Are You Ready to Play?

PT Blog   •   December, 2018


“Knowing yourself is the beginning of all wisdom.”  – Aristotle

Here are some statistics concerning ACL injuries in the United States1:

  1. Approximately 350,000 ACL reconstructions (ACLR) are performed each year.
  2. Patients who undergo ACLR: 79% develop knee osteoarthritis and 20% suffer re-injury within 2 years.
  3. ACL injuries are INCREASING for Division 1 collegiate athlete and youth athletes with some literature quoting a 60% higher prevalence in ACLR in athletes between the ages of 6  to 18 in the past 20 years.
  4. 25% of youth athletes who suffer an ACL injury will sustain a second injury in their athletic career.

These alarming statistics are shedding some light on the epidemic that is ACL injury, and highlighting the fact that change needs to be made. Copious literature exists on biomechanical factors that lead to ACL tears and prevention programs aimed at correcting these modifiable risk factors. Consequently, prevention is not 100% effective, so other measures need to be used to determine the health of a surgically reconstructed ACL. And that is the role of Return to Sport testing: functional assessments intended to create objective data to substantiate safe return to sport activity. It is no longer enough to discharge from a 3-month physical therapy program with full active range of motion, 5/5 strength with manual muscle testing, pain-free activities of daily living, and a normal gait pattern and simply believe that you are ready to strap on the pads, buckle the chinstrap, lace up the cleats, etc…

Return to Sport Test and Measures

The literature is constantly updated and evolving, but a 2015 meta-analysis concluded that “65% [of athletes] returned to their preinjury level of sport and 55% returned to competitive sport. This means that 1 in 3 individuals did not return to his or her previous level of sports participation, and 1 in 2 did not return to competitive sport after surgery2 

Below, discussion will be directed toward various physiological tests and measures validated for as return-to-sport testing following ACLR:

  1. Isokinetic testing3:
    • Isokinetic testing seeks to determine the maximal torque, percent of peak torque to body weight, and hamstrings-quadriceps peak torque ratio at 60, 180, 300°/s.
    • Criteria for RTS: 85% of the uninvolved limb
  2. Agility testing: T-Test Agility Run4
  • Begin at start, (1) sprint 10 meters forward, (2) side shuffle 5 meters right to the cone, (3) side shuffles 10 meters left to the opposite cone, (4) side shuffles 5 meters back to the middle, (5) backpedal to the finish.
  • Criteria for RTS: 10-15% preinjury level


3. Hop Testing: Single Leg Hop, Triple Hop, Triple Crossover Hop4

  • For single leg hop testing, athletes were instructed to perform three hops for distance on each leg and an average distance was calculated [proper landing without loss of balance was required]
  • For triple hop and triple crossover hop, each leg hopped three consecutive times [with crossover having to jump over a middle line each time. Total distance was calculated.
  • Criteria for RTS: 90-95% limb symmetry index (LSI)


4.Stability Testing: Star Excursion Test6

  • The patient is asked to stand on one leg without lifting heel or losing balance with hands on hips and perform the following three movements: reaching with involved foot as far anterior, posteromedial, and posterolateral as possible. Distance covered is recorded for each leg.
  • Criteria for RTS: 90% limb symmetry index

                    Star Excursion Figure

Psychological and time factors are also both integrally involved in a full return to sport, with one article stating that “the main reasons for not returning were not trusting the knee (28%), fear of a new injury (24%) and poor knee function (22%)7. Another article by Grindem et al reported “a 50% reduction in risk of knee re-injuries for each month that RTS is delayed beyond 6 months8.”

A comprehensive assessment of the entire patient is crucial for a safe return to sport designation, from an impairment-based perspective, to a functional capacity perspective, and finally a psychological and motivational perspective. All patients need healthcare professionals to guide and direct their care, not just in the immediate rehabilitation setting but also in a thorough strength and conditioning environment to ensure that their body is able to withstand all demands that their sport requires.

Contributing Author Credit: W. Evan Stringfellow, PT, DPT, CSCS, Cert. DN

Edited by: Ashley Theobald, DPT

Photo by: rawpixel on Unsplash


  1. Nessler T, Denney L, Sampley J. ACL Injury Prevention: What Does Research Tell Us? Curr Rev Musculoskelet Med. 2017;10(3):281-288.
  2. Ardern CL, Taylor NF, Feller JA, Webster KE. Fifty-five per cent return to competitive sport following anterior cruciate ligament reconstruction surgery: an updated systematic review and meta-analysis including aspects of physical functioning and contextual factorsBr J Sports Med. 2014;48:1543-1552
  3. Kyritsis P, Bahr R, Landreau P, et al. Likelihood of ACL graft rupture: not meeting six clinical discharge criteria before return to sport is associated with a four times greater risk of rupture. Br J Sports Med 2016;50:946-951.
  4. Rambaud AJM, Semay B, Samozino P, et al. Criteria for Return to Sport after Anterior Cruciate Ligament reconstruction with lower reinjury risk (CR’STAL study): protocol for a prospective observational study in France. BMJ Open. 2017;7:e015087. doi:10.1136/ bmjopen-2016-015087
  5. Kyritsis P , Bahr R , Landreau P , et al. Likelihood of ACL graft rupture: not meeting six clinical discharge criteria before return to sport is associated with a four times greater risk of rupture. Br J Sports Med 2016;50:946–51.doi:10.1136/bjsports-2015-095908
  6. Gribble PA, Hertel J, Plisky P. Using the Star Excursion Balance Test to assess dynamic postural-control deficits and outcomes in lower extremity injury: a literature and systematic review. J Athl Train. 2012;47(3):339-57.
  7. Ardern CL, Österberg A, Tagesson S, et al. The impact of psychological readiness to return to sport and recreational activities after anterior cruciate ligament reconstruction. Br J Sports Med. 2014;48:1613-1619.
  8. Grindem  H, Snyder-Mackler  L, Moksnes  H, et al. Simple decision rules reduce re-injury risk after anterior cruciate ligament reconstruction: the Delaware–Oslo cohort study. Br J Sports Med. Published Online First: 9 May 2016.

About the Author:

Ashley Theobald, D.P.T. – Ashley was born and raised in a small town in Alabama. She attended the University of South Alabama and was an advanced undergraduate student completing her Bachelor of Science degree in pre-professional health sciences in 2012. She then graduated with her doctorate in physical therapy in 2014. During her first year of PT school she met and married her husband, Ben. They moved to Nashville, TN where she worked for 3 years in an outpatient clinic full time and at Vanderbilt Stallworth Rehabilitation Hospital PRN. She is now working for ATI Physical Therapy full-time in Greenville, SC. She has been an avid health and fitness fan playing softball growing up, tennis in high school, and completing 2 half-marathons in college. She enjoys traveling overseas and has completed 2 short-term medical mission trips for physical therapy in the Dominican Republic (2013) and Haiti (2015), with intentions of returning yearly.
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