Radiological adjacent-segment degeneration in L4–5 spondylolisthesis: comparison between dynamic stabilization and minimally invasive transforaminal lumbar interbody fusion

Abstract

<jats:sec><jats:title>OBJECTIVE</jats:title><jats:p>Pedicle screw–based dynamic stabilization has been an alternative to conventional lumbar fusion for the surgical management of low-grade spondylolisthesis. However, the true effect of dynamic stabilization on adjacent-segment degeneration (ASD) remains undetermined. Authors of this study aimed to investigate the incidence of ASD and to compare the clinical outcomes of dynamic stabilization and minimally invasive transforaminal lumbar interbody fusion (MI-TLIF).</jats:p></jats:sec><jats:sec><jats:title>METHODS</jats:title><jats:p>The records of consecutive patients with Meyerding grade I degenerative spondylolisthesis who had undergone surgical management at L4–5 in the period from 2007 to 2014 were retrospectively reviewed. Patients were divided into two groups according to the surgery performed: Dynesys dynamic stabilization (DDS) group and MI-TLIF group. Pre- and postoperative radiological evaluations, including radiography, CT, and MRI studies, were compared. Adjacent discs were evaluated using 4 radiological parameters: instability (antero- or retrolisthesis), disc degeneration (Pfirrmann classification), endplate degeneration (Modic classification), and range of motion (ROM). Clinical outcomes, measured with the visual analog scale (VAS) for back and leg pain, the Oswestry Disability Index (ODI), and the Japanese Orthopaedic Association (JOA) scores, were also compared.</jats:p></jats:sec><jats:sec><jats:title>RESULTS</jats:title><jats:p>A total of 79 patients with L4–5 degenerative spondylolisthesis were included in the analysis. During a mean follow-up of 35.2 months (range 24–89 months), there were 56 patients in the DDS group and 23 in the MI-TLIF group. Prior to surgery, both groups were very similar in demographic, radiological, and clinical data. Postoperation, both groups had similarly significant improvement in clinical outcomes (VAS, ODI, and JOA scores) at each time point of evaluation. There was a lower chance of disc degeneration (Pfirrmann classification) of the adjacent discs in the DDS group than in the MI-TLIF group (17% vs 37%, p = 0.01). However, the DDS and MI-TLIF groups had similar rates of instability (15.2% vs 17.4%, respectively, p = 0.92) and endplate degeneration (1.8% vs 6.5%, p = 0.30) at the cranial (L3–4) and caudal (L5–S1) adjacent levels after surgery. The mean ROM in the cranial and caudal levels was also similar in the two groups. None of the patients required secondary surgery for any ASD (defined by radiological criteria).</jats:p></jats:sec><jats:sec><jats:title>CONCLUSIONS</jats:title><jats:p>The clinical improvements after DDS were similar to those following MI-TLIF for L4–5 Meyerding grade I degenerative spondylolisthesis at 3 years postoperation. According to radiological evaluations, there was a lower chance of disc degeneration in the adjacent levels of the patients who had undergone DDS. However, other radiological signs of ASD, including instability, endplate degeneration, and ROM, were similar between the two groups. Although none of the patients in the present series required secondary surgery, a longer follow-up and a larger number of patients would be necessary to corroborate the protective effect of DDS against ASD.</jats:p></jats:sec>

Upright MRI after decompression of spinal stenosis and concurrent spondylolisthesis

“…Furthermore we did not see any adjacent-segment degeneration, which is frequently seen even after motion-preserving instrumented procedures. 17 The analysis to find any preoperative predictors of instability did not show that disc height could be predictive. Although our findings are extremely limited by the size of our group, they corroborate the findings of Schär et al 25 The limitations of our study are obvious (small number, retrospective nature, selection bias related to patients' ability to get to the study facility).…”

Unintended facet fusions after Dynesys dynamic stabilization in patients with spondylolisthesis

“…We conducted studies to compare lumbar fusion with dynamic stabilization with an average follow-up of more than 2 years. 14,15 Kuo et al first examined 86 patients with L4-5 spondylolisthesis and demonstrated that the clinical and radiological outcomes of DDS were similar to those of minimally invasive transforaminal lumbar interbody fusion (mi-TLIF) for grade I spondylolisthesis after approximately 2.5 years postoperatively. Although DDS might be an alternative to standard arthrodesis in mild lumbar spondylolisthesis, the dynamic pedicle screws could have other issues like wearing and loosening in long-term follow-up.…”

“…Although none of the patients in the series required secondary surgery, a longer follow-up and a larger number of patients would be necessary to corroborate the protective effect of DDS against ASD. 15 The current study aimed specifically to investigate the differences among patients with and without spondylolisthesis after dynamic stabilization and thus did not include patients who underwent lumbar fusions. It remains elusive how spondylolisthesis might affect the theoretical benefit of DDS in the amelioration of ASD.…”

A Hybrid Dynamic Stabilization and Fusion System in Multilevel Lumbar Spondylosis

“…Regarding the issue of adjacent-segment degeneration (ASD), our group previously published a study to address ASD and found that the dynamic stabilization would lead to a lower chance of adjacent disc degeneration in comparison with interbody fusion [ 27 ]. The paper concluded that the clinical improvements after Dynesys were similar to those following fusion for L4–5 Meyerding grade I degenerative spondylolisthesis at 3-year postoperation.…”