Imageless robotic-assisted system is associated to effective restoration of the joint line and posterior condylar offset in revision total knee arthroplasty.

introductionRevision total knee arthroplasty (rTKA) rates are rising. Novel technologies such as imageless robotic-assisted systems have been created to increase accuracy and precision during these difficult cases, though there is a lack of evidence detailing the effectiveness of these systems. The efficacy of imageless robotic-assisted rTKA in restoring joint line and other radiographic measurements, intra-operative outcomes, clinical outcomes, and patient-reported outcome measures (PROMs) were evaluated in this study. MATERIALS AND

methodsThis was a retrospective review of patients undergoing rTKA using an imageless robotic-assisted system. Patients undergoing rTKA for both aseptic and septic failures were included. Demographics, intraoperative data, radiographic outcomes, and PROMs including Patient Reported Outcome Measurement Information System (PROMIS) Pain Interference, PROMIS Physical Function, PROMIS Depression and Knee Injury, Visual Analogue Scale (VAS), and Knee Injury and Osteoarthritis Outcome Score (KOOS) were analyzed. All patients received at least 1 year of follow-up. Preoperative and postoperative weight-bearing hip-to-ankle calibrated radiographs were used to assess joint line restoration using the adductor tubercle as a reference point. Posterior condylar offset (PCO) was measured on calibrated preoperative and postoperative lateral weightbearing films.

resultsA total of 84 patients were included. Postoperative mean VAS pain (p < 0.0001), PROMIS Pain Interference (p = 0.03), and PROMIS Depression (p = 0.03) demonstrated improvement compared to preoperative scores. KOOS decreased in the postoperative period (p = 0.0006). The joint line was restored within 5 mm of the contralateral side in 77.4% (n = 65/84 patients) of patients. Postoperative and preoperative PCO to femoral diaphysis ratios were similar (ratio = 0.83 and 0.83, respectively). One-year complication rates were low amongst this patient cohort, with notable mean length of hospital stay of 2.3 ± 2.5 days and 88.1% (n = 74/84) of patients discharging home.

conclusionsPatients undergoing rTKA with an imageless robotic-assisted system demonstrated adequate joint line restoration, maintenance of the PCO, improvement in pain scores, and low rates of post-operative complications. Further research is needed to directly investigate how imageless robotic-assisted rTKA may lead to quicker, safer discharge from the hospital as compared to conventional rTKA. LEVEL OF EVIDENCE: Level III, diagnostic study.