Structural Anatomy

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    The Craniofacial Phenotype in a Mouse Model of Osteogenesis Imperfecta
    (2018-03-15) Menegaz, Rachel A.; Ladd, Summer
    Purpose: Osteogenesis Imperfecta (OI, or “brittle bone disease”) is a rare disorder that is caused by genetic point mutations (COL1A1/COL1A2) that affect type 1 collagen. In OI type III (severe) patients, limb bones are more susceptible to skeletal fractures and the bones of the craniofacial region are underdeveloped. Some OI type III patients also suffer from dental malocclusions or fractures (dentinogenesis imperfecta). The goal of this project is to describe the facial phenotype in an OI mouse model, to see if this model can be used to test potential behavioral and pharmaceutical interventions. Methods: The homozygous OI murine (OIM-/-), a mouse strain with a nonlethal recessively inherited mutation of the COL1A2 gene, is a potential model for the human OI type III. OIM-/- and wild type (WT) littermates were raised from weaning (21 days) to adulthood (16 weeks). Digital 3D craniofacial landmarks were taken from in-vivo micro CT scans, and Kuskal-Wallis ANOVAs (α=0.05) were used to compare centroid size and interlandmark distances between genotypes. Results: Adult OIM-/- mice were found to have decreased cranial and mandibular centroid sizes, compared to WT mice. OIM-/- mice also show several morphological similarities to the OI type III human phenotype, such as shortened basicrania, facial hypoplasia, and altered dental spacing. Conclusions: We conclude that this mouse model shows potential for future investigations of the growth mechanisms underlying the craniofacial presentation of OI. Subsequently, we will next explore the possibility of using increased masticatory loading during the early growth period to stimulate craniofacial bone growth and improve bone quality in the OIM mouse model.
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    Establishing Experimental Sample Uniformity Prior to Patella Component Fixation Testing
    (2018-03-14) Wagner, Russell; Kosmopoulos, Victor; Beck, Cameron; Hogsett, Cameron; Nestlerode, Christina; Nwannunu, Brian
    Purpose: It is imperative to perform quality control studies to validate experimental sample quality prior to testing. Due to the inherent inconsistency when using cadaveric bone as a means to test clinically relevant hypotheses, one such quality check is to geometrically study the variability present in the bone samples. Thus, as a quality control step prior to investing resources to undertake the overall aim of studying patella component fixation in total knee arthroplasty (TKA), this study aims to establish sample uniformity by analyzing patella length, width, and depth. Methods: Ten random pairs of patellae were harvested from a possible 39 embalmed cadavers. Each patella was then prepared by an orthopaedic surgeon, as if performing an intraoperative TKA, for fixation of a patella implant component. After preparation but before adding a patellar component and cement, the surgeon visually inspected each patella and separated each pair with the better bone quality sample as part of the control group and the other as part of the treatment group. Measurements were then taken by two independent observers using a caliper to determine the superior-inferior patellar length (SIL), medial-lateral width (MLW), and the sectioned patellar thickness (TH). T-tests were performed to establish interobserver measurement reliability and the geometric uniformity between the control and treatment groups and between the left and right samples. Results: There was no significant difference between readers in the SIL (p=0.48), MLW (p=0.58) and TH (p=0.23) measurements. No significant differences were found when comparing between the control and experimental groups for any of the three measures (SIL p=0.21, MLW p=0.44, TH p=0.90). There was however, a significant difference observed in the sectioned preparation TH (p=0.007) when comparing left and right knee patellae. Conclusions: Based on the geometric outcomes measured (SIL, MLW, TH) the results of this study validate the sample uniformity when comparing patellae based on control and treatment groups rather than right verses left. Doing so helps control sample quality for completing the overall aim to study cement fixation methods of the patellar component in TKA.
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    Variation of Median Nerve Pathway Around the Elbow Joint
    (2018-03-14) Reyes, Aubrie; Francis, Alex; Liu, Howe; Wohleb, Evan
    Introduction The median nerve is one of the large terminal branches originating from the brachial plexus. It provides the motor innervations to both the forearm and palmar hand, as well as most of the sensory innervation for the palmar hand. On the way to its targeted areas, the median nerve pathway from the upper arm to the hand may pass through some muscles and other accessory structures that may not be considered normal, particularly around the elbow area. The purpose of this study was to trace and observe how this nerve travels in terms of the relationship with surrounding structures proximally and distally to the elbow. Methods Twelve upper extremities from six cadavers (3 males and 3 females) were dissected to trace and observe how the median nerve travels in these specimens. The focused area was from the middle upper arm to the proximal 1/3 of the forearm. Results All twelve identified median nerves passed between the biceps brachii and brachialis muscles. In ten out of the twelve specimens, about two to three fingers width proximal to the elbow joint line between the medial and lateral epicondyles of the humerus, it was found that the median nerve surfaced from the inferomedial edge of the biceps muscle and continued traveling down under a tight bicep aponeurosis and then pierced into the pronator teres muscle - common impingement areas for the median nerve. After we reflected the biceps muscle laterally from the remaining two of the twelve left forearms to expose the median nerve, it was observed that the nerve pierced through the brachialis muscle at its superior border (three to four fingers width proximal to the joint line), which was a very interesting finding. The nerve exited from the inferior border of the muscle, continued to pass down for one to two fingers width, and pierced the pronator teres as did the other ten median nerves. Conclusion Observing two of twelve specimens, the median nerve showed a different pathway around the elbow joint, which is abnormal from others’. Namely, the nerve pierces through the brachialis muscle before descending and passing through the pronator teres muscle. Clinical Implication Such a variation of the median nerve pathway has not been reported before. This finding may offer clinicians an additional explanation of the median nerve impingement-related clinical symptoms that are very similar to the pronator teres syndrome.
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    Bronchopulmonary Variation in a Case of Situs Inversus Totalis
    (2018-03-14) Fisher, Cara; Blackwood, Taylor
    Abstract Background: Situs inversus totalis is the transposition of thoracic and abdominal internal organs across the sagittal plane. The incidence of situs inversus totalis is 1:10,000. This case of situs inversus totalis had variant bronchopulmonary laterality. Through extensive literature review we report no other documented cases of individuals with this anatomical variation. Case Information: This study involved detailed dissection of a 71-year-old male with situs inversus totalis and variant bronchopulmonary structures. This study serves to add to the expanding body of knowledge of situs inversus totalis and variations from the expected laterality. In the expected anatomy of individuals with situs inversus totalis, the right lung is bi-lobed and the left lung is tri-lobed. However, this case is exceedingly rare in that the individual maintained a tri-lobed right lung and bi-lobed left lung. In contrast to this, the cadaver maintained the expected situs inversus laterality of both hilar structures. The cadavers tri-lobed right lung maintained the pulmonary artery superior to the primary bronchus while the cadavers bi-lobed left lung possessed the pulmonary artery anterior to the primary bronchus. All other visceral findings were consistent with the expected laterality. Conclusions: As the cadaver maintained expected laterality of the bronchi and pulmonary arteries but did not maintain expected lung structure, we suggest that these findings may assist current research in determining the specific point in embryological development that laterality is determined. Clinicians, surgeons and radiologists should be aware of situs inversus totalis for diagnostic and therapeutic procedures and current clinical guidelines should take these rare variations into consideration.
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    (2018-03-14) Dhume, Mahima; Fisher, Cara; Reeves, Rustin; Farrell, Molly
    Background: A hiatal hernia describes a herniation of abdominal contents, typically the stomach, through the esophageal hiatus into the mediastinum. The majority of reported paraesophageal hernias (PEH) are left-sided; although, right-sided hiatal hernias have a better prognosis, there is little mention of them in current literature. Case Information: During a routine cadaver dissection for academic purposes, a massive hiatal hernia was identified in an 84-year-old female. This anatomic variant case presents with the abdominal contents of the entire stomach, pyloric sphincter, and portions of the greater and lesser omentums displaced into the right thoracic cavity. Such hernias can have acute symptoms, chronic symptoms, or present as asymptomatic. In this case report, the donor was thought to have no significant functional abnormalities, although there were reports of gastrointestinal bleeding. Conclusions: We believe this case to be a rare variant due to two factors: the size of the hiatus, and the displacement of the hernia into the right side of the mediastinum. The hiatal surface area (HSA) in this case report was calculated to be 17.41cm2, which is almost three times the established average HSA in normal patients. This case report attempts to add to the body of literature detailing right-sided hiatal hernias. Looking forward, we believe that there is great scope for future research specific to right-sided hiatal hernias and improvement in the quality of life for those who undergo elective PEH repair.
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    Sexual Dimorphism in the Trochlear Angle of the Humerus: A preliminary investigation in Hunter-Gatherers and Agriculturalists
    (2018-03-14) Maddux, Scott D.; Pennavaria, Alexa
    Purpose: Previous research has argued the elbow “carrying angle” to be sexually dimorphic in humans, with females exhibiting greater abduction of the supinated forearm at full extension. Moreover, it is generally assumed that the trochlear angle of the humerus is the primary skeletal basis of the carrying angle, and thus, may independently provide a reliable osteological indicator of sex in forensic, bioarchaeological, and paleoanthropological contexts. Methods: Here, we employed the software TPSDig2 to derive trochlear angles from photographs of humeri collected on 40 (17 female/23 male) adult Archaic-period Amerindian hunter-gatherers and 54 (24 female/30 male) adult Medieval European agriculturalists. Due to handedness, angles from left and right humeri were averaged for each individual, with asymmetry assessed by subtracting the more acute angle from the more obtuse angle irrespective of actual left/right siding. Results: Although based on small sample sizes, males and females were not found to be significantly different from each other in either the Amerindian (t=1.5, p=0.13) or European (t=-1.3, p=0.26) samples. With both sexes pooled, the Amerindian sample exhibited more acute trochlear angles (t=4.64, p Conclusions: While failing to support the trochlear angle as a diagnostic sex indicator, our results are consistent with previous research generally demonstrating elevated levels of upper limb asymmetry in hunter-gatherer populations — asymmetries typically attributed to reliance on activities requiring greater unilateral loading of the dominant limb. Accordingly, the results of this study may indicate that more acute trochlear angles (less forearm abduction) reflect higher levels of biomechanical loading. Thus, sexual dimorphism in the carrying angle, if/when present, may be dependent on sex-specific activity patterns.
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    Validating the Pig ACL as a Model for Pre-Clinical Testing of Ligament Repair Techniques
    (2018-03-14) Kosmopoulos, Victor; Singleton, Steven; Homewood, Tyler
    Purpose: Advancements in surgical repair and reconstruction of the anterior cruciate ligament (ACL) necessitate an appropriate animal model for pre-clinical testing. Furthermore, pre-clinical testing using cadaveric tissue is less readily available and comes at a greater cost as compared to animal tissue. Although the literature suggests the use of a pig model as a good biomechanical alternative for knee joint studies, only a limited number of studies have investigated similarities in knee joint anatomy. This study specifically aims to establish a method for comparing the geometric length, width and thickness of the ACL between humans and pigs in an effort to provide a measurement of proportionality between the two. Although the pig ACL may be smaller in overall size, we hypothesize that the dimensions will be proportional. Developing a repeatable measurement method and understanding geometric differences can help in study design (e.g., selecting suture size for ligament repair), control for experimental variation, and adds to our understanding of the mechanical differences that may be observed during testing. Although this is a preliminary study, future studies expanding this work will help determine if the pig is an appropriate alternative. Projecting ahead, as these examinations advance into in vivo studies, a validated pig model can serve as a way to follow long-term outcomes. Methods: Multi-planar digital images were acquired of a sectioned anterior cruciate ligament (ACL) from both a juvenile Yorkshire pig and a 78 year old male cadaver. Each image was imported and calibrated using imageJ (1.49v, National Institutes of Health, USA). Measurements were taken by two independent observers to determine ACL length, width, and thickness for comparison between human and pig ACL dimensions. A paired t-test was performed to establish inter-observer image measurement reliability (alpha=0.05). Results: No significant difference between readers was found in the ACL dimensions measured (p=0.23). The pig ACL had a length of 25.9-mm, a width of 10.6-mm, and a thickness of 4.1-mm. The length and thickness of the pig ACL were both 24% smaller than the human ACL. The width however did not match the scaling factor found in the other two dimensions resulting in only a 14% decrease as compared to the human ACL. Conclusions: This preliminary study establishes a reliable method for measurement of ligament dimensions. Although limited in sample size, the comparison between the ACL of a Yorkshire pig and a human was found to be proportional in two of the three dimensions studied. Moreover, visual comparison showed the ligaments to have very similar planar geometries. The study is currently ongoing and more samples are being collected and analyzed. Such geometric information will help add to our understanding of the ACL as a structure and add to the biomechanical tissue data available in the literature. Moving forward, we hope to use the pig as a model to study two novel ACL repair techniques.
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    Thermoregulation and the Human Nose: Balancing Climatic and Energetic Factors
    (2018-03-14) Maddux, Scott D.; Kim, Suhhyun
    Purpose: Studies have shown that indigenous individuals from cold-dry climates exhibit longer, taller, and especially narrower nasal passages compared to equatorial counterparts, enhancing inspiratory air-conditioning (heating and moisturizing) capacity and reducing susceptibility to respiratory tract infections. Concurrently, due to increased demand for thermogenesis, cold-dry climates are also metabolically more expensive than tropical environments, necessitating greater volumetric intake of oxygen. Accordingly, recent research has suggested that while a narrower nose enhances inspiratory air-conditioning, the accompanying restriction on volumetric intake may necessitate increased nasal height to maintain sufficient intake of oxygen. The purpose of this study was to examine the relationship between nasal dimensions, climate, and the metabolic demands. Methods: We employed 12 linear measurements collected from the nasal skeleton of 837 modern human crania from major geographic (Arctic Circle, Asia, Australia, Europe, Africa) and climatic (polar, temperate, hot-arid, tropical) zones. Anterior-posterior femoral head diameter (FHD) was further employed as a proxy for overall body size and metabolic requirements. Morphological, climatic, and geographic data were then employed in multivariate analyses. Results: Our results indicate that most breadth measurements of the nasal aperture and internal cavity are significantly correlated with climate (all significant R2 values between 0.29–0.51 with p-values 2 values between 0.67–0.78 with p-values 2 values between 0.36–0.56 with p-values 2 = 0.67, p = 0.0003), while nasal passage shape retained a significant relationship with climate (R2 = 0.66, p = 0.0004) with relatively tall/narrow airways associated with colder-drier environments. Conclusion: Collectively, these results support the assertion that physiological demands for temperature and moisture exchange are predominantly mediated by nasal passage breadth, with airway height representing a compensatory mechanism for ensuring a metabolically sufficient oxygen intake. Additional studies employing more direct measures of metabolic demands are accordingly warranted.
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    Surface projection of the posterior interosseous nerve and artery as they exit the supinator and interosseous foramen respectively : A cadaver study
    (2018-03-14) Hart, Keaton; Mincy, Missy; Liu, Howe; Arguello, Eric; Tran, Huy
    Purpose: The purpose of this study was to develop a method for locating surface projections of the posterior interosseous nerve (PIN) and posterior interosseous artery (PIA) as they exit the supinator muscle and interosseous foramen respectively. Methods: Distances from the vertical and transverse planes through the lateral epicondyle of the humerus to the exit point of the PIN through the supinator and the PIA through the interosseous foramen were measured on 10 upper extremities from 5 cadavers. Average distances were used to find coefficients in terms of the thumb interphalangeal joint widths. Results: The mean transverse plane distance from the lateral epicondyle to the exit points of the PIN and PIA were 79.38 mm (~4.0 IPJ widths) and 90.62 mm (~4.5 IPJ widths) respectively. The mean vertical plane distance from the radius to the exit points of the PIN and PIA were 9.45 mm (~0.5 IPJ widths) and 10.86 mm (~0.5 IPJ widths) respectively. Conclusions: The results of this study present a method to assist clinicians in avoidance of iatrogenic outcomes with the application of various treatments such as dry needling and acupuncture.
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    Diagnostic Validation of Dynamic Ultrasound Evaluation of Supination-External Rotation Ankle Injuries
    (2018-03-14) Fisher, Cara; Johnson, Katelyn; Reeves, Rustin; Wood, Addison; Rabbani, Tebyan
    Abstract Purpose: Definitive diagnosis of syndesmosis injuries can be made with plain film radiographs if the injury is severe enough, but often is missed when severity or image quality is low. Ultrasound diagnosis may circumvent many of these disadvantages by being inexpensive, efficient, and able to detect subtle injuries without radiation exposure. This study evaluates the ability of ultrasound to detect subtle SER ankle syndesmosis injuries with a dynamic external rotational stress test. Methods: Nine male fresh frozen specimens were secured to an ankle rig and stress tested to 10 Nm of external rotational torque with ultrasound monitoring at the tibiofibular clear space. The ankles were subjected to syndesmosis ligament sectioning and repeat stress measurements of the tibiofibular clear space at peak torque. Ankle States Examined: 1. Intact State 2. 75% of AITFL Cut 3. 100% of AITFL Cut 4. Fibula Fx - Cut 8 cm proximal 5. 75% PITFL Cut 6. 100% PITFL Cut Results: Dynamic external rotation stress evaluation using ultrasound was able to detect a significant difference between the uninjured ankle tibiofibular clear space of 4.5 mm and the injured ankle with 100% of anterior inferior tibiofibular ligament cut 6.0 mm (P=.017). Additionally, this method was able to detect significant differences between the uninjured ankle and the injured states. Conclusion: Dynamic external rotational stress evaluation using ultrasound was able to detect stage 1 Lauge-Hansen SER injuries with statistical significance and corroborates criteria for diagnosing a syndesmosis injury at ≥ 6.0 mm of tibiofibular clear space widening.
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    Variation of Posterior Deltoid Muscle
    (2018-03-14) Fisher, Cara; Reeves, Rustin; Baillio, Michael
    Background: Shoulder anatomy develops into a complex structure with some of the widest ranges of motion displayed on the human body. Held together entirely by ligaments and muscles, the shoulder a relatively weak joint with many clinical presentations. An overlooked attribute is the anatomic variability within the shoulder region. During a routine dissection, bilateral posterior variants of the deltoid muscle, with an interesting orientation of muscle fibers, were discovered on a 78-year-old female cadaver. These variants show an almost perpendicular orientation to the expected direction of deltoid muscle fibers and are not consistent with any other expected muscle bellies in the region. Case Information: While performing a routine dissection in the gross anatomy laboratory, aberrant deltoid muscle straps were observed bilaterally on a 78-year-old female cadaver. These fibers, seen in the figures below, extend superficially from the lateral aspect of the overlying deltoid and lateral triceps brachii fascias. These fibers then lay on top of the infraspinatus muscle belly. Directionally they run at a perpendicular angle to the posterior deltoid fibers and are contained within a separate fascial sheath lying superficially over the existing muscle bellies. An additional, albeit rather small, set of fibers run from the same deep deltoid and triceps brachii fascias to then lay over the scapular spine origin of the posterior deltoid. Although these fibers are contained within a separate fascial sheath, there appears to be no change in the neurovascular anatomy associated with the posterior shoulder. A separate neurovascular bundle was not noted to accompany either of the variant muscle straps. Conclusions: Aberrant straps of muscle in the deltoid region have been described on several occasions. The shoulder joint is an unstable joint with one of the widest ranges of motion of any joint in the body. Its mobility is derived from the construction of the capsule, which is composed of a network of tendon and connective tissue. Consequently, this joint is the source of a great number of acute and chronic pain cases. Perhaps a portion of these cases may be attributed to the presence of variant muscles influencing the shoulder joint. In addition to pain, the shoulder is a frequent location for a variety of surgical procedures. Effective clinical management of patients with concerning shoulder issues should include consideration of atypical structures, whether intra-operatively or not.