Not ready to return to sport after ACLR? Bring a friend!

Anterior cruciate ligament (ACL) tears are the bread and butter for many an outpatient orthopedic practice. Still, physios the world over would happily go into semi-retirement if they could improve the outcomes of ACL repairs (ACLRs). As it stands today, just over half of the 250,000 to 300,000, who suffer an ACL injury in the United States achieve their pre-injury status and return to play(1). Less than half of those injured return to competitive play. That means around 60% don’t fully actualize their desire to compete(1). Those that do return have an increased chance of re-injury.

The low rate of return to competition and frequency of re-injury likely indicate a failure in the rehabilitation system. One reason for these statistics may be the lack of psychological readiness training. As Tracy Ward explains, the psychological component of readiness likely influences the return to play more than clinicians realize. Alicia Filley further suggests that factors beyond strength and range of motion, such as the connectedness an athlete feels with their therapist, impact return to play status.

To address some of these issues, researchers in Bloomington, Minnesota, developed an advanced group training program for those at least five months post-ACLR(1). Other criteria for inclusion in the program included:

  • Minimal complaints of pain
  • Minimal to no swelling in the knee
  • Full range of motion in the knee
  • Ability to safely execute a drop jump
  • Limb asymmetry of not more than 25% in the hop test

In other words, these candidates met typical discharge physiological benchmarks from their post-operative rehabilitation.

The researchers excluded an athlete if they met one of the following metrics:

  • Experienced a previous ACL injury
  • Required multi-ligament repair
  • Suffered a concurrent meniscus injury
  • Underwent ACLR more than one year prior

The study enrolled 58 athletes (who met the above criteria) into a group-training program that included plyometrics, core, and lower leg strengthening activities, along with agility drills. The athletes participated in the group setting twice per week for five weeks. Before and after the group intervention, the subjects were tested using the Anterior Cruciate Ligament-Return to Sport Index (ACL-RSI) to measure psychological readiness, and the single-leg hop test for single-hop distance, triple hop distance, crossover hop distance, and the 6-m timed hop on each leg to measure symmetry between the abilities of each leg.

The group of participants showed significant improvement in both measures of return-to-play readiness after completing the training program. However, the relationship between psychological readiness and the change in limb symmetry scores was not significant. The ACL-RSI test provides a range of scores between which athletes are ready to return to play. Using either the upper or lower ends of this range, over one-third of the athletes showed an improvement in psychological readiness post-intervention. Roughly the same number of subjects showed physiological improvement to a ready to play status after the group training. Using the lower end of the ACL-RSI range threshold, the percentage of athletes showing readiness to return to sport in both measures increased from 6.9% pre-intervention test to 53.4% post-test.

Ready to go?

While this improvement is significant, it means that nearly half of the population studied still lacked some aspect of readiness to return to sport. The group program showed the most considerable improvement in measures of psychological readiness without addressing any psychological issues, such as fear of re-injury. Perhaps those who show deficits after a group-training program would benefit from continued individual intervention to address both the mental and functional insufficiencies.

The authors acknowledge the limitations of this study, namely, the lack of a control group. Without controls, it is impossible to know if the improvements shown were merely a result of the passage of time. Also, selection bias occurred as the athletes themselves chose to participate in the program. This population was also a subset of athletes who desired to return to a prior level of competition. Furthermore, the study lacked standardized measures of lower limb strength, focusing solely on the functional hop test to measure limb symmetry but not absolute strength.

Rehabilitation professionals continue to seek ways to improve the outcomes for those who suffer an ACL tear. One novel way proposed here is the continuation of rehabilitation in a group setting. The cohort showed significant improvement in both measures of psychological and functional readiness after the program. The mean time from surgery to training was 8.1 months for the participants in this study. A further benefit of this program is that it delayed return to sport until after the 9-month post-operative mark, the minimal amount of time recommended before returning to sport.


  1. 2018 Nov;48(11):864-872


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