Open-face plane orientation of a BioMedtrix biologic fixation acetabular cup can be accurately determined from a lateral radiograph.

Lateral radiographs can accurately determine BFX acetabular cup orientation within approximately 5 degrees, aiding postoperative assessment.

This study developed and validated a geometric trigonometry-based method to calculate the open-face plane orientation of a BioMedtrix biologic fixation (BFX) acetabular cup using measurements obtained from a standard lateral radiograph. The authors derived calculation formulas using geometric arguments and trigonometry, then validated the method through 52 in vitro trials using a plastic pelvis model implanted with a BFX acetabular cup in varying orientations. For each trial, the cup orientation was calculated from lateral radiographic measurements and compared against direct physical measurement of the cup's open-face plane. The derived method demonstrated high repeatability and reproducibility, with intra- and interobserver intraclass correlation coefficients exceeding 0.94. The direct measurement method also showed high reproducibility, with interobserver intraclass correlation coefficients above 0.98. The mean absolute angular difference between calculated and directly measured orientation vectors was 2.8 ± 1.3°, with 95% of trials falling within 4.7° of the directly measured value. These results indicate that the calculated orientation closely agrees with actual cup positioning. Clinically, this method provides surgeons with a non-invasive, radiograph-based tool to assess BFX acetabular cup positioning postoperatively. Accurate knowledge of cup orientation can guide decisions regarding cup revision, facilitate identification of complications related to cup malposition such as impingement or luxation, and enable surgeons to evaluate and improve their cup placement technique over time.

This summary was distilled by AI and may occasionally misinterpret data. Confirm critical details with the primary literature before clinical application.