Purpose
Many studies have shown that local anesthetics may impede chondrocyte metabolism. However, the influence of a single-dose local anesthetics is controversial. The aim of this metaanalysis was ...to review the literature for studies investigating the cytotoxic effects of single-dose local anesthetics on chondrocytes and cartilage.
Methods
A comprehensive literature search was performed using established search engines (Medline, Embase) to identify studies, investigating the influence of single-dose local anesthetics on cartilage. The systematic analysis included the influence on histology, cell viability, morphology, and matrix production depending upon dose, exposure time, and type of local anesthetics.
Results
Twelve studies with four different local anesthetics were included in this metaanalysis. Bupivacaine and lidocaine were found to be more chondrotoxic than mepivacaine and ropivacaine. The amount of dead cells increased in a substance-, dose-, and time-dependent process. Osteoarthritic cartilage seems to be more vulnerable compared to intact cartilage. The toxic effects occur first in the superficial cartilage layers and include damage to membrane integrity, mitochondrial DNA, and nuclear changes. There is no study that could show a significant chondrotoxic effect with low concentrations of bupivacaine (0.0625%), ropivacaine (0.1 and 0.2%), and mepivacaine (0.5%).
Conclusions
The cytotoxicity of local anesthetics on chondrocytes is dependent on dose, time, and type of local anesthetics. Single-dose intra-articular administration of local anesthetics impede chondrocyte metabolism and should be performed only with low concentrations for selected diagnostic purposes and painful joints. The use of lidocaine should be avoided.
Level of evidence
II.
Purpose
For the new generation of mandibular reconstruction, patient-specific mandible reconstruction plates (PSMPs) have been developed which are milled from titanium after preoperative computer ...planning using CAD/CAM procedures. Resection margins and plate position are determined by surgical guides. In addition, length and shape of the plate and the number and angulation of the screw holes can be planned.
Methods
30 patients received such PSMP. Indication ranged from stabilization osteosynthesis, single alloplastic stand-alone reconstruction to microvascular reconstructions. Time for planning, fit of surgical guides and plates, pre-/postoperative occlusion, radiological position of the temporo mandibular joint and complications were recorded.
Results
The median time for online planning was 35 min. The results concerning fit and handling of the PSMP and the surgical guides were mainly very positive. In six cases, the plan had to be adapted to the intraoperative clinical needs. The postoperative position of the condyles in the temporo mandibular fossae was regular in 28 cases. The evaluation of the occlusion was not representative due to not clearly identifiable occlusion in 2/3 of the cases. Nevertheless, complications like postoperative extraoral plate exposure, infection, graft and flap necrosis or difficulties to position the guides or the plate during surgery occurred.
Conclusions
Mandibular reconstruction with PSMP offers a broad range of opportunities and benefits compared with standard procedures and can be recommended for all kind of mandibular reconstructions. It is not yet foreseeable whether PSMP will in future become routine clinical practice for mandibular reconstruction or will be confined to selected isolated cases.
Purpose
Virtual reconstruction of large cranial defects is still a challenging task. The current reconstruction procedures depend on the surgeon’s experience and skills in planning the reconstruction ...based on mirroring and manual adaptation. The aim of this study is to propose and evaluate a computer-based approach employing a statistical shape model (SSM) of the cranial vault.
Methods
An SSM was created based on 131 CT scans of pathologically unaffected adult crania. After segmentation, the resulting surface mesh of one patient was established as template and subsequently registered to the entire sample. Using the registered surface meshes, an SSM was generated capturing the shape variability of the cranial vault. The knowledge about this shape variation in healthy patients was used to estimate the missing parts. The accuracy of the reconstruction was evaluated by using 31 CT scans not included in the SSM. Both unilateral and bilateral bony defects were created on each skull. The reconstruction was performed using the current gold standard of mirroring the intact to the affected side, and the result was compared to the outcome of our proposed SSM-driven method. The accuracy of the reconstruction was determined by calculating the distances to the corresponding parts on the intact skull.
Results
While unilateral defects could be reconstructed with both methods, the reconstruction of bilateral defects was, for obvious reasons, only possible employing the SSM-based method. Comparing all groups, the analysis shows a significantly higher precision of the SSM group, with a mean error of 0.47 mm compared to the mirroring group which exhibited a mean error of 1.13 mm. Reconstructions of bilateral defects yielded only slightly higher estimation errors than those of unilateral defects.
Conclusion
The presented computer-based approach using SSM is a precise and simple tool in the field of computer-assisted surgery. It helps to reconstruct large-size defects of the skull considering the natural asymmetry of the cranium and is not limited to unilateral defects.
Background
Acute kidney injury is a serious complication following cardiac surgery associated with mortality. Restricted oxygen delivery is a potential risk factor for acute kidney injury. The aim of ...this study was to investigate the impact of the duration of low oxygen delivery (<272 mL min−1 m−2), during cardiopulmonary bypass on kidney function.
Methods
Patients undergoing coronary artery bypass graft surgery ± valve repair were included n = 1968. Oxygen delivery was monitored during cardiopulmonary bypass. Data were explored using multiple regression analyses regarding association between low oxygen delivery and renal replacement therapy (RRT), acute kidney injury (AKI) and post‐operative peak serum creatinine (PPSC).
Results
Post‐operative peak serum creatinine, incidence of acute kidney injury, and need for dialysis increased in a dose‐dependent manner in relation to duration of a mean oxygen delivery <272 mL min−1 m−2. Using multiple regression analyses, only exposure for at least 30 minutes was independently associated with increased PPSC and AKI. In contrast, both short (1‐5 min, OR: 2.58 1.20, 5.54; P = .015) and at least 30‐minute (OR: 2.85 1.27‐6.41; P = .011) exposure to low DO2 were both independently associated with the need for RRT.
Conclusion
A low oxygen delivery during cardiopulmonary bypass was in a dose‐dependent manner associated with an increased risk of renal injury.
Purpose To evaluate the chondrogenic potential of platelet concentrates on human subchondral mesenchymal progenitor cells (MPCs) as assessed by histomorphometric analysis of proteoglycans and type II ...collagen. Furthermore, the migratory and proliferative effect of platelet concentrates were assessed. Methods Platelet-rich plasma (PRP) was prepared using preparation kits (Autologous Conditioned Plasma ACP Kit Arthrex, Naples, FL; Regen ACR-C Kit Regen Lab, Le Mont-Sur-Lausanne, Switzerland; and Dr.PRP Kit Rmedica, Seoul, Republic of Korea) by apheresis (PRP-A) and by centrifugation (PRP-C). In contrast to clinical application, freeze-and-thaw cycles were subsequently performed to activate platelets and to prevent medium coagulation by residual fibrinogen in vitro. MPCs were harvested from the cortico-spongious bone of femoral heads. Chondrogenic differentiation of MPCs was induced in high-density pellet cultures and evaluated by histochemical staining of typical cartilage matrix components. Migration of MPCs was assessed using a chemotaxis assay, and proliferation activity was measured by DNA content. Results MPCs cultured in the presence of 5% ACP, Regen, or Dr.PRP formed fibrous tissue, whereas MPCs stimulated with 5% PRP-A or PRP-C developed compact and dense cartilaginous tissue rich in type II collagen and proteoglycans. All platelet concentrates significantly (ACP, P = .00041; Regen, P = .00029; Dr.PRP, P = .00051; PRP-A, P < .0001; and PRP-C, P < .0001) stimulated migration of MPCs. All platelet concentrates but one (Dr.PRP, P = .63) showed a proliferative effect on MPCs, as shown by significant increases (ACP, P = .027; Regen, P = .0029; PRP-A, P = .00021; and PRP-C, P = .00069) in DNA content. Conclusions Platelet concentrates obtained by different preparation methods exhibit different potentials to stimulate chondrogenic differentiation, migration, and proliferation of MPCs. Platelet concentrates obtained by commercially available preparation kits failed to induce chondrogenic differentiation of MPCs, whereas highly standardized PRP preparations did induce such differentiation. These findings suggest differing outcomes with PRP treatment in stem cell–based cartilage repair. Clinical Relevance Our findings may help to explain the variability of results in studies examining the use of PRP clinically.
To assess the accuracy with which CAD/CAM-fabricated patient-specific titanium implants (PSI) are positioned for inferior and/or medial orbital wall reconstruction without the use of intraoperative ...navigation.
Patients who underwent a primary reconstruction of the orbital walls with PSI due to fractures were enrolled in this retrospective cohort analysis. The primary outcome variables were the mean surface distances (MSD) between virtually planned and postoperative PSI position and single linear deviations in the x-, y- and z-axis at corresponding reference points. Secondary outcome variables included demographic data, classification of orbital wall defects and clinical outcomes.
A total of 33 PSI (orbital floor n = 22; medial wall, n = 11) were examined in 27 patients. MSD was on a comparable level for the orbital floor and medial wall (median 0.39 mm, range 0.22–1.53 mm vs. median 0.42 mm, range 0.21–0.98 mm; p = 0.56). Single linear deviations were lower for reconstructions of the orbital floor compared to the medial wall (median 0.45 vs. 0.79 mm; p < 0.05). There was no association between the occurrence of diplopia and the accuracy level (p = 0.418).
Free-hand positioning of PSI reaches a clinically appropriate level of accuracy, limiting the necessity of navigational systems to selected cases.
•Accuracy with which CAD/CAM-fabricated patient-specific titanium implants are positioned for orbital wall reconstruction.•Geometric deviation between virtually planned and postoperative PSI position.•Freehand positioning of PSI for orbital wall reconstruction is accurate.•Navigation systems are not mandatory for orbital wall reconstruction.
Objective
Since MRI using dedicated imaging sequences has recently shown promising results in direct visualization of the inferior alveolar nerve (IAN) and the lingual nerve (LN) with high spatial ...resolution, the aim of this study was to generate suitable standard specifications to reliably depict the IAN and LN in MRI and to delineate the anatomy and its variants of these nerves in healthy subjects.
Methods
Thirty healthy volunteers were examined on a 3-T scanner (Elition, Philips Healthcare, Best, the Netherlands). The sequence protocol consisted of 3D STIR, 3D DESS, and 3D T1 FFE “black bone” sequences.
Results
The study reconfirmed a good feasibility of direct visualization of proximal and peripheral portions of the IAN and of the proximal course of the LN. The STIR sequence showed the highest apparent signal to noise ratio (aSNR) and best apparent nerve-muscle contrast to noise ratio (aNMCNR) for IAN and for the LN. The applied MRI sequences allowed to differentiate the tissue composition of the neurovascular bundle inside the mandibular canal.
Conclusion
Dedicated MRI sequence protocols proved effectively to detect the IAN and LN and their course in healthy volunteers. The tissue composition of the mandibular neurovascular bundle was conclusively distinguishable as was the varying topography inside multiple bony channels.
Clinical relevance
The presented data on the precise and valid visualization of the IAN and LN have clinical implications in respect to local anesthesia prior to dental treatments in the mandible but also regarding surgical procedures and implant insertion in the molar region.
Abstract Purpose This study evaluates the accuracy of a statistical shape model (SSM) for virtual fracture reconstruction of the lateral midface. Materials and methods A uniform bony defect of the ...right zygoma was created. A virtual reconstruction was performed by using the standard procedure of mirroring the unaffected to the affected side (Group I) and by using the statistical model based on 178 pathologically unaffected CT scans (Group II). The accuracy of the statistical shape model was evaluated in comparison to the present mirroring protocol. The reconstructed region was compared with the original bone evaluating the mean deviation of both surfaces. Results All zygomas could be reconstructed with all methods. On the affected side the mean deviation was 1.10 mm ± 0.23 mm in group I and 0.85 mm ± 0.26 mm in group II. The differences between the groups were significant. Conclusion SSM offers a more precise reconstruction of midface defects than mirroring procedures. As an additional element SSM could automatize the CAS workflow in many respects.
Objective The aim of the study was to determine the clinical efficacy of maxillofacial cone-beam computed tomography (CBCT) for the diagnosis of suspected mandibular fractures and to evaluate whether ...findings would lead to a change in treatment. Study design CBCT imaging was performed for 164 patients with suspected mandibular fractures (231 sites) but equivocal clinical and radiological findings (conventional radiography). Images were interpreted by oral and maxillofacial surgeons and treatment decisions based on pre and postimaging were compared. Linear regression analyses were performed. Results For 63.2% of sites ( n = 146) the suspected diagnosis was confirmed by CBCT ( P < .0001; R2 = 0.93). For 4.33% of sites ( n = 10) no fracture was identified. Additional fractures were identified in 17.75% ( n = 41) and additional infractures in 14.72% ( n = 34). The treatment plan was altered for 9.52% of sites ( n = 22). Conclusions CBCT imaging of suspected mandibular fractures resulted in a change in the treatment plan in 9.52%.
The known preformed osteosynthesis plates for the midface are helpful tools for a precise and fast fixation of repositioned fractures. The purpose of the current study is to analyze the precision of ...newly developed prototypes of preformed osteosynthesis plates for the mandible.
Four newly designed preformed osteosynthesis plates, generated by a statistical shape model based on 115 CT scans, were virtually analyzed. The used plates were designed for symphyseal, parasymphyseal, angle, and condyle fractures. Each type of plate has three different sizes. For analysis, the shortest distance between the plate and the bone surface was measured, and the sum of the plate-to-bone distances over the whole surface was calculated.
A distance between plate and bone of less than 1.5 mm was defined as sufficient fitting. The plate for symphyseal fractures showed good fitting in 90% of the cases for size M, and in 84% for size L. For parasymphyseal fractures, size S fits in 80%, size M in 68%, and size L in 65% of the cases. Angle fractures with their specific plate show good fitting for size S in 53%, size M in 60%, and size L in 47%. The preformed plate for the condyle part fits for size S in 75%, for size M in 85%, and for size L in 74% of the cases.
The newly developed mandible plates show sufficient clinical fitting to ensure adequate fracture reduction and fixation.
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