Intraoperative Robot Navigation Assisted INFINITY Total Ankle Arthroplasty: Surgical Technique and Preliminary Outcomes

Research Type: Level 3 - Retrospective cohort study, Case-control study, Meta-analysis of Level 3 studies Introduction/Purpose: The INFINITY total ankle implant is a widely and successfully used option for total ankle arthroplasty (TAA). However, the fourth generation prosthesis requires a large amount of intraoperative fluoroscopy to accurately locate the alignment and this increases the operation time, which increases the risk of surgical incision complications. Intraoperative robot navigation (IRN) assistance technology can accurately locate the guiding pins of the tibial osteotomy guide plate before the operation begins, effectively reducing the operation time and intraoperative fluoroscopy frequency. The goal of this study is to introduce our experience of IRN assistance technique for INFINITY TAA, and its preliminary outcomes. Methods: The IRN assistance technique for INFINITY TAA was illustrated in figure 1. A retrospective, single-centered study was performed on 41 patients who underwent TAA with the INFINITY implant and with a less follow-up of three months. Twenty-three with traditional TAA technique (TT group), and 18 with IRN assistance technique (IRN group). The primary outcome of this study was evaluate the operation time, intraoperative fluoroscopy frequency (IFF), and incision relative complications. Secondary outcomes include accuracy of implants, range of motion (ROM), need for subsequent surgery, and Visual Analogue Score (VAS) for 500 meters walking. Results: The demographics parameters, including gender, age, side, BMI, smoker, diabetes, COFAS classifications, reached no significant difference (NSD). The mean operation time was significantly shorter in IRN group (83.3±8.5 min vs. 99.4±11.8 min, P<.001), and the mean IFF was significantly less in IRN group (72.2±9.6 times vs. 26.6±6.5 times, P <.001). In TT group, 4 patients with delayed healing (>3 weeks), and 2 with incision necrosis (need no subsequent surgery), and 2 with superficial infection (need debridement). In IRN group, 2 patients with delayed healing and 1 with incision necrosis and no need subsequent surgery. The incision relative complication rate was higher in TT group (38%) than IRN group (17%), but with NSD due to the sample size limitations. Other parameters reached NSD between groups. Conclusion: We found that the IRN assistance technique for INFINITY TAA can significantly shorten surgical time, reduce intraoperative fluoroscopy frequency, and might reduce incision related complications. The accuracy of its prosthesis implantation is no different from that of traditional surgery. Figure 1: A 58 years female with an end stage ankle osteoarthritis. The preoperative X-ray showed varus alignment with talar anterior displacement, and the overall alignment of the lower limb is good (A-E, ). The preoperative CT scan showed significant osteophyte hyperplasia in anterior tibia and talus (F,G). Operation steps: ① sterilized the surgical side and fix it in a supine neutral position, and fix the intraoperative navigation tracker to the tibial tuberosity (H,I). ② an O-arm CT was used to take the scans (J,K). ③ import CT images into intraoperative navigation devices (TINAVI), and plan the position of the tibial osteotomy guide plate fixation pins. The first pin is about 65mm above the distal tibial articular surface, and vertically to the tibial axis in the sagittal plane (L), and in the center of the ankle mortise on the horizontal plane (M,N). ④ use the navigation to place the first pin (O,P). ⑤ place the tibial osteotomy guide plate to further adjust the distance and inside/outside of the guide plate, and then place the second pin through the guide plate (Q,R). ⑥ after the two guide pins were placed, tourniquet inflated and the operation begins (S). The subsequent surgical steps are the same as the standard steps. For this patient, the tourniquet use was 60 min, and with 28 times intraoperative fluoroscopy (T-V). The postoperative X-ray showed good alignment and position of the prosthesis (W,X).