Reproducible Fixation Research Articles

Long term results and patient reported outcome measures following lisfranc injuries treated with memory staple fixation

IntroductionVarious modalities of fixation have been proposed for Lisfranc injuries. Memory staple fixation offers a simple option for transarticular fixation in suitable fracture configuration with no diaphyseal extension. However there is little evidence available in the literature regarding its efficacy and patient reported outcomes. Aim of the study was to present the long term outcomes of Lisfranc injuries treated with memory staple fixation and patient reported outcomes at average follow-up of four years. MethodThis was a retrospective analysis of all the patients who underwent fixation for Lisfranc injury using shape memory alloy (Nitinol) staples from December 2010 to October 2018. Patient demography, mechanism of injury, classification of Lisfranc injury, duration of followup, complication, revision surgery, implant removal and patient reported outcomes (AOFAS midfoot score) was noted. Results31 patients satisfied the inclusion criteria. Mean age was 50 years and 17 patients were females. 54 % patients reported low to moderate energy trauma which included simple fall from standing height or twisting injury. 28 (90.3 %) had B2 type of fracture pattern. 13 had fixation with staples only, 15 with a staple and home run screw. No patient had primary fusion. One patient had superficial infection treated with antibiotics only. Three patients developed symptomatic arthritis, out of which one proceeded to fusion. Six had implant removal for hardware related symptoms. Average AOFAS midfoot score at average four years follow-up was 77.8 which are satisfactory. ConclusionThis paper highlights good outcome following memory staple fixation for Lisfranc injuries. We believe staples are more suited for the dorsal buttressing that is typically required and provide stable, reproducible fixation Our findings also suggest less need for implant removal compared to transarticular screw or plate fixation though larger studies would be required to make definitive conclusions.

Tuberosity union in patients with proximal humerus fractures treated with reverse shoulder arthroplasty: a technical note and exploratory analysis.

The use of reverse shoulder arthroplasty (RSA) to treat complex humerus fractures is increasing, especially in older, osteoporotic patients. Refixation and tuberosity healing are needed to achieve an optimal range of motion (ROM), external rotation, active forward elevation, and patient satisfaction. Proper healing has been reported, however, in only 40-84% of cases. Our study's aim was to describe a simple, reproducible fixation technique designed to improve tuberosity healing. We included 30 patients with acute proximal humerus fractures undergoing RSA (Global Unite Reverse Fracture, DePuy Synthes, Warsaw, IN, USA) with tuberosity reattachment. The humerus stem was cemented in 24 cases. A standardized suture technique with two fiber tapes was used to reattach tuberosities. Clinical and radiological parameters, which were collected one year post-operatively, included ROM, pain level, Constant scores, subjective shoulder value (SSV), and tuberosity healing. The mean age of the patients was 79.3years (± 7; range 65-92), and the tuberosity healing rate was 90.0% (27 of 30). Two patients showed migration (one nonunion, one malunion), and another had complete resorption after an initial period of proper healing. Radiolucent lines around the humerus stem occurred in one case, and three patients had scapular notching. The mean SSV was 86% (± 11; range 60-100), the Constant score was 72 (± 10.3; range 48-92), the active forward flexion was 140° (± 14.3; range 115-165), and external rotation was 23° (± 16.5; range 0-50). This reattachment technique, which is simple and reproducible, achieved a higher tuberosity healing rate than previously published rates.

Optimal Screw Fixation of Syndesmosis Using a Targeting Drill Guide: A Technical Note

Optimal screw fixation of the syndesmosis is difficult. We introduce a novel technique using a targeting drill guide for centroidal screw fixation of a syndesmosis to ensure a reproducible and optimal screw trajectory for syndesmosis fixation. By using a drill guide for anterior cruciate ligament surgery and intraoperative fluoroscopy, syndesmosis fixation enables reproducible fixation along an individual centroidal axis.

The Influence of Contamination and Cleaning on the Strength of Modular Head Taper Fixation in Total Hip Arthroplasty

BackgroundIntraoperative interface contamination of modular head-stem taper junctions of hip implants can lead to poor fixation strength, causing fretting and crevice corrosion or even stem taper fracture. Careful cleaning before assembly should help to reduce these problems. The purpose of this study was to determine the effect of cleaning (with and without drying) contaminated taper interfaces on the taper fixation strength. MethodsMetal or ceramic heads were impacted onto titanium alloy stem tapers with cleaned or contaminated (fat or saline solution) interfaces. The same procedure was performed after cleaning and drying the contaminated interfaces. Pull-off force was used to determine the influence of contamination and cleaning on the taper strength. ResultsPull-off forces after contamination with fat were significantly lower than those for uncontaminated interfaces for both head materials. Pull-off forces after application of saline solution were not significantly different from those for uncontaminated tapers. However, a large variation in taper strength was observed, pull-off forces for cleaned and dried tapers were similar to those for uncontaminated tapers for both head materials. ConclusionIntraoperative contamination of taper interfaces may be difficult to detect but has a major influence on taper fixation strength. Cleaning of the stem taper with saline solution and drying with gauze directly before assembly allows the taper strength of the pristine components to be achieved. Not drying the taper results in a large variation in pull-off forces, emphasizing that drying is essential for sufficient and reproducible fixation strength.

Instillation and Fixation Methods Useful in Mouse Lung Cancer Research

The ability to instill live agents, cells, or chemicals directly into the lung without injuring or killing the mice is an important tool in lung cancer research. Although there are a number of methods that have been published showing how to intubate mice for pulmonary function measurements, none are without potential problems for rapid tracheal instillation in large cohorts of mice. In the present paper, a simple and quick method is described that enables an investigator to carry out such instillations in an efficient manner. The method does not require any special tools or lighting and can be learned with very little practice. It involves anesthetizing a mouse, making a small incision in the neck to visualize the trachea, and then inserting an intravenous catheter directly. The small incision is quickly closed with tissue adhesive, and the mice are allowed to recover. A skilled student or technician can do instillations at an average rate of 2 min/mouse. Once the cancer is established, there is frequently a need for quantitative histologic analysis of the lungs. Traditionally pathologists usually do not bother to standardize lung inflation during fixation, and analyses are often based on a scoring system that can be quite subjective. While this may sometime be sufficiently adequate for gross estimates of the size of a lung tumor, any proper stereological quantification of lung structure or cells requires a reproducible fixation procedure and subsequent lung volume measurement. Here we describe simple reliable procedures for both fixing the lungs under pressure and then accurately measuring the fixed lung volume. The only requirement is a laboratory balance that is accurate over a range of 1 mg-300 g. The procedures presented here thus could greatly improve the ability to create, treat, and analyze lung cancers in mice.

Reproducible fixation with a tapered, fluted, modular, titanium stem in revision hip arthroplasty at 8–15 years follow-up

The use of tapered, fluted, modular, distally fixing stems has increased in femoral revision surgery. The goal of this retrospective study was to assess mid-term to long-term outcomes of this implant. Seventy-one hips in 70 patients with a mean age of 69years were followed for an average of 10years. Preoperative HHS averaged 50 and improved to 87 postoperatively. Seventy-nine percent hips had Paprosky type 3A or more bone-loss. All stems osseointegrated distally (100%). Two hips subsided >5mm but achieved secondary stability. Sixty-eight percent hips had evidence of bony reconstitution and 21% demonstrated diaphyseal stress-shielding. One stem fractured near its modular junction and was revised with a mechanical failure rate of 1.4%. Distal fixation and clinical improvement were reproducibly achieved with this stem design.

Clinical Outcomes of γ-ray Stereotactic Body Radiation Therapy for Patients With Primary Hepatic Carcinoma of Stage I/II

To evaluate the effects and radiation reaction of patients of primary hepatic carcinoma of I/II stage by the stereotactic body radiation therapy. Fifty-two patients of stage I/II primary hepatic carcinoma were treated with the γ-ray stereotactic body radiation therapy (γ-ray SBRT, stereotactic gamma ray body radiotherapeutic system , body γ-knife), including 10 patients of stage I and 42 patients of stage II. For γ-SBRT a stereotactic body frame for exact tumor localization, reproducible fixation, CT simulation, and 3-D treatment plan has been developed. A three dimensional margin of 1cm were added to GTV. Fifty percent isodose line was prescription dose line and covered 100% area of PTV and 70% isodose line covered more than 80% area of GTV. According to the tumors size, position and function of the liver, they were irradiated 3-5 Gy per fraction at 50% isodose line, 5 fraction per week and a total dose of 40-51 Gy at PTV margin, 60-70 Gy at GTV margin and 80∼102 Gy at tumor centrical area was delivered in 2∼3 weeks. The median follow-up duration was 48 months. The complete response rate (CR) and the overall response rate (CR+PR) were 46.2% and 80.8%, respectively, after 2-3months of the treatments. The 1-, 2-, 3-, 4- and 5-year overall survival rates were 82.7%, 75.0%, 58.3%, 42.8%and 34.3%, respectively. The major treatment-related acute gastrointestinal toxicities included nausea or vomiting. The incidence of Grade I/II gastrointestinal toxicities was 19.2%. The acute hematologic toxicities were 21.2% in Grade I, 11.5% in Grade II and 1.9% in Grade III. None of all patients was observed with acute hepatic toxicities during the treatment . Late hepatic toxicities were 13.5% in Grade I/II and 3.8% in Grade III. The whole process was bearable for all patients after allopathy. The γ-ray stereotactic body radiation therapy(γ-ray SBRT) is effective and safe which fraction schema of 3-5 Gy/fraction, 5 days a week with a total dose of 45∼51 Gy at 50% isodose line was delivered for patients with early stage primary hepatic carcinomas. It can improve the local control rate and survival rate for patients with stage I/II.

A Novel Murine Femoral Segmental Critical-Sized Defect Model Stabilized by Plate Osteosynthesis for Bone Tissue Engineering Purposes

Mouse models are invaluable tools for mechanistic and efficacy studies of the healing process of large bone defects resulting in atrophic nonunions, a severe medical problem and a financial health-care-related burden. Models of atrophic nonunions are usually achieved by providing a highly stable biomechanical environment. For this purpose, external fixators have been investigated, but plate osteosynthesis, despite its high clinical relevance, has not yet been considered in mice. We hereby proposed and investigated the use of an internal osteosynthesis for stabilizing large bone defects. To this aim, a 3.5-mm-long segmental bone defect was induced in the mid-shaft of the femur using a Gigli saw and a jig. Bone fixation was performed using a titanium microlocking plate with four locking screws. The bone defect was either left empty or filled with a syngenic bone graft or filled with a coralline scaffold. Healing was monitored using radiographs. The healing process was further assessed using microcomputed tomography and histology 10 weeks after surgery. With the exception of one mouse that died during the surgical procedure, no complications were observed. A stable and reproducible bone fixation as well as a reproducible fixation of the implanted materials with full weight bearing was obtained in all animals tested. Nonunion was consistently observed in the group in which the defects were left empty. Bone union was obtained with the syngenic bone grafts, providing evidence that, although such defects were of critical size, bone healing was possible when the gold-standard material was used to fill the defect. Although new bone formation was greater in the coralline scaffold group than in the left-empty animal group, it remained limited and localized close to the bony edges, a consequence of the critical size of such bone defect. Our study established a reproducible, clinically relevant, femoral, atrophic nonunion, critical-sized defect, low morbidity mouse model. The present study was successful in designing and testing in a small animal model, a novel surgical method for the assessment of bone repair; this model has the potential to facilitate investigations of the molecular and cellular events involved in bone regeneration in load-bearing, segmental-bone defects.

Chemical alterations to murine brain tissue induced by formalin fixation: implications for biospectroscopic imaging and mapping studies of disease pathogenesis

Understanding biochemical mechanisms and changes associated with disease conditions and, therefore, development of improved clinical treatments, is relying increasingly on various biochemical mapping and imaging techniques on tissue sections. However, it is essential to be able to ascertain whether the sampling used provides the full biochemical information relevant to the disease and is free from artefacts. A multi-modal micro-spectroscopic approach, including FTIR imaging and PIXE elemental mapping, has been used to study the molecular and elemental profile within cryofixed and formalin-fixed murine brain tissue sections. The results provide strong evidence that amino acids, carbohydrates, lipids, phosphates, proteins and ions, such as Cl(-) and K(+), leach from tissue sections into the aqueous fixative medium during formalin fixation of the sections. Large changes in the concentrations and distributions of most of these components are also observed by washing in PBS even for short periods. The most likely source of the chemical species lost during fixation is the extra-cellular and intra-cellular fluid of tissues. The results highlight that, at best, analysis of formalin-fixed tissues gives only part of the complete biochemical "picture" of a tissue sample. Further, this investigation has highlighted that significant lipid peroxidation/oxidation may occur during formalin fixation and that the use of standard histological fixation reagents can result in significant and differential metal contamination of different regions of tissue sections. While a consistent and reproducible fixation method may be suitable for diagnostic purposes, the findings of this study strongly question the use of formalin fixation prior to spectroscopic studies of the molecular and elemental composition of biological samples, if the primary purpose is mechanistic studies of disease pathogenesis.

High-Quality Lung Fixation by Controlled Closed Loop Perfusion for Stereological Analysis in a Large Animal Model

Stereology is an essential method for quantitative analysis of lung structure. Adequate fixation is a prerequisite for stereological analysis to avoid bias in pulmonary tissue, dimensions and structural details. We present a technique for in situ fixation of large animal lungs for stereological analysis, based on closed loop perfusion fixation. Twenty anesthetized ventilated pigs (30 ± 3 kg) underwent cannulation of the pulmonary artery and ligation of the right hilus. Following circulatory arrest a continuous positive pressure of 12 mbar was applied to the airways and lung perfusion started with the fixative solution (1.5% paraformaldehyde; 1.5% glutaraldehyde in 0.15 M HEPES). In five animals, a single-pass perfusion technique was performed, in 15 subsequent animals, the closed-loop technique was applied. Afterwards, lungs were removed, externally postfixed in the recycled fixative solution, and stored at 4 °C. Fifteen lung specimens underwent stereological analysis with volume estimation and subsequent systematic uniform random sampling for light and electron microscopic analysis. Singlepass perfusion did not result in satisfactory fixation. Left lung closed loop perfusion rate was 0.5-0.7 L/min with total median [min-max] perfusion time of 15 min (11-19). Perfusion pressure was 15 mm Hg (9-33). Subsequent lung analysis revealed well-preserved cell and tissue ultrastructure. The closed loop perfusion technique represents a valuable and reproducible fixation method in large animal models. Pressure controlled fixation perfusion results in high-quality preservation of in situ parenchymal architecture of lungs with or without injury, which is ideally suited for quantitative assessment of lung structure by stereology.

Virtual Neck Exploration

Computed tomography (CT) together with 99mTc-sestamibi single photon emission computed tomography (MIBI-SPECT) image fusion (CT-MIBI-SPECT image fusion) allows virtual exploration of the neck. The aim of this study was to evaluate whether CT-MIBI-SPECT image fusion is superior to MIBI-SPECT and CT in detecting abnormal parathyroid glands in patients with primary hyperparathyroidism. CT-MIBI-SPECT image fusion for preoperative localization was performed in 116 patients with primary hyperparathyroidism (pHPT). Both investigations were performed with reproducible fixation of the patient on a vacuum mattress. At a special work station the neck was virtually explored by viewing the CT images in all 3 dimensions. The MIBI-SPECT images were superimposed on underlying CT images. Only patients with single-gland disease were evaluated (pHPT: 112, persistent pHPT: 1, recurrent pHPT: 1, persistent secondary hyperparathyroidism: 1, tertiary HPT after kidney transplantation: 1). CT-MIBI-SPECT image fusion results were compared with those obtained with CT alone and MIBI-SPECT alone. The predicted positions were correlated with the intraoperative findings. CT-MIBI-SPECT image fusion was able to predict the exact position of the abnormal gland in 102 (88%) of the 116 patients, whereas CT alone showed in 75 (65%) patients and MIBI-SPECT alone in 64 (55%) patients the exact position of the abnormal gland. Sixty-two patients underwent minimally invasive surgery, namely in 21 patients with a unilaterally focused approach and in 33 patients with a bilateral approach (27 of these underwent simultaneous thyroid resection). Sensitivity for CT-MIBI-SPECT image fusion was 88%, for CT alone 70%, and for MIBI-SPECT alone 59%. Specificity for CT-MIBI-SPECT image fusion was 99%, for MIBI-SPECT alone 95%, for CT alone 94%. Overall accuracy for CT-MIBI-SPECT image fusion was 97%, for CT alone 89%, for MIBI-SPECT 87%. This study provides evidence that CT-MIBI-SPECT image fusion is superior to CT or MIBI-SPECT alone for preoperative localization of enlarged parathyroid glands in patients with single-gland primary hyperparathyroidism.

Novel Fixation Technique for the Surgical Repair of Lung Hernias

We describe a novel technique for dealing with the rare complication of post-traumatic or post-thoracotomy lung herniation. The method uses techniques and fixation devices that have been developed for stabilization and fixation of the spine and surgical management of scoliosis. It allows for a secure, reliable, and easily reproducible fixation of the chest-wall in patients with large intercostal lung hernias using standard spinal instruments.

Salvage of C2 Pedicle and Pars Screws Using the Intralaminar Technique

Human cadaveric biomechanical analysis. The purpose of this study is to evaluate the ability of using 1 of the remaining 2 methods of instrumenting C2, should the initial method fail. Although 3 different methods of C2 fixation (pedicle, pars, and laminar screws) are possible, occasionally an attempt at screw insertion fails. In such cases, the surgeon needs a viable alternative to salvage/obtain fixation to obviate the need to instrument an additional motion segment. METHODS.: Eleven fresh-frozen cadaveric specimens (Occ-C4) were DEXA scanned for bone mineral density. On the left side, pedicle screws were first inserted, then pulled out. Then, "salvage" pars screws were inserted, then pulled-out, followed by laminar screws. On the right, a similar sequence was repeated, except that a pars screw was followed by a pedicle screw, then a laminar screw. All screws were placed by experienced cervical spine surgeons. Insertional torque (IT) was measured in Newton-meters (Nm). Tensile loading to failure was performed "in-line"with the screw axis at a rate of 0.25 mm/s using a MTS 858 MiniBionix II System with data recorded as peak pull-out strength (POS) in newtons "N". Pedicle screws generated statistically greater IT and POS than other techniques as the initial fixation type (P < 0.0001). Similar trends were observed with transpedicular fixation as a salvage procedure (P > 0.05). Laminar screws yielded consistently higher POS values than pars fixation when applied in a salvage scenario (POS range: LS = 146-707 N; PrS = 8-548 N); however, high standard deviation precluded statistical significance (P > 0.05). Significant predictive relationship was established between IT and POS for all screws using Pearson correlation coefficient and bivariate linear regression analysis (r = 0.75 and r = 0.511, respectively; P < 0.01). Our results suggest that pedicle screws provide the strongest fixation for both initial and salvage applications. If they should fail, lamina screws appear to provide stronger and more reproducible fixation than pars screws.

Is mask-based stereotactic head-and-neck fixation as precise as stereotactic head fixation for precision radiotherapy?

Background: The aim of this study was to compare setup accuracy and reproducibility of a stereotactic head and a head-and-neck fixation system, both based on thermoplastic material. Methods and Material: Ten patients were immobilized with a head and a head-and-neck fixation system (both BrainLAB, Germany). Both mask systems were modified with a custom-made mouthpiece and a strip of thermoplastic material attached to the lower part of the mask. During the first treatment session, after positioning patients using room lasers, two orthogonal portal images were taken as reference. Later on, at least five sets of orthogonal portal images were acquired for each patient. The isocentric setup accuracy was determined by comparing field edges and anatomic landmarks and the repositioning accuracy in the mask was obtained by comparing individual anatomic landmarks with respect to the metal balls, fixed on the masks. Systematic and random deviations and resulting three-dimensional (3D) vectors were calculated. Additionally, margins were derived from the systematic and random component of the isocentric setup accuracy. Finally, inter- and intraobserver variations were analyzed. Results: The systematic variation of the isocentric setup accuracy was very similar for the two mask systems, but the random variations were slightly larger for the head-and-neck system, resulting in a 0.4-mm larger 3D vector. The repositioning variations for the head mask were smaller compared with the head-and-neck mask, resulting in smaller 3D vectors for the random (∼0.4 mm) and systematic variations (∼0.6 mm). For both mask systems, a 2-mm margin can be used in lateral and anteroposterior direction, whereas in craniocaudal direction, this margin should be extended to 2.5 mm for the head mask and to 3 mm for the head-and-neck mask. The average absolute differences between two observers were within 0.5 mm, maximum deviations around 1 mm. Conclusion: Thermoplastic mask–based stereotactic head-and-neck fixation allows accurate and reproducible fixation of patients. For intensity-modulated radiation therapy in the upper head-and-neck region, the application of reduced margins around 2–3 mm, which has an implication on organ sparing, is enabled by such an immobilization device.

Enhanced CAS in head and neck-surgery: evaluation of intraoperative data modality iMRI and sonography

Purpose: Computer-assisted surgical procedures are well established in head/neck- and neurosurgery. Most systems are based on preoperative CT or MR data. To visualize the surgical change and re-registration, there is a need for intraoperative imaging. Currently, only few imaging methods are available to supply up-to-date information on the surgical progress, e.g., inter-/intraoperative MRI, interoperative CT, and sonography/ultrasound. The purpose of this study is to compare procedures and algorithms for intraoperative co-registration of iMRI and sonography in head/neck- and neurosurgery. Methods: Intraoperative imaging was performed by interventional MR (GE Signa SP) and high-resolution ultrasound (Siemens Sienna). iMRI: Localite Navigator Software (enhanced CAS) allows integration of preoperative data to intraoperative imaging of MR, fMR and CT. The co-registration was based on fiducial markers. The implementation was designed as a multimode real-time navigation system supplying images of bony structures/contours (derived from CT data) fused into real-time MR images. A total of 10 markers (three forehead, three temporal scalp, three mastoid, and one occipital scalp) were used in this study to define reproducible fixation points. Sonography: Based on neuronal networks, a recognize-algorithm for co-registration was developed using sonography data sets of the neck. Results: The statistical point-to-point accuracy (marker difference) of co-registration in the open MR was determined to be 1.2±0.1 mm. The co-registration CT preop and iMRI are reliable and nowadays established in selected surgical procedures of the skull base, e.g., biopsy of the petroclival region. The system yields a significantly better image quality and higher repetition rate than the standard real-time images. Typical for any marker-based registration, the matching accuracy for the registered data sets depends on the accuracy of locating the markers in the respective images, and the inherent displacement of the fiducial markers. The markerless co-registration Sono preop/Sono intraop based on neuronal networks is still less reliable with a positive recognition rate of 46/51 of structures with a maximal volume of 2.110 cm 3. Recognized structures can be used for co-registration with different data modalities, e.g., MR, CT or for single-modality navigation. Conclusions: Both interventional MRI as well as sonography allows intraoperative data update. The marker-based co-registration CT preop/iMRI is still more reliable than Sono preop/Sono intraop based on neuronal networks. Further developments tend towards the improvement of mutual information algorithm and marker-like landmarks to improve the recognition rate of integrated sonography. Low costs and less surgical tools expenditure are the advantages of sonography, and it will be a serious possibility for intraoperative CAS-update. Otherwise, the study demonstrates the possibility of combining intraoperative MR and sonography with other modalities for enhanced CAS in ORL and neurosurgery.

Radiotherapy of childhood brain stem tumours

STUDY OBJECTIVE: Description and evaluation of radiotherapy of inoperable brain stem tumours. Possibilities of improving therapeutic results. MATERIALS AND METHODS: Between 1987 and 2000 43 patients (23 boys and 20 girls, mean age 8.5+/-4.4 years) with brain stem tumours were treated with 6 MV and 9 MV X-ray. The doses administered ranged from 30 to 66 Gy; mean 50.41+/-7.67 Gy. Treatment in each case was performed according to CT- and /or MR-based radiotherapy plan. Since 2000 3D conformal radiotherapy plans have been prepared by using image fusion. RESULTS: All patients were followed. The mean follow-up period was 19.4 months (range: 1 to 112 months). For survival statistics the 2 to 3-year overall and symptom-free survivals were taken into account, the former ones in the function of tumour localisations. The gender of children did not affect the survival (p>0.74). No significant difference was found as to survival in the function of tumour localisation either (p>0.87). CONCLUSION: According to the literature data the results expected were not achieved by hyperfractionation and by delivering an overall focal dose of 72 to 78 Gy. Results can be improved by precise patient fixation and the routine application of 3D conformal radiotherapy plans prepared by CT- and MR-based image fusion. These together can result the correctly reproducible patient fixation, the homogenous radiation delivery in the target volume and the reduction of injury in the surrounding tissues. Irradiation should be performed also in histologically not verified tumours since a 24.6 month transitory improvement could be achieved in 60.5% of our patients.

New Fixation Technique for Preimplantation Genetics Diagnosis

Objectives: Current fixation techniques for preimplantation genetic diagnosis present an embryologist with several problems. These include premature drying, resulting in excess of cytoplasm; scattering which may lead to specimen loss; and significant variation in the required duration of treatment with pepsin. As a result, blastomeres or polar body fixation is a cumbersome and stressful process that requires extensive training. The development of an easier and more reproducible fixation technique is an important goal that was addressed in the present study.

The bone-vacuum cementing technique in total hip arthroplasty. A radiological study

The bone-vacuum cementing technique is a promising method developed to obtain a reliable and reproducible fixation of the femoral component. To date, there have been no clinical reports on the efficacy of this technique in attaining the immediate goals of providing a uniform cement mantle and an optimal position of the prosthesis. The purpose of the present investigation was to describe the radiological results of the bone-vacuum cementing technique for the fixation of the stem and to compare the outcomes with a contemporary technique.

Volumetric MRI measurements of the tree shrew hippocampus

Protocols suitable for repeated magnetic resonance imaging (MRI) studies of the tree shrew’s brain were established. This included the development of (i) a technique for prolonged inhalation anesthesia by endotracheal intubation; (ii) a reproducible fixation of the animal’s head in a stereotaxic frame and finally (iii) the set-up of the hardware (rf coil) and software (MRI sequences) of the MRI system. The endotracheal intubation as well as the repeated and prolonged anesthesia showed no complications. The in vivo measurements of the tree shrew’s hippocampal formation revealed a high reproducibility. Right and left hippocampal volume was determined as 85.2 mm 3±8% and 87.4 mm 3±10%, respectively. The utility of MRI in delineating alterations in brain anatomy was demonstrated in three animals receiving cortisol via the drinking water (5 mg/animal/day). After a 4-week treatment, in two of the three tree shrews a reduction in hippocampal volume was observed. Thus, the MRI protocols used here allow for repeated and non-invasive measurements of changes in hippocampal anatomy within the same animal and to monitor the temporal dynamics of structural alterations within this brain structure.

Calibration and Standardization of Microwave Ovens for Fixation of Brain and Peripheral Nerve Tissue

Rapid and reproducible fixation of brain and peripheral nerve tissue for light and electron microscopy studies can be done in a microwave oven. In this review we report a standardized nomenclature for diverse fixation techniques that use microwave heating: (1) microwave stabilization, (2) fast and ultrafast primary microwave–chemical fixation, (3) microwave irradiation followed by chemical fixation, (4) primary chemical fixation followed by microwave irradiation, and (5) microwave fixation used in various combinations with freeze fixation. All of these methods are well suited to fix brain tissue for light microscopy. Fast primary microwave–chemical fixation is best for immunoelectron microscopy studies. We also review how the physical characteristics of the microwave frequency and the dimensions of microwave oven cavities can compromise microwave fixation results. A microwave oven can be calibrated for fixation when the following parameters are standardized: irradiation time; water load volume, initial temperature, and placement within the oven; fixative composition, volume, and initial temperature; and specimen container shape and placement within the oven. Using two recently developed calibration tools, the neon bulb array and the agar–saline–Giemsa tissue phantom, we report a simple calibration protocol that identifies regions within a microwave oven for uniform microwave fixation.