Abstract
BACKGROUD: Complex acetabular defects (Paprosky II and III) present a challenge in total hip arthroplasty (THA). We used a "cup-in-cup" (CiC) construct wherein a trabecular metal cup (TMC) was press-fit and a dual mobility cup (DMC) was cemented within it. We added a porous acetabular augment (cup-in-cup with augment; CiCA) or a cage (cup-cage-cup; CCC) when required. METHODS: We reviewed patients who underwent complex acetabular reconstruction at our center between January 2012 to December 2021, with 2 to 11 years of follow-up. We assessed radiological restoration of the center of rotation using digital templating software (TraumaCad), functional outcome using the Harris Hip Score (HHS) and Forgotten Joint Score, and evaluated survival of the construct over 2-11 years by examining reoperation rates for any reason. RESULTS: Among 1,532 THAs performed in 1,448 patients (578 revisions), a TMC was used for acetabular reconstruction in 82 patients: 55 CiC, 15 CiCA, and 12 CCC were done. Eleven hips had Paprosky type IIC, 52 had IIIA, and 19 had IIIB acetabular defects. The mean cup size used was 64.10 ± 4.68 mm, the mean change in vertical and medial offset from the opposite side was 5.27 ± 4.68 mm and -1.21 ± 5.33 mm, respectively. The HHS improved from 49.01 ± 7.10 to 82.45 ± 6.66 at a mean follow-up of 54.7 months. Three-year survival was 96%, and 86% of the constructs survived at the latest follow-up. CONCLUSIONS: The TMC construct is a good option for Paprosky type II and III acetabular defects. Cementing a DMC restored optimal hip biomechanics. Our study provides robust data supporting its selection as the standard of care for addressing complex acetabular defects of all causes.