Entangled titanium fibre balls combined with nano strontium hydroxyapatite in repairing bone defects

Abstract

Objective: To investigate the effect of entangled titanium fibre balls (ETFBs) combined with nano strontium hydroxyapatite (nano-Sr-HAP) on the repair of bone defects in vivo.

Materials and methods: Twenty-four 6-month-old, specific pathogen-free, male Sprague-Dawley rats were used. Drill defects were created in bilateral femoral condyles. ETFBs combined with nano-Sr-HAP were selected randomly from 72 samples and implanted into the femoral bone defects of left legs, which served as the experimental group, while ETFBs without nano-Sr-HAP were implanted into right legs for comparison. The bone defects on both sides were X-rayed. The anteroposterior positions and histological procedures and evaluations of each sample were performed at 1, 2, 4 and 8 weeks post-surgery.

Results: Histological results showed that the ETBs allowed new bone to grow within their structure. Additionally, an increase in new bone was seen on the nano-Sr-HAP side compared to the control side. The results of histomorphometric analysis confirmed that the new bone formation on the left side gradually increased with time. There was a statistical increase in new bone at 2, 4 and 8 weeks, and the differences between the two sides were statistically significant at weeks 4 and 8 (p < 0.05 for all comparisons).

Conclusion: The results showed that ETFBs possess a unique 3-dimensional interconnective porous structure and have excellent biocompatibility, cell affinity and osteoconductivity, which makes them useful as scaffold materials for repairing bone defects. On the other hand, nano-Sr-HAP improved the bone defect-repairing capacity of the ETFBs, which showed osteoinductive properties.

Fig. 1

Macroporous structure of the ETFBs.

Fig. 2

Combination image of undecalcified sections on the sagittal plane of the femoral condyle. The arrow indicates the ETFBs. Picrofuchsin (Van Gieson) staining. Original magnification ×50.

Fig. 3

Typical interspace size distribution of the ETFBs.

Fig. 4

X-ray at 1, 2, 4 and 8 weeks post-surgery. L = Experimental group (ETFBs + Sr-HAP); R = control group (ETFBs alone).

Fig. 5

Photomicrograph of the experimental group at 1 (a), 2 (b) and 4 weeks (c, d) post-surgery. e, f Photomicrographs of the control group at 4 weeks post-surgery (note: these images were taken at the edge). Ti = Titanium fibre; F = nano-Sr-HAP; NB = new bone. Picrofuchsin (Van Gieson) staining. Original magnification ×50 (a, b), ×100 (c, e) and ×400 (d, f).

Fig. 6

Photomicrographs of the experimental (a, b) and control (c, d) groups at 8 weeks post-surgery. a Abundant bone formation was apparent inside the ETFBs. b Typical osteoid (or bone-like) structures were observed, i.e. osteocytes were embedded in a tissue matrix. c Bone formation could be observed inside the ETFBs. d Fibrous tissue existed between the new bone and the titanium fibres. Ti = Titanium fibre; NB = new bone. Picrofuchsin (Van Gieson) staining. Original magnification ×100 (a, c) and ×400 (b, d).