Bone block augmentation from the iliac crest for treatment of deep osteochondral defects of the knee resembles biomechanical properties of the subchondral bone

Purpose Bone block augmentation from the iliac crest can be used for reconstruction of the osteochondral unit to restore the underlying subchondral bone upon restoration of the cartilaginous layer via matrix-induced chondrocyte transplantation. To critically understand the successful restoration of the defect, biomechanical and histological analysis of the implanted bone blocks is required. The aim of the study was to analyse the ability of the bone block technique to restore huge bone defects by mimicking the physiological subchondral zone. Methods The experiments were performed using lateral femoral condyles and iliac crest bone grafts from the same cadavers ( n = 6) preserved using the Thiel method. CT scans were made to evaluate bone pathology. Bone mineral density of all specimens was evaluated in the femoral head prior to testing. A series of tests were conducted for each pair of specimens. A static compression test was performed using an electro dynamic testing machine with maximal strength and failure behavior analyzed. Biomechanical tests were performed in the medial–lateral direction for iliac crest and for femoral condyles with and without removal of the cartilage layer. Histological analysis was performed on decalcified specimens for comparison of the condyle at lesion site and the graft. Results No significant difference in failure load could be found for iliac crest (53.3–180.5 N) and femoral condyle samples upon cartilage removal (38.5–175.1 N) (n.s.). The femoral condyles with an intact cartilage layer showed significantly higher loads (118.3–260.4N) compared to the other groups indicating that native or regenerated cartilage can further increase the failure load ( p