Efficacy of a novel, fluoroscopy-based robotic-assisted total hip arthroplasty system in restoring limb length and offset

Introduction. Optimizing leg length discrepancy (LLD) and restoring global and femoral offset (GO, FO) are integral to improving the stability and longevity of total hip arthroplasty (THA). A novel robotic-assisted THA (RA-THA) platform has been developed to utilize pre-operative templating and intraoperative fluoroscopic imaging to guide the restoration of native biomechanics. We sought to evaluate the effectiveness of this novel, pin-less, fluoroscopy-based RA-THA system to restore templated LLD and offset parameters. Materials and Methods. We performed a retrospective analysis on a consecutive series of 98 patients who underwent fluoroscopy-based RA-THA at our institution. The primary outcomes were the differences between preoperatively templated LLD, GO, and FO parameters with intraoperatively achieved parameters measured by the robotic system and with postoperatively achieved parameters measured from postoperative radiographs. Results. The mean difference between achieved and preoperatively templated values of LLD (−1.5 ± 5.5 mm), GO (−0.1 ± 5.5 mm), and FO (−0.1 ± 5.4 mm) were all within − 1.5 mm of establishing equalized leg length and offset. The proportion of patients with a difference in achieved and templated values < 10 mm were 92% for LLD, 91% for GO, and 93% for FO. For 43 of the 98 (44%) patients in this study, the surgeon referenced intraoperative robotic data to adjust femoral components from the preoperative plan in order to optimize LLD and offset parameters. Conclusions. The results of our present study demonstrated that fluoroscopy-based RA-THA is associated with high levels of accuracy in restoring key biomechanics of the hip. In a large number of patients, the surgeon used intraoperative robotic data to more closely achieve LLD and offset goals. This demonstrates the ability of this system to merge preoperative data with intraoperative, actionable data provided by the robotic software to restore leg length and global/femoral offset parameters. Words: 279/ 300.