Abstract Objective The best material choice for cranioplasty following craniectomy remains subject to discussion. Complication rates after cranioplasty tend to be high. Computer-assisted ...3-dimensional modeling of polyetheretherketone (PEEK) was recently introduced for cranial reconstruction. The aim of this study was to evaluate patient- and surgery-related characteristics and risk factors that predispose patients to cranioplasty complications. Material and methods This retrospective study included a total of 40 cranial PEEK implants in 38 patients, performed at two reference centers in the Netherlands from 2011 to 2014. Complications were registered and patient- and surgery-related data were carefully analysed. Results The overall complication rate of PEEK cranioplasty was 28%. Complications included infection (13 %), postoperative hematoma (10 %), cerebrospinal fluid leak (2.5 %) and wound-related problems (2.5 %). All postoperative infections required removal of the implant. Nonetheless removed implants could be successfully re-used after re-sterilization. Conclusion Although overall complication rates after PEEK cranioplasty remain high, outcomes are satisfactory, as our results compare favourably to recent literature reports on cranial vault reconstruction.
Background
Cerebrospinal fluid (CSF) leakage represents an important and sometimes challenging complication in both cranial and spinal surgery. Current available options for dural closure pose ...inherent problems regarding safety, efficacy, immunogenicity, cost, and invasiveness. In this article, the use of leukocyte- and platelet-rich fibrin (L-PRF) derived from the patient’s own blood is proposed to facilitate dural closure. We aim to describe the safety, feasibility, and applicability of L-PRF membranes and plugs in cranial and spinal neurosurgery.
Methods
A retrospective study reviewing clinical and surgical characteristics was conducted in 47 patients in whom the use of L-PRF was attempted to reinforce dural closure at a single institution during 1 year. Procedures included skull base, posterior fossa, and spinal revision surgeries.
Results
L-PRF membranes and/or plugs were used in 44 surgeries. The preparation of L-PRF failed in three cases. L-PRF membranes were used as onlay grafts to augment sealing or sutured into a defect. No short-term complications related to the use of L-PRF were recorded. Postoperative CSF leakage was present in two endoscopic transsphenoidal pituitary surgeries and in one spinal CSF leak repair.
Conclusion
L-PRF is safe, inexpensive, and completely autologous and can be rapidly and non-invasively harvested to aid in dural closure. Theoretical advantages include a regenerative bioactive potential, which could lead to improved wound healing and reduced infection rates. These findings warrant larger prospective studies to determine the potential role of L-PRF in neurosurgery.
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Recent developments suggest that the phase transition of natural and synthetic biomacromolecules represents an important and ubiquitous mechanism underlying structural assemblies ...toward the fabrication of high-performance materials. Such a transition results in the formation of condensed liquid droplets, described as condensates or coacervates. Being able to effectively control the assembly of such entities is essential for tuning the quality and their functionality. Here we describe how self-coacervation of genetically engineered spidroin-inspired proteins can be preceded by a wide range of kosmotropic salts. We studied the kinetics and mechanisms of coacervation in different conditions, from direct observation of initial phase separation to the early stage of nucleation/growth and fusion into large fluid assemblies. We found that coacervation induced by kosmotropic salts follows the classical nucleation theory and critically relies on precursor clusters of few weak-interacting protein monomers. Depending on solution conditions and the strength of the supramolecular interaction as a function of time, coacervates with a continuum of physiochemical properties were observed. We observed similar characteristics in other protein-based coacervates, which include having a spherical-ellipsoid shape in solution, an interconnected bicontinuous network, surface adhesion, and wetting properties. Finally, we demonstrated the use of salt-induced self-coacervates of spidroin-inspired protein as a cellulosic binder in dried condition.
Purpose
Debate remains whether posterior implants after thoracolumbar spine fracture stabilization should be removed routinely or only in symptomatic cases. Implant related problems might be resolved ...or even prevented but removal includes secondary risks. The aim of this study was to evaluate safety, patient satisfaction and quality of life after implant removal.
Methods
A retrospective cohort study was performed concerning 102 patients that underwent posterior implant removal after stabilization of a traumatic thoracolumbar fracture between 2003 and 2015. Patients were invited to fill in SF-36, EQ-5D and RMDQ questionnaires after implant removal. Additionally, questions concerning satisfaction were presented. Cobb angles before and after removal were measured and in- or decrease of symptoms was gathered from hospital charts.
Results
Mean age at removal was 38 years and time from implant removal to questionnaire was approximately 7 years, 62 patients filled in the questionnaires. Complications were present in 8% and quality of life was reported as fairly good. Patients had less back pain related disability compared to chronic low back pain patients. After removal there was a kyphosis increase which did not correspond with worsened clinical outcome. Removal decreased most symptoms and even asymptomatic patients reported benefit in most cases. An increase of symptoms after removal was reported in 11% of patients.
Conclusion
Implant removal is generally safe and provides high patient satisfaction. Overall, patients have a fairly good quality of life. Most symptomatic and asymptomatic patients report benefit from removal. However, low risks of complications and increase of symptoms have to be weighted for individual patients.
Following the events of September 11, 2001, in the United States, world public awareness for possible terrorist attacks on water supply systems has increased dramatically. Among the different threats ...for a water distribution system, the most difficult to address is a deliberate chemical or biological contaminant injection, due to both the uncertainty of the type of injected contaminant and its consequences, and the uncertainty of the time and location of the injection. An online contaminant monitoring system is considered as a major opportunity to protect against the impacts of a deliberate contaminant intrusion. However, although optimization models and solution algorithms have been developed for locating sensors, little is known about how these design algorithms compare to the efforts of human designers, and thus, the advantages they propose for practical design of sensor networks. To explore these issues, the Battle of the Water Sensor Networks (BWSN) was undertaken as part of the 8th Annual Water Distribution Systems Analysis Symposium, Cincinnati, Ohio, August 27–29, 2006. This paper summarizes the outcome of the BWSN effort and suggests future directions for water sensor networks research and implementation.
•Aligning trans-tibial prostheses by a predetermined kinetic criterion is eligible.•Induced alignment changes didn’t affect spatiotemporal and kinematic gait parameters.•Prosthetic alignment changes ...had variable effects on knee moments and socket comfort.•The usability of External Socket Reaction Moments in the clinic is currently limited.
Prosthetic alignment is used to optimize prosthetic functioning and comfort. Spatio-temporal and kinematic gait parameters are generally observed to guide this process. However, they have been shown to be influenced by compensations, which reduces their sensitivity to changes in alignment. Alternatively, the use of moments working at the base of the prosthetic socket, external socket reaction moments (ESRM), has been proposed to quantify prosthetic alignment.
To investigate if a predetermined kinetic alignment criterion, 0Nm averaged over the stance phase, can be used to fine-tune prosthetic alignment.
10 transtibial amputees were included in this intervention study. Firstly, their prostheses were aligned using conventional alignment procedures. Kinetic parameters and Socket Comfort Score (SCS) were measured in this initial alignment (IA) condition. Subsequently, the coronal plane ESRM during gait was presented to the prosthetist in real time using a Gait Real-time Analysis Interactive Lab. The prosthetist iteratively adapted the prosthetic alignment towards a predetermined average ESRM during the stance phase of 0 Nm. At the Final Alignment (FA), kinetic parameters and SCS were measured again and a paired sample t-test was performed to compare ESRMs and SCSs between alignments.
A significant (p < 0.001) change was found in the absolute coronal plane ESRM (mean ± SD) from IA (|0.104| ± 0.058 Nm/kg) to FA (|0.012| ± 0.015 Nm/kg). In addition a significant (p < 0.001) change of the external coronal adduction knee moments was observed from IA (−0,127 ± 0.079 Nm/kg) to FA (−0.055 ± 0.089 Nm/kg), however this change was more variable among participants. On average, no significant (p = 0.37) change in the SCS was observed.
While this study shows the potential of quantifying and guiding alignment with the assistance of kinetic criteria, it also suggests that a sole reliance on the ESRM as a single alignment criterion might be too simple.
Producing hydrogels capable of mimicking the biomechanics of soft tissue remains a challenge. We explore the potential of plant-based hydrogels as polysaccharide tragacanth gum and antioxidant lignin ...nanoparticles in bioactive multicomponent hydrogels for tissue engineering. These natural components are combined with TEMPO-oxidized cellulose nanofibrils, a material with known shear thinning behavior. Hydrogels presented tragacanth gum (TG) concentration-dependent rheological properties suitable for extrusion 3D printing. TG enhanced the swelling capacity up to 645% and the degradation rate up to 1.3%/day for hydrogels containing 75% of TG. Young's moduli of the hydrogels varied from 5.0 to 11.6 kPa and were comparable to soft tissues like skin and muscle. In vitro cell viability assays revealed that the scaffolds were non-toxic and promoted proliferation of hepatocellular carcinoma HepG2 cells. Therefore, the plant-based hydrogels designed in this work have a significant potential for tissue engineering.
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•3D printed hydrogels made of cellulose nanofibrils, lignin nanoparticles, and tragacanth gum were developed and characterized•Tragacanth gum enhanced rheological properties, swelling ratio, and degradation rate•Hydrogels presented no toxicity and promoted proliferation of HepG2 cells•Potential application of plant-based materials in tissue engineering
There has been a recent resurgence of interest in arthroscopic primary repair of proximal anterior cruciate ligament (ACL) tears. Patient selection is critical but not much is currently known on what ...predicts the possibility of repair. Goal of this study was therefore to assess predictive factors for the possibility of arthroscopic primary ACL repair.
In this retrospective case–control study, all patients undergoing ACL surgery in a ten-year interval were included. Patients were treated with primary repair if there was a proximal tear and good tissue quality, or otherwise underwent ACL reconstruction. Collected data were age, gender, BMI, injury-to-surgery delay, injury mechanism and concomitant injuries. Receiver operating characteristic curves were used to find cutoff values, and all significant dependent variables were used in multivariate logistic analysis to assess independent predictors for the possibility of primary repair.
Three hundred sixty-one patients were included, of which in 158 patients (44%) primary repair was possible. Multivariate analysis (R2 = 0.340, p < 0.001) showed that age > 35 years (Odds ratio OR 4.2, 95% CI 2.4–7.5,p < 0.001), surgery within 28 days (OR 3.3, 95% CI 1.9–5.7, p < 0.001), and BMI <26 (OR 1.9, 95% CI 1.1–3.3,p = 0.029) were predictive for the possibility of primary repair, and lateral meniscus injury presence decreased the likelihood of repair (OR 0.5, 95% CI 0.3–0.8, p = 0.008).
In this large cohort study, it was noted that 44% of patients had repairable ACL tears. Primary repair was more likely to be possible in older patients, patients with lower BMI and when surgery was performed within four weeks of injury.
meta-Iodobenzyl guanidine (MIBG) combines the structural properties of the neuron-blocking agents bretylium and guanethidine and is being used increasingly for various clinical applications. ...Different samples of MIBG were assayed for possible contamination with benzyl guanidine (BG). Fast-atom-bombardment mass spectrometry (FAB-MS) analysis showed a prominent but variable m/z 150 signal, corresponding to a protonated BG. The MS/MS fragmentation pattern of these M + H+ ions was similar to that obtained from FAB-MS-generated, protonated BG, confirming the proposed molecule and associated structures. RP-HPLC analysis of both guanidines, however, excluded the possibility of contamination of MIBG with BG. It was therefore concluded that the BG signal was an artifact of the FAB-MS procedure. In addition, the importance of the meta-substituted iodine for the biological activity of MIBG was investigated. Three different biochemical and cell-biological properties of MIBG were compared with those of its precursor MIBA and BG. The assays used were: inhibition of the catecholamine "Uptake I" system in SK-N-SH neuroblastoma and PC-12 pheochromocytoma cells, inhibition of mitochondrial respiration, and general cytotoxicity in L1210 leukemia cells. Of the drugs tested, MIBG was the most efficient in Uptake I inhibition and was more toxic in survival assays, but as compared with BG it was almost equipotent in inhibiting mitochondrial respiration. These findings contribute to a further elucidation of the mechanism by which MIBG exerts its various actions.
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