Total knee arthroplasty after anterior cruciate ligament reconstruction with the use of image-based robotic technology and functional alignment.

Background: Total knee arthroplasty (TKA) in patients with prior anterior cruciate ligament reconstruction (ACLR) presents unique challenges due to altered knee kinematics, residual instability, and fixation implants that may interfere with implant positioning. Image-based robotic-assisted TKA enables the functional alignment (FA) strategy that accounts for individual bony anatomy, ligamentous laxities, and anterior compartment characteristics.

Surgical technique: This technique involves a CT-based robotic workflow where femoral and tibial components are planned based on patient-specific alignment and soft tissue balance. Intraoperative assessment with a digital tensioning device guides fine-tuning of flexion and extension gaps, ensuring balanced implant positioning while minimizing soft tissue releases. Fixation implants from prior ACLR are identified using robotic navigation, allowing for targeted adjustments such as selective removal or controlled elevation of components to avoid excessive bone loss. Patellar tracking is dynamically evaluated with a probe, facilitating real-time adjustments to optimize mediolateral tracking and anterior offset.

Discussion: Given the altered biomechanics in post-ACLR knees, FA may provide a physiological alignment by accommodating native laxities and reducing the risk of residual instability. Additionally, robotic guidance allows for precise management of fixation implants, ensuring optimal implant positioning and bone preservation. While further studies are needed, robotic-assisted FA represents a promising approach for enhancing outcomes in TKA for post-ACLR patients.