Effect of Bone Cement Volume Fraction on Adjacent Vertebral Fractures after Unilateral Percutaneous Kyphoplasty.

STUDY DESIGN: A retrospective study.

SUMMARY OF BACKGROUND DATA: Complications of the bone cement used in vertebroplasty and kyphoplasty procedures have received increasingly more attention, especially for bone cement volume.

OBJECTIVE: The aim of the study was to retrospectively assess the relationship between bone cement volume fraction and adjacent vertebral fracture (AVF) after unilateral percutaneous kyphoplasty (PKP).

MATERIALS AND METHODS: Between 2006 and 2011, 495 patients with single level osteoporotic vertebral compression fracture (OVCF) were surgical treated by unilateral PKP and had completed 12-month follow-up in our hospital. According to the new OVCF, they were divided into three groups: AVF group, non-AVF group and normal group (who were not new OVCF). Based on the value of the plain radiography, the cement volume fraction for the vertebral body was calculated, and cement leakage, bone mineral density (BMD), visual analog scale (VAS), and Cobb angle of preoperative and postoperative were analyzed.

RESULTS: During the follow-up, 110 (22.2%) patients had new OVCF, and others were normal (n=385). 52 cases were AVF, and 58 were non-AVF. The cement volume fraction of AVF group, non-AVF group and normal group were 32.5%±5.5%, 27.3%±1.8%, and 27.1%±2.6%, respectively. The 95% confidence interval of volume fraction were (31.0, 34.1), (26.8, 27.7), and (26.9, 28.5), respectively. The AVF group showed higher cement volume fraction in three groups (P<0.05), and there were no significant difference between non-AVF and normal group (P>0.05). There were 19 (36.5%) patients with cement leakage in AVF group, 12 (20.7%) in non-AVF group, and 68 (17.7%) in normal group. The AVF group showed higher cement leakage (P<0.05). Compared with AVF group and normal group, non-AVF group had lower BMD in preoperation. All groups reported significantly improved VAS scores and Cobb angle on the day of surgery. However, there were no significant difference between the three groups.

CONCLUSIONS: Unilateral PKP is an effective and safe procedure for patients with OVCF. However, cement volume should be determined in terms of the vertebral body fraction to obtain a favorable outcome. The risk of AVF and cement leakage will increase obviously with the cement volume fraction increased. We recommend that a bone cement volume fraction of about one-fourth is suitable for unilateral PKP.