Accuracy of Component Positioning in 2330 Total Hip Arthroplasties: A Comparative Analysis by Surgical Technique and Mode of Guidance

Lewinnek et al described a safe zone of acetabular component placement in Total Hip Arthroplasty (THA) to reduce complications. This safe zone is between 10-30 degrees of version and 30-50 degrees of inclination 1 . Callanan et al. reports only 53% of acetabular cups were within Lewinnek’s Safe Zone of optimal cup placement (62% within the abduction safe zone, 79% within the version safe zone). 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 . Robotic assisted surgery has shown more accurate acetabular component placement in a single surgeon study. Domb et al saw 100% of acetabular components within the Lewinnek safe zone compared to 80% of manual cases. When using the Callanan modified safe zone 92% versus 62% when comparing robotic assisted results to manual cases 3 . 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.