Objective:To explore the causes and preventive ways of the bone cement leakages in a single balloon cross-midline expansion via unipedicular approach Kyphoplasty for osteoporotic vertebral body compression fractures from April 2003 to January 2008. Methods:Forty-three patients(27 male 16 female) of osteoporotic vertebral body compression fractures(range 65 to 92,average 67.7 years old) were treated with unilateral transpedicular puncture of PKP. The total vertebral body was 66. The bone cement leakages were analyzed of the postoperative X-ray films. The causes, dangerousness and the prevention of the leakages of bone cement were analyzes. Results:Marked or complete pain relief was achieved in all patients. Five vertebral bodies of 66 were showed bone cement leakage(incidence rate was 7.6%). All the patients were followed up for at least 6 months, there were no mal-outcomes. Conclusion:Unilateral transpedicular puncture of percutaneous kyphoplasty(PKP) is a minimally invasive, effective and safe procedure that provides pain relief and stabilization of spinal stability. Bone cement leakages are the main complications in the unilateral transpedicular puncture of Kyphoplasty,as long as choosing the suitable cases, obeying specification of the surgical procedures, the leakages of cement might be avoided.