Accuracy of two different imageless navigation systems for leg length and global offset change in total hip arthroplasty: A comparison using two-dimensional radiographic and three-dimensional CT-based evaluation.

PURPOSE: This study aimed to evaluate the accuracy of two imageless navigation systems for restoring leg length change (LLC) and global offset change (GOC) in total hip arthroplasty (THA) using two-dimensional (2D) radiographic and three-dimensional computed tomography (3D CT)-based assessment methods.

METHODS

Patients undergoing primary cementless THA were divided into two groups based on the imageless navigation system used: a large-console group (n = 120) and a portable handheld group (n = 83). Intraoperative navigation measurements of the LLC and GOC were compared with values derived from preoperative and postoperative assessments, and absolute measurement errors were calculated. Accuracy was evaluated using 2D radiographic and 3D CT-based measurements. Between-system differences and discrepancies between 2 and 3D assessment methods were analyzed.

RESULTS

Absolute LLC error in the large-console group was 2.7 ± 3.3 mm on 2D radiographic evaluation and 2.5 ± 3.3 mm on 3D CT-based evaluation, compared with 2.9 ± 2.7 mm and 3.0 ± 2.8 mm, respectively, in the portable handheld group. LLC error was significantly lower in the large-console group on 3D evaluation (p = 0.004). Absolute GOC error did not differ significantly between groups. No differences were observed between 2 and 3D evaluations for LLC, whereas most GOC-related parameters differed significantly between methods.

CONCLUSION

Imageless navigation systems achieved favorable accuracy for LLC and GOC in THA. While radiographic assessment is sufficient for evaluating leg length, 3D CT-based evaluation provides a more consistent and less position-dependent assessment of global offset.