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

Abstract

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.

No beneficial effects of joint distraction on early microscopical changes in osteoarthrotic knees

“…Application of an external fixator itself has been suspected to cause changes similar to OA (Hung et al 1997). Our results reveal that there is no significant effect of simple external fixation of the joints, and it can be used safely for fractures around osteoarthrotic joints.…”

“…Nonarticulated distraction worsened the results very significantly, while simple external fixation or articulated distraction had no statistically significant effect on the osteoarthrotic cartilage (Table). Theoretically, these results are not surprising, as the continuous distraction in a moving joint causes morphological changes in chondrocytes prior to degeneration and the forces exerted on cells distort their shape and stimulate alteration in cellular biochemistry and matrix metabolism (Hung et al 1997). Contrary to our results, van Valburg et al (2000) found no difference between the histology of the cartilage of distracted and non-distracted knees.…”

Articular cartilage defects in a rabbit model, retention rate of periosteal flap cover

“…On the other hand, joint immobilization has harmful effects on both periarticular tissue and cartilage (Hung et al 1997). …”

The diagnosis and treatment of sacroiliac joint abnormalities

“…With degeneration, the tribiology of the joint is affected, with areas of cartilage underloading 114 and bony overloading. 115,116 Metabolic, weight-bearing stresses and cartilage injury aggravate the changes caused by use and degeneration.…”