BACKGROUND: Recent studies show that osteoprotegerin can inhibit the activity of osteoclast and regulate the process of cartilage reshaping. Osteoprotegerin plays a great role in maintaining the integrity of cartilage tissue of intervertebral disc.
OBJECTIVE: To determine the expression of osteoprotegerin in the intervertebral disk of the patients with lumbar disc degeneration (LDD), and then to analyze the relationship between the expression levels of osteoprotegerin and the severity of LDD.
METHODS: Sixty-four patients with LDD (LDD group) and twenty-five patients with disc burst fractures (control group) were enrolled in this study. The intervertebral disc tissues were collected after surgery. Then the mRNA expression and protein levels of osteoprotegerin in the intervertebral disk were examined by real-time polymerase chain reaction (PCR). The protein level of osteoprotegerin was determined by ELISA method. The grade of disc degeneration was classified according to MRI findings by Schneiderman’s classification and the association between the levels of osteoprotegerin and the Schneiderman’s grades was analyzed.
RESULTS AND CONCLUSION: The mRNA expression and protein levels of osteoprotegerin in the intervertebral disc in LDD group were significantly higher than that in the control group which were tested by real-time PCR method and ELISA method. Unconditional logistic regression analysis revealed that elevated mRNA expression and protein levels of osteoprotegerin were independent risk factors of the presence of LDD. In addition, the mRNA expression and protein levels of osteoprotegerin were both significantly correlated with Schneiderman’s grades (r =0.367, P < 0.001 and r =0.412, P < 0.001, respectively). Patients with higher Schneiderman’s grade showed relatively higher levels of osteoprotegerin. The levels of osteoprotegerin were significantly elevated in the intervertebral disc of patients with LDD and were significantly associated with the severity of LDD.