Abstract Title Comparison of Clinical Outcomes in Patients with Primary Versus Ipsilateral Revision ACL Reconstruction

Background Up to 30% of young active patients with a previous anterior cruciate ligament reconstruction (ACLR) suffer a second ACL rupture within the first two years after surgery. To our knowledge, few studies have determined if individuals who undergo a second ACLR report worse knee function and psychological response to injury recovery when compared to individuals who undergo primary ACLR. The aim of this study is to investigate whether there is a difference in functional and psychological outcomes in patients who have undergone an ipsilateral revision ACL reconstruction compared to patients with a primary ACL reconstruction.

Methods Data were combined from ongoing retrospective and prospective cohort studies at a single medical center. Patients were included in this study if they were 13-40 years old, underwent primary uncomplicated ACLR or ipsilateral revision ACLR at our institution, and participated in our standardized return to sport testing protocol at least 5 months post-ACLR. Patients were excluded if they experienced perioperative complications that resulted in a delayed standard of care. Surgical characteristics were confirmed via chart review. Primary outcomes of interest included knee function measured by the International Knee Documentation Committee Subjective Knee Evaluation score (IKDC), psychological readiness for return to sport measured by the ACL-RSI score, and isokinetic (60°/s) quadriceps and hamstring strength limb symmetry index (%). Patient-reported and strength outcomes were compared between patients in the primary and revision ACLR groups using ANCOVA while controlling for the effects of age and time since surgery. A-priori alpha level was established as p < 0.05.

Results Patients in the primary ACLR group were younger (p=0.002) and the groups also differed based on graft source (p=0.013), and medial meniscus (p=0.041) treatment (meniscectomy, repair, or no treatment) at the time of ACLR. After accounting for time since surgery and age, there were no significant differences between groups for IKDC score (p=0.740), ACL-RSI score (p=0.762), nor knee extension strength LSI (p=0.393); however, the primary ACLR group displayed greater knee flexion strength LSI (p=0.020).

Conclusion Patients that underwent revision ACLR had similar outcomes in terms of patient-reported psychological readiness to return to sport, patient-reported knee function, and knee extension strength compared to those who underwent primary ACLR. However, the revision ACLR group demonstrated decreased knee flexion strength. This finding may suggest that patients undergoing recovery from revision ACLR may benefit from increased incorporation of hamstring-specific strength building exercises during rehabilitation to restore knee flexion function and prevent future injury.