The effects of defect size, orientation, and location on subchondral bone contact in oval-shaped experimental articular cartilage defects in a bovine knee model.

Purpose: Chondral defects of the knee may lead to pain and disability, often requiring surgical intervention. The purpose of this study was to identify how size, location, and orientation influences subchondral bone contact within oval-shaped chondral defects.

Methods: Full-thickness defects were created in twelve bovine knees. Defect orientation was randomized between coronal and sagittal planes on both the medial and lateral femoral condyles (MFC and LFC). In extension, knees were statically loaded to 1,000 N. Area measurements were recorded using Tekscan sensors and I-Scan software. A MATLAB program computed defect area and the area within the defect demonstrating subchondral bone contact.

Results: Defect area, location, and orientation each had a significant effect on subchondral bone contact (p < 0.001), and significant interactions were found between defect area and both location and orientation. The size threshold (cm(2)) at which significant contact occurred on the subchondral bone within the defect was smallest for LFC/coronal defects (0.73 cm(2)), then LFC/sagittal (1.14 cm(2)), then MFC/coronal (1.61 cm(2)), and then MFC/sagittal (no threshold reached).

Conclusions: Intra-articular location and orientation of a femoral condyle chondral defect, in addition to area, significantly influence femoral subchondral bone contact within the defect and the threshold at which subchondral bone contact occurs within the defect. The parameters of defect location and shape orientation supplement current surgical algorithms to manage knee articular cartilage surgery. This may indicate different cartilage restorative procedures based on the effect on the subchondral bone from the defect geometry itself and the selected cartilage surgery.