Measurements of ligament and cartilage optical properties at 35mm, 365nm and in the visible range [440-800nm]. Marie-Anne Descalle*, Steve L. Jacques**, Scott A. Prahl**, Timothy J. Laing***, William R. Martin*. * Nuclear Engineering and Radiological Sciences Dept., University of Michigan, 2355 Bonisteel Blvd, North Campus Ann Arbor, MI 48109-2104, USA phone: (313) 936-0123 FAX: (313) 763-4540 ** Oregon Medical Laser Center, Providence St. Vincent Medical Center 9205 SW Barnes Rd Portland, OR 97225, USA phone: (503) 216-4092 FAX: (503) 216-2422 ***Jnternal medicine! Div. of Rheumatology, Taubman Center, University of Michigan, 918 Taubman center, box 0358, 1500 East Medical Drive Ann Arbor, MI 48109-0358, USA phone: (313) 936-5560 FAX: (313) 763-1253 Abstract To further evaluate the potential for intra-articular phototherapy, the optical properties of normal porcine ligament and cartilage were determined in vitro. The diffuse reflectance, Rd, was measured with an inte- grating sphere at 351, 365nm and in the range 440-800nm. The lateral spread of light introduced by a 400mm optical fiber was measured and analyzed to yield the optical penetration depth, ö. The two mea- surements, Rd and ö yielded the absorption coefficient ha [cnr'], and the reduced scattering i'=p(l-g) [cm'] at 351, 365nm and in the range 440-800nm. keywords: optical properties, diffuse reflectance, in vitro, cartilage, ligamentf 1. Introduction Rheumatoid arthritis is a common chronic inflammatory disorder involving the synovium (synovial membrane) ofjoints. It is characterized by the presence of three pathobiological phenomena: inflammation, abnormal cellular and humoral immune response and synovial hyperplasia. Over time, patients are disabled due to a progressive joint destruction. Current treatments focus either on systemic immune suppression due to the autoimmune nature of the disease, or on local surgical synovectomy which involves local ablation of the inflamed synovial tissue. However, because these available therapies are only partially successful, new strategies are being investigated. Local therapy directed at the synovium offers the advantage of freedom of systemic side effects and the potential for synergy with systemic treatments, despite the limitation that multiple joints cannot be 280 SPIE Vol. 3195. 0277-786X1981$10.0Q Downloaded from SPIE Digital Library on 29 Aug 2010 to 137.53.1.30. Terms of Use: http://spiedl.org/terms