Who passes return to sport tests and which tests are most associated with a return to play after anterior cruciate ligament reconstruction?
Authors: Feller Kate Webster Julian 
Published: July 2020

Objectives: Although return to sport (RTS) testing has become popular following anterior cruciate ligament (ACL) reconstruction surgery, its utility is still questioned. The purpose of this study was to determine if there are age, sex and activity level differences between patients who pass a battery of self-report and functional tests at 6 months following surgery and to determine which tests are associated with a return to competition sport at 12 months. Methods: This was a prospective longitudinal study in which 450 patients who had undergone a primary ACL reconstruction were assessed at 6- and 12-months following surgery. Patients with a prior contralateral ACL injury, or who did not regularly participate in sport prior to injury were not included. There were 176 females and 274 males with a mean age of 25 (SD = 4) years. Six return to sport tests were conducted at 6 months and included two patient self-report measures: IKDC subjective knee form to measure symptoms and function and the ACL-RSI scale to measure psychological readiness to RTS; and four functional measures: single and triple hop for distance and isokinetic quadriceps strength measured at 60 and 180 deg/sec. Limb symmetry index scores of ≥90 for functional tests and IKDC scores of ≥85 and ACL-RSI scores ≥65 were considered indicators of satisfactory recovery. Proportional statistics and contingency analysis were used to determine associations between age (<21 vs. ≥21 years), sex, sport level (Level I vs. Levels II/III sports) and meeting test criteria and return to sport. Results: Only 13 (3%) patients met all 6 of the test criteria at 6 months following ACL reconstruction surgery and 83 (18%) patients did not pass any of the tests. A significantly greater proportion of younger patients passed all the functional tests (p<0.01). A greater proportion of males passed the IKDC threshold for symptoms and function (30% vs. 21% p=0.03) but there were no other sex differences. Patients who had played Level I sports before injury had the same pass rates as those who played Level II or III sports. Patients who passed the threshold for the IKDC and ACL-RSI scales had 4 (95% CI 3-6) times the odds of returning to competition sport at 12 months (p<0.0001). Conversely, meeting the threshold for either quadriceps strength test or either hop test at 6 months was not associated with a return to sport at 12 months. Conclusion: Few patients pass all the thresholds of common tests which are used to assess the ability to return to sport at 6 months following ACL reconstruction surgery although younger patients have higher rates of passing functional tests. This has implications for the utility of such testing and when patients should be cleared to return to sport. Patients may base their decision to return to sport on self-perceived symptoms and psychological readiness more than physical performance and muscle strength. These findings have implications for how return to sport testing may be used to facilitate a return to sport following this surgery.