Application of bioactive artificial vertebrae of nano-hydroxyapatite and polyamide 66 to anterior approach of osteoporotic thoracolumbar burst fractures / 中国组织工程研究

ABSTRACT

BACKGROUND: During thoracolumbar anterior operation, implant collapse is an important factor for affecting outcome in patients with thoracolumbar fracture. In particular, osteoporotic patients commonly developed implant collapse, nail channel loose, bone disunion, kyphosis deformation. Bioactive artificial vertebrae of nano-hydroxyapatite and polyamide 66 (n-HA/PA66) has good biocompatibility and biological safety and is an ideal substitute for vertebral body bone graft. OBJECTIVE: To investigate the efficacy of the bioactive artificial verteificial vertebrae of nano-hydroxyapatite and polyamide 66 (n-HA/PA66) for osteoporotic thoracolumbar burst fracture. DESIGN, TIME AND SETTING: A retrospective case analysis was conducted at the Department of Spinal Surgery, Affiliated Hospital of Luzhou Medical College from January 2004 to January 2008. PARTICIPANTS: A total of 20 patients with moderate and severe osteoporotic thoracolumbar fracture (6 males and 14 females) aged 51 -82 years, with an average of 69 years were enrolled in this study. There were 17 cases of fresh fracture and 3 cases of old fracture. n-HAyPA66 was produced by the Sichuan Guona Science and Technology Co., Ltd. This artificial vertebral body was in 10-35 mm diameter, 30-100 mm length, circular cylinder shape, 3-12 mm midheaven diameter, 2.5-6.5 mm tubal wall thickness, with the presence of 2 mm holes surrounding the vertebral body. The contact area of the vertebral body was 78.5-176.7 mm2. Fixity was anterior nail plate system (titanium alloy material) produced by Foshan Shitaibao Company. METHODS: Following conventional tracheal intubation and general anesthesia, at right arm recumbent, according to various fracture-involved segments, different regions were incised and treated with anterior decompression, implanted with artificial vertebrae with the bioactive artificial verteificial vertebrae n-HA/PA66 and fixed with steel plate. MAIN OUTCOME MEASURES: Fracture healing and implant loose were observed by radiograph. Cobb angle, the height of damaged vertebral body and spinal cord function score were compared prior to surgery, 3 months following surgery and the last follow-up. RESULTS: All the patients were successfully operated. Bleeding 200-800 mL during surgery and operation time ranged from 2.0 to 3.0 hours. There were 1 case of pulmonary infection and 1 case of delayed wound healing. A total of 20 patients were followed up for 6-42 months (averagely 18 months). Postoperative radiograph review demonstrated that closed vertebral body was healed three to four months. No significant displacement of implant was found. There was less loss of reestablished vertebral body height. Internal fixation position was good, without nail breakdown or internal fixation loose/displacement. At 3 months following surgery, significant differences in Cobb angle, the height of damaged vertebral body and spinal cord function score were detected compared with that before surgery (P < 0.05). No significant difference in postoperative two follow-up was detected (P > 0.05). CONCLUSION: The bioactive artificial vertebrae of n-HA/PA66 can increase the fusion area, reduce local pressure and prevent loosening of implants and sinking into the vertebrae, finally resulting in restoration of vertebral body height.