Intramedullary Defect Research Articles

Effect of triple growth factor controlled delivery by a brushite–PLGA system on a bone defect

Bone regeneration is a complex process that involves multiple cell types, growth factors (GFs) and cytokines. A synergistic contribution of various GFs and a crosstalk between their signalling pathways was suggested as determinative for the overall osteogenic outcome.The purpose of this work was to develop a brushite–PLGA system, which controls the release rate of the integrated growth factors (GFs) to enhance bone formation.The brushite cement implants were prepared by mixing a phosphate solid phase with an acid liquid phase. PDGF (250ng) and TGF-β1 (100ng) were incorporated into the liquid phase. PLGA microsphere-encapsulated VEGF (350ng) was pre-blended with the solid phase. VEGF, PDGF and TGF-β1 release kinetics and tissue distributions were determined using iodinated (125I) GFs.In vivo results showed that PDGF and TGF-β1 were delivered more rapidly from these systems implanted in an intramedullary defect in rabbit femurs than VEGF. The three GFs released from the brushite–PLGA system remained located around the implantation site (5cm) with negligible systemic exposure. Bone peak concentrations of approximately 4ng/g and 1.5ng/g of PDGF and TGF-β1, respectively were achieved on day 3. Thereafter, PDGF and TGF-β1 concentrations stayed above 1ng/g during the first week. The scaffolds also provided a VEGF peak concentration of nearly 6ng/g on day 7 and a local concentration of approximately 1.5ng/g during at least 4 weeks. Four weeks post implantation bone formation was considerably enhanced with the brushite–PLGA system loaded with each of the three GFs separately as well as with the combination of PDGF and VEGF. The addition of TGF-β1 did not further improve the outcome.In conclusion, the herein presented brushite–PLGA system effectively controlled the release kinetics and localisation of the three GFs within the defect site resulting in markedly enhanced bone regeneration.

Enchondroma protuberans of the phalanx

Enchondroma protuberans is a rare tumour that rises from an intramedullary enchondroma with an exophytic growth pattern. Although it causes an interesting clinical picture it is benign, and marginal resection of the tumour with bone grafting of the intramedullary defect is curative. We report a case of an enchondroma protuberans of the fifth middle phalanx of the right hand treated by resection, curettage, and autologous bone grafting, with recovery of the normal function of the hand and fingers.