BACKGROUND: Injectable artificial bone composite has been reported to consider as a moulding filler of vertebrae at the histology level; however, the therapeutic effect needs to be further studied at the level of axial pressure capacity. OBJECTIVE: To explore the axial pressure capacity of dogs with thoracolumbar fractures treated by injectable artificial bone composite. DESIGN, TIME AND SETTING: A randomized controlled animal experiment was performed at the Animal Laboratory of Shenzhen Longgang Central Hospital from September 2008 to January 2009. MATERIALS: Type I and type II vertebral pedicle screw systems were provided by Tianjin Zhengtian Medical Device Company Limited; injectable artificial bone composite, which was made of coral-hydroxylapatite compound, recombinant human bone morphogenetic protein-2 (Academy of Military Medical Sciences), and 2% chitosan solution (the Second Military Medical University of Chinese PLA and Shanghai Qisheng Biomaterials Institute), was manufactured according to the methods provided by Yin et al. METHODS: A total of 20 1-year-old healthy dogs were randomly divided into treatment and control groups with 10 dogs in each group. The model of those dogs with thoracolumbar fractures was made by imitating falling accidents; thereafter, the dogs in the treatment group were treated with vertebral pedicle screw system internal fixation and vertebroplasty by filling the injured vertebrae with injectable artificial bones. The control group was treated with vertebral pedicle screw system internal fixation alone. MAIN OUTCOME MEASURES: The maximum pressure intensity of injured vertebra, upper and lower vertebra at vertebral body center was detected using micro-computer pressure testing system after three months. RESULTS: The maximum pressure intensity at vertebral body center was not significant differences in the treatment group (100% cases) between injured vertebral body and its neighboring vertebral body, and axial loading was recovered. While that of 60% cases in the control group was significantly different (P