Jonathan Chen Sum, BS

Associate Professor Of Clinical Physical Therapy

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Dr. Jonathan Sum is the Director of USC Physical Therapy Associates on the Health Sciences Campus, the faculty practice for the USC Division of Biokinesiology and Physical Therapy. He specializes in treating patients with orthopedic disorders, sports related injuries, post-surgical rehabilitation, pain management, and musical performance related injuries. Dr. Sum is double board certified by the American Board of Physical Therapy Specialties, both as an Orthopedic Clinical Specialist, and a Sports Clinical Specialist. He is a member of the Orthopedic Section and the Sports Section of the American Physical Therapy Association. He is also a Certified Strength and Conditioning Specialist, and a member of the National Strength and Conditioning Association.

Dr. Sum is an Instructor of Clinical Physical Therapy in the USC Division of Biokinesiology and Physical Therapy. He teaches in the Doctor of Physical Therapy program where he coordinates the shoulder complex module for the patient management courses in the first year. He is also a faculty mentor in the Orthopedic Physical Therapy residency program and the Sports Physical Therapy residency program at USC. For the Keck School of Medicine of USC, Dr. Sum instructs the musculoskeletal examination labs for the Introduction to Clinical Medicine courses, and has guest lectured for the Thornton School of Music. He has also been a returning guest panelist for the Kinesiology Club.

Along with his clinical and academic pursuits, Dr. Sum has also been published in the International Journal of Sports Physical Therapy, and has been an invited speaker at several local, state, and national conferences. He has been involved with research studying the lumbar spine and the shoulder complex, as well as examining jazz guitarists. Dr. Sum also assists with pre-season physicals for the Los Angeles Angels of Anaheim professional baseball club during Cactus League Spring Training every year.


  • Hip Abductor Strength Asymmetry: Relationship to Upper Extremity Injury in Professional Baseball Players Sports Health. 2023 Mar-Apr; 15(2):295-302. . View in PubMed
  • Proposed Musculoskeletal Examination of Youth and Adolescent Baseball Players Curr Sports Med Rep. 2022 Oct 01; 21(10):376-382. . View in PubMed
  • Professional Baseball Player Type and Geographic Region of Origin Impacts Shoulder External and Internal Rotation Strength Int J Sports Phys Ther. 2021; 16(4):1126-1134. . View in PubMed
  • Little League Shoulder in a 15-Year-Old Male Baseball Pitcher J Orthop Sports Phys Ther. 2018 01; 48(1):51. . View in PubMed
  • Observational Scapular Dyskinesis: Known-Groups Validity in Patients With and Without Shoulder Pain J Orthop Sports Phys Ther. 2017 Aug; 47(8):530-537. . View in PubMed
  • Perioperative Testosterone Supplementation Increases Lean Mass in Healthy Men Undergoing Anterior Cruciate Ligament Reconstruction: A Randomized Controlled Trial Orthop J Sports Med. 2017 Aug; 5(8):2325967117722794. . View in PubMed
  • Promoting physical therapists’ use of research evidence to inform clinical practice: part 3–long term feasibility assessment of the PEAK program BMC Med Educ. 2016 May 12; 16:144. . View in PubMed
  • Pelvic osteomyelitis presenting as groin and medial thigh pain: a resident’s case problem J Orthop Sports Phys Ther. 2015 Apr; 45(4):306-15. . View in PubMed
  • Randomized control trial to evaluate the effects of acute testosterone administration in men on muscle mass, strength, and physical function following ACL reconstructive surgery: rationale, design, methods BMC Surg. 2014 Dec 06; 14:102. . View in PubMed
  • Promoting physical therapists’ use of research evidence to inform clinical practice: part 2–a mixed methods evaluation of the PEAK program BMC Med Educ. 2014 Jun 25; 14:126. . View in PubMed
  • Superior labrum anterior-to-posterior tear J Orthop Sports Phys Ther. 2012 Dec; 42(12):1050. . View in PubMed
  • Osteochondritis dissecans J Orthop Sports Phys Ther. 2011 Oct; 41(10):796. . View in PubMed
  • Physical therapy intervention for a former power lifter after arthroscopic microfracture procedure for grade iv glenohumeral chondral defects Int J Sports Phys Ther. 2011 Mar; 6(1):10-26. . View in PubMed