Introduction: Robotic-assisted total hip arthroplasty (RA-THA) provides an alternative to fluoroscopic guidance, thus reducing radiation exposure for orthopaedic surgeons. This study was performed to assess the learning curve associated with the adoption of RA-THA using the direct anterior approach (DAA) with regard to surgical time, use of fluoroscopy, and implant placement. In addition, we compared complication rates and patient-reported outcome scores between both cohorts. A case report of an RA-THA is also presented.
Materials and methods: This was a retrospective, non-randomized evaluation of the learning curve by assessing surgical time on a consecutive series of 89 DAA cases performed by a single surgeon. There were 53 cases that had manual THA with fluoroscopy and 36 cases with RA-THA. All cases had an acetabular component placement target of 40° inclination and 20° anteversion. An independent reviewer blinded to surgical technique used the Widmer method to measure acetabular inclination and version. Patient demographics were similar for both groups.
Results: The mean surgical time for the manual fluoroscopic group was 88 ± 21 minutes and 101 ± 14 minutes for the RA-THA group. After 15 RA-THA cases, surgical time reached time neutral compared to the manual fluoroscopic group. The first 17 RA-THA cases utilized fluoroscopy to verify implant position until the surgeon became comfortable with the accuracy of the RA-THA system. After case 17, fluoroscopy was abandoned in all subsequent RA-THA cases. The mean radiation dose delivered to the surgical field was 5.61 ± 5.71 mGy. Manual THA with fluoroscopy resulted in a mean acetabular inclination of 41.3 ± 4.4° and a mean anteversion of 22.4 ± 3.0°. The RA-THA resulted in a mean acetabular inclination of 42.0 ± 4.2° and a mean anteversion of 22.3 ± 3.9°. There was no noted change in RA-THA placement accuracy after case 17, when fluoroscopy was eliminated from the surgical workflow. There were no statistical differences between the manual fluoroscopic and robotic-assisted groups with respect to complications and clinical PROM outcomes.
Conclusion: The DAA THA can be performed with RA-THA and achieve comparable acetabular placement without fluoroscopy. Surgical time was higher for the RA-THA group during the learning curve, but then decreased and was consistent with the manual fluoroscopic group after 15 cases.