Statistical shape modeling of the large acetabular defect in hip revision surgery

Area of Science:

• Orthopedic surgery
• Medical imaging
• Biomechanical engineering

Background:

• Assessing 3D bony defects is crucial for hip reconstruction surgery.
• Contralateral mirroring is a common method for measuring hip center of rotation (CoR), but may be unreliable with diseased or replaced contralateral hips.
• Statistical Shape Models (SSMs) offer a potential solution for reconstructing patient anatomy.

Purpose of the Study:

• To evaluate the efficacy of SSMs in reconstructing absent bony landmarks for hip revision surgery.
• To compare the accuracy of SSM-derived hip center of rotation (CoR) with diseased hips, surgical plans, and contralateral healthy hips.

Main Methods:

• A retrospective cohort study of 38 patients with Paprosky type IIIB defects.
• An SSM was developed from 50 healthy pelvises to virtually reconstruct native pelvic morphology.
• Outcome measures included differences in CoR between SSM, diseased hip, surgical plan, and contralateral hip.

Main Results:

• Median differences in CoR were 31.17 mm (SSM vs. diseased), 8.53 mm (SSM vs. plan), and 7.84 mm (SSM vs. contralateral).
• No significant statistical difference was found between SSM-derived CoR and surgical plan or contralateral CoR (p > 0.05).

Conclusions:

• SSMs can reliably reconstruct absent bony landmarks in patients with severe acetabular defects.
• This technique aids surgical planning for hip reconstruction and implant design, even with significant bone loss.
• SSMs provide a valuable tool when contralateral mirroring is not feasible.