Deep Neural Networks for Automated Outer Plexiform Layer Subsidence Detection on Retinal OCT of Patients With Intermediate AMD.

Purpose: The subsidence of the outer plexiform layer (OPL) is an important imaging biomarker on optical coherence tomography (OCT) associated with early outer retinal atrophy and a risk factor for progression to geographic atrophy in patients with intermediate age-related macular degeneration (AMD). Deep neural networks (DNNs) for OCT can support automated detection and localization of this biomarker. Methods: The method predicts potential OPL subsidence locations on retinal OCTs. A detection module (DM) infers bounding boxes around subsidences with a likelihood score, and a classification module (CM) assesses subsidence presence at the B-scan level. Overlapping boxes between B-scans are combined and scored by the product of the DM and CM predictions. The volume-wise score is the maximum prediction across all B-scans. One development and one independent external data set were used with 140 and 26 patients with AMD, respectively. Results: The system detected more than 85% of OPL subsidences with less than one false-positive (FP)/scan. The average area under the curve was 0.94 ± 0.03 for volume-level detection. Similar or better performance was achieved on the independent external data set. Conclusions: DNN systems can efficiently perform automated retinal layer subsidence detection in retinal OCT images. In particular, the proposed DNN system detects OPL subsidence with high sensitivity and a very limited number of FP detections. Translational Relevance: DNNs enable objective identification of early signs associated with high risk of progression to the atrophic late stage of AMD, ideally suited for screening and assessing the efficacy of the interventions aiming to slow disease progression.

Deep Learning-Based Prediction of Individual Geographic Atrophy Progression from a Single Baseline OCT.

Objective: To identify the individual progression of geographic atrophy (GA) lesions from baseline OCT images of patients in routine clinical care. Design: Clinical evaluation of a deep learning-based algorithm. Subjects: One hundred eighty-four eyes of 100 consecutively enrolled patients. Methods: OCT and fundus autofluorescence (FAF) images (both Spectralis, Heidelberg Engineering) of patients with GA secondary to age-related macular degeneration in routine clinical care were used for model validation. Fundus autofluorescence images were annotated manually by delineating the GA area by certified readers of the Vienna Reading Center. The annotated FAF images were anatomically registered in an automated manner to the corresponding OCT scans, resulting in 2-dimensional en face OCT annotations, which were taken as a reference for the model performance. A deep learning-based method for modeling the GA lesion growth over time from a single baseline OCT was evaluated. In addition, the ability of the algorithm to identify fast progressors for the top 10%, 15%, and 20% of GA growth rates was analyzed. Main Outcome Measures: Dice similarity coefficient (DSC) and mean absolute error (MAE) between manual and predicted GA growth. Results: The deep learning-based tool was able to reliably identify disease activity in GA using a standard OCT image taken at a single baseline time point. The mean DSC for the total GA region increased for the first 2 years of prediction (0.80-0.82). With increasing time intervals beyond 3 years, the DSC decreased slightly to a mean of 0.70. The MAE was low over the first year and with advancing time slowly increased, with mean values ranging from 0.25 mm to 0.69 mm for the total GA region prediction. The model achieved an area under the curve of 0.81, 0.79, and 0.77 for the identification of the top 10%, 15%, and 20% growth rates, respectively. Conclusions: The proposed algorithm is capable of fully automated GA lesion growth prediction from a single baseline OCT in a time-continuous fashion in the form of en face maps. The results are a promising step toward clinical decision support tools for therapeutic dosing and guidance of patient management because the first treatment for GA has recently become available. Financial Disclosures: Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Deep Multimodal Fusion of Data With Heterogeneous Dimensionality via Projective Networks.

The use of multimodal imaging has led to significant improvements in the diagnosis and treatment of many diseases. Similar to clinical practice, some works have demonstrated the benefits of multimodal fusion for automatic segmentation and classification using deep learning-based methods. However, current segmentation methods are limited to fusion of modalities with the same dimensionality (e.g., 3D + 3D, 2D + 2D), which is not always possible, and the fusion strategies implemented by classification methods are incompatible with localization tasks. In this work, we propose a novel deep learning-based framework for the fusion of multimodal data with heterogeneous dimensionality (e.g., 3D + 2D) that is compatible with localization tasks. The proposed framework extracts the features of the different modalities and projects them into the common feature subspace. The projected features are then fused and further processed to obtain the final prediction. The framework was validated on the following tasks: segmentation of geographic atrophy (GA), a late-stage manifestation of age-related macular degeneration, and segmentation of retinal blood vessels (RBV) in multimodal retinal imaging. Our results show that the proposed method outperforms the state-of-the-art monomodal methods on GA and RBV segmentation by up to 3.10% and 4.64% Dice, respectively.

Learning Spatio-Temporal Model of Disease Progression With NeuralODEs From Longitudinal Volumetric Data.

Robust forecasting of the future anatomical changes inflicted by an ongoing disease is an extremely challenging task that is out of grasp even for experienced healthcare professionals. Such a capability, however, is of great importance since it can improve patient management by providing information on the speed of disease progression already at the admission stage, or it can enrich the clinical trials with fast progressors and avoid the need for control arms by the means of digital twins. In this work, we develop a deep learning method that models the evolution of age-related disease by processing a single medical scan and providing a segmentation of the target anatomy at a requested future point in time. Our method represents a time-invariant physical process and solves a large-scale problem of modeling temporal pixel-level changes utilizing NeuralODEs. In addition, we demonstrate the approaches to incorporate the prior domain-specific constraints into our method and define temporal Dice loss for learning temporal objectives. To evaluate the applicability of our approach across different age-related diseases and imaging modalities, we developed and tested the proposed method on the datasets with 967 retinal OCT volumes of 100 patients with Geographic Atrophy and 2823 brain MRI volumes of 633 patients with Alzheimer's Disease. For Geographic Atrophy, the proposed method outperformed the related baseline models in the atrophy growth prediction. For Alzheimer's Disease, the proposed method demonstrated remarkable performance in predicting the brain ventricle changes induced by the disease, achieving the state-of-the-art result on TADPOLE cross-sectional prediction challenge dataset.

Deep survival modeling of longitudinal retinal OCT volumes for predicting the onset of atrophy in patients with intermediate AMD.

In patients with age-related macular degeneration (AMD), the risk of progression to late stages is highly heterogeneous, and the prognostic imaging biomarkers remain unclear. We propose a deep survival model to predict the progression towards the late atrophic stage of AMD. The model combines the advantages of survival modelling, accounting for time-to-event and censoring, and the advantages of deep learning, generating prediction from raw 3D OCT scans, without the need for extracting a predefined set of quantitative biomarkers. We demonstrate, in an extensive set of evaluations, based on two large longitudinal datasets with 231 eyes from 121 patients for internal evaluation, and 280 eyes from 140 patients for the external evaluation, that this model improves the risk estimation performance over standard deep learning classification models.

The Effect of Pegcetacoplan Treatment on Photoreceptor Maintenance in Geographic Atrophy Monitored by Artificial Intelligence-Based OCT Analysis.

PURPOSE: To investigate the therapeutic effect of intravitreal pegcetacoplan on the inhibition of photoreceptor (PR) loss and thinning in geographic atrophy (GA) on conventional spectral-domain OCT (SD-OCT) imaging by deep learning-based automated PR quantification. DESIGN: Post hoc analysis of a prospective, multicenter, randomized, sham (SM)-controlled, masked phase II trial investigating the safety and efficacy of pegcetacoplan for the treatment of GA because of age-related macular degeneration. PARTICIPANTS: Study eyes of 246 patients, randomized 1:1:1 to monthly (AM), bimonthly (AEOM), and SM treatment. METHODS: We performed fully automated, deep learning-based segmentation of retinal pigment epithelium (RPE) loss and PR thickness on SD-OCT volumes acquired at baseline and months 2, 6, and 12. The difference in the change of PR loss area was compared among the treatment arms. Change in PR thickness adjacent to the GA borders and the entire 20° scanning area was compared between treatment arms. MAIN OUTCOME MEASURES: Square-root transformed PR loss area in µm or mm, PR thickness in µm, and PR loss/RPE loss ratio. RESULTS: A total of 31 556 B-scans of 644 SD-OCT volumes of 161 study eyes (AM 52, AEOM 54, SM 56) were evaluated from baseline to month 12. Comparison of the mean change in PR loss area revealed statistically significantly less growth in the AM group at months 2, 6, and 12 than in the SM group (-41 µm ± 219 vs. 77 µm ± 126; P = 0.0004; -5 µm ± 221 vs. 156 µm ± 139; P < 0.0001; 106 µm ± 400 vs. 283 µm ± 226; P = 0.0014). Photoreceptor thinning was significantly reduced under AM treatment compared with SM within the GA junctional zone, as well as throughout the 20° area. A trend toward greater inhibition of PR loss than RPE loss was observed under therapy. CONCLUSIONS: Distinct and reliable quantification of PR loss using deep learning-based algorithms offers an essential tool to evaluate therapeutic efficacy in slowing disease progression. Photoreceptor loss and thinning are reduced by intravitreal complement C3 inhibition. Automated quantification of PR loss/maintenance based on OCT images is an ideal approach to reliably monitor disease activity and therapeutic efficacy in GA management in clinical routine and regulatory trials.

Fundus autofluorescence and optical coherence tomography biomarkers associated with the progression of geographic atrophy secondary to age-related macular degeneration.

OBJECTIVES: To investigate the impact of qualitatively graded and deep learning quantified imaging biomarkers on growth of geographic atrophy (GA) secondary to age-related macular degeneration. METHODS: This prospective study included 1062 visits of 181 eyes of 100 patients with GA. Spectral-domain optical coherence tomography (SD-OCT) and fundus autofluorescence (FAF) images were acquired at each visit. Hyperreflective foci (HRF) were quantitatively assessed in SD-OCT volumes using a validated deep learning algorithm. FAF images were graded for FAF patterns, subretinal drusenoid deposits (SDD), GA lesion configuration and atrophy enlargement. Linear mixed models were calculated to investigate associations between all parameters and GA progression. RESULTS: FAF patterns were significantly associated with GA progression (p < 0.001). SDD was associated with faster GA growth (p = 0.005). Eyes with higher HRF concentrations showed a trend towards faster GA progression (p = 0.072) and revealed a significant impact on GA enlargement in interaction with FAF patterns (p = 0.01). The fellow eye status had no significant effect on lesion enlargement (p > 0.05). The diffuse-trickling FAF pattern exhibited significantly higher HRF concentrations than any other pattern (p < 0.001). CONCLUSION: Among a wide range of investigated biomarkers, SDD and FAF patterns, particularly in interaction with HRF, significantly impact GA progression. Fully automated quantification of retinal imaging biomarkers such as HRF is both reliable and merited as HRF are indicators of retinal pigment epithelium dysmorphia, a central pathogenetic mechanism in GA. Identifying disease markers using the combination of FAF and SD-OCT is of high prognostic value and facilitates individualized patient management in a clinical setting.

Danger zone - The spermatic cord during anterior plating of the symphysis pubis.

BACKGROUND: Distances between anatomic landmarks and anatomic structures at risk are often underestimated by surgeons. PURPOSE: The goal of the study was to evaluate the distances between anatomic landmarks and the spermatic cord in case of anterior plating of the symphysis. METHODS: A total of 25 pelves (50 hemipelves) of male embalmed cadavers were dissected. A 5-hole 3.5mm locking compression plate (Synthes GmbH) was fixed from directly anterior on the symphysis. Measurements were taken 1) distance between the tips of both pubic tubercles, 2) horizontal interval between the lateral border of the plate and the medial margin of the SC (bilateral), 3) distances between the medial border of the SC and the tip of the pubic tubercle (bilateral), 4) distances between the medial border of the SC and the lateral basis of the pubic tubercle (bilateral). RESULTS: The distance between the pubic tubercles was 60.3mm in average (SD: 5.7). The interval between the lateral border of the plate and the medial margin of the SC was on average 4.5mm (SD: 1.9) on the right and 4.7mm (SD: 2.6) on the left side. The distance between the tip of the pubic tubercle and the medial border of the SC was in average 11.2mm (SD: 2.7) on the right, and 11.0mm (SD: 2.7) on the left side. The average distance between the medial border of the SC and the lateral basis of the pubic tubercle was 8.1mm (SD: 2.4) on the right and 8.2 mm (SD: 2.4) on the left side. CONCLUSION: The SC is at risk not only during dissection but also during anterior plating of the symphysis, because of its close relation to the SC. CLINICAL RELEVANCE: Average distances between the palpable pubic tubercle and the SC are below one finger breadth (as reference).

Relation of the lumbosacral trunk to the sacro-iliac joint.

This study aims to evaluate the relation between the lumbosacral trunk (LT) and the sacro-iliac joint (SIJ). In forty anatomic specimens (hemipelves) a classical antero-lateral approach to the SIJ was performed. The SIJ was marked at the linea terminalis (reference point A). Reference point B was situated at the upper edge of the interosseous sacro-iliac ligament. The length of the SIJ (distance A to B) and the distance between point A and the ventral branch of the fourth (L4) and fifth (L5) lumbar spinal nerves at the linea terminalis were measured. The SIJ had a mean length of 58.0 mm. The ventral branch of L5 was located closer to the SIJ in very long SIJs (mean length: ≥ 6.5 cm; mean distance: 9.8 mm) compared to very short joints (≤ 5 mm; mean distance: 11.3 mm). For the ventral branch of L4, very long SIJs had a mean distance of 7 mm and very short joints an average distance of 9.7 mm between point A and the nerve branch. A safe zone of approximately 1 cm to 2 cm (anterior to posterior) is present on the sacral surface (lateral to medial) for safe fixation of plates during anterior plate stabilization of the SIJ. Pelves with a shorter dorsoventral diameter of the most superior part of the SIJ apparently give more space for inserting plates.

IMPACT OF RESIDUAL SUBRETINAL FLUID VOLUMES ON TREATMENT OUTCOMES IN A SUBRETINAL FLUID-TOLERANT TREAT-AND-EXTEND REGIMEN.

PURPOSE: To investigate associations between residual subretinal fluid (rSRF) volumes, quantified using artificial intelligence and treatment outcomes in a subretinal fluid (SRF)-tolerant treat-and-extend (T&E) regimen in neovascular age-related macular degeneration. METHODS: Patients enrolled in the prospective, multicenter FLUID study randomized in an SRF-tolerant T&E regimen were examined by spectral-domain optical coherence tomography and tested for best-corrected visual acuity (BCVA). Intraretinal fluid and SRF volumes were quantified using artificial intelligence tools. In total, 375 visits of 98 patients were divided into subgroups: extended intervals despite rSRF and extended intervals without fluid. Associations between BCVA change, SRF volume, subgroups, and treatment intervals were estimated using linear mixed models. RESULTS: In extended intervals despite rSRF, increased SRF was associated with reduced BCVA at the next visit in the central 1 mm (-0.138 letters per nL; P = 0.014) and 6 mm (-0.024 letters per nL; P = 0.049). A negative association between increased interval and BCVA change was found for rSRF in 1 mm and 6 mm (-0.250 and -0.233 letter per week interval, respectively; both P < 0.001). Extended intervals despite rSRF had significantly higher SRF volumes in the central 6 mm at the following visit (P = 0.002). CONCLUSION: Artificial intelligence-based analysis of extended visits despite rSRF demonstrated increasing SRF volumes associated with BCVA loss at the consecutive visit. This negative association contributes to the understanding of rSRF volumes on treatment outcomes in neovascular age-related macular degeneration.

The articular branch of the peroneal nerve to the proximal tibiofibular joint descends at a mean height of approximately 18 mm distal to the postero-lateral tip of the fibular head.

PURPOSE: The aim of the study was to evaluate the anatomical details of the articular branch of the peroneal nerve to the proximal tibiofibular joint and to project the height of its descent in relation to the fibular length. METHODS: Twenty-five lower extremities were included in the study. Following identification of the common peroneal nerve, its course was traced to its division into the deep and superficial peroneal nerve. The articular branch was identified. The postero-lateral tip of the fibular head was marked and the interval from this landmark to the diversion of the articular branch was measured. The length of the fibula, as the interval between the postero-lateral tip of the fibular head and the tip of the lateral malleolus, was evaluated. The quotient of descending point of the articular branch in relation to the individual fibular length was calculated. RESULTS: The articular branch descended either from the common peroneal nerve or the deep peroneal nerve. The descending point was located at a mean height of 18.1 mm distal to the postero-lateral tip of the fibular head. Concerning the relation to the fibular length, this was at a mean of 5.1%, starting from the same reference point. CONCLUSION: The articular branch of the common peroneal nerve was located at a mean height of 18.1 mm distal to the the postero-lateral tip of the fibular head, respectively, at a mean of 5.1% of the whole fibular length starting from the same reference point. These details represent a convenient orientation during surgical treatment of intraneural ganglia of the common peroneal nerve, which may result directly from knee trauma and indirectly from ankle sprain.

ANALYSIS OF FLUID VOLUME AND ITS IMPACT ON VISUAL ACUITY IN THE FLUID STUDY AS QUANTIFIED WITH DEEP LEARNING.

PURPOSE: To investigate quantitative differences in fluid volumes between subretinal fluid (SRF)-tolerant and SRF-intolerant treat-and-extend regimens for neovascular age-related macular degeneration and analyze the association with best-corrected visual acuity. METHODS: Macular fluid (SRF and intraretinal fluid) was quantified on optical coherence tomography volumetric scans using a trained and validated deep learning algorithm. Fluid volumes and complete resolution was automatically assessed throughout the study. The impact of fluid location and volumes on best-corrected visual acuity was computed using mixed-effects regression models. RESULTS: Baseline fluid quantifications for 348 eyes from 348 patients were balanced (all P > 0.05). No quantitative differences in SRF/intraretinal fluid between the treatment arms was found at any study-specific time point (all P > 0.05). Compared with qualitative assessment, the proportion of eyes without SRF/intraretinal fluid did not differ between the groups at any time point (all P > 0.05). Intraretinal fluid in the central 1 mm and SRF in the 1-mm to 6-mm macular area were negatively associated with best-corrected visual acuity (-2.8 letters/100 nL intraretinal fluid, P = 0.007 and -0.20 letters/100 nL SRF, P = 0.005, respectively). CONCLUSION: Automated fluid quantification using artificial intelligence allows objective and precise assessment of macular fluid volume and location. Precise determination of fluid parameters will help improve therapeutic efficacy of treatment in neovascular age-related macular degeneration.

Dual-incision minimally invasive fasciotomy of the anterior and peroneal compartments for chronic exertional compartment syndrome of the lower leg.

To evaluate the risk of iatrogenic injury when using a dual-incision minimally invasive technique to decompress the anterior and peroneal compartments of the lower leg. Forty lower extremities from 20 adult cadavers, embalmed with Thiel's method, were subject to fasciotomy of the anterior and peroneal compartment using a dual-incision minimally invasive fasciotomy. The first incision was made 12 cm proximal to the lateral malleolus to identify and protect the superficial peroneal nerve (SPN). The second incision was made at the mid-point of the Fibula (half-way between the fibular head and the lateral malleolus). Release of the anterior and peroneal compartments was successful in all specimens. Two nerve injuries of the superficial peroneal nerve were reported. More precisely, in these cases the medial dorsal cutaneous nerve got injured during the fascial opening of the extensor compartment. Two incision minimally invasive fasciotomy to decompress the anterior and peroneal compartments of the lower leg appears to be safe with regard to the results of this study.

Role of Deep Learning-Quantified Hyperreflective Foci for the Prediction of Geographic Atrophy Progression.

PURPOSE: To quantitatively measure hyperreflective foci (HRF) during the progression of geographic atrophy (GA) secondary to age-related macular degeneration (AMD) using deep learning (DL) and investigate the association with local and global growth of GA. METHODS: Eyes with GA were prospectively included. Spectral-domain optical coherence tomography (SDOCT) and fundus autofluorescence images were acquired every 6 months. A 500-µm-wide junctional zone adjacent to the GA border was delineated and HRF were quantified using a validated DL algorithm. HRF concentrations in progressing and nonprogressing areas, as well as correlations between HRF quantifications and global and local GA progression, were assessed. RESULTS: A total of 491 SDOCT volumes from 87 eyes of 54 patients were assessed with a median follow-up of 28 months. Two-thirds of HRF were localized within a millimeter adjacent to the GA border. HRF concentration was positively correlated with GA progression in unifocal and multifocal GA (all P < .001) and de novo GA development (P = .037). Local progression speed correlated positively with local increase of HRF (P value range <.001-.004). Global progression speed, however, did not correlate with HRF concentrations (P > .05). Changes in HRF over time did not have an impact on the growth in GA (P > .05). CONCLUSION: Advanced artificial intelligence (AI) methods in high-resolution retinal imaging allows to identify, localize, and quantify biomarkers such as HRF. Increased HRF concentrations in the junctional zone and future macular atrophy may represent progressive migration and loss of retinal pigment epithelium. AI-based biomarker monitoring may pave the way into the era of individualized risk assessment and objective decision-making processes. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

Automated Quantification of Photoreceptor alteration in macular disease using Optical Coherence Tomography and Deep Learning.

Diabetic macular edema (DME) and retina vein occlusion (RVO) are macular diseases in which central photoreceptors are affected due to pathological accumulation of fluid. Optical coherence tomography allows to visually assess and evaluate photoreceptor integrity, whose alteration has been observed as an important biomarker of both diseases. However, the manual quantification of this layered structure is challenging, tedious and time-consuming. In this paper we introduce a deep learning approach for automatically segmenting and characterising photoreceptor alteration. The photoreceptor layer is segmented using an ensemble of four different convolutional neural networks. En-face representations of the layer thickness are produced to characterize the photoreceptors. The pixel-wise standard deviation of the score maps produced by the individual models is also taken to indicate areas of photoreceptor abnormality or ambiguous results. Experimental results showed that our ensemble is able to produce results in pair with a human expert, outperforming each of its constitutive models. No statistically significant differences were observed between mean thickness estimates obtained from automated and manually generated annotations. Therefore, our model is able to reliable quantify photoreceptors, which can be used to improve prognosis and managment of macular diseases.

TOPOGRAPHIC ANALYSIS OF PHOTORECEPTOR LOSS CORRELATED WITH DISEASE MORPHOLOGY IN NEOVASCULAR AGE-RELATED MACULAR DEGENERATION.

PURPOSE: To quantify morphologic photoreceptor integrity during anti-vascular endothelial growth factor (anti-VEGF) therapy of neovascular age-related macular degeneration and correlate these findings with disease morphology and function. METHODS: This presents a post hoc analysis on spectral-domain optical coherence tomography data of 185 patients, acquired at baseline, Month 3, and Month 12 in a multicenter, prospective trial. Loss of the ellipsoid zone (EZ) was manually quantified in all optical coherence tomography volumes. Intraretinal cystoid fluid, subretinal fluid (SRF), and pigment epithelial detachments were automatically segmented in the full volumes using validated deep learning methods. Spatiotemporal correlation of fluid markers with EZ integrity as well as bivariate analysis between EZ integrity and best-corrected visual acuity was performed. RESULTS: At baseline, EZ integrity was predominantly impaired in the fovea, showing progressive recovery during anti-vascular endothelial growth factor therapy. Topographic analysis at baseline revealed EZ integrity to be more likely intact in areas with SRF and vice versa. Moreover, we observed a correlation between EZ integrity and resolution of SRF. Foveal EZ integrity correlated with best-corrected visual acuity at all timepoints. CONCLUSION: Improvement of EZ integrity during anti-VEGF therapy of neovascular age-related macular degeneration occurred predominantly in the fovea. Photoreceptor integrity correlated with best-corrected visual acuity. Ellipsoid zone integrity was preserved in areas of SRF and showed deterioration upon SRF resolution.

Success Rate in Puncture of the Temporomandibular Joint.

Puncture of the temporomandibular joint (TMJ) is a minimally invasive treatment for various jaw disorders. This study used a cadaveric model to evaluate the procedure from two entrance points with respect to hit ratio and possible complications, such as extraarticular extrusion of injection fluid. Ten heads, embalmed with Thiel's method, were investigated. A straight line drawn with a colored pen connected the center of the tragus and the lateral canthus. The first portal "A" was located at a distance of 1 cm anterior and 2 mm caudal from the center of the tragus. Portal "B" was located 2 cm anterior and 1 cm caudal starting from the same reference point. Punctures "A" and "B" were performed alternately on the right and left sides. Specimens were dissected and the local distribution of the injected latex was recorded. With Approach A, four punctures (40%; 4/10) reached the TMJ, whereas with Approach B, six injections (60%; 6/10) entered the TMJ. There were no statistically significant differences between the tested puncture methods (P = 0.0317) and body sides (P = 1). With each method, for example, 35% (7/20) each, the injected latex was either periarticular or retromandibular. In a further 20% (4/20), it was located subperiosteally alongside the ramus of mandible. The latex was injected into the infratemporal fossa and the external acoustic meatus in one case each (each 5%). There was no statistically significant difference between the techniques. The adjacent anatomy has to be kept in mind during TMJ puncture as the complication rate was remarkably high, suggesting that ultrasound guided intraarticular injection could improve the hit rate. Clin. Anat., 33:683-688, 2020. © 2019 Wiley Periodicals, Inc.

Safe zone for the posterior interosseous nerve with regard to the lateral and posterior approaches to the proximal radius.

PURPOSE: The posterior interosseous nerve (PIN) is at risk during the posterior and lateral approaches to the proximal radius. We aimed to define a safe zone for these approaches to avoid injury of the PIN and to evaluate their close and changing relationship to the nerve during forearm rotation. METHODS: The study collective consisted of 50 upper limbs. After performance of the lateral approach, the distance between the tip of the radial head and the PIN's exit point from the supinator (= distance 1) and the shortest interval between the nerve's exit to the radial margin of the ulna (= distance 2) were measured in maximum pronation and supination. Then, the dorsal approach was conducted and again distance 1 and the interval between the distal margin of the anconeus and the nerve's exit point (distance 2) were evaluated (pronation and supination). RESULTS: There were significantly shorter distances during supination in comparison to pronation. Regarding the lateral approach, distance 1 changed from a mean of 60.3 mm (supination) to 62.7 mm in pronation (p < 0.001). For the dorsal approach, distance 1 decreased significantly (p < 0.001) from 62.9 mm (pronation) to 60.2 mm (supination). CONCLUSION: Supination during the lateral and dorsal approaches to the proximal radius needs to be avoided to protect the PIN. Furthermore, the nerve appeared at an interval between 45 and 84.1 mm (lateral approach) and 47.5-93.8 mm (dorsal approach), respectively. Therefore, care must be taken at this height during extension of the approaches in a distal direction.

Variations of treatment in selected proximal femur fractures among surgeons with different surgical experience--A survey at an international AO course.

INTRODUCTION: Different modalities of treatment for hip fractures have been discussed in the literature; however, practice may vary between centres. A survey was conducted on participants at an international AO course to assess the current management of pertrochanteric fractures (AO/OTA 31-A2) and displaced, non-impacted, subcapital fractures (AO/OTA 31-B3) in a 35-year-old patient and an 85-year-old patient. METHODS: Surgeons taking part in an international orthopaedic course were invited to participate in a survey and were divided into two groups: inexperienced (one-to-three years since qualification) and experienced (four or more years). A survey was conducted to assess the management modalities used for pertrochanteric fractures (AO/OTA 31-A2) and displaced, non-impacted, subcapital fractures (AO/OTA 31-B3) in a 35-year-old patient and an 85-year-old patient. RESULTS: Fifty-two surgeons participated: 18 were inexperienced and 34 were experienced. The method of operative fixation for the pertrochanteric fracture was gamma-nailing for 95% of the surgeons in the inexperienced group; in the experienced group, 56% opted for gamma-nailing and 38% for dynamic hip screw (DHS). For the displaced subcapital fracture in a 35-year-old, screw fixation was the dominant treatment option for both groups. For the displaced subcapital fracture in an 85-year-old, most of the surgeons in both groups preferred hemiarthroplasty: 59% in the inexperienced group chose cemented bipolar hemiarthroplasty and 12% uncemented, whereas 56% of the experienced group suggested cemented bipolar hemiarthroplasty and 25% uncemented. DISCUSSION: This survey shows that a variety of methods are used to treat femoral neck fractures. A prospective randomised trial has shown the DHS to be the implant of choice for pertrochanteric fractures; however, this was not considered an option in the inexperienced group of surgeons and was the treatment of choice in only 13 out of 34 experienced surgeons. There is a general consensus for femoral head-conserving surgery in young patients with displaced subcapital fractures. Replacement arthroplasty was considered in the 85-year-old with a subcapital fracture. In the inexperienced group, 10 of 17 surgeons would cement the prosthesis, as would 27 of 36 in the experienced group.