The ACL Battery

IKDC, ACL-RSI PASS/FAIL. Subjective measures, both knee function and readiness to play have been strongly associated with successful return to sport rates with Ardern et al. stating “psychological readiness to return to sport and recreation was the factor most strongly associated with returning to the preinjury activity” in their 2014 publication. Specifically, scores below 47 points on the ACL-RSI “indicated that a patient was at risk of not returning to sport” (Faleide et al. 2021) and further, scores below 55 points at 6 months post-surgery “were associated with a greater risk of unsuccessful RTS at 1 year after surgery” (Kitaguchi et al., 2020). Nevada Physical Therapy requires 65 points or higher on the ACL-RSI as Ardern et al. state this was the threshold for a “satisfactory recovery” (2014). Additionally, aside from psychological readiness, “reduced IKDC score distinguish patients who are unable to return to preinjury sports participation because of fear of reinjury/lack of confidence” (Lentz et al., 2015)

A-P Knee Laxity: Successful return to sport has been associated with the amount of post-surgical ACL laxity with an increase of >3mm in AP laxity associated with increased risk of reinjury (J Orthop 2016). Additionally “...a 4-mm side-to-side difference was the prognostic threshold for failure to return to sports with a positive predictive value of 86% and specificity of 98%” and “a 1-mm increase in side-to-side difference was associated with a 50% higher probability of having a poor/fair ARPEGE score” (Jordan et al. 2022)

Knee Extension Strength (Isometric and Peak Power). PASS/FAIL: Persistent quadriceps strength has been linked to poor Return to Sport testing; quadriceps strength collected at return to activity were associated with greater knee-joint function, greater readiness to return to functional activity, and more positive emotions connected to the injury process “QF - quadricep femoris strength deficits predicted hop test performance beyond the influences of graft type, presence of meniscus injury, knee pain, and knee symptoms.” (Scmitt et al., 2012) (Knapik et al., 1991) In line with current research, Nevada Physical Therapy requires quad strength, when normalized to body mass, to be 1.0 ft·lb/ lb BW as individuals testing at or above this threshold “had over eight times higher odds of reporting an IKDC score ≥90%.” (Pietrosimone et al. 2016). In other words, athletes demonstrating a quadriceps peak torque of 3.0 N·m/kg (converted to 1.0 1.0 ft·lb/ lb BW) would be “expected to have KOOS Sport, KOOS QoL, and IKDC scores that were approximately 17 points higher than an individual with quadriceps peak torque of 2.0 N·m/kg” (Van Wyngaarden et al. 2021)

Nordic Hamstring Proficiency (>70 deg), PASS/FAIL: Performance of the Nordic Hamstring Exercise is correlated with eccentric hamstring strength with lower (more open) knee flexion angles demonstrative of higher eccentric strength. Nordic Hamstring Exercise performance has been suggested to reduce ACL risk by improving eccentric hamstring strength (Monajati et al. 2016), a risk factor associated with ligament injury (Myer 2009) as well as increased ACL loading with sidestep cutting (Wienhandl et al. 2014)

Core Weakness, PASS/FAIL Decreased Single Leg Squat and/or Decreased Side Plank/Lateral Chain Strength may be predictive of ACL re-injury (Hegedus et al. 2016, Kyritsis et al., 2016)

Quad:Hamstring Ratio, PASS/FAIL Research suggests decreased quadriceps to hamstring strength may be a predictor for ACL re-injury (Knapik et al., 1991) and “for every 10% decrease in the hamstring to quadriceps strength ratio there was a 10.6 times higher risk of sustaining an ACL graft rupture (Kyritsis et al., 2016)

Jump Testing (Force Plate Testing; Countermovement Jump, Single Leg Vertical, Double Leg Repeated Hop Test) - Vertical jump testing is superior to horizontal hop testing in identifying knee function deficits in patients undergoing ACL reconstruction; (Kotsifaki et al. 2021) and athletes demonstrate continued movement compensation strategies and deficits with vertical jump testing at time of return to sport after ACLR (Kotsifaki et al, 2022)

Anterior Y-Balance PASS/FAIL Athletes who had a greater than 4cm difference in anterior Y-balance scores at 12 weeks were shown to not achieve 90% or greater lower limb symmetry at return to sport testing. (Garrison et al., 2015)

5-10-5, PASS/FAIL Decreased T-test speeds compared to normative data are associated with increased ACL re-injury. (Kyritsis et al., 2015)

Chronic Workload Established, PASS/FAIL “when an athlete's training and playing load for a given week (acute load) spikes above what they have been doing on average over the past 4 weeks (chronic load), they are more likely to be injured” (Gabbett et al. 2015) “tendons are at lowest risk with consistent workloads and susceptible to injury with sudden upgrades in workload” (Orchard et al., 2015)

Complete Nevada PT Return to Sport Testing, PASS/FAIL Of those that actually had objective Return to Sport testing, only 11-33% of patients actually met them. (Paterno et al. 2018, Welling et al. 2019) These numbers are consistent with previous publications showing an average of only 30% of patients meeting testing criteria to be cleared for returning to sport activity. (Herbst et al. 2015, Logerstedt et al, 2014, Toole et al., 2017) Completing the established Return to Sport Criteria detailed above may decrease re-injury by 84% (Grindem et al., 2016) and has been shown to facilitate a 4x higher rate of return to elite athletics (Kyritsis et al., 2015).