Abstract: OBJECTIVE: Vertebroplasty is widely used in the treatment of osteoporotic vertebral fractures. At present, polymethyl methacrylate is still the most commonly used filling material for strengthening vertebral body, but it is not the most ideal filling material. Self-curing calcium phosphate cement is a new filling material developed in recent years, which can naturally heal with bone tissue and be absorbed and replaced by the human body. This meta-analysis systematically analyzed the clinical efficacy and safety of polymethyl methacrylate and self-solidifying calcium phosphate cement in vertebroplasty.  
METHODS: China National Knowledge Infrastructure, Wanfang database, Chinese Biomedical Medicine database, PubMed, EMbase, and Cochrane Library database were retrieved for clinical control studies regarding with polymethyl methacrylate and self-solidifying calcium phosphate cement treatment of osteoporotic vertebral compression fracture. The retrieval period was from the database inception to July 2020. The visual analogue scale score, vertebral kyphosis Cobb angle, vertebral body height, bone cement leakage rate, adjacent vertebral fracture rate, Oswestry dysfunction index, and clinical curative effect were used as the outcome indexes. All the literature screening, data extraction and research quality evaluation were carried out independently by two reviewers. In addition, the Cochrane Collaboration tool and the Newcastle-Ottawa scale were used to evaluate the quality of randomized controlled trials and cohort studies, respectively. RevMan 5.4 software was used for meta-analysis.
RESULTS: (1) A total of nine studies involving 593 patients were included in the meta-analysis; five of which were randomized controlled trials, and four were retrospective cohort studies. All of the selected studies were of high quality. (2) Meta-analysis results showed that there was no significant difference between the two filling materials in the following aspects, including visual analogue scale score (SMD=-0.45, 95%CI:-1.10-0.21, P=0.18), Cobb angle of vertebral kyphosis (MD=-0.16, 95%CI:-0.43-0.11, P=0.24), height of vertebral body (SMD=0.13, 95%CI:-0.12-0.37, P=0.32), leakage rate of bone cement (OR=1.30, 95%CI:0.67-2.54, P=0.44), Oswestry disability index (MD=3.31, 95%CI:-1.34-7.97, P=0.16), and clinical effective rate (OR=1.00, 95%CI:0.14-7.27, P=1.00). However, in terms of new fractures of adjacent vertebrae, the calcium phosphate cement group was significantly better than the polymethyl methacrylate group (OR=2.17, 95%CI:1.04-4.51, P=0.04).
CONCLUSION: The application of calcium phosphate cement in vertebroplasty has a significant advantage in reducing adjacent vertebral fractures compared with polymethyl methacrylate. The curative effect is similar in pain visual analogue scale score, vertebral kyphosis Cobb angle, vertebral body height, bone cement leakage rate, and Oswestry dysfunction index. However, more high-quality randomized controlled trials are needed to provide more sufficient evidence.

Key words: bone, osteoporosis, fracture, calcium phosphate, polymethyl methacrylate, bone cement, vertebroplasty, vertebral body, meta-analysis