In Memoriam—Gunnar B.J. Andersson, MD, PhD

Anyone who sat through a scientific session on low back pain during the past 4 decades will recognize the pattern. A speaker would put up a number—a prevalence, a cost, a rate of surgery, a fusion outcome—and from somewhere near the front a tall Swede would reach the microphone and ask, courteously and without a trace of malice, where the number had come from. That question, and the incisiveness and exacting good humor with which it was always asked, will be heard no more. Gunnar B. J. Andersson, MD, PhD, The Ronald L. DeWald, MD, Professor and Chairman Emeritus of the Department of Orthopedic Surgery at Rush University Medical Center, Chicago, Illinois, and a past president of the International Society for the Advancement of Spine Surgery (ISASS), has died at the age of 84 years.

 Many readers of the International Journal of Spine Surgery will remember Gunnar for his presence at meetings that spanned every habitable continent and half a century. He asked the question everyone else was thinking but had not framed precisely enough. His comments returned a presentation to its evidence. His criticisms were delivered constructively and almost always with a route out of the difficulty—a better analysis, a missing control, literature the presenter had not yet found. For the many of us he trained, sponsored, co-authored with, and argued with, this loss is personal as well as professional.

EDUCATION AND CAREER HIGHLIGHTS

Gunnar was born in Sweden in 1942. He received his medical degree from the University of Göteborg in 1967 and completed his orthopedic residency at Sahlgren University Hospital. As he liked to remind younger colleagues, his ambition was to become a joint replacement surgeon, particularly after observing the legendary John Charnley perform early total hip replacement procedures with uncanny speed and accuracy. However, he was diverted by a question that in the late 1960s had scarcely been asked properly: what actually loads the human lumbar spine, and by how much? He obtained a PhD in medical science from the University of Göteborg in 1974 with a thesis on myoelectric back muscle activity and lumbar disc pressure in sitting postures, completed a fellowship at The London Hospital, and remained on the Göteborg faculty for 10 years.

He first came to the United States in 1976 on a research fellowship and returned permanently in 1985, joining Rush University Medical Center as professor of orthopedic surgery. He was appointed Chairman of the Department of Orthopedic Surgery in 1994 and held that position until 2008; during those years, he also served as president of the Medical Staff, as vice dean for Surgical Sciences and Services, and as senior vice president of Medical Affairs. He was named The Ronald L. DeWald, MD, Professor, practiced with Midwest Orthopaedics at Rush, and retired from clinical practice in 2015—after which he remained fully active in research, editorial work, health policy, and industry advisory roles.

His editorial service was extensive even by the standards of a long career. He was a deputy editor of Spine, the founding editor of Contemporary Spine Surgery, editor-in-chief of Spinal News International, and an associate editor of Clinical Biomechanics, and he sat on 17 editorial boards. He authored more than 360 original articles, some 170 books and book chapters, and more than 550 abstracts.

He assumed numerous leadership roles. He was president of the Orthopaedic Research Society (ORS), of the International Society for the Study of the Lumbar Spine, of the American Academy of Disability Evaluating Physicians, and of ISASS. He served as a council member of the National Institute of Arthritis and Musculoskeletal and Skin Diseases, chaired the Research Committee of the American Academy of Orthopaedic Surgeons, and served on 3 Institute of Medicine committees. His honors included the Kappa Delta Award of the American Academy of Orthopaedic Surgeons and ORS, the Muybridge Medal of the International Society of Biomechanics, the Lifetime Achievement Award of the ISSLS, the Alfred R. Shands Jr, MD, Award and Lecture of the ORS, the Henry Farfan Award of the North American Spine Society, the Freedom of Movement Award of the Arthritis Foundation, and the Trustee Medal of Rush University Medical Center. He was elected to the College of Fellows of the American Institute for Medical and Biological Engineering.

 LOADING THE HUMAN SPINE

The Göteborg department Gunnar joined, under Alf Nachemson, had begun to answer the loading question in the most direct way then available: by placing pressure transducers into the intervertebral discs of living volunteers. Nachemson had established that the disc behaved hydrostatically and that intradiscal pressure rose with applied compression. Gunnar’s contribution was to carry the method out of the laboratory and into the postures in which people actually spend their days.

With Roland Örtengren, Nachemson, Gösta Elfström, and Holger Broman, he measured intradiscal pressure and paraspinal myoelectric activity simultaneously across standing and a wide range of seated positions, and then in the office chair, the wheelchair, and the driver’s seat of a car. The resulting series, 4 articles in the Scandinavian Journal of Rehabilitation Medicine in 1974, and the work that followed in Spine and Clinical Orthopaedics and Related Research, established quantitatively what clinicians had only suspected: that unsupported sitting loads the lumbar disc more heavily than standing; that forward flexion raises that load sharply; and that backrest inclination and lumbar support relieve

it in a predictable, dose-dependent way.

It is difficult now to appreciate how consequential this was. It moved the seated worker out of anecdote and into biomechanics; it gave ergonomics a dependent variable it could defend, and it is why Gunnar spent the rest of his life being cheerfully credited with having designed the seat in a Volvo. The lumbar support in the chair most readers of this journal are sitting in is a descendant of that work.

 FROM THE LABORATORY TO THE WORKPLACE

The natural extension was occupational. Working with Albert Schultz and others, Gunnar validated bio-mechanical models of spinal loading against the intra-discal pressures and myoelectric signals he had spent a decade learning to measure—a 1982 Journal of Bone and Joint Surgery article that gave the field confidence a model could stand in for a transducer. He examined intra-abdominal pressure, lifting posture, whole-body vibration, and the relationship between occupational exposure and back complaints.

That work found its lasting form in Occupational Biomechanics, written with Don Chaffin and Bernard Martin. It ran to 5 editions, the most recent in 2023, and became the standard graduate text in the field. It was read far more widely by industrial engineers and ergonomists than by spine surgeons, which Gunnar considered entirely appropriate. Very few spine surgeons have had that kind of reach outside medicine, and fewer still have sustained it across 4 decades.

 THE EPIDEMIOLOGY OF BACK PAIN

Gunnar’s third research stream reached furthest beyond our own community. He was among the first orthopedic surgeons to treat back pain as a population-level phenomenon rather than a purely clinical one, and to insist that the field’s claims about prevalence, cost, and practice variation be sourced rather than repeated. His Swedish cohort studies of low back pain in working men and women through the 1980s were early, careful, and much imitated.

The synthesis came in 1999, when The Lancet published “Epidemiological features of chronic low-back pain.” It remains among the most-cited articles ever written on the subject, with more than 3000 citations, and it is still the reference of first resort when anyone needs a defensible statement of how common chronic back pain is, what it costs, and how differently it is treated from 1 country to the next. He wrote the epidemiology chapters for Frymoyer’s The Adult Spine, and he was a contributing author to The Burden of Musculo-skeletal Diseases in the United States, the United States Bone and Joint Initiative’s long campaign to give musculoskeletal disease the epidemiological standing that cancer and cardiovascular disease had long enjoyed.

 THE DISC AND THE DISCIPLINE OF EVIDENCE

At Rush, he built and led a National Institutes of Health program project on disc degeneration, and his laboratory’s output on disc biology, annular mechanics, facet loading, endplate morphology, and the imaging correlates of degeneration continued well past his retirement from clinical practice.

He was equally willing to turn that rigor on treatments the field wanted to believe in. His 2006 systematic review with Nagy Mekhail and Jon Block of spinal fusion and intradiscal electrothermal therapy for intractable discogenic low back pain reached conclusions the market did not wish to hear, and he published them. He did the same, with Frank Phillips, on lumbar fusion for degenerative disc disease. He was no nihilist about intervention. He spent his last 2 decades helping to get effective procedures coded and covered, but he held that a therapy earns its place by evidence rather than by enthusiasm, and he said so in public, repeatedly, to audiences that included his friends.

 BUILDING A DEPARTMENT

Gunnar’s most durable institutional achievement is a department. What he built at Rush between 1994 and 2008 was a private-practice clinical model sustained inside an academic medical center without surrendering either the teaching or the research mission. He recruited deliberately, protected the laboratory through lean years, and built a dedicated orthopedic office building on the Rush campus so that patients and surgeons had a home.

Asked on his retirement in 2015 what he was proudest of, he named exactly that, and then added, characteristically, that it was not his doing but the department’s. It was, in fact, largely his doing. Generations of Rush residents and spine fellows, several of them now leading departments of their own, are the more visible legacy.

 ISASS, POLICY, AND ACCESS TO CARE

For this society and this journal, the last chapter of his career may matter most. Gunnar came to ISASS as vice president and treasurer, assumed the presidency in 2014, and chaired the Public Policy Committee—a role that suited him precisely because it demanded someone willing to read a coverage policy with the same skepticism he brought to a scientific abstract. He also served as vice-chair of International Advocates for Spine patients.

He was central to the coding and coverage work that has become among the Society’s most concrete contributions to patients. With several of the present authors, he helped secure a specific ICD-10-CM code for lumbar discogenic pain, a change that sounds administrative and is not, because a diagnosis that cannot be recorded cannot be counted, studied, tracked, or reimbursed. He contributed to the ISASS and Society for Minimally Invasive Spine Surgery survey work on minimally invasive sacroiliac joint fusion that informed subsequent coverage arguments, and he contributed to the societies’ position statements across a decade. He understood earlier than most surgeons of his generation that a treatment that cannot be coded, covered, and measured does not reach patients, however sound its biology.

He was still contributing at the end. Among his last articles, written with colleagues from this society, were a review of infection in total disc replacement and an account of the evolving spine code landscape, a fair summary of a career spent moving between the laboratory bench and the payer’s desk, and equally at home at both.

 LIFE BEYOND THE SPINE

Gunnar remained deeply Swedish and deeply Chicagoan at once. He served as co-chair of the board of trustees of the Swedish American Museum and was an active figure in Chicago’s Swedish American community for decades. His humor was dry, delivered without any change of expression, and routinely missed by people who had not yet learned to watch for it.

He had a formidable memory, which he once described, accurately, as “a 30/30 memory, meaning I remember everything from 30 years ago and everything from the last 30 seconds.” Colleagues learned not to misstate a result in front of him. Trainees learned something better: that he would tell them a study was not good enough, and then spend an hour explaining how to make it good enough. He was that rare senior figure whose approval was difficult to obtain and therefore worth having.

CLOSING

The field of spine care as it now exists—evidence-graded, epidemiologically literate, arguing about out-comes rather than asserting them, and increasingly able to make its case to those who pay for care—is in no small part the field Gunnar Andersson insisted upon. He entered it when back pain was still largely a matter of clinical opinion, and he left it a quantitative discipline. Gunnar was the personification of the familiar idiom “a gentleman and a scholar.” Those of us who had the privilege of working with him will remember the rigor.

 We will remember the kindness underneath it rather longer.

Funding: The authors received no financial support for the research, authorship, and/or publication of this article.

Declaration of Conflicting Interests: Drs. Yuan, Hochschuler, Phillips, Garfin, and Lorio are past presidents of ISASS. Dr. Harrop is the editor in chief of this journal.

Author Contributions: Hansen A. Yuan: Conceptualization, writing—original draft, and writing—review and editing. Stephen Hochschuler: Conceptualization, writing—original draft, and writing—review and editing. Frank Phillips: Conceptualization, writing—original draft, and writing—review and editing. Steven R. Garfin: Conceptualization, writing—original draft, and writing—review and editing. Howard S. An: Conceptualization, writing—original draft, and writing—review and editing. Morgan P. Lorio: Conceptualization, writing—original draft, and writing—review and editing. James S. Harrop: Conceptualization, writing—original draft, and writing—review and editing. Jon E. Block: Conceptualization, writing—original draft, and writing—review and editing.

Corresponding Author: Jon E. Block, Independent Consultant, 2210 Jackson St, Suite 401, San Francisco, CA, USA; jb@drjonblock.com

Hansen a. Yuan, MD1; Stephen Hochschuler, MD2; Frank Phillips, MD3; Steven R. Garfin, MD4; Howard S. An, MD5; Morgan P. Lorio, MD, Facs6; James S. Harrop, MD7; and Jon E. Block, PʜD8

1Professor Emeritus, SUNY Upstate Medical University, Syracuse, NY, USA; 2Texas Back Institute (Retired), Plano, TX, USA; 3Division of Spine Surgery, Rush University Medical Center, Chicago, IL, USA; 4University of California San Diego School of Medicine (Retired), San Diego, CA, USA; 5Professor Emeritus, Rush Medical College, Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, IL, USA; 6Orlando College of Osteopathic Medicine, Winter Garden, FL, USA; 7Departments of Neurological and Orthopedic Surgery, Thomas Jefferson University, Philadelphia, PA, USA; 8Independent Consultant, San Francisco, CA, USA

Selected publications by Gunnar Andersson.

Selected Publications, in Chronological Order

• Andersson BJG, Örtengren R. Lumbar disc pressure and myoelectric back muscle activity during sitting. II. Studies on an office chair. Scand J Rehabil Med. 1974;6(3):115–121.

• Andersson BJG, Örtengren R. Lumbar disc pressure and myoelectric back muscle activity during sitting. III. Studies on a wheelchair. Scand J Rehabil Med. 1974;6(3):122–127.

• Andersson GBJ. On myoelectric back muscle activity and lumbar disc pressure in sitting postures [thesis]. Göteborg, Sweden: Gotab; 1974.

• Andersson GBJ, Örtengren R, Nachemson A. Intradiscal pressure, intra-abdominal pressure and myoelectric back muscle activity related to posture and loading. Clin Orthop Relat Res. 1977;(129):156–164.

• Andersson GBJ, Murphy RW, Örtengren R, Nachemson AL. The influence of backrest inclination and lumbar support on lumbar lordosis. Spine. 1979;4(1):52–58.

• Schultz AB, Andersson GBJ, Örtengren R, Nachemson A, Haderspeck K. Loads on the lumbar spine: validation of a biomechanical analysis by measurements of intradiscal pressures and myoelectric signals. J Bone Joint Surg Am. 1982;645:713–720.

• Svensson HO, Andersson GBJ, Johansson S, et al. A retrospective study of low back pain in 38- to 64-year-old women. Frequency of occurrence and impact on medical services. Spine. 1988;135:548–552.

• Andersson GBJ. The epidemiology of spinal disorders. In: Frymoyer JW, ed. The Adult Spine: Principles and Practice. 2nd ed. Philadelphia, PA: Lippincott-Raven; 1997:93–141.

• Andersson GBJ. Epidemiological features of chronic low-back pain. Lancet. 1999;354(9178):581–585.

• Andersson GB, Mekhail NA, Block JE. Treatment of intractable discogenic low back pain. A systematic review of spinal fusion and intradiscal electrothermal therapy (IDET). Pain Physician. 2006;9(3):237–248.

• Chaffin DB, Andersson GBJ, Martin BJ. Occupational Biomechanics. 4th ed. Hoboken, NJ: John Wiley & Sons; 2006.

• Lorio MP, Polly DW, Ninkovic I, Ledonio CGT, Hallas K, Andersson G. Utilization of minimally invasive surgical approach for sacroiliac joint fusion in surgeon population of ISASS and SMISS membership. Open Orthop J. 2014;8:1–6.

• Martin BJ, Nussbaum MA, Andersson GBJ. Chaffin’s Occupational Biomechanics. 5th ed. Hoboken, NJ: John Wiley & Sons; 2023.

• Lorio MP, Yuan HA, Beall DP, Block JE, Andersson GBJ. The role of ISASS in evolving the spine code landscape: lumbar discogenic pain receives a specific ICD-10-CM code. Int J Spine Surg. 2024;184:353–354.

• Spece H, Khachatryan A, Phillips FM, Lanman TH, Andersson GBJ, Garrigues GE, Bae H, Jacobs JJ, Kurtz SM. Presentation and management of infection in total disc replacement: a review. N Am Spine Soc J. 2024;18:100320.

Published 11 September 2026

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