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Bilateral Pedicle Fractures Following Anterior Dislocation of the Polyethylene Inlay of a ProDisc® Artificial Disc Replacement: A Case Report of an Unusual Complication

Mathew, Philip, MRCS*; Blackman, Mark, FRCS*; Redla, Sridhar, MD, FRCR; Hussein, Ahmed A., FRCS*

doi: 10.1097/01.brs.0000164135.03844.b6
Case Report

Study Design. An unusual complication resulting from an artificial disc replacement for lumbar degenerative disc disease and its treatment are reported

Objective. To describe the clinical circumstance, radiologic findings, treatment, and outcome of bilateral pedicle fractures associated with dislocation of the polyethylene inlay of a ProDisc® replacement at L5/S1 level.

Summary of Background Data. To the authors’ knowledge, no published reports in the English literature have described bilateral pedicle fractures following a single level artificial lumbar total disc replacement.

Methods. A 30-year-old male underwent a ProDisc® total disc replacement at L5/S1 level for discogenic pain. Six-week postoperative assessment showed improvement in the visual analog and Oswestry scores. Assessment at 18 weeks postoperatively for acute pain revealed an anterior slip of the superior plate component, and computerized tomography showed bilateral pedicle fractures of the fifth lumbar vertebra. At surgery, the poly insert was found to have dislocated anteriorly. A salvage interbody fusion was then performed using the stand-alone anterior lumbar interbody fusion cage.

Results. The most recent review confirmed radiologic evidence of fusion with improvement in the subjective evaluation scores

Conclusions. We hypothesize that the current implant design in which the contribution to lordosis angle is purely from the superior component may be responsible for the reported complication. We suggest that dividing the contribution equally between both endplates might increase the stability, and this has been discussed with the manufacturers.

With an increasing demand for better solutions, total disc replacement is fast emerging as an acceptable and viable alternative to fusion for the treatment of lumbar degenerative disc disease. With increasing use, more complications are becoming apparent. Strict patient selection criteria and subtle modifications to the implant design are suggested to ensure favor for its continued use in the future.

From the Departments of *Orthopaedics and †Radiology, Princess Alexandra Hospital, Harlow, United Kingdom.

Acknowledgment date: May 20, 2004. First revision date: September 24, 2004. Acceptance date: September 29, 2004.

The legal regulatory status of the device(s)/drug(s) that is/are the subject of this manuscript is not applicable in my country.

No funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.

Address correspondence and reprint requests to Philip Mathew, MRCS, Trauma Fellow, Department of Orthopaedics, Princess Alexandra Hospital, Hamstel Road, Harlow CM20 1QX, United Kingdom; E-mail:

© 2005 Lippincott Williams & Wilkins, Inc.