Functional knee positioning in total knee arthroplasty: Rationale and current evidence

• Published in: Journal of Joint Surgery and Research
• Main Authors: Vermue, Hannes, Andriollo, Luca, Servien, Elvire, Batailler, Cécile, Lustig, Sébastien
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2025
• Subjects: Balance; Functional alignment; Functional knee positioning; Joint line; Total knee arthroplasty; Functional alignment; Total knee arthroplasty; Functional knee positioning; Balance; Joint line
• ISSN: 2949-7051; 2949-7051
• DOI: 10.1016/j.jjoisr.2025.06.005

This narrative review aimed to evaluate the principles and outcomes of functional knee positioning (FKP) in total knee arthroplasty (TKA), a modern, patient-specific, robot-assisted technique designed to restore native limb alignment while preserving soft tissue balance. A systematic literature search was conducted on March 22, 2025 across PubMed, Embase, and the Cochrane Library using the terms “functional alignment”, “functional knee positioning”, and “total knee arthroplasty.” A total of 1533 articles were identified, with relevant studies selected based on their contribution to understanding FKP principles, soft tissue balance, component positioning, and clinical outcomes. FKP employs a six-step, image-based planning strategy to reconstruct individual three-dimensional alignment and achieve ligament balance without soft tissue releases. Compared with mechanical and kinematic alignment, FKP more reliably achieves intra-operative balance, especially in the sagittal plane, and minimizes coronal and axial malalignment. FKP has shown consistent implant positioning accuracy and significantly low rates of soft tissue release. Clinical studies report high early post-operative scores, with some studies demonstrating superior outcomes in KOOS, WOMAC, and patient satisfaction compared with conventional strategies. FKP maintains outcomes across deformity types, implant designs, and Coronal Plane Alignment of the Knee (CPAK) phenotypes. FKP represents a reproducible, anatomy-respecting alignment technique in TKA, with excellent early to midterm functional results and high patient satisfaction. By integrating robotic planning and intra-operative soft tissue assessment, FKP enables a highly personalized and biomechanically optimized alternative to conventional alignment strategies. Standardization of techniques and long-term outcome studies are needed to fully establish its role in routine clinical practice. •Functional knee positioning (FKP) tailors total knee arthroplasty to patient anatomy and soft tissue balance.•FKP restores native joint line and alignment through individualized 3D planning.•Early results show that FKP improves function and reduces soft tissue releases.