From Past to Future: Emergent Concepts of Anterior Cruciate Ligament Surgery and Rehabilitation

Background/Objectives: Anterior cruciate ligament (ACL) injuries continue to present significant clinical and rehabilitative challenges. Despite advances in surgical techniques and rehabilitation protocols, persistent reinjury rates and increased pressure for early return to sport require a critical reassessment of current practices. This narrative review provides a comprehensive overview of the evolution, current standards, and future directions of ACL treatment and rehabilitation. Additionally, we present original data evaluating the effectiveness of brace-free rehabilitation following ACL reconstruction (ACL-R). Methods: The review synthesizes developments in surgical techniques and rehabilitation strategies, including blood flow restriction training, anti-gravity treadmill use, and return-to-play criteria. Complementary to the literature, we report results from a controlled, longitudinal study (n = 137) comparing isokinetic strength and functional outcomes between brace-based and brace-free early rehabilitation after ACL-R using hamstring grafts. Results: The literature reflects a shift from time-based to criteria-driven rehabilitation, emphasizing individualization and functional readiness. Our original data revealed no significant differences in quadriceps and hamstring torque production between groups at 16, 26, and 52 weeks postoperatively. Statistical parametric mapping confirmed the non-inferiority of brace-free rehabilitation in terms of isokinetic performance. Conclusions: ACL therapy has evolved toward personalized, function-oriented rehabilitation. Our findings suggest that postoperative bracing may be unnecessary in many cases, supporting a more progressive approach. Future developments may include markerless motion analysis, AI-supported rehabilitation, and digital health tools to further individualize care.