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ACL Surgery – No Longer Kneeded?

10 min read. Posted in Knee
Written by Dr Kieran Richardson info

What evidence is there to inform our decision on whether patients should undergo surgical or non-surgical management after an ACL tear?

The best way for clinician-readers to answer a specific question like this is through systematic reviews and meta-analyses, where the highest standard of empirical evidence of the effects of interventions is assessed (Travers et al 2019). Recent literature reviews have found similar outcomes in both non-surgical and surgical groups with respect to pain, symptoms, function, return to sport levels, quality of life, subsequent meniscal tear and surgery rates, and radiographic knee osteoarthritis (OA) prevalence (Smith et al 2014, Delincé and Ghafil 2012, Monk et al 2016).

We know randomised control trials (RCT’s) are the optimum study design for musculoskeletal pain and injury presentations when examining the effectiveness of exercise therapy to non-necessary-for-life surgical procedures. Ideally, when testing interventions, a placebo surgery arm should also be utilised, with common elective operations for knee, shoulder and elbow now being shown to be no better than placebo (Sihvonen et al 2013, Beard et al. 2018, Kroslak and Murrell 2018). This is yet to be undertaken in ACL injury, therefore clinicians are being challenged to be sceptical, think critically and scrutinise the necessity of any optional surgery yet to be tested in a placebo-controlled trial (Zadro et al 2019).

It is almost unfathomable that a recent review by Kay et al 2017 revealed that only 1 of 412 ACL randomised controlled trials actually compared ACL reconstruction (ACLR) to structured rehabilitation for acute ACL injury, with essentially all other studies comparing various ACL surgeries and graft types to one another (Culvenor and Barton 2018). This single RCT, the famous KANON (Knee Anterior Cruciate Ligament, Nonsurgical versus Surgical Treatment) trial by Frobell and colleagues (2013), recommended that their “results should encourage clinicians and young active adult patients to consider rehabilitation as a primary treatment option after an acute ACL tear.” Given cultural trends in Western society to this point in history – this really is liberating, hopeful and revolutionary thinking!



Why do you think so many physiotherapists and athletes believe surgery is needed after an ACL rupture?

This is a great question that has many facets to cover, and one that could almost be its own PhD research investigation! For me three critical drivers of this ideology are beliefs around the ligament itself, our current healthcare models and the mainstream media.

Our understanding of ACL tears has shifted from one of ‘the ACL’s job anatomically is to do X, Y and Z so let’s try to replicate that surgically’, to one of ‘what do the best-designed studies show that compare the 2 groups of attempting to reconstruct the ligament and receiving rehabilitation, versus undertaking physiotherapy and exercise alone?’ So in our efforts to ‘re-create’ a ligament an entire world-wide, multi-billion dollar per annum industry has burgeoned, and the studies of the best methodological rigour are challenging what we used to believe.

We previously theorised that ACLR prevented OA and further meniscal damage compared to individualised, graded functional strengthening alone; we now realise this is a misconception not supported by high-quality science, with suggestions now ACLR could in fact increase the risk of OA

(Nordenvall et al 2014, Culvenor et al 2019, Filbay 2019). Studies are also now showing, if left, the ACL can heal (Ihara et al 1994, Fujimoto et al 2002, Costa-Paz et al 2012) despite previous belief this was impossible through a lack of blood clot formation.

In Australia at least, where we have the highest rates of reconstruction in the world (Zbrojkiewicz, Vertullo and Grayson 2018), all of our public and private healthcare models are set up to speed-up and fund early MRI, early surgical opinion and early surgery. Physiotherapy and exercise as ‘treatment and management’ of ACL tears is currently not routinely advertised, funded or recommended through government systems or private insurance companies, so both clinicians and patients are simply unaware of the quality of the research for the intervention they may receive.

There is a pervading view in mass media of alarmism and devastation when a player injures their knee on the pitch, with commentators often ‘fearing’ the worst. The emotion follows as the assumption is the athlete has injured their ACL and will require surgery and will need 9 to 12 months off their sport – this is a false narrative which we need to replace with a rational explanation of the most substantive data, and encourage players (and the general population) that many can function at the elite level without the need for invasive surgery.


What does the research suggest is the best management plan after an ACL rupture?

Given the lack of high-quality studies showing additional benefit of reconstruction to physiotherapy and exercises, authors are now highlighting the “emerging realisation that athletes may be overtreated with ACLR surgery, but undertreated when it comes to rehabilitation” (Grindem, Arundale and Ardern 2018) therefore a cultural shift away from early surgery and towards non-surgical management, with surgery “as needed” is required (Zadro and Pappas 2018).

Further analysis by Filbay et al (2017) of the KANON trial showed patients who received early ACLR were prognostically worse across multiple domains compared to the non-surgical and delayed surgical arms, suffering a ‘second trauma’ due to the surgical drilling through intra-articular structures, a period of prolonged joint inflammation and altered weight bearing (Bowes et al 2019, Larsson et al 2017).

We need to take our time educating any patient after an ACL injury about the said evidence through a shared-decision making process, underscoring to them the concept of commitment and adherence to graded, comprehensive, longstanding rehabilitation, with prevention exercises maintained after return to sport. We need to confront any belief that an ACLR is a ‘quick fix’ (Zadro and Pappas 2018), stress the many benefits of undertaking immediate rehabilitation alone ideally for at least 3 to 6 months, which is termed ‘World’s Best Practice’ (Rooney 2018). The bottom line is for many active patients, non-surgical management continues as a permanent, life-long solution.


What should the rehab process look like for someone undergoing non-surgical management? Similar to rehab post ACL reconstruction?

The rehabilitation process really is very similar, however timeframes are expected to be decidedly faster, given there is no need to recover from surgery, or a graft to monitor. Static, non-weight bearing tests for stability like pivot-shift or Lachman’s are less relevant, as it is now well-known that there is a poor correlation between them and functional stability (Snyder-Mackler et al 1997, Hurd et al 2009).

I like to use questionnaires such as the IKDC and KOOS (Collins et al 2011, van Meer 2013) for baseline assessment of patients’ knee function, and the short form of the Örebro Musculoskeletal Pain Screening Questionnaire (Linton et al 2011) to screen for psychological risk or the Tampa Scale of Kinesiophobia (Miller et al 1991) to analyse for the presence of fear-avoidance.

It important to outline to the patient the expected stages of the program and criteria for progression, ideally in a verbal and written Treatment Plan. Management initially involves reducing pain and effusion, while improving ROM, muscle strength, function and movement patterns.

End stage physiotherapy to return to sport includes sports performance (e.g. acceleration, agility, coordination, balance, endurance and sport-specific skills) and assessment of psychological readiness (Filbay and Grindem 2019). Post successful return to play, ‘booster’ follow-up sessions can be scheduled periodically to ensure continued compliance with preventative exercises (Skou et al 2018, Fleig et al 2013, Nessler et al 2017). I also encourage patients to share their success stories with friends, family, colleagues and social media connections, so the general population can benefit from these positive messages!


Can you return to pivoting sports without surgery? Any good case studies in elite athletes?

Absolutely. It’s important for readers to know that it is a fallacy based on biologically-plausible theory that you cannot return to pivoting/cutting sports with an ACL-deficient knee – there are plenty of peer-reviewed papers that show returning to these types of sports is achievable and safe for many patients (Meuffels et al 2009, Grindem et al 2012, Kovalak et al 2018). There is in fact not a single study, at a group level, that shows you can’t return to twisting sports without an ACL. Through intense strengthening, neuromuscular control, balance and sports specific training your musculoskeletal system can be more than adequate to compensate for ligament laxity, making the ligament essentially redundant.

Studies in professional athletes which compare physiotherapy alone to surgery plus physio haven’t actually shown any benefit to the surgery group. A prospective study from Sweden in the 90’s showed no signi?cant difference in return to sports rates and OA in professional soccer players (Roos et al. 1995), as did a group-comparison study by Myklebust in 2003 in professional European handballs players. Van Yperen et al. (2018) compared 50 high-level athletes and found no between-group differences in meniscectomy rates, radiographic OA, and functional outcomes at 20-year follow-up.

The most famous non-operative case study was in an English Premier League player who returned to play without surgery in 8 weeks following a full thickness tear and remained problem-free long-term (Weiler et al 2015, Weiler 2016). There are many others who have been champions at the elite-level in various sports, including in the NBA, NFL and Major league Baseball, although DeJuan Blair is one of my personal favourites: successfully playing in the NBA for the San Antonio Spurs for multiple seasons without an ACL in either of his knees!


What are some key variables that might help us predict whether someone is likely to be a ‘coper’ or ‘non-coper’ from non-surgical management?

The jury is out on how to predict whether someone ‘needs’ an elective reconstruction – we don’t know whether it is cultural tendencies, typical healthcare pathways, beliefs/fear/preferences of the clinician or patient/parents/sporting clubs, lack of commitment to the rehab or true pathophysiological reasons of their knee giving-way with resultant persistent pain and effusion despite high-quality, intense, structured and graded rehabilitation.

Traditional algorithms have been heavily biased towards early ACLR, with elements such as progressive, intense rehabilitation beyond a rigid time frame, movement patterns and psychological fear-avoidance never previously considered ((Fitzgerald, Axe, Snyder-Mackler 2000, Hartigan et al 2013). Many patients that have been classified as ‘copers’ still decide to opt for surgery (Hurd et al 2008), and many ‘non-copers’ if given adequate time ultimately become ‘copers’! (Thoma et al 2019, Moksnes et al 2008).

Based on the KANON trial, psychological factors such as pre-existing preferences, beliefs and lack of motivation towards rehabilitation and exercises were the main reasons patients chose to have a reconstruction (Thorstensson et al 2009), with physical performance of quadriceps strength and hop tests key factors of success (Ericcson et al 2013) in all groups. Choosing to not have an ACLR and opting for exercise therapy alone is also a prognostic factor for less knee symptoms at 5-year follow-up (Filbay et al 2017).


How do you address potential psychological impairments following ACL rupture for those following a non-surgical pathway?

Again, this is such an excellent question with a myriad of potential topics to cover! In our subjective examination we need to at least in a cursory way question around patient beliefs of the injury management options, their expectations, short and long-term goals, social considerations, fears and motivations (Burland et al 2019, Sommerfeldt et al 2018, Scott, Perry and Sole 2017). I have writings elsewhere that speak to specific screening questioning around these elements (Richardson 2018).

In the physical examination, I observe for manifestation of fear-avoidant movement patterns through the affected limb: guarding, bracing, excessive co-contraction of the hamstrings and quadriceps and disproportionate off-loading of the knee (Hartigan et al 2013). I then attempt to correct this with verbal or tactile cues and reassurance to change these aberrant motor-control strategies, which hopefully in turn increases the quality and range of motion (ROM) during functional task assessment and reduces pain.

Want to become more confident treating ACL tears non-surgically?

Dr Kieran Richardson has done a Masterclass lecture series for us on:

“Non-surgical Management of ACL Tears”

You can try Masterclass for FREE now with our 7-day trial!

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Leave a comment (4)

If you have a question, suggestion or a link to some related research, share below!

  • Renny Rengganis

    I experienced a Grade 3 ACL 2 weeks ago, 31 December 2022. I would opt for a conservative treatment rather than surgery. Can a full ACL tear healed without surgery? I would rather opt for life time exercise commitment rather than having a surgery.

    Renny Rengganis | 14 January 2023 | Likes
  • Francisco Merino

    Coming from personal experience. I opted to rehab for 8 months without surgery. I then came back to competitive soccer and lasted 25 minutes before I completely tore what I had left of my ACL. I’m not pro surgery and as a PT conservative care is a must; however, we can’t just overlook the importance of an intact ACL on knee stability.

    Francisco Merino | 30 June 2020 | Likes
    • Myles Burfield

      @franciscomerino Interesting comment Francisco. A big part of what the research shows is that we need no appreciate the importance of mechanical stability vs functional stability. Logic dictates that we want a mechanically stable knee, but the research and especially longitudinal studies >10years are showing that functional stability is adequate to maintain knee health, and may be more important that mechanical instability in the absence of functional stability. It’s no longer accurate to say “we need an ACL to stabilise the knee”

      Myles Burfield | 28 June 2021 | Likes
  • Dion David

    very informative. problem is changing the mindset from surgical intervention to conservative intervention.

    Dion David | 04 November 2019 | Likes

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