Complications and radiographic changes after implantation of interspinous process devices: average eight-year follow-up

PURPOSE: This study aims to evaluate complications, clinical outcomes, and radiographic results following Coflex implantation. METHODS: We retrospectively studied 66 patients who had decompressive surgery combined with Coflex implantation to treat lumbar spinal stenosis. All imaging data were collected and examined for imaging changes. Clinical outcomes, included Oswestry Disability Index (ODI), back and leg visual analog scale (VAS) scores, were evaluated before surgery, six months after surgery and at the last follow-up. The number of complications occurring after five years of follow-up was counted. All reoperation cases were meticulously recorded. RESULTS: 66 patients were followed up for 5–14 years. The VAS and ODI scores were significantly improved compared with baseline. Heterotopic Ossification (HO) was detectable in 59 (89.4%). 26 (39.4%) patients had osteolysis at the contact site of Coflex with the spinous process. Coflex loosening was detected in 39 (60%) patients. Spinous process anastomosis was found in 34 (51.5%) patients. There was a statistically significant difference in the VAS score of back pain between patients with and without spinous process anastomosis. Nine cases of lumbar spinal restenosis were observed, and prosthesis fracture was observed in one case. CONCLUSION: Our study identified various imaging changes after Coflex implantation, and majority of them did not affect clinical outcomes. The majority of patients had HO, but osteolysis and Coflex loosening were relatively rare. The VAS score for back pain of these patients was higher if they have spinous process anastomosis. After five-year follow-up, we found lumbar spinal restenosis and prosthesis fracture cases.