RESUMO
Objective:To investigate the physicochemical and biological properties of different magnesium modified calcium phosphate bone cements.Methods:The different magnesium modified calcium phosphate bone cements were divided into magnesium citrate, magnesium lactate, magnesium malate, magnesium phosphate and magnesium glycinate groups, each of which was added with different magnesium agents in the proportion of 0%, 1%, 3% and 5% of the total weight of calcium phosphate bone cements. The initial and final setting time, injectability, anti-collapse performance and compressive strength of different magnesium modified calcium phosphate bone cements were tested. Furthermore, the screened bone cement extracts were used to culture with third generation osteoblasts. Bioactivity assays were performed using the Cell Proliferation and Toxicity Assay Kit (CCK-8). Alkaline phosphatase (ALP) staining and Alizarin Red S (ARS) staining were performed on osteoblasts to observe the osteogenic activity of magnesium malate modified calcium phosphate bone cements.Results:The addition of different proportions of different magnesium agents led to the shortening of the initial and final setting time of modified calcium phosphate bone cements. Moreover, the final setting time of 5% magnesium malate modified calcium phosphate bone cements was the shortest (<40 minutes), which was significantly shorter compared with other magnesium agents in the same proportion (all P<0.05). With the addition of different magnesium agents in different proportions, the injectability of bone cements was gradually increased, and the injectability of 5% magnesium malate calcium phosphate bone cements reached the highest for (87.3±1.9)%, which was significantly increased compared with other magnesium agents in the same proportion (all P<0.05). The anti-collapse performance of bone cements was decreased with the addition of different magnesium agents in different proportions. Magnesium citrate, magnesium phosphate and magnesium glycinate modified calcium phosphate bone cements could not resist the flushing of deionized water. In particular, magnesium malate modified calcium phosphate bone cements had the best anti-collapse performance, with the maximum weight loss rate for only (9.8±2.3)% after 30 minutes of deionized water flushing, which was better than the rest of the groups (all P<0.05). The compressive strength of magnesium lactate and magnesium phosphate modified calcium phosphate bone cements showed a decrease compared with original calcium phosphate bone cements, while the compressive strength of magnesium citrate and magnesium malate modified calcium phosphate bone cements was significantly increased compared with original calcium phosphate bone cements, of which 3% magnesium malate modified calcium phosphate bone cements had the greatest compressive strength of (6.2±0.2)MPa, significantly higher than the rest of the groups (all P<0.05). The sieve test yielded magnesium malate modified calcium phosphate bone cement, which had a weight loss of (27.0±0.9)% at 35 days in vitro. The release of magnesium ions was increased with increasing magnesium malate dose in the in vitro environment of magnesium malate modified calcium phosphate bone cements in different ratios. A stable magnesium ion release was achieved within 35 days.Also, the pro-proliferative and osteogenic effects of modified calcium phosphate bone cements on osteoblasts were more obvious with increase of magnesium malate dose. For 5% magnesium malate modified calcium phosphate bone cements, the cell number, ALP staining area ratio and calcium nodule area ratio were significantly increased compared with the groups in the proportion of 0% and 1% magnesium malate (all P<0.05). Conclusions:Among magnesium citrate, magnesium lactate, magnesium malate, magnesium phosphate and magnesium glycinate modified calcium phosphate bone cements, magnesium malate modified calcium phosphate bone cements have relatively suitable setting time, excellent anti-collapse performance and mechanical strength. Meanwhile, 5% magnesium malate modified calcium phosphate bone cements have better biological activity among different ratios of magnesium malate modified calcium phosphate bone cements, suggesting a potential value for clinical application.
RESUMO
Objective:To compare the clinical effect of combined anterior and posterior approach and posterior median approach to treat O'Driscoll type III b fracture of ulnar coronoid process.Methods:A retrospective case control study was made on 67 patients with O'Driscoll type III b fracture of ulnar coronoid process treated in Honghui Hospital, Xi'an Jiaotong University from January 2015 to January 2019, including 35 males and 32 females, aged from 21 to 61 years [(38.0±9.4)years]. Among them, 31 patients were treated with combined anterior and posterior approach for reduction and internal fixation (combined approach group), and 36 patients with median posterior elbow approach group for reduction and internal fixation (posterior elbow approach group). The operation time, amount of intraoperative blood loss and fracture healing time were compared between groups. The visual analogue score (VAS), elbow joint range of motion and Mayo elbow performance score (MEPS) were assessed for pain and function evaluation at postoperative 1, 3, 6 months and at the last follow-up. The occurrence of complications were observed as well.Results:All patients were followed up for 12 to 28 months [(20.1±4.2)months]. There was no significant difference in operation time and VAS between the two groups ( P>0.05). The intraoperative blood loss [(133.6±20.3)ml] and fracture healing time [(12.3±1.7)months] in combined approach group were less or shorter than those in posterior elbow approach group [(144.4±22.1)ml, (13.2±2.0)months] ( P<0.05). The range of flexion and extension of elbow joint in combined approach group [(88.7±10.8)°, (111.1±13.9)°, (121.3±14.1)°, (127.1±13.3)°] was higher than that in posterior elbow approach group [(74.5±11.8)°, (97.6±12.6)°, (111.3±13.0)°, (115.2±12.7)°] at postoperative 1, 3, 6 months and at the last follow-up ( P<0.05). The MEPS in combined approach group [(31.7±8.6)points, (55.6±9.3)points, (84.6±10.5)points, (85.0±10.3)points] was higher than that in posterior elbow approach group [(27.2±8.2)points, (50.7±8.7)points, (77.4±11.2)points, (80.1±9.4)points] at postoperative 1, 3, 6 months and last follow-up ( P<0.05). The incidence of complications in combined approach group [10%(3/31)] was lower than that in posterior elbow approach group [31%(11/36)]( P<0.05). Conclusion:Compared with the simple posterior elbow median approach, the combined anterior and posterior elbow approach for treatment of O'Driscoll type IIIb fracture of ulnar coronoid process has lower intraoperative blood loss, faster fracture healing, lower incidence of complications and better elbow function.