Abstract
Introduction
Lewinnek et al described a safe zone of acetabular component placement in Total Hip Arthroplasty (THA) to reduce complications. Callanan et al proposed a modified safe zone with a reduced range of acetabular inclination of 30–45 degrees to eliminate the steeper or more inclinated cups 2. This study compares the accuracy of cup placement in the safe zones described by Lewinnek et al and Callanan et al, leg length discrepancy (LLD) and global offset (GO) measurement in THA using five different surgical techniques performed by six different surgeons.
Methods
Between June 2008 and April 2014, 2330 THRs were performed by six different surgeons. Post-operative radiographic images were retrospectively reviewed and measured using TraumaCad® software to determine cup placement, LLD, and GOD.
Results
One thousand, nine hundred-eighty patients met the inclusion and exclusion criteria. Ninety-three (4.69%) patients underwent robotic-assisted THA anterior approach, 135 (6.8%) had robotic-assisted THA posterior approach, 942 (47.5%) patients underwent fluoroscopic guided THA anterior approach, 708 (35.7%) had THA without guidance using posterior approach, 43 (2.1%) patients underwent navigation-guided anterior approach and 59 (2.9%) patients underwent radiographic-guided posterior approach THAs. Robotic guidance groups had a significantly greater percentage of hips in the Lewinnek's and Callanan's safe zone (p < 0.005). Between robotic guidance groups, the group with posterior approach has more cups placed in the Lewinnek's and Callanan's safe zone (p < 0.005). The frequency of hips within the Lewinnek's safe zone was significantly greater in the navigation guided group, compared to the other groups except robotic guided (p < 0.05). Sixty-four (3.2%) of our cases were with LLD greater than or equal to 10mm, five of those cases were (8.5%) in the group treated with x-ray guidance. (p < 0.05). The mean GOD for the overall cohort was 4.0mm ± 0.4mm (p < 0.0001). Mean ages of patients in the treatment groups were significantly different (p < 0.0001).
Conclusion
Robotic assisted surgery was more consistent than the other techniques in placing the acetabular cup into the Lewinnek and Callanan safe zone. The use of robotic assistance in hip arthroplasty surgery is more accurate fulfilling the goals needed to actual hip arthroplasty. Long term follow-up is required to determine clinical impact of increased accuracy.
