Effect of low-level helium–neon laser therapy on histological and ultrastructural features of immobilized rabbit articular cartilage

The present study investigates whether low-level helium–neon laser therapy can increase histological parameters of immobilized articular cartilage in rabbits or not.Twenty five rabbits were divided into three groups: the experiment group, which received low-level helium–neon laser therapy with 13 J/cm2 three times a week after immobilization of their right knees; the control group which did not receive laser therapy after immobilization of their knees; and the normal group which received neither immobilization nor laser therapy. Histological and electron microscopic examinations were performed at 4 and 7 weeks after immobilization.Depth of the chondrocyte filopodia in four-week immobilized experiment group, and depth of articular cartilage in seven-week immobilized experiment group were significantly higher than those of relevant control groups (exact Fisher test, p = 0.001; student’s t-test, p = 0.031, respectively). The surfaces of articular cartilages of the experiment group were relatively smooth, while those of the control group were unsmooth.It is therefore concluded that low-level helium–neon laser therapy had significantly increased the depth of the chondrocyte filopodia in four-week immobilized femoral articular cartilage and the depth of articular cartilage in seven-week immobilized knee in comparison with control immobilized articular cartilage.