Abstract
Introduction
Dislocation is a major cause of Total Hip Arthroplasty (THA) early failure and is highly influenced by surgical approach and component positioning. Robotic assisted arthroplasty has been developed to improve component positioning and therefore reduce post-operative complications.
The purpose of this study was to assess dislocation rate in robotic total hip arthroplasty performed with three different surgical approaches.
Methods
All patients undergoing Robotic Arm-Assisted THA at three centers between 2014 and 2019 were included for assessment. After exclusion, 1059 patients were considered; an anterior approach was performed in 323 patients (Center 2), lateral approach in 394 patients (Center 1 and Center 2) and posterior approach in 394 patients (Center 1 and Center 3).
Episodes of THA dislocation at 6 months of follow up were recorded. Stem anteversion, Cup anteversion, Cup inclination and Combined Anteversion were collected with the use of the integrated navigation system.
Cumulative incidence (CI), incidence rate (IR) and risk ratio (RR) were calculated with a confidence interval of 95%.
Results
Three cases of dislocation (2 posterior approach, 1 anterior approach) were recorded, with a dislocation rate of 0.28% and an IR of 0.14%.
Placement of cup in Lewinnek safe zone rate was 82.2% for posterior approach, 82.0% for lateral approach and 95.4% for anterior approach.
Placement in the Combined Version safe zone rate was 98.0% for posterior approach, 73.0% for lateral approach and 47.1% for anterior approach.
Despite the difference, dislocation IR was 0.30% for anterior approach, 0.34% for posterior approach and 0% for lateral approach.
Conclusion
Robotic assisted technique is associated with low dislocation risk, especially in posterior approach. The Combined version technique appears to be a reliable way to reduce dislocation risk in the posterior lateral approach, but does not appear to be essential for lateral and anterior approaches.
