Should You Always Get ACL Surgery?

To go under the knife or to not go under the knife? That is one of the most common questions I get asked on a daily basis. Of course, no one wants to make the wrong choice!

And like most of my answers I give as a physical therapist – it depends. Maddening, I know, but hopefully this article will help you make an informed choice that is best for you.

Background on ACL injuries

More than 250,000 anterior cruciate ligament (ACL) injuries occur annually in the United States,1 with more than half of these undergoing ACL reconstruction (ACLR).2,3

Standard of practice in the United States is to recommend immediate ACLR, with a survey of the American Academy of Orthopedic Surgeons reporting 98% of surgeons recommending surgery if a patient wishes to return to sport and 79% believing ACL deficient patients are unable to return to sports without surgery.4

Figure 1. Figure from Ardern et al 2005.5
Figure 1. Figure from Ardern et al 2005.5

In contrast, research suggests there is no difference in outcomes between early and delayed ACLR6,8, but many athletes are being educated that in order to preserve knee health and joint stability and prevent further damage to the joint, surgery is highly recommended.

However, a significant number of athletes are not returning to sports, much less their pre-morbid injury level, even with ACLR, suggesting maybe surgery is not always the answer.4,7,8 Contrary to popular belief, non-operative athletes can return to sport without needing a reconstruction.

In this article, we will discuss the most recent research regarding risks of getting an ACL reconstruction and not getting a reconstruction even with an ACL injury as well as discuss the difference between copers and noncopers.

Status-post ACL reconstruction: short-term risks


So you’ve decided to go ahead and get the surgery: now what? As with any invasive procedure, the risk of infection, while low, is always present. Details regarding infection risk will likely be a discussion between you and your surgeon prior to surgery day. Some surgeons even prescribe prophylactic antibiotics in order to reduce infection risk.

Gobbi 2016 et al reports an infection rate of 0.37% after ACL reconstruction, with an onset time of infection from surgery between 7.5 and 61.7 days.9 If you have an infection, you may see a suddenly swollen and painful knee with or without incision drainage as well as increased redness and the knee being warm to the touch. You may also experience a fever.10

knee inflammed

Deep Vein Thrombosis (DVT)

A deep vein thrombosis (DVT) is a relatively rare complication after ACL reconstruction, but because of the ramifications, it is important to note. A DVT is a clot that forms within one of the deep veins, usually in the pelvis, thigh, or calf.

While there are several risk factors for development of DVT, lower extremity injury and surgery are the two most common. Symptoms include swelling, pain and tenderness in the affected area, and/or red/discolored skin, all of which are common after injury or surgery anyways, sometimes making it hard to diagnose.

This complication is compounded by the fact that most DVTs will occur 2 to 10 days after surgery. Typically, a sudden increase in swelling or pain and a sudden decrease in knee motion may be indicative of a DVT and should be treated emergently.

In order to diagnose a DVT, you will typically get an ultrasound of your affected leg. Physicians use early mobilization, compression stockings, and medications to prophylactically prevent DVTs.11 In a study conducted by Ye et al, the incidence of DVT in patients who underwent ACLR was 14%; patients at higher risk for DVT were typically female and 35 years or older.12

Decreased Knee Range of Motion and Arthrofibrosis

It is important for patients to regain their knee range of motion as soon as possible after surgery, unless there are surgical precautions that dictate they shouldn’t. It is recommended that knee ROM is regained within the first 2 weeks post-operatively ACLR.

Inability to fully achieve knee extension ROM (ability to fully straighten the knee) may result in a host of complications including patellofemoral (front of the knee) pain, especially when a patellar tendon graft is used, quadriceps strength deficits, gait abnormalities, and potentially arthrofibrosis.

girl sitting on a clinic table with brace on her knee

Arthrofibrosis is an inflammatory response that results in extreme joint stiffness and a permanent decrease in knee motion.10,13

Depending on surgeon preference, a continuous passive motion device during the early post-operative phase will be recommended; however, in a systemic review by Wright et al., they didn’t find any substantial advantage for its use.14


It is important to manage swelling (effusion) immediately post-operatively in order to help with increasing knee motion and quadriceps activation.

Cryotherapy (cold therapy) and compression via stockings, sleeves, or ice machines will assist with decreasing effusion after surgery.10

Quadriceps Activation Deficits

Loss of lower extremity strength is a common complication post-ACLR. Regaining strength is the main purpose of early rehabilitation and will be focus for the entire course of care post-ACLR.
The focus of rehab initially is regaining quadriceps activation. You should be able to see the thigh contract and the patella (knee cap) glide upward.

knee PT 3

You also should be able to complete a straight leg raise against gravity without a lag, which means you need to be able to keep your leg completely straight against gravity. Usually the ability to complete 30 straight leg raises continuously is a benchmark for discharging the brace and/or discharging crutches.10

Status-post ACL reconstruction: long-term risks

Quadriceps Strength Deficits

Decreased quadriceps strength after ACL reconstruction has been reported to be present months to years following surgery.15 Quad strength can lead to significant functional limitations, especially related to sports participation, and can ultimately lead to increased injury risk down the road.

Appropriate strength training and neuromuscular rehabilitation techniques as prescribed by your physical therapist will assist in minimizing any quad strength deficits that need to be addressed post-ACLR.10

Graft Failure

Risk of ACL graft failure post-ACLR is related to a myriad of factors, including patient age, sex, body mass index, time from surgery, graft size, meniscus integrity, tibial tunnel position, and early return to sport.16,17,18,19,20,21 ACL graft failure has been reported to be anywhere from 12 to 24%.22,23

17503027 - anterior cruciate ligament injury

Parkinson et al discovered that meniscal integrity was the best predictor of ACLR failure; increased graft laxity was found with lack of structural integrity of the medial meniscus.10,24

Risk of Reinjury

Younger age (less than 25 years old) and return to cutting/pivoting sports are correlated with an increased risk of ACL injury.25 A return to cutting/pivoting increases an athlete’s odds for an ipsilateral second ACL injury by 3.9 times and for a contralateral injury by 5 times.26

Second injuries have been reported to be as high as 24%.25 Risk of re-injury is increased in the short term if you are younger and increased ipsilaterally if you are male and contralaterally if you are female.27

Copers vs. Non-Copers: Are There Any Risks Associated with NOT Getting Your ACL Reconstructed?

ACL rupture may obviously result in increased knee joint instability and dysfunction, including inability to participate in cutting and pivoting sports. Individuals who decide to get surgery to address these deficits are called “noncopers.”

However, athletes who injure their ACL and now have an ACL-deficient knee without functional limitations or instability and successfully can return to all activities without surgery are described as “copers.”

Investigators at the University of Delaware have created an algorithm for determining a subset of patients with an ACL injury who could potentially be “copers.” See Figure 1 below for a visual representation of the selection process to differentiate between copers and noncopers.

knee soccer 2

Potential copers are individuals who met all the following criteria: (1) hop test index of 80% or more for the timed 6-meter hop test, (2) Knee Outcome Survey activities of daily living scale score of 80% or greater, (3) global rating of knee function of 60 or greater, and (4) no more than 1 episode of giving-way since the injury.

The only risk here is many athletes, especially high school ones who only have a finite amount of time left to play their sport of choice, don’t want to spend the time doing 3 months of conservative management if they’re just going to end up having surgery.

Figure 2. Algorithm for operative versus nonoperative treatment after an ACL injury from the Unversity of Delaware. Figure from Fitzgerald et al 2008.28
Figure 2. Algorithm for operative versus nonoperative treatment after an ACL injury from the Unversity of Delaware. Figure from Fitzgerald et al 2008.28

What About Osteoarthritis (OA)?!

Yes. Regardless of whether or not your get your ACL reconstructed or not, if you rupture your ACL, you are at increased risk for degenerative changes in your knee. The better your medial meniscus looks after your injury, the lower your risk of developing OA.29

The type of graft used (bone-patellar-tendon-bone or hamstring) does not seem to make a difference in laxity or graft failure, but BPTP does seem to cause an increase in anterior knee pain, pain with kneeling, and increased rates of osteoarthritis.30

knee arthrosis

At this point in time, there is no clear evidence that undergoing an ACL reconstruction is going to significantly lower your risk of osteoarthritis; it will definitely improve your knee stability but does not guarantee a future healthy knee.

With no differences in outcomes between early reconstruction, delayed reconstruction, and no surgery at all, it may be best to consider non-operative management initially as a viable evidence-based option after ACL injury. Your knees might thank you later.

infographic - acl surgery

How Adam reduced knee pain

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