Effect of anterior acetabular rim recession on radiographic parameters: an in vivo study

The purpose of this study was to validate additional radiographic parameters that detect changes within the acetabular cavity during acetabular rim trimming for pincer-type femoroacetabular impingement in an in vivo setting.

Patients who met the inclusion criteria and underwent arthroscopic acetabular rim trimming had their preoperative and postoperative anteroposterior radiographs measured. Intraoperatively, these patients had their labrums detached, acetabular walls trimmed by roughly 3 to 5 mm, and then labrums reattached. Radiographic measurements were subsequently obtained by use of the anterior rim angle (ARA), anterior wall angle (AWA), and anterior margin ratio (AMR).

Statistically significant changes were seen in the postoperative ARA, AWA, and AMR. Mean pre- and post-trimming changes were 83.8° and 87.9°, respectively, for the ARA; 38.8° and 35.8°, respectively, for the AWA; and 0.57 and 0.53, respectively, for the AMR. There were no postoperative complications. No patients had any instability events.

This study shows that significant changes in anterior acetabular anatomy can be evaluated radiographically in the in vivo setting for treatment of pincer-type femoroacetabular impingement. We saw a significant, consistent decrease in both the AWA and AMR and increase in the ARA. This research serves to guide surgeons with preoperative and intraoperative templating while providing the groundwork to investigate these radiographic parameters in an asymptomatic patient population.

These novel radiographic measurements can be used by hip arthroscopists to better characterize their surgical role in altering acetabular morphology. In addition, these measurements will be able to better describe acetabular anatomy.