Jaimo Ahn, MD, PhD

Harold W. and Helen L. Gehring Research Professor of Orthopaedic Surgery
Associate Chair for Education, Orthopaedic Surgery
Chief and Service Co-Director, Orthopaedic Trauma
Area of Practice
Orthopaedic Trauma

Dr. Ahn is a surgeon who specializes in caring for those who have sustained orthopaedic trauma and those in need of fracture related care.

He was born in Seoul, Korea and grew up in Chicago, Los Angeles and the San Francisco Bay Area. His higher educational tour began at Stanford University (where he became enthralled with medicine, science and education) followed by a research year at the University of California, San Francisco and a move across the country to Philadelphia to the University of Pennsylvania where he completed his MD, PhD (in Cell and Molecular Biology), Post-Doctoral Fellowship (Molecular Orthopaedics) and Residency (Orthopaedic Surgery).  He then rounded out his education with a Fellowship in orthopaedic traumatology at Hospital for Special Surgery / Cornell University, an AO Fellowship in orthopaedic trauma and hip surgery at Inselspital (University of Bern, Switzerland) and finally an AOA Travelling Fellowship through western Canada and US.  After almost 25 years at Penn, he joined Michigan Orthopaedics to help lead orthopaedic trauma as well as the education and professional development of trainees and fellow faculty.

When not caring for patients, he has helped lead his field and musculoskeletal health in the US and internationally through foundations such as the US Bone and Joint Initiative, Foundation for Orthopaedic Trauma and AO Foundation, academic publications such as NEJM, JAMA and Cochrane Collaborative and professional organization such as the Orthopaedic Trauma Association, Association of Bone and Joint Surgeons and American Physician Scientists Association, and governmental agencies such as the National Institutes of Health (NIH) and Congressionally Directed Medical Research Programs (DoD).  He is especially proud of his international service through Orthopaedics Overseas (Nicaragua), BUP (Botswana), Mada Foundation / Sign International (Madagascar) and his teaching-mentoring service to thousands of students, residents, fellows and young faculty all over the world.

If you have not already, please take a look at what we do in Orthopaedic Trauma and meet your Care Team.  Curious about your kind of fracture?  Here is a great place to learn and explore.

Clinical Interests

Dr Ahn’s mission is to provide the best skeletal trauma / fracture care possible—while being compassionate, experience & evidence based, patient & family oriented—to every one of his patients.  He has applied these principles to care for those injured locally, regionally and those from South America, Asia, Europe and Africa who have sought his care. His clinical expertise includes:

His U of M Health physician profile is here and clinical expertise includes the following (see some case examples):

  • Complex extremity & periarticular (around the joint) fractures
  • Pelvic & acetabular (hip socket) fractures
  • Nonunions (not healing), malunions (healed crooked) and osteomyelitis (bone infections)
  • Limb salvage (preventing amputations) and distraction osteogenesis (bone regeneration / lengthening)

Research Interests (for indexed publications, see here)

  • Trauma / fracture outcomes including clinical trials
    1. Fracture fixation in the operative management of hip fractures (FAITH).  Lancet, 389:1519-1527. 2017.
    2. Fractures in Elderly Americans Associated With Walking Leashed Dogs.  JAMA Surgery, 154:458-459. 2019
    3. Total Hip Arthroplasty or Hemiarthroplasty for Hip Fracture. NEJM, 381:2199-2208. 2019.
    4. Reconstruction of Traumatic Defects of the Tibia with Free Fibular Flap and External Fixation.  Annals of Plastic Surgery, 85:516-521. 2020. 
    5. Simple Surgical Mask Modification for Increased Respiratory Protection during SARS-CoV-2. Under review, 2021.
  • Surgical / medical decision-making 
    1. Crowd Intelligence for the Classification of Fractures and Beyond.  PLoS One, 6:e27620. 2011.
    2. Applying Evidence Based Medicine to Hip Fracture Management.  Frontiers in Surgery. 1:40.  2014. 
    3. Shared Decision Making, Fast and Slow.  JAAOS, 24:495-502. 2016.
    4. Defining the Key Parts of a Procedure. JAAOS, 26:142-147. 2018.
    5. Predicting Life Expectancy Following Geriatric Hip Fracture. PLoS One, 16:e0261279. 2021.
  • Surgical / biomedical education
    1. Factors affecting Interest in Orthopaedics Among Female Medical Students: A Prospective Analysis. Orthopaedics, 34:919-932.  2011.
    2. Reinvigorating the Physician-Scientist Pipeline. JCI, 125:883-887. 2015. 
    3. Leading From the Front: An Approach to Increasing Racial and Ethnic Diversity in Surgical Training Programs.Annals of Surgery, 269:1012-1015. 2019.    
    4. Motivations and impact of international rotations in low- and middle-income countries for orthopaedic surgery residents: Are we on the same page? American Journal of Surgery, 221(2):245-253. 2020.  
    5. Effect of Cognitive Task Simulation in Transfer of Performance Skills in an AO Practical Skills Lab). In press, JOT, 2021.
  • Literature synthesis / evidence-based medicine
    1. Venous Thromboembolism Prophylaxis in Orthopaedic Trauma Patients.  JOT, 29:e355-362. 2015.
    2. Acute Compartment Syndrome. JOT, 32:e181-e184. 2018.
    3. Randomized-Controlled Trials for Geriatric Hip Fracture are Rare and Underpowered. JBJS, 101:e132. 2019.
    4. Treatment of lower extremity fractures in chronic spinal cord injury: a systematic review of the literature. PM&R, e-pub June 5, 2020.
    5. The Rising Burden of Alcohol-Associated Fractures in the US: Three-Fold Increase Between 2000 and 2017. Under review, 2021.  
  • Molecular regulation of bone healing and re/generation
    1. R-spondin-2 is an osteoblast-produced Wnt agonist that regulates osteoblastogenesis.  Bone Research (Nature Press), 6:24. 2018.
    2. Periosteal mesenchymal progenitor dysfunction and extraskeletally-derived fibrosis contribute to atrophic fracture nonunion.  JBMR, 34:520-532. 2019.
    3. Bone marrow adipogenic lineage precursor (MALP) cells regulate osteoclastogenesis during bone remodeling and pathologic bone loss. JCI, November 18, 2020.
    4. Targeting cartilage EGFR pathway for osteoarthritis treatment. Science TM, January 13, 2021.
    5. The critical role of Hedgehog-responsive mesenchymal progenitors in meniscus development and injury repair. eLife, 10:e62917. 2021.  
  • MOTR Collaborative


  • Undergraduate Studies, Biologic Sciences, Stanford University, Stanford, CA
  • Medical & Graduate School, University of Pennsylvania, Philadelphia, PA
  • Residency, Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA
  • Fellowship, Orthopaedic Traumatology at Hospital for Special Surgery, New York, NY
  • Fellowship, Orthopaedic Trauma & Hip Surgery, Inselspital - University of Bern, Bern, Switzerland 
  • Certificate (currently enrolled), Orthopaedic Leadership (AOA APEX Program), USC Marshall School of Business