Evaluation of Single-Impact-Induced Cartilage Degeneration by Optical Coherence Tomography

Abstract

Posttraumatic osteoarthritis constitutes a major cause of disability in our increasingly elderly population. Unfortunately, current imaging modalities are too insensitive to detect early degenerative changes of this disease. Optical coherence tomography (OCT) is a promising nondestructive imaging technique that allows surface and subsurface imaging of cartilage, at near-histological resolution, and is principally applicable in vivo during arthroscopy. Thirty-four macroscopically normal human cartilage-bone samples obtained from total joint replacements were subjected to standardized single impacts in vitro (range: 0.25 J to 0.98 J). 3D OCT measurements of impact area and adjacent tissue were performed prior to impaction, directly after impaction, and 1, 4, and 8 days later. OCT images were assessed qualitatively (DJD classification) and quantitatively using established parameters (OII, Optical Irregularity Index; OHI, Optical Homogeneity Index; OAI, Optical Attenuation Index) and compared to corresponding histological sections. While OAI and OHI scores were not significantly changed in response to low- or moderate-impact energies, high-impact energies significantly increased mean DJD grades (histology and OCT) and OII scores. In conclusion, OCT-based parameterization and quantification are able to reliably detect loss of cartilage surface integrity after high-energy traumatic insults and hold potential to be used for clinical screening of early osteoarthritis.

Comparison between in vitro and in vivo cartilage overloading studies based on a systematic literature review

“…Fissures proceed to increasing depths into the cartilage matrix following the arcade‐like architecture of the collagen network, that is, originally parallel to the articular surface and then transitioning into the radial orientation, until finally the fissures run along the calcified boundary and cartilage delamination occurs . The probability and severity of surface fissuring following trauma generally increases with higher impact energy, applied stress, stress rate, frequency of dynamic loading, loading duration, and a period of prolonged creep prior to overloading. From a certain impact threshold, in this case an impact energy of 0.25 J imposed on 5 mm diameter cartilage explants, it has even been observed that there was damage to the subchondral bone without macroscopic damage to the cartilage .…”

Delivery of Agents Into Articular Cartilage With Electric Spark-Induced Sound Waves

“…Histology and analysis of proteoglycan content are standard methods in detecting early stages of post-traumatic AC degeneration in vitro [38,39]. These approaches showed no evidence of structural changes induced by the treatment, for instance, proteoglycan loss, collagen network degradation, and surface irregularity formation (i.e., erosion or fissuring).…”

Polarization-sensitive optical coherence tomography-based imaging, parameterization, and quantification of human cartilage degeneration

“…Structural parameters obtained by the former included surface irregularity [optical irregularity index (OII)], tissue homogeneity [optical homogeneity index (OHI)], and signal penetration [optical attenuation index (OAI)] as described before. 12,14,17,36 Briefly, Savitzky-Golay filtering was applied to surface data matrices to obtain smoothed surface topographies. OII as a measure of surface integrity was defined as the standard deviation (SD) between the actual and the smoothed surface topography and calculated in absolute terms.…”