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Subsequent vertebral fractures following kyphoplasty: association with intradiscal PMMA leakage as cause of adjacent fracture 2007

Interventional Spine

Farbod Nasseri, M.D.
Hani A. Haykal, M.D., Non ASSR Member

Scientific Paper

Purpose

Patients with osteoporotic vertebral fracture often return with additional vertebral fractures after polymethylmethacrylate (PMMA) Kyphoplasty. There is conflicting data regarding the incidence of subsequent adjacent fractures due to intra-discal PMMA leakage or increased vertebral rigidity after vertebral augmentation.[1-2] The purpose of this study is to evaluate the frequency of adjacent and remote fractures after Kyphoplasty, and to determine any possible patterns of recurrent fractures and intra-discal PMMA leakage.

Methods & Materials

We retrospectively reviewed 731 osteoporotic vertebral fractures treated with kyphoplasty in 441 patients (71% female) during 667 treatment sessions between October 2001 and October 2006. Fractures were diagnosed on the basis of MRI or bone scan. 60 patients, with 110 new fractures returned for vertebral augmentation by Kyphoplasty. The incidences of new adjacent and remote vertebral fractures were determined. The incidence of adjacent intradiscal PMMA leakage was evaluated since that was felt to be a significant factor in recurrent fractures. Chi square and Fisher's exact test analysis was used to compare the observed proportion of occurrence of the adjacent fracture in both patients with and without intra-discal leak of the PMMA. Our null hypothesis was that the presence of intra-discal leakage would cause occurrence of the adjacent fracture of previously treated vertebra with Kyphoplasty.

Results

110 new vertebral fractures (median number of new fractures=2, range 1-6) occurred during our follow up period from October 2001 to October 2006, of which 68 (62%) vertebral fractures occurred immediately adjacent to previously treated vertebra (39 at adjacent-above levels, 29 at adjacent-below levels) and 42 (38%) vertebral fractures occurred in remote locations, separated by at least 1 vertebral body away from previously treated vertebra. Of the 68 adjacent fractures 18 (15%) noted to be adjacent to an intra-discal leak of the PMMA and 6 (9%) were located opposite to the end plate adjacent to the intra-discal leakage. These 6 fractures all occurred below a previously treated vertebra where the intra-discal leakage was to the disc above the first treated level (P< 0.01). No significant association between the presence of minimal intra-discal leakage and occurrence of the adjacent fracture was found. Subjective evaluation of intra-discal leak revealed that 30 leaks were noted to be minimal leaks to the annulus, 2 medium size leaks in to the annulus and 1 large leak penetrated to the nucleus pulposus.

Conclusion

Small intra-discal annular leaks of PMMA after Kyphoplasty do not appear to be a significant factor inducing adjacent fractures. Our results indicate that the risk of recurrent fracture after Kyphoplasty is less than that previously reported for Vertebroplasty.

References

References:

1- Lin EP, Ekholm S, Hiwatashi A, Westesson PL., Vertebroplasty: cement leakage into the disc increases the risk of new fracture of adjacent vertebral body.AJNR Am J Neuroradiol. 2004 Feb;25(2):166-7.
2- Fribourg D, Tang C, Sra P, Delamarter R, Bae H. Incidence of subsequent vertebral fracture after kyphoplasty. Spine. 2004 Oct 15;29(20):2270-6; discussion 2277.

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