Osteoporotic vertebral compression fracture (OVCF) is a common cause of pain and disability and is steadily increasing due to the growth of the elderly population. To date, percutaneous vertebroplasty (PVP) and percutaneous kyphoplasty (PKP) are almost universally accepted as appropriate vertebral augmentation procedures for OVCFs. There are many advantages of vertebral augmentation, such as short surgical time, performance under local anaesthesia, and rapid pain relief. However, there are certain issues regarding the utilization of these vertebral augmentations, such as loss of vertebral height, cement leakage, and adjacent vertebral refracture. Hence, the treatment for OVCF has changed in recent years. Satisfactory clinical results have been obtained worldwide after application of the OsseoFix System, the SpineJack System, radiofrequency kyphoplasty of the vertebral body, and the Kiva VCF treatment system. The following review discusses the development of the current techniques used for vertebral augmentation.

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Background Percutaneous vertebroplasty was the most common strategy for osteoporotic vertebral compression fracture. However, refracture after vertebroplasty also occurred and bone mineral density (BMD) was one of the main factors associated with refracture after percutaneous vertebroplasty. Aims To investigate the efficacy of a short-sequential treatment of teriparatide followed by alendronate on prevention of refracture after percutaneous vertebroplasty in osteoporotic patients, and compare it with the therapy of alendronate alone. Methods From January 2018 to January 2020, we recruited 165 female osteoporosis patients after percutaneous vertebroplasty who were assigned into sequential treatment of teriparatide followed by alendronate group (TPTD + ALN group) and alendronate alone group (ALN group). The vertebral fracture occurred during this process was also recorded in both the groups. A total of 105 participants completed the 1-year follow-up. Furthermore, BMD and serum procollagen type I N-terminal propeptide (PINP) and C-terminal cross-linking telopeptide of type I collagen (CTX) were compared between the two groups during 1-year follow-up. Results The 105 patients were finally included, with 59 in ALN group and 46 in TPTD + ALN group. During 1-year follow-up, the vertebral refracture rate in TPTD + ALN group was much lower than that in ALN group (2.2% vs. 13.6%, p < 0.05). At 12 months, the BMDs at lumbar in TPTD + ALN group were significantly elevated when compared to the ALN group (0.65 ± 0.10 vs. 0.57 ± 0.07, p < 0.001). Discussion and conclusion A short-sequential administration of teriparatide followed by alendronate was more effective in elevating the BMD and decreasing the refracture rate at 12-month follow-up, compared to the counterpart with alendronate alone.

Bone and cartilage regeneration is a dynamic and complex process involving multiple cell types such as osteoblasts, osteoclasts, endothelial cells, etc. Stem cells have been proved with efficient capability to promote bone and cartilage regeneration and repair but the usage of cells harbors some important safety issues, such as immune rejection and carcinogenicity. Exosomes are non-cell structures secreted from various cells. The content of exosomes is enriched with proteins, such as cytoskeleton proteins, adhesion factors, transcription factors, etc. and a variety of nucleic acids, such as mRNA (Messenger RNA), long-chain non-coding RNA, microRNA (miRNA), etc. Exosomes can deliver a variety of contents from the parent cells to the recipient cells in different tissue backgrounds, influencing the phenotype and function of the recipient cells. Recent studies have demonstrated that miRNAs play significant roles in bone formation, suggesting that miRNAs may be novel therapeutic targets for bone and cartilage diseases. Exosomes have been shown with low/no immune rejection in vivo, no carcinogenic risk of infection, nor other side effects. In recent years, stem cell exosomes have been utilized to promote bone and cartilage regeneration processes during bone defect, bone fracture, cartilage repair, osteoporosis and osteoarthritis. In this review, we discuss different exosomes derived from stem cells and their interactions with target cells, including osteoblasts, chondrocytes and osteoclasts. We also put special highlights on the various signaling pathways involved in stem cell exosome-related bone and cartilage regeneration.