Results after Lumbar Discectomy for Herniated Disc in Worker's Compensation Patients: more than 15 Years of Follow- up

Abstract

Introduction Published literature has identified worker's compensation population to have worse results after lumbar discectomy for herniated disc compared with general population. However the advantage of complete follow-up due to its captive population is well know. This study aims to evaluate lumbar discectomy outcomes, prognostic factors and recurrence rate after more than15 years of follow-up. Material and Methods A retrospective review of 50 worker's compensation patients operated consecutively between 1997–1998 in Hospital del Trabajador for primary herniated lumbar disc was performed. Electronic medical records analysis was conducted until June 2015. Primary outcomes were surgical complications, sick leave, return to work, work compensation, chronic postoperative low back pain and reoperation for recurrent lumbar disc herniation. Statistical analysis looking for prognostic factors in lumbar discectomy evolution was realized. Results We found 44 men and 6 women with a mean age of 36.5 (22–66) years. One hundred percent follow-up was achieved with a mean time of 18 (17.5–18.5) years. Most patients were light workers (58%). Lumbar herniated discs were mostly located at L5-S1 ( n = 35) followed by L4-L5 ( n = 12). 74% were posterolateral disc herniations and 22% were central. Mean preoperative, postoperative and total sick leave was 37.9 (1–109), 57.7 (28–175) and 95.6 (35–203) days respectively. An intraoperative complication rate of 2% was seen, while no infectious complications were reported. All patients returned to work, most of them to the same work (88%). 10% received work compensation. During follow up, 32% (16/50) required a new period of sick leave with a mean sick free time of 64.4 (4–135) months. 8 of these were due to a new episode of low back pain. The rest were 6 recurrent disc herniations and 2 other level disc herniations that required new surgery. At 5, 10 and more than 15 years of follow-up recurrence rate was 8%, 12% and 12% respectively, while chronic low back pain was 8%, 10% and 12% respectively. Psychological disorders found in 18% patients were associated with longer sick leave (62.8 versus 56.6 days. p < 0.05) and higher need of work compensation (33% versus 4.9%, p < 0.05). Patients with preoperative infiltrations (33/50) required more new periods of sick leave (33% versus 5.9%, p < 0.05). Age, type of work, previous low back pain episodes, disc herniation characteristics and preoperative sick leave showed no statistically significant association with postoperative evolution. Conclusion As found in previous study, the presence of physiological disorders, also known as non-organic symptoms, and preoperative infiltrations were associated with worse results after lumbar discectomy. This manifested as longer sick leave periods and higher need of work compensation. Age, type of work, disc herniation characteristics and preoperative sick leave did not represent bad prognostic factors. Disc herniation recurrence rate increased from 8% at 5 years of follow-up to 12% at 10 and over 15 years of follow-up. This recurrence rate is similar to the one reported in literature. Ten percent of postoperative chronic low back pain at 10 years and 12% with more than 15 years of follow-up was observed.