Survivorship analysis of 150 consecutive patients with DIAM? implantation for surgery of lumbar spinal stenosis and disc herniation

摘要

Recently, the Device for Intervertebral Assisted Motion (DIAM?) has been introduced for surgery of degenerative lumbar disc diseases. The authors performed the current study to determine the survivorship of DIAM? implantation for degenerative lumbar disc diseases and risk factors for reoperation. One hundred and fifty consecutive patients underwent laminectomy or discectomy with DIAM? implantation for primary lumbar spinal stenosis or disc herniation. The characteristics of the 150 patients included the following: 84 males and 66 females; mean age at the time of surgery, 46.5?years; median value of follow-up, 23?months (range 1–48?months); 96 spinal stenosis and 54 disc herniations; and 146 one-level (115, L4–5; 31, L5–6) and 4 two-level (L4–5 and L5–6). In the current study, due to lumbosacral transitional vertebra (LSTV) L6 meant lumbarization of S1 and this had a prominent spinous process so that the DIAM? was implanted at L5–6. Reoperations due to any reasons of the DIAM? implantation level or adjacent levels were defined as a failure and used as the end point for determining survivorship. The cumulative reoperation rate and survival time were determined via Kaplan–Meier analysis. The log-rank test and Cox regression model were used to evaluate the effect of age, gender, diagnosis, location, and level of DIAM? implantation on the reoperation rate. During a 4-year follow-up, seven patients (two males and five female) underwent reoperation at the DIAM? implantation level, giving a reoperation rate of 4.7%. However, no patients underwent reoperation for adjacent level complications. The causes of reoperation were recurrent spinal stenosis (n?=?3), recurrent disc herniation (n?=?2), post-laminectomy spondylolisthesis (n?=?1), and delayed deep wound infection (n?=?1). The mean time between primary operation and reoperation was 13.4?months (range 2–29?months). Kaplan–Meier analysis predicted an 8% cumulative reoperation rate 4?years post-operatively. Survival time was predicted to be 45.6?±?0.9?months (mean?±?standard deviation). Based on the log-rank test, the reoperation rate was higher at L5–6 (p?=?0.002) and two-level (p?=?0.01) DIAM? implantation compared with L4–5 and one-level DIAM? implantation. However, gender (p?=?0.16), age (p?=?0.41), and diagnosis (p?=?0.67) did not significantly affect the reoperation rate of DIAM? implantation. Based on a Cox regression model, L5–6 [hazard ratio (HR), 10.3; 95% CI, 1.7–63.0; p?=?0.01] and two-level (HR, 10.4; 95% CI, 1.2–90.2; p?=?0.04) DIAM? implantation were also significant variables associated with a higher reoperation rate. Survival time was significantly lower in L5–6 (47 vs. 22?months, p?=?0.002) and two-level DIAM? implantation (46 vs. 18?months, p?=?0.01) compared with L4–5 and one-level DIAM? implantation. The current results suggest that 8% of the patients who have a DIAM? implantation for primary lumbar spinal stenosis or disc herniation are expected to undergo reoperation at the same level within 4?years after surgery. Based on the limited data set, DIAM? implantation at L5–6 and two-level in patients with LSTV are significant risk factors for reoperation...