Cortical Windows Research Articles

Cortical windows for implant and cement removal during revision total elbow arthroplasty

Cortical windows for implant and cement removal during revision total elbow arthroplasty

Quantitative Analysis of the Weakening Effect of Cortical Windows in Non-Osteoporotic and Osteoporotic Proximal Femurs

Quantitative Analysis of the Weakening Effect of Cortical Windows in Non-Osteoporotic and Osteoporotic Proximal Femurs

Wright's Technique with the Addition of Visualized Axial Cortical Windows in Odontoid Fractures.

This study sought to investigate and evaluate a modified axial translaminar screw fixation for treating odontoid fractures. We performed a retrospective study at Wenzhou Medical University Affiliated Second Hospital between March 2016 and June 2018. We retrospectively collected and analyzed the medical records of 23 cases with odontoid fractures. All patients were identified as type II odontoid fractures without neurological deficiency and serious diseases following the classification of Anderson. The average age, gender ratio, and body mass index (BMI) were 54.3 ± 11.1 years, 12 men to 11 women, and 22.6 ± 2.4 kg/m2, respectively. Patients in this study accepted screw fixation using our modified axial translaminar screw fixation combined with atlas pedicle or lateral mass screw fixation. Within the technique, a small cortical “window” was dug in the middle of the axial contralateral lamina, such that the screws in the lamina were visualized to prevent incorrectly implanting the posterior spinal canal through the visualized “window.” A total of 46 bone screws were accurately inserted into the axial lamina without using fluoroscopy. The length of all translaminar screws ranged between 26 and 30 mm, while the diameter was 3.5 mm. During the follow‐up survey, the visual analog scale (VAS) and neck disability index (NDI) were measured. We provide a simple modification of Wright's elegant technique with the addition of “visualized windows” at the middle of the axial lamina. In all patients, screws were inserted accurately without bony breach and the screw angle was 56.1 ± 3.0°. Mean operative time was 102 ± 28 min with an average blood loss of 50 ± 25 mL. Postoperative hemoglobin and mean length of hospital stay were 12.0 ± 1.4 g/dL and 10.4 ± 3.4 days, respectively. The average follow‐up time of all cases was 14.7 months and no internal fixation displacement, loosening, or breakage was found. All patients with odontoid fractures reported being satisfied with the treatment during the recheck period and good clinical outcomes were observed. At 1, 6, and 12 months, NDI and VAS showed that the symptoms of neck pain and limitations of functional disability improved significantly during follow‐up. Our results suggest that the modified translaminar screw fixation technique can efficiently treat Anderson type II odontoid fracture, followed by the benefits of less soft tissue dissection, simple operation, no fluoroscopy, and accurate placement of screws.

Intrinsic timescales across the basal ganglia

Recent studies have shown that temporal stability of the neuronal activity over time can be estimated by the structure of the spike-count autocorrelation of neuronal populations. This estimation, called the intrinsic timescale, has been computed for several cortical areas and can be used to propose a cortical hierarchy reflecting a scale of temporal receptive windows between areas. In this study, we performed an autocorrelation analysis on neuronal populations of three basal ganglia (BG) nuclei, including the striatum and the subthalamic nucleus (STN), the input structures of the BG, and the external globus pallidus (GPe). The analysis was performed during the baseline period of a motivational visuomotor task in which monkeys had to apply different amounts of force to receive different amounts of reward. We found that the striatum and the STN have longer intrinsic timescales than the GPe. Moreover, our results allow for the placement of these subcortical structures within the already-defined scale of cortical temporal receptive windows. Estimates of intrinsic timescales are important in adding further constraints in the development of computational models of the complex dynamics among these nuclei and throughout cortico-BG-thalamo-cortical loops.

Surgical Technique of a Cement-On-Cement Removal System for Hip and Knee Arthroplasty Revision Surgery

Cement removal during hip or knee arthroplasty revision surgery is technically demanding and prone to severe complications such as periprosthetic fractures, incomplete cement removal, or perforations. Several alternative techniques have been developed to enable complete, accurate, and safe removal of cement from bone, including osteotomies and cortical windows, endoscopic instruments, ultrasound devices, lithotripsy, and laser-assisted removal. We describe a cement-on-cement technique with a sterile, single-use tool for cement removal. The cement is removed piece by piece using a specifically designed device, without osteotomies or cortical windows.

Two-stage distalization of the mental foramen to manage posterior mandibular vertical bone deficiency—a prospective observational study

Inferior alveolar nerve (IAN) transpositioning is a modality utilized to manage posterior mandibular vertical deficiency. Several complications have been reported including improper implant positioning, mandibular body fracture, and neurosensory disturbance. The aim of this prospective observational study was to introduce a two-stage mental foramen distalization technique to minimize the complications associated with IAN transpositioning. Ten patients with severely atrophied mandibular ridges were included. Cone beam computed tomography was ordered to accurately locate the position of the IAN and its incisive terminal branch before designing the outline of two cortical osteotomies anterior and posterior to the mental foramen. The osteotomies were created using a piezoelectric device, followed by separation and identification of the nerve. The incisive branch was severed to freely transpose the IAN. A new foramen was created far distally and the cortical windows were repositioned and fixed with two screws. Healing was uneventful for all patients. Neurosensory recovery was assessed by MRC scale. All cases showed full recovery within 6 weeks, except for two patients who showed complete recovery after 16 weeks. Four months postoperative, all patients showed complete consolidation of the cortical windows without any signs of failure implants were placed at the pre-planned surgical sites. Histomorphometric analysis of core biopsies from seven surgical sites showed bone area percentages ranging from 46% to 63%. The two-stage mental foramen distalization technique is a predictable and safer technique for IAN transpositioning specifically in cases of vertical bone deficiency associated with limited inter-arch space.

Cortical Windows in Stereocaulon

Green algal photosynthetic units in the genus Stereocaulon (phyllocladia or areoles) are typically white to pale gray, but certain species develop a darker central portion. Structurally, these dark-centered areoles of crustose Stereocaulon are identical to the phyllocladia of the S. vesuvianum group. The dark-centered photosynthetic units may have an adaptive role, separating tissue for gas exchange from tissue for water uptake and light transmission. I hypothesize that the white portions of cortex on the photosynthetic units have reflective extracellular deposits that optically occlude the cortex but allow gas exchange through hydrophobic air channels. In contrast, the dark centers apparently provide transparent and water-transmissive windows into the algal layer through an otherwise relatively opaque cortex. Cortical windows are apparently unusual in lichens and may be an adaptation to provide gas exchange in cold, wet environments. For crustose species, the areoles often protrude from a thin film of water over rock and the dual cortex appears to provide both light transmission and gas exchange. Similarly, for the S. vesuvianum group, the dual cortex may provide light transmission and gas exchange for water-saturated thalli in oceanic environments.

The router bit extraction technique for removing a well-fixed humeral stem in revision shoulder arthroplasty.

A number of methods have been described to remove a well-fixed humeral implant as part of revision shoulder arthroplasty. These include the use of cortical windows and humeral osteotomies. The router bit extraction technique uses a high-speed router bit to disrupt the bone-implant interface. The implant is then struck in a retrograde fashion with a square-tip impactor and mallet. The purpose of this study was to determine the characteristics and frequency of the different techniques needed for the removal of a well-fixed humeral stem in revision shoulder arthroplasty. Between 2010 and 2018, 288 revision shoulder arthroplasty procedures requiring removal of a well-fixed humeral component were carried out at a tertiary referral centre by a single surgeon. The patient demographics, indications for surgery, and method of extraction were collected. Of the 288 revisions, 284 humeral stems (98.6%) were removed using the router bit extraction technique alone. Four humeral stems (1.39%) required an additional cortical window. Humeral osteotomy was not necessary in any procedure. Most of the humeral stems removed (78.8%) were cementless. Of the four humeral stems that required a cortical window, three involved removal of a hemiarthroplasty. Two were cemented and two were cementless. The router bit extraction technique removed a well-fixed humeral component in a very high proportion of patients (98.6%). This method allows surgeons to avoid more invasive approaches involving a cortical window or humeral osteotomy, and their associated complications. Cite this article: Bone Joint J 2019;101-B:1280-1284.

Intravital microscopy: Imaging host-parasite interactions in the brain.

Intravital fluorescence microscopy (IVM) is a powerful technique for imaging multiple organs, including the brain of living mice and rats. It enables the direct visualisation of cells in situ providing a real-life view of biological processes that in vitro systems cannot. In addition, to the technological advances in microscopy over the last decade, there have been supporting innovations in data storage and analytical packages that enable the visualisation and analysis of large data sets. Here, we review the advantages and limitations of techniques predominantly used for brain IVM, including thinned skull windows, open skull cortical windows, and a miniaturised optical system based on microendoscopic probes that can be inserted into deep tissues. Further, we explore the relevance of these techniques for the field of parasitology. Several protozoan infections are associated with neurological symptoms including Plasmodium spp., Toxoplasma spp., and Trypanosoma spp. IVM has led to crucial findings on these parasite species, which are discussed in detail in this review.

Early Results of the Medial Approach for Arthroscopic-Assisted Fixation of Lateral Tibial Plateau Fractures

The use of arthroscopy in the management of tibial plateau fractures is not a particularly new concept. It has been used successfully for Schatzker types I–III fractures. In addition to evaluating the fracture itself, it is easier to evaluate the other intraarticular structures. Coventionally, reduction for lateral tibial plateau fractures have been performed through a laterally based metaphyseal window, which is not without limitations, including difficulty with reduction of the fracture, as well as bone grafting though the resultant short subchondral tunnel. Also, there is a risk of lateral vascular supply distrubtion because of same side fracture. A medially based metaphyseal window to approach lateral tibial plateau fractures allows for minimal insult to the soft tissues, with advantageous ease of reduction and grafting through a longer tunnel for subchondral support. We aimed to present our initial experiences in twelwe cases approaching lateral tibial plateau fractures through a medial metaphyseal window.Material-Methods:Our series involves 12 patients with 7 Schatzker type II, 3 Schatzker type I, and 2 Schatzker type III fractures. There were 8 males and 4 females. The average age at the time of surgery was 37 (25-57) years. All of the patients underwent plain radiography and BT in each knee Time from injury to surgery was 6.2 days. Follow up was 18 months (9-22 months).Firstly diagnostic arthroscopy was performed. Concomittant pathology was adreessed as needed. There was 3 lateral meniscus tear that treated with partial meniscectomy. An ACL guide pin was placed percutaneously anteromedial tibia approximately 9 cm distal to the joint line. Once stisfactory positioning a cortical window 1x2 cm. made around the guide pin. Reduction was accomplished with a bone tamp that fits easily into the tunnel. Screws were used as rafters to support the articular surface and subchondral bone. We used in 7 patients lateral plate and screws and in 5 patients only screws. Care was taken to keep pump pressure at approximately 40 millimeters of mercury for alleviate the risk of compartment syndrome.Results:No complications related to the procedure were observed. No secondary loss of reduction was observed in radiological controls. Functional assessment according to HSS of the patients were excellent in 5 cases, good in 5 cases and fair 2 cases.Discussion:Because depressed fragments are elevated from distal cortical windows, the importance of an intact, or easily restored, “cortical envelope” is paramount. This case series showed satisfactory early clinical results.clinical picturepostop. x-ray

Humeral windows in revision total elbow arthroplasty.

The use of cortical windows for revision elbow arthroplasty has not previously been widely reported. Their use aids safe revision of a well fixed humeral prosthesis and can be used in the setting of dislocation, periprosthetic fracture or aseptic loosening of the ulnar component. We describe our technique and results of cortical windows in the distal humerus for revision elbow arthroplasty surgery.

A Novel Antero-Medial Cortical Window Technique for Removal of Well-Fixed Fully Porous Stem in Revision Total Hip Arthroplasty

Fully porous-coated cementless stem has the advantage of good initial metaphyseal to diaphysial fixation. However, it is very difficult to remove the stem when complications develop. Extraction of a stem may cause huge damage to the femur. A long stem may be required to ensure stability for subsequent femoral reconstruction. Here we present a case employing a novel technique of minimizing invasion to the femur when a wellfixed, extensively porous-coated cementless stem needs to be removed. A 58-year-old woman had a revision total hip arthroplasty for trunnionosis after the left total hip arthroplasty. In the operation we made two cortical windows to the femur. It enabled us to reach all circumferences of the stem. By this technique the stem could be easily removed and the femoral canal structure was preserved. The femur could then be reconstructed with a stem of normal length. The Anatomic Medullary Locking (AML) stem is a representative implant of a fully porous-coated cementless stem that brings out the problems of trunnionosis which leads to adverse reaction to metal debris and stem neck fracture. Revision total hip arthroplasty is on the increase because of these complications. It is considered that our technique is useful in such cases.

Nickel-Titanium Shape-Memory Sawtooth-Arm Embracing Clamp for Complex Femoral Revision Hip Arthroplasty

PurposesTo examine the clinical outcomes of patients treated with a nickel-titanium shape-memory sawtooth-arm embracing clamp (Ni-Ti SSEC) in complex femoral revision surgery. MethodsWe retrospectively evaluated the outcomes for 21 complex femoral revision hip arthroplasties that we treated using an Ni-Ti SSEC. The Ni-Ti SSEC was used for various procedures, including the fixation of extremely long cortical windows (11 patients), femoral shaft osteotomy (4 patients), an extended trochanteric osteotomy (3 patients), and protection of a penetrated femoral cortex by a primary stem (3 patients). All patients received follow-up care for an average of 48.2 months. ResultsThe mean time of Ni-Ti SSEC insertion intraoperatively was 6 minutes. The mean Harris Hip Score improved from 21.2 points before revision surgery to 83.1 points at the most recent examination. No implant failures or malunions occurred. Dislocation and deep infection occurred in 1 case during the follow-up period. ConclusionsOur results show that the embracing clamp is a simple and valid method for fixing osteotomies in treating complex femoral revision surgery.

The Medial Approach for Arthroscopic-Assisted Fixation of Lateral Tibial Plateau Fractures

Objectives:Tibial plateau fractures are complex injuries involving the weight bearing surface of the tibia. Open reduction and internal fixation with plates and screws is an established method of treatment for complex fractures (Schatzker types V–VI). Arthroscopically assisted techniques have been used successfully for simple fractures (Schatzker types I–III). Historically, arthroscopic-assisted reduction for lateral tibial plateau fractures have been performed through a laterally based metaphyseal window. We found this technique to have several limitations, including bone grafting through a short subchondral tunnel. Also, there was a risk of lateral vascular supply distrubtion. We proposed that medial window approach technique would provide a longer tunnel for subchondral support and aid in fracture reduction. We aimed to present our initial experiences in first seven cases approaching lateral tibial plateau fractures through a medial metaphyseal window.Methods:Our series involves 7 patients with 5 Schatzker type II and 2 Schatzker type III lateral tibial plateau fractures treated by a single surgeon, using a medial approach for the arthroscopic assisted fixation. There were 5 males and 2 females. The average age at the time of surgery was 34.2 years, (29-52). All of the patients underwent plain radiography and CT scanning in each knee Time from injury to surgery was 7.2 days (4-12 days). Length of follow up was 9 months (6-22 months). There was 2 lateral meniscus tear that treated with partial meniscectomy and 1 MCL injury that treated conservativeely. Surgery was performed in four steps. First step was diagnostic arthroscopy of the injured knee, , second step was reduction of the fracture using a sylindiric tube with fluoroscopic guidance, third step was the arthroscopic verification of the fracture reduction, and finally percutaneous osteosynthesis of the fracture.Care is taken to keep the flow to gravity or, if using a pressure controlled pump, to set the pressure at approximately 40 millimeters of mercury. This will help alleviate the risk of compartment syndrome. Compartment firmness should be continuously monitored throughout the procedure.Results:No complications related to the procedure were observed. All patients reported a relevant reduction in pain, were able to mobilize with full weight bearing in the average 12 weeks (9–15 weeks). No secondary loss of reduction was observed in radiological controls; No revision surgery was required. Functional assessment according to HSS (hospital for special surgery) of the patients were excellent in 5 cases, good in 2 cases.Conclusion:Because depressed fragments are elevated from distal cortical windows, the importance of an intact, or easily restored, “cortical envelope” is paramount. In most Schatzker Type II and III fractures, the cortical envelope is either intact or can easily be restored with a clamp. The main advantage of medial approach for these fracture patterns is the creation of a long tunnel for subchondral support, the ease of fracture reduction and saving the lateral vascular supply.

Thermal epiphysiodesis performed with radio frequency in a porcine model

Background and purpose — Current techniques for epiphysiodesis involve opening of cortical windows; use of staples, screws, and tension devices; and fusion with curettes or drills. Complications may have serious consequences. There is a need for a more reliable, precise, and less traumatic procedure that overcomes the known complications from existing techniques. We analyzed a new epiphysiodesis technique using radio-frequency ablation (RFA) in a porcine model.Methods — Six 35-kg and two 25-kg immature pigs were used. 1 hind leg of each animal was randomly selected and the proximal tibia growth plate was ablated laterally and medially. The contralateral leg was used as a control. MR images were obtained immediately after the ablation and 12 weeks later for 6 animals, and 24 weeks later for the other 2 animals. CT was done for the 2 animals that were followed for 24 weeks for proof of bone bridges.Results — Both tibias were equal in length initially. At the 12-week follow-up, there was an average leg length discrepancy of 3.9 mm (95% CI: 3.0–4.8), and at 24 weeks the difference was 8.4 mm and 7.5 mm. No damage to the adjacent tissue was found. Bone bridges and physeal closure were found after 24 weeks. The pigs showed no discomfort after the intervention.Interpretation — We found RFA to be feasible for epiphysiodesis in a pig model. The method is minimally invasive and recovery may be quick compared to conventional methods. We recommend that the method should be tested in larger-scale safety studies before clinical application.

Risk of periprosthetic femur fracture after anterior cortical bone windowing

Background and purpose Removal of distal cement at femoral implant revision is technically challenging and is associated with complications such as cortical perforations. A technique that can reduce the risks and operating time is to make a small cortical window in the distal femur for enhanced access. We wanted to determine whether the use of long, bridging, cemented femoral stems is necessary to reduce the risk of postoperative periprosthetic fractures after using an anterior cortical bone window.Methods 66 fresh pig femurs underwent mechanical testing. Steel rods were implanted at 3 locations: (1) at the distal window edge, (2) 15 mm proximally to the cortical window edge, and (3) 15 mm distally. 54 femurs were tested using a 3-point bending setup and 12 femurs were tested using a torsional load setup.Results Load to fracture ratio and bending stiffness ratio were similar in the 3 groups, for either the 3-point bending test or the torsional load test.Interpretation Our findings suggest that bypass of cortical windows with a revision femoral component may not reduce the risk of periprosthetic fracture.

Timing-dependent effects of whisker trimming in thalamocortical slices including the mouse barrel cortex

Whisker trimming produces depression of cortical responses in the barrel cortex. However, it is unclear how the developmental timing modifies the effects of whisker trimming. We investigated cortical responses in thalamocortical slices that included the mouse barrel cortex using flavoprotein fluorescence imaging. A topological relationship was observed between the thalamic stimulated sites and cortical areas showing fluorescence changes. By adjusting the position of the thalamic stimulated sites and the cortical windows in which amplitudes of the fluorescence changes were measured, we succeeded to reduce the variability of cortical responses between slices. We then investigated the effects of whisker trimming in the thalamocortical slices. Whisker trimming from 4weeks to 8weeks (at 4–8weeks) of age significantly reduced cortical responses at 8weeks. However, whisker trimming started before 4weeks produced only slight depression or no significant effect on the thalamocortical responses. As sensory deprivation during a critical developmental period is known to prevent elimination of synapses, the presence of aberrant synapses may compensate the cortical depression induced by whisker trimming started before 4weeks. To test this possibility, whisker trimming performed at 0–6 or 0–7weeks of age was followed by regrowth of whiskers for 1–2weeks. Clear and significant potentiation of cortical responses was observed in these mice at 8weeks when compared with those of naive mice of the same age. Overall, these data suggest that whisker trimming, producing depression of thalamocortical responses, prevents elimination of aberrant synapses during a critical developmental period before 4weeks in the mouse barrel cortex.

Cortical windowing of the femoral diaphysis for cement/plug removal in hip revision surgery

To analyze the results of cortical windowing of the femoral diaphysis for well-fixed cement/plug removal during hip revision surgery. From May 2005 to June 2009, 14 patients (14 hips) were undergone revision total hip arthroplasty (THA), window was cut into the cortex of the femur, and the well-fixed cement/plug distal to the window was removed under the direct vision. After reimplanted the cementless revision stem, the cortical lids were replanted and fixed with 2 to 3 cerclage wires. Six patients who had suffered from osteoporosis were undergone morselized bone graft to the osteotomy site. Postoperatively, the patients were maintained at partial weight-bearing (touchdown) for 6 weeks and then advanced as they were able. The length of the cortical windows varied from 2.5 to 6.0 cm (mean, 3.4 cm), the width ranged from 0.8 to 1.4 cm (mean, 1.2 cm). In one patient the window was enlarged during the procedure to facilitate the cement/plug removal. The mean radiologically healing time for the windows was 19 weeks. There was no intraoperative femoral perforation during cement/plug removal. One femoral fracture during the revision stem was implanted. No postoperative periprosthetic fracture and other complications such as infection, implant subsidence occurred during the fellow-up. There was no femoral thigh pain or implant loosening with femoral window. The cortical windowing technique is very helpful to facilitate the well-fixed cement/plug distal to the prosthesis tip removal and the windows heal rapidly and decrease the femoral complications associated with revision THA.

Treatment of a Well-Fixed Modular Fully Porous Coated Stem After Fracture Using a Custom Rescue Sleeve

We report a novel technique for the treatment of a fractured fully porous-coated modular stem. The fracture of the stem occurred at the taper of the stem-body junction. In both cases, the stem was well-fixed distally making the reconstruction difficult. Previously, authors have reported the use of an extended trochanteric osteotomy or multiple cortical windows for removal of this type of prosthesis. The technique we describe uses a custom-made “rescue sleeve” that takes advantage of the distal ingrowth. The rescue sleeve is fitted onto the existing stem obviating the need for an extended trochanteric osteotomy. The rescue sleeve's geometry makes up for the loss in height and accepts the modular body components to give the surgeon the length options to optimize stability.

Joint capsule mast cells and neuropeptides are increased within four weeks of injury and remain elevated in chronic stages of posttraumatic contractures

The purpose of this article was to determine mast cell and neuropeptide nerve fiber numbers in joint capsules in posttraumatic contractures, as elevated numbers have been implicated in other fibrotic and contracture conditions. Twelve skeletally mature rabbits had intraarticular cortical windows removed from the medial and lateral femoral condyles and the knee joint immobilized. The contralateral unoperated limb served as a control. Equal numbers of rabbits were sacrificed 4 weeks after surgery or 40 weeks after the first surgery that included 32 weeks of remobilization. Six patients with chronic posttraumatic elbow joint contractures and six age-matched organ donor controls free of elbow contractures were also studied. Joint capsule myofibroblast, mast cell, and neuropeptide containing nerve fiber numbers were assessed with immunohistochemistry. The numbers of myofibroblasts, mast cells, and neuropeptide containing nerve fibers expressed as a percentage of total cells were significantly greater in the contracture capsules when compared to the control capsules at all time points (p < 0.0001). The range of percentages for the three components in the contracture capsules versus the controls were 41-48% versus 9-10%, 44-50% versus 11-13%, and 45-50% versus 10-12% for the acute and chronic stages of the rabbit model and the chronic stages in the human elbows, respectively. These data support the hypothesis that a myofibroblast-mast cell-neuropeptide fibrosis axis may underlie some of the pathologic changes in the joint capsule in posttraumatic contractures. Approaches designed to manipulate this axis, such as preventing degranulation of mast cells, warrant further investigation.