Unilateral hindpaw amputation causes bilateral articular cartilage remodeling of the rat hip joint

Pathomechanics and classification of cartilage lesions, facilitation of repair

Joint forces have a high potential to promote degenerative changes in articular cartilage. Researchers have not yet developed a material that simulates natural articular cartilage, and replacement procedures have finite lives. In all patients, regardless of diagnostic category, the impact of rehabilitative procedures on the integrity and health of articular cartilage should be a consideration. In this paper, I will review why articular cartilage breaks down, how cartilage lesions are classified in vitro and in vivo, as well as cartilage's capacity for repair and repair enhancement. The primary focus will be on processes and procedures that impact physical therapy. Review sources included common computer-based search instruments and literature in all languages. This research showed that most studies have been conducted on animals, which differ in important respects from humans. Such studies, however, provide guidelines for physical therapists. Unloading and overloading are detrimental to articular cartilage. Research indicates value in controlled, progressive regimes that alternate load and non-load conditions.

Effects of continuous distraction on cartilage in a moving joint: an investigation on adult rabbits

An animal model, using distraction force on adult rabbits, was developed to study the effects of nonweight-bearing on articular cartilage in a moving joint. Histologic evaluation was used to compare the morphology of chondrocytes, safranin O intensity, cartilage thickness, and structural changes between the test and contralateral joints. At 3 and 6 weeks, the chondrocytes in superficial and intermediate zones were round, with an increase in cellular volume density and mean cell volume and with less metachromasia; the safranin O intensity and cartilage thickness were the same as in the controls. In cartilage of the 9-week group, mean cell volume decreased with cell cloning in the superficial zone, while numerical density increased and mean matrix volume per cell decreased in the superficial and intermediate zones. The cartilage, with a 34% reduction in thickness and a 53-72% decrease in safranin O intensity from the superficial to the deep zone, had superficial fibrotic proliferation, surface erosion or depression, and tidemark irregularity. Continuous distraction in a moving joint caused morphological changes in chondrocytes prior to degeneration of cartilage. These results support the hypothesis that the forces perceived by cells may dictate their shape and then stimulate alterations in cellular biochemistry and matrix metabolism.