Anatomical Landmarks (anatomical + landmark)

Distribution by Scientific Domains


Selected Abstracts


The Superior Petrosal Triangle as a Constant Anatomical Landmark for Subtemporal Middle Fossa Orientation,

THE LARYNGOSCOPE, Issue 8 2003
Robert Sean Miller MD
Abstract Objectives/Hypothesis Anatomical landmarks including the arcuate eminence and the superficial petrosal nerve serve as orienting landmarks for middle fossa dissection. However, because of considerable variation among patients, these landmarks are not always readily identifiable. We expand on a previously described method for identifying the head of the malleus as a constant anatomical landmark to optimize exposure when employing a middle fossa approach. Methods We completed an anatomical study using 10 preserved human cadaveric temporal bones to define the anatomical relationship among the root of the zygoma, the posterior,lateral lip of the foramen spinosum, and the bony tegmen over the head of the malleus. Subsequently, 5 fresh whole human cadaveric heads (10 temporal bones) were dissected using a surgically oriented anterior petrosectomy,middle fossa approach to evaluate the consistency of localizing the head of the malleus. Results We defined the superior petrosal triangle as a stable anatomical relationship. Our cadaveric data demonstrated that the distance from the root of the zygoma to the head of the malleus was 18.7 mm (SD = 1.7 mm) and the distance from the foramen spinosum to the head of the malleus was 19.2 mm (SD = 1.0 mm). The intersection of an arc transcribed 19 mm from the root of the zygoma and an arc transcribed 19 mm from the foramen spinosum localized the head of the malleus within 2.5 mm (SD = 2.4 mm). Conclusions The landmarks defined by the superior petrosal triangle represent a means to localize the bony tegmen over the head of the malleus. Identification of the head of the malleus as a landmark in middle fossa surgery when other landmarks are not recognizable optimizes patient safety and surgeon confidence during complex surgical procedures. [source]


Are peripheral and neuraxial blocks with ultrasound guidance more effective and safe in children?

PEDIATRIC ANESTHESIA, Issue 2 2009
KASIA RUBIN MD
Summary Background and aims:, The efficacy and safety of ultrasound guided (USG) pediatric peripheral nerve and neuraxial blocks in children have not been evaluated. In this review, we have looked at the success rate, efficacy and complications with USG peripheral nerve blocks and compared with nerve stimulation or anatomical landmark based techniques in children. Methods:, All suitable studies in MEDLINE, EMBASE Drugs and Cochrane Evidence Based Medicine Reviews: Cochrane Database of Systemic Reviews databases were identified. In addition, citation review and hand search of recent pediatric anesthesia and surgical journals were done. All three authors read all selected articles independently and a consensus was achieved. All randomized controlled trials (RCTs) comparing USG peripheral and neuraxial blocks with other techniques in children were included. Results:, Ultrasound guidance has been demonstrated to improve block characteristics in children including shorter block performance time, higher success rates, shorter onset time, longer block duration, less volume of local anesthetic agents and visibility of neuraxial structures. Conclusion:, Clinical studies in children suggest that US guidance has some advantages over more traditional nerve stimulation,based techniques for regional block. However, the advantage of US guidance on safety over traditional has not been adequately demonstrated in children except ilio-inguinal blocks. [source]


The Superior Petrosal Triangle as a Constant Anatomical Landmark for Subtemporal Middle Fossa Orientation,

THE LARYNGOSCOPE, Issue 8 2003
Robert Sean Miller MD
Abstract Objectives/Hypothesis Anatomical landmarks including the arcuate eminence and the superficial petrosal nerve serve as orienting landmarks for middle fossa dissection. However, because of considerable variation among patients, these landmarks are not always readily identifiable. We expand on a previously described method for identifying the head of the malleus as a constant anatomical landmark to optimize exposure when employing a middle fossa approach. Methods We completed an anatomical study using 10 preserved human cadaveric temporal bones to define the anatomical relationship among the root of the zygoma, the posterior,lateral lip of the foramen spinosum, and the bony tegmen over the head of the malleus. Subsequently, 5 fresh whole human cadaveric heads (10 temporal bones) were dissected using a surgically oriented anterior petrosectomy,middle fossa approach to evaluate the consistency of localizing the head of the malleus. Results We defined the superior petrosal triangle as a stable anatomical relationship. Our cadaveric data demonstrated that the distance from the root of the zygoma to the head of the malleus was 18.7 mm (SD = 1.7 mm) and the distance from the foramen spinosum to the head of the malleus was 19.2 mm (SD = 1.0 mm). The intersection of an arc transcribed 19 mm from the root of the zygoma and an arc transcribed 19 mm from the foramen spinosum localized the head of the malleus within 2.5 mm (SD = 2.4 mm). Conclusions The landmarks defined by the superior petrosal triangle represent a means to localize the bony tegmen over the head of the malleus. Identification of the head of the malleus as a landmark in middle fossa surgery when other landmarks are not recognizable optimizes patient safety and surgeon confidence during complex surgical procedures. [source]


Covariance-based subdivision of the human striatum using T1-weighted MRI

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2008
Michael X Cohen
Abstract The striatum plays a key role in many cognitive and emotional processes, and displays an intricate pattern of connectivity with cortical and subcortical structures. Invasive tracing work in rats and non-human primates demonstrates that the striatum can be segregated into subregions based on similar clustering of input and output fibers. In contrast, the human striatum is typically segregated according to local anatomical landmarks without considering natural boundaries formed by functional/anatomical networks. Here, we used non-invasive magnetic resonance (MR) imaging in young, healthy adults to define subregions of the human striatum based on volume correlations with other subcortical and cortical structures. We present three methods to delineate anatomical volumetric correlations based on gray matter content estimated from T1-weighted MR images. We observed both consistencies with and divergences from invasive tracing work in animals, suggesting that magnetic resonance imaging (MRI)-based covariance likely does not correspond to direct anatomical connections, although it might index other forms of connectivity or tissue type similarity. These novel approaches may be useful in understanding connectivity of other regions, and changes in connectivity in patient or ageing populations. [source]


The orientation and dynamics of cell division within the plane of the developing vertebrate retina

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2004
Marc S. Tibber
Abstract The orientation of a dividing cell within the plane of the tissue plays an essential role in regulating cell fate in a range of developing structures. To assess its potential role in the developing vertebrate retina we used standard confocal microscopy of fixed tissue and time-lapse confocal imaging of living tissue to examine the orientation of cell division and mitotic spindle rotation within the plane of the retinal neuroepithelium. Based on the study of three rat strains and chick, we report in contrast to recent findings that during the main phase of cell production (E18,P4 in the rat and E6,E11 in the chick) dividing cells are randomly orientated with respect to key anatomical landmarks as well as the orientation of their dividing neighbours. Results from live imaging of neonatal rat retinae support these findings and suggest that unlike the developing cortex, in which metaphase plates often rotate extensively before coming to rest in anaphase, retinal mitotic spindle rotations prior to cell division are minimal. Furthermore, the orientation of metaphase entry largely defines that which is finally adopted during anaphase. Hence, the dynamics of metaphase progression through to anaphase in the retina appear to differ markedly from the brain, and cell divisions within the plane of the tissue are randomly orientated. These results contribute to a growing body of evidence that suggests that the current paradigm with respect to asymmetric division derived from the study of invertebrates cannot be generalized to the developing vertebrate nervous system. [source]


The HUDSEN Atlas: a three-dimensional (3D) spatial framework for studying gene expression in the developing human brain

JOURNAL OF ANATOMY, Issue 4 2010
Janet Kerwin
Abstract We are developing a three-dimensional (3D) atlas of the human embryonic brain using anatomical landmarks and gene expression data to define major subdivisions through 12 stages of development [Carnegie Stages (CS) 12,23; approximately 26,56 days post conception (dpc)]. Virtual 3D anatomical models are generated from intact specimens using optical projection tomography (OPT). Using mapaint software, selected gene expression data, gathered using standard methods of in situ hybridization and immunohistochemistry, are mapped to a representative 3D model for each chosen Carnegie stage. In these models, anatomical domains, defined on the basis of morphological landmarks and comparative knowledge of expression patterns in vertebrates, are linked to a developmental neuroanatomic ontology. Human gene expression patterns for genes with characteristic expression in different vertebrates (e.g. PAX6, GAD65 and OLIG2) are being used to confirm and/or refine the human anatomical domain boundaries. We have also developed interpolation software that digitally generates a full domain from partial data. Currently, the 3D models and a preliminary set of anatomical domains and ontology are available on the atlas pages along with gene expression data from approximately 100 genes in the HUDSEN Human Spatial Gene Expression Database (http://www.hudsen.org). The aim is that full 3D data will be generated from expression data used to define a more detailed set of anatomical domains linked to a more advanced anatomy ontology and all of these will be available online, contributing to the long-term goal of the atlas, which is to help maximize the effective use and dissemination of data wherever it is generated. [source]


MR-based visualization and quantification of three-dimensional flow characteristics in the portal venous system

JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2010
Zoran Stankovic MD
Abstract Purpose: To evaluate the feasibility of time-resolved flow-sensitive MRI for the three-dimensional (3D) visualization and quantification of normal and pathological portal venous (PV) hemodynamics. Materials and Methods: Portal venous hemodynamics were evaluated in 18 healthy volunteers and 5 patients with liver cirrhosis. ECG- and adaptive respiratory navigator gated flow-sensitive 4D MRI (time-resolved 3D MRI with three-directional velocity encoding) was performed on a 3 Tesla MR system (TRIO, Siemens, Germany). Qualitative flow analysis was achieved using 3D streamlines and time-resolved particle traces originating from seven emitter planes precisely placed at anatomical landmarks in the PV system. Quantitative analysis included retrospective extraction of regional peak and mean velocities and vessel area. Results were compared with standard 2D flow-sensitive MRI and to the reference standard Doppler ultrasound. Results: Qualitative flow analysis was successfully used in the entire PV system. Venous hemodynamics in all major branches in 17 of 18 volunteers and 3 of 5 patients were reliably depicted with good interobserver agreement (kappa = 0.62). Quantitative analysis revealed no significant differences and moderate agreement for peak velocities between 3D MR and 2D MRI (r = 0.46) and Doppler ultrasound (US) (r = 0.35) and for mean velocities between 3D and 2D MRI (r = 0.41). The PV area was significantly (P < 0.01) higher in 3D and 2D MRI compared with US. Conclusion: We successfully applied 3D MR velocity mapping in the PV system, providing a detailed qualitative and quantitative analysis of normal and pathological hemodynamics. J. Magn. Reson. Imaging 2010;32:466,475. © 2010 Wiley-Liss, Inc. [source]


Reality of the G-spot and its relation to female circumcision and vaginal surgery

JOURNAL OF OBSTETRICS AND GYNAECOLOGY RESEARCH (ELECTRONIC), Issue 5 2009
Saeed Mohamad Ahmad Thabet
Abstract Aim:, To clarify the reality of the G-spot anatomically, functionally and histologically, and to determine the possible effect of female circumcision and anterior vaginal wall surgery on the integrity and function of the G-spot. Methods:, A controlled descriptive and comparative cohort prospective study was conducted at Kasr El Aini School of Medicine, Cairo University, Cairo, Egypt, of 50 uncircumcised and 125 circumcised women with small to moderate anterior vaginal wall descent. Preoperative sexual examination was performed to map the site of the G-spot and other anatomical landmarks on the anterior vaginal wa11 and to verify the associated circumcision state. Pre- and postoperative sexual assessment and histological examination of different mapped sites in the anterior vagina were also conducted. Results:, Histological findings, results of the anatomical and sexual mapping of the anterior vaginal wall and sexual scores were recorded. The G-spot was proved functionally in 144 (82.3%) of women and anatomically in 95 (65.9%). The latter appeared as two small flaccid balloon-like masses on either side of the lower third of the urethra and were named ,the sexual bodies of the G-spot'. These bodies were significantly detected in all histo-positive cases in the circumcised women and in the uncircumcised women who had small or average clitorises. The G-spot was also proved histologically in 47.4% of all cases and was formed of epithelial, glandular and erectile tissue. Sex scores were significantly higher in the histo-positive cases with sexual bodies but significantly dropped after anterior vaginal wall surgery. In contrast, female circumcision rarely alters the scores. Conclusion:, The G-spot is functional reality in 82.3% of women, an anatomical reality in 54.3% and a histological reality in 47.4%. Anterior vaginal wall surgery usually affects the G-spot and female sexuality, but female circumcision rarely affects them. [source]


Precise landmarking in computer assisted total knee arthroplasty is critical to final alignment

JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 10 2010
Yaron S. Brin
Abstract Image-free computer navigation systems build a frame of reference of a patient's knee from anatomical landmarks entered by the surgeon during the initial stage of total knee arthroplasty. We performed tibial cuts on 70 sawbones using computer navigation. All landmarks were marked identically except for the tibial mechanical entry point, which was marked correctly in 10 bones and with offsets of 5, 10, and 15,mm medially and laterally in the others. The actual coronal angle of the tibial cuts was measured directly and compared to the final angle given by the navigation system. Significant deviations of the coronal angle were observed in the trial groups. Landmarking errors during navigated TKA can lead to inaccurate tibial bone cuts. This navigation system did not have an iterative software method to verify landmarking errors that can lead to inaccurate tibia bone cuts. Published by Wiley Periodicals, Inc. J Orthop Res 28:1355,1359, 2010 [source]


The Picture of the Linguistic Brain: How Sharp Can It Be?

LINGUISTICS & LANGUAGE COMPASS (ELECTRONIC), Issue 8 2010
Reply to Fedorenko & Kanwisher
What is the best way to learn how the brain analyzes linguistic input? Two popular methods have attempted to segregate and localize linguistic processes: analyses of language deficits subsequent to (mostly focal) brain disease and functional Magnetic Resonance Imaging (fMRI) in health. A recent Compass article by Fedorenko and Kanwisher (FK, 2009) observes that these methods group together data from many individuals through methods that rely on variable anatomical landmarks and that results in a murky picture of how language is represented in the brain. To get around the variability problem, FK propose to import into neurolinguistics a method that has been successfully used in vision research , one that locates functional Regions Of Interest (fROIs) in each individual brain. In this note, I propose an alternative perspective. I first take issue with FK's reading of the literature. I point out that, when the neurolinguistic landscape is examined with the right linguistic spectacles, the emerging picture , while intriguingly complex , is not murky, but rather, stable and clear, parsing the linguistic brain into functionally and anatomically coherent pieces. I then examine the potential value of the method that FK propose, in light of important micro-anatomical differences between language and high-level vision areas and conclude that as things stand the method they propose is not very likely to bear much fruit in neurolinguistic research. [source]


Anterior sciatic nerve block , new landmarks and clinical experience

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 4 2005
M. Wiegel
Background: Anterior sciatic nerve blocks can be complicated by several problems. Pain can be caused by bony contacts and, in obese patients, identification of the landmarks is frequently difficult. Methods: In a first step, 100 normal anterior-posterior pelvic X-rays were analyzed. The landmarks of the classical anterior approach were drawn on these X-rays and assessed for their sufficiency. Then, in a prospective case study, 200 consecutive patients undergoing total knee replacement were investigated. These patients received femoral and sciatic nerve catheters for postoperative pain management. Using modified anatomical landmarks, sciatic nerve catheters were inserted 5 cm distal from the insertion site of the femoral nerve block perpendicularly in the midline of the lower extremity. This midline connected the insertion site of the femoral nerve catheter to the midpoint between the medial and lateral epicondyle. Correct catheter positioning was verified by magnetic resonance imaging (MRI) in six patients. Results: Evaluation of pelvic X-rays showed that puncture following the classical landmarks pointed in 51% at the lesser trochanter, in 5% medial to the lesser trochanter and in 42% directly at the femur. In the latter patients, location of the sciatic nerve would have been difficult or even impossible. Using our modified anterior approach, the sciatic nerve could be blocked in 196 patients (98%). In nine patients (4.5%) blockade of the posterior femoral cutaneous nerve failed. Vascular puncture happened in 10 (5%) and bony contact in 35 patients (17.5%). Median puncturing depth was 9.5 (7.5,14) cm. Correct sciatic nerve catheter positioning was verified in all patients who underwent MRI. Conclusion: Our landmarks for locating the sciatic nerve help to avoid bony contacts and thereby reduce pain during puncture. Our method reliably enabled catheter placement. [source]


Advances in insectivore and rodent systematics due to geometric morphometrics

MAMMAL REVIEW, Issue 2 2009
LENKA BAR
ABSTRACT 1Morphometrics, the study of the variation and change in form amongst organisms, serves as a basic methodological tool in various fields of biological research, including systematics. Because it includes information about spatial relationships amongst anatomical landmarks, geometric morphometrics is more suitable for analyzing morphometric variation than methods based on distance measurements. 2Geometric morphometrics allows us to answer general ecological and evolutionary questions about shape. 3In this paper, landmark-based methods are described and illustrated, based on a dataset of measurements from 295 Apodemus mandibles, and the applications of such methods in the systematics of insectivores (Eulipotyphla) and rodents (Rodentia) are summarized. [source]


Technical note: Virtual reconstruction of a fragmentary clavicle

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2009
Stefano Benazzi
Abstract We report a procedure for the virtual reconstruction of incomplete human bones applicable to skeletal remains from archaeological excavations or to reconstructive and prosthetic surgery. To test the procedure, we reconstructed a fragmented left clavicle on the basis of the contralateral clavicle. The procedure involved 3-D laser scanner acquisition of the left clavicle (complete but broken into two parts), the same manually reconstructed bone, and the intact right clavicle, which was mirror-imaged and used as a reference for the reconstruction of the whole left clavicle. Because it was not possible to recognize homologous anatomical landmarks, on the two reference models (a mirror-image copy of the right clavicle and the main fragment of the left), we identified three grids with an increasing number of corresponding landmarks, which constituted the framework of the deformation process. The three reconstructed digital models of the clavicle closely approximated the model of the original clavicle. They also showed that an increasing number of landmarks did not significantly improve the reconstructed model. Am J Phys Anthropol 2009. © 2009 Wiley-Liss, Inc. [source]


ORIGINAL ARTICLE: The ability of anaesthetists to identify the position of the right internal jugular vein correctly using anatomical landmarks

ANAESTHESIA, Issue 9 2010
C. R. Harber
Summary We performed a study of 85 consenting anaesthetists to assess their ability to locate the right internal jugular vein using a landmark technique. Initially, a questionnaire was completed ascertaining previous user experience. An ultrasound probe, using the midpoint as an ,imaginary needle', was placed on the neck of a healthy volunteer (with previously confirmed normal anatomy) and the image recorded. Both anaesthetist and volunteer were blinded to the screen until the image was stored. Anaesthetists were grouped into those in training before 2002 (Pre-2002, n = 58), when National Institute for Health and Clinical Excellence guidelines recommending ultrasound guidance were published, and those training after this time point (Post-2002, n = 27). The success rate for identifying the internal jugular vein using the landmark technique was 36/58 (62%) in the Pre-2002 group and 6/27 (22%) in the Post-2002 group (p < 0.001). Three participants in each group would have hit the carotid artery (5% Pre-2002 and 11% Post-2002 respectively; p = 0.2). The advent of routine use of ultrasound has resulted in a cohort of anaesthetists who are unable to use a landmark technique effectively or safely. This has significant training implications. [source]


ORIGINAL ARTICLE: Accuracy of surface landmark identification for cannula cricothyroidotomy

ANAESTHESIA, Issue 9 2010
D. S. J. Elliott
Summary Cannula cricothyroidotomy is recommended for emergency transtracheal ventilation by all current airway guidelines. Success with this technique depends on the accurate and rapid identification of percutaneous anatomical landmarks. Six healthy subjects underwent neck ultrasound to delineate the borders of the cricothyroid membrane. The midline and bisecting transverse planes through the membrane were marked with an invisible ink pen which could be revealed with an ultraviolet light. Eighteen anaesthetists were then invited to mark an entry point for cricothyroid membrane puncture. Only 32 (30%) attempts by anaesthetists accurately marked the skin area over the cricothyroid membrane. Of these only 11 (10%) marked over the centre point of the membrane. Entry point accuracy was not significantly affected by subjects' weight, height, body mass index, neck circumference or cricothyroid dimensions. Consultant and registrar anaesthetists were significantly more accurate than senior house officers at correctly identifying the cricothyroid membrane. Accuracy of percutaneously identifying the cricothyroid membrane was poor. Ultrasound may assist in identifying anatomical landmarks for cricothyroidotomy. [source]


Evaluation of the novel, single-use, flexible aScope® for tracheal intubation in the simulated difficult airway and first clinical experiences

ANAESTHESIA, Issue 8 2010
T. Piepho
Summary Flexible fibreoptic intubation is widely accepted as an important modality for the management of patients with difficult airways. We compared the aScope®, a novel, single-use, flexible video-endoscope designed to aid tracheal intubation, with a standard flexible intubating fibrescope, by examining the performance of 21 anaesthetists during an easy and difficult intubation simulation in a manikin. Intubation success, time for intubation, and rating of the devices (using a scale from 1, excellent to 6, fail) were documented. Intubation times were similar for both flexible 'scopes in the scenarios (p = 0.59). Successful intubation rates were higher for the standard intubating fibrescope (17/21, 81%) than the aScope (14/21, 67%; p = 0.02) in the difficult intubation scenario. The median (IQR[range]) ratings for the standard fibrescope vs the aScope were respectively: overall, 2 (1.75,2 [1,2.5]) vs 3 (2,3.25 [1,5]) (p < 0.0001); picture quality 2 (1.5,2 [1,3]) vs 3 (2,4 [1,5]) (p < 0.0001). The aScope was also successfully used to facilitate tracheal intubation in five patients with anticipated or unanticipated difficult airways. Picture quality was sufficient to identify the anatomical landmarks. Although the performance of the aScope is acceptable, it does not meet the current quality of standard flexible intubation fibrescopes. [source]


Locating the arcuate line of Douglas: Is it of surgical relevance?

CLINICAL ANATOMY, Issue 1 2010
P.M. Mwachaka
Abstract Ventral hernia formation is a common complication of rectus abdominis musculocutaneous flap harvest. The site and extent of harvest of the flap are known contributing factors. Therefore, an accurate location of the arcuate line of Douglas, which marks the lower extent of the posterior wall of the rectus sheath, may be relevant before harvesting the flap. This study is aimed at determining the position of the arcuate line in relation to anatomical landmarks of the anterior abdominal wall. Arcuate lines were examined in 80 (44 male, 36 female) subjects, aged between 18 and 70 years, during autopsies and dissection. The position of the arcuate line was determined in relation to the umbilicus, pubic symphysis, and intersections of rectus abdominis muscle. Sixty four (80.4%) cases had the arcuate line. In most cases (52), this line was located in the upper half of a line between the umbilicus and the pubic symphysis. Most males (93%) had the arcuate line, while more than a third of females did not have it. In all these cases, the line occurred bilaterally as a single arcade, constantly at the most distal intersection of the rectus abdominis muscle. Consequently, the arcuate line is most reliably marked superficially by the distal tendinous intersection of the rectus abdominis muscle. Harvesting of the muscle cranial to this point will minimize defects in the anterior abdominal wall that may lead to hernia formation. Clin. Anat. 23:84,86, 2010. © 2009 Wiley-Liss, Inc. [source]


A morphometric study of the inferior orbital fissure using three-dimensional anatomical landmarks: Application to orbital surgery

CLINICAL ANATOMY, Issue 6 2009
Mehmet Asim Ozer
Abstract The inferior orbital fissure (IOF) is an important structure during orbital surgery, however, neither its anatomical features nor the procedures necessary to expose the IOF have been examined in detail. A morphometric analysis of the IOF was performed on 232 orbits using computer software. The longest and shortest borders of the IOF were 18.2 ± 4.9 and 1.9 ± 1.3 mm, respectively. The outer and the inner angles were 138.9 ± 32.7° and 38.4 ± 24.7°, respectively. The perimeter of the IOF was 50.6 ± 13.5 mm and its area was 61.3 ± 39.1 mm2. Eight types of IOF were observed. Type 1 IOF was observed in 42.2% and the Type 2 IOF was identified in 15.9%. A statistically significant relation was found between the longest edge and area and the widest edge and area of the IOF. The findings of our study suggest that the removal of the lateral wall should begin inferiorly, just lateral to the IOF and extended superolaterally. These data may be useful during surgical approaches to the orbit. Clin. Anat. 22:649,654, 2009. © 2009 Wiley-Liss, Inc. [source]


The "safe zone" in medial percutaneous calcaneal pin placement

CLINICAL ANATOMY, Issue 4 2009
Zakareya Gamie
Abstract Percutaneous pin insertion into the medial calcaneus places a number of structures at risk. Evidence suggests that the greatest risk is to the medial calcaneal nerve (MCN). The medial calcaneal region of 24 cadavers was dissected to determine the major structures at risk. By using four palpable anatomical landmarks, the inferior tip of the medial malleolus (point A), the posterior superior portion of the calcaneal tuberosity (point B), the navicular tuberosity (point C), and the medial process of the calcaneal tuberosity (point D), we attempted to define the safe zone taking into account all possible variables in our dissections including ankle position, side, gender, and possible anatomical variations of the MCN. The commonest arrangement of the MCN was two MCNs that arose independently, one arising before the bifurcation of the tibial nerve and the other arising from the medial plantar nerve. A zone could be defined posterior to 75% of the distance along the lines AB, CD, AD, and CB which would avoid most structures. The posterior branches of the MCN, however, would still be at risk and placing the pin too far posteriorly risks an avulsion fracture. This is the first study to employ four palpable anatomical landmarks to identify a zone to minimize damage to neurovascular structures. It may not be possible, however, to avoid injury of the MCN and consequent sensory loss to the sole of the foot. foot. Clin. Anat. 22:523,529, 2009. © 2009 Wiley-Liss, Inc. [source]