Comparison between the accuracy of conventional and portable computed tomography-based navigation systems in total hip arthroplasty

BACKGROUND: Although conventional computed tomography (CT)-based navigation provides excellent placement accuracy and clinical outcomes, whether recently introduced portable systems can achieve comparable results remains unclear. This study aimed to evaluate the placement accuracy and surgical outcomes of portable CT-based navigation systems. METHODS: This study assessed 56 hips of patients that underwent total hip arthroplasty (THA) using portable CT-based navigation. Using propensity score matching based on age, sex, and body mass index, we identified 51 hips treated with portable CT-based navigation (portable CTN group) and 51 hips with conventional CT-based navigation (CTN group). The evaluation parameters included cup orientation accuracy, cup positioning, operative time, blood loss, preoperative and postoperative Japanese Orthopaedic Association scores, and complications. RESULTS: Regarding accuracy error, the portable CTN (radiographic inclination [RI]: 2.8 ± 2.8°, radiographic anteversion [RA]: 3.8 ± 3.2°) and CTN groups (RI: 2.7 ± 1.9°, RA: 3.0 ± 2.1°) did not significantly differ. For navigation error, the portable CTN group (RI: 3.2 ± 3.2°, RA: 3.5 ± 3.1°) had significantly inferior results to the CTN group (RI: 2.2 ± 1.7°, RA: 2.3 ± 1.7°) regarding anteversion. The portable CTN group demonstrated a significantly lower accuracy, as the proportion of hips with a navigation error of > 5° was 31.4% (16 hips), compared to 11.8% (6 hips) in the CTN group. For cup position, the horizontal position error in the portable CTN group was 3.1 ± 1.8 mm, significantly less accurate than the 2.3 ± 1.9 mm in the CTN group. No significant differences were observed in the clinical outcomes within the follow-up period of one year. CONCLUSION: Portable CT-based navigation was inferior to conventional CT-based navigation in terms of placement accuracy, including cup orientation and positioning. While clinical outcomes did not significantly differ at the one-year follow-up, this short-term follow-up limits conclusions on long-term clinical equivalence. Future advancements in portable CT-based navigation systems are required to improve their accuracy.