The Sugarbush Study

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Since 1971, Dr. Robert Johnson and his team have been conducting one of the largest studies on skiing and riding injuries in the world.

On a sunny morning this past April, Dr. Robert Johnson sat on a swivel chair in front of a computer at Sugarbush’s University of Vermont Medical Center Orthopedics Clinic. Johnson, a tall figure sporting eyeglasses and a head of thick, white hair, was poring over data collected from the past few weeks. At his fingertips was a trove of information that he and his team have been collecting since 1971: comprehensive data on injuries to skiers (and, in recent decades, to riders) and analysis of how those injuries were caused. This wealth of information has informed some of the most groundbreaking studies on skiing and riding injuries and prevention in the world.

In the clinic, Johnson works with a small group of colleagues who check in and treat patients, collect information, and perform X-rays, all with a calm that mirrors Johnson’s placid demeanor. The staff moves between two large, open rooms. One room is lined with medical beds occupied by patients, often accompanied by Ski Patrol members who have escorted them down the mountain. The second room, toward the interior, is where Dr. Johnson (or his colleague of twenty-six years, Dr. Stan Grzyb) attends patients, which could involve casting a tibia fracture, wrapping a muscle, treating a shoulder or wrist dislocation, or diagnosing a potential torn anterior cruciate ligament (ACL). (Patients are also seen by orthopedic residents and fellows.) There is virtually no turnover in the clinic staff: Bobby Foster has been a medical and research assistant at Johnson’s side for close to forty years; Steve Mason, a research and X-ray technician for over twenty years; Lynne Brophy, a research assistant for seventeen years; and Carol Blair, an X-ray technician and research assistant for close to fifteen years. 

Bob Johnson grew up in Iowa Falls, Iowa. His initiation to skiing did not foreshadow a groundbreaking career in the ski industry. At age twelve he was given a six-foot-long pair of skis, slid down a hill, attempted to jump a creek, and broke the skis in half. 

Johnson graduated Phi Beta Kappa from Coe College in Cedar Rapids, Iowa, and subsequently earned a medical degree from the University of Iowa. He did not attempt to ski again until his early thirties, when he was in the Air Force, serving as chief of orthopedics at the USAF hospital on Loring Air Force Base in Maine. That second introduction to skiing resulted in a “black-and-blue bruise from my hip down to my knee,” Johnson recalls. He was going to return to Iowa after the Air Force, but the position he planned to take lost its funding, and he found himself accepting a job at the University of Vermont Medical Center. Johnson had envisioned a sports medicine career in Iowa concentrating on football, but his relocation to Vermont necessitated a change in disciplines—Vermont colleges are not known for their football teams.

Johnson began practicing orthopedic surgery at Medical Center Hospital of Vermont (now UVM Medical Center) in August of 1971. That same fall, Dr. John Saia, a family-practice doctor in the nearby Mad River Valley, suggested to Johnson that he open an orthopedic clinic in the area; at that time, the Valley had three ski areas and no clinic. In December of that year, Johnson opened shop in a partial room at Glen Ellen (now Mt. Ellen), laying the groundwork for the analysis and treatment of on-snow injuries that would come to be known as “the Sugarbush study.” Johnson began a grueling winter schedule of working at the hospital during the week and at the ski area’s orthopedic clinic on the weekends. Forty-five years later, he is still at it.

Shortly after meeting at the clinic, Johnson and I drive over to Mt. Ellen to meet one of his two key research collaborators since 1972, Carl Ettlinger. As we approach an unassuming building just past the base of the Sunny Double lift, Johnson jokes that Ettlinger has been under strict orders to “clean the place up and turn on the heat” so it is appropriate for visitors. (Comfort is not high on Ettlinger’s priority list.) The building is, in fact, three trailers fused together, and it offers sufficient space for Ettlinger to carry out his research.

Ettlinger came on the scene one year after Johnson, fresh out of a master’s program in engineering at UVM, where he had collaborated with a PhD student on the engineering of ski bindings. (Ettlinger’s own master’s thesis was entitled “On the Prevention of Ski Injuries.”) His life’s work has been devoted to analyzing the relationship between the ski boot, the binding, and the ski—and how making adjustments to those elements can influence and reduce the risk of injuries in skiing. He runs a company called Vermont Safety Research, based in Underhill. Ettlinger plays something of the “mad scientist” role in the Johnson triumvirate (the third is Jasper Shealy, a professor emeritus at Rochester Institute of Technology who holds a PhD in industrial engineering), and as he takes me on a tour of the lab where he has been conducting his research for over forty years, he talks in a steady stream, handing me pamphlets and booklets like Alpine Binding Installation and Inspection and Tips for Knee-Friendly Skiing, while listing the many programs he, Johnson, and Shealy have influenced through their work: the International Society for Skiing Safety (ISSS), the American Society of Testing and Materials (ASTM), and the International Standardization Organization (ISO), to name a few. I lose track of time in the tiny quarters, perusing part of Ettlinger’s collection of ski equipment that dates back to the 1950s, inspecting a machine called the Vermont release calibrator (the ski installation and inspection station he created), and listening to Ettlinger talk about the early days of his collaboration with Johnson and Shealy.

Shealy, known as Jake, spent his graduate school years studying the systems-engineering side of “how and why accidents occur,” and both his graduate and doctoral theses focused on ski injuries. In the Sugarbush study trio, Shealy directed the statistical analysis, Johnson presided over the orthopedic clinic, and Ettlinger collected data from both the injured and a control group. They sought information like boot height, skier foot length, boot-to-binding friction, ski length and dimension, binding release test results, and environmental conditions. All this information was used to draw conclusions on the cause of the injury—and on how it might have been prevented. In Shealy’s words, “It was only by the use of the Sugarbush study that both the medical and mechanical aspects of the injury equipment could be observed simultaneously.”

Since the early 1970s, Johnson, Ettlinger, and Shealy have published over a hundred articles, papers, abstracts, and book chapters on the prevention of ski injuries. Johnson has been awarded more than $2.5 million in research funding to study issues such as knee and ligament injuries along with ACL reconstruction and rehabilitation, from organizations like the National Institutes of Health and the Arthritis Foundation. He has been awarded more than thirty-five academic awards and honors over the course of his career, and has chaired various organizations, including the ISSS and the American Orthopaedic Society of Sports Medicine.

When Johnson and his colleagues first started in this field, the predominant injury was the broken ankle. As the sport and equipment evolved, the broken ankle was replaced by the broken tibia. Johnson and his colleagues treated the injuries, studied the data from those injuries, and drew conclusions concerning ski binding release systems and the compatibility of boots with bindings (or lack thereof). They asked questions such as: How could the injury have been prevented? Was the binding set to release properly? Did it release as it was supposed to?

Their research findings exposed a variety of scenarios. For example, some bindings were designed so that the center of rotation was inappropriately placed, preventing the binding from releasing in certain situations; other bindings were incompatible with the boot toe piece, forcing the boot and binding to jam together and prevent release. Findings like these drove Johnson, Ettlinger, and Shealy to collaborate with several other entities (including the National Ski Areas Association and Skiing magazine) to create a set of national standard ski shop practices as well as a ski shop standards course. (This “Ski and Snowboard Mechanics Workshop,” originally run by ski industry impresario Jerry Simon, was taken over by Ettlinger in 1990 and subsequently sold to SnowSports Industries America in 2015.) First released in the early 1970s, these standards contained instructions for conducting release checks on skis and boots; since the early 1990s, it has included the tuning of snowboards. Not only did the standard shop practices teach ski shop technicians how to inspect equipment to prevent injuries, the standards also began to influence the ski and binding manufacturers to make improvements in their designs. 

“Learning by doing was key,” recalls Ettlinger. “Everyone in the workshop was able to tighten the screws”—literally—“and see what it feels like to apply the necessary, but not excessive, torque to the binding.” The workshops were collaborative. Shop owners and technicians merged with binding manufacturers in an environment of shared learning. 
“The evolution of changes and upgrades to binding safety has been coming from here—from Carl and Dr. Johnson and Shealy,” says Brook Weston, owner of Mountainside Ski Service in Warren. One significant change to emerge from conclusions drawn from the Sugarbush study was the evolution of low-friction materials in binding systems, important for a consistent release of boot from binding. Weston sends his binding mechanics to Ettlinger’s workshop each year, and refers to the Alpine Binding Installation and Inspection booklet as his bible. 

Countries that follow standard shop practices—including the United States, Germany, Austria, and Switzerland—have seen a significant decrease in lower leg injuries since the 1970s. And as Johnson’s team observed in a 2009 paper, “countries that do not adhere to ISO/ASTM standards have a two- to five-fold higher risk for tibia fractures than those observed in the US.” For his work on writing ASTM standards for ski binding test devices, adjustment of alpine binding systems, and shop practices, among others, Ettlinger was presented with ASTM’s Award of Merit in 2011.

Some of the conclusions reached by Johnson and his colleagues addressed proper fitting of equipment: “Poor boot fit is a major factor leading to lower leg fracture and sprains, especially in children,” and, “Young children need the best possible equipment available.” Reading this forced me to recall the day back in 2005 when my four-year-old daughter broke her leg while skiing on Crackerjack at Mt. Ellen. How much attention had I given to her equipment fit and inspection that year—or, more truthfully, had I even had it inspected?

As boot-binding compatibility and binding release systems improved, Johnson, Shealy, and Ettlinger saw the risk of lower leg injury drop by half every six years for the first seventeen years of the study. “Early on, our goal was to prove how to get rid of the tibia fracture, the skier’s injury. We worked to show how appropriate modification of the equipment would allow it to release when it needed to,” recalls Johnson. The team concluded in a 2000 paper that there was “little doubt that the major factor in improvements [was] better designed and functioning ski boot binding systems.” 

However, as the rate of lower leg injury began to plateau, a different injury began to emerge. Johnson recalls seeing “alarming increases in rates of severe knee sprains.” The team conducted many studies where they attempted to link binding settings to ACL injuries, but overall concluded that there was no link. “Releasable bindings for Alpine skiing have helped to reduce the risk of many types of skiing-related lower leg injuries but have not been very effective in reducing the risk of injury to the ACL of the knee,” Johnson, Ettlinger, and Shealy wrote in the journal Sports Health in 2009. But the binding improvements seemed to have left the door open for a different type of injury.

So Johnson and his colleagues continued researching the problem. In the winter of 1992–93, at Sugarbush alone, Johnson and his colleagues recorded 128 ACL injuries. ACL sprains and tears, which had been creeping up each year since the late 1970s, had reached epidemic proportions. When asked how the team made headway on the ACL injury, Johnson remembers, “Carl went berserk and pestered people to death.” He refers, admiringly, to the information Ettlinger was able to uncover that allowed the team to study the injury. Ettlinger went out and conducted interviews with people who had injured their ACLs or had seen people injure them, and obtained videotapes of injuries from both ski races and relaxed family ski outings. The team analyzed the injuries Johnson was seeing in the clinic, as well as the data leading up to the injury, and made some conclusions. “We recognized two mechanisms of ACL injury: the phantom foot, and the boot induced,” recalls Johnson. The phantom foot injury can be described as the tail of the ski (the “phantom foot”) causing an ACL tear when a skier falls in a backseat position with the inside edge of the downhill ski engaged. The boot-induced injury is caused when a skier lands a jump on the tails of his skis, with knees locked and legs straight, thus causing the boot to hit the calf muscle and drive the shin forward, tearing the ACL.

That following season, Ettlinger’s team introduced an “ACL Awareness Training” program for ski patrol and ski school staff at twenty participating ski areas. The program involved instructing participants in “avoiding high-risk behavior,” “recognizing potentially dangerous situations,” and “responding quickly and effectively whenever these conditions are encountered.” Through instruction and video analysis, the participants were coached to develop a personal strategy for responding to the various scenarios for potential ACL injury. Some key components of the training to avoid injury included: don’t straighten your legs when you fall; don’t try to get up until you’ve stopped sliding; when you’re down, stay down; and try not to land on your hand. Another twenty-two ski areas were assembled to form a control group. Over the course of the three-year study, a total of 179 serious knee sprains were evaluated. ACL injuries declined by 62 percent in the study group; there was no decline in the control group.

Bob Johnson and his colleagues have spent over half their lives studying skiing injuries, shop practices, tibial plateau fractures, and ACL sprains; in recent years they’ve started examining riding injuries and helmet usage as well. The Sugarbush study, which they began in 1971, is still going strong. This past spring, friends and colleagues gathered at Sugarbush’s Gate House Lodge to honor Johnson for the work he has contributed to the industry. Several hundred people filled the room.

Win Smith, president of Sugarbush, thanked Johnson for the remarkable contribution he has made to the sport. Parker Riehle, president of the Vermont Ski Areas Association, presented to Johnson, on behalf of the National Ski Areas Association, an Impact Award, for his “substantial contribution to NSAA and the ski industry.” Jake Shealy and Carl Ettlinger gave a presentation identifying the highlights of their team’s research over the years: their study has spanned more than eight million skier visits and almost 30,000 injuries, and they estimated that the Sugarbush study, by leading to specific steps to avoid injury, has saved American skiers tens of billions of dollars in medical expenses—not to mention saving them from the pain and inconvenience of an injury.

Perhaps most telling of all were the personal tributes from Johnson’s longtime colleagues on the clinic staff. Bobby Foster spoke first, poking fun at himself for having been hired “only because the attractive woman in the bar who was offered the job didn’t show up.” He then went on to tell of his default responsibility of informing Johnson of staff antics “the mountain” may have been concerned with, such as a bikini-clad medical student sunbathing on a gurney outside the clinic. Other staff members followed Foster, laughing as they told stories about working with Johnson, who has characterized his career as “a hobby that went out of control.”

It wasn’t so much what Johnson’s colleagues said, but more the emotions they struggled to keep in check when they spoke. It was clear to the crowd in the room that Johnson’s work has benefited not just the thousands of patients he has treated through the years, but also the committed team that has dutifully surrounded him for decades. To have made an impact on an industry to the extent that Johnson and his colleagues have influenced skiing is remarkable; to have done it in a manner that is compassionate and fun is of another level entirely.


The research trailers at Mt. Ellen


The original testing equipment 


Ettlinger's son, Kris, demonstrates how to use the Vermont release calibrator.


Ettlinger and Johnson analyze a ski binding.