How long is recovery time from an ACL tear?

Oct. 14, 2021
Soocer play grabs his knee after an ACL tear which will be an 8-9 month recovery time.
An ACL tear recovery time is generally eight to nine months, though some people may recover in six months. Photo: Getty Images.

By Rick Ansorge, for UCHealth

In the not-so-distant past, a torn anterior cruciate ligament (ACL) commonly killed the careers of countless amateur and professional athletes.

Thanks to recent advances in the diagnosis, treatment and management of ACL injuries, most athletes now can return to their previous level of functioning.

The ACL is one of two ligaments that cross in the middle of the knee. It connects the thighbone to the shinbone and stabilizes the knee joint by preventing forward-and-backward motion.

“The ACL is a big deal to anybody that’s active and likes to participate in athletics, particularly in Colorado where so many people love downhill skiing,” said Dr. Eric McCarty, a UCHealth orthopedic surgeon at the CU Sports Medicine and Performance Center in Boulder who also practices at UCHealth Steadman Hawkins Clinic – Denver.

Although the ACL is strong, it’s vulnerable to sprains, partial tears, and complete tears. In the United States alone, an estimated 100,000-200,000 ACL tears occur each year.

What causes ACL injuries?

ACL injuries commonly occur during “twisting and turning” sports that involve sudden stops or changes in direction, jumping and landing, McCarty explained.

Such activities include non-contact sports such as downhill skiing, gymnastics, and tennis, and contact sports such as football, soccer, basketball, and rugby.

Dr. Eric McCarty, UCHealth orthopedic surgeon at the CU Sports Medicine and Performance Center in Boulder who also practices at UCHealth Steadman Hawkins Clinic - Denver, talks about ACL tears and recovery time.
Dr. Eric McCarty discusses ACL tears and recovery time.

“You may think of a bad knee injury as resulting from somebody running into or banging into you” as happens during a football tackle,” McCarty said. “But most ACL injuries are non-contact injuries.”

Non-contact ACL injuries usually occur when an athlete makes a cut or pivot that forces the knee to rotate or bend sideways.

For reasons that are unclear, female athletes are four times as likely as their male counterparts to experience an ACL injury. “We see a lot of tears in adult and youth soccer, particularly in the female athletes,” McCarty said.

Contact-related ACL injuries usually occur when a direct blow forces an athlete’s knee inwards toward the other leg. In football, this often happens when a player’s foot is planted and an opponent runs into the outside or front of his thigh.

About 50% of the time, an ACL tear is accompanied by other knee damage, including injuries to the other ligaments and one or both of the menisci (the cushions in the knee that help to protect the cartilage).

Who is at risk of ACL injuries?

In addition to participation in twisting and turning sports – and being female – factors associated with an increased risk include:

  • Poor physical condition.
  • Using improper mechanics, such as moving the knees inward during a squat.
  • Wearing ill-fitted footwear.
  • Using poorly adjusted sports equipment, such as skis with bindings that won’t release during a fall.
  • Playing on artificial turf.

 What are the symptoms of an ACL injury?

The “classic” first symptom is a loud pop or popping sensation in the knee, McCarty said.

Soon after an ACL tear, most people also experience severe pain and a feeling that the knee is unstable or “giving out.” Within a few hours, almost everyone develops swelling in the knee caused by bleeding from injured blood vessels.

Immediate first-aid care can reduce pain and swelling after a knee injury. McCarty recommends the R.I.C.E. model of self-care at home:

  • General rest is necessary for healing and limits weight bearing on your knee.
  • When you’re awake, try to ice your knee at least every two hours for 20 minutes at a time.
  • Wrap an elastic bandage or compression wrap around your knee.
  • Lie down with your knee propped up on pillows.

“If you have any type of injury where you feel a pop and/or swelling, it’s important to get a medical diagnosis as soon as possible,” McCarty said. “It’s essential to understand the extent of the injury so you can receive appropriate treatment.”

How are ACL injuries treated?

The two main options are either surgery and post-surgical rehabilitation or a non-surgical rehabilitation program.

Since the early 1980s, surgeons have reconstructed torn ACLs by replacing them with autografts, tendons that have been harvested from elsewhere in the patient’s body. These include the patellar tendon from the front of the knee and tendons from the quadriceps and hamstrings.

In some cases – usually in older adults who are still physically active – surgeons use allografts, tendons that come from deceased persons who have donated their bodies to science. Because allografts are associated with higher rates of re-tearing than autografts, they’re seldom used in athletes under age 40.

ACL reconstruction is a serious but minimally invasive surgery. After making small incisions in your knee, the surgeon uses a wand-like device called an arthroscope to remove the torn ACL and replace it with a graft.

In the weeks preceding surgery, patients should be placed on a “pre-hab” program that gently exercises and strengthens the knee. Post-surgical rehab programs are rigorous regimens that require daily exercise and can last for months. For optimal results, total adherence to the program is required.

Deciding whether or not to have surgery involves many factors. Your doctor may advise you to forgo surgery and complete a non-surgical rehabilitation program to strengthen and stabilize the knee if you:

  • Have a partial ACL tear that may heal with rest and rehabilitation.
  • Do not participate in twisting and turning sports (especially if you’re age 55 or older).
  • Are willing to give up pivoting sports such as skiing in favor of non-pivoting activities such as running and bicycling.

“You don’t need an ACL to run or ride a bike,” McCarty said.

In rare instances, athletes can continue to participate in pivoting sports without an ACL because they have exceptional muscle strength and control, McCarty said. “But I would say that most athletes cannot.”

How has the treatment advanced to improve ACL tear recovery time?

“The surgery has come a long way since the early 1980s,” McCarty said.

Since it’s become a minimally invasive procedure, it’s now routinely performed on an outpatient basis. Patients who used to be immobilized in a cast or splint for a week after surgery are now started on physical therapy the day after surgery.

“We’re getting them moving. We’re getting the muscles going,” McCarty said. “I think that’s important.”

Technological advances are also helping speed the recovery time after an ACL tear.

These include the continuous passive motion (CPM) machine, which can be prescribed by a doctor for at-home use. The CPM machine moves the knee through a range of motion and helps prevent the formation of scar tissue. McCarty and his colleagues, however, have found that good physical therapy is just as effective good as using this device.

Some doctors may also prescribe devices that decrease pain and inflammation after surgery by cooling or compressing the knee. One such device – the cold compression machine – does both at the same time. It uses an inflatable sleeve that wraps around the knee to circulate cold water and provide compression.

The combination of cold and compression is more effective at relieving pain and swelling than what for decades was a mainstay treatment. “It’s better than a bag of ice,” McCarty said.

How long does it take to recover from ACL surgery and return to sports?

“It takes a while for the graft to become part of the body and go through a process of we call ligamentization, which is becoming a new ligament,” McCarty said. “That process can take nine or 10 months.”

Although some exceptional athletes can return to sports in six months, a more realistic scenario after an ACL tear is a recovery time of at least eight to nine months.

“Even then, after you’ve done great therapy and have come back to sports, it can sometimes take another year before you feel normal again,” McCarty said.

His patients often tell him that it isn’t until the second season after ACL surgery that they feel like they have fully returned to their previous level of play.

Since everyone heals differently, there’s no set time for athletes to return to sports. Tests can determine whether or not a reconstructed knee is as functional as the other knee and up to the rigors of a particular sport. Doctors and physical therapists usually have the final say on whether or not an athlete is ready to compete safely.

Research shows that up to one-third of athletes sustain another ACL tear in the same or opposite knee within two years, suggesting that an ACL tear recovery time of 10 months or longer may be associated with a lower risk of re-injury.

Can ACL injuries be prevented?

Although there’s no guaranteed way to prevent an ACL tear, the American Academy of Orthopaedic Surgeons and the American College of Sports Medicine have endorsed training programs to help reduce the risk.

Experts recommend such programs for any athlete who is at high risk of an ACL injury, such as football players and skiers.

The goal of such programs is to:

  • Strengthen muscles of the legs, hips and core.
  • Improve jumping and landing techniques to prevent inward movement of the knee.

Research shows that reduced injury rates are associated with a comprehensive training program that includes strength training, balance training, and individualized instruction about proper positioning and movement. Such programs may be especially useful for reducing ACL injuries in female athletes.

Strength or balance training alone is unlikely to have any beneficial effect.

Ideally, athletes should participate in prevention training at least twice per week for a minimum of six weeks before the start of their season.

“If you’re a skier, don’t wait until December to start a skiing conditioning class and don’t try to condition on the slopes,” McCarty said.

You may be in great physical shape from summer hiking, running, and bicycling. “But these are different sports than skiing,” McCarty said. “You need to have the appropriate neuromuscular control, strength, endurance, and flexibility in order to ski safely.”

Prevention programs are usually geared to a particular sport. Athletes who play soccer, basketball, or volleyball, for example, are taught to be mindful of how they take hard, quick steps to accelerate in another direction (or “cut”) and they land on their feet from a jump or a step (“plant”).

Improper cutting and planting are responsible for about 70% of all ACL injuries.

Initially, a prevention program should be taught and supervised by a sports medicine physician, athletic trainer, or physical therapist who can tailor it to your needs.

“Some of the basic principles are similar for every sport,” McCarty said. “But the pivoting you do on the court is different than the twisting that happens when you get off balance on a ski. So the instruction needs to be individualized.”

What’s on the horizon for ACL treatment?

According to McCarty, the most exciting new development is bridge-enhanced anterior cruciate ligament restoration, also known as the BEAR implant.

Unlike ACL reconstruction – which relies on a graft from the patient or donor – BEAR can heal a torn ligament. The procedure uses a an implant containing bovine collagen and the patient’s own blood to fill the gap between the torn ends of the ACL and promote healing.

“Traditionally, the ACL does not heal itself,” McCarty said. “There are a lot of factors that don’t allow for it.”

These include impaired blood flow to the ligament after an injury and cells inside the synovial fluid in the knee that prevents healing.

Previous attempts to heal an ACL tear have all ended in failure. “Now there’s the potential that you can heal your own body,” McCarty said.

Pioneered by Dr. Martha Murray, orthopedic surgeon-in-chief at Boston Children’s Hospital, the BEAR procedure has shown such promising early results that the FDA authorized its marketing in late 2020.

BEAR is now being studied at sites across the nation, including UCHealth. Select patients will be randomized to receive either BEAR or traditional ACL reconstruction without knowing which surgery was performed.

If BEAR proves to be comparable or superior to grafts, it could become the new gold standard for ACL treatment. But that will require years of study and analysis.

“So that is really new and innovative,” said McCarty, who has been trained in the BEAR procedure but has not yet performed it.

Another promising approach is stem-cell injection therapy, which has been tried by some doctors but so far has yielded mixed results. “Maybe there’s some potential for it in the future,” McCarty said. “But it hasn’t been studied well enough, so I would approach it with caution. We’re still learning how to harness the power of stem cells.”

Probably the most futuristic approach would involve generating an entirely new ACL in the lab for transplant into the patient. “We may be able to biogenetically grow something that would be just as good as your own tissue, but we’re not there yet,” McCarty said.

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