rhBMP-2 has been used to promote spinal fusion. Despite potential risk of complications, satisfied results could be obtained with low dose of rhBMP-2. Effect of early bone formation has been validated using rat ovariectomy osteoporosis model. However, whether it functioned in patients with osteoporosis remained unknown. In this study, the investigators intend to investigate whether rhBMP-2 promotes early bone formation in patients with osteoporosis after transforaminal lumbar interbody fusion (TLIF).

Pseudoarthrosis and many complications associated with iliac crest bone graft (ICBG) has prompted the spine surgeons to seek alternative methods to promote rate of spinal fusion. The rhBMP-2 received FDA approval in 2002 for use as an alternative to autograft for single-level anterior lumbar interbody fusion (ALIF). Many studies reported equivalent or better fusion rates. Recent studies, however, identified complications related to rhBMP-2 use such as osteolysis, graft subsidence, and retrograde ejaculation and other urological complications. Overdose of rhBMP-2 in patients may lead to complications mentioned above. A recent randomized controlled trial in 2022 confirmed a low dose usage of rhBMP-2 promoted fusion after TLIF (21.mg per fusion level) without increase in complications.

Current fusion methods achieve interbody fusion by filling the cage in the central region of the intervertebral space with bone graft material. However, the early fusion rates (at 3 and 6 months postoperatively) are often unsatisfactory. According to present literatures, the 3-month and 6-month fusion rates have ranged from 2.9% to 43.1% and 30% to 68.8%, respectively. Although a lack of fusion may be asymptomatic, it may potentially lead to complications, even a reoperation. In addition, failure to achieve early fusion may result in a delayed return to work, and reduced patient satisfaction, especially in patients with osteoporosis. Whether rhBMP-2 may lead to higher and early fusion rate in osteoporosis patient remains unknown.

In this study, the investigators intend to compare the time it takes to achieve osseous union/fusion and the clinical efficacy of using rhBMP-2 to control group in TLIF. The rhBMP-2 in the study is produced by a domestic enterprise (HANGZHOU JIUYUAN GENE ENGINEERING CO .,LTD., Hangzhou, China).

Inclusion Criteria:

• patients diagnosed with degenerative lumbar diseases.
• patients underwent one-level TLIF
• osteoporosis (DXA T≤-2.5)
• complete preoperative and follow-up data (imaging and health-related quality of life)

Exclusion Criteria:

• history of previous spinal surgery
• inflammatory and neoplastic diseases

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one year after the study is finished.

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