Feb. 7, 2019

Study highlights importance of ACL reconstruction for youth at high risk of knee reinjury

Sport Medicine Centre researchers find patellar tendon reconstruction can protect active youth from early osteoarthritis
Nick Mohtadi, left, led a clinical trial with Dana Hunter, centre, research assistant, and Denise Chan, research co-ordinator, investigating anterior cruciate ligament (ACL) reconstruction for youth at high risk of knee reinjury. Photo by Riley Brandt, University of Calgary
Nick Mohtadi, left, led a clinical trial with Dana Hunter, centre, research assistant, and Denise Ch

Anterior cruciate ligament (ACL) rupture, one of the most common types of knee injury, usually affects active, young adults, and requires reconstructive surgery to regain knee stability.

A new randomized clinical trial by researchers at the Faculty of Kinesiology’s Sport Medicine Centre measured the outcomes of patients at five years after receiving ACL reconstructive surgery with one of three different graft types. The graft is a piece of tendon from either the patient’s own patellar tendon (which attaches the kneecap to the shin bone) or hamstring muscle.

The study shows that a patient’s quality of life is the same at five years, regardless of the graft type used. However, the study also shows that ACL reconstruction with a specific graft type, patellar tendon, is recommended for younger patients who have a high risk of reinjury. Previously, ACL reconstruction was guided by the surgeon’s choice, “Dr. Google,” and sometimes patient preference, with inconclusive scientific evidence to support the optimal graft choice.

Pictured above are Nick Mohtadi, left, who led a clinical trial with Dana Hunter, centre, research assistant, and Denise Chan, research co-ordinator.

Preventing earlier onset of osteoarthritis

“This study has taught us to focus on young athletes who play sports like football, basketball and soccer, and graft type makes a difference in these high-risk individuals. Even more important is protecting the menisci (cartilage shock absorbers). Young, active patients who have ACL tears that are untreated typically damage their menisci, leading to the chance of earlier osteoarthritis development,” says Dr. Nicholas Mohtadi, MD, medical director of the Sport Medicine Centre; clinical professor, Department of Surgery, Cumming School of Medicine; adjunct professor, Faculty of Kinesiology; and McCaig Institute for Bone and Joint Health.

A ligament is a structure that joins two bones, and in a way, the patellar tendon is more like a ligament because it joins the kneecap to the shin bone.

This randomized clinical trial compares patient outcomes following ACL reconstruction with either a patellar tendon, single-bundle hamstring tendon, and double-bundle hamstring tendon graft. 

Five-year clinical trial has 'remarkable' followup rate

Three-hundred-and-thirty patients were randomly assigned to undergo one of these three procedures. The disease-specific Anterior Cruciate Ligament Quality of Life (ACL-QOL) outcome, other clinical outcomes, and traumatic ACL reinjuries were compared at five years following the ACL reconstruction.

A total of 315 patients (95 per cent) completed their five-year followup study visit. ACL-QOL scores increased significantly from pre-surgery to five years post-surgery. The ACL-QOL scores for each group at five years were similar. Researchers found a normal to nearly normal knee function and better rotational stability trending in favour of the patellar tendon group, compared with the hamstring and double-bundle groups.

It is rare to be able to capture detailed information at five years after surgery. The worldwide gold standard is to achieve 80 per cent followup; this study has greatly surpassed that rate.

“This remarkable followup rate is a direct reflection of our research assistants and the staff at the Sport Medicine Centre. Without their support, dedication and engaging attitudes, this would not have been possible,” says Mohtadi.

The study: "A Randomized Clinical Trial Comparing Patellar Tendon, Hamstring Tendon and Double-Bundle ACL Reconstructions: Patient-Reported and Clinical Outcomes at Five-Year Follow-Up" is now published in The Journal of Bone and Joint Surgery (June 5, 2019, Volume 101, Issue 11).

A video summarizing the study is also available here


The Sport Medicine Centre in the Faculty of Kinesiology provides quality care in physiotherapy, massage therapy, athletic therapy, performance nutrition and X-ray services alongside a team of sport medicine physicians and orthopaedic surgeons. It is the hub of sport medicine research since being established at the University of Calgary during the 1988 Winter Olympic Games. It delivers integrated care to elite and recreational athletes on campus and in the community. Find out more.