STUDY DESIGN: A retrospective study. OBJECTIVES: To evaluate the fixation survival rate and the radiologic prognostic factors of posterior short fusion in thoracolumbar fracture. SUMMARY OF BACKGROUND DATA: Posterior short fusion has the advantage of saving motion segments in spite of high fixation failure rate. The high load-sharing score is well known as a cause of fixation failure, but the effect of osteopenia is not evaluated. MATERIALS AND METHODS: Authors evaluated 27 patients treated surgically with posterior short fusion using pedicle screws as thoracolumbar fractures from 1995 to 1999. The median follow-up was 20.5 months (6-54). The survivorship using Kaplan-Meier method and the radiologic prognostic factors were evaluated. RESULTS: The sagittal index was preoperatively 16.7 dgree (+/-7.9 SD), immediate postoperatively 6.9 dgree (+/-4.6), and at last follow-up 10.6 dgree (+/-6.9). The fixation failures were detected in 4 patients, and the failure time was ranged from 6 months to 11(median 7.5). The overall survival rate was 82.3% at the last follow-up. The significant prognostic variables were load-sharing score, Jikei grade, compression percent and age in uni-variate analysis, but the load-sharing score and Jikei grade were significant prog-nostic factors in multivariate analysis. CONCLUSIONS: In decision to perform posterior short fusion, the load-sharing score and evidence of osteopenia should be consid-ered as a prognostic factors to avoid fixation failure in thoracolumbar fracture.