ACL Rehabilitation Plateaus Across Athlete Populations: Two Case Reports and a Clinical Framework for Identifying Functional Stagnation.

Background and Purpose Anterior cruciate ligament (ACL) rehabilitation typically follows a structured protocol for progressive recovery. However, not all subjects achieve expected functional milestones, despite adherence. Rehabilitation plateaus-defined as stagnation in physical progress-are often underrecognized in musculoskeletal cases. The concept of rehabilitation plateaus remains underexplored in musculoskeletal physiotherapy, particularly in ACL reconstruction recovery. The purpose of this case series was to explore clinical rehabilitation plateaus that occur during ACL reconstruction recovery, an underrecognized phenomenon in sports rehabilitation. # Design Retrospective case series. # Case DescriptionThe first subject was a 36-year-old recreational badminton player who exhibited psychological resistance to load training and inconsistent rehab compliance. The second was a 16-year-old sub-elite football (soccer) player who experienced a three-month interruption in formal rehabilitation following early discharge from club-based care. In both cases, rehabilitation plateaus were identified as the persistence of deficits in unilateral strength, dynamic control, and return-to-sport progression, based on repeated objective assessments including muscle strength testing, balance tasks, and functional running and sport-specific criteria.

Outcomes Both subjects demonstrated a period of stagnation during the transition from isolated strengthening to functional and sport-specific rehabilitation phases. This was identified through repeated physiotherapist-led assessments showing persistent quadriceps and hamstring strength asymmetry, reduced single-limb control, and delayed progression toward return-to-sport criteria beyond seven months post-operatively. Following targeted rehabilitation modifications-including aquatic therapy to facilitate load tolerance and perceptual-neurocognitive training to address movement control and decision-making, improvements were observed in strength symmetry, dynamic task performance, and functional sport-related activities.

Conclusion Rehabilitation plateaus represent a significant yet underrecognized challenge in ACL recovery. These clinical checkpoints often arise from mismatches between stimulus and readiness require adaptive, athlete-specific strategies to overcome. Adaptive strategies beyond standard protocols such as contextual movement planning, progressive overload, and perceptual training-may help resolve these plateaus and optimize outcomes. These cases emphasize the need to evolve beyond timeline-driven rehabilitation and embrace outcome-centered, personalized care in ACL physiotherapy.