A novel technique, dynamic intraligamentary stabilization creates optimal conditions for primary ACL healing: A preliminary biomechanical study

BACKGROUND Anterior cruciate ligament (ACL) rupture is a common lesion. Current treatment emphasizes arthroscopic ACL reconstruction via a graft, although this approach is associated with potential drawbacks. A new method of dynamic intraligamentary stabilization (DIS) was subjected to biomechanical analysis to determine whether it provides the necessary knee stability for optimal ACL healing. METHODS Six human knees from cadavers were harvested. The patellar tendon, joint capsule and all muscular attachments to the tibia and femur were removed, leaving the collateral and the cruciate ligaments intact. The knees were stabilized and the ACL kinematics analyzed. Anterior-posterior (AP) stability measurements evaluated the knees in the following conditions: (i) intact ACL, (ii) ACL rupture, (iii) ACL rupture with primary stabilization, (iv) primary stabilization after 50 motion cycles, (v) ACL rupture with DIS, and (vi) DIS after 50 motion cycles. RESULTS After primary suture stabilization, average AP laxity was 3.2mm, which increased to an average of 11.26mm after 50 movement cycles. With primary ACL stabilization using DIS, however, average laxity values were consistently lower than those of the intact ligament, increasing from an initial AP laxity of 3.00mm to just 3.2mm after 50 movement cycles. CONCLUSIONS Dynamic intraligamentary stabilization established and maintained close contact between the two ends of the ruptured ACL, thus ensuring optimal conditions for potential healing after primary reconstruction. The present ex vivo findings show that the DIS technique is able to restore AP stability of the knee.

Monitoring cerebral oxygenation during balloon occlusion with multichannel NIRS

We report on oxygenation changes noninvasively recorded by multichannel continuous-wave near infrared spectroscopy (CW-NIRS) during endovascular neuroradiologic interventions requiring temporary balloon occlusion of arteries supplying the cerebral circulation. Digital subtraction angiography (DSA) provides reference data on the site, timing, and effectiveness of the flow stagnation as well as on the amount and direction of collateral circulation. This setting allows us to relate CW-NIRS findings to brain specific perfusion changes. We focused our analysis on the transition from normal perfusion to vessel occlusion, i.e., before hypoxia becomes clinically apparent. The localization of the maximal response correlated either with the core (occlusion of the middle cerebral artery) or with the watershed areas (occlusion of the internal carotid artery) of the respective vascular territories. In one patient with clinically and angiographically confirmed insufficient collateral flow during carotid artery occlusion, the total hemoglobin concentration became significantly asymmetric, with decreased values in the ipsilateral watershed area and contralaterally increased values. Multichannel CW-NIRS monitoring might serve as an objective and early predictive marker of critical perfusion changes during interventions-to prevent hypoxic damage of the brain. It also might provide valuable human reference data on oxygenation changes as they typically occur during acute stroke.

Blocking brain-derived neurotrophic factor inhibits injury-induced hyperexcitability of hippocampal CA3 neurons

Brain trauma can disrupt synaptic connections, and this in turn can prompt axons to sprout and form new connections. If these new axonal connections are aberrant, hyperexcitability can result. It has been shown that ablating tropomyosin-related kinase B (TrkB), a receptor for brain-derived neurotrophic factor (BDNF), can reduce axonal sprouting after hippocampal injury. However, it is unknown whether inhibiting BDNF-mediated axonal sprouting will reduce hyperexcitability. Given this, our purpose here was to determine whether pharmacologically blocking BDNF inhibits hyperexcitability after injury-induced axonal sprouting in the hippocampus. To induce injury, we made Schaffer collateral lesions in organotypic hippocampal slice cultures. As reported by others, we observed a 50% reduction in axonal sprouting in cultures treated with a BDNF blocker (TrkB-Fc) 14 days after injury. Furthermore, lesioned cultures treated with TrkB-Fc were less hyperexcitable than lesioned untreated cultures. Using electrophysiology, we observed a two-fold decrease in the number of CA3 neurons that showed bursting responses after lesion with TrkB-Fc treatment, whereas we found no change in intrinsic neuronal firing properties. Finally, evoked field excitatory postsynaptic potential recordings indicated an increase in network activity within area CA3 after lesion, which was prevented with chronic TrkB-Fc treatment. Taken together, our results demonstrate that blocking BDNF attenuates injury-induced hyperexcitability of hippocampal CA3 neurons. Axonal sprouting has been found in patients with post-traumatic epilepsy. Therefore, our data suggest that blocking the BDNF-TrkB signaling cascade shortly after injury may be a potential therapeutic target for the treatment of post-traumatic epilepsy.

Fixed low-dose ultrasound-assisted catheter-directed thrombolysis followed by routine stenting of residual stenosis for acute ilio-femoral deep-vein thrombosis.

Patients with ilio-femoral deep-vein thrombosis (DVT) are at high risk of developing the post-thrombotic syndrome (PTS). In comparison to anticoagulation therapy alone, extended venography-guided catheter-directed thrombolysis without routine stenting of venous stenosis in patients with ilio-femoral DVT is associated with an increased risk of bleeding and a moderate reduction of PTS. We performed a prospective single-centre study to investigate safety, patency and incidence of PTS in patients with acute ilio-femoral DVT treated with fixed-dose ultrasound-assisted catheter-directed thrombolysis (USAT; 20 mg rt-PA during 15 hours) followed by routing stenting of venous stenosis, defined as residual luminal narrowing >50%, absent antegrade flow, or presence of collateral flow at the site of suspected stenosis. A total of 87 patients (age 46 ± 21 years, 60% women) were included. At 15 hours, thrombolysis success ≥50% was achieved in 67 (77%) patients. Venous stenting (mean 1.9 ± 1.3 stents) was performed in 70 (80%) patients, with the common iliac vein as the most frequent stenting site (83%). One major (1%; 95% CI, 0-6%) and 6 minor bleedings (7%; 95%CI, 3-14%) occurred. Primary and secondary patency rates at 1 year were 87% (95% CI, 74-94%) and 96% (95% CI, 88-99%), respectively. At three months, 88% (95% CI, 78-94%) of patients were free from PTS according to the Villalta scale, with a similar rate at one year (94%, 95% CI, 81-99%). In conclusion, a fixed-dose USAT regimen followed by routine stenting of underlying venous stenosis in patients with ilio-femoral DVT was associated with a low bleeding rate, high patency rates, and a low incidence of PTS.

Arthroscopic approaches to the fetlock joint of adult cattle: a cadaver study

The objective of the present study was to describe the arthroscopic anatomy of the bovine fetlock joint using one palmar/plantar and three dorsal joint approaches. A comparative anatomic, ultrasonographic and arthroscopic study using 20 cadaveric feet from 13 non-lame adult dairy cows was performed. Arthroscopy was accomplished using a rigid arthroscope to view the synovial cavities with their synovial villi and parts of the following structures: the distal ends of the metacarpal/metatarsal III/IV bones with their trochleae and sagittal ridges, synovial grooves, the articular surfaces of the proximal sesamoid bones, the proximal aspects of the first phalanges, the lateral and medial collateral ligaments, the suspensory ligament and the interdigital ligaments as parts of the interosseus muscle, the cruciate sesamoidean ligaments, the communication site between the lateral and medial pouch in the palmar/plantar area, and dorsally the septum between the lateral and the medial pouch. The technique allowed a good overall view of most relevant structures in the sound cadaver joint. Further investigations are warranted to evaluate the diagnostic, therapeutic and prognostic applications of these techniques in the treatment of septic arthritis.

Functional assessment of collaterals in the human coronary circulation.

The coronary collateral circulation is an alternative source of blood supply to a myocardial area jeopardized by the failure of the stenotic or occluded vessel to provide enough blood flow to this region. Until recently, only qualitative or semiqualitative methods have been available for the assessment of the coronary collateral circulation in humans, such as the patient's history of walk-through angina pectoris, the registration of intracoronary ECG signs for myocardial ischaemia or angina pectoris during coronary occlusion, or coronary angiographic classification (score 0-3) of collaterals. Studies of coronary wedge pressure measurements distal of a balloon-occluded coronary artery and the recent advent of ultrathin pressure and Doppler angioplasty guidewires have made it possible to obtain pressure or flow velocity data in remote vascular areas and, thus, to calculate functional variables for coronary collateral flow. Those coronary occlusive pressure- and flow velocity-derived parameters express collateral flow as a fraction of antegrade coronary flow during vessel patency of the collateral-receiving vessel. They are both interchangeable, and they have been validated in comparison to 'traditional' methods and against each other. The possibility of accurately measuring coronary collateral flow indices in humans undergoing coronary balloon angioplasty opens areas of investigation of the pathogenesis, pathophysiology and therapeutic promotion of the collateral circulation previously reserved for exclusively experimental studies. The purpose of this article is to review several clinically available methods for the functional characterization of the coronary collateral circulation.

Determinants of Human Coronary Collaterals.

The human coronary collateral circulation is prognostically relevant. The understanding of collateral formation and its determinants may guide future therapeutic strategies aiming at promoting collateral growth and functionality, and hence reducing the global burden of coronary artery disease (CAD).

Function of Natural Internal Mammary-to-Coronary Artery Bypasses and Its Effect on Myocardial Ischemia.

BACKGROUND The function of naturally existing internal mammary (IMA)-to-coronary artery bypasses and their quantitative effect on myocardial ischemia are unknown. METHODS AND RESULTS The primary end point of this study was collateral flow index (CFI) obtained during two 1-minute coronary artery balloon occlusions, the first with and the second without simultaneous distal IMA occlusion. The secondary study end point was the quantitatively determined intracoronary ECG ST-segment elevation. CFI is the ratio of simultaneously recorded mean coronary occlusive pressure divided by mean aortic pressure both subtracted by mean central venous pressure. A total of 180 pairs of CFI measurements were performed among 120 patients. With and without IMA occlusion, CFI was 0.110±0.074 and 0.096±0.072, respectively (P<0.0001). The difference of CFI obtained in the presence minus CFI obtained in the absence of IMA occlusion was highest and most consistently positive during left IMA with left anterior descending artery occlusion and during right IMA with right coronary artery occlusion (ipsilateral occlusions): 0.033±0.044 and 0.025±0.027, respectively. This CFI difference was absent during right IMA with left anterior descending artery occlusion and during left IMA with right coronary artery occlusion (contralateral occlusions): -0.007±0.034 and 0.001±0.023, respectively (P=0.0002 versus ipsilateral occlusions). The respective CFI differences during either IMA with left circumflex artery occlusion were inconsistently positive. Intracoronary ECG ST-segment elevations were significantly reduced during ipsilateral IMA occlusions but not during contralateral or left circumflex artery occlusions. CONCLUSION There is a functional, ischemia-reducing extracardiac coronary artery supply via ipsilateral but not via contralateral natural IMA bypasses. CLINICAL TRIAL REGISTRATION URL http://www.clinicaltrials.gov. Unique identifier: NCTO1676207.

Pulsed versus continuous wave CO2 laser excisions of 100 oral fibrous hyperplasias: a randomized controlled clinical and histopathological study

BACKGROUND In experimental animal studies, pulsing the CO2 laser beam has been shown to reduce the thermal damage zone of excised oral mucosal tissue. However, there is still controversy over whether this is borne out under clinical conditions. OBJECTIVE To compare the outcome following excisional biopsies of fibrous hyperplasias using a pulsed (cf) versus a continuous wave (cw) CO2 laser mode regarding the thermal damage zone, duration of surgeries, intra- and postoperative complications, postoperative pain sensation, scarring and/or relapse during the initial 6 months. MATERIALS AND METHODS One hundred Swiss-resident patients with a fibrous hyperplasia in their buccal mucosa were randomly assigned to the cw mode (5 W) or the cf mode (140 Hz, 400 microseconds, 33 mJ, 4.62 W) group. All excisions were performed by one single oral surgeon. Postoperative pain (2 weeks) was recorded by visual analogue scale (VAS; ranging from 0 to 100). Intake of analgesics and postoperative complications were recorded in a standardized study form. The maximum width of the collateral thermal damage zone was measured (µm) in excision specimens by one pathologist. Intraoral photographs at 6-month follow-up examinations were evaluated regarding scarring (yes/no). RESULTS Median duration of the excision was 65 seconds in the cw and 81 seconds in the cf group (P = 0.13). Intraoperative bleeding occurred in 16.3% of the patients in the cw and 17.7% of the cf group. The median value of the thermal damage zone was 161(±228) μm in the cw and 152(± 105) μm in the cf group (P = 0.68). The reported postoperative complications included swelling in 19% and minor bleeding in 6% without significant differences between the two laser modes. When comparing each day separately or the combined mean VAS scores of both groups between Days 1-3, 1-7, and 1-15, there were no significant differences. However, more patients of the cw group (25%) took analgesics than patients of the cf group (9.8%) resulting in a borderline significance (P = 0.04). Scarring at the excision site was found in 50.6% of 77 patients after 6 months, and more scars were identified in cases treated with the cf mode (P = 0.03). CONCLUSIONS Excision of fibrous hyperplasias performed with a CO2 laser demonstrated a good clinical outcome and long-term predictability with a low risk of recurrence regardless of the laser mode (cf or cw) used. Scarring after 6 months was only seen in 50.6% of the cases and was slightly more frequent in the cf mode group. Based on the findings of the present study, a safety border of 1 mm appears sufficient for both laser modes especially when performing a biopsy of a suspicious soft tissue lesion to ensure a proper histopathological examination.

Imaging of acute ischemic stroke.

BACKGROUND Over 80% of strokes result from ischemic damage to the brain due to an acute reduction in the blood supply. Around 25-35% of strokes present with large vessel occlusion, and the patients in this category often present with severe neurological deficits. Without early treatment, the prognosis is poor. Stroke imaging is critical for assessing the extent of tissue damage and for guiding treatment. SUMMARY This review focuses on the imaging techniques used in the diagnosis and treatment of acute ischemic stroke, with an emphasis on those involving the anterior circulation. Key Message: Effective and standardized imaging protocols are necessary for clinical decision making and for the proper design of prospective studies on acute stroke. CLINICAL IMPLICATIONS Each minute without treatment spells the loss of an estimated 1.8 million neurons ('time is brain'). Therefore, stroke imaging must be performed in a fast and efficient manner. First, intracranial hemorrhage and stroke mimics should be excluded by the use of computed tomography (CT) or magnetic resonance imaging (MRI). The next key step is to define the extent and location of the infarct core (values of >70 ml, >1/3 of the middle cerebral artery (MCA) territory or an ASPECTS score ≤ 7 indicate poor clinical outcome). Penumbral imaging is currently based on the mismatch concept. It should be noted that the penumbra is a dynamic zone and can be sustained in the presence of good collateral circulation. A thrombus length of >8 mm predicts poor recanalization after intravenous thrombolysis.

Real-time ultra-high optical coherence tomography monitoring of optical tissue effects caused by selective retina therapy

Purpose: Selective retina therapy (SRT) has shown great promise compared to conventional retinal laser photocoagulation as it avoids collateral damage and selectively targets the retinal pigment epithelium (RPE). Its use, however, is challenging in terms of therapy monitoring and dosage because an immediate tissue reaction is not biomicroscopically discernibel. To overcome these limitations, real-time optical coherence tomography (OCT) might be useful to monitor retinal tissue during laser application. We have thus evaluated a proprietary OCT system for its capability of mapping optical changes introduced by SRT in retinal tissue. Methods: Freshly enucleated porcine eyes, covered in DMEM upon collection were utilized and a total of 175 scans from ex-vivo porcine eyes were analyzed. The porcine eyes were used as an ex-vivo model and results compared to two time-resolved OCT scans, recorded from a patient undergoing SRT treatment (SRT Vario, Medical Laser Center Lübeck). In addition to OCT, fluorescin angiography and fundus photography were performed on the patient and OCT scans were subsequently investigated for optical tissue changes linked to laser application. Results: Biomicroscopically invisible SRT lesions were detectable in OCT by changes in the RPE / Bruch's complex both in vivo and the porcine ex-vivo model. Laser application produced clearly visible optical effects such as hyperreflectivity and tissue distortion in the treated retina. Tissue effects were even discernible in time-resolved OCT imaging when no hyper-reflectivity persisted after treatment. Data from ex-vivo porcine eyes showed similar to identical optical changes while effects visible in OCT appeared to correlate with applied pulse energy, leading to an additional reflective layer when lesions became visible in indirect ophthalmoscopy. Conclusions: Our results support the hypothesis that real-time high-resolution OCT may be a promising modality to obtain additional information about the extent of tissue damage caused by SRT treatment. Data shows that our exvivo porcine model adequately reproduces the effects occurring in-vivo, and thus can be used to further investigate this promising imaging technique.

Cosmogenic 180W variations in meteorites and re-assessment of a possible 184Os–180W decay system

We measured tungsten (W) isotopes in 23 iron meteorites and the metal phase of the CB chondrite Gujba in order to ascertain if there is evidence for a large-scale nucleosynthetic heterogeneity in the p-process isotope 180W in the solar nebula as recently suggested by Schulz et al. (2013). We observed large excesses in 180W (up to ≈ 6 ε) in some irons. However, significant within-group variations in magmatic IIAB and IVB irons are not consistent with a nucleosynthetic origin, and the collateral effects on 180W from an s-deficit in IVB irons cannot explain the total variation. We present a new model for the combined effects of spallation and neutron capture reactions on 180W in iron meteorites and show that at least some of the observed within-group variability is explained by cosmic ray effects. Neutron capture causes burnout of 180W, whereas spallation reactions lead to positive shifts in 180W. These effects depend on the target composition and cosmic-ray exposure duration; spallation effects increase with Re/W and Os/W ratios in the target and with exposure age. The correlation of 180W/184W with Os/W ratios in iron meteorites results in part from spallogenic production of 180W rather than from 184Os decay, contrary to a recent study by Peters et al. (2014). Residual ε180W excesses after correction for an s-deficit and for cosmic ray effects may be due to ingrowth of 180W from 184Os decay, but the magnitude of this ingrowth is at least a factor of ≈2 smaller than previously suggested. These much smaller effects strongly limit the applicability of the putative 184Os-180W system to investigate geological problems.

Protected stent retriever thrombectomy prevents iatrogenic emboli in new vascular territories

INTRODUCTION Diagnostic tools to show emboli reliably and protection techniques against embolization when employing stent retrievers are necessary to improve endovascular stroke therapy. The aim of the present study was to investigate iatrogenic emboli using susceptibility-weighted imaging (SWI) in an open series of patients who had been treated with stent retriever thrombectomy using emboli protection techniques. METHODS Patients with anterior circulation stroke examined with MRI before and after stent retriever thrombectomy were assessed for iatrogenic embolic events. Thrombectomy was performed in flow arrest and under aspiration using a balloon-mounted guiding catheter, a distal access catheter, or both. RESULTS In 13 of 57 patients (22.8 %) post-interventional SWI sequences detected 16 microemboli. Three of them were associated with small ischemic lesions on diffusion-weighted imaging (DWI). None of the microemboli were located in a new vascular territory, none showed clinical signs, and all 13 patients have been rated as Thrombolysis in Cerebral Infarction (TICI) 2b (n = 3) or 3 (n = 10). Retrospective reevaluation of the digital subtraction angiography (DSA) detected discrete flow stagnation nearby the iatrogenic microemboli in four patients with a positive persistent collateral sign in one. CONCLUSION Our study demonstrates two things: First, SWI seems to be more sensitive to detect emboli than DWI and DSA and, second, proximal or distal protected stent retriever thrombectomy seems to prevent iatrogenic embolization into new vascular territories during retraction of the thrombus, but not downstream during mobilization of the thrombus. Both techniques should be investigated and refined further.

Infarction Distribution Pattern in Acute Stroke May Predict the Extent of Leptomeningeal Collaterals.

OBJECTIVE The aim of this study was to evaluate whether the distribution pattern of early ischemic changes in the initial MRI allows a practical method for estimating leptomeningeal collateralization in acute ischemic stroke (AIS). METHODS Seventy-four patients with AIS underwent MRI followed by conventional angiogram and mechanical thrombectomy. Diffusion restriction in Diffusion weighted imaging (DWI) and correlated T2-hyperintensity of the infarct were retrospectively analyzed and subdivided in accordance with Alberta Stroke Program Early CT score (ASPECTS). Patients were angiographically graded in collateralization groups according to the method of Higashida, and dichotomized in 2 groups: 29 subjects with collateralization grade 3 or 4 (well-collateralized group) and 45 subjects with grade 1 or 2 (poorly-collateralized group). Individual ASPECTS areas were compared among the groups. RESULTS Means for overall DWI-ASPECTS were 6.34 vs. 4.51 (well vs. poorly collateralized groups respectively), and for T2-ASPECTS 9.34 vs 8.96. A significant difference between groups was found for DWI-ASPECTS (p<0.001), but not for T2-ASPECTS (p = 0.088). Regarding the individual areas, only insula, M1-M4 and M6 showed significantly fewer infarctions in the well-collateralized group (p-values <0.001 to 0.015). 89% of patients in the well-collateralized group showed 0-2 infarctions in these six areas (44.8% with 0 infarctions), while 59.9% patients of the poor-collateralized group showed 3-6 infarctions. CONCLUSION Patients with poor leptomeningeal collateralization show more infarcts on the initial MRI, particularly in the ASPECTS areas M1 to M4, M6 and insula. Therefore DWI abnormalities in these areas may be a surrogate marker for poor leptomeningeal collaterals and may be useful for estimation of the collateral status in routine clinical evaluation.

Screening for Rheumatic Heart Disease among Peruvian Children: A Two-Stage Sampling Observational Study.

BACKGROUND The objective of the study was to evaluate the implications of different classifications of rheumatic heart disease on estimated prevalence, and to systematically assess the importance of incidental findings from echocardiographic screening among schoolchildren in Peru. METHODS We performed a cluster randomized observational survey using portable echocardiography among schoolchildren aged 5 to 16 years from randomly selected public and private schools in Arequipa, Peru. Rheumatic heart disease was defined according to the modified World Health Organization (WHO) criteria and the World Heart Federation (WHF) criteria. FINDINGS Among 1395 eligible students from 40 classes and 20 schools, 1023 (73%) participated in the present survey. The median age of the children was 11 years (interquartile range [IQR] 8-13 years) and 50% were girls. Prevalence of possible, probable and definite rheumatic heart disease according to the modified WHO criteria amounted to 19.7/1000 children and ranged from 10.2/1000 among children 5 to 8 years of age to 39.8/1000 among children 13 to 16 years of age; the prevalence of borderline/definite rheumatic heart disease according to the WHF criteria was 3.9/1000 children. 21 children (2.1%) were found to have congenital heart disease, 8 of which were referred for percutaneous or surgical intervention. CONCLUSIONS Prevalence of RHD in Peru was considerably lower compared to endemic regions in sub-Saharan Africa, southeast Asia, and Oceania; and paralleled by a comparable number of undetected congenital heart disease. Strategies to address collateral findings from echocardiographic screening are necessary in the setup of active surveillance programs for RHD. TRIAL REGISTRATION ClinicalTrials.gov identifier: NCT02353663.