The Effect of Lumbar Lordosis on Screw Loosening in Dynesys Dynamic Stabilization: Four-Year Follow-Up with Computed Tomography

Introduction. This study aimed to evaluate the effects of Dynesys dynamic stabilization (DDS) on clinical and radiographic outcomes, including spinal pelvic alignment.Method. Consecutive patients who underwent 1- or 2-level DDS for lumbar spondylosis, mild degenerative spondylolisthesis, or degenerative disc disease were included. Clinical outcomes were evaluated by Visual Analogue Scale for back and leg pain, Oswestry Disability Index, and the Japanese Orthopedic Association scores. Radiographic outcomes were assessed by radiographs and computed tomography. Pelvic incidence and lumbar lordosis (LL) were also compared.Results. In 206 patients with an average follow-up of 51.1 ± 20.8 months, there were 87 screws (8.2%) in 42 patients (20.4%) that were loose. All clinical outcomes improved at each time point after operation. Patients with loosened screws were 45 years older. Furthermore, there was a higher risk of screw loosening in DDS involving S1, and these patients were more likely to have loosened screws if the LL failed to increase after the operation.Conclusions. The DDS screw loosening rate was overall 8.2% per screw and 20.4% per patient at more than 4 years of follow-up. Older patients, S1 involvement, and those patients who failed to gain LL postoperatively were at higher risk of screw loosening.

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Clinical outcomes of the Dynesys dynamic neutralization system: 1-year preliminary results

Neurosurgical FOCUS ◽

10.3171/foc.2007.22.1.8 ◽

2007 ◽

Vol 22 (1) ◽

pp. 1-8 ◽

Cited By ~ 75

Author(s):

William C. Welch ◽

Boyle C. Cheng ◽

Tariq E. Awad ◽

Reginald Davis ◽

James H. Maxwell ◽

...

Keyword(s):

Back Pain ◽

Clinical Outcomes ◽

Short Form ◽

Donor Site ◽

Degenerative Spondylolisthesis ◽

Dynamic Stabilization ◽

Leg Pain ◽

Pain Patient ◽

Tissue Destruction

Object In this study the authors present the preliminary clinical outcomes of dynamic stabilization with the Dynesys spinal system as part of a multicenter randomized prospective Food and Drug Administration (FDA) investigational device exemption (IDE) clinical trial. Methods This study included 101 patients from six IDE sites (no participants were omitted from the analysis) who underwent dynamic stabilization of the lumbar spine with the Dynesys construct. Patient participation was based on the presence of degenerative spondylolisthesis or retrolisthesis (Grade I), lateral or central spinal stenosis, and their physician's determination that the patient required decompression and instrumented fusion for one or two contiguous spinal levels between L-1 and S-1. Participants were evaluated preoperatively, postoperatively at 3 weeks, and then at 3-, 6-, and 12-month intervals. The 100-mm visual analog scale was used to score both lower-limb and back pain. Patient functioning was evaluated using the Oswestry Disability Index (ODI), and the participants' general health was assessed using the Short Form-12 questionnaire. Overall patient satisfaction was also reported. One hundred one patients (53 women and 48 men) with a mean age of 56.3 years (range 27–79 years) were included. The mean pain and function scores improved significantly from the baseline to 12-month follow-up evaluation, as follows: leg pain improved from 80.3 to 25.5, back pain from 54 to 29.4, and ODI score from 55.6 to 26.3%. Conclusions The early clinical outcomes of treatment with Dynesys are promising, with lessening of pain and disability found at follow-up review. Dynesys may be preferable to fusion for surgical treatment of degenerative spondylolisthesis and stenosis because it decreases back and leg pain while avoiding the relatively greater tissue destruction and the morbidity of donor site problems encountered in fusion. However, long-term follow-up care is still recommended.

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Comparative Effectiveness of Expandable Versus Static Interbody Spacers via MIS LLIF: A 2-Year Radiographic and Clinical Outcomes Study

Global Spine Journal ◽

10.1177/2192568219886278 ◽

2019 ◽

Vol 10 (8) ◽

pp. 998-1005

Author(s):

Yan Michael Li ◽

Richard F. Frisch ◽

Zheng Huang ◽

James Towner ◽

Yan Icy Li ◽

...

Keyword(s):

Clinical Outcomes ◽

Leg Pain ◽

Disc Disease ◽

Radiographic Outcomes ◽

Pain Scores ◽

Institutional Review ◽

Average Improvement ◽

Minimally Invasive Spine ◽

Static Group

Study Design: Retrospective cohort study. Objective: The purpose of this study is to compare the radiographic and clinical outcomes of expandable interbody spacers to static interbody spacers. Methods: This is a retrospective, institutional review board–exempt chart review of 62 consecutive patients diagnosed with degenerative disc disease who underwent minimally invasive spine surgery lateral lumbar interbody fusion (MIS LLIF) using static or expandable spacers. There were 27 patients treated with static spacers, and 35 with expandable spacers. Radiographic and clinical functional outcomes were collected. Statistical results were significant if P < .05. Results: Mean improvement in visual analogue scale back and leg pain scores was significantly greater in the expandable group compared to the static group at 6 and 24 months by 42.3% and 63.8%, respectively ( P < .05). Average improvement in Oswestry Disability Index scores was significantly greater in the expandable group than the static group at 3, 6, 12, and 24 months by 28%, 44%, 59%, 53%, and 89%, respectively ( P < .05). For disc height, the mean improvement from baseline to 24 months was greater in the static group compared to the expandable group ( P < .05). Implant subsidence was significantly greater in the static group (16.1%, 5/31 levels) compared with the expandable group (6.7%, 3/45 levels; P < .05). Conclusions: This study showed positive clinical and radiographic outcomes for patients who underwent MIS LLIF with expandable spacers compared to those with static spacers. Sagittal correction and pain relief was achieved and maintained through 24-month follow-up. The expandable group had a lower subsidence rate than the static group.

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Dynesys dynamic stabilization–related facet arthrodesis

Neurosurgical FOCUS ◽

10.3171/2015.10.focus15404 ◽

2016 ◽

Vol 40 (1) ◽

pp. E4 ◽

Cited By ~ 11

Author(s):

Li-Yu Fay ◽

Peng-Yuan Chang ◽

Jau-Ching Wu ◽

Wen-Cheng Huang ◽

Chun-Hao Wang ◽

...

Keyword(s):

Clinical Outcomes ◽

Japanese Orthopaedic Association ◽

Dynamic Stabilization ◽

Leg Pain ◽

Clinical Evaluations ◽

Radiological Data ◽

Spinal Segments ◽

Lumbar Spinal ◽

Limited Motion

OBJECTIVE Dynamic stabilization devices are designed to stabilize the spine while preserving some motion. However, there have been reports demonstrating limited motion at the instrumented level of the lumbar spine after Dynesys dynamic stabilization (DDS). The causes of this limited motion and its actual effects on outcomes after DDS remain elusive. In this study, the authors investigate the incidence of unintended facet arthrodesis after DDS and clinical outcomes. METHODS This retrospective study included 80 consecutive patients with 1- or 2-level lumbar spinal stenosis who underwent laminectomy and DDS. All medical records, radiological data, and clinical evaluations were analyzed. Imaging studies included pre- and postoperative radiographs, MR images, and CT scans. Clinical outcomes were measured by a visual analog scale (VAS) for back and leg pain, the Oswestry Disability Index (ODI), and Japanese Orthopaedic Association (JOA) scores. Furthermore, all patients had undergone postoperative CT for the detection of unintended arthrodesis of the facets at the indexed level, and range of motion was measured on standing dynamic radiographs. RESULTS A total of 70 patients (87.5%) with a mean age of 64.0 years completed the minimum 24-month postoperative follow-up (mean duration 29.9 months). Unintended facet arthrodesis at the DDS instrumented level was demonstrated by CT in 38 (54.3%) of the 70 patients. The mean age of patients who had facet arthrodesis was 9.8 years greater than that of the patients who did not (68.3 vs 58.5 years, p = 0.009). There were no significant differences in clinical outcomes, including VAS back and leg pain, ODI, and JOA scores between patients with and without the unintended facet arthrodesis. Furthermore, those patients older than 60 years were more likely to have unintended facet arthrodesis (OR 12.42) and immobile spinal segments (OR 2.96) after DDS. Regardless of whether unintended facet arthrodesis was present or not, clinical evaluations demonstrated improvement in all patients (all p < 0.05). CONCLUSIONS During the follow-up of more than 2 years, unintended facet arthrodesis was demonstrated in 54.3% of the patients who underwent 1- or 2-level DDS. Older patients (age > 60 years) were more likely to have unintended facet arthrodesis and subsequent immobile spinal segments. However, unintended facet arthrodesis did not affect the clinical outcomes during the study period. Further evaluations are needed to clarify the actual significance of this phenomenon.

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Radiographic and clinical outcomes following combined lateral lumbar interbody fusion and posterior segmental stabilization in patients with adult degenerative scoliosis

Neurosurgical FOCUS ◽

10.3171/2014.3.focus13368 ◽

2014 ◽

Vol 36 (5) ◽

pp. E11 ◽

Cited By ~ 39

Author(s):

Zachary J. Tempel ◽

Gurpreet S. Gandhoke ◽

Christopher M. Bonfield ◽

David O. Okonkwo ◽

Adam S. Kanter

Keyword(s):

Clinical Outcomes ◽

Lumbar Lordosis ◽

Hybrid Approach ◽

Vertical Axis ◽

Leg Pain ◽

Degenerative Scoliosis ◽

Sagittal Vertical Axis ◽

Adult Degenerative Scoliosis ◽

The Mean

Object A hybrid approach of minimally invasive lateral lumbar interbody fusion (LLIF) followed by supplementary open posterior segmental instrumented fusion (PSIF) has shown promising early results in the treatment of adult degenerative scoliosis. Studies assessing the impact of this combined approach on correction of segmental and regional coronal angulation, sagittal realignment, maximum Cobb angle, restoration of lumbar lordosis, and clinical outcomes are needed. The authors report their results of this approach for correction of adult degenerative scoliosis. Methods Twenty-six patients underwent combined LLIF and PSIF in a staged fashion. The patient population consisted of 21 women and 5 men. Ages ranged from 40 to 77 years old. Radiographic measurements including coronal angulation, pelvic incidence, lumbar lordosis, and sagittal vertical axis were taken preoperatively and 1 year postoperatively in all patients. Concurrently, the visual analog score (VAS) for back and leg pain, the Oswestry Disability Index (ODI), and Short Form-36 (SF-36) Physical Component Summary (PCS) and Mental Component Summary (MCS) scores were used to assess clinical outcomes in 19 patients. Results At 1-year follow-up, all patients who underwent combined LLIF and PSIF achieved statistically significant mean improvement in regional coronal angles (from 14.9° to 5.8°, p < 0.01) and segmental coronal angulation at all operative levels (p < 0.01). The maximum Cobb angle was significantly reduced postoperatively (from 41.1° to 15.1°, p < 0.05) and was maintained at follow-up (12.0°, p < 0.05). The mean lumbar lordosis–pelvic incidence mismatch was significantly improved postoperatively (from 15.0° to 6.92°, p < 0.05). Although regional lumbar lordosis improved (from 43.0° to 48.8°), it failed to reach statistical significance (p = 0.06). The mean sagittal vertical axis was significantly improved postoperatively (from 59.5 mm to 34.2 mm, p < 0.01). The following scores improved significantly after surgery: VAS for back pain (from 7.5 to 4.3, p < 0.01) and leg pain (from 5.8 to 3.1, p < 0.01), ODI (from 48 to 38, p < 0.01), and PCS (from 27.5 to 35.0, p = 0.01); the MCS score did not improve significantly (from 43.2 to 45.5, p = 0.37). There were 3 major and 10 minor complications. Conclusions A hybrid approach of minimally invasive LLIF and open PSIF is an effective means of achieving correction of both coronal and sagittal deformity, resulting in improvement of quality of life in patients with adult degenerative scoliosis.

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

Journal of Neurosurgery Spine ◽

10.3171/2020.2.spine191380 ◽

2020 ◽

Vol 33 (3) ◽

pp. 398-405

Author(s):

Yi-Hsuan Kuo ◽

Chao-Hung Kuo ◽

Hsuan-Kan Chang ◽

Tsung-Hsi Tu ◽

Li-Yu Fay ◽

...

Keyword(s):

Lumbar Spine ◽

Pedicle Screw ◽

Clinical Outcomes ◽

Dynamic Stabilization ◽

Leg Pain ◽

Lumbar Spine Surgery ◽

Screw Loosening ◽

Secondary Surgery ◽

Clinical Evaluations ◽

Vas Scores

OBJECTIVECigarette smoking has been known to increase the risk of pseudarthrosis in spinal fusion. However, there is a paucity of data on the effects of smoking in dynamic stabilization following lumbar spine surgery. This study aimed to investigate the clinical outcomes and the incidence of screw loosening among patients who smoked.METHODSConsecutive patients who had lumbar spondylosis, recurrent disc herniations, or low-grade spondylolisthesis that was treated with 1- or 2-level surgical decompression and pedicle screw–based Dynesys dynamic stabilization (DDS) were retrospectively reviewed. Patients who did not complete the minimum 2 years of radiological and clinical evaluations were excluded. All screw loosening was determined by both radiographs and CT scans. Patient-reported outcomes, including visual analog scale (VAS) scores of back and leg pain, Japanese Orthopaedic Association (JOA) scores, and Oswestry Disability Index (ODI), were analyzed. Patients were grouped by smoking versus nonsmoking, and loosening versus intact screws, respectively. All radiological and clinical outcomes were compared between the groups.RESULTSA total of 306 patients (140 women), with a mean age of 60.2 ± 12.5 years, were analyzed during an average follow-up of 44 months. There were 34 smokers (9 women) and 272 nonsmokers (131 women, 48.2% more than the 26.5% of smokers, p = 0.017). Postoperatively, all the clinical outcomes improved (e.g., VAS back and leg pain, JOA scores, and ODI, all p < 0.001). The overall rate of screw loosening was 23.2% (71 patients), and patients who had loosened screws were older (61.7 ± 9.6 years vs 59.8 ± 13.2 years, p = 0.003) and had higher rates of diabetes mellitus (33.8% vs 21.7%, p = 0.038) than those who had intact DDS screws. Although the patients who smoked had similar clinical improvement (even better VAS scores in their legs, p = 0.038) and a nonsignificantly lower rate of screw loosening (17.7% and 23.9%, p = 0.416), the chances of secondary surgery for adjacent segment disease (ASD) were higher than for the nonsmokers (11.8% vs 1.5%, p < 0.001).CONCLUSIONSSmoking had no adverse effects on the improvements of clinical outcomes in the pedicle screw–based DDS surgery. For smokers, the rate of screw loosening trended lower (without significance), but the chances of secondary surgery for ASD were higher than for the nonsmoking patients. However, the optimal surgical strategy to stabilize the lumbar spine of smoking patients requires future investigation.

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

Journal of Neurosurgery Spine ◽

10.3171/2018.1.spine17993 ◽

2018 ◽

Vol 29 (3) ◽

pp. 250-258 ◽

Cited By ~ 7

Author(s):

Chao-Hung Kuo ◽

Wen-Cheng Huang ◽

Jau-Ching Wu ◽

Tsung-Hsi Tu ◽

Li-Yu Fay ◽

...

Keyword(s):

Clinical Outcomes ◽

Disc Degeneration ◽

Interbody Fusion ◽

Degenerative Spondylolisthesis ◽

Transforaminal Lumbar Interbody Fusion ◽

Adjacent Segment Degeneration ◽

Dynamic Stabilization ◽

Adjacent Segment ◽

Secondary Surgery

OBJECTIVEPedicle 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).METHODSThe 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.RESULTSA 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).CONCLUSIONSThe 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.

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Dynamic stabilization for L4–5 spondylolisthesis: comparison with minimally invasive transforaminal lumbar interbody fusion with more than 2 years of follow-up

Neurosurgical FOCUS ◽

10.3171/2015.10.focus15441 ◽

2016 ◽

Vol 40 (1) ◽

pp. E3 ◽

Cited By ~ 13

Author(s):

Chao-Hung Kuo ◽

Peng-Yuan Chang ◽

Jau-Ching Wu ◽

Hsuan-Kan Chang ◽

Li-Yu Fay ◽

...

Keyword(s):

Clinical Outcomes ◽

Interbody Fusion ◽

Japanese Orthopaedic Association ◽

Transforaminal Lumbar Interbody Fusion ◽

Dynamic Stabilization ◽

Leg Pain ◽

Lumbar Interbody Fusion ◽

Analog Scale ◽

Time Point

OBJECTIVE In the past decade, dynamic stabilization has been an emerging option of surgical treatment for lumbar spondylosis. However, the application of this dynamic construct for mild spondylolisthesis and its clinical outcomes remain uncertain. This study aimed to compare the outcomes of Dynesys dynamic stabilization (DDS) with minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) for the management of single-level spondylolisthesis at L4–5. METHODS This study retrospectively reviewed 91 consecutive patients with Meyerding Grade I spondylolisthesis at L4–5 who were managed with surgery. Patients were divided into 2 groups: DDS and MI-TLIF. The DDS group was composed of patients who underwent standard laminectomy and the DDS system. The MI-TLIF group was composed of patients who underwent MI-TLIF. Clinical outcomes were evaluated by visual analog scale for back and leg pain, Oswestry Disability Index, and Japanese Orthopaedic Association scores at each time point of evaluation. Evaluations included radiographs and CT scans for every patient for 2 years after surgery. RESULTS A total of 86 patients with L4–5 spondylolisthesis completed the follow-up of more than 2 years and were included in the analysis (follow-up rate of 94.5%). There were 64 patients in the DDS group and 22 patients in the MI-TLIF group, and the overall mean follow-up was 32.7 months. Between the 2 groups, there were no differences in demographic data (e.g., age, sex, and body mass index) or preoperative clinical evaluations (e.g., visual analog scale back and leg pain, Oswestry Disability Index, and Japanese Orthopaedic Association scores). The mean estimated blood loss of the MI-TLIF group was lower, whereas the operation time was longer compared with the DDS group (both p < 0.001). For both groups, clinical outcomes were significantly improved at 6, 12, 18, and 24 months after surgery compared with preoperative clinical status. Moreover, there were no differences between the 2 groups in clinical outcomes at each evaluation time point. Radiological evaluations were also similar and the complication rates were equally low in both groups. CONCLUSIONS At 32.7 months postoperation, the clinical and radiological outcomes of DDS were similar to those of MI-TLIF for Grade I degenerative spondylolisthesis at L4–5. DDS might be an alternative to standard arthrodesis in mild lumbar spondylolisthesis. However, unlike fusion, dynamic implants have issues of wearing and loosening in the long term. Thus, the comparable results between the 2 groups in this study require longer follow-up to corroborate.

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Clinical Outcomes of Trans-Sacral Epiduroscopic Laser Decompression (SELD) in Patients with Lumbar Disc Herniation

Pain Research and Management ◽

10.1155/2020/1537875 ◽

2020 ◽

Vol 2020 ◽

pp. 1-8

Author(s):

Seong Son ◽

Sang Gu Lee ◽

Yong Ahn ◽

Woo Kyung Kim

Keyword(s):

Clinical Outcomes ◽

Lumbar Disc Herniation ◽

Disc Herniation ◽

Lumbar Disc ◽

Leg Pain ◽

Herniated Disc ◽

Low Back ◽

Invasive Treatment ◽

Disc Disease

Objective. Nowadays, trans-sacral epiduroscopic laser decompression (SELD) using slender epiduroscopy and laser is one of the preferred options for minimally invasive treatment in lumbar disc diseases. However, SELD is still in the initial stages of the global field of spine surgery, and the clinical outcomes in patients with lumbar disc herniation are not established yet. Therefore, the authors investigated patients undergoing SELD to report the clinical results. Methods. Between November 2015 and November 2018, a total of 82 patients who underwent single-level SELD for lumbar disc herniation with a minimum follow-up of 6.0 months were enrolled. A retrospective review of clinical data was conducted. Clinical outcomes were evaluated using the visual analogue scale (VAS) for low back and leg pain and Odom’s criteria. Also, surgical outcomes, including complications and symptom recurrences, and radiological outcomes were analyzed. Results. Low back pain and leg pain as determined by the VAS improved from an average of 5.43 ± 1.73 and 6.10 ± 1.67 to 2.80 ± 1.43 and 3.58 ± 2.08 at the final follow-up (p<0.001). According to Odom’s criteria, the success rate defined as excellent or good results at the final follow-up was 58.5%. There were no surgery-related complications such as neurologic deficits, infection, or epidural hematomas, except for transient mild paralysis in 3 patients and procedure-related nuchal pain in 2 patients. The rate of additional procedures was 17.0% (6 patients received revision surgery and 8 patients received an additional nerve block) during the follow-up. Conclusion. Our findings showed that SELD for lumbar herniated disc disease achieved less favorable clinical outcomes compared with those of previous studies. Further study is needed to clarify the influencing factors on the clinical outcomes of SELD.

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Unintended facet fusions after Dynesys dynamic stabilization in patients with spondylolisthesis

Journal of Neurosurgery Spine ◽

10.3171/2018.8.spine171328 ◽

2019 ◽

Vol 30 (3) ◽

pp. 353-361 ◽

Cited By ~ 1

Author(s):

Li-Yu Fay ◽

Wen-Cheng Huang ◽

Chih-Chang Chang ◽

Hsuan-Kan Chang ◽

Tzu-Yun Tsai ◽

...

Keyword(s):

Clinical Outcomes ◽

Japanese Orthopaedic Association ◽

Limited Range ◽

Dynamic Stabilization ◽

Leg Pain ◽

Lumbar Spondylosis ◽

Limited Range Of Motion ◽

Vas Scores ◽

The Mean

OBJECTIVEThe 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.METHODSThis 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.RESULTSA 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 < 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 < 0.05) in the clinical evaluations.CONCLUSIONSDuring 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.

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Pedicle screw loosening in dynamic stabilization: incidence, risk, and outcome in 126 patients

Neurosurgical FOCUS ◽

10.3171/2011.7.focus11125 ◽

2011 ◽

Vol 31 (4) ◽

pp. E9 ◽

Cited By ~ 61

Author(s):

Jau-Ching Wu ◽

Wen-Cheng Huang ◽

Hsiao-Wen Tsai ◽

Chin-Chu Ko ◽

Ching-Lan Wu ◽

...

Keyword(s):

Clinical Outcomes ◽

Serum Glucose ◽

Dynamic Stabilization ◽

Diabetic Patients ◽

Screw Loosening ◽

Osseous Integration ◽

Incidence Risk ◽

The Mean ◽

Lumbar Dynamic Stabilization

Object The long-term outcome of lumbar dynamic stabilization is uncertain. This study aimed to investigate the incidence, risk factors, and outcomes associated with screw loosening in a dynamic stabilization system. Methods The authors conducted a retrospective review of medical records, radiological studies, and clinical evaluations obtained in consecutive patients who underwent 1- or 2-level lumbar dynamic stabilization and were followed up for more than 24 months. Loosening of screws was determined on radiography and CT scanning. Radiographic and standardized clinical outcomes, including the visual analog scale (VAS) and Oswestry Disability Index (ODI) scores, were analyzed with a focus on cases in which screw loosening occurred. Results The authors analyzed 658 screws in 126 patients, including 54 women (42.9%) and 72 men (57.1%) (mean age 60.4 ± 11.8 years). During the mean clinical follow-up period of 37.0 ± 7.1 months, 31 screws (4.7%) in 25 patients (19.8%) were shown to have loosened. The mean age of patients with screw loosening was significantly higher than those without loosening (64.8 ± 8.8 vs 59.3 ± 12.2, respectively; p = 0.036). Patients with diabetes mellitus had a significantly higher rate of screw loosening compared with those without diabetes (36.0% vs 15.8%, respectively; p = 0.024). Diabetic patients with well-controlled serum glucose (HbA1c ≤ 8.0%) had a significantly lower chance of screw loosening than those without well-controlled serum glucose (28.6% vs 71.4%, respectively; p = 0.021). Of the 25 patients with screw loosening, 22 cases (88%) were identified within 6.6 months of surgery; 18 patients (72%) had the loosened screws in the inferior portion of the spinal construct, whereas 7 (28%) had screw loosening in the superior portion of the construct. The overall clinical outcomes at 3, 12, and 24 months, measured by VAS for back pain, VAS for leg pain, and ODI scores, were significantly improved after surgery compared with before surgery (all p < 0.05). There were no significant differences between the patients with and without screw loosening at all evaluation time points (all p > 0.05). All 25 patients with screw loosening were asymptomatic, and in 6 (24%) osseous integration was demonstrated on later follow-up. Also, there were 3 broken screws (2.38% in 126 patients or 0.46% in 658 screws). To date, none of these loosened or broken screws have required revision surgery. Conclusions Screw loosening in dynamic stabilization systems is not uncommon (4.7% screws in 19.8% patients). Patients of older age or those with diabetes have higher rates of screw loosening. Screw loosening can be asymptomatic and presents opportunity for osseous integration on later follow-up. Although adverse effects on clinical outcomes are rare, longer-term follow-up is required in cases in which screws become loose.

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