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I am an MD-PhD clinician-scientist with medical and scientific interest in the outcomes of orthopaedic trauma and fracture treatment and the molecular enhancement of bone formation and fracture healing. My investigative goals include the identification of interventions (biological, mechanical/surgical, decision-making) that improve patient care, to better understand them in the laboratory and to adapt them to the patient population that I treat. To those ends, I work with several interdisciplinary teams consisting of biologists, engineers, surgeons, veterinarians, clinical investigators to enhance our understanding and provision of orthopaedic care.
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>> Gene regulation in bone healing - Using my background in molecular biology and gene regulation, I have delved into the investigation of a number of pathways and processes in bone healing and regulation that are consistent and synergistic with my orthopaedic trauma practice. I utilize primarily mouse models of traumatic fracture healing (with my collaborator, Kurt Hankenson) and have studied pathways related to thrombospondins, Wnt and Notch; and I have been especially interested in the geriatric condition (both fractures and bone loss). Select publications:
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• Hebb JH, Ashley JW, McDaniel L, Lopas LA, Tobias J, Hankenson KD, Ahn J. Bone healing in an aged murine fracture model is characterized by sustained callus inflammation and decreased cell proliferation. J Orthop Res. Epub Jul 14, 2017.
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• Ashley JW, Ahn J, Hankenson KD. Notch signaling promotes osteoclast maturation and resorptive activity. J Cell Biochem. 2015 Nov;116(11):2598-609.
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• Lopas LA, Belkin NS, Mutyaba PL, Gray CF, Hankenson KD, Ahn J. Fractures in geriatric mice show decreased callus expansion and bone volume. Clin Orthop Relat Res. 2014 Nov;472(11):3523-32.
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• Mutyaba PL, Belkin NS, Lopas L, Gray CF, Dopkin D, Hankenson KD, Ahn J. Notch signaling in mesenchymal stem cells harvested from geriatric mice. J Orthop Trauma. 2014;28 Suppl 1:S20-3.
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• Dishowitz MI, Mutyaba PL, Takacs JD, Barr AM, Engiles JB, Ahn J, Hankenson KD. Systemic inhibition of canonical Notch signaling results in sustained callus inflammation and alters multiple phases of fracture healing. PLoS One. 2013 Jul 3;8(7):e68726.
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>> Improving paradigms of medical decision-making - My investigations have led me to become involved in the systematic analysis of orthopaedic outcomes data and the systematic dissemination of education and information regarding evidence-based medicine. My collaborator, Joseph Bernstein, and I have taken this a step further and asked how to take medical decision-making into the future by not only refining what we know but exploring new methods to create improved paradigms to come to better clinical conclusions. Select publications:
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• Bernstein J, LeBrun D, MacCourt D, Ahn J. Presumed consent: licenses and limits inferred from the case of geriatric hip fractures. BMC Med Ethics. 2017;18(1):17.
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• Bernstein J, Kupperman E, Kandel LA, Ahn J. Shared Decision Making, Fast and Slow: Implications for Informed Consent, Resource Utilization, and Patient Satisfaction in Orthopaedic Surgery. J Am Acad Orthop Surg. 2016;24:495-502.
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• Bernstein JR, Maliha G, Ahn J, Bernstein J. Levels of Influence: Habituation and the Prevalence of Declared Conflicts of Interest. J Bone Joint Surg Am. 2016 Nov 16;98(22):e99.
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• Bernstein J, Morshed S, Helfet DL, Bhandari M, Ahn J. Applying evidence-based medicine principles to hip fracture management. Front Surg. 2014 Oct 20;1:40.
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• Bernstein J, Long JS, Veillette C, Ahn J. Crowd intelligence for the classification of fractures and beyond. PLoS One. 2011;6(11):e27620.
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>> Medical education (especially, the clinician-scientist) - Advances in biomedicine are driven by clinically minded scientists and scientifically minded clinicians. I have been studying, refining, improving, advocating for greater data-driven education and resource allocation for the training of medical scientists and clinician-scientists from the stages of undergraduate medical education and throughout graduate training. Select publications:
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• Winterton M, Ahn J, Bernstein J. The prevalence and cost of medical student visiting rotations. BMC Med Educ. 2016 Nov 14;16(1):291.
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• Schenker ML, Baldwin KD, Israelite CL, Levin LS, Mehta S, Ahn J. Selecting the Best and Brightest: A Structured Approach to Orthopedic Resident Selection. J Surg Educ. 2016 May 23.
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• Daye D, Patel CB, Ahn J, Nguyen FT. Challenges and opportunities for reinvigorating the physician-scientist pipeline. J Clin Invest. 2015 Mar 2;125(3):883-7.
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• Atesok KI, Hurwitz SR, Egol KA, Ahn J, Owens BD, Crosby LA, Pellegrini VD Jr. Perspective: Integrating research into surgical residency education: lessons learned from orthopaedic surgery. Acad Med. 2012 May;87(5):592-7.
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• Baldwin K, Namdari S, Bowers A, Keenan MA, Levin LS, Ahn J. Factors affecting interest in orthopedics among female medical students: a prospective analysis. Orthopedics. 2011 Dec 6;34(12):e919-32.
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>> The Practice of orthopaedic surgery. Select publications:
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• Baron MD, DeFrancesco CJ, Liu TC, Leone FT, Ahn J. A Teachable Moment After Orthopaedic Fracture in the Smoking Patient: A Randomized, Controlled Trial. J Orthop Trauma. 2017;31(8):e252-e254.
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• Bernstein J, Roberts FO, Wiesel BB, Ahn J. Preoperative Testing for Hip Fracture Patients Delays Surgery, Prolongs Hospital Stays, and Rarely Dictates Care. J Orthop Trauma. 2016 Feb;30(2):78-80.
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• Sagi HC / Ahn J, Ciesla D, Collinge C, Molina C, Obremskey WT, Guillamondegui O, Tornetta P 3rd; Orthopaedic Trauma Association Evidence Based Quality Value and Safety Committee. Venous Thromboembolism Prophylaxis in Orthopaedic Trauma Patients: A Survey of OTA Member Practice Patterns and OTA Expert Panel Recommendations. J Orthop Trauma. 2015 Oct;29(10):e355-62.
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• Scolaro JA, Schenker ML, Yannascoli S, Baldwin K, Mehta S, Ahn J. Cigarette smoking increases complications following fracture: a systematic review. J Bone Joint Surg Am. 2014 Apr 16;96(8):674-81.
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• Schenker ML, Yannascoli S, Baldwin KD, Ahn J, Mehta S. Does timing to operative debridement affect infectious complications in open long-bone fractures? A systematic review. J Bone Joint Surg Am. 2012 Jun 20;94(12):1057-64.
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I welcome discussion especially from students and trainees.
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Jaimo Ahn, MD, PhD, FACS
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Advisory Dean | Admissions & MSTP Steering Committees
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Medical Student & Assoc. Residency Director, Orthopaedic Surgery
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Co-Director, Orthopaedic Trauma & Fracture Reconstruction
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Perelman School of Medicine, University of Pennsylvania
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Selected Publications
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Jacobson AR, Whitney DG, Mamdouhi T, Janney CA, Blaszczak J, Ahn J.: Five-Year Fracture Rate for Transgender and Gender Diverse Patients on Gender-Affirming Hormone Therapy. J Am Acad Orthop Surg 33: e1133-e1141, Oct 2025.
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Patrick MD, Ahn J, Hankenson KD, Annamalai RT.: MALADAPTIVE IMMUNE-FIBROTIC AXIS DRIVES IMPAIRED LONG BONE REGENERATION UNDER MECHANICAL INSTABILITY. bioRxiv May 2025.
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Zondervan RL, Capobianco CA, Jenkins DC, Reicha JD, Fredrick L, Lam C, Schmanski JT, Isenberg JS, Ahn J, Marcucio RS, Hankenson KD.: CD47 is required for mesenchymal progenitor proliferation and fracture repair. Bone Res 13: 29, Mar 2025.
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Coscia A, Kumar A, Jandzinski M, Swany L, Fuster F, Ahn J.: Right heart dysfunction does not increase mortality associated with cemented hemiarthroplasty for hip fractures: A retrospective, preliminary analysis. PLoS One 20: e0318993, Feb 2025.
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Spitler C, Rutz R, Blackwood N, Wally M, Johnson J, Krause P, Ahn J, Mohammed Z, McClure M, Billings R, Yu Z, Yeager M; Orthopaedic Trauma Association's Evidence-Based Quality Value and Safety Committee.: Management of hip fracture patients on direct oral anticoagulants: a survey of orthopaedic trauma surgeons, systematic review, and meta-analysis. OTA Int 8: e360, Jan 2025.
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Coscia A, Jandzinski M, Talusan P, Ahn J.: Weightbearing in Select Geriatric Ankle Fractures Following Open Reduction Internal Fixation: Short Scientific Report. Foot Ankle Orthop 10: 24730114241310413, Jan 2025.
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Bernstein J, Lee A, Ahn J.: When does annual geriatric hip fracture mortality revert to baseline? Front Surg 11: 1359648, Oct 2024.
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Coscia A, Schweppe E, Anari J, Kneeland B, Horan A, Mehta S, Ahn J.: Diagnostic performance of digital tomosynthesis for postoperative assessment of acetabular fractures and pelvic ring injuries. Front Surg 11: 1461144, Oct 2024.
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Collinge CA, Giga K, Roser T, Lebus GF, Beltran MJ, Crist B, Sems SA, Gardner MJ, Sagi HC, Archdeacon MT, Mir HR, Rodriguez-Buitrago A, Mitchell P, Tornetta P 3rd; Young Femoral Neck Fracture Working Group.: Treatment Failure After Repair of Displaced Femoral Neck Fractures in Patients Compared by "Decade of Life": An Analysis of 565 Cases in Adults Less Than 60 years of Age. J Orthop Trauma 38: 418-425, Aug 2024.
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Rechter GR, Collinge CA, Rechter AJ, Gardner MJ, Sagi HC, Archdeacon MT, Mir HR, Rodriguez-Buitrago A, Mitchell P, Beltran MT; Young Femoral Neck Fracture Working Group.: Femoral Neck Fractures With Associated Ipsilateral Femoral Shaft Fractures in Young Adults <50 Years Old: A Multicenter Comparison of 80 Cases Versus Isolated Femoral Neck Fractures. J Orthop Trauma 38: 410-417, Aug 2024.
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Last updated: 12/02/2025
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The Trustees of the University of Pennsylvania
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