Comparison of pedicle screw–based dynamic stabilization and fusion surgery in the treatment of radiographic adjacent-segment degeneration: a retrospective analysis of single L5–S1 degenerative spondylosis covering 4 years

Abstract

<jats:sec> <jats:title>OBJECTIVE</jats:title> <jats:p>Pedicle screw–based dynamic spinal stabilization systems (PDSs) were devised to decrease, theoretically, the risk of long-term complications such as adjacent-segment degeneration (ASD) after lumbar fusion surgery. However, to date, there have been few studies that fully proved that a PDS can reduce the risk of ASD. The purpose of this study was to examine whether a PDS can influence the incidence of ASD and to discuss the surgical coping strategy for L5–S1 segmental spondylosis with preexisting L4–5 degeneration with no related symptoms or signs.</jats:p></jats:sec> <jats:sec> <jats:title>METHODS</jats:title> <jats:p>This study retrospectively compared 62 cases of L5–S1 segmental spondylosis in patients who underwent posterior lumbar interbody fusion (n = 31) or K-Rod dynamic stabilization (n = 31) with a minimum of 4 years' follow-up. The authors measured the intervertebral heights and spinopelvic parameters on standing lateral radiographs and evaluated preexisting ASD on preoperative MR images using the modified Pfirrmann grading system. Radiographic ASD was evaluated according to the results of radiography during follow-up.</jats:p></jats:sec> <jats:sec> <jats:title>RESULTS</jats:title> <jats:p>All 62 patients achieved remission of their neurological symptoms without surgical complications. The Kaplan-Meier curve and Cox proportional-hazards model showed no statistically significant differences between the 2 surgical groups in the incidence of radiographic ASD (p &gt; 0.05). In contrast, the incidence of radiographic ASD was 8.75 times (95% CI 1.955–39.140; p = 0.005) higher in the patients with a preoperative modified Pfirrmann grade higher than 3 than it was in patients with a modified Pfirrmann grade of 3 or lower. In addition, no statistical significance was found for other risk factors such as age, sex, and spinopelvic parameters.</jats:p></jats:sec> <jats:sec> <jats:title>CONCLUSIONS</jats:title> <jats:p>Pedicle screw–based dynamic spinal stabilization systems were not found to be superior to posterior lumbar interbody fusion in preventing radiographic ASD (L4–5) during the midterm follow-up. Preexisting ASD with a modified Pfirrmann grade higher than 3 was a risk factor for radiographic ASD. In the treatment of degenerative diseases of the lumbosacral spine, the authors found that both of these methods are feasible. Also, the authors believe that no extra treatment, other than observation, is needed for preexisting degeneration in L4–5 without any clinical symptoms or signs.</jats:p></jats:sec>

Lumbar Stabilization with DSS-HPS® System: Radiological Outcomes and Correlation with Adjacent Segment Degeneration

“…This kind of trend has been previously reported by Schaeren et al: they found a statistically significant decrease of ADH (p = 0.02) and PDH (p = 0.05) with Dynesys ® compared to pre-surgery values at 2 years of follow up and then, after 4 years, these values seems to stabilize [48]. The conflicting results that have been reported in numerous studies using different dynamic systems are summarized in Table 3 [21,33,43,[49][50][51][52][53][54][55]. Yu et al compared 60 patients at 3 years of follow-up divided into two groups (Dynesys ® vs. PLIF), finding a significant decrease in ADH in the group operated with Dynesys ® (p < 0.05), while an increase significant (p < 0.05) of PDH was observed in both groups [33].…”

“…Since the studies related to the DSS-HPS ® system focused mainly on clinical-rather than radiologicalresults, it is difficult to make a direct comparison with other series. Currently, there is no a single and validated criterion in the literature to define the ASD [21,47,48,[61][62][63][64][65]. The incidence of ASD in the present study, based on the above-mentioned criteria, was 40.7% (11 out of patients), confirming that dynamic stabilization seems not to prevent degeneration of the adjacent segment.…”

“…We compared the results of the postoperative evaluation with the preoperative imaging. We considered the progression of degeneration of the adjacent segment as defined by Han et al: (1) disc height reduction > 3 mm on lateral radiograph; (2) onset or progression of vertebral slippage > 3 mm at the adjacent segment compared with the preoperative condition seen on lateral radiograph; (3) onset or progression of osteophytes and endplate sclerosis compared with the preoperative condition [21].…”

Risk factors for upper adjacent segment degeneration after multi-level posterior lumbar spinal fusion surgery

“…Some researches have suggested that preoperative disc degeneration is related with radiographic ASD [9, 12]. Intrinsic disc degeneration causes the increase of disc stress at the adjacent segment [13, 14].…”

A comparison of long-term efficacy of K-rod-assisted non-fusion operation and posterior lumbar interbody fusion for single-segmental lumbar disc herniation

“…The K-rod system (which stands for K-rod system-assisted elastic internal xation) is another surgical modality for the management of degenerative diseases of the spine, such as disc herniation. The short-term clinical e cacy of the K-rod system in the treatment of lumbar degenerative diseases has been con rmed, [12][13][14] but there are few reports examining its long-term clinical e cacy. Furthermore, considering that ASD occurs approximately 2 years after lumbar surgery and the incidence of ASD increases at a rate of approximately 3% per year, 1,3 it is necessary to explore the long-term clinical e cacy of surgical treatment methods for degenerative diseases of the spine.…”