Cement leakage as a possible complication of balloon kyphoplasty--is there a difference between osteoporotic compression fractures (AO type A1) and incomplete burst fractures (AO type A3.1)?

BACKGROUND

Besides the treatment of osteoporotic vertebral compression fractures of AO type A1, balloon kyphoplasty (BKP) is seen as a therapeutic option even in the treatment of incomplete osteoporotic burst fractures (AO type A3.1). However, due to involvement of the posterior vertebral body wall, the risk of cement leakages is considered to be higher. This study focuses on the frequency and pattern of cement leakages in AO type A3.1 fractures compared with osteoporotic compression fractures (AO type A1).

PATIENTS AND METHODS

Retrospective cohort analysis was done of all patients (n = 138) treated by BKP for osteoporotic vertebral fractures (n = 173) between January 2007 and December 2010 in our department. Cement extravasations into three pre-defined anatomical compartments were evaluated on postoperative CT scans of the augmented vertebral bodies, with even minor cement detections beyond the vertebral body's wall being strictly inidicated as leakages. The frequency of cement leakages in relation to the fracture type was statistically analyzed using Pearson's chi-square test. Clinical and radiological follow-up was done 6 weeks, 3 and 6 months postoperatively.

RESULTS

The overall cement leakage rate of BKP in 173 treated osteoporotic vertebral fractures was 30.6%. Cement extravasations were detected in 20.3% of A1.1, 30.5% of A1.2, 37.8% of A1.3, and 39.0% of A3.1 fractures, respectively. There was no statistically significant difference in the leakage rate between A3.1 and all A1 fractures (28.0%; p > 0.05), but between A3.1 and A1.1 fractures (p < 0.05). Intraspinal cement extravasations, being the most dangerous, were seen in 25.5% of all leakages (n = 53), whereas in relation to the total number of treated fracture types, there were only 5.1% intraspinal leakages in A1.1, 5.6% in A1.2, 10.9% in A1.3, and 9.8% in A3.1 fractures. Two of 13 patients with intraspinal leakages and 1 patient with a paraaortal anterolateral cement extravasation needed surgical revisions. Two pulmonary PMMA cement embolisms were detected, but without any clinical consequences. None of the patients with cement leakages during BKP suffered from new neurological deficits.

CONCLUSIONS

Cement leakages remain a problem in BKP. Although there was no significant difference between AO type A3.1 and all A1 fractures, subgroup analysis revealed a statistically significant higher risk of cement extrusions in A3.1 compared to A1.1 fractures. None of the affected patients showed new neurological deficits due to cement extravasations. Still, balloon kyphoplasty can be considered a safe procedure, even in the treatment of painful osteoporotic vertebral fractures of AO type A3.1.