Computerized tomography based 3D modeling of the clavicle

Sex differences in workload in medieval Poland: Patterns of asymmetry and biomechanical adaptation in the upper limb at Giecz

OBJECTIVES

This study characterizes sexual dimorphism in skeletal markers of upper limb mechanical loading due to lateralization as evidence of division of labor in medieval Giecz, Poland.

METHODS

Twenty-six dimensions for paired humeri, clavicles, and radii representing adult males (n = 89) and females (n = 53) were collected from a skeletal sample from the cemetery site Gz4. Percent directional asymmetry (DA) and absolute asymmetry (AA) for each dimension were compared among bones, osteometric subcategories, and sex. Additionally, side bias and sex differences were assessed in degenerative joint disease (DJD) and entheseal changes (ECs).

RESULTS

Nearly all measurements revealed significant asymmetry favoring the right side. Asymmetry was most pronounced in midshaft dimensions with few sex differences. There were more correlations among dimensions within elements than between elements, mainly in the midshaft. No laterality in DJD frequencies was noted for either sex, but females demonstrated significantly lower odds of having DJD than males in most joints. Most ECs demonstrated a right-bias and association with DA with no sex-specific patterns except the biceps brachii insertion, where females were ~5 times more likely to be scored "right" than males.

DISCUSSION

The general lack of sex differences in asymmetry and ECs suggests similarly demanding workloads for females and males, with the exception of sex-specific functional loading differences in the forearm. Further, DJD data suggest males engaged in more intensive activities involving the upper limb. These results enhance understanding of workload in this important historical period and provide a comparison for asymmetry in past populations.

Thin patient-specific clavicle fracture fixation plates can mechanically outperform commercial plates: An in silico approach

Current fixation plates used to operatively stabilize clavicular fractures are suboptimal, leading to reoperation rates up to 53%. Plate irritation, which can be caused by a poor geometric fit and plate thickness, has been found to be an important factor for reoperation. Moreover, muscle attachment sites (MAS) have to be detached occasionally. To improve current surgical clavicle fracture treatment with plate osteosynthesis, a change in plate design is required. The goal of this study was to design a patient-specific clavicle fracture fixation plate that includes geometrical optimization and stiffness determination. Its biomechanical performance has been compared with a commercial plate by examining the geometric fit, anatomical outline, stresses and interfragmentary motion using a finite element analysis with physiological loading and boundary conditions. Evaluation showed a better geometrical fit of the patient-specific plate as well as an improved fracture reduction. Displacements between fracture fragments were lower in case of the patient-specific plate, both when a fracture gap and no fracture gap were present. Results indicate a superior mechanical performance in terms of all investigated outcomes of the patient-specific plate compared to the commercial plate, while better aligning with the patient-specific geometry and without the need for MAS release. Due to the patient-specific geometry and reduced thickness, these fixation plates are expected to decrease the operation time, as intraoperative contouring will become irrelevant, and to decrease reoperation rates as implant irritation will be minimized.

Conoid tubercle angle: attention should be paid to supraclavicular plate fixation

Background

The surgical protocol of ORIF for the treatment of mid-shaft clavicle fractures is common. However, poor plate fit or overhang usually occurs when the straight plate is selected for superior fixation. This is because the upper edge of the clavicle is not flat but has an angulation near the conoid tubercle. We termed that angulation, conoid tubercle angle (CTA). Supposed the straight plate is forcibly attached to the surface of the clavicle, it will potentially cause misalignment of the fracture end and with that comes a change of CTA. In this case, choosing the contoured plate, such as a commercial pre-contoured anatomic plate or manual-contoured plate, for superior fixation seems to meet the requirements for both plate fit and fracture alignment. Hence, we retrospectively compared the radiological parameters, including the plate overhang, and the alignment of the fractures reflected by the CTA, between the contoured plate (CP) and straight plate (SP) groups, to draw attention to the CTA and its effects to supraclavicular plate fixation.

Methods

From March 2018 to April 2021, 217 patients with clavicle fractures that met the inclusion criteria but not the exclusion criteria were included in our study. 112 patients were enrolled into the straight plate group (SP) and 105 patients into the contoured plate group (CP). Besides that, 154 healthy adults were recruited into the health group (HA).

Results

Patients were followed up for 6 to 40 months postoperative. A normal CTA (164.54 ± 4.78°) was obtained from the HA group. There were 50 cases with plate overhang in the SP group, which presented a statistical difference in comparison with the CP group. The value of CTA (169.65 ± 5.84°) in the SP group also indicated a statistical difference in comparison with the normal CTA. Subgroup analysis showed that the CTA (165.88 ± 5.42°) in the overhang subgroup (O) had no statistical difference in comparison with the normal CTA, but the CTA (172.68 ± 4.18°) in the non-overhang subgroup (N-O) had. 3 cases experienced non-traumatic re-fracture (within 3 months after the removal of the fixation) in the O subgroup; 10 cases experienced a poor reduction in the N-O subgroup. In the CP group, the CTA was 166.79 ± 5.68°, which indicated a statistical difference with the SP group. Subgroup analysis was performed, including the manual-contoured plate subgroup (M-C) and commercial pre-contoured anatomic plate subgroup (P-C). The value of CTA (M-C, 166.97 ± 6.33°; P-C, 166.44 ± 6.33°) manifested a statistical difference in comparison with the N-O subgroup. 2 and 8 cases, respectively, had screw loosening and poor reduction in the M-C subgroup. No postoperative complication occurred in the P-C subgroup.

Conclusion

CTA is a useful reference in the evaluation of the reduction obtained on radiographic examination, and a reference guiding the plate contouring. The commercial pre-contoured anatomic plate provides a normal CTA and well fits the biomechanical characteristics of the clavicle, which can be recommended for superior fixation.

Exploring the Functionality of Mesh-to-Mesh Value Comparison in Pair-Matching and Its Application to Fragmentary Remains

Simple Summary

Forensic anthropologists often face the task of analysing a mixed group of skeletal remains or matching a solitary bone with the rest of a skeleton to determine if it belongs to the same individual. One of the best ways to do this is by pair-matching left and right bones of the same type. Common pair-matching methods experience issues such as high levels of subjectivity, lack of reliability, or expensive cost of implementation. This study explores the application of the relatively new method, mesh-to-mesh value comparison (MVC), which matches paired bones based on morphological shape to determine the likelihood that they derive from the same individual. This study sought to expand on the success found in past publications using MVC and to see how well it performed on a sample of clavicles, a bone known for having a high degree of bilateral variability, of 80 modern Turkish individuals. This study also explored whether MVC can reliably match fragmented bones to their intact counterpart. Results show MVC successfully matched 88.8% of paired clavicles and suggest the method continues to be a promising avenue for pair-matching that is not affected by ancestry and may be applicable to fragmented remains with further study.

Abstract

Many cases encountered by forensic anthropologists involve commingled remains or isolated elements. Common methods for analysing these contexts are characterised by limitations such as high degrees of subjectivity, high cost of application, or low proven accuracy. This study sought to test mesh-to-mesh value comparison (MCV), a relatively new method for pair-matching skeletal elements, to validate the claims that the technique is unaffected by age, sex and pathology. The sample consisted of 160 three-dimensional clavicle models created from computed tomography (CT) scans of a contemporary Turkish population. Additionally, this research explored the application of MVC to match fragmented elements to their intact counterparts by creating a sample of 480 simulated fragments, consisting of three different types based on the region of the bone they originate from. For comparing whole clavicles, this resulted in a sensitivity value of 87.6% and specificity of 90.9% using ROC analysis comparing clavicles. For the fragment comparisons, each type was compared to the entire clavicles of the opposite side. The results included a range of sensitivity values from 81.3% to 87.6%. Overall results are promising and the MVC technique seems to be a useful technique for matching paired elements that can be accurately applied to a Modern Turkish sample.

Fracture patterns in midshaft clavicle fractures

Current classifications of midshaft clavicle fractures are based on radiography. The aim of the study was to evaluate the fracture pattern of clavicle fractures using 3-dimensional computed tomography (3D CT). A retrospective analysis was performed on CT scans of 65 acute clavicle fractures. Using quantitative 3D CT reconstruction techniques, the fracture of the clavicle was virtually reduced. Based on these reconstructions, a group-based fracture heat map and small fragment heat map, and the location of the most common fracture line were determined. Also, the direction and amount of displacement were evaluated. Three fracture patterns could be distinguished. The primary fracture line in type 1 is going from posteromedial to anterolateral and located between 50% and 68% of the clavicle’s length. In type 2, a transverse fracture line is located around 55%, and in type 3, a superolateral to inferomedial line is located between 47% and 56%. Wedged fracture fragments can be seen in types 1 and 2 and are mainly situated inferiorly. The displacement is similar in all types, but the main direction of displacement is specific for the different types (posterior, anterior, inferior). We can conclude that several fracture patterns can be seen in clavicle fractures. Most fractures are located laterally at the midshaft of the clavicle. Wedged segments are mainly located inferiorly, and at the posterior part of the clavicle, no comminution is ever seen. The direction of displacement depends on the fracture pattern.

The variance of clavicular surface morphology is predictable: an analysis of dependent and independent metadata variables

Background

The anatomy of the clavicle is specific and varied in reference to its topography and shape. These anatomic characteristics play an important role in the open treatment of clavicle fractures. The complex and variable topography creates challenges for implant placement, contouring, and position. Hardware prominence and irritation does influence the decision for secondary surgical intervention.

Methods

Computerized tomographic scans of 350 adult clavicles with the corresponding patients' metadata were acquired and digitized. Morphologic parameters determining the shape of the clavicle were defined and computed for each digitized bone. The extracted morphologic parameters were correlated with patient metadata to analyze the relationship between morphologic variability and patient characteristics.

Results

The morphologic parameters defining the shape, that is, the radius of the medial and lateral curves, the apparent clavicle height and width, and the clavicle bow position, correlate with the clavicle length. The clavicle length correlates with the patients' height. Gender differences in shape and form were dependent and related to individual height distribution and clavicle length. Asian populations showed a similarly predictable, but shifted, correlation between shape and clavicle length.

Conclusion

This anatomic analysis shows that the clavicle shape can be predicted through the clavicle length and patients' stature. Smaller patients have shorter and more curved clavicles, whereas taller patients have longer and less curved clavicles. This correlation will aid surgeons in fracture reduction, implant curvature selection, and in optimal adaptation of clavicle implants, and represents the basis for anatomically accurate solutions for clavicle osteosynthesis.

Variation of the clavicle's muscle insertion footprints - a cadaveric study

The muscle footprint anatomy of the clavicle is described in various anatomical textbooks but research on the footprint variation is rare. Our goal was to assess the variation and to create a probabilistic atlas of the muscle footprint anatomy. 14 right and left clavicles of anatomical specimens were dissected until only muscle fibers remained. 3D models with muscle footprints were made through CT scanning, laser scanning and photogrammetry. Then, for each side, the mean clavicle was calculated and non-rigidly registered to all other cadaveric bones. Muscle footprints were indicated on the mean left and right clavicle through the 1-to-1 mesh correspondence which is achieved by non-rigid registration. Lastly, 2 probabilistic atlases from the clavicle muscle footprints were generated. There was no statistical significant difference between the surface area (absolute and relative), of the originally dissected muscle footprints, of male and female, and left and right anatomical specimens. Visualization of all muscle footprints on the mean clavicle resulted in 72% (right) and 82% (left) coverage of the surface. The Muscle Insertion Footprint of each specimen covered on average 36.9% of the average right and 37.0% of the average left clavicle. The difference between surface coverage by all MIF and the mean surface coverage, shows that the MIF location varies strongly. From the probabilistic atlas we can conclude that no universal clavicle exists. Therefore, patient-specific clavicle fracture fixation plates should be considered to minimally interfere with the MIF. Therefore, patient-specific clavicle fracture fixation plates which minimally interfere with the footprints should be considered.

Why off-the-shelf clavicle plates rarely fit: anatomic analysis of the clavicle through statistical shape modeling

BACKGROUND

The clavicle presents a large variability in its characterizing sigmoid shape. Prominent and nonproperly fitting fixation plates (FP) cause soft tissue irritation and lead to hardware removal. It is therefore key in FP design to account for shape variations. Statistical shape models (SSMs) have been built to analyze a cluster of complex shapes. The goal of this study was to describe the anatomic variation of the clavicle using SSMs.

METHODS

Two different SSMs of the clavicle were created, and their modes of variation were described. One model contained 120 left male and female clavicles. The other model consisted of 76 left and corresponding right clavicles, 41 originating from men and 35 from women.

RESULTS

The model of 120 left clavicles showed that 10 modes of variation are necessary to explain 95% of the variation. The most important modes of variation are the clavicle length, inferior-superior bow, and medial and lateral curvature. Statistically significant differences between male and female clavicles were seen in length, sigmoid shape, and medial curvature. Comparison in men between left and right revealed significant differences in length and medial curvature. For women, a statistically significant difference between left and right was only seen in the length.

CONCLUSIONS

Although the operative treatment of displaced midshaft clavicular fractures has clear benefits, the variable anatomy of the clavicle often makes it challenging for the surgeon to make the plate fit adequately. Based on the identified variability in the clavicle's anatomy, it seems unlikely that a clavicle plating system can fit the entire population.

3D statistical model of the pelvic ring - a CT-based statistical evaluation of anatomical variation

The pelvic ring is a highly complex construct with a central role for human stability and mobility. The observable interindividual differences in skeletal anatomy are caused by anatomical variation in the innominate bones as well as the sacrum, further to differences in the spatial arrangement of these bones to each other. The aim of this study was to generate a 3D statistical model of the entire pelvic ring in order to analyse the observed interindividual differences and anatomical variation. A series of 50 anonymized pelvic CT scans of uninjured Japanese adults [30 males, 20 females, average age of 74.9 years, standard deviation (SD) 16.9 years] were processed and analysed, resulting in a 3D statistical overall mean model and separate male and female mean models. Principal component analysis (PCA) of the overall statistical model predominantly showed size variation (20.39%) followed by shape variation (14.13%), and a variation of the spatial arrangement of the sacrum to the innominate bones in different anatomical peculiarities (11.39 and 8.85%). In addition, selected internal and external pelvic parameters were manually measured with the objective of further evaluating and quantifying the observed interindividual as well as the known sex-specific differences. A separate statistical model of the grey value distribution based on the given Hounsfield unit (HU) values was calculated for assessing bone mass distribution, thus an indication of bone quality utilizing grey values as a quantitative description of radiodensity was obtained. A consistent pattern of grey value distribution was shown, with the highest grey values observed between the sacro-iliac joint and the acetabulum along the pelvic brim. Low values were present in the sacral ala, in the area of the iliac fossa as well as in the pubic rami next to the symphysis. The present model allows a differentiated analysis of the observed interindividual variation of the pelvic ring and an evaluation of the grey value distribution therein. Besides providing a better understanding of anatomical variation, this model could be also used as a helpful tool for educational purposes, preoperative planning and implant design.

Contrast-enhanced computed tomography combined with Chitosan-Fe3O4 nanoparticles targeting fibroblast growth factor receptor and vascular endothelial growth factor receptor in the screening of early esophageal cancer

Esophageal cancer is a malignant tumor with a relatively high invasiveness, metastatic potential and worldwide incidence among human cancers. The majority of patients with esophageal cancer are diagnosed in a late tumor stage due to a lack of advanced and sensitive protocols for the diagnosis of patients with early-stage esophageal cancer. In the current study, contrast-enhanced computerized tomography (CECT) combined with Chitosan-Fe₃O₄ nanoparticles targeting fibroblast growth factor receptor (FGFR) and vascular endothelial growth factor receptor (VEGFR; CECT-CNFV) were used to diagnose patients with suspected esophageal cancer. A Chitosan-Fe₃O₄-parceled bispecific antibody targeting FGFR and VEGFR was produced and its affinity to esophageal cancer cells was determined both in vitro and in vivo. A total of 320 patients with suspected esophageal cancer were voluntarily recruited to evaluate the efficacy of CECT-CNFV in the diagnosis of early-stage esophageal cancer. All participants were subjected to CT and CECT-CNFV to detect whether tumors were present in the esophageal area. A Chitosan-Fe₃O₄ nanoparticles contrast agent was orally administered at 20 min prior to CT and CECT-CNFV. The results demonstrated that CECT-CNFV improved diagnostic sensitivity and provided a novel protocol for the diagnosis of tumors in patients with suspected gastric cancer at an early-stage. Furthermore, the resolution ratio of images was enhanced by CECT-CNFV, which enabled the visualization of tiny tumor nodules in esophageal tissue. Clinical data demonstrated that CECT-CNFV diagnosed 200 patients with suspected early-stage esophageal cancer and 120 patients as tumor free. In addition, CECT-CNFV exhibited higher signal enhancement of tumor nodules than CT, suggesting a higher accuracy and accumulation of nanoparticle contrast agent within the tumor nodules of esophageal tissue. Notably, the survival rate of patients with esophageal cancer diagnosed at an early-stage by CECT-CNFV was higher than the mean five-year survival rate (P<0.01). In conclusion, CECT-CNFV enhanced the sensitivity and accuracy of CT in the diagnosis of early-stage esophageal cancer. Thus, CECT-CNFV may improve the accuracy of CT in the diagnosis of mural enhancement in patients with esophageal cancer.