Unintended facet fusions after Dynesys dynamic stabilization in patients with spondylolisthesis

Abstract

<jats:sec><jats:title>OBJECTIVE</jats:title><jats:p>The pedicle screw–based Dynesys dynamic stabilization (DDS) has reportedly become a surgical option for lumbar spondylosis and spondylolisthesis. However, it is still unclear whether the dynamic construct remains mobile or eventually fuses. The aim of this study was to investigate the incidence of unintended facet arthrodesis after DDS and its association with spondylolisthesis.</jats:p></jats:sec><jats:sec><jats:title>METHODS</jats:title><jats:p>This retrospective study was designed to review 105 consecutive patients with 1- or 2-level lumbar spondylosis who were treated with DDS surgery. The patients were then divided into 2 groups according to preexisting spondylolisthesis or not. All patients underwent laminectomies, foraminotomies, and DDS. The clinical outcomes were measured using visual analog scale (VAS) scores for back and leg pain, Japanese Orthopaedic Association (JOA) scores, and Oswestry Disability Index (ODI) scores. All medical records, including pre- and postoperative radiographs, CT scans, and MR images, were also reviewed and compared.</jats:p></jats:sec><jats:sec><jats:title>RESULTS</jats:title><jats:p>A total of 96 patients who completed the postoperative follow-up for more than 30 months were analyzed. The mean age was 64.1 ± 12.9 years, and the mean follow-up duration was 46.3 ± 12.0 months. There were 45 patients in the spondylolisthesis group and 51 patients in the nonspondylolisthesis group. The overall prevalence rate of unintended facet fusion was 52.1% in the series of DDS. Patients with spondylolisthesis were older (67.8 vs 60.8 years, p = 0.007) and had a higher incidence rate of facet arthrodesis (75.6% vs 31.4%, p &lt; 0.001) than patients without spondylolisthesis. Patients who had spondylolisthesis or were older than 65 years were more likely to have facet arthrodesis (OR 6.76 and 4.82, respectively). There were no significant differences in clinical outcomes, including VAS back and leg pain, ODI, and JOA scores between the 2 groups. Furthermore, regardless of whether or not unintended facet arthrodesis occurred, all patients experienced significant improvement (all p &lt; 0.05) in the clinical evaluations.</jats:p></jats:sec><jats:sec><jats:title>CONCLUSIONS</jats:title><jats:p>During the mean follow-up of almost 4 years, the prevalence of unintended facet arthrodesis was 52.1% in patients who underwent DDS. Although the clinical outcomes were not affected, elderly patients with spondylolisthesis might have a greater chance of facet fusion. This could be a cause of the limited range of motion at the index levels long after DDS.</jats:p></jats:sec>

Unintentional Fusion in Preserved Facet Joints without Bone Grafting after Percutaneous Endoscopic Transforaminal Lumbar Interbody Fusion

“…Reports have described bone facet regrowth and unintended facet arthrodesis after lumbar decompression and lumbar dynamic stabilization surgery [16][17][18][19][20][21] . Dohzono et al 16) evaluated bone regrowth at facet joints 2 years after microendoscopic lumbar decompression surgery and reported a significant correlation between bone regrowth and percentage slippage in lumbar spondylolisthesis.…”

“…Kanayama et al 18,19) reported that facet fusion occurred in 12 of 64 patients (18.8%) and 14 of 43 patients (32.6%) by an average of 59.5 months and 82 months, respectively, after posterior lumbar dynamic stabilization surgery using the Graf artificial ligament. Fay et al 21) reported that unintended facet fusion occurred in 52.1% of patients 4 years after Dynesys dynamic stabilization. Furthermore, Fay et al 21) reported that facet fusion was significantly greater in patients with lumbar spondylolisthesis and those over the age of 65 years.…”

“…Fay et al 21) reported that unintended facet fusion occurred in 52.1% of patients 4 years after Dynesys dynamic stabilization. Furthermore, Fay et al 21) reported that facet fusion was significantly greater in patients with lumbar spondylolisthesis and those over the age of 65 years. These reports suggest that bone regrowth is likely to occur when spinal instability is present.…”

Effects of smoking on pedicle screw–based dynamic stabilization: radiological and clinical evaluations of screw loosening in 306 patients

“…The actual goal for preservation of segmental mobility and reduction of ASD in DDS remained equivocal. 14,15,17,18,32 Despite the fact that DDS is designed to stabilize the spine while allowing controlled motion, limited motion at the instrumented level of the lumbar spine has been reported, which can cause an overload of the adjacent segments and result in ASD. In the review study, 3.7% (0%-8.4%) of patients underwent secondary reoperation due to ASD, which was lower than fusion surgery (13%).…”

“…Pedicle screw-based dynamic stabilization has been reported as an effective and viable option in surgical management of lumbar spondylosis. [13][14][15][16][17][18] As opposed to fusion, the most commonly raised question regarding these screws, which do not aim to fuse the spine, is their risk of loosening. This risk in pedicle screw-based dynamic stabilization has reportedly been approximately 5% per screw and 20% per patient in 2-5 years postoperatively.…”