Biomedical Engineering in Surgical Repair of Osteonecrosis: the Role of Imaging Technology

Abstract

We fabricated biomimetic biphasic calcium phosphate (BCP) for tissue engineering in repair of avascular necrosis (AVN) or osteonecrosis (ON) and observed its outcome of reconstructiion in ON femoral head of dogs. Firstly, BCP ceramic scaffolds were fabricated with three-dimensional (3D) gel-lamination technique according to the two-dimensional (2D) images of trabecular structure of dog femoral head. Then, the 3D structure of the scaffolds was scanned and reconstructed using micro-CT for characterization of 3D patterns of its material structure related to trabecular parameters, including bone volume fraction (BVF-BV/TV), bone surface/bone volume (BS/BV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular spacing (Tb.Sp), structure model index (SMI), and trabecular pattern factor (Tb.Pf). After coatingmarrowstromal cells (MSCs) as seed cells onto biomimetic porous BCP constructed in vitro, the tissue-engineered bones were implanted into the bony defects of dog femoral head through trap-door procedure for 30 weeks. The femoral heads in control group were compacted with autograft bone chips for comparison. Results showed similar micro-CT data between control samples and experimental group implanted with BCP scaffolds, except that a more plate-like “trabecular” was pattern found in BCP scaffolds. Thirty weeks after operation, the contour and integrity of the femoral heads were basically maintained and the BCP scaffold showed trabecular bone formation and integration. On the other hand, the femoral heads in control group collapsed and presented osteoarthritic changes. These findings suggested that the biomimetic porous BCP scaffolds developed for this study coated with MSCs might be an effective approach in repair of the bony defect in ON of the femoral head.