Joint line is restored in robotic-arm-assisted total knee arthroplasty performed with a tibia-based functional alignment

• Published in: Archives of orthopaedic and trauma surgery 2021-12, Vol.141 (12), p.2175-2184
• Main Authors: Zambianchi, Francesco, Bazzan, Gabriele, Marcovigi, Andrea, Pavesi, Marco, Illuminati, Andrea, Ensini, Andrea, Catani, Fabio
• Format: Article
• Language: English
• Subjects: Joint replacement surgery; Joint surgery; Knee Arthroplasty; Medicine; Medicine & Public Health; New Technologies in Knee Arthroplasty; Orthopedics; Patient satisfaction; Robotics
• ISSN: 0936-8051; 1434-3916
• DOI: 10.1007/s00402-021-04039-z

Introduction Functional alignment (FA) in total knee arthroplasty (TKA) has been introduced to restore the native joint line obliquity, respect the joint line height and minimize the need of soft tissue releases. The purpose of this study was to assess the intraoperative joint line alignment and compare it with the preoperative epiphyseal orientation of the femur and tibia in patients undergoing robotic-arm-assisted (RA)-TKA using FA. Materials and Methods This retrospective study included a consecutive series of patients undergoing RA-TKA between February 2019 and February 2021. The joint line orientation of the femur and tibia in the three-dimensions was calculated and classified on preoperative CT-scans and compared with the intraoperative implant alignment. The tibial cut was performed according to the tibial preoperative anatomy. The femoral cuts were fine-tuned based on tensioned soft tissues, aiming for balanced medial and lateral gaps in flexion and extension. Results A total of 115 RA-TKAs were assessed. On average, the tibial component was placed at 1.8° varus (SD 1.3), while the femur was placed at 0.8° valgus (SD 2.2) and 0.6° external rotation (SD 2.6) relative to the surgical transepicondylar axis. Moderate to strong, statistically significant relationships were described between preoperative tibial coronal alignment and tibial cut orientation ( r  = 0.7, p