No abstract

Calcium phosphate cement (CPC) is a widely used bone substitute in the clinic; however, the low strength of CPC limits its utilization. In this study, we investigated mechanical influences of chitosan fiber combined with gelatin on CPC, and examined the biocompatibility of the new composite with rat bone marrow stromal cells. Compared to the fiber impregnated in phosphate buffered saline (80.5 MPa), our study showed that tensile strength of chitosan fiber increased 106 and 114% with the impregnation of gelatin at the mass fraction 5 and 10%, although this increase was not statistically significant. It was demonstrated by Fourier transform infrared spectroscopy that the characteristic absorption bands of chitosan were changed with the addition of gelatin. The optimal flexural strength enhancement was obtained when CPC was reinforced with fiber at volume fraction of 30% and gelatin at mass fraction of 5% (maximum: 12.31 MPa). The fiber morphology was more compact when the chitosan fibers impregnated with gelatin at mass fraction of 5 or 10% than chitosan alone. The fracture analysis showed that the new CPC-chitosan fiber-gelatin composite presented many remnants of CPC adhered to fibers. Short minimum essential medium extract test showed no cell growth inhibition after the addition of the new composite. Rat bone marrow stromal cells retain the ability to spread and grow on the composite. Our studies demonstrated that the flexural strength is greatly increased by using CPC incorporated with proper ratio of CF and gelatin. More over, the new composite demonstrated biocompatibility in vitro.

To assess the suitability of clinical application of a new composite consisting of calcium phosphate cement (CPC), chitosan fibre and gelatin, a bilateral supracondyle hole defect (5 mm in diameter) was developed in the femurs of 40 New Zealand white rabbits and filled with either the composite or CPC. Macroscopic, radiological, histological and histomorphometric evaluations were performed at the time points of 1, 3, 6 and 12 months post-operation. New bone formation of the composite group was 46.5 +/- 3.2% within 12 months, while that of the CPC group was 12.4 +/- 2.7% (p < 0.05). No adverse response was found in either group. In addition, it was very interesting that the new bone grew into the implant only in the composite group. By histochemical staining we found that chitosan fibre was surrounded by monocytes and macrophages after 3 months. Overall, our study demonstrated that both CPC and the composite had osteoconductive characteristics and good biocompatibility, but the composite presented superior bioresorbability and a higher rate of new bone formation.

Various synthetic bone substitutes are not suitable for reconstructing critical-size bone defects. This study tested whether a bioglass-β-tricalcium phosphate (β-TCP) monoblock is effective for repairing critical-size segmental bone defects if combined with a vascularized periosteal flap and bone morphogenetic protein (BMP)-2. A femoral osteotomy with a gap size of 20 mm was created and stabilized using a plate in 40 rabbits.The defect was left untreated (group A) or repaired using a monoblock (group B), a monoblock with a vascularized periosteal flap (group C), or a monoblock with a vascularized periosteal flap and BMP-2 (group D). Bone regeneration, vascularization and monoblock degradation were analyzed after four and eight weeks using x-ray, hematoxylin-eosin, CD34 immunohistochemical and Masson's trichrome staining observation and histometric evaluation. The radiographic grading score showed a time-dependent increase from weeks 4 to 8. At 8-week postoperative, the total new regenerated bone in groups C and D was 20.0 ± 0.3 and 55.5 ± 8.0 mm , respectively, which was significantly greater than in group B. Conversely, group D showed less residual monoblock than did group C. An increase in microvessel density was also observed in groups C and D compared with group B at 4 and 8 weeks postoperative, respectively. This study suggests that bioglass-β-TCP monoblock alone exhibits poor potential to repair a 20-mm femoral defect. However, supplementation with a vascularized periosteal flap and BMP-2 led to effective vascularization and reliable bone regeneration throughout the monoblock, with concordant material degradation in a timely manner. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2148-2156, 2018.

No abstract

A total of eight cases with multiple skin defects of the hand and digits were resurfaced using a free iliac flap. The lesions involved both the hand and multiple digits in five patients and multiple digits in three patients. The average skin flap size was 89.3 cm(2). In three, a piece of of vascularized iliac bone was included. There was no flap loss. Flap debulking was performed in five patients at 10-12 weeks post-surgery during the operation for flap separation and inset. Secondary flap debulking was performed in one patient at 6 months post-surgery. The average static 2-point discrimination was 15.4 mm in five patients, whereas the remaining patients only exhibited sensation to pressure. This procedure may require additional refinement; however, the free iliac flap with technical refinements is a viable option for the treatment of multiple skin defects of the hand and digits.

Chimeric iliac osteocutaneous flaps may be a useful alternative for treating complex metacarpal defects because they yield a thinner skin paddle and less bulky bone segment than traditional flaps.

SUMMARYObjective: To compare the mechanical e ects of metatarsal deÿcit and its reconstruction with ilium, ÿbula and scapula on foot function using three-dimensional (3-D) ÿnite element analysis.Methods: Deÿcits of the ÿrst to the third metatarsal bone and the fourth to the ÿfth metatarsal bone, and their reconstructions with ilium, ÿbula and scapula, respectively, were simulated by a 3-D foot model. The peak displacement and the peak stress were deÿned as indexes to estimate foot function.Results: It was found that foot function was a ected primarily by the deÿcit of the ÿrst to the third metatarsal bone. In comparison with the intact healthy foot, the peak displacement and the peak stress of the whole deÿcit of the ÿrst to the third metatarsal bone increased by 215 and 212%, respectively, while those of the half deÿcit increased by 165 and 205%, respectively. For the whole and the half deÿcit of the fourth to the ÿfth metatarsal bone, the values of the two indexes increased by 144 and 109%, and 137 and 103%, respectively. After reconstruction, the results showed that the stress-concentrated regions dispersed relatively, especially in heel, metatarsal heads and reconstructive bone block. The maximum displacement and stress of the deÿcit rebuilt by ilium were the minimums in comparison with the reconstructions with ÿbula and scapula.Conclusion: The reconstructed multi-metatarsal deÿcit can be analysed by ÿnite element method. The ilium was the preferred reparation material for the bone deÿcit.