Robotic-assisted total knee arthroplasty in extra-articular post-traumatic deformities: A case series with one-year...

PurposeExtra-articular femoral or tibial malunion can distort anatomical landmarks, compromise the reliability of conventional alignment guides, and complicate total knee arthroplasty (TKA). Robotic-assisted TKA (RA-TKA) may improve the precision and reproducibility of bone preparation and component positioning in these anatomically challenging cases. This study reports one-year clinical and radiographic outcomes after single-stage RA-TKA performed without corrective osteotomy in patients with post-traumatic extra-articular deformities.MethodsThis retrospective case series included nine patients (ten knees; one bilateral case) with symptomatic Kellgren-Lawrence grade 4 post-traumatic knee arthritis and associated extra-articular deformity who underwent CT-based RA-TKA using the Robotic Arm Interactive Orthopedic System (RIO; Mako SmartRobotics™, Stryker). Clinical outcomes included Knee Society Score (KSS 2011), Knee Injury and Osteoarthritis Outcome Score (KOOS), visual analogue scale (VAS) pain, and range of motion (ROM) assessed preoperatively and postoperatively at 2 weeks, 6 weeks, 3 months, and 1 year. Radiographic alignment was assessed using Hip-Knee-Ankle (HKA) angle on scanograms and arithmetic hip-knee-ankle angle (aHKA) derived from CT-based planning and intraoperative console values.ResultsMean HKA improved from 168.3° ± 3.8° preoperatively to 177.7° ± 1.4° postoperatively (mean correction 9.4° ± 2.8° toward neutral). Mean aHKA improved from -4.6° ± 5.0° to -0.6° ± 2.7° (mean correction +4.0°). Mean ROM increased from 95.5° ± 21.7° preoperatively to 119.5° ± 17.4° at 1 year. PROMs improved across timepoints. No major complications, including tracker pin site infection or periprosthetic fracture, were observed.ConclusionIn selected patients with post-traumatic extra-articular deformity deemed suitable for intra-articular compensation, single-stage RA-TKA without corrective osteotomy achieved consistent coronal alignment correction toward neutral and meaningful improvements in pain, ROM, and patient-reported outcomes at 1 year.