Serum bone turnover biomarkers in early postoperative period related to the spontaneous resolution of disc herniation

A new way of induction surgery to obtain induced resorption of herniated nucleus pulposus (iRHNP) was recently proposed by our team, both cervical or lumbar disc herniation (CDH or LDH), when bony repair of the decompression groove simultaneously started, suggesting the possible relation to iRHNP mechanism. Since some biomarkers from peripheral blood are regarded as indicators of bone turnover, the role of circulating biomarkers for iRHNP that may reveal the mechanism remains to be determined. This study aimed to identify whether potential biomarkers changed in coincidence with the degree of iRHNP in CDH and LDH after induction surgery. A total of 73 CDH patients and 135 LDH patients, diagnosed with cervical myelopathy or lumbar stenosis accepted induction surgery, were enrolled in this retrospective study. The medical information such as T-score and volumes of CDH and LDH was monitored. The serum concentrations of five biomarkers such as osteocalcin (OCN), 25-dihydroxyvitamin D3 (25-OH-D3), β-Cross Laps, amino-terminal propeptide of type I collagen (PINP) and parathyroid hormone (PTH), and the concentration of BMP-2 were measured. As a result, the reduction in CDH and LDH volume (iRHNP) was firstly confirmed 1 week after induction surgery. The iRHNP was seen in 72.16% of CDHs and 67.81% of LDHs, with no statistical difference. In addition, the volume changes ratio in median was - 27.8% in CDHs, a greater degree than - 21.0% in LDHs. Accompanied with iRHNP occurrence, biomarkers of OCN, 25-OH-D3, PINP and PTH were significantly down-regulated while β-Cross Laps was significantly up-regulated in circulation. Correlation ships between the osteoporosis and iRHNP degree were identified. Meanwhile, the biomarkers of pre-operative circuiting levels of OCN and PINP were reflective to the degree of iRHNP. In conclusion, we found that T-score/osteoporosis was linked to iRHNP whilst serum biomarkers were predictive of the change degrees of disc herniation volume in both cervical and lumbar spine. This study suggested the iRHNP mechanism related to the circulating biomarkers in early postoperative period reflective for bone metabolism.