Accuracy of an image-free handheld hip navigation device for total hip arthroplasty in a lateral decubitus position

Abstract Background: Portable navigation systems have been developed for use in total hip arthroplasty (THA) in recent years. The purpose of this study was to investigate the accuracy of cup insertion in primary THA using an image-free handheld navigation device in the lateral decubitus position. Methods: This retrospective study included 68 consecutive cementless THAs performed using an image-free handheld navigation device and 68 consecutive THAs performed without a navigation system as historical controls. All cases underwent THAs in a lateral decubitus position. Postoperative cup radiographic inclination and radiographic anteversion were assessed, and the accuracy of cup insertion was compared between the two groups. Navigation error was also assessed. Results: The mean absolute errors of the postoperative measured inclination from the target inclination were 3.9° ± 2.2° in the navigation group and 8.5° ± 6.9° in the control group (p<0.001). The mean absolute errors of anteversion were 4.8° ± 3.5° in the navigation group and 11.4° ± 6.6° in the control group (p<0.001). The percentage of cups inside Lewinnek’s safe zone was 94% in the navigation group and 37% in the control group (p<0.001). The mean absolute values of navigation error were 3.1° ± 2.1° in inclination and 4.2° ± 2.8° in anteversion. No factors affected the navigation errors. Conclusions: Use of an image-free handheld navigation device can improve the accuracy of cup insertion compared with conventional manual technique in THA in the lateral decubitus position.