung unterscheiden sich Nagel- und. Plattenosteosynthese jedoch signifikant. Die NCB-Plattenosteosynthese manifestierte sich als das elastischere von beiden Systemen. In wie weit dieser Elastizitätsgewinn der NCB-Plattenosteosynthese im klinischen Alltag hinsichtlich der Frakturheilung von Vorteil ist, kann aus dem Studienaufbau nicht abgeleitet werden

Car-sharing organizations : The size of the market segment and revealed change in mobility behavior

Car-sharing organizations (CSO) have recently spread throughout central European cities and currently have 20000 members. They lower individual fixed costs of car availability change the incentive structure of private vehicle use by transforming nearly all costs into variable costs. A survey of all current Austrian CSO members is used to identify the characteristics significant of members. A procedure is proposed to quantify urban local market segment potentials and is applied to two residential areas. The net impact of CSOs depends on how the new incentive structure changes mobility behavior. A controlled experiment of voluntary new members was carried out to compare pre-membership and membership trip structure and modal split. Results indicate a substantial reduction of aggregate private vehicle mileage. While the share of trips by car is constant, changes in trip length are observed, with there being different changes for households which previously owned a car and those which did not. Combining behavior impact with market segment size results in the quantification of emission reduction and car ownership reduction (land use demand) due to car-sharing, which is a decentralized demand-side transport policy.

Reintervention rates following hallux valgus correction with the original and a modified Kramer osteotomy

 Numerous surgical techniques to correct hallux valgus deformities are performed worldwide, some of which were developed to address problems associated with existing techniques.  This retrospective study investigated patient’s outcomes and reintervention rates following the original Kramer osteotomy (KO) and a modified version of the KO (MKO). Results of radiological and clinical were gathered from medical records and long-term follow-up visits.  Angular measurements significantly improved and only three minor postoperative complications occurred after both procedures. No significant loss of correction was detected at long-term follow-up. The reintervention rate in the MKO group was 53% and the malalignment rate in the KO group was 18%.Despite promising angular results, both techniques had important weaknesses. MKO had a high reintervention rate, which was even more clinically problematic than malalignment after KO. Given the vast array of surgical techniques to treat this condition, we conclude that better performing options should be considered.

Results of titanium locking plate and stainless steel cerclage wire combination in femoral fractures

Background: Some in vitro studies warn combining different metals in orthopedic surgery. The aim of this study is to determine the impact of combining titanium and stainless steel on bone healing and the clinical course of patients undergoing internal fixation of femoral fractures. Materials and Methods: 69 patients with femoral fractures had polyaxial locking plate osteosynthesis. The locking plate was made of a titanium alloy. Two different cohorts were defined: (a) sole plating and (b) additional stainless steel cerclage wiring. Postoperative radiographs and clinical followup were performed at 6 weeks, 3 months and 12 months. Results: Cohorts A and B had 36 and 33 patients, respectively. Patient demographics and comorbidities were similar in both groups. In two cases in cohort A, surgical revision was necessary. No complication could be attributed to the combination of titanium and stainless steel. Conclusion: The combination of stainless steel cerclage wires and titanium plates does not compromise fracture healing or the postoperative clinical course

Perioperative blood transfusions in hip and knee arthroplasty: a retrospective assessment of combined risk factors

INTRODUCTION Accurate identification of patients at risk of blood transfusion can reduce complications and improve institutional resource allocation. Probabilistic models are used to detect risk factors and formulate patient blood management strategies. Whether these predictors vary among institutions is unclear. We aimed to identify risk factors among our patients who underwent total hip (THA) or knee (TKA) arthroplasty, and combine these predictors to improve our model. MATERIALS AND METHODS We retrospectively assessed risk factors among 531 adults who underwent elective THA or TKA from January 2016 to November 2018. Using relevant surgical and patient characteristics gathered from electronic medical records, we conducted univariable and multivariable analyses. For our logistic regression model, we measured the impact of independent variables (age, gender, operation type (THA or TKA) and preoperative hemoglobin concentration) on the need for a transfusion. RESULTS Of the 531 patients, 321 had THA (uncemented) and 210 had TKA. For the selected period, our transfusion rate of 8.1% (10.6% THA and 4.3% TKA) was low. Univariable analyses showed that lower BMI (p < 0.001) was associated with receiving a transfusion. Important factors identified through logistic regression analyses were age (estimated effect of an interquartile range increase in age: OR 3.89 [CI 95% 1.96-7.69]), TKA (OR - 0.77 [CI 95% - 1.57-0.02]), and preoperative hemoglobin levels (estimated effect of interquartile range increase in hemoglobin: OR 0.47 [CI 95% 0.31-0.71]). Contrary to findings from previous reports, gender was not associated with transfusion. CONCLUSIONS Previously published predictors such as advanced age, low preoperative hemoglobin, and procedure type (THA) were also identified in our analysis. However, gender was not a predictor, and BMI showed the potential to influence risk. We conclude that, when feasible, the determination of site-specific transfusion rates and combined risk factors can assist practitioners to customize care according to the needs of their patient population. LEVEL OF EVIDENCE Level 3, retrospective cohort study

Increased injury severity and hospitalization rates following crashes with e-bikes versus conventional bicycles: an observational cohort study from a regional level II trauma center in Switzerland

BACKGROUND As electric bicycles (e-bikes) become increasingly popular, reports of injuries associated with e-bike usage are also rising. Patterns, characteristics, and severity of injuries following e-bike crashes need further investigation, particularly in contrast to injuries from conventional bicycle crashes. METHODS This prospective observational study included 82 patients treated at a Level II trauma center for injuries resulting from an electric or conventional bicycle crash. Data were collected over one year (05.09.2017-19.09.2018) during in- and outpatient visits. A study-specific case report form was used to identify the bicycle type, cycling behavior (e.g., use of a helmet, safety gear, alcohol), and circumstances of the crash (e.g., road conditions, speed, cause of the incident, time of day, season). Additional information about patient demographics, treatment, and injury characteristics, such as the Injury Severity Score (ISS) and body region injured, were documented. Results were analyzed using chi-square, Fisher's exact, or Wilcoxon tests. Simple logistic or linear regression models were used to estimate associations. RESULTS Of the 82 patients, 56 (67%) were riding a conventional bike and 27 (33%) were using an e-bike. Most incidents were either single-bicycle crashes (66%) or automobile collisions (26%), with no notable difference in prevalence rates between groups. Although a higher proportion of conventional bikers were male (67% vs. 48%), the difference was not significant. E-bikers were older (median 60 years (IQR 44-70) vs. 45 years (IQR 32-62); p = 0.008), were hospitalized more often (48% vs. 24%, p = 0.025), and had worse ISS (median 3 (IQR 2-4) vs. 1 (IQR 1-3), p < 0.001), respectively. Body regions most affected were the extremities (78%) and external/skin (46%), and these were distributed similarly in both groups. Concomitant injury patterns of the thorax/chest with external/skin were higher among e-bikers (p < 0.001). When we controlled for the difference in the median age of the two groups, only the injury severity score of e-bikers remained significantly worse. CONCLUSIONS Hospitalization and chest trauma rates were higher among e-bikers. After controlling for the older age of this group, the severity of their injuries remained worse than in conventional cyclists. Initial clinical assessments at trauma units should include an evaluation of the thorax/chest, particularly among elderly e-bikers. LEVEL OF EVIDENCE Level III