Robotic Arm Assisted Total Knee Arthroplasty: Addressing 1-12 Degrees Valgus Knees

The purpose of this work was to determine the number of soft tissue releases and component orientation of valgus cases performed with Robotic-Arm Assisted total knee arthroplasty (RATKA).This study was a retrospective chart review of cases performed by a single surgeon from July 2016 to December 2017. 72 RATKA cases were defined as having a valgus deformity pre-operatively. Patient demographics and intraoperative surgical details were collected, including initial and final 3D component alignment, knee balancing gaps, full or partial releases. Post- operatively, radiographs, adverse events, and reduced WOMAC pain and KOOS Jr scores were collected at 6 months post-operatively.Pre-operatively, knee deformities ranged from 1o to 12° with fixed flexion contracture. All knees were corrected within 2.5 degrees of mechanical neutral. Medial and lateral gaps were balanced in extension 100% of cases and flexion 93% of cases.Radiographic evidence suggested well seated and well-fixed components. No revision and re- operation is reported. Patient reported outcomes measures collected at 6-month follow up indicated an improvement in WOMAC pain score from 9.6 to 3.2 and improvement in KOOS Jr from 44.7 to 74.4 points.In this retrospective case review, soft tissue releases were not needed to address valgus knees ranging from 1-12° of deformity. The surgeon was able to balance the knee with bone resections and avoid disturbing the soft tissue envelope. While this study has a number of limitations, RATKA for valgus knees should continue to be investigated in a multicenter study.