Minimal Detectable Bone Fracture Gaps in CT Images and Digital Three-Dimensional (3D) Radii Models.

Knowledge of the minimal detectable bone fracture gap is essential in three-dimensional (3D) models, particularly in pre-operative planning of osteosynthesis to avoid overlooking gaps. In this study, defined incisions and bony displacements ranging from 100 to 400 µm were created in diaphyseal radii in 20 paired forearm specimens and verified with light microscopy. The specimens were scanned utilizing different computed tomography (CT) technologies/scanners, specimen positionings, scan protocols, image segmentations, and processing protocols. Inter- and intra-operator variabilities were reported as coefficient kappa. In CT images, fracture gaps of 100 µm and bone lamellae of 300 µm and 400 µm width were identified at a rate of 80 to 100%, respectively, independent of the investigated settings. In contrast, only 400µm incisions and bony displacements were visible in digital 3D models, with detection rates dependent on CT technology, image segmentation, and post-processing algorithm. 3D bone models based on state-of-the-art CT imaging can reliably visualize clinically relevant bone fracture gap sizes. However, verification of fractures to be surgically addressed should be verified with the original CT image series.

Endoscopic-assisted transorbital extended orbital exenteration: A multi-institutional preclinical study.

BACKGROUND: Sinonasal malignancies with orbital invasion have dismal prognosis even when treated with orbital exenteration (OE). Sugawara et al. developed a surgical strategy called "extended-OE (EOE)," showing encouraging outcomes. We hypothesized that a similar resection is achievable under endoscopic guidance through the exenterated orbit (endoscopic-EOE). METHODS: The study was conducted in three institutions: University of Vienna; Mayo Clinic; University of Insubria; 48 orbital dissections were performed. A questionnaire was developed to evaluate feasibility and safety of each step, scoring from 1 to 10, ("impossible" to "easy," and "high risk" to "low risk," respectively), most likely complication(s) were hypothesized. RESULTS: The step-by-step technique is thoroughly described. The questionnaire was answered by 25 anterior skull base surgeons from six countries. Mean, median, range, and interquartile range of both feasibility and safety scores are reported. CONCLUSIONS: Endoscopic-EOE is a challenging but feasible procedure. Clinical validation is required to assess real-life outcomes.

First standardized assessment of perforators and perforasomes of the occipital artery - An anatomical study.

BACKGROUND: Flaps have become an integral part of plastic and reconstructive surgery. The robust blood supply of such flaps is a prerequisite to reduce flap failure. Despite the reported versatility of the occipital flap, comprehensive anatomical studies on its perforators and perforasomes are lacking. Hence, we examined the perforators originating from the occipital artery and their associated perforasomes, aiming to fill this knowledge gap for reconstructive surgery techniques. METHODS: 39 of 40 occipital arteries of 20 fresh anatomical head specimens were dissected. Perforators with a least an outer diameter of 0.50 mm were identified and injected with dye to color their respective perforasomes. Location and size of the colored skin areas were determined as well as the location of their perforators were documented and analyzed. RESULTS: In total, 183 perforators were found and described. The mean diameter of these vessels was 0.88 ± 0.27 mm (0.5-2.1 mm). The mean area of the perforasomes was 1288.26 ± 662.51 mm2 (144.60-3890.60 mm2). They were localized over the whole nuchal and occipital area. Lastly, perforator diameters were significantly associated with the size of their resulting perforasomes. CONCLUSION: This study is the first comprehensive overview of perforators and associated perforasomes of the occipital artery on a respectable amount of specimen. The arterial supply of big portions of the occipital and nuchal area is provided solely by the perforators of the occipital artery. For flap surgery, perforator diameter is a crucial detail to be considered in the decision-making process.

Accuracy Analysis of 3D Bone Fracture Models: Effects of Computed Tomography (CT) Imaging and Image Segmentation.

The introduction of three-dimensional (3D) printed anatomical models has garnered interest in pre-operative planning, especially in orthopedic and trauma surgery. Identifying potential error sources and quantifying their effect on the model dimensional accuracy are crucial for the applicability and reliability of such models. In this study, twenty radii were extracted from anatomic forearm specimens and subjected to osteotomy to simulate a defined fracture of the distal radius (Colles' fracture). Various factors, including two different computed tomography (CT) technologies (energy-integrating detector (EID) and photon-counting detector (PCD)), four different CT scanners, two scan protocols (i.e., routine and high dosage), two different scan orientations, as well as two segmentation algorithms were considered to determine their effect on 3D model accuracy. Ground truth was established using 3D reconstructions of surface scans of the physical specimens. Results indicated that all investigated variables significantly impacted the 3D model accuracy (p < 0.001). However, the mean absolute deviation fell within the range of 0.03 ± 0.20 to 0.32 ± 0.23 mm, well below the 0.5 mm threshold necessary for pre-operative planning. Intra- and inter-operator variability demonstrated fair to excellent agreement for 3D model accuracy, with an intra-class correlation (ICC) of 0.43 to 0.92. This systematic investigation displayed dimensional deviations in the magnitude of sub-voxel imaging resolution for all variables. Major pitfalls included missed or overestimated bone regions during the segmentation process, necessitating additional manual editing of 3D models. In conclusion, this study demonstrates that 3D bone fracture models can be obtained with clinical routine scanners and scan protocols, utilizing a simple global segmentation threshold, thereby providing an accurate and reliable tool for pre-operative planning.

Three-Dimensional Osseointegration Patterns of Cementless Femoral Stems: An ex Vivo Study with High-Resolution Imaging and Histological Evaluation.

BACKGROUND: Osseointegration is essential for the long-term survival of cementless femoral stems and is dependent on periprosthetic bone quality and correct implantation technique. The aim of this study was to evaluate the 3-dimensional long-term fixation patterns of, and bone microarchitecture around, cementless hip stems. METHODS: Four specimens with varying degrees of bone quality and fixation characteristics from body donors who had received Alloclassic Zweymüller hip stems during their lifetime (mean time in situ at the time of death: 12.73 years) were evaluated with use of radiographs, high-resolution computed tomography (CT) scans, and hard-tissue histology. The CT voxel size was 85 µm, and the following parameters were calculated: total bone volume, total bone volume fraction, trabecular bone volume, trabecular bone volume fraction, cortical bone volume, cortical bone volume fraction, and cortical thickness. Bone-implant contact and canal fill index values for each Gruen zone of the specimens were calculated with use of histological samples. RESULTS: Femoral stems with apparently good cortical contact on clinical radiographs showed higher values for cortical bone volume, trabecular bone volume, and cortical thickness in the high-resolution CT analysis than femoral stems with apparently weak cortical contact on clinical radiographs. Based on the histological evaluation, the mean bone-implant contact ranged from 22.94% to 57.24% and the mean canal fill index ranged from 52.33% to 69.67% among the specimens. CONCLUSIONS: This study demonstrated different osseointegration patterns of cementless femoral stems on the basis of radiographs, high-resolution CT scans, and histological evaluation. Femora with high cortical bone volume and cortical thickness were associated with higher canal fill indices, whereas femora with low cortical bone volume and cortical thickness had lower canal fill indices and showed a characteristic corner-anchorage pattern. CLINICAL RELEVANCE: Osseointegration patterns and thus the long-term survival of cementless femoral stems are dependent on cortical bone volume and cortical thickness.

Dimensional accuracy and precision and surgeon perception of additively manufactured bone models: effect of manufacturing technology and part orientation.

BACKGROUND: Additively manufactured (AM) anatomical bone models are primarily utilized for training and preoperative planning purposes. As such, they must meet stringent requirements, with dimensional accuracy being of utmost importance. This study aimed to evaluate the precision and accuracy of anatomical bone models manufactured using three different AM technologies: digital light processing (DLP), fused deposition modeling (FDM), and PolyJetting (PJ), built in three different part orientations. Additionally, the study sought to assess surgeons' perceptions of how well these models mimic real bones in simulated osteosynthesis. METHODS: Computer-aided design (CAD) models of six human radii were generated from computed tomography (CT) imaging data. Anatomical models were then manufactured using the three aforementioned technologies and in three different part orientations. The surfaces of all models were 3D-scanned and compared with the original CAD models. Furthermore, an anatomical model of a proximal femur including a metastatic lesion was manufactured using the three technologies, followed by (mock) osteosynthesis performed by six surgeons on each type of model. The surgeons' perceptions of the quality and haptic properties of each model were assessed using a questionnaire. RESULTS: The mean dimensional deviations from the original CAD model ranged between 0.00 and 0.13 mm with maximal inaccuracies < 1 mm for all models. In surgical simulation, PJ models achieved the highest total score on a 5-point Likert scale ranging from 1 to 5 (with 1 and 5 representing the lowest and highest level of agreement, respectively), (3.74 ± 0.99) in the surgeons' perception assessment, followed by DLP (3.41 ± 0.99) and FDM (2.43 ± 1.02). Notably, FDM was perceived as unsuitable for surgical simulation, as the material melted during drilling and sawing. CONCLUSIONS: In conclusion, the choice of technology and part orientation significantly influenced the accuracy and precision of additively manufactured bone models. However, all anatomical models showed satisfying accuracies and precisions, independent of the AM technology or part orientation. The anatomical and functional performance of FDM models was rated by surgeons as poor.

Hotspots of facial artery perforators and perforasomes for easier flap guidance: An anatomical study.

BACKGROUND: The facial artery perforator flap is a valuable alternative for reconstruction of small to medium defects in the central midface and provide pleasing cosmetic results, allowing reconstruction in a one-stage procedure. Since Doppler ultrasound is not applicable to distinguish perforator from source artery, anatomical studies are needed to identify perforator areas along the course of the facial artery. METHODS: Twenty facial arteries of 10 fresh anatomical head specimens were dissected. All perforators with an outer diameter of at least 0.50 mm were identified and injected with dye to color their respective vascular territories. Size and location of colored skin territories as well as the location of its perforators were documented and statistically analyzed. RESULTS: In total, 89 perforators were identified. The average number of perforators per facial artery was 4.45±1.15. The mean outer diameter of the perforator at the origin of the facial artery was 0,65±0.14 mm. The mean size of the colored skin territories was 577.57±488.81 mm2. Perforator diameters were significantly associated with the size of its resulting perforasomes. Furthermore, perforators mostly originated in two specific areas: 3.5 cm lateral and caudal and 4.5 cm lateral and 5.5 cm caudal of the anterior nasal spine. CONCLUSION: This study provides evidence of two predominant locations of emergence of facial artery perforators. Additionally, the significant correlation between perforator size and its appendant perforasomes as well as their location with reference to the anterior nasal spine as relevant osseous landmarks helps surgeons in decision making for flap design and surgery.

Sensory Innervation of the Upper Eyelid and Its Implication for Upper Eyelid Surgery.

PURPOSE: Sensory alterations of the upper eyelid skin and eyelashes are frequently encountered after upper eyelid surgery. The objective of this study was to provide information on the exact course and distribution of sensory nerve fibers through the anatomic planes in the upper eyelid. METHODS: Ten formalin-fixed hemifaces were dissected. The nerve branches of the ophthalmic nerve in the upper eyelid were traced in an anterograde fashion. RESULTS: A total of 151 nerve fibers were recorded during dissection. The infratrochlear, supratrochlear, supraorbital, and lacrimal nerve contributed each to both the upper eyelid skin innervation and the upper eyelid rim plexus in different distribution patterns. The mean distance from the eyelid margin at which nerve fibers pierced from preseptal into the orbicularis muscle was 14 ± 1.1 mm for nerve fibers targeting the eyelid dermis and 3.7 ± 1.2 mm for nerve fibers targeting the eyelid rim plexus ( p < 0.001). The mean intraorbicular course of nerve fibers was 3 mm (0-17; standard deviation 4.1). The mean distance from the eyelid margin at which nerve fibers pierced from the orbicularis muscle into the preorbicular plane was 10 ± 1 mm for nerve fibers innervating the eyelid dermis and 1.3 ± 0.8 mm for nerve fibers innervating the eyelid rim plexus ( p < 0.001). The mean distance of the preorbicular course of nerve fibers was 2 mm (0-15; standard deviation 3.6). CONCLUSIONS: Based on the findings, a certain degree of postoperative eyelid skin numbness is inevitable while eyelash innervation may be spared in upper blepharoplasty.

Influence of Scan Parameters of Single and Dual-Energy CT Protocols in Combination with Metal Artifact Suppression Algorithms for THA: An ex Vivo Study.

BACKGROUND: Metal artifacts caused by hip arthroplasty stems limit the diagnostic value of computed tomography (CT) in the evaluation of periprosthetic fractures or implant loosening. The aim of this ex vivo study was to evaluate the influence of different scan parameters and metal artifact algorithms on image quality in the presence of hip stems. METHODS: Nine femoral stems, 6 uncemented and 3 cemented, that had been implanted in subjects during their lifetimes were exarticulated and investigated after death and anatomical body donation. Twelve CT protocols consisting of single-energy (SE) and single-source consecutive dual-energy (DE) scans with and without an iterative metal artifact reduction algorithm (iMAR; Siemens Healthineers) and/or monoenergetic reconstructions were compared. Streak and blooming artifacts as well as subjective image quality were evaluated for each protocol. RESULTS: Metal artifact reduction with iMAR significantly reduced the streak artifacts in all investigated protocols (p = 0.001 to 0.01). The best subjective image quality was observed for the SE protocol with a tin filter and iMAR. The least streak artifacts were observed for monoenergetic reconstructions of 110, 160, and 190 keV with iMAR (standard deviation of the Hounsfield units: 151.1, 143.7, 144.4) as well as the SE protocol with a tin filter and iMAR (163.5). The smallest virtual growth was seen for the SE with a tin filter and without iMAR (4.40 mm) and the monoenergetic reconstruction of 190 keV without iMAR (4.67 mm). CONCLUSIONS: This study strongly suggests that metal artifact reduction algorithms (e.g., iMAR) should be used in clinical practice for imaging of the bone-implant interface of prostheses with either an uncemented or cemented femoral stem. Among the iMAR protocols, the SE protocol with 140 kV and a tin filter produced the best subjective image quality. Furthermore, this protocol and DE monoenergetic reconstructions of 160 and 190 keV with iMAR achieved the lowest levels of streak and blooming artifacts. LEVEL OF EVIDENCE: Diagnostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Autologous replacement of the head of the radius-proximal fibula versus second metatarsal base: an anatomic feasibility study.

INTRODUCTION: This study investigated the anatomic feasibility of a new surgical therapy option for radial head arthrosis using an autologous vascularized bone graft of the second metatarsal and proximal fibula to recreate the proximal radiohumeral joint. MATERIALS AND METHODS: Upper and lower extremities of eleven body donors were evaluated using CT prior to anatomic dissection. Several distinct anatomic parameters were measured on the ipsi- and contralateral radial and fibular head and the second metatarsal base: bone diameter, articular surface diameter, head height, metaphyseal (neck) diameter, articular surface radius, total articular surface area, and angulation of the articular surfaces (facet). Each dissection phase was photographed in a standardized fashion and all measurements were repeated by direct caliper-measurements. RESULTS: When comparing the proximal radius and fibula to search for anatomic similarities, similar values were found in the maximum articular surface diameter and minimum and maximum measures of the neck diameter. Comparing the proximal radius and the second metatarsal, statistically similar values were found in the maximum neck diameter performing direct measurements and CT evaluation, the maximum head diameter in CT evaluation and the articular facet angulation. CONCLUSIONS: Neither the proximal fibula nor the base of the second metatarsal are ideal bone grafts for replacement of the head of the radius. The base of the second metatarsal might be a bit more suitable as a potential donor since the angulation of the proximal articular facet is similar to that of the radius. LEVEL OF EVIDENCE: Level IV, anatomic study.

Anatomical basis of retrograde thoracic veins flow and its implications in complex thoracic wall reconstructive surgery.

PURPOSE: Internal thoracic veins are increasingly used as recipient's vessels in chest wall reconstructive surgery due to their predictable anatomy and to the possibility to make a double venous anastomosis, exploiting the retrograde flow within them. Over the years, retrograde flow had been explained by the absence of valves in internal thoracic veins, which have been found recently instead. Therefore, our aim is to analyze the retrograde flow and its relationship with valves in the internal thoracic veins. METHODS: We evaluated 32 internal thoracic veins of 16 fresh-frozen specimens with undamaged thoracic cages by dynamic analysis focused on retrograde flow assessment through a partial external circulation system obtained cannulating the subclavian veins. Gross anatomical and morphological evaluations about the presence of valves and their pattern were then made. RESULTS: Efficient, partial, and absent retrograde flow was, respectively, found in 17/30, 8/30 and ITVs and 5/30 internal thoracic veins. Following Arnez's classification, 20/32 Type I and 12/32 Type II internal thoracic veins were identified. Valves were observed in 10/16 specimens (62.50%) corresponding to 36.67% of examined veins (11/30). Three valves were found between the 2nd intercostal space and 12 valves in the 3rd intercostal space. 13/15 valves were bicuspid, 2/15 tricuspid. A significant correlation (p < 0.001) between the retrograde flow and the presence of valves in internal thoracic veins was observed. CONCLUSION: Our study suggests a possible influence of the presence and the number of valves in the efficient retrograde flow of the internal thoracic veins, suggesting that, especially for more complex cases, a preoperative or intraoperative evaluation of the chest wall drainage should be recommended.

Arthroscopic accessibility of the first metatarsophalangeal joint for osteochondral defects of the metatarsal head by two-portal technique - comparing joint distraction and plantarflexion.

BACKGROUND: Several techniques and approaches for first metatarsophalangeal (MTP1) joint arthroscopy have been reported, where joint accessibility plays a key role. This study aimed to evaluate differences in arthroscopic accessibility of the first metatarsal head (MTH1) comparing non-invasive distraction and maximum plantarflexion in a two-portal approach. METHODS: Forty fresh-frozen lower leg specimens were included and divided into a distraction group (D-group) and a plantarflexion group (PF-group). A two-portal technique (1.9 mm-30°-scope) was used for arthroscopy, maximum reach at the MTH1 was marked. Following arthroscopy, specimens were dissected and examined for iatrogenic injuries. The reached area at the chondral surface was pinned and accessibility calculated. RESULTS: Accessibility of the MTH1 was 58.03 % ± 13.64 (D-group) and 55.93 % ± 10.30 (PF-group, p = 0.51). The dorsomedial hallucal nerve was injured in one specimen (2.5 %). CONCLUSION: Maximum plantarflexion showed no difference in arthroscopic MTP1 joint accessibility compared to non-invasive distraction in a two-portal approach. During dorsomedial portal placement, the dorsomedial hallucal nerve is at risk for iatrogenic injury.

The intercondylar fossa-A narrative review.

The intercondylar fossa ("intercondylar notch," IN) is a groove at the distal end of the femur, housing important stabilizing structures: cruciate ligaments and meniscofemoral ligaments. As the risk for injury to these structures correlates with changes to the IN, exact knowledge of its morphology, possible physiological and pathological changes and different approaches for evaluating it are important. The divergent ways of assessing the IN and the corresponding measurement methods have led to various descriptions of its possible shapes. Ridges at the medial and lateral wall are considered clinically important because they can help with orientation during arthroscopy, whereas ridges at the osteochondral border could affect the risk of ligament injury. Changes related to aging and sex differences have been documented, further emphasizing the importance of individual assessment of the knee joint. Overall, it is of the utmost importance to remember the interactions between the osseous housing and the structures within.

[Babysitter nerve transfer from the thenar branch to the deep terminal branch of the ulnar nerve : An option to preserve the intrinsic hand muscles in proximal lesions of the ulnar nerve]. / "Babysitter"-Nerventransfer vom R. thenaris zum R. profundus nervi ulnaris : Eine Option zum Erhalt der intrinsischen Handmuskulatur bei hohen Läsionen des N. ulnaris.

OBJECTIVE: The objective of this surgery is to achieve early reinnervation of the intrinsic hand muscles through axons of the median nerve, preventing irreversible atrophy of the muscle tissue. The nerve transfer is achieved via a babysitter graft, which is sutured end-to-side to the donor as well as the recipient nerve. The procedure is carried out in combination with a proximal reconstruction of the ulnar nerve. INDICATIONS: High-grade lesions of the ulnar nerve without spontaneous regeneration, particularly when lesions are located proximally and/or when patients present late. CONTRAINDICATIONS: Irreversible denervation of the intrinsic muscles; weakness or palsy of the thenar branch. SURGICAL TECHNIQUE: The approach is taken through a longitudinal incision over the volar wrist. The deep branch of the ulnar nerve as well as the thenar branch of the median nerve are visualized after transection of the flexor retinaculum. An autologous graft is then placed between the two nerves, sutured to the donor (thenar branch) as well as the recipient nerve (ulnar deep branch) via an epineural window in an end-to-side manner. This facilitates timely regeneration of motor axons from the median nerve into the intrinsic muscles, thereby preventing irreversible degeneration. Through the end-to-side nerve coaptation, damage to the donor nerve is reduced to a minimum. At the same time reconstruction of the ulnar nerve is performed proximally to the lesion, facilitating original reinnervation of the intrinsic muscles at a later time. POSTOPERATIVE MANAGEMENT: Postoperatively, Penrose drains are placed and a sterile hand dressing is applied. Drain removal and dressing change are performed on the first day, suture removal after 2 weeks. Physical therapy for mobility of the joints can be started as early as 1 week after surgery. After the first signs of motor and/or sensory reinnervation, a targeted retraining of daily skills should be initiated. RESULTS: This procedure has so far been reported on three patients with high-grade ulnar nerve injury. After a follow-up duration of 6 years, each achieved muscle strength of ≥ M3, with good to excellent overall regeneration according to the modified Bishop rating scale.

Thermal Effects during Bone Preparation and Insertion of Osseointegrated Transfemoral Implants.

BACKGROUND: The preparation of bone for the insertion of an osseointegrated transfemoral implant and the insertion process are performed at very low speeds in order to avoid thermal damages to bone tissue which may potentially jeopardize implant stability. The aim of this study was to quantify the temperature increase in the femur at different sites and insertion depths, relative to the final implant position during the stepwise implantation procedure. METHODS: The procedure for installation of the osseointegrated implant was performed on 24 femoral specimens. In one specimen of each pair, the surgery was performed at the clinically practiced speed, while the speed was doubled in the contralateral specimen. Six 0.075 mm K fine gauge thermocouples (RS Components, Sorby, UK) were inserted into the specimen at a distance of 0.5 mm from the final implant surface, and six were inserted at a distance of 1.0 mm. RESULTS: Drilling caused a temperature increase of <2.5 °C and was not statistically significantly different for most drill sizes (0.002 < p < 0.845). The mean increase in temperature during thread tapping and implant insertion was <5.0 °C, whereas the speed had an effect on the temperature increase during thread tapping. CONCLUSIONS: Drilling is the most time-consuming part of the surgery. Doubling the clinically practiced speed did not generate more heat during this step, suggesting the speed and thus the time- and cost-effectiveness of the procedure could be increased. The frequent withdrawal of the instruments and removal of the bone chips is beneficial to prevent temperature peaks, especially during thread tapping.

Quantitative Anatomic Comparison of Microsurgical Transcranial, Endoscopic Endonasal, and Transorbital Approaches to the Spheno-Orbital Region.

BACKGROUND: The spheno-orbital region (SOR) is a complex anatomic area that can be accessed with different surgical approaches. OBJECTIVE: To quantitatively compare, in a preclinical setting, microsurgical transcranial approaches (MTAs), endoscopic endonasal transpterygoid approach (EEA), and endoscopic transorbital approaches (ETOAs) to the SOR. METHODS: These approaches were performed in 5 specimens: EEA, ETOAs (superior eyelid and inferolateral), anterolateral MTAs (supraorbital, minipterional, pterional, pterional-transzygomatic, and frontotemporal-orbitozygomatic), and lateral MTAs (subtemporal and subtemporal transzygomatic). All specimens underwent high-resolution computed tomography; an optic neuronavigation system with dedicated software was used to quantify working volume and exposed area for each approach. Mixed linear models with random intercepts were used for statistical analyses. RESULTS: Anterolateral MTAs offer a direct route to the greater wings (GWs) and lesser wings (LWs); only they guarantee exposure of the anterior clinoid. Lateral MTAs provide access to a large area corresponding to the GW, up to the superior orbital fissure (SOF) anteriorly and the foramen rotundum medially. ETOAs also access the GW, close to the lateral portion of SOF, but with a different angle of view as compared to lateral MTAs. Access to deep and medial structures, such as the lamina papyracea and the medial SOF, is offered only by EEA, which exposes the LW and GW only to a limited extent. CONCLUSION: This is the first study that offers a quantitative comparison of the most used approaches to SOR. A detailed knowledge of their advantages and limitations is paramount to choose the ideal one, or their combination, in the clinical setting.

The intraspinal arterial collateral network: a new anatomical basis for understanding and preventing paraplegia during aortic repair.

OBJECTIVES: The anatomical distribution pattern of epidural intraspinal arteries is not entirely understood but is likely to substantially impact maintaining perfusion during segmental artery sacrifice when treating acute and chronic thoraco-abdominal aortic diseases. We investigated the anatomical distribution pattern of intraspinal arteries. METHODS: Twenty fresh, non-embalmed cadaveric human bodies were studied. Anatomical dissection and investigation of the epidural arterial network were performed according to a standardized protocol. We used a generalized mixed linear model to test whether the presence probability for certain vessels differed between vertebrae/segments. RESULTS: There was craniocaudal continuity of all ipsilateral longitudinal connections from T1 to L5 by the anterior radicular artery. The mean [±standard deviation (SD)] number of transverse anastomoses was 9.7 ± 2.1. The presence probability of transverse anastomoses along the spine was different between vertebrae (P < 0.0001). There were 2 distribution peaks along the spine: 1 peak around T4-T6 and 1 around T11. The mean (±SD) number of thoracic and lumbar anterior radiculomedullary arteries (ARMAs) was 3.0 ± 1.1. The probability of the presence of ARMAs along the spine was different for each vertebral segment (P < 0.0001). Between ARMAs there were gaps of up to a maximum of 9 vertebrae. All Adamkiewicz arteries were located caudally to T7. The median segment of the Adamkiewicz presence was T10/11. CONCLUSIONS: The epidural collateral network shows craniocaudal continuity. The number of transverse anastomoses is high. The number of ARMAs is low, and there is considerable variation in their distribution and offspring, which is highly likely to impact perfusion during segmental artery sacrifice when treating thoraco-abdominal aortic disease.

The sellar barrier on preoperative imaging predicts intraoperative cerebrospinal fluid leak: a prospective multicenter cohort study.

BACKGROUND: The type of sellar barrier observed between a pituitary tumor and cerebrospinal fluid (CSF) on preoperative magnetic resonance imaging (MRI) may predict intraoperative CSF leak during endonasal pituitary surgery. This is the first multicentric prospective cohort trial to study the sellar barrier concept and CSF leak rate during endoscopic pituitary surgery. METHODS: This multi-center, international study enrolled patients operated for pituitary adenomas via fully endoscopic endonasal surgery over a period of 4 months. The independent variable was the subtype of sellar barrier observed on preoperative MRI (strong, mixed or weak); the dependent variable was the presence of an intraoperative CSF leak. The primary goal was to determine the association between a particular type of sellar barrier and the risk of intraoperative CSF leak. Appropriate statistical methods were then applied for data analysis. RESULTS: Over the study period, 310 patients underwent endoscopic endonasal surgery for pituitary tumor. Preoperative imaging revealed a weak sellar barrier in 73 (23.55%), a mixed sellar barrier in 75 (24.19%), and a strong sellar barrier in 162 (52.26%) patients. The overall rate of intraoperative CSF leak among all patients was 69 (22.26%). A strong sellar-type barrier was associated with significantly reduced rate of intraoperative CSF leak (RR = 0.08; 95% CI 0.03-0.19; p < 0.0001), while a weak sellar barrier associated with higher rates of CSF leak (RR = 8.54; 95% CI 5.4-13.5; p < 0.0001). CONCLUSIONS: The preoperative MRI of pituitary patients can suggest intraoperative CSF leak rates, utilizing the concept of the sellar barrier. Patients with a weak sellar barrier carry a higher risk for an intraoperative CSF leak, whereas a strong sellar barrier on MRI seems to mitigate intraoperative CSF leak. We propose that preoperatively assessment of the sellar barrier can prepare surgeons for intraoperative CSF leak repair.