In Vitro Evaluation of a Device to Assess Acetabular Cup Position by Sagittal Plane Radiography

Abstract

Objectives

The purpose of this study was to compare the calculated angle of lateral opening (ALO) and open-face version obtained using an acetabular cup position assessment device (CPAD) to the known ALO and open-face version of an acetabular component. The null hypothesis was that there would be no significant differences between the ALO and open-face versions using the CPAD compared with the known values.

Methods

Radiographic images simulating a sagittal plane pelvis were obtained with a BFX™ acetabular component containing a CPAD mounted on a plexiglass jig with a dual-plane inclinometer. Images were obtained at an open-face version of 0 degrees with ALO at 30, 40, 45, 50, and 60 degrees, repeated in triplicate, and were randomized. Measurements of the CPAD bars were used to calculate the open-face version, and ALO measurements were compared using a paired t-test with a p-value set at p < 0.05. Agreement was assessed with a Lin's Concordance Correlation Coefficient.

Results

The calculated ALO was not significantly different from the known ALO (p = 0.608) and showed near-perfect correlation of the ALO with a Lin's Concordance Correlation Coefficient (R _c value) of 0.994. The calculated open-face version was significantly different from the known version.

Conclusion

The results demonstrate that the CPAD is an accurate method to determine ALO in a simulated sagittal plane pelvis radiographic view.

Keywords

total hip arthroplasty - acetabular component - angle of lateral opening - cup position assessment device - version

Note

This study was presented in part at the American College of Veterinary Surgeons Surgery Summit in Phoenix, AZ, on October 25, 2018.

Authors' Contribution

R.L. developed the concept. R.L. and M.P.K. contributed to the design of the CPAD. All authors contributed to the study design. W.M.K. and R.L. contributed to data acquisition. W.M.K. and M.P.K. contributed to data analysis and interpretation. All authors drafted and revised the manuscript and approved the submission.

Publication History

Received: 19 February 2025

Accepted: 09 July 2025

Article published online:
22 July 2025

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