Bone remodeling after revision total hip arthroplasty for large acetabular defects

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Radiology

Background:

• Large acetabular bone defects present significant challenges in hip revision surgery.
• Evaluating new surgical reconstruction technologies requires thorough clinical assessment.
• Understanding bone remodeling post-acetabular reconstruction is crucial for improving patient outcomes.

Purpose of the Study:

• To characterize pelvic shape changes after acetabular reconstruction using sequential CT scans.
• To identify specific pelvic regions most susceptible to bone remodeling.
• To analyze bone remodeling in patients with Paprosky IIIB acetabular defects treated with custom 3D-printed implants.

Main Methods:

• Sequential CT scans from 24 patients (Paprosky IIIB defects) were analyzed immediately and 1-year postoperatively.
• 3D pelvic models were co-registered globally, then focusing on the innominate bone and ilium.
• Relative movements of the ilium, ischium, and pubis were assessed using co-registration metrics and visual inspection.

Main Results:

• No significant bone remodeling was observed in 58% (14/24) of patients.
• Innominate bone co-registration revealed remodeling in 21% (5/24) of cases.
• Global co-registration showed remodeling in an additional 21% (5/24), suggesting sacroiliac joint involvement. Remodeling was most pronounced in the pubis and ischium.

Conclusions:

• Bone remodeling can occur in approximately 21% of complex Paprosky type IIIB acetabular defects following reconstruction.
• The pubis and ischium are the most susceptible pelvic regions to shape changes.
• Surgeons and engineers must consider potential bone remodeling when monitoring acetabular implant migration.