High tibial osteotomy (HTO) slows articular cartilage damage in individuals with bowlegs and medial compartment knee osteoarthritis (OA) compared to nonsurgical management alone, according to a new study.
Patients who underwent HTO also reported less pain and higher overall knee function.
“To our knowledge, this is the first study to show that a treatment for knee OA can modify the natural course of disease, by both slowing joint damage and improving symptoms at 2-years follow-up,” said lead author Trevor Birmingham, PhD, a professor and Canada Research Chair in Musculoskeletal Rehabilitation at the University of Western Ontario, London, Ontario, Canada. “It supports the use of HTO for this common subgroup of patients.”
Varus alignment, or bowlegs, is a risk factor for both the development and progression of knee OA, Birmingham explained. Medial opening wedge HTO is a limb realignment surgery with the goal of changing the biomechanics of the knee to help preserve the joint. The procedure is less commonly performed in North America than in other countries, particularly in Asia and Europe, he said.
The study, conducted at the Fowler Kennedy Sport Medicine Clinic in London, Ontario, enrolled patients with varus alignment and radiographic knee OA primarily affecting the medial tibiofemoral compartment. Patients were randomly assigned to receive either HTO plus nonsurgical management or nonsurgical management alone. All participants followed a 3-month structured exercise program that included a 1-hour in-person training session and three independent home workouts each week. Participants also received nutrition counseling throughout the study.
The trial included a parallel preference arm for patients in which patients selected their preferred treatment.
Researchers measured changes in articular cartilage thickness in the medial tibiofemoral compartment from baseline to 2-year follow-up as well as change in the total Knee Injury and Osteoarthritis Outcome Score (KOOS).
The study was published July 28 in Annals of Internal Medicine.
‘Realignment Will Help Preserve the Joint’
A total of 124 patients completed the study through 2-year follow-up. Of the 59 patients in the randomized arm, 30 were assigned to the HTO plus nonsurgical management arm and 29 to a control arm of nonsurgical management alone. Patients were in their mid-fifties and the majority were male. The average BMI was between 30 and 31, and the mean duration of knee symptoms was about 7 years.
HTO appeared to slow progression of knee OA; at 2 years, the mean change in medial tibiofemoral articular cartilage thickness in the HTO group was -0.07 mm (loss of 2% from baseline) and -0.25 mm in the control group (loss of 9% from baseline), a difference of 0.18 mm. The authors noted that the suggested minimal clinically important difference for the loss of medial tibiofemoral articular cartilage thickness is 6.3%.
The change in total KOOS was 24.95 points in the HTO group and 9.06 points in the control group, with a mean difference of nearly 16 points.
The parallel preference arm had similar results. The 36 patients who selected HTO had less deterioration of medial tibiofemoral articular cartilage and greater change in total KOOS than the 29 patients who received only nonsurgical management.
Five of the participants who received HTO (both randomized and parallel arms combined) required additional surgery because of an adverse event.
“The study brings awareness to a very, very important truth in orthopedics, which is [that] realignment will help preserve the joint,” said S. Robert Rozbruch, MD, chief of the Limb Lengthening and Complex Reconstruction Service, and director of the Osseointegration Limb Replacement Center at Hospital for Special Surgery in New York City. He was not involved with the study.
While this study found a positive effect in middle-aged patients with moderate arthritis, younger patients with less severe arthritis due to varus alignment will benefit most from this surgery, he continued. For these patients, HTO could potentially alter the natural course of the disease, and total knee replacement may never be needed, he said.
The study findings have wider implications as well, added Birmingham. “It shows that if you improve unfavorable biomechanics at the joint, it leads to long-term clinically important benefits,” he said. “Hopefully, that helps with other treatments as well, [providing] some promise that we can actually get in there and intervene.”
The Canadian Institutes of Health Research, Arthritis Society Canada, and Bernard & Norton Wolf Family Foundation provided funding for this research. Birmingham had no relevant disclosures. Rozbruch reported consulting for Johnson & Johnson, NuVasive, OrthoSpin, and Ostesys; receiving royalties from NuVasive; participating in a speakers bureau for Johnson & Johnson; and having ownership interest in several companies, including HS2, HSS ASC Development Network, Joint Effort ASO, OrthoSpin, Ostesys, and RGD Soleforce, where he also serves as a board member.