Temporal Bone Landmarks of the Transversesigmoid Sinus Junction: An Anatomical Study in Dried Human Skulls

Objective: To investigate the accuracy in localization of the anterosuperior margin of TSSJ by using the intersection point between the squamosal and parietomastoid sutures (A point) and the intersection of the squamosal suture and supramastoid crest (B point) as bony landmarks.Materials and Methods: The A and B points were marked on the inner surface of a skull by using the transillumination technique. The anatomical relationship between the projected A point, B point, and groove of TSSJ was investigated in 60 dried Thai human skulls (120 sides).Results: Of the 120 sides, the projected A points were located exactly on the anterosuperior margin of the TSSJ in 38 (31.7%) instances and adjacent (above and below) the anterosuperior margin in 82 (68.3%) cases. Of the 118 sides with identifiable supramastoid crests, the projected B points were located precisely on the anterosuperior margin of TSSJ in 60 (50.8%) cases and above the anterosuperior margin of the TSSJ in 57 (48.3%) cases. Hence, the projected B point was a more reliable bony landmark for localizing the anterosuperior margin of the TSSJ when compared with the projected A point (p = 0.003, OR 2.2, and 95% CI =1.3-3.8).Conclusion: The B point is a more reliable temporal bone landmark for localization of the TSSJ than the A point. In temporal craniotomy, an initial burr hole at the B point is relatively safe and carries a very low risk of inadvertent venous sinus injury.

EXTERNAL AUDITORY MEATUS: LANDMARK FOR V OSETOTOMIES IN SQUARE FACE CORRECTION: A TECHNICAL NOTE

The authors present a new technique for planning of V-osteotomies in correction of square face. A static bony landmark: External acoustic meatus (EAM) is used for planning the osteotomy cuts on stereolithographic model which provides accurate replication of planned osteotomy cuts on table.

Utility of Caudal Angulation for Venous Access under Fluoroscopic Guidance during Cardiovascular Implantable Electronic Device Implantation

<b><i>Background:</i></b> Axillary venous access is preferred for CIED implantation. The procedure is usually performed under fluoroscopic guidance in anteroposterior (A-P) view. However, there is a lack of perception of depth in this view with a fear of creating complications. Caudal fluoroscopy (adding 30°–35° caudal angulation to A-P projection) has been proposed to circumvent this problem. <b><i>Objective:</i></b> The aim of this study was to elucidate the advantages of caudal fluoroscopy using fluoroscopic images, contrast venograms, and CT angiography images of axillary vein. <b><i>Methods:</i></b> The fluoroscopic images and contrast venograms obtained in the A-P view were compared with caudal fluoroscopy in patients undergoing CIED implantation at our centre. Also, the CT angiography images of axillary vein were reconstructed to understand the relative anatomy of the vein and the underlying lung parenchyma, simulating these 2 projections. <b><i>Results:</i></b> The CT angiography images, contrast venograms, and fluoroscopic images confirmed that caudal fluoroscopy allows better visualization of the vein in relation to the lung parenchyma and rib cage. Analysis of fluoroscopic images revealed that the bend of the first rib formed a conical prominence in caudal fluoroscopy. This served as an important bony landmark for successful venous access, which was usually obtained while the needle was being directed towards this prominence in caudal fluoroscopy. <b><i>Conclusions:</i></b> The proposed advantages of caudal fluoroscopy for CIED implantation have been elucidated by analysis of CT angiography images, contrast venograms, and fluoroscopic images.

Bilateral congenital hypertropic strabismus fixus: A case report

Purpose: To report an unusual and rare case of both eyes fixed in an extreme superomedial position. Case report: A case of 48-year-old woman presented with both eyes fixed in an extreme superomedial position; the microcorneas were covered almost completely by the upper eyelids even when she opened her eyes. A forced duction test was performed to confirm there were severe restrictions in all directions. She underwent disinsertion of the superior and medial rectus muscle, inferior oblique muscle belly transposition and sclera fixation. At the 1-year follow-up, there was improved ocular alignment. Conclusion: This case may be a special form of myopic strabismus fixus. The infratemporal fossa may be a bony landmark related to the etiology of global fixation.

Establishing a New Bony Landmark for Safe Screw Insertion in Medial Displacement Calcaneal Osteotomy: A Simulation-Based Approach

Category: Hindfoot; Other Introduction/Purpose: Medial displacement calcaneal osteotomy (MDCO) is a commonly performed procedure in flatfoot reconstruction. Fixation is often achieved with screws due to its ability to compress across the osteotomy site. Screws are placed via a free-handed technique without direct fluoroscopic visualization, due to difficulty attaining a simultaneous axial calcaneal view. In addition, the posterior calcaneal tuber translates medially after displacement, resulting in altered anatomical geometry. It is therefore important to establish a reliable external bony landmark when performing free-handed interfragmentary fixation in order to avoid potential screw-related complications and to provide better surgical technique and fixation. The purposes of this study are to validate a new external bony landmark and to establish the appropriate trajectory and screw length for free-hand screw fixation in MDCO. Methods: A total of 84 postoperative computed tomography (CT) scans of MDCO in 70 patients were analyzed. The images were reconstructed using a 3-dimensional simulation program (Vworks 4.0, Cybermed). Virtual screw insertion was simulated by aiming towards two bony landmarks: the base of the 5th metatarsal in the axial plane, and the sinus tarsi in the sagittal plane (Figure 1). A grading system was also utilized to classify scenarios in which the screw breached the distal cortical wall: Grade 1 was defined as contact between the virtual screw and the cortex, Grade 2 as the screw approaching the outer margin of the cortex, and Grade 3 as the screw penetrating the outer cortex. The trajectory angle between the screw and the osteotomy, as well as the screw size, were also measured. Results: The average age of patients was 24.5 (range, 19 to 53), and 100% were males. The average displacement of the posterior calcaneal fragment was 7.3+-1.5 mm (range, 3.9 to 13.8). Among the 84 virtual screws, only five (6.0%) breached the medial cortical wall of the osteotomized calcaneus. All medial breaches were Grade 1. None of the virtual screws breached the lateral cortical wall. Mean trajectory angle between the virtual screw and the osteotomy site was 74.9+-6.7˚ (range, 60.0 to 89.8˚). In the perioperative data, estimated maximum screw length by simulation was 55.6+-4.4 mm (range, 50 to 65). Conclusion: Our results suggest that the optimal trajectory of free-handed screw placement can be determined through simulation of calcaneal interfragmentary screw insertion using postoperative CT imaging. Using this simulation technology, we determined a trajectory towards the sinus tarsi on the sagittal plane and the base of the 5th metatarsal on the axial plane to be a reliable external bony landmark for placement of screws in MDCO. These promising results have potential implications in achieving better fixation as well as improving union rates and operative outcomes.

A study to evaluate the adequacy of pelvic lymph node coverage in carcinoma cervix patients in Indian population by conventional four field box technique using computerized tomography simulation based pelvic lymph node contouring

Background: Traditionally pelvic External Beam Radiotherapy is delivered with four field box technique in carcinoma cervix patients. The primary aim of this prospective observational study is to determine the adequacy of pelvic lymph nodal coverage by conventional Four Field Box Technique with the help of pelvic lymph node contouring by CT simulation.Methods: Between January 2013 and August 2015 sixty patients with biopsy proven Carcinoma Cervix were enrolled in this study. Of these fifty-three patients were available for final analysis. CT simulation based Pelvic lymph node contouring was done for each patient. Then two External Beam Radiotherapy plans were generated, one contoured based and the other based on bony landmark based Four Field Box Technique. The number of patients whose contoured lymph nodes lies partly outside the field borders of the bony landmark-based plan and also its extent was determined. D90 of various groups of pelvic lymph nodes obtained from both the plans were compared using ‘paired sample t - test’.Results: It was seen that with Four Field Box Technique there is inadequate coverage of common iliac lymph nodes in 34/53 patients. The difference between the mean D90 of common iliac lymph nodes in two sets of plans was found to be statistically significant.Conclusions: Pelvic field planning should be individualized. CT simulation-based radiotherapy planning should be done for each individual patient to adequately cover the nodal microscopic disease.

Nutrient Foramen of Fibula in Relation to Distal end, Potential Implications for Vascularised Done Graft Surgery

Background Free vascularised fibular bone grafting has gained popularity in various Orthopaedic and Oral & maxillofacial reconstructive surgeries. The objective of the present study was to identify the morphology and topography of nutrient foramina of fibula and to determine the foraminal index (FI) of the fibula using a more surgeon friendly bony landmark. Methods The study comprised examination of 100 fibulae specimens. Each bone was divided into 03 parts and topographical analysis was performed on each section. The nutrient foramina were identified macroscopically using size 24-gauge needle. Modified Hughes formula was used to calculate the foraminal index using distance of foramen (DF) from distal end which is easier to palpate in living human beings, total length of fibula (TL); and the formula was DF/TL x100. Results With respect to fibulae, 98% had single foramen and foramen was absent in 2%. The mean foraminal index (FI) was 56% for fibulae using modified Hughes’ formula. The majority of the fibulae showed nutrient foramen in the middle 3rd in relation to distal end of fibula. Conclusion The study provides information on the morphology of nutrient foramina in relation to easily palpable landmark on living human beings, which can provide guidance to surgeon while performing microvascular bone transfer procedures.