Preoperative Three-Dimensional Planning Using Computed Tomography Improves Screw Placement in Patients Undergoing Acetabular Revision Surgery

Background

Stable fixation of joint replacement implants is essential to achieve osseointegration in uncemented implants. In acetabular revisions, screws often need to be utilized in quadrants other than the historically so-called “safe” zones to attain sufficient stability. The primary aim of this study was to determine whether preoperative three-dimensional (3D) planning for acetabular revision surgery influences screw length, specifically in the superior pubic ramus (SPR).

Methods

Between March 2017 and December 2021, 20 patients underwent preoperative two-dimensional (2D) planning (2D group), and 30 patients underwent 3D planning following the implementation of a new 3D planning software into clinical practice in September 2019 (3D group). Two observers, blinded to the groups, measured the total screw length, screw penetration depth, and cup position on available postoperative computed tomography examinations. For statistical comparisons, the mean measurement from the 2 observers was used.

Results

The median total screw lengths in the SPR were 16 mm in the 2D group and 25 mm in the 3D group (P = .004) and 40.5 mm compared with 50.5 mm in the ilium (P = .019). Median screw penetration depths in the SPR were 0 mm in the 2D group and 1.25 mm in the 3D group (P = .049).

Conclusion

Longer screws were used in the SPR and ilium when preoperative 3D planning was conducted. Due to the study design, we were not able to evaluate whether longer screws lead to better fixation. Further studies are needed to elucidate this question.