With the increase in the elderly population in China, an increasing number of aged patients with degenerative lumbar disease (DLD) require surgical treatment. DLS is a type of spondylolisthesis with an intact neural arch. The treatment objectives of surgery include neural decompression, motion segment stabilization, intervertebral disc height reconstruction and sagittal balance restoration[1-2][9-12]. Spondylolytic segment stabilization relies on fusion through an anterior, a posterior or a combined approach[12-13]. The PLF technique has gained reliability and popularity for DLS. Posterolateral fusion or intervertebral interbody fusion immediately and rapidly reconstructs a biomechanically stable spine, thereby increasing the chance of fusion[14-16]. However, in elderly patients, it is a challenge to perform spine surgery because of the increasing presence of medical diseases and surgical complications. Furthermore, reoperation is an unplanned event for these patients, their families and surgeons, which results in additional perioperative complications, including death and potential medical risks or medical disputes. It is important for surgeons to identify risk factors in order to make better preoperative decisions and evaluate the surgical procedures to avoid unplanned reoperations.
Several previous studies reported reoperation following primary lumbar surgery for degenerative conditions and indicated that the revision rates were 14.0% in the 1997 to 2000 cohort and 12.4% in the 1990 to 1993 cohort. Ghogawala demonstrated that the reoperation rate after only decompression for DLS at 1 year postoperatively was 15%, while Blumenthal reported a rate of 37.5% at a mean follow-up of 3.6 years. The reoperation rate found in the present study was nearly the same as that in previous studies: the reoperation rate for only decompression at the 1-year follow-up was 10.8%, and the rate increased to 29.7% at 5 years postoperatively and to 33.4% at the final follow-up[20-21]. Another report demonstrated that the cumulative reoperation rate was 6.1% at 1 year, 8.5% at 2 years, 15.2% at 3 years, 17.7% at 5 years, and 23.3% at the final follow-up. In contrast to the studies mentioned above, in our study, the reoperation rate of DLS was 3.0%, which was lower than the rates found in previous studies. The reason for the lower reoperation rate in our study may be that we only reported reoperation during patients with one-level or two-level DLS.
Elderly patients have commonly been considered to be at a higher risk of postoperative complications from DLS than younger patients. An approximately 80% complications rate has been document in patient who undergo surgery for DLS[23-27]. In the study by Okuda, postoperative complications were found in 16% of elderly patients after PLIF with pedicle screw placement. In our series, the major reasons for reoperation were wound infection, screw misplacement, neurological deficit, nonunion, and screw fracture, which were similar to previous reports. Therefore, a better understanding of the complications, risk factors and unplanned reoperation rate is helpful for improve surgical outcomes.
In our study, higher BMI, DM, more bleeding and female sex predicted the occurrence of wound infection, which other studies have previously reported. Deep postoperative wound infection will significantly impact the surgical outcomes of DLS and will have an important influence on the surgical plan, which requires revision surgery with implant removal if necessary. This complication also increases the cost of hospitalization and nursing. Additionally, spine surgeons should pay more attention to improving surgical training and may need more help from multiple disciplinary teams (MDTs).
Another common reason for unplanned reoperation was screw displacement in the study. Complications related to screw displacement in spinal surgery are common and often result in spinal cord and nerve root injuries as well as dural lesions that require immediate revision surgery. Fortunately, all neurological defects in the patients after reoperation were alleviated and returned to normal at the final follow-up. Additional spine courses or navigation systems may help reduce the rate of screw displacement. Additionally, we found that patients who underwent posterolateral fusion procedures had a higher incidence of nonunion and a higher rate of unplanned reoperation. The results showed that a detailed preoperative plan and strict follow-up may work for patients with DLS when indicated for surgical treatment.