Abstract
Aims: Fourier transform infrared imaging (FTIRI) is a new quantitative imaging technique for direct visualization of chemical constituents. Our goal was to investigate the suitability of FTIRI to characterize material properties of articular cartilage (AC) and its ability to indirectly determine biomechanical characteristics of AC. Methods: Cylindrical AC samples (dia.=3.7 mm, n=6) with different stages of osteoarthrosis (OA) were prepared from bovine patellae and mechanical properties of AC were determined with a highresolution material testing device to determine Youngñs modulus (stiffness) at equilibrium (E). After biomechanical testing, one piece of the sample was processed for the histological grading of OA and the other piece was processed for FTIRI. Measurements were conducted from air-dried cryosections. Degree of cartilage degeneration was characterized by the integrated area of amide I and II absorbance. Water content of the specimen was determined from the remaining tissue by measuring the wet and dry weight of the sample. Results: Histological Mankinñs grades of the samples ranged from 0 to 7 indicating that cartilage samples showed only mild to moderate OA. FTIRI absorption showed high correlations with histological grading (r=−0.928) and water content (r=−0.980). Also, average infrared absorption of AC correlated highly linearly with E (r=0.826). Conclusions: Present results show that FTIRI offers a new tool for structural evaluation of AC quality and chemical composition. FTIR correlated well with the histological and biomechanical þndings. Technique offers a new approach to optically determine cartilage constituents. In addition to in vitro research FTIR can be coupled to arthroscopic þber optic probe in order to diagnose cartilage structure and composition in vivo.
Theses abstracts were prepared by Professor Dr. Frantz Langlais. Correspondence should be addressed to him at EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
