Lateral-Opening Injection Tool Used in Percutaneous Vertebroplasty to Treat Asymptomatic Osteoporotic Vertebral Burst Fractures: A Retrospective Study.

OBJECTIVE: The adequate management of asymptomatic osteoporotic vertebral burst fractures (OVBFs) was still controversial. Percutaneous vertebroplasty (PVP) could achieve quick recovery with minor trauma, but there were certain safety problems by traditional bone cement injection method. Thus, the aim of this study was to assess the efficacy of lateral-opening injection tool used in PVP treating patients with asymptomatic OVBFs. METHODS: This was a retrospective study of OVBFs treated in our institute from March 2016 to March 2020. A total of 66 patients (mean age 72.10 ± 7.98 years, with 21 men and 45 women) who were diagnosed with acute asymptomatic OVBFs with mild spinal canal compromise were treated with PVP by using a lateral-opening injection tool. Two puncture needles were simultaneously placed transpedicularly in the fractured vertebra, and the inner core was removed, and the lateral-opening injection tool was inserted. The adjustment of lateral hole was to improve the distribution height of bone cement and avoid the entry of bone cement into the posterior wall of vertebral body. Related clinical outcomes and images were assessed, including back pain (visual analog scale [VAS]), vertebral height ratio (fractured vertebral height/average adjacent nonfractured vertebral height), kyphosis Cobb angle, union of the fractured vertebral posterior wall, distribution of bone cement, surgical data, and complications. RESULTS: The average follow-up time of all cases was 21.23 ± 9.35 months. The mean amount of bone cement was 3.28 ± 0.35 ml in the vertebrae and the mean operative time was 34.02 ± 5.23 min. There were 60 cases of bone cement that contacted the upper and lower endplates on at least one side. There was no cement leakage into the spinal canal or fracture displacement of the posterior wall of the vertebral body in all cases. The VAS scores were 3.78 ± 0.42 at 1 day postoperatively and 0.53 ± 0.40 at the last follow-up, significantly lower than 8.40 ± 0.48 preoperatively (p < 0.05). The average height ratio of anterior, middle, and posterior vertebral body after operation increased compared with that pre-operation (p < 0.05), and the postoperative kyphosis angle decreased (p < 0.05). At 6 months follow-up, there was no significant height loss of the vertebral body. Computed tomography examination 3 months postoperatively showed that the fracture of posterior vertebral wall healed well in all cases. There were seven cases of bone cement leakage without clinical symptoms and two adjacent vertebral fractures caused by falling. There were no cases of deep vein embolism, lower limb muscle atrophy, pneumonia, decubitus. CONCLUSION: The lateral opening tool can be safely and effectively used in the PVP treatment on asymptomatic OVBFs with mild spinal canal compromise.

Bone Mesenchymal Stem Cell-Enriched ß-Tricalcium Phosphate Scaffold Processed by the Screen-Enrich-Combine Circulating System Promotes Regeneration of Diaphyseal Bone Non-Union.

Bone non-union after fracture, considered a therapeutic challenge for orthopedics, always needs a reversion surgery, including autograft transplantation (AGT). However, adverse events related to autograft harvest cannot be ignored. Our group designed a novel system called the bone marrow stem cell Screen-Enrich-Combine Circulating System (SECCS) by seeding mesenchymal stem cells (MSCs) into ß-tricalcium phosphate (ß-TCP) during surgery to thereafter rapidly process bioactive bone implantation. In this retrospective case-control study, 30 non-union patients who accepted SECCS therapy and 20 non-union patients who accepted AGT were enrolled. By SECCS therapy, the MSC-enriched ß-TCP particles were implanted into the non-union gap. During the enrichment procedure, a significant proportion of MSCs were screened and enriched from bone marrow into porous ß-TCP particles, and the cells possessed the capacity for three-line differentiation and were CD90+/CD105+/CD34-/CD45-. Approximately 82.0±10.7% of MSCs were enriched from 60 mL bone marrow without damaging cell viability, and approximately 11,444.0±6,018 MSCs were transplanted per patient. No implant-related infections occurred in any case. After 9 months of follow-up, 27 patients (90%) in the SECCS group acquired clinical union, compared with 18 patients (90%) in the AGT group (clinical union time, P = 0.064), and postoperative radiographic union score at 9 months post-operation was similar between the two groups. In conclusion, the SECCS could concentrate a large proportion of MSCs from bone marrow to acquire enough effective cells for therapy without in vitro cell culture. Bone substitutes processed by SECCS demonstrated encouraging promotion of bone regeneration and showed a satisfactory clinical curative effect for diaphyseal bone non-union, which was non-inferior to AGT.

Biocompatibility of magnesium-zinc alloy in biodegradable orthopedic implants.

In this study, magnesium-zinc (Mg-Zn) alloy was investigated as a biodegradable orthopedic implant. MC3T3-E1 cell attachment, mineralization and osteogenic-specific mRNA expression were assessed for as measurements of the in vitro biocompatibility of Mg-Zn alloy. In vivo degradation of the Mg-Zn alloy and the accompanying new bone formation in the femoral marrow cavity were analyzed by scanning electron microscopy and histomorphological analysis. Results showed that MC3T3-E1 cells cultured on Mg-Zn alloy samples manifested better attachment and mineralization ability, as well as improved mRNA expression of collagen 1 α 1 (COL1α1) and osteocalcin (OC), compared with cells seeded on poly-L-lactic acid (PLLA) samples. In vivo experiments demonstrated that, compared with PLLA materials, the Mg-Zn alloy not only degraded faster, but was accompanied by considerable new bone formation around the samples. Our data indicate that Mg-Zn alloy has excellent biocompatibility for application as degradable bone implants.

Research on an Mg-Zn alloy as a degradable biomaterial.

In this study a binary Mg-Zn magnesium alloy was researched as a degradable biomedical material. An Mg-Zn alloy fabricated with high-purity raw materials and using a clean melting process had very low levels of impurities. After solid solution treatment and hot working the grain size of the Mg-Zn alloy was finer and a uniform single phase was gained. The mechanical properties of this Mg-Zn alloy were suitable for implant applications, i.e. the tensile strength and elongation achieved were approximately 279.5MPa and 18.8%, respectively. The results of in vitro degradation experiments including electrochemical measurements and immersion tests revealed that the zinc could elevate the corrosion potential of Mg in simulated body fluid (SBF) and reduce the degradation rate. The corrosion products on the surface of Mg-Zn were hydroxyapatite (HA) and other Mg/Ca phosphates in SBF. In addition, the influence caused by in vitro degradation on mechanical properties was studied, and the results showed that the bending strength of Mg-Zn alloy dropped sharply in the earlier stage of degradation, while smoothly during the later period. The in vitro cytotoxicity of Mg-Zn was examined. The result 0-1 grade revealed that the Mg-Zn alloy was harmless to L-929 cells. For in vivo experiments, Mg-Zn rods were implanted into the femoral shaft of rabbits. The radiographs illustrated that the magnesium alloy could be gradually absorbed in vivo at about 2.32mm/yr degradation rate obtained by weight loss method. Hematoxylin and eosin (HE) stained section around Mg-Zn rods suggested that there were newly formed bone surrounding the implant. HE stained tissue (containing heart, liver, kidney and spleen tissues) and the biochemical measurements, including serum magnesium, serum creatinine (CREA), blood urea nitrogen (BUN), glutamic-pyruvic transaminase (GPT) and creatine kinase (CK) proved that the in vivo degradation of Mg-Zn did not harm the important organs. Moreover, no adverse effects of hydrogen generated by degradation had been observed and also no negative effects caused by the release of zinc were detected. These results suggested that the novel Mg-Zn binary alloy had good biocompatibility in vivo.

[Experimental study on the treatment of femur head necrosis with tricalcium phosphate and platelet-rich plasma].

OBJECTIVE: To study the mechanism of compound of calcium phosphate (TCP) and platelet-rich plasma(PRP) in the treatment of femoral head necrosis. METHODS: The left femoral heads of 48 New Zealand white rabbits were frozen by liquid nitrogen as to make the model of femoral head necrosis. Twenty-four rabbits were randomly chosen as the experimental group and their femoral heads were filled with TCP/PRP. The other 24 rabbits were used as the control group and their femoral heads were filled only with TCP. They were sacrificed at 2, 4, 8, 12 weeks after operation. The specimens were examined with X-ray and histological study. RESULTS: At 2 weeks after operation, there was no significant difference in femoral head density between the two groups. Four weeks after operation, femoral head density decreased in both groups, while it decreased more in the control group. At 8, 12 weeks after operation, the density of the femoral heads in both groups increased, and it was higher in the experimental group. Histology examination showed that there was no difference between the two groups 2 weeks after operation. The head became flat at 4 weeks. Control group had more defects. At 4, 8, 12 weeks, more repairs were observed in the experimental group than that in the control group. The amount and maturity of osteogenesis in experimental group were much more greater than those in control group. Bone histomorphometry showed that the volume of the trabecular was larger in the experimental group (36.65% +/- 7.22%, 38.29% +/- 4.28%, 39.24% +/- 3.42%) than that of control group (P < 0. 05). CONCLUSION: TCP/PRP does not only provide osteoblasts scaffold, but also promotes bone formation and the head repair. TCP/PRP is a good biomaterial for the treatment of femur head necrosis.