[Effect of calcium sulfate on promoting natural healing of docking sites during bone transport].

OBJECTIVE: To observe clinical effect of calcium sulfate on promoting natural healing of docking sites during bone transport. METHODS: A retrospective study was performed on the patients with posttraumatic chronic osteomyelitis treated by bone transport and calcium sulfate implantation from January 2013 to January 2018. There were 23 males and 4 females, aged from 20 to 61 years old with an average of (44.30±10.00) years, the courses of disease ranged from 3 to 86 months with an average of(13.26±16.47) months. Sixteen patients with posttraumatic chronic osteomyelitis were caused by internal fixation of closed fractures, and 11 patients were caused by open fractures. The length of bone defects after debridement ranged from 4 to 14 cm with an average of(9.11±2.57) cm. Postoperative complications, natural healing rate of the docking sites, external fixation index were observed, Checketts & Otterburn pin-tract infection classification was used to evaluate pin-tract infection, and Paley evaluation criteria was used to evaluate bone and function results. RESULTS: Twenty-seven patients were followed up from 26 to 41 months with an average of (31.32±3.37) months. It did not happened skin embedded between bone stumps in all patients. All patients obtained bone union at (17.78±5.43) months after operation.Among them, 25 patients healed naturally in the docking sites, 2 patients with poor compliance healed after debridement and bone grafting in the docking sites. One patient occurred equines deformity, and no re-fracture or recurrence of infection occurred. According to Checketts & Otterburn pin tract infection classification, 22 patients (41 pin tracts)occurred pin-tract infection with varying degrees. The average external fixation index was (2.02±0.24) months/cm(ranged from 1.6 to 2.4 months/cm). According to Paley evaluation criteria, bony results showed 21 patients obtained excellent results, 5 good, and 1 moderate;functional results showed 19 patients got excellent results, 7 good, and 1 moderate. CONCLUSION: During bone transport, the implantation of calcium sulfate on the bone defect areas could prevent skin embedding between the bone stumps, benefit for the natural healing of the docking sites, and could avoid the second-stage debridement and bone grafting for most patients. However, it should be noted that compliance needs to be increased.

Promotion of peripheral nerve regeneration of a peptide compound hydrogel scaffold.

BACKGROUND: Peripheral nerve injury is a common trauma, but presents a significant challenge to the clinic. Silk-based materials have recently become an important biomaterial for tissue engineering applications due to silk's biocompatibility and impressive mechanical and degradative properties. In the present study, a silk fibroin peptide (SF16) was designed and used as a component of the hydrogel scaffold for the repair of peripheral nerve injury. METHODS: The SF16 peptide's structure was characterized using spectrophotometry and atomic force microscopy, and the SF16 hydrogel was analyzed using scanning electron microscopy. The effects of the SF16 hydrogel on the viability and growth of live cells was first assessed in vitro, on PC12 cells. The in vivo test model involved the repair of a nerve gap with tubular nerve guides, through which it was possible to identify if the SF16 hydrogel would have the potential to enhance nerve regeneration. In this model physiological saline was set as the negative control, and collagen as the positive control. Walking track analysis and electrophysiological methods were used to evaluate the functional recovery of the nerve at 4 and 8 weeks after surgery. RESULTS: Analysis of the SF16 peptide's characteristics indicated that it consisted of a well-defined secondary structure and exhibited self-assembly. Results of scanning electron microscopy showed that the peptide based hydrogel may represent a porous scaffold that is viable for repair of peripheral nerve injury. Analysis of cell culture also supported that the hydrogel was an effective matrix to maintain the viability, morphology and proliferation of PC12 cells. Electrophysiology demonstrated that the use of the hydrogel scaffold (SF16 or collagen) resulted in a significant improvement in amplitude recovery in the in vivo model compared to physiological saline. Moreover, nerve cells in the SF16 hydrogel group displayed greater axon density, larger average axon diameter and thicker myelin compared to those of the group that received physiological saline. CONCLUSION: The SF16 hydrogel scaffold may promote excellent axonal regeneration and functional recovery after peripheral nerve injury, and the SF16 peptide may be a candidate for nerve tissue engineering applications.