Reliable Landmark Research Articles

Technique of accurate humeral length restoration for hemiarthroplasty of the shoulder in proximal hummers fractures

Proper humeral height is key to success in shoulder hemiarthroplasty in comminuted fractures of proximal humerus. Restoring it in a precise way results in excellent functional outcome. Pectoralis major tendon serve as a reliable landmark for this purpose. Preoperative templating by Gothic Arch technique was almost comparable to intraoperative measurement using pectoralis major tendon as reference. Purpose of this study was to evaluate the accuracy of the surgical technique using pectoralis major tendon as reference for restoration of humeral length.

The fibular shaft axis and medial cortex of the proximal fibula are reliable landmarks for the mechanical axis of the tibia in patients with knee osteoarthritis

BackgroundThis study aimed to evaluate the validity of proximal fibular anatomic landmarks for measuring the coronal tibial mechanical axis in patients with knee osteoarthritis and to investigate individual factors associated with their reliability. MethodsA total of 106 knees in 96 patients were retrospectively reviewed. The angles between the tibial mechanical axis and fibular shaft axis (TFA), medial cortex of the proximal fibular shaft (MTA), and lateral cortex of the proximal fibular shaft (LTA) were measured from full-leg standing digital anteroposterior radiographs. An angle within three degrees was considered reliable. The association between the above three angles and individual factors, such as age, sex, body mass index (BMI), and varus–valgus knee malalignment, was determined to investigate individual factors associated with their reliability. ResultsThe median TFA, MTA, and LTA were 1.52°, 1.56°, and 2.62°, respectively. The reliability rates of TFA, MTA, and LTA were 73.6% (95% CI: 65.19–81.98%), 82.1% (74.77–89.38%), and 58.5% (49.11–67.87%), respectively. The reliability of TFA and MTA was not associated with individual variables. The reliability of LTA was associated with BMI. Among patients with BMI greater than 25.3 kg/m2, LTA was considered reliable in 65.7%; this rate was significantly higher than that among patients with BMI less than 25.3 kg/m2. ConclusionsThe fibular shaft axis and medial cortex of the proximal fibular shaft are reliable landmarks of the mechanical axis of the tibia. However, the reliability of the lateral cortex of the proximal fibular shaft is less satisfactory, especially in patients with BMI less than 25.3 kg/m2.

A White Matter Fiber Microdissection Study of the Anterior Perforated Substance and the Basal Forebrain: A Gateway to the Basal Ganglia?

Studies detailing the anatomy of the basal forebrain (BF) from a neurosurgical perspective are missing. To describe the anatomy of the BF and of the anterior perforated substance (APS), the BF emphasizing surgical useful anatomical relationship between surface landmarks and deep structures. White matter fiber microdissection was performed on 5 brain specimens to analyze the topographic anatomy of the APS and expose layer-by-layer fiber tracts and nuclei of the BF. The APS, as identified anatomically, surgically, and neuroradiologically, has clear borders measured 23.3 ±3.4 mm (19-27) in the mediolateral and 12.5±1.2 mm (11-14) in the anteroposterior directions. A detailed stratigraphy of the BF was performed from the APS up to basal ganglia and thalamus allowing identification and dissection of the main components of the BF (septum, nucleus accumbens, amygdala, innominate substance) and its white matter tracts (band of Broca, extracapsular thalamic peduncle, ventral amygdalohypothalamic fibers). The olfactory trigone together with diagonal gyrus and the APS proper is a relevant superficial landmark for the basal ganglia (inferior to the nucleus accumbens, lateral to the caudate head, and medial to the lentiform nucleus). The findings in our study supplement available anatomic knowledge of APS and BF, providing reliable landmarks for precise topographic diagnosis of BF lesions and for intraoperative orientation. Surgically relevant relationships between surface and deep anatomic structures are highlighted offering thus a contribution to neurosurgeons willing to perform surgery in this delicate area.

The Distance between the Pylorus and Left Vagus Nerve during Sleeve Gastrectomy.

The sleeve gastrectomy (SG) can be performed with or without antral preservation (distance from the pylorus <50 mm). The objective of this study was to evaluate the distance between the pylorus and the end of the left vagus nerve in order to determine whether it could be used as a constant anatomical landmark to start gastric transection. This was a prospective, nonrandomized study of 120 patients undergoing SG from January to October 2018. The distance measurement between pylorus and vagus nerve was performed at the beginning of the SG. The primary endpoint was the distance between the beginning of the pylorus and the end of the second branch of the vagus nerve on the upper edge of the antrum. The secondary endpoints was the correlation factors between the preoperative data and the position of the end of the vagus nerve. A total of 120 patients, with a mean body mass index of 42.2 kg/m2 , underwent primary SG. The mean distance between pylorus and the end of the vagus nerve was 50.4 mm (35-64) on the upper part of the antrum. When considering the inferior part of the antrum, the minimum distance was 50 mm. No correlations were found between preoperative data and distance measurements. The vagus nerve can be considered as a constant and reliable anatomical landmark for performing SG with antral preservation. However, no correlation was found between the preoperative data and the location of the end of the vagus nerve. Clin. Anat. 33:562-566, 2020. © 2019 Wiley Periodicals, Inc.

Accuracy and Safety of Lateral Vertebral Notch-Referred Technique Used in Subaxial Cervical Pedicle Screw Placement.

Biomechanical studies revealed that pedicle screw instrumentation has a superior stabilizing effect compared with other internal fixations in reconstructing the subaxial cervical spine. However, severe neurovascular risks preclude surgeons from routinely conducting pedicle screw manipulation in cervical spine. To evaluate the accuracy and safety of the lateral vertebral notch (LVN)-referred technique used in subaxial cervical pedicle screw (CPS) placement. One hundred thirty-five consecutive retrospective patients with cervical disorders underwent the LVN-referred technique for CPS placements in 3 spine centers. Postoperative pedicle perforations were confirmed by CT scans to assess the technical accuracy. Neurovascular complications derived from CPS misplacements were recorded to evaluate the technical safety. A total of 718 CPSs were inserted into subaxial cervical spine. Postoperative CT scans revealed that the accuracy of CPS placement was superior. Neither vertebral artery injury nor spinal cord injury occurred. One radiculopathy was from a unilateral C6 nerve root compression. A screw-related neurovascular injury rate of 0.7% occurred in this cohort. Additionally, there was no significant difference in the accuracy of CPS placement among 3 surgeons (H=1.460, P=.482). The relative standard deviation values revealed that technical reproducibility was acceptable. Furthermore, there was no significant difference between the patients' pedicle transverse angles and inserted CPS transverse angles from C3 to C7 (all P>.05). The LVN is a reliable and consistent anatomic landmark for CPS placement. The accuracy and safety of subaxial CPS placement by using LVN-referred technique are highly acceptable, which may endow this technique to be practicably performed in selected patients.

Optico-carotid recess and anterior clinoid process pneumatization â€" proposal for a novel classiï¬cation and uniï¬ed terminology: an anatomic and radiologic study.

The aims of this study were to propose a novel and uniï¬ed classiï¬cation system of the optico-carotid recess (OCR) and anterior clinoid process (ACP) pneumatization, determine their frequency in a Caucasian population and measure the size of the OCR. A total of 200 specimen (400 sphenoid sinuses) were evaluated in a separate anatomic cadaveric study (n=100) and radiologic study (n=100) by using sphenoidal sinus cast and computed tomography (CT) scan. OCR was divided according to its location to the optic nerve into sub-optical and latero-optical OCR grade I-III. An OCR was found in 39% of the samples (78/200) and in 19% (38/200) it occurred bilaterally. Both, sub-optical and latero-optical OCR were identiï¬ed in 14% of the sides (58/400), with a mean length and depth of 6.9 mm; 7.7 mm and 2.3 mm, 7.1 mm, respectively. We determined the pneumatized ACP frequency with 23% (46/200) and deï¬ned 3 uniï¬ed different types of pneumatization. The OCR is a reliable landmark to identify the optico-carotid region in endoscopic sphenoid sinus surgery, and can even be visualized by CT. Hence, preoperative investigation of the sphenoid region is mandatory. In our opinion, the classiï¬cation presented in this study can be useful in order to avoid surgical complications.

Herald Cell: The Gateway to Posterior Tympanotomy-A Cadaveric Study.

Posterior tympanotomy is the avenue to the facial recess of the middle ear from mastoid antrum. The entry into the facial recess in many cases is heralded by a distinct air cell before approaching the facial-chordal plane. The current study was undertaken to determine the prevalence of this 'Herald Cell' in an adult cadaveric population. It was a human cadaveric temporal bone dissection study. The bones were dissected to carry out cortical mastoidectomy and posterior tympanotomy using standard otologic drills under microscopic visualization (Leica M320 F12). Appropriate snapshots were taken to document the presence or absence of Herald cell. A total of 51 temporal bones were dissected (26 right, 25 left sided). The Herald cell was found to be present in 22 bones (43.1%). Herald cell, when present, is a convenient and reliable landmark to carry out a safe posterior tympanotomy.

The Distance between the Pectoralis Major Tendon Insertion and the Top of the Humeral Head is a Reliable Landmark: An Anatomic Study.

Purpose This study aimed to analyze the distance between the superior edge of the pectoralis major and the top of the humeral head and evaluate whether this distance is a consistent measurement. Methods Twenty-two shoulders in eleven cadavers were dissected and the attachment of the pectoralis major tendon was preserved. Two distances were recorded with the help of digital vernier caliper: the distance between the upper edge of pectoralis major and tangent to the top of humeral head (PM–T) and the distance between the superomedial tip of greater tuberosity (GT) and the upper edge of the pectoralis major tendon (PM–G; ± standard error of the means). Results The mean PM–T distance was 53.8 mm (±0.8 mm) and the mean PM–G distance was 46.8 mm (±0.9 mm). The distance between the top of humeral head and tip of the GT was 7 mm. The PM–T distance was a significant outlier in three shoulders as it inserted high on the humerus. Conclusion We can conclude that the PM–T and PM–G distances were a consistent measurement. Clinical Relevance The distance between the pectoralis major tendon and top of the humeral head was measured in this study as a reliable method that can be used intraoperatively to decide the height of the humerus prosthesis in comminuted fractures of the proximal humerus.

Use of Anatomical Landmarks in Ankle Arthroscopy to Determine Accuracy of Syndesmotic Reduction: A Cadaveric Study.

Background. The aim of this study was to determine the accuracy of ankle arthroscopy as a means for diagnosing syndesmotic reduction or malreduction and to determine anatomical landmarks for diagnosis. Methods. Six matched-pair cadavers (n = 12) with through-knee amputations were studied. Component parts of the syndesmosis and distal 10 cm of the interosseous membrane (IOM) were sectioned in each. The 12 specimens were divided into 2 groups: 6 specimens in the in-situ group fixed with suture button technique and 6 specimens in the malreduced group rigidly held with a 3.5-mm screw. Specimens were randomized to undergo diagnostic arthroscopy by 3 fellowship-trained foot and ankle orthopaedic surgeons in a blinded fashion. Surgeons were asked to determine if the syndesmosis was reduced or malreduced and provide arthroscopic measurements of their findings. Results. Of 36 arthroscopic evaluations, 34 (94%) were correctly diagnosed. Arthroscopic measurement of 3.5 mm diastasis or greater at the anterior aspect of the distal tibiofibular syndesmosis correlated with a posteriorly malreduced fibula. Arthroscopic evaluation of the Anterior inferior tibiofibular ligament (AITFL), IOM, Posterior inferior tibiofibular ligament (PITFL), lateral fibular gutter, and the tibia/fibula relationship were found to be reliable landmarks in determining syndesmotic reduction. An intraclass correlation coefficient (ICC) for interrater reliability of 1.00 was determined for each of these landmarks between 2 surgeons (P < .001). The ICCs between 2 surgeons' measurements and the computed tomography measurements were found to be 0.896 (P value < .001). Conclusions. Ankle arthroscopy is a reliable method to assess syndesmotic relationship when reduced in situ or posteriorly malreduced 10 mm. Levels of Evidence: Level V: Cadaveric.

Forget the Greater Trochanter! Hip Joint Access With the 12 O’clock Portal in Hip Arthroscopy

Most surgeons rely on the greater trochanter as the reference point to establish the anterolateral portal. Nevertheless, we believe that the anterosuperior iliac spine is a more reliable landmark. Unlike the greater trochanter, it is unaffected by leg rotation and is more easily identified by palpation. Abiding by the central tenet of medicine to “do no harm,” the technique described herein presents in detail the concept of the 12 o’clock portal placement, a hip joint access method based on identifying specific anatomic points under fluoroscopy and by palpation. To accomplish this goal, this Technical Note presents a step-by-step approach, including tips and pearls for patient positioning and fluoroscopic guidance. We believe this method ensures a reproducible and safe way to start hip arthroscopy in the supine position.

Visualization of Dark Side of Skull Base with Surgical Navigation and Endoscopic Assistance: Extended Petrous Rhomboid and Rhomboid with Maxillary Nerve–Mandibular Nerve Vidian Corridor

Lesions located at the petrous apex, cavernous sinus, clivus, medial aspect of the jugular foramen, or condylar regions are still difficult to fully expose using the operating microscope. Although approaches to this region through the middle cranial fossa have been previously described, these approaches afford only limited visualization. We have confirmed a transcranial infratemporal fossa combined microsurgical and endoscopic access to the petrous apex, clivus, medial aspect of the jugular foramen, and occipital condyle. We have presented the results of a micro-anatomical cadaver dissection study and its clinical application. Ten latex-injected cadaveric specimens (20 twenty sides) underwent dissection with navigational guidance to achieve an extended anterior petrosal approach combined with a far vidian corridor approach (between the foramen rotundum and foramen ovale). We performed anatomical dissections to confirm the surgical anatomy and the feasibility and limitations of this approach. Anatomical dissections were performed in the skull base laboratory of Lariboisière Hospital and Duke University Medical Center. This approach was then applied to some clinical cases. The combination of the microscope and endoscope, aided by surgical navigation, was extremely effective and provided a wide view of the petrous rhomboid, the entire clivus, and the medial condylar regions. The extended extradural anterior petrosal approach provided a large corridor to petrous and clival lesions. Endoscopic assistance allows for wide and deep exposure of the middle to lower clivus, epipharyngeal space, and bilateral condylar regions. This approach successfully provided adequate surgical access for resection of tumors located in these regions. The depth of the medial aspect of the jugular foramen was 16.3 ± 1.2 mm deep from the geniculate ganglion. The emerging point of the inferior petrosal sinus in the jugular foramen was 16.5 ± 1.8 mm deep from the geniculate ganglion. The hypoglossal canal was 21.6 ± 2.2 mm deep from the geniculate ganglion. The foramen magnum was located 31.5 ± 2.4 mm deep from the gasserian ganglion. The inferior petrosal sinus was found to be a reliable landmark to identify the medial portion of the jugular bulb. The introduction of the endoscope through the middle fossa rhomboid enabled visualization of the medial aspect of the jugular bulb, which otherwise would be hampered by the internal auditory canal under the microscope. After microscopic exposure of the middle fossa rhomboid, neuronavigational endoscopic assistance facilitated visualization of the ventral cavernous region, petrous apex, retropharyngeal space, and middle and inferior clivus down to the medial aspect of the jugular bulb and condyle regions. Additional maxillary nerve-mandibular nerve vidian corridor visualization provides a lateral transsphenoidal approach to upper clivus lesions.

Pigmented border as a new surface landmark for digital nerve blocks: a cross sectional anatomical study.

The purpose of this study was to identify surface anatomy of digital nerves in relation to the pigmented border of digits. Three-hundred and sixty digital nerves in 36 preserved adult cadaveric hands were dissected under magnification. The digital nerves were constantly located anterior to the pigmented border. The median curvilinear distance along the skin from the pigmented border to the digital nerves of the index, middle, ring and little fingers was 1.4 mm. In the thumb, this distance was 2.4 and 3.7 mm on the radial and ulnar sides, respectively. The digital nerve was located 2.4 mm deep to the skin in all fingers. The median angle to the nerve from the skin at the pigmented border was 30°. These dimensions differed in the thumb compared with the rest of the fingers. We conclude that the pigmented border of digits is a reliable anatomical landmark to locate digital nerves.

Anatomical assessment of the digastric branch of the facial nerve as a landmark to localize the extratemporal facial nerve trunk.

Localization of the facial nerve trunk (FNT) [i.e., the portion of the facial nerve between the stylomastoid foramen (SMF) and pes anserinus] may be required during various surgical interventions such as parotidectomy and hypoglossal-facial anastomosis. Several landmarks have been proposed for efficient identification of the FNT. We sought to assess the anatomical features of the digastric branch of the facial nerve (DBFN) and its potential as a landmark to identify FNT. Fifteen sides of eight cadaveric heads were dissected to find the DBFN. Anatomic features of DBFN including its point of origin relative to SMF, length, and important relationships, as well as the distance between the insertion point on the digastric muscle and mastoid tip were recorded. DBFN was found in all specimens originating from the FNT outside the SMF with an average length (± standard deviation) of 15.4 ± 3.4mm. In all specimens, the DBFN inserted on the superomedial aspect of the posterior belly of the digastric muscle (PBD). In 8/15 specimens, DBFN was accompanied by the stylomastoid artery on its anteromedial side. Average distance (± standard deviation) between the mastoid tip and the nerve insertion point on PBD was 13.6 ± 2.0mm (range 10-17). The DBFN is a reliable landmark for identifying the FNT. It could be consistently identified within 15-20mm of the mastoid tip on the superomedial aspect of the PBD. The DBFN may be used as a supplementary landmark for efficient localization of the FNT. Not applicable (anatomic study).

Is Panoramic Imaging Equivalent to Cone-Beam Computed Tomography for Classifying Impacted Lower Third Molars?

Preoperative recognition of the relative position of the mandibular third molars may contribute to more reliable treatment planning, avoiding injuries and decreasing surgical and recovery times. The research questions for this study were as follows: 1) Is panoramic radiography (PR) equivalent to cone-beam computed tomography (CBCT) in determining the degree of mandibular third molar impaction? 2) For PR, is the external oblique ridge a more reliable reference to determine the degree of mandibular third molar impaction? This retrospective case-series study assessed whether the imaging modalities (primary predictor variable) are equivalent in determining the degree of impaction of third molars (primary outcome variable) according to the parameters of the Pell and Gregory classification. Two oral and maxillofacial radiologists evaluated PR and CBCT images presenting at least 1 mandibular third molar. The degrees of impaction related to the ascending ramus and related to the external oblique ridge (secondary outcome variables) also were assessed. The agreement rates between PR and CBCT were presented, and the imaging modalities were compared by the McNemar-Bowker test (α=.05). A total of 173 patients were included (66 male and 107 female patients). Among these patients, 313 mandibular third molars were assessed. In relation to the occlusal plane, the agreement rate between PR and CBCT was 82.1% for Pell and Gregory class A, 90.5% for class B, and 65.6% for class C (P=.116). The overall agreement rate between the classifications in relation to the mandibular ramus on PR and CBCT ranged from 66.8% (considering the ascending ramus, P<.001) to 76.4% (considering the external oblique ridge, P<.001). PR performs similarly to CBCT in the classification of impaction in relation to the occlusal plane. However, PR shows a tendency to underestimate the space for accommodation of the third molar compared with CBCT. Furthermore, the external oblique ridge is not a reliable alternative landmark on PR.

The Case of Asymmetry of the Omohyoid Muscle

The asymmetry of omohyoid muscles was found during topographic anatomical preparation of female cadaver (using methods: anatomical preparation and morphometry) which was use in medical student’s training. The detected deviations in structure of this muscle, accordingly to many articles, have not only anatomic value but also a significant importance for clinical surgeons of different fields. The described anatomical variation of omohyoid muscle structure (the asymmetry) has some very important clinical aspects, concerning front neck region surgery. Omohyoid muscle is a reliable landmark for endoscopic examination of brachial plexus and searching for metastases in neck lymphatic nodes. In some cases, hypertrophy of omohyoid muscle can cause development of functional dysphagia and spastic torticollis.

Finding the “Sweet Spot” for C2 Root Transection in C1 Lateral Mass Exposure

Atlantoaxial fusion often requires C2 nerve transection for complete C1 lateral mass exposure. Nerve transection is made ideally at the preganglionic segment proximal to the dorsal root ganglion to minimize the risk of postoperative dysesthesias. If the nerve is transected too proximally, cerebrospinal fluid leak may be encountered by violation of the dura and arachnoid where the sensory and motor nerve rootlets exit the subarachnoid space. In this study we aimed to quantify the length of the C2 nerve preganglionic segment using cadaveric specimens and develop a method for reliable intraoperative localization for sectioning during C1-2 arthrodesis. Using microsurgical techniques, 16 C2 nerves from 8 frozen and injected cadaveric cervical spine specimens were dissected. Two key measurements were taken to establish a reliable method of preganglionic segment identification. The "sweet spot" for nerve transection was based on the approximate location of the midpoint of the preganglionic segment. The final determination of the ideal spot for C2 nerve transection using these calculations was 3 mm lateral to the medial border of the lateral mass. This anatomic study found remarkable consistency in the preganglionic segment length. The medial border of the lateral mass appeared to be a consistently reliable landmark for identification of the preganglionic segment of the C2 nerve root. By using relationships between known anatomic structures intraoperatively, safety of atlantoaxial fixation can be optimized to maximize complication avoidance and satisfactory patient outcomes.

Identification and analysis of photometric points on 2D facial images: a machine learning approach in orthodontics

The lack of an effective and automated facial landmark identification tool has prompted us to design and develop a smart machine learning approach. The study aims to address two objectives. The primary objective is to assess the effectiveness and accuracy of algorithmic methodology in identifying and analysing facial landmarks on two dimensional (2D) facial images and the secondary objective is to understand the clinical application of automation in facial landmark identification. The study has utilised 418 facial landmark points and 220 landmark measures from 22 2D facial images of volunteers. The study has used a deep learning algorithm ‘You Only Look Once (YOLO)’ to determine the accuracy of the developed system and its clinical applications. The system identified 418 landmarks in total with facial recognition being 100%. Of the total 220 landmark measures, the system provided 48 (21.81%) measures in the error range of 0 to 1 mm, 75 (34.09%) measures in the error range of 2 to 3 mm, 92 (41.81%) measures in the error range of 4 to 5 mm followed by 5 (2.2%) measures in the range of 6 mm. The smart and innovative approach provides valuable training and a helpful tool for the students performing the clinical facial analysis. The automated system with its effective and efficient algorithm delivers fast and reliable landmark identification and analysis.

Reliability of 3D dental and skeletal landmarks on CBCT images.

To quantify reliability of three-dimensional skeletal landmarks and a comprehensive set of dental landmarks in cone-beam computed tomography (CBCT) and to determine the shapes of envelope of error. Three judges located 31 skeletal landmarks and 60 dental landmarks on the pre- and posttreatment CBCT images of 22 patients. Landmark error was determined by calculating the distance of deviation of landmark locations around their average. Standard deviation and mean radial spherical error were calculated. Scatterplots were constructed to characterize envelope of error. The midline landmarks of the cranial base were highly reliable. Bilateral skeletal landmarks tended to have larger error than midline landmarks. Among the nonconventional landmarks, fronto-zygomatic suture, condyle, and mental foramen showed relatively high reliability. However, foramen spinosum and temporal fossa showed larger errors. Gonion was the least reliable landmark. Most dental landmarks were located more reliably than skeletal landmarks. The highest reliability was found at incisal edges. Mesiobuccal cusp of first molars also showed high reliability. There were differences in the size and shape of the distributions of errors of different landmarks. Most landmarks showed elongated envelopes. Bilateral structures tended to show greater errors than midline structures. Most dental landmarks were more reliable than skeletal landmarks.

Consistency of the lateral canthus as an anatomic landmark and its clinical implications.

Successful oculofacial procedures require the availability of a reliable surgical and anatomic landmark. This study aimed to determine the usefulness of the lateral canthus as a surface landmark. Seventy-seven from 42 Korean cadavers were dissected. The horizontal distance from the lateral canthus to the lateral orbital margin and the vertical distances from the zygomaticofrontal suture and the inferior orbital margin to the lateral canthus were measured. The mean horizontal distance from the lateral canthus to the lateral orbital margin was 7.8 mm. Although the horizontal position of the lateral canthus appears to alter with age, the variation was only 2-3 mm. The mean vertical distances from the zygomaticofrontal suture and inferior orbital margin to the lateral canthus were 8.1 and 17.2 mm. The vertical position of the lateral canthus did not vary with age, being located inferiorly within a fingernail width from the zygomaticofrontal suture. The lateral canthus, which is easily accessible and supported by muscular and fibrous lateral orbital attachments, exhibits small anatomic variations. Thus, the lateral canthus could act as a reliable surface landmark for identifying the location of underlying structures and describing a lesion on the face. Clin. Anat. 32:630-634, 2019. © 2019 Wiley Periodicals, Inc.

Is the Supraorbital Notch a Reliable Landmark to Avoid the Frontal Sinus?

When performing a craniotomy involving the orbital bar, the supraorbital notch is a potential landmark to localize the lateral extent of the frontal sinus. Avoidance of the frontal sinus is important to reduce the risk of postoperative surgical site infection, epidural abscess formation, and mucocele development. To determine the reliability of the supraorbital notch as a marker of the lateral location of the frontal sinus. Cadaveric dissections were used with image guidance software to define the relationship between the frontal sinus and supraorbital foramen. The supraorbital notch was located 2.54 cm from midline and the lateral extent of the frontal sinus extended 2.84 mm lateral to the supraorbital notch. When performing a craniotomy extending medially to the supraorbital notch at a perpendicular angle, the frontal sinus was breached in 65% of craniotomies. When the craniotomy ended 10 mm lateral to the supraorbital notch, the rate of frontal sinus breach decreased to 10%. When performing a craniotomy involving the supraorbital notch, a lateral to medial trajectory that ends 15 mm to the supraorbital notch will minimize the risk of frontal sinus violation.