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Loukas, Marios

https://orcid.org/0000-0003-2811-6657

Mayo Clinic

Mayo Clinic

Citations 29

Impact of Structural Anomalies and Anatomical Variations on Operative Time in Abdominal Surgery—Systematic Review
Alleyne, Chrisanne , Montalbano, Michael J. , Raeburn, Kazzara, Chamberlain, Ronald, Grant, Robert, Loukas, Marios , Montalbano, Michael J , Raeburn, Kazzara

Clinical Anatomy | August 7, 2026 | Volume: No volume available | Issue: No issue available | Pages: No page available

10.1002/ca.70148 Get It

ABSTRACT Prolonged operative time is associated with increased surgical complications, resource utilization, and cost. While factors such as surgeon experience and patient habitus are well recognized, the impact of anatomical anomalies and variations remains poorly quantified. This systematic review evaluates the influence of abdominal structural anomalies and anatomical variations on operative time. Following PRISMA 2020 guidelines, a search of PubMed (2000–2025) identified 82 eligible studies. Operative‐time impact was assessed using added operative time relative to reference benchmarks. The unit of analysis was the procedure‐level observation. Observations were stratified by procedure category and surgical complexity and summarized using median added operative time and range. Among procedure‐level observations with available benchmarks, 13 of 14 (92.9%) structural anomalies, 48 of 54 (88.9%) situs inversus cases, and 10 of 11 (90.9%) other anatomical variants demonstrated increased operative time relative to baseline. Structural anomalies were associated with larger median increases, particularly in colorectal procedures, whereas anatomical variations demonstrated a more heterogeneous effect across procedural systems. Higher‐complexity procedures, including pancreatic operations, showed greater absolute increases in operative time. Preoperative identification of anatomical differences was associated with attenuation of operative delays. Structural anomalies are frequently associated with increased operative duration, whereas anatomical variations demonstrate a more variable and context‐dependent effect. The magnitude of operative time impact is influenced by procedural complexity and preoperative planning. Incorporating anatomical variability into surgical planning may reduce avoidable operative delays and improve operative efficiency.
Aortic and Pulmonary Valve Fenestrations: An Acquired Anatomic Entity During Adult Life
Loukas, Marios , Gowrie, Shelleen, Dai, Yuqian , Nahabedian, David, Davis, Nelson , Richards, Damion, Mitchell, Tyan, Gielecki, Jerzy, Gielecki, Jerzy

Clinical Anatomy | July 30, 2026 | Volume: No volume available | Issue: No issue available | Pages: No page available

10.1002/ca.70178 Get It

ABSTRACT This study aims to identify and characterize fenestrations in the aortic and pulmonary valves using an endoscopic approach and compare their prevalence and morphology in adult and fetal hearts. The research explores whether these fenestrations are congenital or acquired and their potential clinical implications. We analyzed 41 adult human hearts (mean age: 74.25 years; range: 62–92) and 97 fetal human hearts (mean gestational age: 26 weeks; range: 12–40). Specimens were preserved in alcohol‐phenol‐formaldehyde and examined using a Stryker 5 mm 0 degree endoscope to visualize valve structures in situ, followed by post‐endoscopic dissection. Two independent investigators assessed the specimens for fenestration prevalence, distribution, and morphology, categorized into ovoid, filamentous, and fenestrated types. Fenestrations were absent in all fetal hearts. Fenestrations were identified in 75.61% of adult hearts (31/41), with 74 fenestrations observed in total. Of these, 41 were in the pulmonary valve and 33 in the aortic valve. Ovoid fenestrations predominated in both valves (aortic: 76.3%, pulmonary: 85%), with significant distribution along leaflet edges, particularly in the left coronary and semilunar leaflets. No correlation with age or sex was found. The findings from this study suggest that valve fenestrations are more likely to be acquired postnatally, rather than representing congenital anomalies. The complete absence of fenestrations in all fetal heart specimens, contrasted with their high prevalence in adult hearts, supports this hypothesis. While our results do not directly prove a causal relationship, they align with prior literature proposing that biomechanical factors, such as cumulative leaflet stress, turbulent flow, and repeated coaptation, may contribute to the formation of fenestrations over time. These insights into the prevalence, morphology and leaflet distribution of fenestrations provide a valuable foundation for future research investigating their etiology, clinical significance, and potential role in valve dysfunction.
Extreme Heterogeneity Reported in Published Anatomical Meta‐Analyses: A Meta‐Epidemiological Study
IWANAGA, Joe, Walocha, Jerzy, Ottone, Nicolás Ernesto , Loukas, Marios , Tubbs, R. Shane, Ottone, Nicolás E , Iwanaga, Joe , Walocha, Jerzy Andrzej

Clinical Anatomy | July 8, 2026 | Volume: No volume available | Issue: No issue available | Pages: No page available

10.1002/ca.70180 Get It

ABSTRACT Following the introduction of meta‐analytic methodology into anatomical research, anatomical meta‐analyses have increased substantially. However, extremely high statistical heterogeneity is frequently observed in these studies, while its implications remain insufficiently discussed within anatomical research. The present study investigated the current state and patterns of heterogeneity in anatomical meta‐analyses and explored the interpretive implications of heterogeneity in anatomical evidence synthesis. A PubMed search was performed on May 21, 2026, using the title‐based search strategy: ((meta‐analysis[Title]) OR (meta analysis[Title])) AND (anatomy[Title]). Anatomical meta‐analyses focused on human structural anatomy were included. Reported I 2 values were extracted and descriptively analyzed by overall distribution and anatomical category. A total of 132 studies were identified, of which 61 anatomical meta‐analyses with analyzable heterogeneity data were included. The mean reported I 2 value was 95.27% (range 41%–100%), with a median I 2 of 98.77%. Most studies demonstrated extreme heterogeneity, with 86.9% reporting I 2 values exceeding 90%. Category‐specific analysis demonstrated consistently elevated heterogeneity across anatomical systems, including skeletal structures (mean I 2 = 99%), peripheral nerves (mean I 2 = 95%), and vascular anatomy studies (mean I 2 = 94.56%). Despite this, pooled prevalence estimates were frequently reported with highly precise numerical values and narrow confidence intervals. Extreme statistical heterogeneity is highly prevalent across anatomical meta‐analyses and appears to represent a widespread characteristic of anatomical synthesis research rather than an isolated statistical phenomenon. Although such heterogeneity likely reflects genuine biological and methodological variability, pooled anatomical estimates should be interpreted with caution, particularly when highly precise numerical estimates are reported despite substantial interstudy inconsistency. These findings highlight the importance of transparent heterogeneity reporting and anatomically stratified approaches in future anatomical meta‐analyses.
The Evolving Role of Clinical Anatomy: From Definition to Contribution
IWANAGA, Joe, Spinner, Robert J. , Bubb, Kathleen , D’Antoni, Anthony V. , Tabira, Yoko , Loukas, Marios , Tubbs, R. Shane, Khalil, Mohammed K , Loukas, Marios , Tabira, Yoko , Iwanaga, Joe , Khalil, Mohammed K.

Clinical Anatomy | June 12, 2026 | Volume: No volume available | Issue: No issue available | Pages: No page available

10.1002/ca.70166 Get It

ABSTRACT The term “clinical anatomy” is widely used in education and research, yet its conceptual boundaries continue to be interpreted in various ways. Prior consensus‐based efforts have emphasized integration, collaboration, and clinical relevance as central features of the field and have provided an important foundation for interdisciplinary engagement. At the same time, ongoing changes in academic structure, medical education, and interdisciplinary biomedical science raise important questions regarding how clinical anatomy can sustain its scientific identity and long‐term relevance. Building upon prior discussions, this article argues that the continued maturation of clinical anatomy depends on the integration of conceptual frameworks with the sustained production of rigorous, reproducible, and clinically meaningful scholarly contributions. Historical and contemporary examples alike demonstrate that the influence of clinical anatomy has been shaped through contributions that directly advanced clinical science and practice. Accordingly, continued emphasis on methodological rigor, reproducibility, clinically meaningful contribution, and educational accountability may be essential to the field's future development and relevance.
Relationship Between the Azygos Vein and the Greater Splanchnic Nerve: Application to Nerve Ablation Procedures for Improving Cardiac Function
Forrester, Deon , Davis, Nelson , Richards, Damion, Mitchell, Tyan, Tubbs, Shane, Loukas, Marios , Tubbs, Shane

Clinical Anatomy | June 6, 2026 | Volume: No volume available | Issue: No issue available | Pages: No page available

10.1002/ca.70161 Get It

ABSTRACT Although ablation of the greater splanchnic nerve is now being used to treat some patients with heart failure, the anatomical relationships between this nerve and the adjacent posterior intercostal veins used for the procedure are not well elucidated. Therefore, the present anatomical study was performed. The anatomy and relationships of the right GSN and the azygos vein were investigated in 50 adult anatomical donors. In the supine position, the anterior wall of the thorax was removed, and the relationship between the azygos vein and its tributaries and the overlying GSN was observed and documented with quantitation of the distances between these structures. At the T7, T8, and T9 vertebral levels, the mean distance between the GSN and the azygos vein was 3.05, 2.35, and 1.62 cm, respectively. We found that the closest distance between the GSN and the azygos vein was at the T9 vertebral level, with a mean distance of 1.62 cm. Therefore, for the shortest distance between vein and GSN, this level should also be considered for ablation level. Such additional anatomical data can help improve patient outcomes and decrease the complication rates of this procedure.
Femoral Nerve Block: A Review of the Relevant Applied Anatomy, Anatomical Variations, and Procedural Considerations
Dai, Yuqian, MD, Montalbano, Michael J.,, Marshall, Ewarld, Loukas, Marios , Montalbano, Michael J. , Montalbano, Michael J , Dai, Yuqian , Marshall, Ewarld

Clinical Anatomy | June 5, 2026 | Volume: No volume available | Issue: No issue available | Pages: No page available

10.1002/ca.70152 Get It

ABSTRACT Femoral nerve block is an essential regional anesthetic technique for surgery and analgesia of the anterior thigh, hip, and knee. Its effectiveness depends on understanding the femoral nerve's origin, branching pattern, fascial relationships, and common anatomical variations. This review summarizes current anatomical, cadaveric, and imaging studies to clarify the course of the femoral nerve and highlight variations such as high divisions, accessory branches, and vascular overlap that may influence block success. Approaches including landmark, nerve stimulator, and ultrasound‐guided techniques are reviewed with emphasis on procedural anatomy. Ultrasound features of the femoral nerve and fascia iliaca are correlated with cadaveric findings to outline optimal needle placement and spread of injectate. Continuous catheter methods, anesthetic selection, and volume considerations are also described. Comparative evidence indicates that ultrasound guidance improves accuracy, reduces vascular puncture, and decreases local anesthetic requirements compared with blind or stimulator‐based approaches. Clinical applications across orthopedic surgery, trauma care, and multimodal perioperative pathways are discussed, along with potential complications such as nerve injury, hematoma, systemic toxicity, and quadriceps weakness. Specifically, detailed knowledge of the femoral nerve's course beneath the fascia iliaca, its shifting proximity to the femoral vessels, and its variable early branching is the key to accurate needle placement, dependable block success, and fewer procedure‐related complications.
The Applications of Photogrammetry in Medical Education: A Review
Alleyne, Chrisanne , Loukas, M., Loukas, Marios , Montalbano, Michael J. , Żurada, Anna , Gielecki, Jerzy , Loukas, Marios

Clinical Anatomy | December 26, 2025 | Volume: 39 | Issue: 5 | Pages: 618-635

10.1002/ca.70050 Get It

ABSTRACT Photogrammetry has emerged as a powerful tool in medical education, offering precise and cost‐effective 3D anatomical models that enhance spatial learning and accessibility. This systematic review synthesizes evidence from forty‐eight (48) peer‐reviewed studies (2000–2025) to evaluate photogrammetry's applications, technical workflows, and educational outcomes in anatomy and surgical training. Findings demonstrate its effectiveness across training levels, with high learner satisfaction (e.g., 96.4% preference over traditional methods) and sub‐millimeter accuracy in rendering complex structures like neuroanatomy and musculoskeletal systems. Photogrammetry's adaptability for remote learning and specimen preservation addresses critical gaps in resource‐limited settings. However, challenges persist, including the lack of tactile feedback and difficulties in visualizing deep anatomical relationships. Future directions should focus on integrating artificial intelligence (AI)‐assisted processing, hybrid digital–physical models, and immersive technologies like virtual reality (VR)/augmented reality (AR) to bridge these gaps. By balancing innovation with evidence‐based implementation, photogrammetry can further solidify its role as a transformative adjunct in modern medical curricula.
Learning Anatomy With Radiology: A Systematic Review
Alexander, Monique , Loukas, Marios , Alexander, Madison , Loukas, Marios , Montalbano, Michael J.

Clinical Anatomy | December 6, 2025 | Volume: 39 | Issue: 3 | Pages: 368-381

10.1002/ca.70048 Get It

ABSTRACT Radiology education is critical for medical students' anatomical competence and clinical readiness. However, it remains insufficiently integrated in medical curricula as residency program directors describe interns' basic image interpretation as unsatisfactory. This review aims to assess the efficacy of ultrasound, CT, MRI, and X‐ray in facilitating the learning of anatomy among medical students. Following PRISMA guidelines, 983 articles were screened, and 52 studies published between 2000 and 2025 met the inclusion criteria by comparing radiology‐integrated anatomy education with traditional methods such as cadaver and atlas use. Data extraction covered study design, radiology modalities, and effect sizes. Both integrated and traditional methods consisted of medical student cohorts assessed on objective knowledge and skills with recorded quantitative outcomes. Included studies showed knowledge gains on multiple choice assessments (pooled Cohen's d = 0.99, 95% CI: 0.34–1.65) but with high heterogeneity among studies ( I 2 = 99.5%). Controlled designs were used in 21% of studies. Other investigations (68% of studies) used attitudinal surveys that revealed strong student preference for radiology‐integrated learning. Of the modalities present, ultrasound was predominant (85% of studies), with other modalities (CT: 15%; MRI/X‐ray: < 5%) substantially underrepresented despite clinical relevance. Radiology integration was shown to enhance anatomy education and clinical preparedness. The incorporation of radiology, specifically ultrasound, into anatomical education leads to a significant and substantial improvement in student learning outcomes. Future investigations can standardize assessments, expand multimodal research, and address global curricular disparities.
A Meta‐Analysis and Simplified Nomenclature for Diagonal Coronary Artery and Ramus Intermedius Across Adult and Pediatric Hearts
Dai, Yuqian , Constantini, Sabrina, Montalbano, Michael J. , Loukas, Marios , Montalbano, Michael J , Constantini, Sabrina

Clinical Anatomy | November 1, 2025 | Volume: 39 | Issue: 3 | Pages: 305-324

10.1002/ca.70034 Get It

ABSTRACT Anatomical descriptions of left‐sided oblique coronary branches remain inconsistent, hindering imaging interpretation and surgical planning. To quantify the prevalence, branching patterns and morphometry of the ramus intermedius (RI) and diagonal branches, and propose a unified nomenclature. Following PRISMA guidelines, a PubMed search up to 12 June 2025 yielded 623 records. Forty‐six studies involving 25,602 hearts were included, and random‐effects meta‐analysis was applied to pool prevalence and continuous outcomes. Overall, an additional left‐main branch (RI) was present in 25.2% (95% CI: 8.7–54.5). Trifurcation dominated (22.7%), whereas quadrifurcation and pentafurcation occurred in 3.7% and 1.3% respectively. The pooled RI/diagonal diameter averaged 2.21 mm (95% CI 2.02–2.39), and mean branch length was 49.1 mm (95% CI 37.8–60.5). Methodological heterogeneity was high but consistent patterns emerged across cadaveric and imaging modalities. An oblique “diagonal artery”, whether arising from the left main (RI) or anterior interventricular artery, is present in roughly 25% of hearts, averages 2.2 mm in caliber and extends to 49 mm. Recognizing this vessel family and standardizing the term “diagonal arteries” will improve coronary imaging reporting and guide revascularization strategies.
What Is Clinical Anatomy?—A Consensus Statement From the American Association of Clinical Anatomists
Rajaram‐Gilkes, Mathangi, Chaiyamoon, Arada , Ezra, David , Raoof, Ameed , Rae, Guenevere , Mtui, Estomih P., Detton, Alan J., Anand, Mahindra , Raeburn, Kazzara , Kim, Hee‐Jin , Sekhar, Laligam N., Watanabe, Koichi , D’Antoni, Anthony V. , Loukas, Marios , Spinner, Robert J. , Tubbs, R. Shane, Iwanaga, Joe , Ezra, David , Rae, Guenevere , Kim, Hee-Jin , Watanabe, Koichi , Antoni, Anthony D' , Loukas, Marios , Spinner, Robert J , Adds, Philip , Iwanaga, Joe , Bubb, Kathleen , Rajaram-Gilkes, Mathangi, Noël, Geoffroy P. J. C. , Hur, Mi-Sun , Sekhar, Laligam N. , Tabira, Yoko , Khalil, Mohammed K. , Adds, Philip J.

Clinical Anatomy | October 21, 2025 | Volume: 39 | Issue: 1 | Pages: 72-76

10.1002/ca.70040 Get It

ABSTRACT At the 42nd Annual Meeting of the American Association of Clinical Anatomists (AACA) in Bellevue, Washington, June 2025, two inaugural events—the Clinical Anatomy Fireside Chat (CAFC) and the Clinical Anatomy Symposium: Head and Neck 2025 (CAS)—fostered rich dialogue on the evolving role and operational definition of clinical anatomy. Experts from various clinical and anatomical disciplines explored the meaning of clinical anatomy, highlighting the absence of a universal definition despite its frequent use in education and research. Through these interdisciplinary discussions, a consensus emerged: clinical anatomy is not defined solely by the possession of clinical credentials but by the integration of anatomical knowledge and clinical relevance, achieved most effectively through collaboration. Clinical anatomy education and research require different depths of clinical knowledge depending on the audience and objective, and meaningful collaboration can bridge gaps in expertise. The symposium further illustrated that high‐quality clinical anatomy emerges from mutual respect and reciprocal insight between clinicians and anatomists. This article presents a consensus statement developed by AACA representatives and invited speakers, affirming that collaboration is not only foundational to the practice of clinical anatomy but also fundamental to its definition. These conclusions aim to guide future educational models, research strategies, and interdisciplinary partnerships in the field of clinical anatomy.