Reconstruction of Paprosky type III acetabular bone defects in revision hip arthroplasty by using a combination of cage and morselized allografts.

Abstract

The reconstruction of Paprosky type III bone defects remains a challenge. Although biological fixation materials are currently dominant, cage continues to play a role in resource-poor settings. The aims of this study are to report the long-term follow-up survivorship of the combination of cage and morselized allograft in Paprosky type III bone defects and evaluate allografts' incorporation. We retrospectively analyzed 208 patients with Paprosky type III acetabular bone defects who underwent revision with a combination of cage and morselized allografts between January 2007 and January 2019. In total, 43 patients were followed up, with an mean follow-up of 10.6 years. There were 19 Paprosky type IIIA bone defect patients and 24 Paprosky type IIIB bone defect patients; seven patients of the 24 also had pelvic discontinuity (PD). Clinical assessment included Harris Hip Score (HHS) and 12-Item Short-Form Health Survey questionnaire (SF-12). Radiological assessment included cage stability, survivorship<u>,</u> and allograft incorporation. There were two re-revisions, one at 5.1 years postoperatively, another at 13.6 years postoperatively. The calculated survival rate of cages was 97.7% at ten years (95% CI 84.6% to 99.7%) and 85.5% at 15 years (95% CI 42.6% to 97.1%), with clinical failure as the endpoint. The calculated survival rate of cages was 94.2% (95% CI 78.1% to 98.6%) at both ten years and 15 years, with radiological failure as the endpoint. Cage remained stable in 39 patients (90.7%), and the cage in two patients was classified as possibly loose at the last follow-up. Allografts of 40 cases (93%) incorporated fully. HHS and SF-12 showed significant improvement at the last follow-up compared to the preoperative value (p < 0.0<u>5</u>). The combination of cage and morselized allografts is an alternative option for acetabular revision with Paprosky type III bone defects, with a satisfactory ten-year clinical survivorship of 97.7% and radiological survivorship of 94.2%.