Role of Relative Intentional Rotation of the Femoral Component in Robotic-Assisted Primary Total Knee Arthroplasty as a Tool for the Correction of Medial Flexion Laxity

Background Internal rotation of the femoral component (IR) is an often overlooked strategy to manage axial malalignment (AXM) in total knee arthroplasty (TKA). Proximal femoral pathologies can result in altered femoral condylar rotation, creating torsional incongruity that standard alignment protocols fail to address. While IR has been traditionally avoided due to several risks, robotic-assisted TKA (RA-TKA) may enable precise correction of such deformities using IR. This study aimed to identify the clinical and radiological indications for using relative IR to correct AXM, and to determine whether this strategy achieved balanced flexion gaps, with favourable outcomes. Methods A retrospective review analysed 219 consecutive primary RA-TKAs performed between March 2024 and March 2025 using an imageless, saw-based robotic system. Demographics, preoperative imaging, intraoperative robotic data, 1-year radiographic and functional outcomes were evaluated in cases that received ≥ 3° IR relative to the posterior condylar axis (set to 3° external rotation). Results Of the 219 knees operated on, 12 (5.48%) required relative IR  ≥ 3° (mean 5.46 ± 2.65°; range 3–10°). Preoperative CT imaging in these cases showed excessive external rotation of the femoral condyles (relative to the femoral head-neck axis). Balanced flexion gaps were achieved in all cases, reducing from mean 3.83 ± 2.78mm post-tibial resection to mean 0.71 ± 0.75mm at final assessment. Oxford Knee Scores improved from 19.5 ± 2.07 preoperatively to 34.58 ± 1.44 at follow-up. No cases reported issues of patellar maltracking or anterior knee pain, and radiologic evaluation showed no signs of component loosening or accelerated wear at 1-year follow-up. Conclusion Relative IR , guided by robotic assistance, safely corrects pathological AXM, achieving balanced flexion gaps and excellent outcomes without complications. This approach restores hip-to-knee rotational congruency, challenging the paradigm of uniform external rotation. Long-term studies are required to confirm durability. Level of Evidence Level III (Retrospective Cohort Study)