Objective To investigate whether combining use of platelet-rich plasma (PRP) and decalcified bone matrix (DBM) has synergistic action on promoting bone consol idation and heal ing. Methods Forty male New Zealand rabbits (weighing 2.2-2.8 kg) were randomly divided into 4 groups (n=10). The whole blood was extracted from the central aural artery and PRP was prepared with the Landesberg’s method. An 1 cm-defect was made below the tibiofibular joint of the lefttibia through osteotomy. In group A, defect was repaired by distraction osteogenesis (1 cm); in group B, defect was repaired with 0.5 cm DBM and then by distraction osteogenesis (0.5 cm); in group C, defect was repaired by distraction osteogenesis (1 cm) and local injection of 1 mL PRP; in group D, defect was repaired by 0.5 cm DBM combined with 1 mL PRP and then by distraction osteogenesis (0.5 cm). Then lengthening started at 7 days after operation, at a rate of 1 mm/day and 0.5 mm every time for 10 days (groups A and C) or for 5 days (groups B and D). After the lengthening, the consolidation was performed. The X-ray films were taken at 0, 12, 17, 27, and 37 days after operation. At 37 days after operation, the tibial specimens were harvested for Micro-CT scanning, three-dimensional reconstruction and biomechanical test. Results The X-ray films showed that new bone formation in groups B and C was obviously better than that in groups A and D at 37 days. The bone mineral density (BMD), bone mineral content (BMC), and bone volume fraction (BVF) of groups B and C were significantly higher than those of groups A and D (P lt; 0.05); the BMD and BMC of group C were significantly higher than those of group B (P lt; 0.05); the BVF had no significant difference between groups B and C (P gt; 0.05). There was no significant difference in BMD, BMC, and BVF between groups A and D (P gt; 0.05). The trabecula number (Tb.N) of group C was significantly more than that of other groups (P lt; 0.05), and the trabecula spacing (Tb.Sp) of group C was significantly smaller than that of other groups (P lt; 0.05), but no significant differencewas found among other groups (P gt; 0.05). There was no significant difference in the trabecula thickness among 4 groups (P gt; 0.05). The ultimate angular displacement had no significant difference among 4 groups (P gt; 0.05). The maximum torque of groups B and C was significantly higher than that of groups A and D (P lt; 0.05); the maximum torque of group C was significantly higher than that of group B (P lt; 0.05); no significant difference was found between groups A and D (P gt; 0.05). Conclusion In the rabbit bone defect/lengthening model, local injection of PRP can enhance bone consol idation effectively during consol idation phase. In normal distraction rate, DBM can promote bone consol idation during distraction osteogenesis. In the early stage of distraction osteogenesis, combining use of DBM and PRP can not further promote bone consolidation and healing.
ObjectiveTo investigate the effect, right timing, and mechanism of " accordion” technique on bone regeneration in rat distraction osteogenesis model.MethodsFifty-four 12-week-old male Sprague Dawley rats underwent right tibial distraction osteogenesis procedure. After a 5-day latency, the distraction was performed for 7 days followed by 6-week consolidation. All animals were randomly divided into 4 groups based on different periods of " accordion” maneuvers in consolidation phase: control group (n=18) with no manipulation, and three experimental groups including early-phase group (n=18), mid-phase group (n=12), and late-phase group (n=6) with " accordion” maneuvers applied at 1, 3, and 5 weeks, respectively. The duration of the " accordion” maneuver was 7 days consisting of a 3.5-day compression and 3.5-day distraction. Rats in control group and early-phase group were sacrificed at 2, 4, and 6 weeks of the consolidation phase; rats in mid-phase group were sacrificed at 4 and 6 weeks of the consolidation phase; and rats in late-phase group were sacrificed at 6 weeks of the consolidation phase. Bilateral tibias from 6 rats in each group at each time point were obtained. Callus formation was monitored by X-ray radiography every week; new bone was reconstructed by Micro-CT three-dimensional reconstruction. The change of bone structure was evaluated, and parameters containing bone volume (BV)/tissue volume (TV) ratio (BV/TV) and bone mineral density (BMD) in three thresholds (158-211, 211-1 000, 158-1 000) were recorded and calculated at 6 weeks. Mechanical test consisting of ultimate load, modulus of elasticity, and energy to failure was performed. Histological analysis, such as Von Kossa staining, Safranin O staining, and HE staining, was done. Immunohistochemical staining using markers of osterix (OSX), osteocalcin (OCN), and vascular endothelial growth factor (VEGF) was analyzed.ResultsImages of X-ray showed that callus formation increased significantly in the mid-phase group. Micro-CT three-dimensional reconstruction demonstrated the mid-phase group owned fastest reconstructed speed among 4 groups, the cortical bone was continual at 6 weeks. At 6 weeks, the BMD and BV/TV in thresholds 158-1 000 and 211-1 000 in mid-phase group were higher than those in other groups. The results of mechanical test showed that ultimate load, modulus of elasticity, and energy to failure in mid-phase group were significantly higher than those in other groups (P<0.05). Histological testing showed that the continuity of bone marrow cavity in mid-phase group was evident at 6 weeks after distraction. Immunohistochemical analyses confirmed the expression levels of osteogenesis (OCN, OSX) and angiogenesis (VEGF) elevated remarkably and then returned to normal in mid-phase group.ConclusionThe " accordion” technique is beneficial for new callus formation in distraction area. Applying the maneuver during the middle phase of the consolidation period was effective to accelerate new bone formation in rat distraction osteogenesis model.