The objectives of this study are to investigate the changes in bone and articular cartilage in rat femur under 4-week tail suspension and to evaluate the therapeutic effects of laser acupuncture (LA). 18 rats were assigned into three groups. Group control (C) was under normal earth gravity, group tail-suspension (T) underwent tail suspension (TS) for 4 weeks, and group laser-acupuncture-therapy (L) were treated using LA at
(ST-36) acupoint on left hindlimb during TS. Bone mineral density (BMD) was quantified by peripheral computed tomography (pQCT) and the thickness of articular cartilage was measured by high-resolution ultrasound biomicroscopy (UBM) before and after TS. It was found that TS resulted in a significant decrease in BMD of femoral distal metaphysis (p < 0.01) and femoral shaft (p < 0.05) and significant cartilage thinning at medial femoral condyle and patella (p < 0.05). With LA therapy, an increase was found in BMD and cartilage thickness. The histological stains show an evidence of the changes including trabecular rarefaction, and cartilage thinning, proteoglycan loss and cell clustering in articular cartilage in group T as well as the corresponding therapeutic effects of LA in group L. This study demonstrates that the 4-week simulated microgravity has negative effects on bone and articular cartilage while LA has therapeutic improvement on the quality of the tissues.