Lumbar disk replacement failures: review of 29 patients and rationale for revision

The Charité III (DePuy Spine, Inc, Raynham, Massachusetts) and ProDisc II (Synthes Spine, West Chester, Pennsylvania) artificial disk replacements were approved for use by the United States Food and Drug Administration in October 2004 and January 2006, respectively. The purpose of this study was to retrospectively review 29 patients receiving either disk replacement who presented with complications to the University of California Irvine Spine Center. Specifically, patient outcome data from the Oswestry Disability Index (ODI) and the SF-36 were analyzed. The probable sources of pain were determined based on diagnostic facet and nerve root injections, single photon emission computed tomography bone scans, computed tomography scans, magnetic resonance imaging scans, flexion extension radiographs, patient history, and physical examination and direct surgical observation when possible. Results suggested that the main source of pain is facet degeneration and fractures in this area due to flawed biomechanics of disk replacement design. Oswestry Disability Index and SF-36 scores exhibited marked disability with a large improvement in all scores after revision surgery. This difference was statistically significant for the ODI and the SF-36 MCS (mental), but not for the SF-36 PCS (physical). A successful outcome in the revised patients was achieved completely in the majority, and only partially in some, by a solid fusion after meticulous and complete facet excision and correction of the segmental deformity.