The purpose of this study was to conduct a prospective clinical trial to investigate the accuracy of an MRI-based patient-specific acetabular instrument guide during THA.
We conducted a prospective consecutive review of 14 hips in 14 patients who underwent primary THA with a posterolateral approach between September 2016 and February 2018. All preoperative planning and postoperative evaluations were completed on CT-based templating software. A pelvic MRI was taken to create a patient-specific surgical instrument guide. In order to assess the effect of increased experience on accuracy, we divided the cases into two groups according to when surgery was performed and investigated the absolute error in the acetabular component angle between preoperative planning and the postoperative state for each of the groups.
We did not experience postoperative complications such as implant early dislocation in any of the cases. The absolute errors of acetabular implant angle using the patient-specific instrument guide were 3.7° ± 2.2° inclination and 4.5° ± 3.9° anteversion. The absolute error of the initial group was 4.7° ± 2.1° inclination and 6.1° ± 4.0° anteversion; for the later group, it was 2.8° ± 1.8° inclination and 3.2° ± 2.9° anteversion. There was a significant difference in the absolute error of acetabular implant placement between the initial group and the later group.
We believe this study shows that MRI-based patient-specific instrumentation may be a useful alternative to surgical tracking during THA once the slight learning curve has been overcome.