Preliminary report on value of Wallis interspinous device for back pain following microdiscectomy: A prospective cohort study

Abstract

Background: Postoperative back pain is a common complaint following microdiscectomy. The Wallis implant, an interspinous process device, is effective against mechanical low back pain due to spinal instability following discectomy. The present study aims to evaluate the value of the Wallis implant with microdiscectomy compared with microdiscectomy alone. Materials and Methods: Twenty patients were enrolled between June 2016 and August 2019. All patients received complete radiography and completed a questionnaire before and 1, 3, 6, and 12 months after surgery. Clinical outcomes were evaluated using the visual analogue scale (VAS) for back pain and Oswestry Disability Index (ODI). Radiologic outcomes were posterior disc height, foraminal height, foraminal area, segmental angle, and range of motion in flexion and extension views. Results: The Wallis group contained six male and three female patients (mean age 45.7 ± 13.3 years, range 20–61 years), and the control group comprised three male and eight female patients (mean age 47.6 ± 7.5 years, range 34–58 years). All patients had clinical improvements in VAS score and ODI after microdiscectomy alone or with the placement of the Wallis implant. The Wallis group had more favorable mean VAS score and ODI at the 1-, 3-, 6-, and 12-month follow-ups compared with the control group. However, the mean VAS score of the Wallis group was significantly lower than that of the control group only at postoperative month 6 (P = 0.012), whereas the mean ODI in the Wallis group was significantly better than that of the control group only at postoperative months 1 (P = 0.036) and 12 (P = 0.042). Although greater posterior disc height, foraminal height, and foraminal area were observed in the Wallis group, especially in the extension view, the difference in comparison with the control group was not significant. Conclusion: Our limited results indicate that the Wallis implant may reduce postoperative low back pain (VAS score) and improve quality of life (ODI) following microdiscectomy. However, the difference between microdiscectomy alone and microdiscectomy with the Wallis implant was not consistently significant throughout the 12 months of follow-up, regardless of the maintenance of radiologic outcomes.

Keywords

• interspinous process device
• microdiscectomy
• postoperative back pain
• primary herniated intervertebral disc
• wallis implant