new approach for Paprosky 3 acetabular defects with patient matched 3D printed implants based on bone quality assessment

Background: Reconstruction of Paprosky type 3 acetabular defects and pelvic dissociation remains a significant challenge in revision hip arthroplasty. Conventional techniques, including structural allografts and reconstruction cages, often yield inconsistent results due to inadequate primary stability and limited biological ingrowth.

Objective: This study describes the preoperative planning, surgical technique, and preliminary clinical outcomes of a patient-matched, 3D-printed monobloc trabecular titanium acetabular revision system.

Key Points: The system utilizes CT-based software to subtract existing hardware, assess bone quality via Hounsfield units, and determine the native center of rotation. A custom implant with integrated flanges and pre-planned screw trajectories is manufactured via 3D printing. In a cohort of 32 patients (median age 68 years) with a minimum 2-year follow-up, the Oxford Hip Score improved from a preoperative mean of 51 to 29 postoperatively. Visual analog scale scores for activity decreased from 89 to 11. Radiographic analysis confirmed no implant migration or construct breakage, although screw loosening occurred in three cases. Complications included three re-operations for delayed wound healing (9%), one deep infection, and one dislocation. The surgical technique emphasizes a posterolateral approach with extensive exposure of the ilium, ischium, and pubic bone to ensure precise implant seating.

Conclusion: Patient-specific 3D-printed titanium implants provide a viable solution for complex acetabular reconstructions. The technology allows for accurate restoration of hip mechanics and stable primary fixation through bone-quality-guided screw placement, resulting in favorable short-term clinical and radiological outcomes.