Impaction bone grafting for segmental acetabular defects: a biomechanical study

Abstract

Introduction Implant loosening is the most common indication for revision after total hip arthroplasty and is associated with progressive bone destruction. Contained defects can be treated with impaction bone grafting (IBG). Segmental defects are successfully restored with metal augmentation. Considering the increasing number of hip arthroplasty cases in young patients, it would appear sensible to reconstruct the bone stock for future revisions by biological bone defect reduction. The data on the treatment of segmental defects with IBG without additional stabilization are lacking. Materials and methods Paprosky type IIB defects were milled into 15 porcine hemipelves with segmental defect angles of 40°, 80° and 120°. Contained defects without segmental defects (Paprosky type I) and acetabula without defects served as controls. After IBG, a cemented polyethylene cup (PE) was implanted in each case. Cup migration, rotational stiffness and maximum rupture torque were determined under physiological loading conditions after 2500 cycles. Results Compared with the control without defects, IBG cups showed an asymptotic migration of 0.26 mm ± 0.11 mm on average. This seating was not dependent on the size of the defect. The maximum rupture moment was also not dependent on the defect size for cups after IBG. In contrast, the torsional stiffness of cups with an 120° segmental defect angle was significantly lower than in the control group without defects. All other defects did not differ in torsional stiffness from the control without defects. Conclusions IBG did not show inferior biomechanical properties in segmental type IIB defect angles up to 80°, compared to cups without defects.

Impaction Bone Grafting with Low Dose Irradiated Freeze‐Dried Allograft Bone for Acetabular Reconstruction

“…11 IBG is a well-established surgical technique pioneered by the Nijmegen 12 and Exeter 13 Group; a technique that can restore deficient acetabular bone stock and recreate anatomic center of rotation with a standard size acetabular socket even in Paprosky 3 and AAOS type III defects with favorable survivorships. 9,10,[14][15][16] Due to aseptic loosening, the survivorship of acetabular components in IBG ranged from 100% at 10 years 17 to 85% after 20 years and 77% after 25 years. 18 Only by restoring bone stock, future revisions and re-revisions can be undertaken with ease.…”