RESUMO
The etiology of failed degenerative lumbar spine surgery may include a wide array of conditions. There is a group of patients who have recurrence of back pain despite a solid fusion in the absence of any obvious pain generator. Implant removal in those patients is a controversial optional treatment. The purpose of this study was to evaluate the efficacy and safety of implant removal and to determine the possible predictors of its efficacy. Twenty-five patients (10 M, 15 F) with an average age of 44 (18 to 74) were retrospectively evaluated. All patients had prior titanium posterior pedicle screw instrumentation and fusion for lumbar degenerative disorders. Twenty patients with increase in pain during palpation of the operative side underwent a preoperative anesthetic injection at the site of their trigger points. Patients' clinical charts, operative notes, and preoperative x-rays were evaluated. Relief of pain was evaluated by the percent Visual Analog Scale (VAS) pain change due to implant removal. Functional improvement was rated on a five-point scale. Predictors of pain relief were analyzed by using bivariate analysis. A P value <0.05 was considered significant. Average follow-up period was 20 (12 to 37) months. The median time after the index operation and the recurrence of pain was 13.5 (1 to 119) months. VAS decrease after implant removal was 50% (P<0.001). Functional improvement was reported by 84% of patients. One patient developed a superficial infection managed successfully. Bivariate analysis showed that percent VAS change after injection, months free of pain after the index operation, and provocation of pain by palpation were significant predictors for pain relief (P<0.05). Removal of the implant may be an efficient and safe procedure for carefully selected patients and the most consistent predictor of its efficacy is the percent pain relief after the diagnostic injection of the painful operative side.
