Stephen M. Howell, MD
Adjunct Professor, Department of Biomedical Engineering
University of California Davis
With more than three decades of experience as a knee surgeon, researcher, and innovator in anterior cruciate ligament (ACL) reconstruction, meniscal injury, and total knee arthroplasty (TKA), Dr. Howell’s clinical practice focuses on the treatment of sports-related injuries and degenerative processes of the knee. He performs over 500 TKRs and 100 ACL reconstructions per year.
Dr. Howell identified and reported the clinical presentations, adverse consequences, and prevention of roof impingement and PCL impingement of the ACL graft in the late 1980s and 1990s respectively. During the most recent 10 years he founded the concept of kinematic alignment for performing total knee arthroplasty. Kinematically aligned TKA has gained interest because two randomized trials and a national multicenter study showed that patients treated with kinematic alignment reported significantly better pain relief, function, flexion, a more normal feeling knee than mechanical alignment with a similar implant survivorship at 2, 3 and 6 years.
Dr. Howell is a Professor of Biomedical Engineering at the University of California, Davis. His work improving the understanding of ACL reconstruction, surgical treatment of meniscus lesions, and alignment of TKA has been fostered by a 25 year collaboration with Distinguished Professor Maury Hull PhD. In addition to their many research projects, Dr. Howell and Prof. Hull have educated and graduated 4 PhD students and 25 master students in mechanical or biomedical engineering over the past 25 years. Dr. Howell has published over 135 scientific articles in peer-review journals.
Dr. Howell frequently shares his clinical experiences and research findings as a presenter and invited speaker at national and international meetings and at universities worldwide. He regularly hosts experienced orthopedic surgeons from around the world who seek education in his techniques by observing patient care in the office, hospital, and operating room.
A member of many prestigious professional societies, Dr. Howell is a past-president of the International ACL Study Group, and a member of the American Association of Hip and Knee Surgeons, the International Society of Arthroscopy, Knee Surgery and Orthopedic Sports Medicine, the American Academy of Orthopedic Surgeons, as well as the Arthroscopy Association of North America. He is on the editorial board of the American Journal of Sports Medicine and Arthropedia.
A 1981 graduate of Northwestern University’s Feinberg School of Medicine, Dr. Howell served his internship at the Graduate Hospital of the University of Pennsylvania in Philadelphia, and completed his residency in orthopaedic surgery at Philadelphia’s Thomas Jefferson University Hospital in 1986. Before entering private practice in 1989, Dr. Howell served in the Air Force as an active duty orthopaedic surgeon at Travis AFB where he rose to the rank of Lieutenant Colonel. He completed 14 additional years as a reservist, which included a recall to active duty for Gulf War I.
Dr Howell has been honored to serve on the Editorial Board of the American Journal of Sports Medicine for the last 25 years.
Selected Published Work
Howell SM, Clark JA, Blasier RD. Serial magnetic resonance imaging of hamstring anterior cruciate ligament autografts during the first year of implantation. A preliminary study. Am J Sports Med. 1991;19(1):42-47.
Howell SM, Clark JA, Farley TE. A rationale for predicting anterior cruciate graft impingement by the intercondylar roof. A magnetic resonance imaging study. Am J Sports Med. 1991;19(3):276-282.
Howell SM, Hull ML. Aggressive rehabilitation using hamstring tendons: Graft construct, tibial tunnel placement, fixation properties, and clinical outcome. American Journal of Knee Surgery. 1998;11(2):120-127.
Howell SM, Wallace MP, Hull ML, Deutsch ML. Evaluation of the single-incision arthroscopic technique for anterior cruciate ligament replacement. A study of tibial tunnel placement, intraoperative graft tension, and stability. Am J Sports Med. 1999;27(3):284-293.
Alhalki MM, Hull ML, Howell SM. Contact mechanics of the medial tibial plateau after implantation of a medial meniscal allograft. A human cadaveric study. Am J Sports Med. 2000;28(3):370-376.
Howell SM, Gittins ME, Gottlieb JE, Traina SM, Zoellner TM. The relationship between the angle of the tibial tunnel in the coronal plane and loss of flexion and anterior laxity after anterior cruciate ligament reconstruction. Am J Sports Med. 2001;29(5):567-574.
Sekaran SV, Hull ML, Howell SM. Nonanatomic location of the posterior horn of a medial meniscal autograft implanted in a cadaveric knee adversely affects the pressure distribution on the tibial plateau. Am J Sports Med. 2002;30(1):74-82.
Simmons R, Howell SM, Hull ML. Effect of the angle of the femoral and tibial tunnels in the coronal plane and incremental excision of the posterior cruciate ligament on tension of an anterior cruciate ligament graft: an in vitro study. J Bone Joint Surg Am. 2003;85-A(6):1018-1029.
Smith CK, Howell SM, Hull ML. Anterior laxity, slippage, and recovery of function in the first year after tibialis allograft anterior cruciate ligament reconstruction. Am J Sports Med. 2011;39(1):78-88.
Howell SM, Papadopoulos S, Kuznik KT, Hull ML. Accurate alignment and high function after kinematically aligned TKA performed with generic instruments. Knee Surg Sports Traumatol Arthrosc. 2013;21(10):2271-2280.
Howell SM, Papadopoulos S, Kuznik K, Ghaly LR, Hull ML. Does varus alignment adversely affect implant survival and function six years after kinematically aligned total knee arthroplasty? International Orthopaedics. 2015:1-8.
Timo Järvelä, MD, PhD
Associate Professor of Orthopaedics and Traumatology
University of Tampere, Faculty of Medicine
Consultant Orthopaedic Surgeon, Head of the Knee Section
Sports Medicine and Arthroscopic Center
Timo Järvelä graduated from Medical School at Tampere University in 1991 and defended his PhD with an academic dissertation on ACL reconstruction with a bone-patellar tendon-bone autograft in 2001. He has been credentialed as a Specialist of Surgery (1998) and Orthopaedics and Traumatology (2000) in the University of Tampere.
He has worked as the Chief of the Day Surgery Unit in Jyväskylä Central Hospital, Chief of the Hatanpää Arthroscopic Center at Orthopaedic Department in Tampere, and Chief of the Sports Medicine Center at Hospital Mehiläinen in Tampere. Currently he is working as a Head of the Knee Section in the Sports Medicine and Arthroscopic Center at Pohjola Hospital in Helsinki.
Dr. Järvelä was selected as an EFORT (the European Federation of National Associations of Orthopaedics and Traumatology) Traveling Fellow in 1999 to Switzerland, and as an ESSKA (European Society of Sports Traumatology, Knee Surgery and Arthroscopy) Traveling Fellow in 2004 to Asia. (Singapore, Hong Kong, Japan). He completed the Sports Medicine and Visiting Research Fellowship at the Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, PA, USA, in 2001 and in 2005-2006 under the direction of Freddie Fu.
Dr. Järvelä has been as a supervisor of 3 academic dissertations and 6 theses in the field of the ACL surgery and sports medicine. Also, he has been an opponent and a reviewer of academic dissertations. He has honoured with the Best Presentation Award at the Finnish Orthopaedic Association in 2000, Best Manuscript Award at the Finnish Medical Society of Duodecim in 2006, The National Award Winning Paper at 13th Congress of European Society of Sports Traumatology, Knee Surgery and Arthroscopy (ESSKA) in 2008, and the Knee Surgery Sports Traumatology Arthroscopy (KSSTA) Best Reviewer Award in 2014.
Dr. Järvelä has published 50 papers in international peer-reviewed journals and 70 abstracts in the field of sports medicine and arthroscopic surgery. He has organized 20 international meetings and hosted 50 international fellows in his official teaching center confirmed by ESSKA and EFORT. He has also served at the Editorial Board of The American Journal of Sports Medicine and Knee Surgery, Sports Traumatology, Arthroscopy.
He has been an active member in many professional associations: Finnish Arthroscopic Association (Board member 2002-2008, President 2008-2014), ESSKA (Member at Large, Member at Arthroscopy Committee, Member at Scientific Committee, ISAKOS (Member at the Sports Medicine Committee), Member of the ACL Study Group and the Member of the Magellan Society. He has been a National Team Doctor of Finnish Triathlon Association.
Dr. Järvelä lives in Hämeenlinna with his wife, who is also MD, PhD and an Orthopaedic Surgeon. Together they have 6 children, and the 3 youngest ones are still living at home with them.
Selected Published Work
Järvelä T, Paakkala T, Kannus P, Järvinen M: The incidence of patellofemoral osteoarthritis and associated findings 7 years after an anterior cruciate ligament reconstruction with a bone-patellar tendon-bone autograft. Am J Sports Med 2001;29:18-24.
Järvelä T, Kannus P, Järvinen M: Anterior cruciate ligament reconstruction in patients with or without accompanying injuries. A re-examination of subjects 5 to 9 years after reconstruction. Arthroscopy 2001;17:818-825.
Järvelä T: Anterior cruciate ligament reconstruction with a bone-patellar tendon-bone autograft. A five- to nine -year follow-up of 101 patients. Academic Dissertation. Acta Universitatis Tamperensis 810, 2001.
Järvelä T, Paakkala T, Kannus P, Toivanen J, Järvinen M: Ultrasonographic and Power Doppler evaluation of the patellar tendon ten years after harvesting its central third for reconstruction of the anterior cruciate ligament: Comparison of patients without or with anterior knee pain. Am J Sports Med 2004;32:39-46.
Järvelä T: Double-bundle versus single-bundle anterior cruciate ligament reconstruction: a prospective, randomize clinical study. Knee Surg Sports Traumatol Arthrosc 2007;15:500-507.
Järvelä T, Moisala AS, Sihvonen R, Järvelä S, Kannus P, Järvinen M: Double-bundle anterior cruciate ligament reconstruction with hamstring autografts and bioabsorbable interference screw fixation. Prospective, randomized clinical study with 2-year results. Am J Sports Med 2008;36:290-297.
Järvelä S, Sihvonen R, Sirkeoja H, Järvelä T: All-inside meniscal repair with bioabsorbable meniscal screws or with bioabsorbable meniscus arrows: A prospective, randomized clinical study with 2-year results. Am J Sports Med 2010;38:2211-2217.
Suomalainen P, Moisala AS, Paakkala A, Kannus P, Järvelä T: Double-bundle versus single-bundle anterior cruciate ligament reconstruction: Randomized clinical and magnetic resonance imaging study with 2-year follow-up. Am J Sports Med 2011;39:1615-1622.
Suomalainen P, Järvelä T, Paakkala A, Kannus P, Järvinen M: Double-bundle versus single-bundle ACL reconstruction: Prospective, randomized study with 5-year results. Am J Sports Med 2012;40:1511-1518.
Kiekara T, Järvelä T, Moisala AS, Suomalainen P, Huhtala H, Paakkala A: Tunnel communication and increased graft signal intensity on magnetic resonance imaging of double-bundle anterior cruciate ligament reconstruction. Arthroscopy 2014:30:1595-1601.