If you go back 20+ years, you’ll be hard pressed to find research papers looking at non-operative management of ACL injuries. Then the 2000’s came along, and interest started to grow on the back of some promising research showing that there are some ACL injured athletes (both elite and non-elite) who were able to go back to their pre-injury levels of sport without an ACL reconstruction (ACLR) – and able to cope without their ACL for many years after returning back to sport. 

Myklebust and colleagues (2003) showed that in a group of 79 elite handball players who had injured their ACL, 22 of them attempted to return to sport back to their previous level without a reconstruction, and 82% of them did for a further 4 years of competitive sport! When the authors looked at the ACLR group, they found that only 58% of returned back to their pre-injury level of sport for a further 3.8 years of competitive play. Furthermore, 22% of the ACLR group sustained an ACL graft rupture at some point upon their return to sport. What was even more interesting was that when they looked at long term outcomes between the 2 groups (mean 7 years after their injury), there were no significant differences between the groups for pain episodes, instability, OA changes, function and quality of life.

Meanwhile, Hurd et al (2008) in the late 90s and early 2000s observed over 300 non-elite ACL injured athletes over 10 years. One of their key findings was that, after a physiotherapy assessment, 42% of this group were “potential copers” – meaning that despite not having an ACL, they were found to have a strong, stable, functional knee - and were encouraged to pursue a nonoperative pathway for as long as they liked.

And many of them did! In fact, 72% of these “potential copers” felt so good, that at some time point over the next 10 years they decided to return to their pre-injury level of sport (which included pivoting sports like basketball, soccer etc). And many of them still were left standing and coping without their ACL at least 10 years after their injury; with the 10-year follow-up results showing that 40% of the “potential copers” were still managing their everyday lives without their ACL, and the other 60% electing to have a delayed ACLR.

Man performing ACL rehabilitation exercises on a balance stool after ACL reconstruction surgery to get back to playing sports.

Then in 2010, the first and only paper of its kind (to date) was published by Frobell and colleagues that showed there were no significant differences between groups in regards to function, quality of life, physical activity levels at 2 year follow up when comparing ACL injured patients were randomly assigned to either having an ACL reconstruction or having the option for a delayed reconstruction whenever they chose (Frobell et al 2010).

The strength of this study comes from its very sound methodology (randomisation) that minimises the risks of potential biases that can creep into a study that can affect the interpretation of the results.

What was even better about this study was that the same authors then followed the same group of ACL-injured patients again at 5 years following their initial injury, and found that there were still no significant differences between either of the groups (early ACLR, delayed ACLR and rehab alone) for any outcome measure (function, quality of life, physical activity levels, OA changes, meniscus surgeries) and 50% of the delayed ACLR group (rehab alone) were still coping without their ACL!

This wonderful work by Frobell and colleagues has been a real game changer for both health professionals and their patients. The option of being able to manage an ACL injury without surgical reconstruction has no doubt been helped along by this high-quality research and by some high-profile cases of elite athletes being able to compete at the highest level without their ACL (EPL soccer athlete, various winter games athletes, rugby league athlete).

As important as this research has been for our ACL injured patients, and as exciting as it may seem that ACL injuries can be almost treated like an ankle sprain, it is really important that we also acknowledge that there were some important exclusion criteria in both the Frobell & Hurd papers – meaning that some ACL injured athletes were of a particular age, physical activity level, or had other injuries at the time of their ACL injury that saw them excluded from the study and not included in the data collection for the trial.

It is really important that we as clinicians understand this so that we can counsel our ACL injured athletes appropriately as to who may be suitable for a nonoperative rehab plan, and those that may not; because not all ACL injuries are created equal.

Female AFL athlete in pain due to ACL injury which requires ACL reconstruction surgery.

Looking at both the Frobell and Hurd studies, the first thing to understand is that the information collected was of ACL injured athletes who have injured their ACL for the very first time. Patients who had a previous ACL injury to either knee were excluded; so unfortunately, we don’t know how successful one would be if they chose a nonoperative pathway for their second (or third, or fourth) ACL injury.

Age is a very important consideration, and looking at the strongest of the studies, the Frobell study, they only looked at ACL injured patients who were aged between 18-35 years of age (mean age 26). Meaning that care needs to be taken when applying this information to younger, skeletally immature patients, and older ACL injured patients. The Hurd paper extended their data collection to ACL injured patients aged between 13 years and 57 years of age (mean age 27yrs), but one must keep in mind the methodological quality of this paper wasn’t as sound as the Frobell studies.

More often than not, other knee injuries occur at the same time of ACL injury; for example, meniscus tears, bone bruises, MCL injuries. Other types of knee injuries were a consideration in who were included in these studies and who weren’t.

In the Frobell study, they included patients who also had minor/mild meniscus tears that would not affect rehabilitation due to restricted ROM bracing, grade 1-2 injuries to MCL/LCL/PCL injuries and those knees that already had mild OA changes or mild cartilage damage. However, they did exclude patients who had complex meniscus tears that needed extensive repair and protected weightbearing for many weeks following surgery, full thickness cartilage injuries to the knee and grade 3 injuries to the MCL and LCL. The Hurd paper had similar inclusion/exclusion criteria.

Lastly, it appears from the ACL-injured patients included in these 2 studies is that care needs to be taken when interpreting the findings of these studies to professional athletes; as professional athletes were not included in the data collection.

As much as I think professional athletes should be given every opportunity to attempt nonoperative rehab; and the work from Myklebust et al 2003, and the case of the professional EPL player returning to play at 8 weeks following ACL injury and continuing to play at least 18monts later (Weiler et al, 2015) will certainly justify this; the thing to understand about professional sport is that it is a completely different beast to non-professional sport.

So many external variables weigh into the decision-making process when it comes to the paid professional athlete; age, playing position, how many years they have left in the game, time in the season, and how long into their playing contract they are. Do they have any 1-2 year goals like play in a World Cup? These are just some examples of other decisions that need to be made when dealing with a professional athlete. It is a very difficult decision to make, and I commend any athlete and medical/rehab/high performance staff for giving a nonoperative plan a red-hot go!

In summary, based on high-quality research, nonoperative management of ACL injuries is a really viable option for some ACL injured patients.

Generally speaking, patients aged over 18, even those who are participating in pivoting sports like soccer/netball/basketball, who have injured their ACL for the first time, who may also have minor injuries to other parts of the knee, can be offered nonoperative ACL management knowing that the long term outcomes (at least 5 years down the track) will be similar to those who have had an early or delayed ACL reconstruction.

At this stage however, we can’t guarantee successful short term and long term outcomes with nonoperative ACL management (as compared to ACLR) in skeletally immature athletes, professional athletes and those that have high grade injuries to other structures of the knee at the time of their ACL injury.

As always, sound clinical reasoning and shared decision-making with the patient needs to applied to each ACL case, and ACL injuries and rehabilitation options should never be managed with a “one-size-fits-all” approach.



Frobell et al (2013) – Treatment for acute anterior cruciate ligament tear: five year outcome of a randomised trial. BMJ. 2013 Jan 24;346:f232

Hurd et al (2008) - A 10-year prospective trial of a patient management algorithm and screening examination for highly active individuals with anterior cruciate ligament injury: Part 1, Am J Sports Med. 2008 Jan;36(1):40-7.

Mylebust et al (2003) - Clinical, functional, and radiologic outcome in team handball players 6 to 11 years after anterior cruciate ligament injury: a follow-up study. Am J Sports Med. 2003 Nov-Dec;31(6):981-9

Weiler et al (2015) - Non-operative management of a complete anterior cruciate ligament injury in an English Premier League football player with return to play in less than 8 weeks: applying common sense in the absence of evidence. BMJ Case Rep. 2015 Apr 26;2015