Meir Marmor, MD

Associate Professor
Orthopaedic Surgery
+1 628 206-8812

Dr. Meir T. Marmor has a strong clinical interest in treatment of complex fractures, fracture complications, and fractures in the elderly population as well as in joint replacement surgery. His clinical practice involves use of advanced imaging techniques, computer assisted and minimally invasive surgery. Dr. Marmor practice includes treatment of all long-bone and intra-articular fractures and their complications, such as infected fracture fixations and fracture non-unions. Dr. Marmor also performs primary joint replacements of hips, knees, shoulders and elbows as well as revision joint replacements for infected, dislocating or painful joint replacements.


"Dr. Marmor’s research interests include muscle compartment syndrome, tibia fracture complications, elderly/geriatric fractures, evidence based medicine, surgical education, precision medicine and decision support solutions for orthopaedic surgery procedures, and surgical outcomes.  Dr. Marmor’s research expertise includes clinical research, biomechanical research and computational science techniques such as big data analysis, artificial intelligence, computer modeling and simulation techniques.


Dr. Marmor has been an invited speaker at national and international conferences, speaking on topics such as measurement of outcomes in fracture surgery, evaluation and management complex fractures, fracture imaging and advanced techniques in fracture surgery. He teaches orthopaedic trauma surgery in regional, national and inter-national forums, and he is also the editor of a orthopaedic surgery textbook titled – Decision Making in Orthopaedic Trauma. Dr. Marmor is a devoted teacher and mentor to students and trainees of all levels at UCSF and beyond.


Dr. Marmor is a graduate with honors of the Israeli Institute of Technology medical school. After medical school he served in the Israeli army for 7 years as a medical officer and then for 5 years as a flight surgeon. While in the military he completed his orthopaedic residency in Tel-Aviv and Barzilai medical centers in Israel. He has also undergone training in trauma management at the Tel Hashomer medical center in Israel. After completing his residency, he had further clinical training in Orthopaedic Trauma Surgery as a clinical fellow at UCSF, and in joint replacement surgery as a clinical fellow in the Joint Replacement Institute in Los Angeles.

Dr. Marmor is a Fellow of the American Academy of Orthopaedic Surgeons, and active member of the Orthopaedic Trauma Association, Orthopaedic Research Society, California Orthopaedic Association, American Medical Association, Califonia Medical Association, Societe Internationale de Chirurgie Orthopedique et de Traumatologie (SICOT). Dr. Marmor is a proud husband and father to three children, and is committed to providing the highest quality of patient care, resident education and medical research."

Interests: Fracture healing, modeling and simulation, fracture biomechanics, minimal invasive fracture surgery, precision medicine, data sceince including analysis of "big data", computational science including modeling, simuation and artificial intelligence, musculoskeletal biomechanics

Publications: 

Fluoroscopic images of the sacroiliac joint alone are unable to identify simulated flexion or extension malreduction of the anterior pelvic ring in AO/OTA 61-B2.3 pelvic injuries.

European journal of orthopaedic surgery & traumatology : orthopedie traumatologie

Working ZM, El Naga AN, Hoogervorst P, Knox R, Marmor MT

Identification of subtle residual sacroiliac joint flexion and extension malreductions in AO/OTA 61-C1.2 (APC3) pelvic injuries after provisional anterior ring reduction.

European journal of orthopaedic surgery & traumatology : orthopedie traumatologie

El Naga AN, Working ZM, Hoogervorst P, Knox R, Marmor MT

Skin Antisepsis before Surgical Fixation of Extremity Fractures.

The New England journal of medicine

PREP-IT Investigators, Sprague S, Slobogean G, Wells JL, O'Hara NN, Thabane L, Mullins CD, Harris AD, Wood A, Viskontas D, Apostle KL, O'Toole RV, Joshi M, Johal H, Al-Asiri J, Hymes RA, Gaski GE, Pilson HT, Carroll EA, Babcock S, Halvorson JJ, Romeo NM, Matson CA, Higgins TF, Marchand LS, Bergin PF, Morellato J, Van Demark RE, Potter GD, Gitajn IL, Chang G, Phelps KD, Kempton LB, Karunakar M, Jaeblon T, Demyanovich HK, Domes CM, Kuhn GR, Reilly RM, Gage MJ, Weaver MJ, von Keudell AG, Heng M, McTague MF, Alnasser A, Mehta S, Donegan DJ, Natoli RM, Szatkowski J, Scott AN, Shannon SF, Jeray KJ, Tanner SL, Marmor MT, Matityahu A, Fowler JT, Pierrie SN, Beltran MJ, Thomson CG, Lin CA, Moon CN, Scolaro JA, Amirhekmat A, Leonard J, Pogorzelski D, Bzovsky S, Heels-Ansdell D, Szasz OP, Gallant JL, Della Rocca GJ, Zura RD, Hebden JN, Patterson JT, Lee C, O'Hara LM, Marvel D, Palmer JE, Friedrich J, D'Alleyrand JG, Rivera JC, Mossuto F, Schrank GM, Guyatt G, Devereaux PJ, Bhandari M, The PREP-IT Investigators

Wearable activity data can predict functional recovery after musculoskeletal injury: Feasibility of a machine learning approach.

Injury

Braun BJ, Histing T, Menger MM, Herath SC, Mueller-Franzes GA, Grimm B, Marmor MT, Truhn D, AO Smart Digital Solutions Task Force(Andrew M Hanflik, Peter H Richter, Sureshan Sivananthan, Seth

Inpatient pain alleviation after orthopaedic trauma surgery-are we doing a good job?

European journal of orthopaedic surgery & traumatology : orthopedie traumatologie

Marmor MT, Mahadevan V, Solans BP, Floren A, Jarlsberg L, Cohen I, Savic R

Physiologic Motion in the Intact and Unstable Syndesmosis During Plantigrade Weight Bearing in Controlled Ankle Motion Boots.

The Journal of foot and ankle surgery : official publication of the American College of Foot and Ankle Surgeons

Matz J, Debopadhaya S, Herfat S, Marmor MT

The Importance of Pragmatic Study Design to the Scholarly Influence of Surgical Hip Fracture Randomized Controlled Trials.

Journal of the American Academy of Orthopaedic Surgeons. Global research & reviews

Marmor M, Guenthner G, Getman T, Ghert M

"Bring Your Own Device"-A New Approach to Wearable Outcome Assessment in Trauma.

Medicina (Kaunas, Lithuania)

Braun BJ, Histing T, Menger MM, Platte J, Grimm B, Hanflik AM, Richter PH, Sivananthan S, Yarboro SR, Gueorguiev B, Pokhvashchev D, Marmor MT

Complex Orthopaedic Trauma Is Shifting Away From Level I to Non-Level I Trauma Centers: An Analysis of the National Trauma Data Bank.

Journal of the American Academy of Orthopaedic Surgeons. Global research & reviews

Marmor MT, Coufal S, Parel PM, Rezaei A, Morshed S

Usage of orthopaedic trauma registries among members of the International Orthopaedic Trauma Association: How are we doing?

OTA international : the open access journal of orthopaedic trauma

Nguyen MP, Paull TZ, Miclau T, Marmor MT

Wireless Measurements Using Electrical Impedance Spectroscopy to Monitor Fracture Healing.

Sensors (Basel, Switzerland)

Fukase N, Duke VR, Lin MC, Stake IK, Huard M, Huard J, Marmor MT, Maharbiz MM, Ehrhart NP, Bahney CS, Herfat ST

Comparison of the Neer classification to the 2018 update of the Orthopedic Trauma Association/AO fracture classification for classifying proximal humerus fractures.

OTA international : the open access journal of orthopaedic trauma

Marmor MT, Agel J, Dumpe J, Kellam JF, Marecek GS, Meinberg E, Nguyen MP, Sims S, Soles GL, Karam MD

Adaptation of the Centers for Disease Control Surgical Wound Classification System for Orthopaedic Trauma Surgery.

Journal of orthopaedic trauma

Scolaro JA, Agel J, Marmor M, Dumpe J, Karam M, Kellam J, Meinberg E, Munz J, Nguyen M, Soles G, Stinner D, Marecek GS

Use of Wearable Technology to Measure Activity in Orthopaedic Trauma Patients: A Systematic Review.

Indian journal of orthopaedics

Marmor MT, Grimm B, Hanflik AM, Richter PH, Sivananthan S, Yarboro SR, Braun BJ

Wearable technology in orthopedic trauma surgery - An AO trauma survey and review of current and future applications.

Injury

Braun BJ, Grimm B, Hanflik AM, Richter PH, Sivananthan S, Yarboro SR, Marmor MT

Correction to: Comparison of fibula strut and calcium phosphate cement augmentation of the medial buttress in 2-part proximal humerus fractures reconstruction: a biomechanical study.

European journal of orthopaedic surgery & traumatology : orthopedie traumatologie

Pokhvashchev D, Knox R, Herring M, Herfat S, Marmor MT

Association of COVID-19 With Achieving Time-to-Surgery Benchmarks in Patients With Musculoskeletal Trauma.

JAMA Health Forum

da Leah Gitajn, Paul M. Werth, Sheila Sprague, Nathan O’Hara, Gregory Della Rocca, Robert Zura, Meir Marmor, Christopher M. Domes, Lauren C. Hill, Christine Churchill, Christine Townsend, Chi Van, Natalie Hogan, Cara Girardi, Gerard P. Slobogean, Gerard P. Slobogean, Sheila Sprague, Jeffrey Wells, Mohit Bhandari, Jean-Claude D'Alleyrand, Anthony D. Harris, Daniel C. Mullins, Lehana Thabane, Amber Wood, Gregory J. Della Rocca, Joan Hebden, Kyle J. Jeray, Lucas Marchand, Lyndsay M. O'Hara, Robert Zura, Michael J. Gardner, Jenna Blasman, Jonah Davies, Stephen Liang, Monica Taljaard, PJ Devereaux, Gordon H. Guyatt, Diane Heels-Ansdell, Debra Marvel, Jana Palmer, Jeff Friedrich, Nathan N. O'Hara, Frances Grissom, I. Leah Gitajn, Saam Morshed, Robert V. O'Toole, Brad A. Petrisor, Megan Camara, Franca Mossuto, Manjari G. Joshi, Justin Fowler, Jessica Rivera, Max Talbot, Shannon Dodds, Alisha Garibaldi, Silvia Li, Uyen Nguyen, David Pogorzelski, Alejandra Rojas, Taryn Scott, Gina Del Fabbro, Olivia P. Szasz, Paula McKay, Andrea Howe, Joshua Rudnicki, Haley Demyanovich, Kelly Little, Adam Boissonneault, Michelle Medeiros, Genevieve Polk, Eric Kettering, Diamond Hale, Nirmen Mahal, Andrew Eglseder, Aaron Johnson, Christopher Langhammer, Christopher Lebrun, Theodore Manson, Jason Nascone, Ebrahim Paryavi, Raymond Pensy, Andrew Pollak, Marcus Sciadini, Yasmin Degano, Haley K. Demyanovich, Katherine Joseph, Heather Phipps, Eric Hempen, Herman Johal, Bill Ristevski, Dale Williams, Matthew Denkers, Krishan Rajaratnam, Jamal Al-Asiri, Jordan Leonard, Francesc A. Marcano-Fernández, Jodi Gallant, Federico Persico, Marko Gjorgjievski, Annie George, Sarah M. McGaugh, Kaitlyn Pusztai, Sarah Piekarski, Mavis Lyons, Julia Gennaccaro, Roman N. Natoli, Greg E. Gaski, Todd O. McKinley, Walter W. Virkus, Anthony T. Sorkin, Jan P. Szatkowski, Joseph R. Baele, Brian H. Mullis, Yohan Jang, Lauren C. Hill, Andrea Hudgins, Courteney L. Fentz, Maricela M. Diaz, Katelyn M. Garst, Emma W. Denari, Patrick Osborn, Sarah Pierrie, Eric Martinez, Joseph Kimmel, John D. Adams, Michael L. Beckish, Christopher C. Bray, Timothy R. Brown, Andrew W. Cross, Timothy Dew, Gregory K. Faucher, Richard W. Gurich, David E. Lazarus, S. John Millon, M. Jason Palmer, Scott E. Porter, Thomas M. Schaller, Michael S. Sridhar, John L. Sanders, L. Edwin Rudisill, Michael J. Garitty, Andrew S. Poole, Michael L. Sims, Robert M. Carlisle, Erin Adams-Hofer, Brandon S. Huggins, Michael D. Hunter, William A. Marshall, Shea Bielby Ray, Cory D. Smith, Kyle M. Altman, Julia C. Bedard, Markus F. Loeffler, Erin R. Pichiotino, Austin A. Cole, Ethan J. Maltz, Wesley Parker, T. Bennett Ramsey, Alex Burnikel, Michael Colello, Russel Stewart, Jeremy Wise, M. Christian Moody, Matthew Anderson, Joshua Eskew, Benjamin Judkins, James M. Miller, Stephanie L. Tanner, Rebecca G. Snider, Christine E. Townsend, Kayla H. Pham, Abigail Martin, Emily Robertson, John Wilson Skyes, Utku Kandemir, Meir Marmor, Amir Matityahu, R. Trigg McClellan, Eric Meinberg, Theodore Miclau, David Shearer, Paul Toogood, Anthony Ding, Erin Donohue, Jothi Murali, Ashraf El Naga, Jennifer Tangtiphaiboontana, Tigist Belaye, Eleni Berhaneselase, Alexandra Paul, Kartik Garg, Dimitry Pokhvashchev, Joshua L. Gary, Stephanie J. Warner, John W. Munz, Andrew M. Choo, Timothy S. Schor, Milton L. "Chip" Routt, Mayank Rao, Guillermo Pechero, Adam Miller, Michael Kutzler, Jennifer E. Hagen, Matthew Patrick, Richard Vlasak, Thomas Krupko, Kalia Sadasivan, Michael Talerico, Marybeth Horodyski, Chris Koenig, Daniel Bailey, Daniel Wentworth, Chi Van, Justin Schwartz, Marissa Pazik, Niloofar Dehghan, Clifford B. Jones, J. Tracy Watson, Michael McKee, Ammar Karim, Debra L. Sietsema, Alyse Williams, Tayler Dykes, William T. Obremsky, Amir A. Jahangir, Manish Sethi, Robert Boyce, Philip Mitchell, Daniel J. Stinner, Karen Trochez, Andres Rodriguez, Vamshi G...

Extracorporeal measurement of femoral nail length in the treatment of trochanteric hip fractures: the "box" technique.

OTA international : the open access journal of orthopaedic trauma

Garg K, Herring MJ, Marmor M

The Iliopectineal Fascia: A Cadaveric Anatomical Study.

Journal of orthopaedic trauma

Barker JP, Yang Y, Matz J, Marmor MT, Morshed S

Use of Osteobiologics for Fracture Management: The When, What, and How.

Injury

Marmor MT, Matz J, McClellan RT, Medam R, Miclau T

Management of Pelvic Ring Injury Patients With Hemodynamic Instability.

Frontiers in surgery

Marmor M, El Naga AN, Barker J, Matz J, Stergiadou S, Miclau T

Finding NEEMO: towards organizing smart digital solutions in orthopaedic trauma surgery.

EFORT open reviews

Braun BJ, Grimm B, Hanflik AM, Marmor MT, Richter PH, Sands AK, Sivananthan S

Drilling Technique Can Minimize Plunging.

Journal of orthopaedic trauma

Ding A, Marmor M

A Novel Non-invasive Method for the Detection of Elevated Intra-compartmental Pressures of the Leg.

Journal of visualized experiments : JoVE

Herring MJ, Donohoe E, Marmor MT

The influence of mini-fragment plates on the mechanical properties of long-bone plate fixation.

OTA international : the open access journal of orthopaedic trauma

Knox R, Curran P, Herfat S, Kandemir U, Marmor M

Increased litigation burden among tibia, pelvis, and spine fractures: An analysis of 756 fracture-related malpractice cases.

OTA international : the open access journal of orthopaedic trauma

Working ZM, El Naga AN, Slocum J, Tucker A, Hoogervorst P, Marmor MT

Delayed Internal Fixation of Distal Radius and Bimalleolar Ankle Fractures Does Not Increase Surgical Time.

The Open Orthopaedics Journal

Aman Chopra, Paul Hoogervorst, Meir Marmor

Smart bone plates can monitor fracture healing.

Scientific reports

Lin MC, Hu D, Marmor M, Herfat ST, Bahney CS, Maharbiz MM

Letter Regarding: Orthopaedic Trauma Association Fracture and Dislocation Classification Compendium.

Foot & ankle international

Karam MD, Agel J, Marmor M, Marsh JL, Kellam JF, Meinberg E

Simulation enabled search for explanatory mechanisms of the fracture healing process.

PLoS computational biology

Kennedy RC, Marmor M, Marcucio R, Hunt CA

Acute Shortening Versus Bridging Plate for Highly Comminuted Olecranon Fractures.

American journal of orthopedics (Belle Mead, N.J.)

Marmor M, Amano K, Yamamoto A, Friedberg D, McDonald E, Meinberg E

Increasing Bending Stiffness of Antibiotic-impregnated Cement-covered Rod Constructs.

Techniques in Orthopaedics

Meir Marmor, Moses Lee, David Friedberg, Erik McDonald

Using impedance to track fracture healing rates in mice in vivo: A pilot study.

Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference

Lin MC, Hu D, Yang F, Herfat ST, Bahney CS, Marmor M, Maharbiz MM

New opportunities for fracture healing detection: Impedance spectroscopy measurements correlate to tissue composition in fractures.

Journal of orthopaedic research : official publication of the Orthopaedic Research Society

Lin MC, Yang F, Herfat ST, Bahney CS, Marmor M, Maharbiz MM

Effect of varus and valgus alignment on implant loading after proximal femur fracture fixation.

European journal of orthopaedic surgery & traumatology : orthopedie traumatologie

Marmor M, Liddle K, Buckley J, Matityahu A

Reduction of Radiation Exposure From C-Arm Fluoroscopy During Orthopaedic Trauma Operations With Introduction of Real-Time Dosimetry.

Journal of orthopaedic trauma

Baumgartner R, Libuit K, Ren D, Bakr O, Singh N, Kandemir U, Marmor MT, Morshed S

Osteoporotic Fracture Care: Are We Closer to Gold Standards?

Journal of orthopaedic trauma

Marmor M, Alt V, Latta L, Lane J, Rebolledo B, Egol KA, Miclau T

Biomechanical comparison of long, short, and extended-short nail construct for femoral intertrochanteric fractures.

Injury

Marmor M, Elliott IS, Marshall ST, Yacoubian SV, Yacoubian SV, Herfat ST

Effect of C-Arm Year Model on Radiation Scatter.

Journal of Medical Devices

Omar Bakr, Saam Morshed, Meir Marmor

Short-term pelvic fracture outcomes in adolescents differ from children and adults in the National Trauma Data Bank.

Journal of children's orthopaedics

Marmor M, Elson J, Mikhail C, Morshed S, Matityahu A

Impedance spectroscopy to monitor fracture healing.

Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference

Lin MC, Herfat ST, Bahney CS, Marmor M, Maharbiz MM

A New Method to Intra-Operatively Measure Local Bone Strength in Osteoporotic Bone Using a Modified Surgical Tool.

Journal of Medical Devices

Kate Liddle, Jenni M. Buckley, Amir Matitiyahu, Meir Marmor

A method for detection of lateral malleolar malrotation using conventional fluoroscopy.

Journal of orthopaedic trauma

Marmor M, Kandemir U, Matityahu A, Jergesen H, McClellan T, Morshed S

The effect of fracture pattern stability on implant loading in OTA type 31-A2 proximal femur fractures.

Journal of orthopaedic trauma

Marmor M, Liddle K, Pekmezci M, Buckley J, Matityahu A

Time intervals in the treatment of fractured femurs as indicators of the quality of trauma systems.

Bulletin of the World Health Organization

Matityahu A, Elliott I, Marmor M, Caldwell A, Coughlin R, Gosselin RA

The Treatment of Acquired Patella Baja With Proximalization of the Tibial Tuberosity: Surgical Technique and Six Year Clinical Outcome.

Arthroscopy The Journal of Arthroscopic and Related Surgery

Michael Drexler, Tim Dwyer, Meir Marmor, Nikolaus Reischl, Hugh Cameron, Amir Sternheim, Fahad Gulam Attar, John Charles Cameron

Tibial Rotational Osteotomy and Distal Tuberosity Transfer for Obligatory Congenital Patella Dislocation – Surgical Technique and Seven Year Follow-Up.

Arthroscopy The Journal of Arthroscopic and Related Surgery

Michael Drexler, Tim Dwyer, De Juan Ng, Nikolaus Reischl, Meir Marmor, Fahad Gulam Attar, John Charles Cameron

Acute complications of patients with pelvic fractures after pelvic angiographic embolization.

Clinical orthopaedics and related research

Matityahu A, Marmor M, Elson JK, Lieber C, Rogalski G, Lin C, Belaye T, Miclau T, Kandemir U

Propensity for hip dislocation in normal gait loading versus sit-to-stand maneuvers in posterior wall acetabular fractures.

American journal of orthopedics (Belle Mead, N.J.)

Marmor M, McDonald E, Buckley JM, Matityahu A

Rotational malreduction of the syndesmosis: reliability and accuracy of computed tomography measurement methods.

Foot & ankle international

Knops SP, Kohn MA, Hansen EN, Matityahu A, Marmor M

Nineteen year results of THA using modular 9 mm S-ROM femoral component in patients with small femoral canals.

The Journal of arthroplasty

Drexler M, Dwyer T, Marmor M, Abolghasemian M, Chakravertty R, Chechik O, Cameron HU

Reduction of pullout strength caused by reinsertion of 3.5-mm cortical screws.

Journal of orthopaedic trauma

Matityahu A, Hurschler C, Badenhop M, Stukenborg-Colsman C, Waizy H, Wentz B, Marmor M, Krettek C

The treatment of acquired patella baja with proximalize the tibial tuberosity.

Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA

Drexler M, Dwyer T, Marmor M, Sternheim A, Cameron HU, Cameron JC

Cementless fixation in total knee arthroplasty: down the boulevard of broken dreams - opposes.

The Journal of bone and joint surgery. British volume

Drexler M, Dwyer T, Marmor M, Abolghasemian M, Sternheim A, Cameron HU

How placement affects force and contact pressure between a volar plate of the distal radius and the flexor pollicus longus tendon: a biomechanical investigation.

The Journal of hand surgery, European volume

Matityahu AM, Lapalme SN, Seth A, Marmor MT, Buckley JM, Lattanza LL

Fracture surgery of the extremities with the intra-operative use of 3D-RX: a randomized multicenter trial (EF3X-trial).

BMC musculoskeletal disorders

Beerekamp MS, Ubbink DT, Maas M, Luitse JS, Kloen P, Blokhuis TJ, Segers MJ, Marmor M, Schep NW, Dijkgraaf MG, Goslings JC, project group of the EF3X-trial

Tibial plateau fracture repairs augmented with calcium phosphate cement have higher in situ fatigue strength than those with autograft.

Journal of orthopaedic trauma

McDonald E, Chu T, Tufaga M, Marmor M, Singh R, Yetkinler D, Matityahu A, Buckley JM, McClellan RT

Bilateral heel panniculitis presenting as calcaneal osteomyelitis.

Orthopedics

Marmor M, Haim A, Drexler M, Pritsch T

Bladder exstrophy masquerading as a pelvic fracture.

Orthopedics

Haim A, Sternheim A, Drexler M, Marmor M, Steinberg EL

Pitfalls in aeromedical and ground crew engagement: lessons learned.

Military medicine

Schwartz D, Marmor MT, Geftler A, Barenboim E

Physician versus paramedic in the setting of ground forces operations: are they interchangeable?

Military medicine

Levy G, Goldstein L, Erez Y, Levite R, Bar U, Marmor M, Linn G, Onn E, Levi Y, Bar-Dayan Y

Mass medical repatriation of injured civilians after terrorist attack in Mombassa, Kenya: medical needs, resources used, and lessons learned.

Prehospital and disaster medicine

Marmor M, Goldstein L, Levi Y, Onn E, Blumenfeld A, Kosashvili Y, Levy G, Hirschorn G, Heldenberg E, Or J, Setton E, Goldberg A, Bar-Dayan Y

[Imaging of acute cervical spine trauma].

Harefuah

Parnes N, Marmor M, Gold A, Steinberg EL

Characteristics of road traffic accidents treated in an urban trauma center.

The Israel Medical Association journal : IMAJ

Marmor M, Parnes N, Aladgem D, Birshan V, Sorkine P, Halpern P