Structural Anatomy

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    Extensor Tendon Injury Outcomes Based on Zone of Injury
    (2022) Yousuf, Hayyan; Garcia, Laura; Dalton, Stewart; Pientka, William
    Purpose: Extensor tendons are located on the dorsal surface of the hand, however they lie superficially and are protected only by a thin layer of soft tissue. This makes them vulnerably to injury and morbidity. There are established anatomical zones of the hand which allow surgeons to classify injury locations, and previous studies have explored the link between zone of injury and outcomes following surgery. This has been well studied for the flexor tendons (ventral surface of the hand), but is still poorly characterized for the extensor tendons. In the present study, we aim to determine which zones are more amenable to surgical repair, and what unique factors may impact surgical outcomes for each zone. Methods: We have conducted a retrospective chart review of patients who have undergone extensor tendon repair surgery at JPS Health Network since 2012. Results: Our data collection revealed that zones 1-4 had statistically significant worse final flexion TAM when compared to zones 5-8. Conclusion: Our preliminary data analysis suggests that there is a statistically significant difference in the outcomes of different zones of injury, and therefore each zone deserves unique considerations prior to surgical repair. This is possibly due to the fact that the more proximal zones generally have more complex injury patterns.
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    Additive Effects of Diabetes and Lower-Limb Amputation on Osteoarthritis with Comparison to Diabetic and Healthy Controls
    (2022) Ngo, Wayne; Finnerty, Cait; Finco, MG; Holley, Bethany; Menegaz, Rachel A.
    Purpose: Individuals with type II diabetes and individuals with lower-limb amputation each have increased risks of developing osteoarthritis compared to the general population. Despite the high co-occurrence of type II diabetes with lower-limb amputations, the additive effects of these conditions are unclear. In order to better manage the risk of developing osteoarthritis in these populations, a better understanding of how diabetes and amputation might compound osteoarthritis risk is needed. Methods: We measured hip and knee joint space, as indicators of osteoarthritis, in four groups of individuals: 1) lower-limb amputees with diabetes, 2) lower-limb amputees without diabetes 3) diabetic controls, and 4) healthy controls. We hypothesized lower-limb amputees with diabetes would have the most impaired musculoskeletal health, followed by amputees without diabetes, diabetic controls, then healthy controls. 30 total CT scans of males (42-79 years; BMI 19.7 - 48.9 kg/m2) were obtained from the New Mexico Decedent Image Database. 10 scans were identified for amputees, diabetic controls, and healthy controls. Half of the lower-limb amputees had diabetes while half did not, to differentiate effects of diabetes and amputation on musculoskeletal health. 3D Slicer software was used to measure hip and knee joint spaces as indicators of osteoarthritis. Comparisons between groups were assessed using Kruskal-Wallis with Dunn's post hoc tests. Results: Amputees with and without diabetes showed significantly narrower hip (p=0.01) and knee (p=0.08) joint space bilaterally compared to diabetic and healthy controls. This result suggests amputees could be at a higher risk of developing lower-limb osteoarthritis compared to diabetic and healthy individuals, which is in line with prior work demonstrating the prevalence of osteoarthritis in the amputee population. Conclusions: In agreement with our hypothesis, box plots showed trends of amputees with diabetes having the most narrowed joint space, followed by amputees without diabetes, then diabetic controls, and healthy controls. While not statistically significant, these trends suggest amputees with diabetes are at increased risk of developing osteoarthritis compared to amputees without diabetes. Perhaps the aggressive management of blood glucose and post-amputation physiotherapy treatments could help reduce joint deterioration in these patients. Future work will focus on increasing sample size to assess if these findings are generalizable to a larger population. Increased risks of osteoarthritis can lead to pain, limited mobility, and decreased quality of life. This study can potentially inform clinical standards of care for patients with amputations. Earlier interventions such as proactive musculoskeletal screenings and targeted exercises may reduce risks of developing osteoarthritis, leading to improved clinical outcomes.
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    Effects of Osteogenesis Imperfecta on the Cochlea and Sensorineural Hearing
    (2022) Huston, Lila Athena; Menegaz, Rachel A.; Handler, Emma; Organ, Jason; Gonzales, Lauren
    Background: Osteogenesis imperfecta (OI), a developmental disorder of type I collagen, is known to cause hearing loss in ~ 60% of the diseased population. Identified forms include conductive hearing loss (17.4% of OI patients), involving loss of function within the ossicular chain, and sensorineural hearing loss (25.8%), resulting from damage to the cochlea, with the most predominant form being mixed hearing loss (56.8%), involving damage to both the cochlea and ossicles. While OI-related pathologies have largely focused on the middle ear, the pathological appearance of the cochlea (the organ most often compromised in OI-related hearing loss) has gained little focus. In this study, we examine OI-related pathologies on the cochlea in a mouse model for the severe type III OI, to document 1) any visible variation between WT and OI variants, and 2) assess the encroachment of the otic capsule onto the cochlea by analyzing differences in duct volumes. We hypothesize that cochlea in mice with OI will have less consistent morphology overall than their WT counterparts due to abnormal growth of the bony capsule. Methods: 16 week old OIM mice (B6C3Fe a/a-Col1a2oim/J) (n=6) were compared to unaffected wildtype (WT) littermates (n=6) with no known hearing defects. High-resolution micro-CT scans were created for all specimens and 3D models and volumes of the cochlea were generated using 3D Slicer software. Two-tailed Mann-Whitney U-tests were used to investigate differences between 1) right and left ears of the same mouse to examine intraindividual symmetry and 2) differences in volumes between WT and OI cochlea. Results: No major morphologic differences between OI and WT were observed, except for minor areas of higher ossification at the base of the cochlea, mostly within the OI sample. Within WT specimens, we observed little intraindividual difference in the cochlear volume (0-3%). Within OI specimens, significant differences were observed in cochlear volume between right and left ears in the same animal (4-15%; p< 0.05), indicating potential unilateral effects. When average WT and OI volumes were compared, there was much overlap between the two samples although the OI volumes had a significantly larger range than the WT range (Mann-Whitney U, p< 0.05). Discussion: Overall, our results indicate that mice with OI are much more likely to have evidence of unilateral cochlear volume losses, despite very little difference in overall shape appearance, possibly due to bony capsule encroachment. This find indicates an extremely high potential for sensorineural and mixed hearing loss in OI-bred mice and elucidates at least one mechanism behind how this type of hearing loss might be occurring. Little is known about the pathological appearance of the cochlea in OI, leading to difficulty in managing hearing loss. Further investigation of the etiology and progression of cochlear pathologies will allow for better outcomes in hearing for those patients afflicted with OI-related hearing loss.
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    Unilateral Renal Hypoplasia
    (2022) Wieters, Matthew; Tran, Kylie; Smith, Zane; Thayyil, Hibaa; Weber, Landan; Fisher, Cara L.
    Background: Unilateral renal hypoplasia can occur as a result of, or in conjunction with, comorbidities such as hypertension, vascular diseases, pyelonephritis, and congenital developmental disorders. Contralateral renal compensation with hypertrophy of the sister kidney is one of the common sequelae of unilateral renal hypoplasia in addition to chronic renal failure (CRF) due to dysfunctional filtration and impaired blood pressure regulation. The incidence of renal hypoplasia according to epidemiological studies is 1 in 400 births. This case report examines the potential causes of a hypoplastic kidney found in the retroperitoneum of an 80-year-old female cadaver. Case Information: Detailed dissection of the left retroperitoneal space of the subject revealed a morphologically hypoplastic kidney with dimensions of 40 mm in length, 21 mm in width, and 13.5 mm in thickness. Hemisection of the kidney revealed cortical thinning as well. Contralateral compensation by the right kidney led to hypertrophic dimensions of 112 mm in length, 64 mm wide, and 46 mm in thickness. Average kidney pole-to-pole length is around 102 mm for the left kidney and 99 mm for the right kidney in women aged 80-89 years. Blood supply to the hypoplastic kidney appeared normal initially, however, upon measurement, the left renal artery was found to be much narrower at 1.72 mm in width in comparison to a typical renal artery diameter of 5 mm. The left renal vein exiting the hypoplastic kidney measured 57 mm in length compared to an average left renal vein length of 60-100 mm. The ureter exiting the left hypoplastic kidney was 1 mm wide while the right ureter measured 3.75 mm in width. No clear pathological characteristics were visualized in the kidney, such as cysts or tissue dysplasia. An additional finding of this case was an abdominal aortic aneurysm (AAA) measuring 140.5 mm from the inferior base at the common iliac artery bifurcation up to the superior border where the superior mesenteric artery branches. The AAA measured 40 mm wide and 27.75 mm in thickness. Conclusions: The compensatory enlarged right kidney and altered dimensions of the artery and vein associated with the hypoplastic kidney indicate potential for abnormal vasculature affecting overall kidney growth and function. The thin cortex also indicates reduced nephrotic function. Renal hypoplasia and impaired renal function predispose an individual to conditions such as hypertension or chronic renal failure. If patients present with a hypoplastic kidney, physicians can monitor potential chronic conditions and provide proper intervention. Likewise, physicians should be aware that patients with chronic cardiovascular and renal conditions are at a greater risk of developing an atrophic kidney if left untreated. Although a definitive etiology is unable to be determined due to a lack of sufficient past medical history, investigation into the relationships of anatomical variants adds to the current literature and understanding of this condition.
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    Musculoskeletal Differences Between Amputated and Non-Amputated Lower Limbs
    (2022) Finco, MG; Finnerty, Cait; Ngo, Wayne; Holley, Bethany; Menegaz, Rachel A.
    Purpose: People with lower limb amputations frequently experience greater risks of musculoskeletal injury. Forces active during walking help to develop and maintain the shape, volume, and strength of musculoskeletal tissues. Conversely, altered walking patterns following limb loss may lead to atrophy of muscle and bone tissues. Reductions in joint spaces are indicative of excess stress placed on the limb, which may lead to osteoarthritis. Bone loss in high stress regions like the femoral neck can reduce the bone's ability to resist compressive or rotational movements, making the bone more susceptible to fracture. The aim of this study was to measure musculoskeletal differences between an individual's residual (amputated) limb and intact (non-amputated) limb to identify structures vulnerable to injury. We hypothesized that the residual limb, compared to the intact limb, would show: 1) less muscle mass and more fat as indicators of muscle atrophy, 2) wider hip and knee joint spaces as indicators of osteoarthritis in the intact limb, and 3) decreased femoral neck width as an indicator of fracture risk. Methods: CT scans of 10 males (42-79 years) were obtained from the New Mexico Decedent Image Database. 3D Slicer software was used to measure gross skeletal properties, hip and knee joint dimensions, and cross-sectional muscle and fat tissue areas at the midshaft. A Wilcoxon Signed-Rank test was used to assess the differences between residual and intact limbs. The significance level was set at α ≤ 0.10 due to a small sample size. Results: Compared to the intact limb, the residual limb had significantly less muscle tissue area (p=0.010) and a significantly narrower femoral neck width (p=0.077). No significant differences were found in hip or knee joint spaces between limbs. Conclusions: In agreement with hypotheses 1 and 3, these results suggest residual limbs are at increased risk of muscle atrophy and femoral neck fracture compared to intact limbs. Loading inequalities between the residual and intact limb likely contribute to these results. A better understanding of the structural properties associated with musculoskeletal atrophy could inform targeted therapies to reduce the likelihood of injury in this population. Future studies will assess biomechanical properties, such as moment of inertia, to better understand the residual limb's ability to withstand torsional forces and fracture. Additional data on how musculoskeletal tissues respond to unloading at multiple structural levels can improve clinical interventions for lower limb strength and function in amputees.
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    Neurocranial Growth in the OIM Mouse Model of Osteogenesis Imperfecta
    (2022) Husain, Tooba S.; Miller, Courtney; Steele, Ashley T.; Gonzales, Lauren; Handler, Emma; Organ, Jason; Menegaz, Rachel A.
    Osteogenesis imperfecta (OI) is a disorder of type I collagen characterized by abnormal bone formation and weakened bone architecture. Human patients with OI have larger cranial vaults (macrocephaly), altered cranial base morphology including basilar invagination and platybasia (skull base flattening), and midfacial underdevelopment. The neurocranial changes may affect both underlying nervous tissue and growth patterns of the facial skeleton. However, we still do not fully understand how and when these divergent morphologies occur. The aims of this study are: (1) to investigate the integrated development of the skull and the brain in amouse model of OI; and (2) to identify the developmental trajectories of these structures to facilitate future therapeutic interventions. We hypothesize that compared to unaffected mice, mice with OI will have decreased brain volumes due to an overall reduction in cranial size and decreased cranial base angles (CBA) due to platybasia. To test these hypotheses, we used the osteogenesis imperfecta murine (OIM or B6C3FE a/a-Col1a2/J), a model for the severe type III OI in humans, and unaffected wild-type (WT) littermates. Mice were imaged using in vivo micro-computed tomography (micro-CT) at the juvenile (week 4; 10 OIM/14 WT) and adult (week 16; 9OIM/11 WT) stages. All measurements were taken in 3D Slicer software. 82 cranial landmarks were used to calculate centroid size, an estimate of overall head size. The segmentations tool was used to create virtual endocasts as a proxy for brain volume. The angle tool was used to measure CBA in the midsagittal plane using threelandmarks: foramen cecum, midsphenoidal synchondrosis, and basion. Mann-Whitney U tests were used to compare centroid sizes, brain volumes, and CBA between the genotypes. Both juvenile (p=0.008) and adult (p=0.003) OIM mice were found to have absolutely smaller brains than WT mice. However, OIM mice also have significantly smaller cranial centroid sizes compared to WT mice (p=0.003, p< 0.001). When scaled to cranial size, juvenile mice had relatively larger brain volumes (p=0.016) butadult OIM relative brain volumes were not significantly different from WT. No significant difference was seen in CBA at the juvenile (p=0.065) or adult (p=0.171) stages, however a trend was observed for decreased CBA at the adult stage. These results suggest that neurocranial dysmorphologies in OI may be more severe at earlier stages of postnatal development. Previous analyses of these mice have documented relative skeletal macrocephaly in both juvenile and adults, however here we document an increase in relative endocranial volume only at the juvenile stage. A reduction in CBA during growth, possibly due to platybasia, may underlie this decoupling between external and internal cranial morphology. Future work will investigate the effect of CBA on facial growth and midfacial underdevelopment in these mice. A better understanding of the integration and growth trajectory of the neurocranium is foundational for formulating treatments to manage basicranial instabilities in patients with OI. Support or Funding Information Funding was provided by an Indiana University Collaborative Research Grant, Ralph W. and Grace Showalter Trust, and a UNTHSC Physiology & Anatomy SEED Grant.
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    A Leak From Within: A Case Report on Flood Syndrome
    (2022) Srivastava, Kumaraman
    Flood syndrome is a very rare complication that can be found in patients with end-stage liver cirrhosis with concurrent ventral hernias. If the hernia ruptures, ascites can begin to leak uncontrollably from the opening which can become a nidus for infection if left untreated. This scenario is known as Flood syndrome, which was first described by Frank Flood in 1961. Flood syndrome is very difficult to manage for physicians as these patients are poor candidates for surgery but the ascitic leak will continue without surgical intervention. Currently, there is no standard of care for Flood syndrome. A 66-year-old Caucasian male with a past medical history of NASH cirrhosis, type 2 diabetes, COPD, umbilical hernia, and CAD presented with a sudden burst of ascitic fluid after his umbilical hernia spontaneously ruptured with no inciting event or trauma. The ascites had been progressively getting worse since the patient underwent his last therapeutic paracentesis (two weeks prior to admission) which drained 12.5 liters. Empiric antibiotics were started due to increased risk of bacterial peritonitis. IV albumin was also given to maintain oncotic pressure and prevent "third-spacing". Of note, patient was not given any additional fluids due to his hyponatremic state. General surgery and hepatology was consulted and recommended a binder with gauze changes as necessary since patient was a very poor candidate for surgery with a MELD score of 26. MELD scores are an excellent predictor of morbidity and mortality for patients with end-stage liver disease. After the patient was admitted, an attempt was made to control the ascitic leak via a pursestring suture. The patient's abdomen was prepped and draped in the standard sterile fashion. Lidocaine was used to anesthetize the skin of his umbilicus. There was about 2 cm diameter of gangrenous area with a hole leaking ascites in the middle. A pursestring suture of 3-0 chromic gut absorbable suture was placed around the defect to tightly close the wound. The patient tolerated the procedure well. There was no leak detected with the Valsalva maneuver after the placement of the pursestring. Two days later, however, the pursestring failed and the ascites began to leak again around the pursestring through the previously existing defect. Six days later, the patient was transferred to palliative care and later discharged despite the continued ascitic leak since he was not a transplant candidate or a candidate for surgery per surgery and hepatology. Patient was advised to continue weekly therapeutic paracenteses to manage the ascitic leak. The patient presented again twelve days later due to abdominal pain from a loop of small bowel being incarcerated and strangulated at the umbilical hernia. Despite being a poor surgical candidate, the patient and his wife agreed to undergo an umbilical hernia repair with mesh and small bowel resection due to the emergent nature of his case. The surgery was performed successfully and the patient was discharged from the hospital eleven days later in stable condition.
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    Massage application to increase the spread of local anesthesia in sciatic nerve blocks: A cadaver study
    (2022) Robertson, Taylor; Fisher, Cara L.; Handler, Emma; Nash, Daniel
    Introduction: Sciatic nerve blocks are essential for surgical treatment of various lower limb pathologies. Due to the complexity and variation of anatomical landmarks, ultrasound (US) guided injection of local anesthesia has become common practice. In patients with thicker thigh girth (i.e., obese patients) excess tissue may distort US penetration thereby diminishing efficacy of the nerve block and/or cause severe post-operative pain. Dye tracing techniques have been used to test the effectiveness of nerve blocks, but there is little research on using massage to manipulate anesthetic spread. Therefore, the aim of this study is to assess the effects of massage to manipulate local anesthesia spread in sciatic nerve blocks. We hypothesize massaging after injection will increase the spread of local anesthesia compared to non-massage post injection. Methods: Forty un-fixed cadaveric legs were injected with a mixture of methylene blue dye and 2% Lidocaine Hydrochloride. Specimens were divided into non-massage (control) (n=20) and massage (n=20) groups. Sciatic nerve blocks were performed by a nurse anesthetist using US guidance at the popliteal fossa traveling proximally until the sciatic nerve was identified and the location was tagged. Immediately following, massage group specimens received five repeated proximally directed massages with the US transducer head. Specimens from both groups were then dissected to expose the sciatic nerve. Measurements of the distance traveled from marked site of injection to proximal end of dyed area were measured and compared. Results: Spread of local anesthesia in the inferior-superior direction was significantly higher in the massage group than the control group (p≤0.05). Conclusions: Massaging post-injection caused a greater spread of local anesthesia during sciatic nerve block. Significance: Sciatic nerve block techniques often utilize nerve stimulation to identify the sciatic nerve location. This may be due to lack of US penetration through the gluteus maximus muscle. In patients with thicker thigh girth due to subcutaneous fat, imaging visibility may be more difficult as well. Our findings suggest that clinicians may block the sciatic nerve at a more distal location with US guidance and manipulate the anesthesia to the region of interest
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    Bilateral Seminal Vesicle Hypoplasia
    (2022) Cabrero, Daniel; Butson, Carter; Brown, Kerrie; Costello, Kathryn; Fisher, Cara L.
    Background: Seminal vesicles, two coiled sacs located posteriorly to the male bladder and lateral to the ampulla of the ductus deferens, play a vital role in male fertility. The duct of the seminal vesicle joins with the ampulla of the ductus deferens forming the ejaculatory duct, which then opens into the prostatic urethra. Producing about 70% of male semen, the seminal gland secretes alkaline fluid that contains fructose, prostaglandins, proseminogelin, and other substances that aid in successful fertilization. Contraction of the seminal vesicles releases seminal fluid into the ejaculatory duct where it mixes with spermatozoa from the ductus deferens. Little to no secretions from the seminal vesicles would likely result in male infertility due to the absence of fructose, the primary energy source for motile spermatozoa. Seminal vesicles can be affected by infection, cysts, tumors, hypoplasia, and congenital disease, but isolated seminal vesicle abnormalities are a very uncommon occurrence. There are a few disease states in which seminal vesicle abnormalities do occur. For example, Zinner syndrome is associated with renal agenesis and seminal vesicle hypoplasia or cysts. A Hoxa 13 gene mutation is associated with reduced seminal vesicle size and abnormal morphology, diminished dorsolateral ductal branching of the prostate, and agenesis of the bulbourethral gland. The complete bilateral absence of seminal vesicles can occur following a radical prostatectomy, where the prostate and seminal vesicles are excised together. Case Information: A pelvic dissection of an 82-year-old male donor during a first-year medical anatomy course revealed bilateral seminal vesicle hypoplasia. The seminal vesicle tissue was abnormally tough and embedded within enlarged prostatic tissue. The ductus deferens appeared normal and bilaterally intact. No other significant abnormalities in the reproductive tract nor the kidneys were noted. Conclusions: Based on our current research and ideas, seminal vesicle hypoplasia with no other concurrent reproductive abnormalities is unusual. Apart from the small seminal vesicles, our cadaver had a complete, bilateral set of male internal reproductive organs and an enlarged prostate with no signs of cancer treatment, ruling out the possibility of radical prostatectomy. Due to the presence of an intact urinary tract, Zinner syndrome is unlikely. The most promising possibility for this abnormality is a mutation of the Hoxa 13 gene based on the similarities between this mutation's presentation and our findings.
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    Effects of Osteogenesis Imperfecta on Dental Tissue Volumes in Mice
    (2022) Moore, Jacob; Handler, Emma; Menegaz, Rachel A.; Gonzales, Lauren; Organ, Jason
    Osteogenesis imperfecta (OI), commonly known as brittle bone disease, is associated with lifelong dental problems, including increased dental fractures, discolored teeth, and malocclusion. OI is a disorder of the type I collagen protein. Insufficient amounts or misshapen forms of this protein lead to disruptions in the microstructure of bone and teeth tissues. Dentin, the hard tissue which comprises the bulk of the tooth and absorbs shock forces during chewing, develops on a type I collagen matrix. Thus, collagen abnormalities in OI lead to disorganized and less stable dentin. Further, teeth in people with OI frequently exhibit dentin hypertrophy, where increased amounts of dentin are deposited at the interior of the tooth, shortly after dental eruption. Enamel, unlike dentin, develops on a matrix of non-collagenous proteins, and is thought to develop normally in OI. However, abnormalities in the underlying dentin in OI can lead to enamel fractures. Finally, the teeth in people with OI have often been noted to be smaller than those of people without OI. Because dental development occurs early in life, there is a lack of data surrounding the developmental processes and associated issues in dental development of children with OI. Mice are commonly used models for dental development, yet, this process has not yet been studied in mice. The objective of this study is to compare dental tissue volumes of teeth from mice with OI (oim) and wild type mice (wt) at different developmental stages to determine the degree of volume and gross dental size differences during late growth stages. Three-dimensional models of upper and lower first molars and incisors were created from microCT scans from oim and wt mice. Scans were taken at weaning age (four weeks after birth; "W4") and young adulthood (sixteen weeks after birth; "W16"). Dental tissue volumes were measured using 3D Slicer and normalized to mandibular centroid size. Mann-Whitney U tests were used to compare tissue volumes between genotypes and age groups. At W4 and W16, oim mice had significantly lower dentin volumes and total tooth volumes for upper incisors than wt mice (p < 0.05), with no significant difference between groups for other tooth types at either timepoint. At W16, total tooth volume was significantly lower in oim mice for molars before adjusting for mandible size (p < 0.05). For both oim and wt groups, W16 mice had significantly greater dentin, enamel, and total tissue volumes for lower and upper incisors compared to W4 mice (p < 0.05), as well as greater dentin volumes for lower molars (p < 0.05). These results demonstrate that the trend of smaller teeth in humans with OI also holds for the oim mouse. These differences are present at both the juvenile and young adult life stages. This affirms the oim mouse as a possible model for dental development in humans with OI. Further studies are needed to determine the developmental program of these volume differences at earlier growth stages.
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    The influence of humidity and precipitation on skeletal morphological variation in East Asia
    (2022) Cho, Elizabeth; Cowgill, Libby; Blomquist, Gregory
    Human ecogeographic proportions in Europe, Africa, and the Americas are well studied, but Asia remains underrepresented despite its diverse range of climates, latitudinal expanse, and long history of habitation. The monsoon is a significant environmental force across East Asia with two distinct phases: a summer phase and winter phase. The southwest winds of the summer component cross the equator bringing heavy rain during the warmer, humid months of the year while the winter's northeastern winds bring cold, dry air down from Siberia during the year's coldest months. Previous assessment of East Asian body form and minimum temperature during the monsoon's winter phase has found body size to conform with Bergmann's rule while limb length patterns did not follow Allen's rule. These analyses found that Southeast Asian are small overall, possibly due to the greater selective pressure of living in a humid climate which is exacerbated by the monsoon's heavy rain summer component. Reduction of body size in these populations could allow for better thermoregulation as the climate conditions of Southeast Asia are not conducive to heat dissipation via sweat evaporation. For this study, measurements throughout the body were gathered on female (N=439) and male (N=460) individuals from seven East Asian countries and represent 10 populations. Osteometric data and proportional indices were combined with appropriately matched autosomal SNP data, precipitation, and humidity data using linear mixed model analysis to evaluate the selective pressure of these climatic factors specifically associated with the summer phase of the monsoon. The influence of both climate variables was found to vary depending on the region of the body assessed. This further supports the need for ecogeographic research to assess the body as a whole and highlights the complexity of climatic adaptation.
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    Study of Cadaveric Posterior Circumflex Humeral Artery Variations
    (2022) Fajkus, Austin; Do, Tien; Cronk, Jacob; Fisher, Cara L.
    Purpose: There are concerns regarding the sequelae of blood clots post-vaccination due to suboptimal administration techniques with the ongoing incentive for vaccination against the Coronavirus Disease 2019 (COVID-19). Specifically, the risk of administering the intramuscular (IM) vaccine into an artery in the deltoid region. The posterior circumflex humeral artery (PCHA) is a small branch originating from the third part of the axillary artery, classically traveling with the axillary nerve, through the quadrangular space, to run along the inferior aspect of the deltoid muscle. This study investigates the presence and prevalence of variations of the PCHA not traversing in its classical path. Methods: Detailed dissection was performed on bilateral shoulders of 10 (n=20) human cadavers. The PCHA was identified in all 20 shoulders and their anatomic locations were assessed and categorized. Results: Of the 20 shoulders studied, 15% had anatomical variations of the posterior circumflex humeral artery traveling superiorly into the upper deltoid. Conclusions: Recent studies have highlighted the possibility of erroneous injection of the COVID-19 vaccine into the bloodstream as a risk of post-vaccination blood clots. The high prevalence of arterial variations revealed in this study provides an impetus for further research investigating the relationship between the variation in arterial anatomy and injection site "safe zones."
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    Unilateral Levator Scapulae Anatomical Variant in Female Cadaver
    (2022) Frangenberg, Alexander; Fisher, Cara L.
    Background The levator scapulae (LS) muscle is a superficial extrinsic muscle of the back, most commonly originating on the posterior aspect of the transverse processes of the first through fourth cervical vertebrae and inserting on the superior aspect of the medial border of the scapula. These attachment sites further indicate the action of the LS, which along with the trapezius and rhomboid muscles, function to elevate the scapula during overhead upper extremity movements and shrugging of the shoulders. This elevation of the scapula also causes the scapula to rotate clockwise, thus tilting the glenoid cavity inferiorly. If the scapula is fixed, the LS may also function to rotate the neck laterally at the cervical attachment points. The most common pathology of the LS is termed "levator scapulae syndrome" and is commonly due to poor posture, resulting in chronically achy, tight, and tender neck muscles that may impede movement and illicit excess pain. Case Information Dissection of the posterior cervical region and deep upper back on an embalmed 41-year-old female cadaver revealed a unilateral accessory muscle of the left LS muscle. This accessory slip inserted perpendicularly onto the broad aponeurotic fibers of the serratus posterior superior muscle, deep to the rhomboid major muscle. This anatomical variant is present in the literature and is a common site of accessory muscle attachment for the LS. Conclusions This case report describes the anatomical findings in-depth and discusses their prevalence in the literature. Interestingly, the literature indicates a higher predominance of unilateral LS accessory muscles in women compared to men, and this case report further supports this finding. Damage to the LS may be caused by high-velocity injuries, however, the most frequent presentation is implicated in cases of chronic neck pain due to poor posture. Due to the high rates of neck pain diagnosis in U.S. adults from an increasingly sedentary and technology-prevalent lifestyle, variations in muscular anatomy to the LS should not be overlooked. Such variations could play a role in the presence of chronic neck pain through the interaction with vascular and neurologic factors and should be considered during diagnosis and surgery of the region.
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    CT-based assessment of lower limb surface area, volume, and tissue composition: Implications for ecogeographic rules of thermoregulation
    (2022) Carey, Clay; Maddux, Scott D.
    Purpose: Anthropological research into human climatic adaptation has shown that global variation in skin surface-area to body volume (SA/V) ratio is generally consistent with theoretical predictions of ecogeographic rules. However, most studies have ignored the fact that internal body volume is comprised of various tissues (e.g., bone, muscle, fat) which exhibit different thermoregulatory properties. To address this issue, NSF has recently funded a research project in which human subjects will undergo full-body computed tomography (CT) scanning, and physiological testing during exposure to climatic extremes in an environmental chamber, to permit direct evaluation of associations between morphological variation and thermoregulatory physiology. Accordingly, the goal of the current project is to develop analytical methods for the NSF project, which will be used to 1) compare CT-derived SA/V ratios to traditional estimation methods, and 2) to evaluate potential volume differences in internal tissue compositions (e.g., bone, muscle, fat). Methods: 20 full body CT scans were selected from the New Mexico Decedent Image Database, a repository of CT scans made available to researchers by the New Mexico Office of the Medical Examiner. CT scan processing was performed in the Avizo software program. Appropriate anatomical landmarks were identified for segmentation of the hip, knee, and foot. The boundary between torso and lower limb is defined by a transverse plane between left and right greater trochanters. Separation of thigh and leg is defined by a similar plane between the medial and lateral midpoints of the knee on the tibial plateau. A final plane at the ankle passes through the medial and lateral malleoli. Identification of tissue types (bone, muscle, adipose) from the CT data began with generally accepted Hounsfield unit (i.e., density) ranges. These threshold ranges include +400 HU and higher for bone, -29 to +150 HU for muscle, and -190 to -30 HU for adipose. Results: Landmarks employed to orient planes of anatomical division were found to be readily identifiable across all specimens, permitting accurate collection of surface area and volume data for each of the 4 regions of interest (lower limb, thigh, leg, foot). In contrast, the use of basic Hounsfield unit threshold ranges was not found to permit reliable differentiation between bones, muscle, and adipose tissues. In particular, thresholding rages for bone had to be substantially altered to account for density-related differences between cortical bone, trabecular bones, and bone marrow. Hounsfield unit ranges for muscle and adipose did not need as much adjustment, but selections required more manual segmentation for contouring and removal of scanning artifacts. Conclusion: The methods developed by this project allow differences in tissue composition to be accurately accounted for during assessments of body volume. Thus, these methods provide advantages over traditional volumetric methods which assume tissue uniformity, and consequently, are well positioned to facilitate future experimental research into the relationships between anatomical variation and thermoregulatory physiology.
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    Bilaterally Absent Cephalic Veins: A Case Study
    (2022) Cronk, Jacob; Fajkus, Austin; Do, Tina; Fisher, Cara L.
    Background: The cephalic vein (CV) is one of the primary veins of the upper limb. It is a superficial vein located on the anterolateral surface of the arm and is a common site for venous access. The typical course begins along the radial aspect of the wrist and forearm where it joins with the median cubital vein (MCV) at the antecubital fossa and continues proximally through the superficial fascia, lateral to the biceps brachii muscle, and into the deltopectoral groove of the shoulder. It terminates by draining into the axillary vein in the deltopectoral triangle. The absence of the CV or variations in its location could have important implications for vascular procedures, such as Arteriovenous (AV) fistulas, which utilize the CV as the primary vein for preparing patients for long-term hemodialysis access. Case Information: An elderly Caucasian male cadaver presented with complete bilateral absence of the CV proximal to the antecubital fossa. Dissection revealed enlarged basilic veins (BV) and MCVs that crossed superficially to the bicipital aponeurosis and continued distally along the anterolateral side of the forearms towards the hands. Both limbs also showed a small anastomosis between the large MCV and the deep brachial vein (DBV) just distal to the bicipital aponeurosis. The BV on the right limb gives off one branch as the MCV that continues along the radial aspect of the forearm. Additionally, two smaller branches emerge and circumvent the medial epicondyle of the humerus and rejoin to form one vein that continues along the medial aspect of the forearm. The left limb showed an interesting anastomotic ring within the portion of the vein that would normally represent the MCV just distal to the bicipital aponeurosis. In contrast to the right limb, there was only one smaller branch from the BV that coursed around the medial epicondyle and travelled along the dorsal aspect of the forearm. The absence of the CV in the deltopectoral groove of both shoulders was also noted. Conclusions: This cadaveric case study illustrates a unique presentation of the upper limb venous architecture. With a significant portion of the U.S population requiring hemodialysis and/or developing end-stage renal disease, there has been an increase in the number of AV fistula procedures performed each year. Therefore, having a greater awareness of the variations of the CV may help to prevent complications in vascular procedures that require its use.
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    Massage application to decrease anesthetic spread in brachial plexus blocks: A cadaveric study
    (2022) Coffman, Taylor; Fisher, Cara L.; Handler, Emma; Nash, Daniel
    Introduction: Peripheral nerve blocks of the brachial plexus have become increasingly popular for upper limb surgery due to the benefits of using regional anesthesia. However, anesthetic from supraclavicular nerve blocks can spread medially and anesthetize the phrenic nerve, leading to partial paralysis of the diaphragm, also known as hemidiaphragmatic paresis. The addition of ultrasound guidance has reduced the incidence of phrenic nerve involvement due to the ability to see the spread of anesthetic in real time. There has been little research focused on whether or not ultrasound massage could manipulate anesthetic distally down the arm and away from the phrenic nerve. The aim of this study is to determine if ultrasound massage can be used to minimize the spread of anesthesia medially. Methods: Four fresh frozen cadavers were injected with 15 mls of a 25:75 mixture of methylene blue and 2% lidocaine. The specimens were divided into control (n=4) and massage (n=4) groups. A nurse anesthetist used ultrasound guidance to perform a supraclavicular block. Immediately following injection, the massage group received 5 distally directed massage strokes with the ultrasound transducer. After 15 minutes, both groups were dissected and measurements of anesthetic spread were taken. The medial spread was measured in all four cadavers and distal spread was measured in three out of the four. Results: Spread of anesthetic medially was not reduced in the massage group when compared to the control group. Distal spread of the anesthetic was increased in the massage group when compared to the control group (p< 0.05). Conclusions: The similarity of medial spread between the two groups implies ultrasound massage application will not prevent phrenic nerve palsy any more than a traditional supraclavicular block. The increased distal spread of the anesthetic suggests this technique can improve anesthesia to the brachial plexus by increasing the area the anesthetic travels. Significance: The incidence of phrenic nerve palsy during a supraclavicular block has decreased since the introduction of ultrasound, but some reservations persist when using the technique in non-healthy patients. Phrenic nerve palsy can cause respiratory distress in patients with pre-existing respiratory condition. Given the small sample size, continued study of this method is needed to further evaluate if this method could be used to reduce incidence of phrenic nerve palsy.
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    Postweaning Craniofacial Growth in the OIM Mouse Model of Osteogenesis Imperfecta
    (2022) Steele, Ashley T.; Mitchell, D. Rex; Organ, Jason; Menegaz, Rachel A.
    Osteogenesis imperfecta (OI) type III is a severe genetic disorder of type I collagen (Col1) resulting in bone fragility, reduced stature, and impaired craniofacial growth resulting in midface hypoplasia, dental malocclusions, and macrocephaly. While the adult OI murine (OIM) mouse model exhibits craniofacial phenotypes similar to patients with OI, little is known about the developmental trajectories of these phenotypes. To investigate the mechanisms by which Col1 mutations alter postnatal craniofacial growth, we analyzed the phenotype of the OIM mouse from the age of weaning until adulthood (skeletal maturity). OIM and wild-type (WT) littermates were scanned in-vivo with a Skyscan 1176 micro-CT system at 4 weeks (weaning) and 16 weeks (adulthood). 3D landmarks were collected using 3D Slicer software. Centroid size (a proxy for craniomandibular size) was compared using Mann-Whitney U tests. Morphological analysis for shape variation, including Generalized Procrustes analysis (GPA) and principal component analyses (PCA), were performed using the "geomorph" package in R. Procrustes ANOVAs were used to test for significant differences in craniomandibular shape between the genotypes. Morphological disparity was estimated as the Procrustes variance and statistically compared using the morphol.disparity function in R. Craniomandibular centroid sizes were significantly smaller in the OIM mice than the WT mice at both weeks 4 and 16 (p< 0.010). When the effects of size were accounted for by the GPA, significant shape differences were present (p< 0.002) throughout growth. For their size, both juvenile and adult OIM mice had shortened midfaces and increased cranial vault dimensions (relative macrocephaly) compared to WT littermates. Morphological differences were seen around the rostrum, temporal crests, and zygomatic arches. Marked vertical expansion of the neurocranium at the sagittal and coronal sutures presented with a concomitant basicranial shortening in the juvenile OIM mice only. Compared to WT, both juvenile and adult OIM mice had mandibles that were longitudinally shortened and mediolaterally wide. Morphological differences were seen around the incisal ramus and angular process at both ages, and in the coronoid process of adult OIM mice. Significantly different (p=0.001) morphological disparity between the genotypes existed only at the juvenile stage, demonstrating an overall decrease in variance throughout postnatal development period. This suggests that mice with greater variances in cranial shape experienced higher rates of attrition. This is potentially related to increased craniofacial fracture rates seen in the OIM mice. These results suggest that while the OIM craniofacial phenotype differs significantly from the WT throughout postweaning growth, functional constraints (such as feeding performance) may limit the degree of potential phenotypic divergence. Furthermore, while previous work in human patients with OI has linked the development of macrocephaly to basicranial shortening during early skull development, our results provide limited support for this hypothesis due to the absence of basicranial changes in adult OIM mice. Future investigations will examine perinatal and pre-weaning growth in the OIM mouse model to better understand the development of these craniofacial dysmorphologies, and to identify optimal growth windows during which interventions might recover bone quality and growth trajectories in patients with OI.
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    The Effects of Surgical Repair Devices in Middle Aged Adults (50-59 Years of Age) with Femoral Neck Fractures
    (2022) Roser, Thomas; Giga, Kashmeera; Collinge, Cory
    Purpose: Features of femoral neck fractures vary according to factors including age and mechanism of injury. In older patients (>60 years old), poor bone quality, the inability to limit weight bearing, along with co-morbidities where secondary surgeries may not be tolerated, often limits the utility of fracture repair in favor of replacement. Mechanism of femoral neck fractures in young adults in often higher energy, leading to atypical fracture angles and fracture comminution. Although this presents biomechanical challenges for implants after fracture repair, young adult patients (e.g. < 50 years old) are usually treated with repair as outcomes of arthroplasty in young patients are not well-defined. There remains a "middle-aged" group of 50-59-year-old patients in which femoral neck fracture mechanism and bone quality is highly variable. Decision for replacement versus repair becomes ill defined and more discretionary action is placed in the hands of the surgeon. Therefore, we asked if there are mechanical considerations in the fracture mechanism and surgical implants used that affect clinical outcomes. Potentially highly impactful decisions are made regarding the hardware and methodology used for augmentation, all of which could contribute to likelihood of success. Methods: This is a retrospective study of patients 50 to 59 years old with a femoral neck fracture treated with surgical repair between 2005 and 2017 at 26 Level 1 trauma centers in North America. A database including approximately 600 patients was evaluated for injury mechanism, internal fixation method implemented, and success of that intervention. Specific mechanical variables analyzed included fracture pattern: (vertical fracture angle, presence of fracture comminution) and stability of fracture repair: (quality of surgical realignment, use of established benchmarks for fracture repair including screw lengths, depths, numbers and placement). Results: Preliminary results following the recent conclusion of data collection indicated that of the 350 qualifying patients for analysis, higher success rates are suggested at 6 months postoperatively in regards to part placement as opposed to the internal fixation device chosen. Conclusion: As data analysis continues, this demonstrates a need for targeted evaluation and comparison of surgical reduction quality standards in femoral neck fracture repair while controlling for patient co-morbidities in hopes of identifying standard benchmarks of surgical placement. Future impact of this comprehensive database will allow for further investigation on this multifactorial topic.
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    (2022) Patterson, Tyler; Ramirez, Cynthia; Park, Chanyang; Sabbaghi, Tiffany; Patel, Kavita; Fisher, Cara L.
    Background: The spleen is the largest secondary lymphoid organ in the human body. It is an intraperitoneal organ, located in the left upper quadrant, posterior to the stomach and inferior to the diaphragm from the T8-T11 vertebral levels. The typical size of the spleen is 6 cm in width and 10 cm in length, with a depth length of 3 cm. Embryonically, it is derived from mesenchyme in the dorsal mesogastrium, and during fetal development in utero, the spleen transiently functions in the production of blood cells during fetal development. During adulthood, the spleen acts as a major repository for phagocytic cells, lymphocytes, and platelets, with a primary function of blood filtration. Hyposplenia is reduced size and function of the spleen. It is a condition that can complicate many diseases, such as sickle cell anemia, alcoholic liver disease, and many autoimmune disorders. Functional hyposplenia is characterized mostly by defective immune responses against pathogens. This cadaver case report presents the clinical condition of hyposplenia. Case Information: First-year medical students engage in anatomy courses in which routine cadaver dissections are performed. An abnormally small spleen was found in the upper abdominal cavity of a 66-year-old female. The donor presenting with the hyposplenia outlined in this case report passed from acute liver failure of uncertain etiology, chronic kidney disease, and peripheral artery disease. A typical spleen as compared to the cadaver's spleen indicated the cadaver's spleen was drastically reduced in size. The donor's spleen measured 2.72 cm in width and 4.38 cm in length, with a depth of 1.39 cm. Conclusions: In contrast to splenomegaly, the clinical determinant of a small spleen, hyposplenia, is unclear. However, there are potential causes for the spleen's size to decrease. Exposure to radiation, sickle cell disease, diabetes and chronic alcoholism are all hypotheses for this change in size. Patients with a defect in Kupffer cell function in relation to alcoholism have a predisposition to hyposplenism. In this case, the donor had the pathologies of diabetes and liver disease. The cause of death of acute liver failure of uncertain etiology could have been linked to the consumption of alcoholic beverages and their effects on the liver, as well as the effect on the Kupffer cells in the spleen.
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    Microstructure & Macrostructure Interrelationship in the Growing Hard Palate
    (2022) Miller, Courtney; Steele, Ashley T.; Organ, Jason; Menegaz, Rachel A.
    Bone strength is the result of microstructure (bone material properties) and macrostructure (bone size and shape), and deficiencies in either can produce skeletal fragilities with an increased likelihood of injury. The micro- and macro-architecture work together during re/modeling, ensuring that the skeleton is resistant to repetitive loading and preventing fracture. Bone is particularly responsive to loading during the rapid growth occurring in early life. Within the craniofacial complex, the hard palate is a unique structure that undergoes continuous loading due to continuous resting/active tongue pressure and bite forces. Because of this, palatal growth is theorized to drive midfacial growth. The aim of this study is to investigate longitudinal changes in the palate when the relationship between microstructure and macrostructure is perturbed. Here we use the OIM mouse (B6C3FE a/a-Col1a2OIM/J), a strain with a mutation to the structural protein type I collagen, resulting in increased bone fragility and improper biomineralization. We hypothesize that OIM and unaffected wild-type (WT) mice will be most similar in bone micro- and macro-structure in regions of the palate that experience high loading and therefore high rates of bone modeling/remodeling. Mice were micro-CT scanned at two timepoints: week 4 (juvenile) and week 16 (adult). BMD was collected at 3 regions (anterior, mid, and posterior palate). Mann-Whitney U tests were used to compare BMD between genotypes. 28 fixed and 10 sliding landmarks were placed across the palate. Geometric morphologic analyses were conducted to determine variation between genotypes in overall shape and curvature throughout growth. Average BMD decreased along an anteroposterior gradient for all mice. While juvenile OIM mice had lower palate BMD than WT mice at all regions, adult OIM mice had significantly lower BMD at only the anterior and posterior regions but not the midpalate. Procrustes ANOVA revealed significant differences in palatal shape between the genotypes at both the juvenile (p=0.001) and adult (p=0.0015) stages. Principal component analyses revealed that juvenile OIM mice had a shorter anterior palate and broader palate compared to WT mice, while adult OIM mice had a shorter posterior palate than WT mice. OI mice had flatter palatal arches in the coronal plane as juveniles, and in the midsagittal plane as juveniles and adults. Results show significant differences in palatal BMD and morphology between genotypes throughout growth, with fewer significant differences at the adult stage. Increased loading of the anterior palate during incisive gnawing may result in the convergence of bone macrostructure among adult mice, while increased strain at the midpalatal suture may necessitate increased BMD even in the presence of a biomineralization defect. Further research is needed to understand the functional significance of the anteroposterior palatal gradient and its relation to soft tissue attachments, particularly given the difference in oral behaviors between juveniles and adults.