ObjectiveTo observe the effect of stromal vascular fraction cells (SVFs) from rat fat tissue combined with sustained release of recombinant human bone morphogenetic protein-2 (rhBMP-2) in promoting the lumbar fusion in rat model.MethodsSVFs were harvested from subcutaneous fat of bilateral inguinal region of 4-month-old rat through the collagenase I digestion. The sustained release carrier was prepared via covalent bond of the rhBMP-2 and β-tricalcium phosphate (β-TCP) by the biominetic apatite coating process. The sustained release effect was measured by BCA method. Thirty-two rats were selected to establish the posterolateral lumbar fusion model and were divided into 4 groups, 8 rats each group. The decalcified bone matrix (DBX) scaffold+PBS, DBX scaffold+rhBMP-2/β-TCP sustained release carrier, DBX scaffold+SVFs, and DBX scaffold+rhBMP-2/β-TCP sustained release carrier+SVFs were implanted in groups A, B, C, and D respectively. X-ray films, manual spine palpation, and high-resolution micro-CT were used to evaluate spinal fusion at 8 weeks after operation; bone mineral density (BMD) and bone volume fraction were analyzed; the new bone formation was evaluated by HE staining and Masson’s trichrome staining, osteocalcin (OCN) was detected by immunohistochemical staining.ResultsThe cumulative release amount of rhBMP-2 was about 40% at 2 weeks, indicating sustained release effect of rhBMP-2; while the control group was almost released within 2 weeks. At 8 weeks, the combination of manual spine palpation, X-ray, and micro-CT evaluation showed that group D had the strongest bone formation (100%, 8/8), followed by group B (75%, 6/8), group C (37.5%, 3/8), and group A (12.5%, 1/8). Micro-CT analysis showed BMD and bone volume fraction were significantly higher in group D than groups A, B, and C (P<0.05), and in group B than groups A and C (P<0.05). HE staining, Masson’s trichrome staining, and immunohistochemistry staining for OCN staining exhibited a large number of cartilage cells with bone matrix deposition, and an active osteogenic process similar to the mineralization of long bones in group D. The bone formation of group B was weaker than that of group D, and there was no effective new bone formation in groups A and C.ConclusionThe combination of sustained release of rhBMP-2 and freshly SVFs can significantly promote spinal fusion in rat model, providing a theoretical basis for further clinical applications.
ObjectiveTo compare the effectiveness of posterior malleolus fractures treated by plate and screw internal fixation through posterolateral approach.MethodsThe clinical data of 95 patients with posterior malleolus fractures who were admitted between January 2016 and December 2019 and met the selection criteria were retrospectively analysed. They were divided into plate group (44 cases, treated with posterolateral plate internal fixation) and screw group (51 cases, treated with posterolateral screw internal fixation) according to different treatment methods. There was no significant difference in general data between the two groups of patients such as age, gender, cause of injury, side of injury, ankle fracture or injury classification, time from injury to operation, and percentage of posterior ankle fracture area to the distal tibia articular surface (P>0.05). The operation time, hospital stay, fracture healing time, and surgical complications were compared between the two groups. Imaging examinations (X-ray film, CT scan and reconstruction) were used to assess the reduction quality of ankle fracture, articular congruity, and re-displacement in ankle fracture. At last follow-up, the pain visual analogue scale (VAS) score was used to evaluate the patients’ pain, and the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score was used to evaluate ankle joint function.ResultsPatients in both groups were followed up 6-30 months, with an average of 18.2 months. The operation time of the plate group was significantly longer than that of the screw group (U=−2.040, P=0.041); there was no significant difference in hospital stay between the two groups (U=−1.068, P=0.285). Incision swelling occurred in 2 cases in the plate group, sural nerve injury in 3 cases, and traumatic arthritis in 2 cases during follow-up. In the screw group, there were 1, 2, and 2 cases, respectively. The incidence of complications in the two groups (15.9% vs. 9.8%) was not significantly different (P=0.372). All patients who underwent tibiofibular screw fixation underwent the removal of the tibiofibular screw before taking full weight bearing at 12 weeks after operation, and there was no screw fracture and retention. During the follow-up, there was no infection, re-displacement of fracture, delayed bone union or nonunion, and there was no significant difference in fracture healing time between the two groups (t=0.345, P=0.731). There was no significant difference between the two groups of reduction quality of ankle fracture and articular congruity evaluation results (P>0.05). At last follow-up, there was no significant difference in VAS score, AOFAS ankle-hindfoot score and evaluation grade between the two groups (P>0.05).ConclusionBoth the plate and screw internal fixation through posterolateral approach can achieve satisfied effectiveness in the treatment of posterior ankle fractures with maintenance of fracture reduction, and recovery of ankle joint function. The screw internal fixation has the advantages of minimal invasion and shorter operation time.