Functional assessment of joint use in experimental inflammatory murine arthritis

A select group of cartilage proteoglycans (fetal human, porcine, and canine articular cartilages and human osteophytes, all depleted of chondroitin sulfate) produces progressive polyarthritis and spondylitis in BALB/c mice. The development of the disease in this murine strain is dependent on the expression of both cell-mediated and humoral immunities to host mouse cartilage proteoglycan. Autoantibodies have been detected in sera of arthritis animals from the fifth to sixth week after immunization, and their appearance precedes the development of the first clinical symptoms by a few days in animals with passively transferred arthritis. In this preliminary experiment, we describe several functional tests and gait analyses in normal mice, in acutely and chronically arthritic mice, and in randomly selected mice with proteoglycan-induced and collagen-induced arthritis. The procedures revealed that changes in joint use and gait could predate by weeks the appearance of the first clinical symptoms (joint swelling, redness, and joint stiffness) of arthritis in mice. Moreover, abnormalities measured by functional tests, such as strength of grip and maintenance of posture on sandpaper, wood, or vinyl surfaces at three different tilt angles (30, 45, and 60 degrees), and gait analysis preceded the appearance of autoantibodies in sera of immunized animals; this indicates that such measurements could provide a noninvasive and simple method to assess joint function accurately during the development of arthritis.