A rare posterior mediastinal mass: chordoma.

A 72-year-old female presented with 2 years of pro-gradient pain in the upper thoracic spine radiating to the left arm and leg. MRI revealed a 2.7 × 2.0 × 12 cm paravertebral mass at T2/T3, extending into the foraminal and epidural nerves with extensive dural sac contact in the left hemithorax. The removed tumour was surprisingly soft for a schwannoma or chordoma. However, after the surgery, histopathology revealed the presence of brachyury protein (T-box transcription factor T), which is characteristic of a chordoma. While chordomas are extremely rare, it is important that they are kept in mind for the differential diagnosis of a posterior mediastinal mass. Successful treatment can only be achieved through a complete en bloc resection. This can often be complex due to their location along the spine. This case report aims to highlight the features and treatment of this rare disease.

Impact of Structural Compliance of a Six Degree of Freedom Joint Simulator on Virtual Ligament Force Calculation in Total Knee Endoprosthesis Testing.

The AMTI VIVO™ six degree of freedom joint simulator allows reproducible preclinical testing of joint endoprostheses under specific kinematic and loading conditions. When testing total knee endoprosthesis, the articulating femoral and tibial components are each mounted on an actuator with two and four degrees of freedom, respectively. To approximate realistic physiological conditions with respect to soft tissues, the joint simulator features an integrated virtual ligament model that calculates the restoring forces of the ligament apparatus to be applied by the actuators. During joint motion, the locations of the ligament insertion points are calculated depending on both actuators' coordinates. In the present study, we demonstrate that unintended elastic deformations of the actuators due to the specifically high contact forces in the artificial knee joint have a considerable impact on the calculated ligament forces. This study aims to investigate the effect of this structural compliance on experimental results. While the built-in algorithm for calculating the ligament forces cannot be altered by the user, a reduction of the ligament force deviations due to the elastic deformations could be achieved by preloading the articulating implant components in the reference configuration. As a proof of concept, a knee flexion motion with varying ligament conditions was simulated on the VIVO simulator and compared to data derived from a musculoskeletal multibody model of a total knee endoprosthesis.

iCT Navigation for Transpedicular Screw Fixation in the Thoracolumbar Spine: Experience in 100 Consecutive Cases.

Background: Various guidance techniques have been developed for optimal pedicle screw placement. We present our initial experience with intraoperative CT (iCT) navigation for transpedicular screw fixation in the thoracolumbar spine. Objective: This study aimed to describe the accuracy and reliability of iCT navigation for transpedicular screw fixation. Material and Methods: One hundred consecutive patients underwent thoracolumbar pedicle screw fixation under iCT navigation. After iCT registration of the local bony anatomy with a firmly attached spinous process tracker, pedicle screw placement was performed under navigation with an infrared camera and infrared reflectors on insertion instruments. Screw trajectories of the intraoperative verification CT were matched against the navigation paths. Radiological and clinical follow-up was prospectively documented and retrospectively analyzed. The study included 47 women and 53 men with a mean age of 66 years. Indications for thoracolumbar pedicle fixation were degenerative instability with stenosis, cyst or disc herniation (82), spondylolytic instability (9), scoliosis with stenosis (6), and traumatic fractures (3). A total of 443 pedicle screws were inserted: 22 in the thoracic spine, 371 in the lumbar spine, and 50 in S1. Results and Conclusions: Four hundred thirty-five out of 443 screws (98%) were correctly placed. Misplacement was explained by loosened infrared reflectors on pedicle awl or probe, or by the displacement of the spinous process tracker; misplaced screws were re-inserted intraoperatively and showed correct placement on the second verification CT. Based on our first 100 cases, iCT navigation for transpedicular screw fixation in the thoracolumbar spine seems to be very accurate and reliable.

Incidence and Outcome of Aneurysmal Subarachnoid Hemorrhage: The Swiss Study on Subarachnoid Hemorrhage (Swiss SOS).

BACKGROUND AND PURPOSE: The purpose of this study was to assess nationwide incidence and outcomes of aneurysmal subarachnoid hemorrhage (aSAH). The Swiss SOS (Swiss Study on Subarachnoid Hemorrhage) was established in 2008 and offers the unique opportunity to provide this data from the point of care on a nationwide level. METHODS: All patients with confirmed aneurysmal subarachnoid hemorrhage admitted between January 1, 2009 and December 31, 2014, within Switzerland were recorded in a prospective registry. Incidence rates were calculated based on time-matched population data. Admission parameters and outcomes at discharge and at 1 year were recorded. RESULTS: We recorded data of 1787 consecutive patients. The incidence of aneurysmal subarachnoid hemorrhage in Switzerland was 3.7 per 100 000 persons/y. The number of female patients was 1170 (65.5%). With a follow-up rate of 91.3% at 1 year, 1042 patients (58.8%) led an independent life according to the modified Rankin Scale (0-2). About 1 in 10 patients survived in a dependent state (modified Rankin Scale, 3-5; n=185; 10.4%). Case fatality was 20.1% (n=356) at discharge and 22.1% (n=391) after 1 year. CONCLUSIONS: The current incidence of aneurysmal subarachnoid hemorrhage in Switzerland is lower than expected and an indication of a global trend toward decreasing admissions for ruptured intracranial aneurysms. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT03245866.

Neuro-musculoskeletal flexible multibody simulation yields a framework for efficient bone failure risk assessment.

Fragility fractures are a major socioeconomic problem. A non-invasive, computationally-efficient method for the identification of fracture risk scenarios under the representation of neuro-musculoskeletal dynamics does not exist. We introduce a computational workflow that integrates modally-reduced, quantitative CT-based finite-element models into neuro-musculoskeletal flexible multibody simulation (NfMBS) for early bone fracture risk assessment. Our workflow quantifies the bone strength via the osteogenic stresses and strains that arise due to the physiological-like loading of the bone under the representation of patient-specific neuro-musculoskeletal dynamics. This allows for non-invasive, computationally-efficient dynamic analysis over the enormous parameter space of fracture risk scenarios, while requiring only sparse clinical data. Experimental validation on a fresh human femur specimen together with femur strength computations that were consistent with literature findings provide confidence in the workflow: The simulation of an entire squat took only 38 s CPU-time. Owing to the loss (16% cortical, 33% trabecular) of bone mineral density (BMD), the strain measure that is associated with bone fracture increased by 31.4%; and yielded an elevated risk of a femoral hip fracture. Our novel workflow could offer clinicians with decision-making guidance by enabling the first combined in-silico analysis tool using NfMBS and BMD measurements for optimized bone fracture risk assessment.

Force Closure Mechanism Modeling for Musculoskeletal Multibody Simulation.

OBJECTIVE: Neuro-musculoskeletal multibody simulation (NMBS) seeks to optimize decision-making for patients with neuro-musculoskeletal disorders. In clinical practice, however, the inter-subject variability and the inaccessibility for experimental testing impede the reliable model identification. These limitations motivate the novel modeling approach termed as force closure mechanism modeling (FCM2). METHODS: FCM 2 expresses the dynamics between mutually articulating joint partners with respect to instantaneous screw axes (ISA) automatically reconstructed from their relative velocity state. Thereby, FCM2 reduces arbitrary open-chain multibody topologies to force closure n-link pendulums. Within a computational validation study on the human knee joint with implemented contact surfaces, we examine FCM2 as an underlying inverse dynamic model for computed muscle control. We evaluate predicted tibiofemoral joint quantities, i.e., kinematics and contact forces along with muscle moment arms, during muscle-induced knee motion against the classic hinge joint model and experimental studies. RESULTS: Our NMBS study provided the proof-of-principle of the novel modeling approach. FCM2 freed us from assuming a certain joint formulation while correctly predicting the joint dynamics in agreement with the established methods. Although experimental results were closely predicted, owing to noise in the ISA estimation, muscle moment arms were overestimated (RISA = 0.84 < RHINGE = 0.97, RMSEISA = 13.18 mm > RMSEHINGE = 6.54 mm), identifying the robust ISA estimation as key to FCM2. CONCLUSION: FCM2 automatically derives the equations of motion in closed form. Moreover, it captures subject-specific joint function and, thereby, minimizes modeling and parameterization efforts. SIGNIFICANCE: Model derivation becomes driven by quantitative data available in clinical settings so that FCM2 yields a promising framework toward subject-specific NMBS.

Dynamical analysis of dislocation-associated factors in total hip replacements by hardware-in-the-loop simulation.

Since dislocation of total hip replacements (THR) remains a clinical problem, its mechanisms are still in the focus of research. Previous studies ignored the impact of soft tissue structures and dynamic processes or relied on simplified joint contact mechanics, thus, hindered a thorough understanding. Therefore, the purpose of the present study was to use hardware-in-the-loop (HiL) simulation to analyze systematically the impact of varying implant positions and designs as well as gluteal and posterior muscle function on THR instability under physiological-like loading conditions during dynamic movements. A musculoskeletal multibody model emulated the in situ environment of the lower extremity during deep sit-to-stand with femoral adduction maneuver while a six-axis robot moved and loaded a THR accordingly to feed physical measurements back to the multibody model. Commercial THRs with hard-soft bearings were used in the simulation with three different head diameters (28, 36, 44 mm) and two offsets (M, XL). Cup inclination of 45°, cup anteversion of 20°, and stem anteversion of 10° revealed to be outstandingly robust against any instability-related parameter variation. For the flexion motion, higher combined anteversion angles of cup and stem seemed generally favorable. Total hip instability was either deferred or even avoided even in the presence of higher cup inclination. Larger head diameters (>36 mm) and femoral head offsets (8 mm) deferred occurrence of prosthetic and bone impingement associated with increasing resisting torques. In summary, implant positioning had a much higher impact on total hip stability than gluteal insufficiency and impaired muscle function. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2557-2566, 2017.

Impact of the patella height on the strain pattern of the medial patellofemoral ligament after reconstruction: a computer model-based study.

PURPOSE: Medial patellofemoral ligament (MPFL) reconstruction is a key procedure for treating patellofemoral instability. However, controversy exists regarding the correct graft placement in different patellar heights. Therefore, our study aimed to investigate the influence of patellar height on MPFL insertion points. METHODS: Strain patterns of the reconstructed MPFL were calculated using a dynamic musculoskeletal multibody simulation. Numerous patellar (proximal, central, distal) and femoral attachment sites (around the radiological point according to Schöttle) were analysed in the presence of different patella heights [Insall-Salvati (IS) indices 0.74, 1.0, 1.5] during dynamic knee flexion from 0° to 120°. RESULTS: The reconstructed MPFL showed an almost isometric behaviour at the anatomic insertion (IS 1.0). Slight variation (<5 mm) around the ideal femoral insertion point resulted in only small changes in MPFL tension. However, a displacement of 10 mm led to a significant increase in MPFL tension, especially in the more anteriorly/proximally located femoral attachment points. Depending on the patella height, there exists an area of absolute isometry of the MPFL (length change <3 %) on the femoral condyle, which did not necessarily coincide exactly with the radiological point, but was located within a radius of 5 mm around it. CONCLUSIONS: When reconstructed in the radiological femoral insertion point, MPFL strain patterns were only slightly affected by different patella heights (IS 0.74-1.5) suggesting that MPFL reconstruction could be safely performed using the radiological insertion. However, in case of a patella alta (IS 1.5), a slightly more proximal femoral insertion is beneficial for the biomechanical behaviour of the reconstructed MPFL.

The influence of intraoperative resection control modalities on survival following gross total resection of glioblastoma.

The purpose of the present study is to analyze the impact of intraoperative resection control modalities on overall survival (OS) and progression-free survival (PFS) following gross total resection (GTR) of glioblastoma. We analyzed data of 76 glioblastoma patients (30f, mean age 57.4 ± 11.6 years) operated at our institution between 2009 and 2012. Patients were only included if GTR was achieved as judged by early postoperative high-field MRI. Intraoperative technical resection control modalities comprised intraoperative ultrasound (ioUS, n = 48), intraoperative low-field MRI (ioMRI, n = 22), and a control group without either modality (n = 11). The primary endpoint of our study was OS, and the secondary endpoint was PFS-both analyzed in Kaplan-Meier plots and Cox proportional hazards models. Median OS in all 76 glioblastoma patients after GTR was 20.4 months (95 % confidence interval (CI) 18.5-29.0)-median OS in patients where GTR was achieved using ioUS was prolonged (21.9 months) compared to those without ioUS usage (18.8 months). A multiple Cox model adjusting for age, preop Karnofsky performance status, tumor volume, and the use of 5-aminolevulinic acid showed a beneficial effect of ioUS use, and the estimated hazard ratio was 0.63 (95 % CI 0.31-1.2, p = 0.18) in favor of ioUS, however not reaching statistical significance. A similar effect was found for PFS (hazard ratio 0.59, p = 0.072). GTR of glioblastoma performed with ioUS guidance was associated with prolonged OS and PFS. IoUS should be compared to other resection control devices in larger patient cohorts.

A Novel Approach for Dynamic Testing of Total Hip Dislocation under Physiological Conditions.

Constant high rates of dislocation-related complications of total hip replacements (THRs) show that contributing factors like implant position and design, soft tissue condition and dynamics of physiological motions have not yet been fully understood. As in vivo measurements of excessive motions are not possible due to ethical objections, a comprehensive approach is proposed which is capable of testing THR stability under dynamic, reproducible and physiological conditions. The approach is based on a hardware-in-the-loop (HiL) simulation where a robotic physical setup interacts with a computational musculoskeletal model based on inverse dynamics. A major objective of this work was the validation of the HiL test system against in vivo data derived from patients with instrumented THRs. Moreover, the impact of certain test conditions, such as joint lubrication, implant position, load level in terms of body mass and removal of muscle structures, was evaluated within several HiL simulations. The outcomes for a normal sitting down and standing up maneuver revealed good agreement in trend and magnitude compared with in vivo measured hip joint forces. For a deep maneuver with femoral adduction, lubrication was shown to cause less friction torques than under dry conditions. Similarly, it could be demonstrated that less cup anteversion and inclination lead to earlier impingement in flexion motion including pelvic tilt for selected combinations of cup and stem positions. Reducing body mass did not influence impingement-free range of motion and dislocation behavior; however, higher resisting torques were observed under higher loads. Muscle removal emulating a posterior surgical approach indicated alterations in THR loading and the instability process in contrast to a reference case with intact musculature. Based on the presented data, it can be concluded that the HiL test system is able to reproduce comparable joint dynamics as present in THR patients.

The Effect of Epidural Steroid Injection on Postoperative Outcome in Patients From the Lumbar Spinal Stenosis Outcome Study.

STUDY DESIGN: Retrospective analysis of data from patients participating in the Lumbar Spinal Stenosis Outcome Study (LSOS). OBJECTIVE: The aim of LSOS was to assess clinical outcomes after surgical or nonoperative treatment in patients with and without prior epidural steroid injections. SUMMARY OF BACKGROUND DATA: Epidural steroid injections (ESI), a common treatment modality, reduce symptoms in the short-term, but according to a subgroup analysis from the Spine Patient Outcomes Research Trial (SPORT) they reduce the amount of improvement after subsequent surgical or nonoperative treatment. METHODS: The data of 281 patients with lumbar spinal stenosis who had completed baseline and 6-month follow-up assessments were analyzed. Patients completed the Spinal Stenosis Measure (SSM). Changes in the SSM scores from baseline to follow-up were compared between patients with and without prior ESI, for the surgical and nonsurgical treatment groups. RESULTS: The mean (SD) age of the patients was 75 (8.7) years. 229 patients underwent surgery and 111 of these had received an ESI in the 12 months before surgery. Of the 52 patients treated nonoperatively, 29 had received a prior ESI. The unadjusted changes (improvement) in the SSM-symptom scores between baseline and 6 months' follow up were: surgery and prior ESI 0.95, surgery and no prior ESI 0.78 (P = 0.15); no surgery and prior ESI 0.28, no surgery and no prior ESI 0.29 (P = 0.85). When adjusted for confounding factors, the reduction in SSM-symptom score was greater for surgery than for nonoperative treatment by 0.41 points (P < 0.001); the effect of having had an ESI prior to study entry was -0.08 (P = 0.40). CONCLUSION: The analysis of outcomes in the LSOS cohort provided no evidence that ESIs have a negative effect on the short-term outcome of surgery or nonoperative treatment in patients with lumbar spinal stenosis. LEVEL OF EVIDENCE: 3.

Efficacy of Surgery and Further Treatment of Progressive Glioblastoma.

BACKGROUND: Treatment options for patients with glioblastoma at progression have remained controversial, and selection criteria for the appropriate type of intervention remain poorly defined. The objectives were to determine which factors favor the decision for second surgery and which factors are associated with overall survival (OS) and to evaluate the National Institutes of Health (NIH) recurrent glioblastoma scale. The scale includes tumor involvement of eloquent brain regions, functional status, and tumor volume. METHODS: A retrospective single-center analysis of patients with newly diagnosed glioblastoma undergoing initial surgery between January 2007 and December 2011 was performed. Patients were separated into two groups: those with versus those without second resection surgery at disease progression. OS was compared using the multiple logistic regression model, Cox proportional hazard regression, and Kaplan-Meier survival analysis. RESULTS: The data of 98 patients were statistically analyzed. Among the patients, 58 had initial surgery only (age 61.27 years; median OS [mOS] 14.81 months) and 40 underwent second surgery at disease progression (age 55 years; mOS 18.86 months). Age was the only predictor for repeated surgery (P = 0.012; odds ratio 0.94). At the time of tumor progression, administration of alkylating chemotherapy (P = 0.004; hazard ratio [HR] 0.24) or bevacizumab (P = 0.001; HR 0.23) was associated with longer OS. Reoperation was associated with a lower HR (P = 0.134; HR 0.66). The NIH recurrent glioblastoma scale showed statistically significant improvement of prognosis prediction with the addition of age. CONCLUSIONS: Surgery of progressive glioblastoma and postoperative treatment at the time of progression is associated with improved OS in some patients. The addition of age may improve survival prediction of the NIH recurrent glioblastoma scale.

Clinical outcome in lumbar decompression surgery for spinal canal stenosis in the aged population: a prospective Swiss multicenter cohort study.

STUDY DESIGN: This is a prospective, multicenter cohort study including 8 medical centers in the metropolitan area of the Canton Zurich, Switzerland. OBJECTIVES: To examine whether outcome and quality of life might improve after decompression surgery for degenerative lumbar spinal stenosis (DLSS) even in patients older than 80 years and to compare data with a younger patient population from our own patient collective. SUMMARY AND BACKGROUND DATA: Lumbar decompression surgery without fusion has been shown to improve quality of life in lumbar spinal canal stenosis. In the population older than 80 years, treatment recommendations for DLSS show conflicting results. METHODS: Eight centers in the metropolitan area of Zurich, Switzerland agreed on the classification of DLSS, surgical principles, and follow-up protocols. Patients were followed from baseline, at 6 months, and 12 months. Baseline characteristics were analyzed with 5 different questionnaires "Spinal Stenosis Measure, Feeling Thermometer, Numeric Rating Scale, 5D-3L, and Roland and Morris Disability Questionnaire." In addition, our study population was compared with a younger control group. Furthermore, we calculated the minimal clinically important differences. RESULTS: Thirty-seven patients with an average age of 82.5 ± 2.5 years reached the 12-month follow-up. Spinal Stenosis Measure scores, the Feeling Thermometer, the Numeric Rating Scale, and the Roland and Morris Disability Questionnaire showed significant improvements at the 6-month and 12-month follow-ups (P < 0.001). One EQ-5D-3Lsubgroup "anxiety/depression" showed no significant improvement (P = 0.109) at 12-month follow-up. The minimal clinically important difference for the "Symptom Severity scale" in the Spinal Stenosis Measure was achieved with improvement of 70% in the older patient population. CONCLUSION: Patients 80 years or older can expect a clinically meaningful improvement after lumbar decompression for symptomatic DLSS. Our patient population showed significant positive development in quality of life in the short- and long-term follow-ups. LEVEL OF EVIDENCE: 3.

Intracranial aneurysm rupture is predicted by measures of solar activity.

OBJECTIVE: The cause precipitating intracranial aneurysm rupture remains unknown in many cases. It has been observed that aneurysm ruptures are clustered in time, but the trigger mechanism remains obscure. Because solar activity has been associated with cardiovascular mortality and morbidity, we decided to study its association to aneurysm rupture in the Swiss population. METHODS: Patient data were extracted from the Swiss SOS database, at time of analysis covering 918 consecutive patients with angiography-proven aneurysmal subarachnoid hemorrhage treated at 7 Swiss neurovascular centers between January 1, 2009, and December 31, 2011. The daily rupture frequency (RF) was correlated to the absolute amount and the change in various parameters of interest representing continuous measurements of solar activity (radioflux [F10.7 index], solar proton flux, solar flare occurrence, planetary K-index/planetary A-index, Space Environment Services Center [SESC] sunspot number and sunspot area) using Poisson regression analysis. RESULTS: During the period of interest, there were 517 days without recorded aneurysm rupture. There were 398, 139, 27, 12, 1, and 1 days with 1, 2, 3, 4, 5, and 6 ruptures per day. Poisson regression analysis demonstrated a significant correlation of F10.7 index and RF (incidence rate ratio [IRR] = 1.006303; standard error (SE) 0.0013201; 95% confidence interval (CI) 1.003719-1.008894; P < 0.001), according to which every 1-unit increase of the F10.7 index increased the count for an aneurysm to rupture by 0.63%. A likewise statistically significant relationship of both the SESC sunspot number (IRR 1.003413; SE 0.0007913; 95% CI 1.001864-1.004965; P < 0.001) and the sunspot area (IRR 1.000419; SE 0.0000866; 95% CI 1.000249-1.000589; P < 0.001) emerged. All other variables analyzed showed no significant correlation with RF. CONCLUSIONS: We found greater radioflux, SESC sunspot number, and sunspot area to be associated with an increased count of aneurysm rupture. The clinical meaningfulness of this statistical association must be interpreted carefully and future studies are warranted to rule out a type-1 error.

Diffusion tensor imaging for anatomical localization of cranial nerves and cranial nerve nuclei in pontine lesions: initial experiences with 3T-MRI.

With continuous refinement of neurosurgical techniques and higher resolution in neuroimaging, the management of pontine lesions is constantly improving. Among pontine structures with vital functions that are at risk of being damaged by surgical manipulation, cranial nerves (CN) and cranial nerve nuclei (CNN) such as CN V, VI, and VII are critical. Pre-operative localization of the intrapontine course of CN and CNN should be beneficial for surgical outcomes. Our objective was to accurately localize CN and CNN in patients with intra-axial lesions in the pons using diffusion tensor imaging (DTI) and estimate its input in surgical planning for avoiding unintended loss of their function during surgery. DTI of the pons obtained pre-operatively on a 3Tesla MR scanner was analyzed prospectively for the accurate localization of CN and CNN V, VI and VII in seven patients with intra-axial lesions in the pons. Anatomical sections in the pons were used to estimate abnormalities on color-coded fractional anisotropy maps. Imaging abnormalities were correlated with CN symptoms before and after surgery. The course of CN and the area of CNN were identified using DTI pre- and post-operatively. Clinical associations between post-operative improvements and the corresponding CN area of the pons were demonstrated. Our results suggest that pre- and post-operative DTI allows identification of key anatomical structures in the pons and enables estimation of their involvement by pathology. It may predict clinical outcome and help us to better understand the involvement of the intrinsic anatomy by pathological processes.

Self-centering dual-mobility total hip systems: Prediction of relative movements and realignment of different intermediate components.

The increased jump distance against dislocation and the large range of motion due to the enlarged effective head diameter substantiate the use of dual-mobility systems in cases of total hip joint instability. For this type of total hip endoprostheses, an eccentric design of the outer bearing is assumed in order to provide a force-dependent self-centering mechanism and an improved joint stability against dislocation. The purpose of this study was to determine the relative movements and realignment of different intermediate components during various motion cycles as a result of the eccentric design. We established a validated mathematical model for eccentric dual-mobility systems, which allowed a comparison of relative movements, self-centering torque and overall frictional torque during four different activities in order to analyze their motion behavior in everyday life. In addition, the impact of different radial clearances on the dynamic performance of the self-centering mechanism was investigated. According to torque patterns and the validation experiment, the main articulation of eccentric dual-mobility systems was limited to the smaller inner bearing for the most daily life activities, i.e. the eccentric intermediate component remained in its current position and only with changing activity did the intermediate component realign clearly. However, an inappropriate dimensioning of the radial clearance could lead to a permanent realignment of the intermediate component during the motion cycles. In general, the self-centering mechanism of the intermediate component seems to have no negative influence on relative movements and wear propagation of dual-mobility cup systems if the clearance and eccentricity are appropriately dimensioned.

High-frequency intra-operative ultrasound-guided surgery of superficial intra-cerebral lesions via a single-burr-hole approach.

The study described here examined the feasibility of using high-frequency intra-operative ultrasound (hfioUS) guidance to resect superficial intra-cerebral lesions through a single burr hole. A cohort of 23 consecutive patients with a total of 24 intra-cerebral lesions (9 intra-cerebral metastases, 8 gliomas, 4 infections, 2 lymphomas and 1 cavernoma) were studied. All lesions could be localized and successfully resected, biopsied or aspirated, and histopathological diagnoses were obtained in all cases. The mean operating time was 59.6 ± 23.9 min. The mean cross-sectional lesion size was 6.4 ± 7.6 cm(2), and the mean cortex surface-to-lesion distance was 0.6 ± 0.8 cm. Our results illustrate the feasibility of identifying and resecting superficial intra-cerebral lesions under hfioUS guidance via a single-burr-hole approach. We were able to achieve short resection times with no post-operative complications in all patients, favorable conditions under which to start adjuvant therapy when indicated.

Hydrocephalus after resection and adjuvant radiochemotherapy in patients with glioblastoma.

OBJECTIVE: Glioblastomas are the most common primary malignant brain tumors in adults with a poor prognosis. The current study sought to identify risk factors in glioblastoma patients that are closely associated with communicating hydrocephalus. METHODS: We retrospectively analyzed data from 151 patients who were diagnosed with a glioblastoma between 2007 and 2011 and underwent complete surgical resection closely followed by adjuvant radiochemotherapy. RESULTS: We observed a significant tendency toward communicating hydrocephalus in cases of ventricular opening during surgical tumor resection (Fisher's exact test p<0.001) and a noticeable, although not statistically significant, correlation between the onset of communicating hydrocephalus and evidence of leptomeningeal tumor dissemination (Fisher's exact test p=0.067). Additionally, there was a trend toward frontal tumor location and a larger tumor volume in patients with communicating hydrocephalus. The majority of patients suffering from communicating hydrocephalus received a cerebrospinal fluid (CSF) shunt implantation after radiation therapy (63.6%, Fisher's exact test p=0.000). CONCLUSION: We identified the following risk factors associated with the onset of communicating hydrocephalus in glioblastoma patients: ventricular opening during tumor resection and leptomeningeal tumor dissemination. Shunt implantation seems to be safe and effective in these patients.

Dynamic behavior of tripolar hip endoprostheses under physiological conditions and their effect on stability.

Tripolar systems have been implanted to reduce the risk of recurrent dislocation. However, there is little known about the dynamic behavior of tripolar hip endoprostheses under daily life conditions and achieved joint stability. Hence, the objective of this biomechanical study was to examine the in vivo dynamics and dislocation behavior of two types of tripolar systems compared to a standard total hip replacement (THR) with the same outer head diameter. Several load cases of daily life activities were applied to an eccentric and a concentric tripolar system by an industrial robot. During testing, the motion of the intermediate component was measured using a stereo camera system. Additionally, their behavior under different dislocation scenarios was investigated in comparison to a standard THR. For the eccentric tripolar system, the intermediate component demonstrated the shifting into moderate valgus-positions, regardless of the type of movement. This implant showed the highest resisting torque against dislocation in combination with a large range of motion. In contrast, the concentric tripolar system tended to remain in varus-positions and was primarily moved after stem contact. According to the results, eccentric tripolar systems can work well under in vivo conditions and increase hip joint stability in comparison to standard THRs.