RESUMEN
INTRODUCTION: Nucleus arthroplasty is a motion preservation technology in which the degenerated nucleus pulposus is replaced during a surgical intervention. MATERIAL AND METHODS: Ten patients with degenerative disc disease (DDD) were selected based on a sampling of patients who met the inclusion criteria of the Spine Service, National Rehabilitation Institute, from August 2006 to January 2007. The PDN-Hydraflex device was applied to them using a retroperitoneal anterolateral approach. At the 2-year follow-up visit a clinical assessment (VAS, Oswestry, SF-12, and physical exam), X-ray studies and MRI were performed. An MRI was taken at two years to document degenerative changes by comparing it with the postoperative MRI. Degenerative changes were assessed using the Modic scale. RESULTS: Five males and 5 females were included; mean age was 35.1 years (22-51 years). There was no subsidence at the 2-year postoperative follow-up (p = 0.79), with clinical improvement in the Oswestry scale (p = 0.005) and the quality of life according to the SF-12 questionnaire (p = 0.005). There was significant decrease in lumbar pain (p = 0.007) and in right pelvic limb pain (p = 0.036). Ninety percent of patients had Modic changes. CONCLUSIONS: The use of the PDN-HydraFlex partial nucleus replacement system resulted in improvement of the patients' clinical conditions at the 2-year follow-up, without migration or device-related adverse reactions. Disc height and mobility were maintained at 2 years.