Performance-based Functional Tests for Return to Sport


When rehabilitating an athlete from a lower extremity injury, such as an ACL reconstruction (ACLR), how do you determine that athlete’s readiness to return to sport (RTS)? Do you base it on time since the injury or surgery? Do you use strength of the injured limb as compared to the non-injured limb? Is your decision-making process completely subjective, or does it include some sort of objective measure?

When it comes to the decision making process for determining an athlete’s readiness for RTS, there is no consensus. In a review of the literature about RTS following ACLR, Barber-Westin and Noyes found that 40% of the reviewed articles did not specify any criteria for RTS, and 32% of the studies used time as the only criterion. Other criteria found included:

rts graphic 3.png
  • isokinetic muscle strength of the quadriceps and hamstrings
  • knee effusion
  • ROM
  • self-report questionnaires
  • stability tests (e.g. Lachman's test)
  • objective performance tests

Among the studies that included performance tests, such as the single leg hop test, the necessary limb symmetry index (LSI) scores required to return to sport also varied.

Given the lack of consensus and the lack of use of outcome measures that simulate dynamic sport movements, it is not surprising that re-injury rates following lower extremity injuries are inexcusably high. Estimates for incidence of re-injury range from a four-fold increased risk following previous injury to six times higher risk of ACL re-injury within two years of ACLR to 80% re-injury rate following lateral ankle sprains. In order for an athlete to RTS, he or she should have returned to, or exceeded, his or her pre-injury level of strength and function. Clearly, with the high rate of re-injury, many athletes do not reach their prior level of function before returning to their respective sport.

In order to more accurately identify athletes’ functional capabilities as it relates to their sport, performance-based functional tests that simulate the dynamic movements required during sport should be utilized. Unfortunately, at this point, there is little quality research to establish the reliability, validity, or responsiveness of any performance-based outcome measure. According to Hegedus et al., the single leg hop test for distance is the only test that has evidence to suggest it can be responsive to rehabilitation following ACLR, and the single leg hop test for distance and hexagon hop tests were the only tests with evidence to suggest they can identify ankle instability in athletes.

Performance-based Functional Tests
Test Procedure*
Single Leg Hop for Distance (Single Hop) Athlete takes a single hop as far he/she can while not losing balance on landing. Best of three hops taken for each leg to determine limb symmetry index (LSI). Must reach LSI of >90% (injured leg at least 90% as far as non-injured).
Triple Hop for Distance Athlete takes three consecutive hops as far he/she can while not losing balance on landing. Best of three trials taken for each leg to determine limb symmetry index (LSI). Must reach LSI of >90% (injured leg at least 90% as far as non-injured)
6-m Timed Hop Athlete hops 6 meters as fast as he/she can while not losing balance on landing. Best of three trials taken for each leg to determine limb symmetry index (LSI). Must reach LSI of >90% (injured leg at least 90% as fast as non-injured)
Crossover Hop Athlete takes a three consecutive hops as far he/she can while not losing balance on landing. Best of three trials taken for each leg to determine limb symmetry index (LSI). Must reach LSI of >90% (injured leg at least 90% as far as non-injured)
Hexagon Hop (modified by Witchalls et al.) Athlete hops in six directions of hexagon while facing the same direction for 10 seconds on each leg. The total completed error-free hops are counted for each leg.
T-Test Athlete runs forward 10 meters, side-steps to the right 5 meters, side-steps to the left 10 meters, side-steps 5 meters back to the center, then runs backwards 10 meters
Star-Excursion Balance Test Athlete reaches and lightly touches as far as possible with non-stance leg in eight directions (anterior, anteromedial, medial, posteromedial, posterior, posterolateral, lateral, and anterolateral), returning leg to starting position between each direction. Also modified to only include anterior, posteromedial, and posterolateral directions.
*Procedure and scoring can vary based on source

For most performance-based outcome measures, it is not that the research says that they are poor tests. It is just that there is either a lack of research to establish them or the methodological quality of the studies has been poor. As is the case in most areas of physical therapy, more research is required to determine the reliability, validity, and responsiveness of performance-based RTS tests.

Rather than looking at single tests to determine RTS, perhaps a battery of tests that include elements of power, speed, agility, and dynamic balance would be more appropriate. In their 2011 study, Myer et al. utilized a battery of modified NFL combine tests that included both unilateral and bilateral tasks. While it still requires research, the University of Miami has had recent success with the use of the Comprehensive High-Level Activity and Mobility Predictor - Sport (CHAMP-S) in determining readiness for RTS following lower extremity injuries.

Performance-based functional tests may not be the only necessary measure to determine an athlete’s readiness to RTS, but they certainly provide objective values that can be tracked throughout the rehabilitation process. Compared to the available alternatives, performance-based functional tests better simulate the movement demands required during sports. How do you feel about the use of these tests in deciding when an athlete can RTS? Have you used them in your decision-making process in the past? Are you more likely to incorporate them now?


References:

1.    Abrams GD, Harris JD, Gupta AK, McCormick FM et al. Functional performance testing after anterior cruciate ligament reconstruction. Orthopaedic Journal of Sports Medicine. 2014;2(1):1-10.

2.    Barber-westin SD, Noyes FR. Factors used to determine return to unrestricted sports activities after anterior cruciate ligament reconstruction. Arthroscopy. 2011;27(12):1697-705.

3.    Clover J, Wall J. Return-to-play criteria following sports injury. Clin Sports Med. 2010;29:169-75.

4.    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.

5.    Hegedus EJ, Mcdonough SM, Bleakley C, Baxter D, Cook CE. Clinician-friendly lower extremity physical performance tests in athletes: a systematic review of measurement properties and correlation with injury. Part 1-the tests for knee function including the hop tests. Br J Sports Med. 2015;49(10):642-648.

6.    Hegedus EJ, Mcdonough SM, Bleakley C, Baxter D, Cook CE. Clinician-friendly lower extremity physical performance tests in athletes: a systematic review of measurement properties and correlation with injury. Part 2-the tests for the hip, thigh, foot and ankle including the star excursion balance test. Br J Sports Med. 2015;49(10):649-656.

7.    Kyritsis P, Witvrouw E. Return to sport after anterior cruciate ligament reconstruction: A Literature review. J Nov Physiother. 2014;4(1).

8.   Myer GD, Schmitt LC, Brent JL, Ford KR, et al. Utilization of modified NFL combine tasting to identify functional deficits in athletes following ACL reconstruction. J Orthop Sports Phys Ther. 2011;41(6):377-387.

9.   Paterno MV, Rauh MJ, Schmitt LC, Ford KR, Hewett TE. Incidence of second ACL injuries 2 years after primary ACL reconstruction and return to sport. Am J Sports Med. 2014;42:1567-73.

10.  Witchalls JB, Newman P, Waddington G, et al. Functional performance deficits associated with ligamentous instability at the ankle. J Sci Med Sport. 2013;16:89-93