Poster 323: Factors Impacting Return to Sport Timing Following ACL Reconstruction
Authors: Gavia Alex , Wellsandt Mike , Werner David , Schelkopf Shelby , Tao Matthew , Wellsandt Elizabeth , Weaver Brittany 
Published: August 2023

Objectives: Forty-one percent of sports injuries are knee injuries. One-fifth of knee injuries involve the anterior cruciate ligament (ACL). The high incidence of ACL injuries results in approximately 129,000 ACL reconstructions in the United States each year. Timing of return to sport (RTS) after ACL reconstruction (ACLR) depends on clearance by the medical team, patients meeting objective RTS criteria, and patient selected timing. A criterion-based approach to RTS commonly includes measurements of quadriceps strength, hop performance, and subjective knee function to guide the decision-making of orthopedic surgeons and physical therapists regarding patient readiness and safety to RTS. Therefore, the purpose of this study was to assess patient-related predictors (age, sex, graft type, psychological readiness, and the duration of physical therapy) of time to pass RTS criteria. We hypothesized that patients with more positive psychological readiness, those who were still completing physical therapy, and male patients would pass RTS testing at earlier time points, while graft type and age would have no effect. Methods: Fifty-four participants between the ages of 10 and 25 years and within 5 to 15 months of ACL reconstruction who were planning to return to at least 50 hours per year of cutting and pivoting activities were included. Patients with a previous history of surgery to either knee or concomitant posterior cruciate ligament reconstruction were excluded from the study. Participants completed clinic testing when RTS was being planned. Testing included unilateral quadriceps strength in each limb (isometric at 90° knee flexion using a crane scale and 1-repetition maximum using a knee extension machine), 4 single-legged hop tests (single, crossover and triple hop for distance; 6-meter timed hop), and self-reported knee function (International Knee Documentation Committee Subjective Knee Form 2000 [IKDC], Global Rating Scale). In order to pass, participants needed scores of at least 90% symmetry for both quadriceps strength measures and all 4 single-legged hop tests as well as 90% on the IKDC and Global Rating Scale. Participants repeated clinic testing until they passed the entire testing battery in a single session. On the day of passing all RTS criteria, psychological readiness was assessed using the ACL Return to Sport after Injury (ACL-RSI) survey. The ACL-RSI is a valid and reliable outcome tool that assesses the participant’s emotional wellbeing, confidence in performance, and risk appraisal. An additional survey question was used to identify if participants were still participating in physical therapy (PT) at the time of passing RTS testing or when they had finished working with a physical therapist. PT was categorized as either a) <6 months of PT, b) 6-8 months of PT, or c) >8 months of PT or still currently in PT. Multivariate linear regression was used to assess the association between age, sex, graft type, ACL-RSI score, and duration of PT on the time to passing RTS testing after ACL reconstruction. An alpha level of p<0.05 was set a priori. Results: The mean age of the participants in this study was 17.3±2.7 years and 50% were female. Graft type and duration of physical therapy data are presented in Table 1. The mean time for passing all components of the RTS test battery was 10.3 ±2.6 months. At the time of passing RTS testing, the mean ACL-RSI score was 86.1±14.2%. Age, sex, graft type, ACL-RSI scores and duration of PT accounted for 44.5% of the variation in the time to pass RTS testing (p<0.001). Sex (β=-0.426; p<0.001), graft type (β=0.340; p=0.008), and age (β=0.194; p=0.111) were the strongest predictors of time to pass RTS testing with younger age correlating with shorter RTS times. Sex (Male: 8.6±3.1 months; Female: 11.1±3.5 months) and graft type (Hamstring: 7.7± 3.9 months; Quadriceps Tendon: 10.8±2.7 months; Patellar Tendon: 11.5±2.6 months; Allografts and IT band: 7.2±1.4 months), were significant predictors of time to pass RTS criteria while PT duration and ACL-RSI were not significant predictors. Conclusions: Female patients and patients with a patellar tendon or quadriceps graft took longer to meet objective RTS criteria after ACL reconstruction. Education with female patients and those with quadriceps and patellar tendon autografts may be required to establish realistic expectations for RTS readiness. While many factors impact graft choice, time to pass RTS criteria is an additional consideration for surgeons and patients. Additionally, previous studies have shown that male patients are more likely to experience graft retear following ACLR than females. This finding could be the result of male patients returning to sport earlier than females, giving the graft less time to heal. [Table: see text]