Objective To identify the expression of nerve growth factor (NGF) and its high affinity receptor (tyrosine kinase receptor A, TrkA) during bone induction by recombined human bone morphogenetic protein 2 (rhBMP-2) by immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR) and to discuss the role of NGF on the bone induction of the BMP. Methods Thirty-six ICR mice were divided into the experimental groupand the control group at random. rhBMP-2 /collagen sponge and collagen sponge were implanted into the right thigh muscle pouches of the mice in the experimental group and the control group, respectively. The tissues in the implanted site of the two groups were removed on the 7th, 14th and 21st day after the implantation. Histological, immunohistochemical and RT-PCR analyses were performed to detect osteoinductive effects of rhBMP-2 and the expression of NGF and TrkA. Results Gross observation showed that a solid lump was found in theright thigh in the experimental group on the 7th day and became harder on the 14th and 21st day, which was not found in the control group. rhBMP-2/collagen sponge displayed a potent ability to induce bone formation, while immunostaining for NGF and TrkA was observed in the course of osteoinduction by rhBMP-2. On the 7th day in the experimental group, NGF positive immunostaining reached the peak in thestage of chondrogenesis and there were a large number of cells expressing NGF, including fibroblasts, chondroblasts, chondrocytes, and osteoblasts; then, therewas a decrease in the number of the positivecells and in the intensity of immunostaining on the 14th and 21st day. Staining of TrkA wassimilar to that of NGF. The expression level of the mRNA of NGF during the course of bone induction peaked 7 days after the implantation and then decreased. Conclusion rhBMP-2/collagen is a kind of satisfactory osteoinductive material, and many different kinds of cells induced by rhBMP-2 can express NGF and TrkA, which suggests that NGF may play an important role in the osteogenesis initiated by exogenous BMP through direct and indirect pathways.
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.