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

• Published in: European spine journal 2011-02, Vol.20 (2), p.280-288
• Main Authors: Sur, Yoo-Joon, Kong, Chae-Gwan, Park, Jong-Beom
• Format: Article
• Language: English
• Subjects: Adult; Diskectomy - instrumentation; Diskectomy - mortality; Female; Humans; Intervertebral Disc Displacement - mortality; Intervertebral Disc Displacement - surgery; Kaplan-Meier Estimate; Laminectomy - instrumentation; Laminectomy - mortality; Lumbar Vertebrae - surgery; Male; Medicine; Medicine & Public Health; Middle Aged; Neurosurgery; Original; Original Article; Prosthesis Implantation - mortality; Spinal Stenosis - mortality; Spinal Stenosis - surgery; Surgical Orthopedics; Survival Rate; Treatment Outcome
• ISSN: 0940-6719; 1432-0932
• DOI: 10.1007/s00586-010-1599-z

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 tw