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Results for “Anatomic Landmarks”

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At least 19 recordsLinked to original sources

PubMedDate not supplied

Relationship of the inguinal ligament to pelvic radiographic landmarks: anatomic correlation and its role in femoral arteriography.

PURPOSE: Because of the known risks of suprainguinal catheterization, an anatomic study of the inguinal ligament was performed in 10 cadavers. MATERIALS AND METHODS: The position of the inguinal ligament as estimated by means of palpation and use of anatomic landmarks was compared with the actual ligament position as determined by means of groin dissection. Infrainguinal contrast material injections were also performed to assess competence of the inguinal ligament against spread of hematomas. RESULTS: The radiographically determined position was an average of 15.2 mm superior to the actual ligament position (range, 3 mm below to 24 mm above). The palpated position of the ligament was an average of 7.8 mm superior to its actual position (range, 7 mm below to 23 mm above). Contrast material injections demonstrated the inability of the inguinal ligament to contain blood or fluid, with formation of retroperitoneal hematomas. CONCLUSION: Puncture of the femoral vessels should be positioned in the midportion of the femoral head, as determined with fluoroscopy for maximum safety during catheterizations.

Angiography↗

PubMed1999

Are anatomic landmarks reliable in determination of fusion level in posterolateral lumbar fusion?

STUDY DESIGN: Determination of the fusion level by direct observation and palpation of anatomic landmarks is compared with the finding obtained from a lateral intraoperative radiograph. OBJECTIVES: To assess the reliability of the use of intraoperative anatomic landmarks in determination of the fusion level. SUMMARY OF BACKGROUND DATA: Accurate determination of the level to be fused in noninstrumented posterolateral fusion is crucial. No studies are available in which the value of direct observation and palpation of the anatomic landmarks in determination of the fusion level has been assessed. METHODS: Eighty patients who underwent posterolateral fusion without instrumentation in the lumbosacral spine were included in this study. During surgery, first, the cephalad transverse process at the desired level to be fused was determined by direct observation and palpation of the anatomic landmarks; second, a metal mark was placed beneath the cephalad transverse process at the level determined by anatomic landmarks. This was followed by a lateral radiograph. The consistency and discrepancy between the use of the anatomic landmarks and lateral radiography in determining the desired fusion level were recorded. RESULTS: The fusion level determined by direct observation and palpation of the anatomic landmarks was accurate in 76 (95%) cases. In the remaining four cases, intraoperative x-rays determined that the selection of the cephalad transverse process for fusion was one level too high in three cases and one level too low in the other case. All errors in determination of the level to be fused occurred in patients who had extensive laminectomy at L4-S1. CONCLUSIONS: Determination of fusion level by direct observation and palpation of the anatomic landmarks is not reliable in patients who have had or require decompressive procedures. A lateral radiograph should be routinely obtained for accurate identification of the level to be fused.

Adult↗

PubMed2001

Anatomic landmarks to estimate the length of the diaphragm from chest radiographs: effects of emphysema and lung volume reduction surgery.

STUDY OBJECTIVES: To define anatomic landmarks that can be used to predict insertions of the diaphragm on chest radiographs and to estimate diaphragm length. DESIGN: Prospective clinical trial with a parallel group design. SETTING: Laboratory investigations in normal volunteers recruited by advertisement and in emphysema outpatients being evaluated for elective bilateral lung volume reduction surgery (LVRS). PATIENTS: Twenty-six normal subjects classified into young and older age groups, with a third group of 13 emphysema patients matched for age and sex with the older group. MEASUREMENTS: Identification and between-group comparisons were made of anatomic landmarks on anteroposterior and lateral chest radiographs obtained at total lung capacity. Predicted landmarks were generated from normal subjects. Within-subject and between-group comparisons were made of diaphragm length index (DLI) based on observed anatomic landmarks (DLIobs) and diaphragm length index based on predicted anatomic landmarks (DLIpred) at functional residual capacity. RESULTS: Anatomic landmarks were not different between the three groups or between male and female subjects, and were not different before and after LVRS in emphysema patients. No difference was found between DLIobs and DLIpred in normal subjects and emphysema patients, but both were smaller in emphysema patients than in normal subjects and increased after LVRS in emphysema patients. CONCLUSION: This study validates the use of anatomic landmarks to estimate DLI. Using these landmarks simplifies the determination of diaphragmatic lengths and could be a useful tool for the evaluation of the functional capacity of the diaphragm, and possibly as a prognostic indicator of patients who are candidates for LVRS.

Adult↗

PubMed2003

The superior petrosal triangle as a constant anatomical landmark for subtemporal middle fossa orientation.

UNLABELLED: 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.

Cranial Fossa, Middle↗

PubMed2005

Human movement analysis using stereophotogrammetry. Part 4: assessment of anatomical landmark misplacement and its effects on joint kinematics.

Estimating the effects of different sources of error on joint kinematics is crucial for assessing the reliability of human movement analysis. The goal of the present paper is to review the different approaches dealing with joint kinematics sensitivity to rotation axes and the precision of anatomical landmark determination. Consistent with the previous papers in this series, the review is limited to studies performed with video-based stereophotogrammetric systems. Initially, studies dealing with estimates of precision in determining the location of both palpable and internal anatomical landmarks are reviewed. Next, the effects of anatomical landmark position uncertainty on anatomical frames are shown. Then, methods reported in the literature for estimating error propagation from anatomical axes location to joint kinematics are described. Interestingly, studies carried out using different approaches reported a common conclusion: when joint rotations occur mainly in a single plane, minor rotations out of this plane are strongly affected by errors introduced at the anatomical landmark identification level and are prone to misinterpretation. Finally, attempts at reducing joint kinematics errors due to anatomical landmark position uncertainty are reported. Given the relevance of this source of errors in the determination of joint kinematics, it is the authors' opinion that further efforts should be made in improving the reliability of the joint axes determination.

Biomechanical Phenomena↗

PubMed2004

[Anatomical landmarks of skull base and safety of the skull base surgery].

OBJECTIVE: In order to improve the safety of skull base surgery and to completely resect the skull base tumors, the anatomical landmarks of skull base were studied. METHODS: 29 cases of skull base surgery were performed between 1992 and 2002, and their clinical data were retrospectively analysed. The anatomical landmarks of cranial base, such as comb, pterygoid process, spine of temporal bone, styloid process, and internal caroid artery, were analysed in preoperative diagnosis and operative treatment of various kinds of skull base tumors. RESULTS: In the early stages, because of lacking the knowledge of anatomical landmarks of the skull base, the surgery lasted longer, part of skull base tumors remained and operative blood lose was much more than that in later stage. In the later stage, no operative death and severe complications were found in 26 cases which underwent various kinds of skull base surgery. The survival rates at 3 and 5 years were 72.2% and 35.7% respectively for malignant tumors. CONCLUSIONS: Comb, pterygoid process, spine of temporal bone, styloid process, internal caroid artery and their adjacent structures were important anatomical landmarks for operative treatment of anterior, middle and lateral cranial base tumors. It was important to know the anatomical landmarks to ensure the safety of the skull base surgery.

Adolescent↗

PubMed2002

Anatomic landmarks and time management during retroperitoneoscopic radical nephrectomy.

BACKGROUND AND PURPOSE: Retroperitoneoscopy has not been widely considered the preferred approach to laparoscopic radical nephrectomy for cancer, in part because the retroperitoneal anatomic landmarks have not been well defined. The aim of this study is to provide prospective, objective data on retroperitoneoscopic radical nephrectomy with regard to anatomic landmarks and time management of the sequential operative steps. MATERIALS AND METHODS: A uniform database was devised to record predetermined intraoperative parameters prospectively in 18 consecutive retroperitoneoscopic radical nephrectomies. RESULTS: A three- or four-port technique was employed to perform 10 left and 8 right retroperitoneoscopic radical nephrectomies. Initial balloon dilation was routinely performed outside of and posterior to Gerota's fascia. The anatomic landmarks visible immediately on initial insertion of the laparoscope were: psoas muscle in 18 cases (100%), Gerota's fascia in 18 (100%), peritoneal reflection in 15 (83%), ureter and/or gonadal vein in 11 (61%), and renal artery pulsations in 10 (56%). Aortic pulsations were seen in 9 of 10 left (90%) and the inferior vena cava in 2 of 8 right (25%) radical nephrectomies. The mean surgical time was 203 +/- 52.9 minutes (range 105-290 minutes). The sequential operative steps and their individual time breakdowns were: port placement 12 +/- 3.9 minutes, hilar dissection 63 +/- 29.1 minutes, adrenal mobilization 49 +/- 12.1 minutes, specimen mobilization 19 +/- 20.8 minutes, and specimen entrapment and exit 23 +/- 18.2 minutes. When the initial balloon dilation resulted in visibility of four or more anatomic landmarks, the hilar dissection time was significantly shorter (P < 0.001). CONCLUSIONS: Proper development of the retroperitoneal space and identification of adequate anatomic landmarks is important during retroperitoneoscopy. This timed analysis of the sequential operative steps of retroperitoneoscopic radical nephrectomy has served as an important self-assessment tool for us in improving our surgical technique. As a result, our surgical time for retroperitoneoscopic radical nephrectomy has decreased from the earlier 4- to 5-hour range to the current 2- to 3-hour range.

Aged↗

PubMed1987

Movement of the human pelvis and displacement of related anatomical landmarks on the body surface.

Anatomical landmarks on the body surface can be measured with high accuracy by using rasterstereography and surface curvature analysis. The present study shows that the lumbar dimples can be localized with a statistical error of about 1 mm. It is generally assumed that the dimples are in close relation to the pelvis (in particular to the PSISs) and may thus be taken as indicators for pelvis movements. By introducing an artificial pelvis tilt of up to +/- 10 degrees this relation was examined. In fact, a nearly perfect correlation (r approximately equal to 0.99) between landmark and pelvis movements was observed. Asymmetries of pelvis motion due to scoliotic deformity were not observed. There was, however, a systematic lag of the dimple movements, resulting in a displacement of the dimples of up to +/- 1.5 mm relative to the pelvis (for +/- 10 degrees pelvis tilt). Either a soft tissue effect or a torsion of the pelvis may be responsible for this behaviour. The theory of pelvis torsion is confirmed by the fact that the orientation of the back surface at the locus of the dimples reveals a corresponding torsion of similar magnitude and sign. A torsion angle of about +/- 1.5 degrees in either sacro-iliac joint is sufficient to explain the observed dimple lag and the surface torsion. An independent measurement (e.g. using roentgenphotogrammetry) would be desirable to further validate this theory. According to our measurements the dimples of the PSISs cannot be taken as exact indicators for orientation and movement of the pelvis.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗

PubMed2006

Propagation of anatomical landmark misplacement to knee kinematics: performance of single and double calibration.

Soft tissue artefact and anatomical landmark misplacement have been recognized as the most critical sources of error in gait analysis. The double calibration method was recently proposed to compensate for soft tissue artefact in knee kinematics. This compensation method resulted very effective in the absence of anatomical landmark misplacement. The purpose of the present work was to assess the effectiveness of double calibration in reducing the effects of skin motion artefact on knee rotations and translations when anatomical landmark misplacement is present on the thigh and shank. The double calibration method was used to calculate knee kinematics of two subjects while they performed several motor tasks. The results were compared with those from conventional single calibration. The soft tissue artefact propagated to knee kinematics was quantified by simulating different misplacement errors using both single and double calibration. The double calibration method performed much better than the single calibration one in quantifying knee rotations and particularly translations, with misplacement error up to 15mm superimposed on the anatomical coordinates of the epicondyles. If misplacement errors were limited to just 5mm, the double calibration would be effective in providing kinematics accurate enough for orthopaedic biomechanic applications.

Adult↗

PubMed1977

Radiographic anatomical landmarks of the metacarpo-phalangeal joints.

The location of cortical bone changes in the metacarpo-phalangeal joints has been variously described as periarticular, juxta-articular, articular, or subarticular. Suitable radiographic landmarks on anatomical specimens were sought to assess the cartilage-covered articular surfaces of these joints. Precise landmarks for the limits of the joint space are not available, but unequivocal intra-articular regions were identified.

Finger Joint↗

PubMed2005

A three-dimensional active shape model for the detection of anatomical landmarks on the back surface.

In this study relations between anatomical landmarks on the dorsal surface of the human torso corresponding to underlying skeletal structures are established. By examining the statistics of the positions of the landmarks in a training set of subjects a point distribution model is derived. Rotations of the pelvis are simulated in order to show that the main mode shapes of variation are consistent with rotations of the pelvis relative to the trunk. The parameters of these mode shapes can therefore be used as independent measures of clinical parameters such as pelvic inclination, pelvic tilt, etc. The point distribution model is further applied to improve reliability and robustness for an automatic and objective detection of the anatomical landmarks on the back surface (active shape model). The results show that it is possible to replace radiographs by surface measurements in order to measure position and orientation of the pelvis, which is particularly valuable in the case of functional examinations that normally involve a large number of radiographs (e.g. to measure the position of the pelvis in a scoliosis).

Adolescent↗

PubMed2005

Anatomic landmarks for nerves of the neck: a vade mecum for neurosurgeons.

Anatomic landmarks are often quite useful in localizing structures within the human body, especially in the surgical realm. We have reviewed the medical literature and multiple texts of surgery and anatomy and culled together many anatomic landmarks regarding important nerves of the neck. This region is complicated by formidable anatomy, and a single collection of the relationships of the nerves in this region is lacking in the literature. It is our hope that this collection will serve to assist the surgeon who operates in this region of the body.

Humans↗

PubMed2006

Reliability of anatomical landmarks for skin perforators of the thoracodorsal artery perforator flap.

BACKGROUND: The thoracodorsal artery perforator flap was first introduced in 1995. Many authors focused on using anatomical landmarks to identify skin perforators and on thinning procedures for a skin paddle. In this study, we used the superthin free thoracodorsal artery perforator flap for resurfacing shallow defects of the extremities in 10 patients. METHODS: Two anatomical landmarks previously presented by other authors were used for the guidance of flap elevation. The first landmark represented the site of the proximal skin perforator originating from the descending branch of the thoracodorsal artery, and the second landmark marked the site of the thoracodorsal neurovascular hilum. Ten flaps were performed, and all skin perforators originated from the descending branch of the thoracodorsal artery. The skin paddle carried only skin and the superficial adipose layer, and the largest skin paddle was 23 x 9 cm. RESULTS: All defects were resurfaced with smooth contour, except for one flap in which the authors encountered flap tip superficial necrosis. The operative findings did not coincide with the first anatomical landmark in five patients. Likewise, these findings were not consistent with the second landmark in eight patients. In four patients, the thoracodorsal neurovascular hilum was located at the same level of the scapular tip or even above it. These unwanted anatomical variations increased the difficulty of exploration for skin perforators. CONCLUSIONS: The thoracodorsal artery perforator flap is a feasible choice for shallow defects in superthin form. Using a color Doppler device to identify the skin perforators preoperatively is highly suggested to prevent unexpected anatomical variations.

Adult↗

PubMed2004

MR-guided stereotactic neurosurgery--comparison of fiducial-based and anatomical landmark transformation approaches.

For application in magnetic resonance (MR) guided stereotactic neurosurgery, two methods for transformation of MR-image coordinates in stereotactic, frame-based coordinates exist: the direct stereotactic fiducial-based transformation method and the indirect anatomical landmark method. In contrast to direct stereotactic MR transformation, indirect transformation is based on anatomical landmark coregistration of stereotactic computerized tomography and non-stereotactic MR images. In a patient study, both transformation methods have been investigated with visual inspection and mutual information analysis. Comparison was done for our standard imaging protocol, including t2-weighted spin-echo as well as contrast enhanced t1-weighted gradient-echo imaging. For t2-weighted spin-echo imaging, both methods showed almost similar and satisfying performance with a small, but significant advantage for fiducial-based transformation. In contrast, for t1-weighted gradient-echo imaging with more geometric distortions due to field inhomogenities and gradient nonlinearity than t2-weighted spin-echo imaging, mainly caused by a reduced bandwidth per pixel, anatomical landmark transformation delivered markedly better results. Here, fiducial-based transformation yielded results which are intolerable for stereotactic neurosurgery. Mean Euclidian distances between both transformation methods were 0.96 mm for t2-weighted spin-echo and 1.67 mm for t1-weighted gradient-echo imaging. Maximum deviations were 1.72 mm and 3.06 mm, respectively.

Algorithms↗

PubMed2003

Asynchronous confirmation of anatomical landmarks by optical capture in open surgery.

HYPOTHESIS: Asynchronous remote telementoring and teleproctoring with anatomical subject matter relevant to surgical procedures is an effective instructional tool for surgical trainees. DESIGN: A validation model was established to assess the capabilities of current technologies to conduct effective instruction of surgical procedures in a remote location relative to the actual surgical procedure. A total of 23 unilateral thyroid dissections in 13 patients using a laparoscope affixed to a stationary robotic arm were videotaped. Anatomical confirmation was sought for the superior flap, middle thyroid vein, carotid sheath, 2 parathyroids, inferior thyroidal artery, recurrent laryngeal nerve, and superior thyroid pole. MAIN OUTCOME MEASURES: Ten surgical trainees reviewed video segments of these 8 anatomical landmarks at a later time after surgery. During observation of the video segments, these physicians were asked to validate the anatomical landmarks on a survey by choosing concur, do not concur, or uncertain. The review panel was also asked to score the images for quality of light, focus (clarity), field range, and contrast. CONCLUSION: This study validates the use of asynchronous education with high-quality optical capture for distance education and collaboration in open surgery.

Education, Distance↗

PubMed2001

Safety and efficacy of intraarticular hip injection using anatomic landmarks.

This study tests the hypotheses that the hip can be injected safely and reliably, using anatomic landmarks, without fluoroscopic guidance. Fifteen human cadavers (30 hips) were injected, each receiving one anterior hip injection and one lateral hip injection with methylene blue dye. Anatomic dissections were done on all 30 specimens to determine the rate of success and the proximity of the needle to the neurovascular structures about the hip with each approach. Neither the anterior nor the lateral injection approach, using published techniques based on anatomic landmarks, was sufficiently reliable to recommend for clinical use without radiographic guidance; the anterior approach was successful in only 60% of injections, and the lateral technique was successful in 80% of injections. In addition, the anterior approach, which is recommended in more reference works than any other approach, resulted in significantly more risk to the femoral nerve than did the lateral approach. The needle pierced or contacted the femoral nerve in 27% of anterior injections and was within 5 mm of the femoral nerve in 60% of anterior attempts. The anterior injection approach also resulted in needle placements significantly closer to the femoral artery and the lateral femoral cutaneous nerve than did the lateral approach. Using the lateral approach, the needle was never within 25 mm of any neurovascular structure in any injection. Some form of radiographic or sonographic guidance is recommended for needle placement during hip injections and aspirations; the lateral approach for needle placement seems safer than the anterior approach, with respect to the possibility of neurovascular injury.

Adult↗

PubMedDate not supplied

Ultrasonography of the normal feline pancreas and associated anatomic landmarks: a prospective study of 20 cats.

The sonographic appearance of the feline pancreas and associated anatomic landmarks including the pancreatic duct, duodenum, duodenal papilla, portal vein, and gastric lymph node were evaluated in 20 healthy, awake cats. The pancreas appeared nearly isoechoic to surrounding mesenteric tissues, isoechoic to slightly hyperechoic to adjacent liver lobes, and hypoechoic to the spleen. The mean thickness measurements for the right pancreatic lobe, body, and left pancreatic lobe were 4.5 mm (range 2.8-5.9), 6.6 mm (range 4.7-9.5), and 5.4 mm (range 3.4-9.0), respectively. The pancreatic duct was consistently visualized in the left pancreatic lobe and had a mean thickness of 0.8 mm (range 0.5-1.3). It could be differentiated from the pancreatic vessel, by its central location, and the duct's lack of Doppler flow signal. The duodenum was used as a landmark to identify the right lobe of the pancreas. The mean duodenal wall thickness measurement was 2.8 mm (range 2.1-3.8) in sagittal section, and 3.0 mm (range 2.2-4.4) in transverse section. The duodenal papilla was identified in 4 of 20 cats. It ranged in size from 2.9 to 5.5 mm in width, and had a maximum height of 4.0 mm in transverse section. The portal vein was used as a consistent anatomic landmark for identification of the left lobe and body of the pancreas. The mean diameter of the portal vein at the level where the pancreatic body joins the left pancreatic lobe was 4.3 mm (range 2.7-5.9) when viewed in sagittal section, and 4.5 mm (range 3.6-6.1) in transverse section. The gastric lymph node was identified cranial and ventromedial to the pyloroduodenal angle in 6 of 20 cats. It had an asymmetrical shape with a larger caudal pole in five of the six cats. The largest dimensions of the gastric lymph node were 10 mm in length, and 6 mm in width for the larger caudal pole, and 5.1 mm in width for the smaller cranial pole.

Animals↗

PubMed2002

An interactive, web-based tool for learning anatomic landmarks.

PURPOSE: To evaluate the effectiveness of a Web-based interactive teaching tool that uses self-assessment exercises with real-time feedback to aid students' learning in a gross anatomy class. METHOD: A total of 107 of 124 first-year medical students at one school were enrolled in the study. Students were divided into three groups: Group 1 (n = 63) received introductory material and activated their Web-based accounts; Group 2 (n = 44) received introductory material but did not activate their Web-based accounts; and Group 3 (n = 17) were not enrolled in the study and received no introductory material. Students in Group 1 had access to a graphic showing the locations of anatomic landmarks, a drill exercise, and a self-evaluation exercise. Students' ability to identify the anatomic landmarks on a 30-question midterm and a 30-question final exam were compared among the groups. RESULTS: The mean scores of students in Group 1 (midterm = 28.5, final = 28.1) were significantly higher than were the mean scores of students in Group 2 (midterm = 26.8, p <.001; final = 26.9, p <.017) and Group 3 (midterm = 24.8, p <.001; final = 26.4, p <.007). CONCLUSIONS: The Web-based tool was effective in improving students' scores on anatomic landmark exams. Future studies will determine whether the tool aids students in identifying structures located in three-dimensional space within regions such as the cranium and the abdominal cavity.

Adult↗