Landmark Measurements Research Articles

Accuracy of pelvic bone segmentation for 3d printing: a study of segmentation accuracy based on anatomic landmarks to evaluate the influence of the observer.

3D printing has a wide range of applications and has brought significant change to many medical fields. However, ensuring quality assurance (QA) is essential for patient safety and requires a QA program that encompasses the entire production process. This process begins with imaging and continues on with segmentation, which is the conversion of Digital Imaging and Communications in Medicine (DICOM) data into virtual 3D-models. Since segmentation is highly influenced by manual intervention the influence of the users background on segmentation accuracy should be thoroughly investigated. Seventeen computed tomography (CT) scans of the pelvis with physiological bony structures were identified, anonymized, exported as DICOM data sets, and pelvic bones were segmented by four observers with different backgrounds. Landmarks were measured on DICOM images and in the segmentations. Intraclass correlation coefficients (ICCs) were calculated to assess inter-observer agreement, and the trueness of the segmentation results was analyzed by comparing the DICOM landmark measurements with the measurements of the segmentation results. The correlation between segmentation trueness and segmentation time was analyzed. The lower limits of the 95% confidence intervals of the ICCs for the seven landmarks analyzed ranged from 0.511 to 0.986. The distance between the iliac crests showed the highest agreement between observers, while the distance between the ischial tuberosities showed the lowest. The distance between the upper edge of the symphysis and the promontory showed the lowest deviation between DICOM measurements and segmentation measurements (mean deviations < 1mm), while the intertuberous distance showed the highest deviation (mean deviations 14.5-18.2mm). Investigators with diverse backgrounds in segmentation and varying experience with slice images achieved pelvic bone segmentations with landmark measurements of mostly high agreement in a setup with high realism. In contrast, high variability was observed in the segmentation of the coccyx. In general, interobserver agreement was high, but due to measurement inaccuracies, landmark-based approaches cannot conclusively show that segmentation accuracy is within a clinically tolerable range of 2mm for the pelvis. If the segmentation is performed by a very inexperienced user, the result should be reviewed critically by the clinician in charge.

Retrospective analysis of the upper airway anatomy and Sella turcica morphology across different skeletal malocclusions: a computerized technique

ObjectiveThis study aimed to investigate the normal volumetric space and variations in the measurements of different landmarks in adults with different skeletal relations of the maxilla and the mandible based on CBCT data. The study also analyses these landmarks to locate any correlations.BackgroundNumerous studies in orthodontics have found a relationship between orthodontic treatment and changes in the anatomy and function of the airway. Severe changes in airway morphology can cause breathing difficulties, lower quality of life, and even result in life-threatening conditions such as obstructive sleep apnoea. Consequently, orthodontic diagnosis and treatment planning require a thorough understanding of the airway space and its function.MethodsThe present retrospective study was conducted using CBCT records of 120 adult patients, containing 40 samples of each skeletal class (20 males and 20 females). The boundaries were defined for the 3 major regions: the nasopharynx, the oropharynx, and the hypopharynx. Various measurements were recorded across these regions, as well as selective cephalometric landmarks. The obtained data was used to calculate average and standard deviation, while regression analysis was used to evaluate correlations and t-test was used to test statistical significance of gender differences.ResultsThe results demonstrate that skeletal Class III individuals exhibit a reduced airway volume in the nasopharynx compared to other groups, whereas skeletal Class II individuals displayed a diminished airway volume in the hypopharynx. A strong correlation was observed for Sella turcica parameters. There were no significant differences in skeletal parameters across genders. Nasopharynx cavity volume demonstrated significant differences between skeletal Class I–Class III as well as between skeletal Class II–Class III. Hypopharynx cavity volume also demonstrated significant differences between skeletal Class I–Class II and between skeletal Class II–Class III.ConclusionThe major findings are the presence of a reduced nasopharyngeal volume in skeletal Class III malocclusions while skeletal Class II individuals displayed a diminished hypopharyngeal volume, making these critical areas to consider during the diagnostic and orthodontic treatment planning stages. This study also revealed a consistent correlation between Sella turcica parameters across various facial skeletal profiles, with skeletal Class II patients exhibiting a distinct pattern and skeletal Class I and Class III demonstrating an average relationship.

Development and validation of predictive models for skeletal malocclusion classification using airway and cephalometric landmarks

ObjectiveThis study aimed to develop a deep learning model to predict skeletal malocclusions with an acceptable level of accuracy using airway and cephalometric landmark values obtained from analyzing different CBCT images.BackgroundIn orthodontics, multitudinous studies have reported the correlation between orthodontic treatment and changes in the anatomy as well as the functioning of the airway. Typically, the values obtained from various measurements of cephalometric landmarks are used to determine skeletal class based on the interpretation an orthodontist experiences, which sometimes may not be accurate.MethodsSamples of skeletal anatomical data were retrospectively obtained and recorded in Digital Imaging and Communications in Medicine (DICOM) file format. The DICOM files were used to reconstruct 3D models using 3DSlicer (slicer.org) by thresholding airway regions to build up 3D polygon models of airway regions for each sample. The 3D models were measured for different landmarks that included measurements across the nasopharynx, the oropharynx, and the hypopharynx. Male and female subjects were combined as one data set to develop supervised learning models. These measurements were utilized to build 7 artificial intelligence-based supervised learning models.ResultsThe supervised learning model with the best accuracy was Random Forest, with a value of 0.74. All the other models were lower in terms of their accuracy. The recall scores for Class I, II, and III malocclusions were 0.71, 0.69, and 0.77, respectively, which represented the total number of actual positive cases predicted correctly, making the sensitivity of the model high.ConclusionIn this study, it is observed that the Random Forest model was the most accurate model for predicting the skeletal malocclusion based on various airway and cephalometric landmarks.

A Novel Surgical Landmark to Identify the Recurrent Laryngeal Nerve

Although several surgical landmarks have been proposed to localize the recurrent laryngeal nerve (RLN), there is still no reliable landmark. To validate the reliability of a novel reference point at the intersection of the inferior border of the cricopharyngeal muscle and the inferior cornu of thyroid cartilage for locating the RLN. Cadaver dissection study in the academic department of otolaryngology-head and neck surgery. Sixty-four RLNs in cadavers were assessed, and measurements of different surgical landmarks in conjunction with the proposed surgical landmark were obtained. Descriptive statistics, Pearson’s chi-squared test, and Student’s t-test were performed to analyze the data using GraphPad Prism (version 9.4.1; Dotmatics, Boston, Massachusetts, USA). The average distance from the proposed landmark to the RLN was 2.3 ± 0.85 mm. The RLN was located just posterior to the reference point in 95.31% of the cadavers. The RLN passed under the inferior constrictor muscle in 90.63% of the cadavers. There was no statistically significant difference between right- and left-sided RLNs in terms of their relation with the reference point. The proposed reference point can be used as a reliable landmark to locate the RLN. This reference point may help surgeons during difficult thyroidectomy surgeries by providing an additional anatomical landmark.

Measurement of Nasal Contour Landmarks in Septorhinoplasties with Special Regard to the Course of Postoperative Swelling Using a Three-Dimensional Camera.

The integration of three-dimensional (3D) cameras into clinical practice for pre-operative planning and post-operative monitoring of rhinoplasties remains controversial. However, this technology offers the advantage of capturing the 3D surface without exposing patients to potentially harmful radiation. Continuous assessment allows the follow-up of swelling patterns, cartilage alignment, and bone remodeling. The primary objective of our study was to quantify changes in nasal structure before and after rhinoplasty by using 3D photography. Our study cohort consisted of 29 patients who underwent open structural rhinoplasty. We used the Artec Space Spider camera to acquire a total of 103 3D images. We collected pre-operative and at least two or three post-operative follow-up scans, which were taken one, three, and six months after surgery. We evaluated paired scans that included various time intervals to improve our understanding of swelling behavior and to ensure an objective analysis of changes. Eleven specific anatomical landmarks were identified for measurement. Two independent raters determined the distances between these landmarks over time. The calculation of intraclass correlation coefficients showed low inter-rater variability. Statistically significant changes over time (p < 0.05) were observed for various anatomical landmarks, including soft tissue nasion, soft tissue orbitale right, soft tissue maxillofrontale left, soft tissue maxillofrontale right, nasal bridge, and nasal break point. Conversely, no significant changes (p > 0.05) were observed in the measurements of soft tissue orbitale left, pronasale, subnasale, alare right, or alare left. A visual assessment was conducted using surface distance maps. The results indicate that the complete decrease in swelling takes at least 6 months or even longer. Additionally, 3D photography can provide an objectively comparable analysis of the face and external contours. Furthermore, it allows for a comparison of external contours and therefore pre- and post-operative differences.

The anterior sylvian point as a reliable landmark for the anterior temporal lobectomy in mesial temporal lobe epilepsy: technical note, case series, and cadaveric dissection.

Mesial temporal lobe epilepsy (MTLE) is one of the most prevalent forms of focal epilepsy in surgical series, particularly among adults. Over the decades, different surgical strategies have been developed to address drug-resistant epilepsy while safeguarding neurological and cognitive functions. Among these strategies, anterior temporal lobectomy (ATL), involving the removal of the temporal pole and mesial temporal structures, has emerged as a widely employed technique. Numerous modifications have been proposed to mitigate the risks associated with aphasia, cognitive issues, and visual field defects. Our approach is elucidated through intraoperative and cadaveric dissections, complemented by neuroradiological and cadaveric measurements of key anatomical landmarks. A retrospective analysis of patients with drug-resistant MTLE who were treated using our ATL technique at IRCCS Neuromed (Pozzilli) is presented. A total of 385 patients were treated with our ATL subpial technique anatomically focused on the anterior Sylvian point (ASyP). The mean FU was 9.9 ± 5.4 years (range 1-24). In total, 84%of patients were free of seizures during the last follow-up, with no permanent neurological deficits. Transient defects were as follows: aphasia in 3% of patients, visual field defects in 2% of patients, hemiparesis in 2% of patients, and cognitive/memory impairments in 0.8% of patients. In cadaveric dissections, the ASyP was found at a mean distance from the temporal pole of 3.4 ± 0.2 cm (range 3-3.8) at the right side and 3.5 ± 0.2 cm (3.2-3.9) at the left side. In neuroimaging, the ASyP resulted anterior to the temporal horn tip in all cases at a mean distance of 3.2 ± 0.3 mm (range 2.7-3.6) at the right side and 3.5 ± 0.4 mm (range 2.8-3.8) at the left side. To the best of our knowledge, this study first introduces the ASyP as a reliable and reproducible cortical landmark to perform the ATL to overcome the patients' variabilities, the risk of Meyer's loop injury, and the bias of intraoperative measurements. Our findings demonstrate that ASyP can be a safe cortical landmark that is useful in MTLE surgery because it is constantly present and is anterior to risky temporal regions such as temporal horn and language networks.

Measurement of Scapholunate Joint Space Width on Real-Time MRI-A Feasibility Study.

The scapholunate interosseous ligament is pivotal for wrist stability, and its impairment can result in instability and joint degeneration. This study explores the application of real-time MRI for dynamic assessment of the scapholunate joint during wrist motion with the objective of determining its diagnostic value in efficacy in contrast to static imaging modalities. Ten healthy participants underwent real-time MRI scans during wrist ab/adduction and fist-clenching maneuvers. Measurements were obtained at proximal, medial, and distal landmarks on both dynamic and static images with statistical analyses conducted to evaluate the reliability of measurements at each landmark and the concordance between dynamic measurements and established static images. Additionally, inter- and intraobserver variabilities were evaluated. Measurements of the medial landmarks demonstrated the closest agreement with static images and exhibited the least scatter. Distal landmark measurements showed a similar level of agreement but with increased scatter. Proximal landmark measurements displayed substantial deviation, which was accompanied by an even greater degree of scatter. Although no significant differences were observed between the ab/adduction and fist-clenching maneuvers, both inter- and intraobserver variabilities were significant across all measurements. This study highlights the potential of real-time MRI in the dynamic assessment of the scapholunate joint particularly at the medial landmark. Despite promising results, challenges such as measurement variability need to be addressed. Standardization and integration with advanced image processing methods could significantly enhance the accuracy and reliability of real-time MRI, paving the way for its clinical implementation in dynamic wrist imaging studies.

Measurements of oculo-palpebral landmarks and evaluation of patient's head position.

Keeping the head in a neutral position is requisite for glasses/lenses/head-up designs, the suitability of oculo-plastic surgery and for the grading the eye shift. Anatomically incompatible glasses are one of the common problems affecting accommodation, reducing comfort and disturbing by causing symptoms such as dizziness and nausea. The oculo-palpebral measurements act as a key determinant in symmetrical facial attractiveness. This study aims to investigate the most effective oculo-palpebral landmarks, head-neutral as the ideal position, taking into account of individual anatomical differences of these patients. 100 females and 100 males aged between 18 and 20 years were photographed. Digital photogrammetric measurements were made with the ImageJ program. Interpupillary and interhelical distances, besides bilateral palpebral fissure length and height, and iris diameter were calculated on front-facing photographs. Mean interpupillary distance was measured wider in males than in females. The mean length of palpebral fissure was 31mm; palpebral fissure height was 10mm. These figures were valid in both eyes and gender. The interhelical distance was calculated as the mean and was measured longer in men. Since the measurement values were the same in both sexes and on both sides, they were determined as important landmarks for controlling the head-neutral position, evaluating whether there was a deviation in the eye, and measuring the numerical value when detected. It is essential to check the side-symmetry of the patient's palpebral fissure height, palpebral fissure length, diameter of iris and corneal depth during oculo-plastic invention and artificial design.

Secondary Repair of Jersey Finger: A Novel Method of Tendon Length Estimation via Measurement of Adjacent Landmarks.

Jerseyfinger describes the rupture of the flexor digitorum profundus (FDP) tendon at its insertion into the distal phalanx. In the absence of an evidence-based approach to tensioning during secondary repair, we aimed to devise a novel method to determine the required tendon length pre/intraoperatively. We measured anatomical landmarks, associated with the FDP tendon, on dissected cadavers, to assess whether these can be used to estimate tendon segment lengths. Eight cadaveric hands were dissected. Three measurements from the distal lumbrical origin to (1) FDP insertion, (2) the distal end of A1 (Annular 1 pulley), and (3) the proximal end of A1 were recorded for digits II-V. Relative ratios for measurement 1were consistent for all digits, compared to digit III. Linear regression analysis confirmed a strong correlation for measurement 1between digit II (R2=0.97) and digit IV(R2=0.97)compared to digit III across all specimens. Digit III distal lumbrical origin to FDP insertion measurements could facilitate the estimation of the required graft length for digit II or IV during secondary repair. This is alevelIV study, providing proofof concept for a novel method of tendon tensioning.

Facial and mandibular landmark tracking with habitual head posture estimation using linear and fiducial markers.

This study compared the accuracy of facial landmark measurements using deep learning-based fiducial marker (FM) and arbitrary width reference (AWR) approaches. It quantitatively analysed mandibular hard and soft tissue lateral excursions and head tilting from consumer camera footage of 37 participants. A custom deep learning system recognised facial landmarks for measuring head tilt and mandibular lateral excursions. Circular fiducial markers (FM) and inter-zygion measurements (AWR) were validated against physical measurements using electrognathography and electronic rulers. Results showed notable differences in lower and mid-face estimations for both FM and AWR compared to physical measurements. The study also demonstrated the comparability of both approaches in assessing lateral movement, though fiducial markers exhibited variability in mid-face and lower face parameter assessments. Regardless of the technique applied, hard tissue movement was typically seen to be 30% less than soft tissue among the participants. Additionally, a significant number of participants consistently displayed a 5 to 10° head tilt.

Template-based target point localization for occlusion of the middle meningeal artery during evacuation of space-occupying chronic subdural hematoma.

Endovascular middle meningeal artery (MMA) occlusion may help reduce the risk of recurrence after burr hole evacuation of chronic subdural hematoma (cSDH) but carries an additional periprocedural risk and remains hampered by logistical and financial requirements. In this study, the authors aimed to describe a simple and fast technique for preoperative MMA localization to permit burr hole cSDH evacuation and MMA occlusion through the same burr hole. The authors performed a preclinical anatomical and prospective clinical study, followed by a retrospective feasibility analysis. An anatomical cadaver study with 33 adult human skulls (66 hemispheres) was used to localize a suitable frontal target point above the pterion, where the MMA can be accessed via burr hole trephination. Based on anatomical landmark measurements, the authors designed a template for projected localization of this target point onto the skin. Next, the validity of the template was tested using image guidance in 10 consecutive patients undergoing elective pterional craniotomy, and the feasibility of the target point localization for cSDH accessibility was determined based on hematoma localization in 237 patients who were treated for a space-occupying cSDH in the authors' department between 2014 and 2018. In the anatomical study, the mean perpendicular distance from the zygomatic process to the target point in the frontoparietal bone was 4.1 cm (95% CI 4-4.2 cm). The mean length along the upper margin of the zygomatic process from the middle of the external auditory canal to the point of the perpendicular distance was 2.3 cm (95% CI 2.2-2.4 cm). The template designed according to these measurements yielded high agreement between the template-based target point and the proximal MMA groove inside the frontoparietal bone (right 90.9%; left 93.6%). In the clinical validation, we noted a mean distance of 4 mm (95% CI 2.1-5.9 mm) from the template-based target point to the actual MMA localization. The feasibility analysis yielded that 95% of all cSDHs in this cohort would have been accessible by the new frontal burr hole localization. A template-based target point approach for MMA localization may serve as a simple, fast, reliable, and cost-effective technique for surgical evacuation of space-occupying cSDHs with MMA obliteration through the same burr hole in a single setting.

Modern Concepts in Sagittal Curve Measurement: Comparison of Spline-Based and Fixed Landmark Measurements in a Cohort of 1520 Healthy Subjects.

Retrospective multicenter study. Our objective was to compare the spline-based measurement of sagittal spinal curvatures to fixed landmarks in a normative population. Recent research has stressed the importance of considering sagittal curvature in its entirety using a spline reconstruction. To date, no data supports the superiority of this method in comparison to classic measurement methods. Full-spine biplanar radiographs of subjects over 20 years old who had normal radiographs were analyzed. Thoracic kyphosis (TK) and lumbar lordosis (LL) were measured following two modalities: either using predefined landmarks (TK T1T12 , TK T5T12 , and LL L1S1 ) or spline-based measurement (TK Spline and LL spline ). A total of 1520 subjects were included (mean 54yo). The mean difference between TK spline and TK T1T12 was 1.4° and between TK spline and TK T5T12 was 11.7° ( P <0.001). LL spline was significantly larger than LL L1S1 (55° vs . 54°, P<0.001 ). LL spline and LL L1S1 were correlated ( R =0.950, P <0.001). Pelvic incidence had no influence on the difference between LL spline and LL L1S1 ( R =-0.034, P= 0.184). Using LL L1S1 measurements, LL was underestimated in 17% of the cases. The comparison of outlier distributions according to age groups ( P =0.175), sex ( P =0.937), or pelvic incidence groups ( P =0.662) found no difference. There were significantly more outliers in Roussouly type 1 compared with other types (56%, P <0.001). Our results suggest that the use of TK T1T12 and LL L1S1 is acceptable to assess spinal sagittal curvatures. However, TK T5T12 is not accurate for the thoracic curve and should be used with caution. LL L1S1 can be used to accurately assess the lumbar curve, except in Roussouly type 1.

Radiographic Landmark Measurements for the Femoral Footprint of the Medial Patellofemoral Complex May Be Affected by Visible Femoral Shaft Length on Lateral Knee Radiographs

To assess the effect of visible femoral shaft length on the accuracy of radiographic landmarks of the medial patellofemoral complex (MPFC). In 9 cadaveric knees, the MPFC footprint was exposed on the medial femur, and its proximal and distal boundaries were marked. Lateral fluoroscopic images of the knee were assessed in 1-cm length increments, beginning 1 cm proximal to the medial condyle and continuing proximally to 8 cm. The MPFC midpoint was described on each image relative to the posterior cortical line of the femur and a line perpendicular to this line through the proximal margin of the medial condyle. In addition, the MPFC midpoint was assessed relative to a line from the proximal posterior cortex to the midpoint of Blumensaat line. Using the posterior cortical line as a reference, the MPFC radiographic landmark moved anteriorly with decreasing visible femoral shaft on radiographs, particularly at 4 cm and less. However, no proximal-distal change was noted. Linear regression analysis demonstrated a relationship between visible femoral shaft and MPFC position on radiographs (R= 0.461, R2= 0.212, B= -0.636, P < .001). For every centimeter decrease in the visible femoral shaft, the radiographic MPFC footprint moved anteriorly by 0.636 mm. Receiver operating characteristic curve analysis revealed that a minimum of 4 cm of femoral shaft on lateral radiographs is required for accurate MPFC footprint localization (area under the curve= 0.80; sensitivity= 76.7%; specificity= 69.0%; P < .001). In contrast, no anterior-posterior change was seen when referencing a line from the proximal posterior cortex to the midpoint of Blumensaat line. When using the posterior cortical line to identify the midpoint of the MPFC, at least 4 cm of femoral shaft should be visible for accurate assessment. If less than 4 cm of shaft is visible, a line through the midpoint of Blumensaat line and the proximal posterior cortex can be used as an alternative method to estimate the position of the femoral footprint. As fluoroscopy is frequently used intraoperatively for MPFC reconstruction, our findings may serve as a guide when assessing femoral tunnel placement on fluoroscopy.

Morphometric Analyses of the Angular Roughshark, Oxynotus centrina (Oxynotidae), with Biological Notes on Specimens from the Sea of Marmara

Morphometric measurements as percentages of total length of 6 specimens of Oxynotus centrina (Linnaeus, 1758), captured in the Sea of Marmara were reported. All of the analyzed proportions of landmark measurements as percentage of total length show allometry. Although, slight differences were seen between the morphometrics of Marmara specimens of O. centrina and those reported for the angular roughsharks captured in several geographical subregions of the Mediterranean Sea, these variations can be considered admissible based on allopatry. Regarding the mouth morphology in particular, the proportion of head length/mouth width to total length showed negative allometry, indicating O. centrina is a small-mouthed shark compared to increasing body size. A partly digested shark embryon and vitellus like slurry were found in the stomach content of one specimen captured in the Sea of Marmara, which provided supporting evidence for the predation on elasmobranch eggs by O. centrina in the wild.

Female Abdominal Landmarks and Their Improvements Using Polydioxanone Thread Placement for Umbilicus Elevation.

Different landmarks on the abdomen have been used to evaluate abdominal aesthetics. However, because researchers use different methods for landmark measurements, there is no consensus as to which landmarks to use for either assessing abdominal aesthetics or guiding surgical planning. Female model photographs were analyzed for abdominal aesthetics with the umbilicus as the key dividing point. Because of the limitation on the number of landmarks that could be shown with model photographs, abdominal landmarks on actual female patients were studied. The variations of landmark metrics due to positional changes and before/after our polydioxanone (PDO)-assisted high-definition liposuctions were recorded. For model photographs, the abdominal apex to mid-umbilicus distance (AU) versus midumbilicus to lower abdominal skin crease (UC) ratio was 1.626. Almost all bony landmarks demonstrated significant caudal shift when switched from standing to supine positions. Meanwhile, other landmarks also underwent substantial changes. This provides evidence that metrics taken in different positions cannot be compared with one another. As expected, after umbilici were elevated with our special technique, the relevant metrics improved postoperatively, with results close to being ideal. However, marked deviations from the mean measured values do exist. Abdominal landmarks change with positional adjustment. In standing position, many landmarks can be used for assessment of abdominal aesthetics. Ideally, efforts should be made such that the final AU/UC is close to 1.618, and XU/UP and UIC close to ideal, for satisfactory surgical results. Nevertheless, in actual practice, umbilicus positions can be varied to accomplish desired goals.

MRI Modeling for 3D Printed Fabrication of Nasoalveolar Molding Appliance in Patients With Cleft Lip and Palate

Purpose: Present a novel technique for fabrication of nasoalveolar molding (NAM) appliances for neonates with cleft lip and palate (CLP) using magnetic resonance imaging (MRI). Study design: Proof-of-concept study. Setting/Participants: One patient with unilateral CLP was recruited for participation in this study at our institution. Interventions: This study employed 2 different methods for creating a NAM appliance, which is used in patients with CLP to improve anatomic positioning of the orofacial cleft in preparation for primary cheiloplasty. The patient underwent intraoral impression for traditional fabrication of a NAM appliance (PMMA-NAM) and also MRI of the face for digital fabrication of a NAM appliance (CAD-NAM). The 2 appliances were then compared using landmarks for measurements. Primary Outcome: Landmark measurements on NAM appliances; Clinical interchangeability of NAM appliances. Results: There was a statistically significant difference in the external arch width between the CAD-NAM and the PMMA-NAM. All other NAM measurements were statistically similar. Additionally, there was clinical success in the interchangeable fit of both appliances on both models. Conclusions: This technique could potentially eliminate the need for creation of an intraoral impression, as well as the adverse events associated with this, in the fabrication of NAM appliances. Larger studies are necessary to further define the efficacy of this novel approach and generalizability to other patients with CLP.

Determination of Appropriate Umbilicus Position during Abdominoplasty in Male Patients.

Abdominoplasty techniques are well documented. The ideal position of the umbilicus has, however, received limited attention. Unfortunately, umbilicus position is not universally agreed upon in male cosmetic abdominoplasty. This study was conducted to determine the ideal umbilicus anthropometric measurements in young men, and the relationships between umbilical position and anterior trunk and torso reference points that may be applicable to intraoperative positioning. It is aimed also at investigating whether umbilicus position would be more accurately determined by considering nipple position instead of the abdominal crease, as recently proposed. Several anthropometric measurements of various anterior abdominal and thoracic landmarks were conducted on 60 young and middle-aged male volunteers and 30 cadavers at São Paulo city. All statistical analysis was completed using Stata software. Of all the measured reference points, a much stronger correlation (0.513) was demonstrated between umbilicus-anterior axillary fold (U-AX) and inter-nipple (N-N) distances with a constant golden number ratio relationship (N-N = U-AX × 0.618) compared with the weak correlation of 0.034 between umbilicus-xiphisternum and umbilicus-abdominal crease. In 75% of volunteers, the calculated U-AX was within ±3 cm of actual measurement, and in 33.33% within ±1 cm. U-AX = 1.618 × N-N equation is more predictive of adequate umbilicus repositioning during abdominoplasty in male patients. Chest and abdomen of men are a single aesthetic unit. Proper positioning of the nipples and umbilicus, as well as harmonious abdominal and torso proportions are critical for an optimal final aesthetic outcome.

Midface hypoplasia in syndromic craniosynostosis: predicting craniofacial growth via a novel regression model from anatomical morphometric analysis

Midface hypoplasia in syndromic craniosynostosis (SC) may lead to serious respiratory issues. The aim of this study was to analyse the morphometric correlation between midface and cranial base parameters in paediatric SC patients in order to formulate predictive regression models. The computed tomography scans of 18 SC patients and 20 control were imported into Materialise Mimics Medical version 21.0 software for the measurement of multiple craniofacial landmarks and correlation analysis. The results showed a strong correlation of anterior cranial base (SN), posterior cranial base (SBa), and total cranial base (NBa) (r = 0.935) to maxilla length and width (ZMR–ZML) (r = 0.864). The model of NBa = − 1.554 + 1.021(SN) + 0.753(SBa) with R2 = 0.875 is proposed to demonstrate the development of the cranial base that causes a certain degree of midface hypoplasia in SC patients. The formula is supported using a prediction model of ZMR–ZML = 5.762 + 0.920(NBa), with R2 = 0.746. The mean absolute difference and standard deviation between the predicted and true NBa and ZMR–ZML were 2.08 ± 1.50 mm and 3.11 ± 2.32 mm, respectively. The skeletal growth estimation models provide valuable foundation for further analysis and potential clinical application.

Using a structured light scanner to evaluate 3-dimensional soft-tissue changes after extracting 4 premolars in young adult female patients

Facial esthetics have always received much attention in orthodontic treatment, especially in young adult female patients. Three-dimensional (3D) soft-tissue changes after orthodontic extraction have not been fully explained. This study evaluated the 3D morphologic changes after orthodontic extraction in young female patients using a structured light scanner. Forty-five adult female patients aged 20-25 years were enrolled in our study. The treatment group consisted of patients who received orthodontic treatment with 4 premolar extractions, and the control group was composed of young female volunteers who had not undergone any orthodontic treatment. To monitor the soft-tissue changes, 9 morphologic regions and 12 landmarks were identified for the 3D deviation analyses. The spatial deviations of landmarks and regions in the x, y, and z directions were constructed for quantitative analysis. Color map images were constructed to visualize soft-tissue displacement as a qualitative evaluation. The paired sample test was used to compare differences at the beginning of the experiment (T0) and after 24 months (T1) in both groups. An independent t test with Bonferroni correction was performed to compare differences between the treatment and control groups. A linear regression test was performed between incisor retraction and changes in the perioral tissues. Subtracting the effect of aging from the lip changes in the control group, the treatment group showed a statistically significant difference in the displacement of labrale superius (-1.37 mm), labrale inferius (-1.89 mm), the upper lip region (-0.98 mm), and the lower lip region (-1.36 mm) along the z-axis. No significant differences were found between the treatment and control groups in the temporal, parotideomasseteric, and buccal regions. Pearson correlation tests indicated a positive correlation between incisor tip retraction and changes in soft tissues (two-dimensional cephalometric analysis, 3D landmark measurements, and 3D regional measurements). The correlation coefficient ranged between 0.45 and 0.55. Three-dimensional soft-tissue changes were mainly concentrated in the upper and lower lip regions in adult female patients after the 4 premolars were extracted. For female patients aged 20-25 years with 4 extracted premolars, soft-tissue changes in the temporal, parotideomasseteric, and buccal regions were not clinically significant.

Angular and linear velocity observer design using vector and landmark measurements

AbstractThis paper presents an approach for designing angular and linear velocity observers for rigid bodies using two inertial vectors and one landmark measurements directly. Compared with the classical velocity estimation algorithms, the proposed observer does not need to reconstruct the pose information from measurements nor be coupled with velocity sensors. The linear‐time varying dynamics of the estimation error equation are analyzed, rigorously showing the uniform local exponential stability of the observer. Simulations are conducted to illustrate the significant performance of the proposed method.