When to Return Your Athletes with ACL Reconstruction to Play

In my 2016 article, “When to Return to Sport? A Brief History of ACL Rehabilitation Approaches,” I presented my concerns that our current return-to-play protocols following ACL reconstruction were flawed and not nearly as predictable as perceived.

Unfortunately, between that time and now, we have only seen increasing evidence of this issue, and we now appreciate a significant problem: Our ability to appropriately direct and advise an athlete in return-to-play decisions after ACL reconstruction is not adequate. This creates a true crisis for any athletic trainer working with an athlete who is adamant that they are ready.

A Brief History of the Literature: The ‘80s and ‘90s

In that original article, I referenced the 1981 work of Paulos, et al., which included the quote, “The classic parameters of return to play do not indicate healing of ligament tissue and must not be substituted for time restraints.”¹

In 1990, Shelbourne and Nitz published their study in which they followed non-compliant individuals to be certain their accelerated approach had not led to early failure or poor long-term outcomes. They concluded, “Furthermore, comparative data from the two groups in this study population demonstrate that range of motion, strength, and function can be achieved by an accelerated rehabilitation regimen without compromising stability or putting the graft at risk.”²

In June of 1992, the Journal of Orthopaedic and Sports Physical Therapy dedicated their pages to the care of those who had an injured ACL, with several MD/PT teams presenting their approaches to ACL post-operative management within the context/comparison of the Shelbourne and Nitz protocol. We provided a historical comparison to extra-articular surgery and noted how many of the “accelerated concepts” were reflective of the management applied in these cases.³

Unfortunately, even though many of the published surgeons and therapists urged caution, the next several years devolved into a scenario of “the sooner the better” for return to play. If other practitioners promised a nine-month return to play, then six months was seen as better. Soon, there were no longer any time frames—the practitioner who promised the earliest return to activity was seen as the best.

The Literature from 2000 Onward

In the 2000 text Knee Ligament Rehabilitation, edited by Todd Ellenbecker, the neuromuscular concepts chapter presents a lengthy discussion related to the short- and long-term implications of ACL ligament reconstruction.⁴ The authors cite Levine, et al., who demonstrated that neurogenic inflammation is impactful for several months.⁵ The chapter authors proposed “that some of the challenges seen in the first weeks and months following significant insult (injury or surgery) are related to this neurally mediated process.”

Over the past 15 years, greater attention to surgical technique and outcome scrutiny have begun to swing the pendulum away from the mantra of “get them back as soon as possible.” A 2015 study conducted by Kim, et al., made surgeons carefully consider the orientation and impact of anatomy and attempts at better restoring such during reconstruction.⁶ In another study, several of these same researchers outlined the loading seen in grafts after implementation and, thus, during rehabilitation.⁷ This work points toward greater direct loading to the graft when it is placed anatomically, thus asking clinicians to consider if early rehabilitation may need to be less intense and less likely to improperly allow excessive loading.

Two additional articles bring into focus the concern of second ACL injury upon return to play. The MOON Consortium has provided significant data to recommend specifics on graft use as well as guidelines for rehabilitation.^{8, 9} Paterno, et al., followed a mixed cohort on return to play and provided quite concerning data showing that young females have about a 25 percent chance of sustaining a second ACL injury within the first year after returning to full participation.¹⁰

Challenging the Status Quo

Since that original article, several other intriguing studies have really challenged the status quo. Grindem, et al., directly state that applying basic decision rules will reduce re-injury risk by greater than 80 percent.¹¹ Most frightening to athletic trainers: They espoused that returning to level 1 sports leads to a fourfold increase in re-injury over a two-year window.

After examining biologic and functional data, Nagelli and Hewett wish us to consider a two-year wait on return to play following surgery.¹² And in 2019, Kaplan and Witvrouw completed a systemic analysis of the literature related to safe return to sport following ACL reconstruction. Their conclusion was that as a result of high re-rupture rates (especially in young athletes), a delayed return to play of nine or more months is supported.¹³

This information requires us to question how to best inform our athletes. We must also recognize that those returning early are at greatest risk. Balancing that risk and making the best recommendations is incredibly difficult.

Informing Your Athletes

So as an AT working in the high school or intercollegiate setting—what should your message be to your athletes following ACL reconstruction?

Ardern, et al., provided a 2016 consensus statement on return to sport following injury. This document was generated through a 17-clinician panel that examined the issue from multiple perspectives, concluding that the decision should be an ongoing process throughout rehabilitation and not just a checkbox at the end of formal rehabilitation.¹⁴ Biopsychosocial factors and an assessment of risk and risk tolerance specific to the individual should be part of this process.

Importantly, research evidence to support return-to-sport decisions is scarce and not definitive. In a later article, Ardern, et al., established a series of queries to address when considering return-to-play decisions. These include:

• How do you determine readiness for return?
• Is physical recovery alone enough for return to play?
• What is successful return to play?
• What are the clinician’s responsibilities within the sports medicine team to the athlete?
• Should the athlete return to play?¹⁵

Werner, et al., and Burland, et al., documented that physical performance alone may not be an ideal outcome measure and that psychosocial factors are of great significance in return to sport after ACL reconstruction.^{16, 17}

These recent references all point to using an integrative model and recommend consideration of risk, with one example being the Shrier Strategic Assessment of Risk Tolerance. This assessment includes a stepwise approach to assessing risks, starting with:

• Health risk, including age and symptoms
• Activity risk, including sport, position played, competition level, and patient-reported outcomes
• Risk tolerance, including seasonal relationships, desire to compete, external pressures, and fear with litigation¹⁸

Making Return-to-Play Decisions

The reality is that these return-to-play decisions must be made by the sports medicine team in concert with the best management for the individual athlete. And these decisions become more complex every day as data continues to emerge. For instance, one obvious issue is that data continues to point to a minimum of nine months being required for optimal return to play after ACL reconstruction. As this number becomes more accepted, it will be more difficult for earlier return to play without significant discussions with the athlete and school officials.

ATs who work in schools may consider establishing protocols that clearly delineate nine months as the return expectation and have the team physician as well as school legal review these protocols before acceptance and implementation.

If an earlier return is considered, what are some factors you can use in the scholastic or collegiate setting? Kline, et al., demonstrated that performance of an 8-inch single-leg step down and 90-degree isometric quadriceps values were significantly correlated as clinical predictors for return to sport.¹⁹ They showed that performance at three months was predictive of six months, making it valuable as an early predictor. An important note is that those who fail to meet expected performance values of 90 percent at six months often continue to experience significant deficits for the next 18 months.²⁰ Curran, et al., show that although improved at 12 months, significant asymmetries were the rule, begging the question of the often-espoused six-month return-to-play criteria.²¹

In the previous article, I concluded by quoting songwriter Paul Simon: “Slow down—you move too fast.” This remains excellent advice for athletic trainers when considering whether or not to return their athletes to play following ACL reconstruction.