Experimental study of a 3D-printing technique combined with biphasic calcium phosphates to treat osteonecrosis of the femoral head in a canine model.

OBJECTIVE: This study was aimed to use a digital design of 3D-printing technology to create a surgical navigation template. At the same time, biphasic calcium phosphate (BCP) was applied to treat osteonecrosis of the femoral head (ONFH) in animal models, based on accurate positioning of necrotic lesions in the navigation templates and observation of its therapeutic effect. METHODS: Fifteen healthy adult male and female beagle dogs weighing 20 + 2 kg were randomly divided into three groups (n = 5) after establishing a model of ONFH using the liquid nitrogen freezing method. Each model underwent necrotic lesion creation and BPC implantations on one side of the femoral head and only necrotic lesion creation on the other side of the femoral head. Each group underwent CT examination, gross observation, histological examination and immunohistochemical staining at 6 weeks, 12 weeks and 18 weeks postoperatively. RESULTS: At weeks 6, 12, and 18, CT and gross examination showed that the necrotic area in the experimental group was basically intact and had been completely raised by BCP material. In the control group, there were signs of bone repair in the femoral head, but there were still large bone defects and cavities. At week 18, extensive collapse of the cartilage surface was observed. Through histological examination, in the experimental group at 12 and 18 weeks, a large number of new and reconstructed bone trabeculae containing a large amount of collagen fibres were observed (P < 0.05), while in the control group, there was extensive necrosis of the bone trabeculae without cellular structural areas. Immunohistochemical examination observation: A large number of CD31-positive cells were observed in the experimental group at 6 weeks, gradually decreasing at 12 and 18 weeks (P < 0.05), while a small number of CD31-positive cells were observed in the control group at 18 weeks. CONCLUSION: The 3D-printed navigation template can accurately locate ONFH lesions. Implantation of BCP material can effectively play a supporting role, prevent the collapse of the loading surface, and induce bone formation and angiogenesis to some extent.

Perforator pedicled propeller flaps for soft tissue coverage of lower leg and foot defects.

OBJECTIVE: To investigate the efficiency of perforator pedicled propeller flaps for soft tissue coverage of lower leg and foot defects. METHODS: Twenty patients (12 male, 8 females; mean age 28 years, range, 5-75) with soft tissue defects of the lower leg and foot were retrospectively reviewed. Their defects had been repaired with perforator pedicled propeller flaps from September 2011 to October 2013 and included five cases of injuries caused by spokes, four of infection with postoperative skin necrosis, two of dorsal skin defects caused by heavy objects and nine caused by car accidents. The areas of soft tissue defect were from 2 cm × 8 cm to 10 cm × 20 cm. Fifteen cases had terminal branch of the peroneal artery perforator flaps and five posterior tibia artery perforator flaps, flap size ranging from 5 cm × 11 cm to 12 cm × 28 cm. Color Doppler ultrasound was used to locate all perforator vessels, the calibers of which ranged from 0.8 mm to 1.0 mm. RESULTS: The intraoperative coincidence rate of the color Doppler ultrasound was 96.7%. The donor sites were sutured directly in 12 cases and skin grafted in 8. One case had a venous crisis within 24 h that was treated by removal some sutures and drainage. All cases were followed up for 1-18 months; all flaps survived well and pedicles had a satisfactory appearance. The patients were extremely satisfied with the results for repair. CONCLUSION: Perforator pedicled propeller flaps have the advantages over other pedicle flap of being simple, safe, and effective and not involving vascular anastomosis.