This study determined if robotic-arm assisted total knee arthroplasty (RATKA) allows for more accurate and precise bone cuts and component position to plan compared with manual total knee arthroplasty (MTKA). Specifically, we assessed the following: (1) final bone cuts, (2) final component position, and (3) a potential learning curve for RATKA. On six cadaver specimens (12 knees), a MTKA and RATKA were performed on the left and right knees, respectively. Bone-cut and final-component positioning errors relative to preoperative plans were compared. Median errors and standard deviations (SDs) in the sagittal, coronal, and axial planes were compared. Median values of the absolute deviation from plan defined the accuracy to plan. SDs described the precision to plan. RATKA bone cuts were as or more accurate to plan based on nominal median values in 11 out of 12 measurements. RATKA bone cuts were more precise to plan in 8 out of 12 measurements ( ≤ 0.05). RATKA final component positions were as or more accurate to plan based on median values in five out of five measurements. RATKA final component positions were more precise to plan in four out of five measurements ( ≤ 0.05). Stacked error results from all cuts and implant positions for each specimen in procedural order showed that RATKA error was less than MTKA error. Although this study analyzed a small number of cadaver specimens, there were clear differences that separated these two groups. When compared with MTKA, RATKA demonstrated more accurate and precise bone cuts and implant positioning to plan.

Although several studies highlight the advantages of robotic arm-assisted total knee arthroplasty (RA-TKA), few investigate its intraoperative outcome. Therefore, the purpose of this study was to analyze the RA-TKA's ability to assist with intraoperative correction of: (1) flexion and (2) extension gaps, as well as its ability to (3) accurately predict implant sizes. Additionally, in this RA-TKA cohort, length of stay, complications, and readmissions were assessed. A total of 335 patients who underwent RA-TKA were included. The robotic software virtually measured the intraoperative prebone cut extension and flexion gaps. Differences in medial versus lateral prebone cut extension and flexion gaps were calculated. A total of 155 patients (46%) had an extension gap difference of between -2 and 2 mm (mean, -0.3 mm), while 119 patients (36%) had a flexion gap difference of between -2 and 2 mm (mean, -0.6 mm). Postbone cut differences in medial versus lateral flexion and extension gaps were measured. Balanced knees were considered to have a medial and lateral flexion gap difference within 2 mm. The robot-predicted implant size was also compared with the final implant size. Additionally, lengths of stay, complications, and readmissions were assessed. All patients achieved a postbone cut extension gap difference between -1 and 1 mm (mean, -0.1 mm). A total of 332 patients (99%) achieved a postbone cut flexion gap difference of between -2 and 2 mm (mean, 0 mm). For 98% of prostheses, the robotic software predicted within 1 implant size the actual tibial or femoral implant size used.The mean length of stay was found to be 2 days. No patients suffered from superficial skin infection, pin site infections or fractures, soft tissue damage, and no robotic cases were converted to manual TKA due to intraoperative complications. A total of 8 patients (2.2%) were readmitted; however, none were directly related to robotic use. The robotic software and use of a preoperative computed tomography (CT) substantially helped with intraoperative planning and accurate prediction of implant sizes. Therefore, based on the results of this study, the RA-TKA device does, in fact, provide considerable intraoperative assistance.

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Standard total hip arthroplasty (THA) is the established surgical treatment for patients older than 65 years with progressive osteoarthritis but survivorship curves wane in patients younger than 50. Resurfacing hip arthroplasty (RHA) is an alternative for younger, active patients reportedly providing superior range of motion. Quantitative investigation of functional recovery following arthroplasty may elucidate limitations that aid in device selection. Although limited long-term kinematic data are available, the early rate of recovery and gait compensations are not well described. This information may aid in refining rehabilitation protocols based on limitations specific to the implant. We presumed hip motion and forces for subjects receiving RHA are more similar to age-matched controls during physically demanding tasks, such as stair negotiation, at early time points than those for THA. In a pilot study, we quantified walking and stair negotiation preoperatively and 3 months postoperatively for seven patients with RHA (mean age, 49 years), seven patients with standard THA (mean age, 52 years), and seven age-matched control subjects (mean age, 56 years). Although both treatment groups demonstrated trends toward functional recovery, the RHA group had greater improvements in hip extension and abduction moment indicating typical loading of the hip. Further investigation is needed to determine if differences persist long term or are clinically meaningful.