Center A was a publicly funded academic clinic in Canada, which allocates healthcare resources under a government healthcare plan. Center B was a privately owned facility in the United States that primarily serves patients covered by health insurance.


Published 5/1/2008
Annie Hayashi

The ACL “window of opportunity”

Surgery within 12 weeks of injury helps reduce meniscal tears

“We found a strong association between the time from injury to surgery (TFI) of the anterior cruciate ligament (ACL) and the incidence, complexity, and reparability of meniscus tears,” said Kevin Willits, MD, of London, Ontario, Canada. “Based on the results of our study, ACL reconstruction should optimally be performed within 12 weeks of the injury to minimize the risk of irreparable meniscus pathology and to improve patient prognosis.”

Dr. Willits presented his findings at the 75th Annual Meeting of the American Academy of Orthopaedic Surgeons in San Francisco.

Healthcare systems impact surgical wait times
This 2-year, international retrospective study was conducted at two sports medicine facilities with similar patient demographics and practices but with different healthcare systems.

Kevin Willits, MD

The study included 317 patients with a well-established date of injury—156 at center A (89 males, 67 females; median age at injury: 22.8 years) and 161 at center B (85 males, 76 females; median age at injury: 21.9 years).

Patients with a combined ACL/medial collateral ligament (MCL) tear were included in the study as long as the MCL tear was a grade two or less. Those with multi-ligament injury, incomplete records, or a prior surgical procedure were excluded.

Patients at center A waited a median of 39.9 weeks for surgery, while the median TFI at center B was just 4.4 weeks. The wide variance in TFI between centers A and B can be largely attributed to the difference in healthcare systems between Canada and the United States.

Nearly 9 out of 10 patients at center A waited longer than 12 weeks for surgery; nearly three out of four waited longer than 6 months. At center B, only 15 percent of patients waited longer than 12 weeks, and only one in nine waited more than 6 months.

Patients underwent arthroscopic ACL reconstruction using a hamstrings or quad tendon autograft.

Center A was a publicly funded academic clinic in Canada, which allocates healthcare resources under a government healthcare plan. Center B was a privately owned facility in the United States that primarily serves patients covered by health insurance.
Subtotal meniscectomy performed as a result of unrepairable meniscal tear.
Courtesy of Kevin Willits, MD
Unrepairable meniscal tear seen at the time of ACL reconstruction 28 weeks postinjury.
Courtesy of Kevin Willits, MD

TFI impacts reparability of meniscal tears
“We found that patients at center B were nearly twice as likely to have reparable meniscus pathology as those at center A,” said Dr. Willits.

Of all patients in the study, 236 (74 percent) had at least one meniscal tear when ACL reconstruction was performed. Tear types included longitudinal split (46 percent), complex/degenerative (20 percent), and displaced bucket handle (15 percent).

Dr. Willits and his team “noticed a progressive increase in the incidence and complexity of meniscal tears as TFI became greater.” In fact, the incidence of bucket handle tears increased from 14 percent (TFI of 6 to 26 weeks) to 20 percent (TFI greater than 26 weeks).

Patients with a TFI greater than 26 weeks had 11 percent more complex/degenerative tears than those with a TFI of 6 to 26 weeks. These types of tears are generally more difficult to repair as they often occur in an avascular region of the menisci.

If ACL reconstruction was performed within 26 weeks of the injury, the patient was 2.3 times more likely to have reparable medial meniscus pathology. Surgery done within 12 weeks increased reparability to 3.5 times. Lateral meniscus tears followed this same trend.

Twelve weeks is optimal
“The timing of the surgery is critical,” said Dr. Willits. “Our study demonstrated that 12 weeks is the optimal time for ACL reconstruction and the most important predictor of whether the meniscus is going to be repairable or not.

“If you rush into surgery too quickly, before patients get their motion back in the knee and swelling is reduced, a stiff knee may result,” he cautioned. Lateral tears were also found more often in patients who had ACL reconstruction within 6 weeks of injury.

Based on the findings of his study, Dr. Willits outlined the “optimal” conditions for ACL reconstruction. “After a full evaluation by an orthopaedic surgeon and a diagnosis is made, the patient is sent to rehabilitation to reduce swelling and restore motion in the knee. The ACL reconstruction would be performed at or about 12 weeks—before the patient has an opportunity to return to sport or to further damage the knee prior to surgical stabilization. That is the ‘window of opportunity’ for ACL repair.”

Co-authors for “The effect of surgical timing on the incidence of repairable meniscus pathology during anterior cruciate ligament reconstruction” are Jay Akindolire, MSc; Robert Shelton, MD; Alexandra Kirkley, MD; Robert Giffin, MD; Robert B. Litchfield, MD, and Peter J. Fowler, MD. Disclosure information on the presenters can be found online at

Annie Hayashi is the senior science writer for AAOS Now. She can be reached at