【Abstract】 Objective To find out the best method to prepare platelet-rich plasma (PRP) and to evaluate the effect of PRP gel on skin flap survival and its mechanism. Methods Totally, 72 Wistar rats (aged 12 weeks, weighing 250-300 g) were used for the experiment. The arterial blood (8-10 mL) were collected from the hearts of 24 rats to prepare PRP with three kinds of centrifuge methods: in group A, 200 × g centrifuge for 15 minutes, and 500 × g centrifuge for 10 minutes；in group B, 312 × g centrifuge for 10 minutes, and 1 248 × g centrifuge for 10 minutes；and in group C, 200 × g centrifuge for 15 minutes, and 200 × g centrifuge for 10 minutes. The platelet was counted in the whole blood, PRP, and platelet-poor plasma (PPP) to determine an ideal centrifuge. PRP, PPP, and the serum after first centrifuge were collected. The concentrations of platelet-derived growth factor BB (PDGF-BB) and transforming growth factor β1 (TGF-β1) were measured in the PRP, PPP, and serum using the enzyme-linked immunosorbent assay method, and PRP and PPP gels were prepared. The flaps of 11 cm × 3 cm in size were elevated on the back of 48 rats, which were divided into 3 groups: PRP gel (PRP group, n=16) and PPP gel (PPP group, n=16) were injected, no treatment was given in the control group (n=16). The flap survival rate was measured at 7 days. Histological and real-time PCR were used to count the inflammatory cells and blood vessel density, and to detect the expressions of vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), PDGF-AA, and PDGF-BB mRNA at 8 hours, 24 hours, 3 days, and 7 days. Results Platelet counting showed platelet in group A was the highest. ELISA evaluation showed that the concentrations of TGF-β1 and PDGF-BB were significantly higher in PRP than in PPP and serum (P lt; 0.05). The flap survival rate was 61.2% ± 9.1% in PRP group, showing significant differences (P lt; 0.05) when compared with that in PPP group (35.8% ± 11.3%) and control group (28.0% ± 5.4%). The inflammatory cells were significantly lower and the blood vessel density was significantly higher in PRP group than in PPP group and control group (P lt; 0.05). When compared with PPP group and control group, the expressions of VEGF and PDGF-BB increased at all time after operation in PRP group; the expression of EGF increased within 24 hours; and the expression of PDGF-AA increased after 3 days. There were significant differences in PDGF-AA mRNA at 3 days and 7 days, PDGF-BB mRNA at 8 hours, VEGF mRNA at 24 hours and 3 days, and EGF mRNA at 24 hours between PRP group and PPP and control groups (P lt; 0.05). Conclusion 200 × g centrifuge for 15 minutes and 500 × g centrifuge for 10 minutes is the best PRP preparation method. PRP can improve the skin flap survival by regulating the genes involved in angiogenesis.
ObjectiveTo evaluate the effectiveness of internal fixation with headless compression hollow embedding screws in the treatment of intraarticular fracture of elbow.MethodsBetween March 2012 and September 2018, 12 patients with intraarticular fracture of elbow were treated with internal fixation with headless compression hollow embedding screws. There were 7 males and 5 females with an average age of 50.3 years (range, 22-65 years). Cause of injury included falling in 7 cases, falling from high places in 4 cases, and traffic accident in 1 case. Ten patients were distal humerus fractures which were classified as type 13-B3 in 8 cases and type 13-C3 in 2 cases according to the International Association of Internal Fixation Research (AO/ASIF). Two patients were radial head fractures which were classified as type Ⅲ according to the modified Mason classifications. The preoperative visual analogue scale (VAS) score was 8.25±0.83. The time from injury to operation was 3-5 days (mean, 3.7 days).ResultsAll incisions healed by first intention. All 12 patients were followed up 6-15 months, with an average of 8.4 months. The results of X-ray films and CT examination showed that the fracture ends were anatomic reduction, and the fractures healed at 6-11 months after operation, with an average of 7.8 months. One patient had heterotopic ossification at 4 months after operation. The VAS scores were 5.17±0.79 at 2 weeks after operation and 0.50±0.50 at last follow-up. There were significant differences between the time points (P<0.05). At last follow-up, the Mayo elbow function score was 68-95, with an average of 83.9. The activity of elbow joint recovered.ConclusionThe intraarticular fracture of elbow can be firmly fixed by the headless compression hollow embedding screw, which can allow the early functional training of the elbow joint, reduce the incidence of heterotopic ossification, and obtain good effectiveness.