Years ago, Frank R. Noyes, MD, began investigating why knee ligament reconstruction after injury to the anterior cruciate ligament (ACL) failed to restore knee stability in many patients. Even after revision surgery, these patients—most of them young—still had pain and limited activity.


Published 7/1/2009
Kathleen Louden

ACL research helps surgeons deliver better results

Efforts of OREF Award recipient effect shift in treatment

With approximately 100,000 ACL reconstruction surgeries performed each year in the United States, the need for ACL revision surgery is problematic. Although success rates for ACL reconstruction range from 80 percent to 90 percent of patients, a significant number of ACL reconstructions performed each year fail and require revision procedures.

Dr. Noyes found that approximately one-third of his patients who needed ACL revision surgery had an unrecognized associated problem, usually genu varum (bowed legs) or deficiency of the posterolateral ligament structures, or both (Fig. 1). He and his co-investigators hypothesized that all damaged portions of the posterolateral ligament complex require surgical repair or reconstruction and that osseous lower limb malalignment must be corrected (with a high tibial osteotomy) before ACL reconstruction, or the chances that reconstruction would fail would increase.

Beginning in the mid-1980s, the researchers performed biomechanical, gait-analysis, and clinical outcomes studies that proved their hypothesis; the results were published in 27 articles.

“Now it’s well known, but then it represented a major shift in treatment,” said Dr. Noyes, who is chairman and medical director of the Cincinnati SportsMedicine and Orthopaedic Center and a volunteer professor of orthopaedic surgery at the University of Cincinnati.

Groundbreaking clinical studies, conducted by Dr. Noyes and his team over nearly two decades, changed how orthopaedic surgeons treat patients who have both lower limb malalignment and knee ligament injuries.

“For the first time, the medical community had a documented success rate in restoring stability in these complex knees,” said Dr. Noyes.

In recognition of this work, Dr. Noyes won the 2004 Orthopaedic Research and Education Foundation (OREF) Clinical Research Award with his colleagues Edward S. Grood, PhD, professor of biomedical engineering at the University of Cincinnati; Thomas P. Andriacchi, PhD, professor of mechanical engineering and orthopaedic surgery at Stanford University, Stanford, Calif.; and Sue Barber-Westin, BS, director of clinical studies at the Cincinnati SportsMedicine Research and Education Foundation, a nonprofit organization that

Dr. Noyes created in 1985. The Clinical Research Award provides $20,000 to recognize outstanding original clinical research related to musculoskeletal disease or injury.

Collaboration between physician and engineering researchers was important to the success of their work, he commented.

“We combined years and years of biomechanical studies and data analysis to come up with the pieces of the puzzle so that we could do the clinical research,” Dr. Noyes said. Drs. Noyes and Grood established one of the first biomechanical research laboratories in the country within the Department of Engineering at the University of Cincinnati in the late 1970s. The laboratory is now known as the Noyes Tissue Engineering and Biomechanics Laboratory.

OREF-funded pilot studies
In early studies, Drs. Noyes and Grood measured the biomechanical properties of healthy human knee ligaments and defined their functions. They reported that one or two ligaments provide what they called the primary restraint for each of the six degrees-of-freedom or planes of knee stability, with the remaining ligaments having a secondary, helping role. These pilot studies were supported by an OREF Research Grant in 1976.

Years ago, Frank R. Noyes, MD, began investigating why knee ligament reconstruction after injury to the anterior cruciate ligament (ACL) failed to restore knee stability in many patients. Even after revision surgery, these patients—most of them young—still had pain and limited activity.
Fig. 1 Patient with severe knee hyperextension, varus recurvatum, lower limb osseous varus malalignment, posterolateral ligament deficiency, and anterior cruciate ligament deficiency.
Courtesy of Frank R. Noyes, MD
Fig. 3 The calculations at the time of opening wedge high tibial osteotomy to determine the opening gap. Y2 should be half of Y1 to maintain normal tibial slope.
Courtesy of Frank R. Noyes, MD
Fig. 4 Anteroposterior radiograph following an opening wedge osteotomy. An iliac crest bone graft and locking plate with screws were used in the procedure.
Courtesy of Frank R. Noyes, MD

“We appreciate OREF,” said Dr. Noyes. “As a result of those pilot studies, we were able to obtain major funding over 15 years from the National Institutes of Health, and we established the scientific merit of the approach that we were taking.”

Dr. Noyes’ team improved the diagnosis and classification of knee ligament injuries. First, they performed biomechanical and kinematic (body-motion measurement) analyses of a battery of tests that clinicians used to diagnose ligament injuries. The researchers recommended ways that physicians could increase their accuracy in performing and interpreting the results of clinical tests.

For example, at the time, physicians interpreted knee joint laxity tests based on clinical impressions. Dr. Noyes and his colleagues provided objective data as to which ligament structures were injured, enabling test results to be more accurately interpreted.

In 1983, the researchers developed the Cincinnati Knee Rating System, which uses subjective, objective, and functional criteria to analyze patient complaints and surgical outcomes. Now one of the most widely used knee rating systems, it provided a more valid and scientific basis of evaluation than was possible with previous rating systems, according to Dr. Noyes.

“Most of the rating systems that were available then were not comprehensive enough to detect the clinical outcome,” he said.

The investigators also developed a classification system known as the primary, double, or triple varus knee, which accounted for the osseous malalignment and ligament defects (Fig. 2). Surgeons can use this classification system in making treatment decisions about the surgical procedures required to restore stability and function to the knee.

Preoperative measurement techniques developed by Dr. Noyes’ team enable surgeons to determine the magnitude of the osteotomy correction required in patients with varus deformity (Fig. 3).

Finally, the scientists gave surgeons an algorithm to select the appropriate procedure for posterolateral ligament reconstruction when required. Based on biomechanical and clinical outcomes studies, they defined several different surgical techniques to restore posterolateral stability to the knee joint (Fig. 4). In prospective clinical trials beginning in the mid-1980s, they captured long-term follow-up data for more than 90 percent of patients, with some studies achieving 100 percent follow-up, Dr. Noyes said. Depending on the type of ligament surgery used, the authors reported success rates ranging from 80 percent to 92 percent.

Life-changing research
Dr. Noyes said their research has enabled surgeons to provide good results in patients with complex knee problems.

“We help these individuals maintain their active lifestyles. It has a tremendous impact on their lives,” he said.

In the past 15 years, Dr. Noyes created the nonprofit Sportsmetrics women’s knee ligament injury prevention program. The program—6 weeks of neuromuscular retraining and conditioning—is now offered in more than 600 cities in the United States. The scientific basis for the Sportsmetrics program and the results of the training have appeared in numerous peer-reviewed publications. Thomas N. Lindenfeld, MD, and Timothy E. Hewett, PhD, have received OREF funding to determine the effects of estrogen on jump-landing forces in the female knee joint.

Dr. Noyes said he appreciates that OREF funds all types of orthopaedic research, including sports medicine. An OREF Shands Circle member, he said, “It’s the one foundation that supports all of orthopaedics.”

Kathleen Louden is a contributing writer for OREF and can be contacted at