Arthroscopic microscopy of articular cartilage using optical coherence tomography

Background: Optical coherence tomography is an echograph of infrared light that can yield microscopic cross-sectional images of articular cartilage without removing or damaging the tissue. Hypothesis: To determine whether optical coherence tomography images of human cartilage can be acquired arthroscopically and whether the resulting images have high correlation with histopathology. Methods: Optical coherence tomography was configured into an arthroscope and used to image 2 human cadaver knees and 45 cores harvested from 9 osteoarthritic knees. The imaged cartilage was then processed for histological analysis. Optical coherence tomography images and histology were graded using a modified Mankin structural score. Agreement was determined using weighted kappa statistics. Morphometric analysis performed on optical coherence tomography images was correlated with histomorphometric analysis using linear regression. Results: Imaging of the medial and lateral femoral condyles and trochlea was readily accomplished using the optical coherence tomography arthroscope. Modified Mankin surface scores for specimens with the earliest structural changes (grades 0-3) had high agreement with scores assigned to histology (kappa = 0.87). Fibrillation indices calculated from optical coherence tomography had near-perfect correlation to that of histology (R = 0.98). Clinical Relevance: Arthroscopic optical coherence tomography may be clinically useful for early detection of articular cartilage injury and nondestructive assessment of articular cartilage repair.