Factors affecting clinical outcomes in treating patients with grade 1 degenerative spondylolisthesis using interspinous soft stabilization with a tension band system: a minimum 5-year follow-up

Functional outcome of surgical management of low mid-grade lumbar spondylolisthesis when considering the sagittal balance parameters preoperatively: a prospective study

BACKGROUND

Prospective study objectives. A sagittal balance is a good tool to improve the functional outcome of spine spondylolisthesis surgeries, primarily noted that it has a good impact in deformity surgery and then applied to every spine surgery and the aim of this study is to evaluate its functional outcome when considered in preoperative planning for non-dysplastic low- and mid-grade spondylolisthesis surgeries.

METHOD

Forty patients diagnosed as low- or mid-grade non-dysplastic spondylolisthesis had undergone surgery at Cairo University after failed medical treatment had been evaluated preoperatively by measuring the sagittal balance parameters which include SVA, spinopelvic angles, lumbar lordosis, pelvic tilt, sacral slope, and pelvic incidence and then measure it along a follow-up period of 1 year postoperatively started from February 2018 and correlate it with functional outcome using Oswestry score (ODI)and VAS. Correction of parameters has been estimated preoperatively by manual estimation and Surgimap application then applied during the operation.

RESULTS

All patients were treated by surgical treatment through posterior transpedicular screw fixation with conventional or reduction screws and fusion ± TLIF cages. The mean of lumbar lordosis and mean spinopelvic angles were increased in a statistically significant manner. Pelvis tilt was decreased in a statistically insignificant manner. The mean of pelvic incidence was not changed and statistically insignificant, and this is matching the fact that pelvic incidence is a constant parameter. The sacral slope was increased in a statistically insignificant manner. Final results showed that 37 had a statistically significant improvement in their ODI >20% at the last visit. Three patients had a poor clinical outcome with ODI scorFinal results showed that 37 had a statistically significant improvement in their ODI >20% at the last visit. Three patients had a poor clinical outcome with ODI score of >20% improvement, and we noticed that the level of pathology was at the level of L4L5, SVA was positive and worsen postoperatively, and also, it is accompanied by decreased lumbar lordosis. Change in ODI means statistically significant improvement when considering sagittal parameters preoperation and during operation.

CONCLUSION

Sagittal balance parameters should be considered in the surgical management of low-grade spondylolisthesis cases to improve their functional outcome.

Lumbar degenerative spondylolisthesis epidemiology: A systematic review with a focus on gender-specific and age-specific prevalence

The epidemiology of lumbar degenerative spondylolisthesis (DS) remains controversial. We performed a systematic review with the aim of gaining a better understanding of the prevalence of DS in the general population. The results showed that the prevalence of DS is very gender- and age-specific. Few women and men develop DS before they are 50 years old. After 50 years of age, both women and men begin to develop DS, with women having a faster rate of development than men. For elderly Chinese (≥ 65 years, mean age: 72.5 years), large population-based studies MsOS (Hong Kong, females: n = 2000) and MrOS (Hong Kong, males: n = 2000) showed DS prevalence was 25.0% in women and 19.1% in men. The female:male (F:M) prevalence ratio was 1.3:1. The published data for MsOS (USA) and MrOS (USA) studies seem to show that elderly Caucasian Americans have a higher DS prevalence, being approximately 60-70% higher than elderly Chinese; however, the F:M prevalence ratio was similar to the elderly Chinese population. Patient data showed that female patients more often received surgical treatment than male and preliminary data showed the ratio of female to male patients receiving surgical treatment did not differ between Northeast Asians (Chinese, Japanese, and Korean), Europeans, and American Caucasians, being around 2:1 in the elderly population. The existing data also suggest that menopause may be a contributing factor for the accelerated development of DS in postmenopausal women. The translational potential of this article: A better understanding of epidemiology of lumbar degenerative spondylolisthesis can support patient consultation and treatment planning.

The Correlation Between Restoration of Lumbar Lordosis and Surgical Outcome in the Treatment of Low-grade Lumbar Degenerative Spondylolisthesis With Spinal Fusion

STUDY DESIGN

Retrospective clinical study.

OBJECTIVE

To investigate the relationship between the restoration of the lumbar lordosis (LL) and the surgical outcome of patients undergoing spinal fusion for low-grade lumbar degenerative spondylolisthesis.

SUMMARY OF BACKGROUND DATA

Correlation between low back pain and the loss of LL in the treatment of low-grade lumbar degenerative spondylolisthesis has seldom been reported.

METHODS

Between May 2005 and July 2011, 59 patients with low back pain and neurogenic claudication due to low-grade lumbar degenerative spondylolisthesis underwent spinal decompression and fusion by a senior surgeon. Ten patients were lost to follow-up. The mean age of the remaining 49 patients (10 men and 39 women) was 64.0 years (range, 47-88 y). Patients were categorized on the basis of the spino-pelvic posture: type 1 [pelvic incidence (PI)<45 degrees] (n=12), type 2 (45 degrees≤PI≤60 degrees) (n=24), and type 3 (PI>60 degrees) (n=13). The LL restoration ratio was calculated by the actual LL divided by the predicted LL. The clinical results were evaluated using a visual analogue scale and the Oswestry Disability Index. Postoperative 36-inch spinal films were used to assess the sagittal balance.

RESULTS

The mean follow-up period was 43.2 months (range, 28-62 mo). Forty-eight patients showed significant improvement with respect to visual analogue scale and Oswestry Disability Index regardless of whether the LL was restored higher or lower. Postoperative 36-inch spinal films showed the C7 plumb line to be within an average of 4.4 cm (range, 0.6-5.6 cm) from the posterior-superior corner of the S1 vertebrae.

CONCLUSIONS

Patients with smaller PI tended to be restored higher, and those patients with a larger PI were more likely to be restored lower. For patients with normal sagittal balance, the surgical outcomes in the treatment of low-grade lumbar degenerative spondylolisthesis with spinal fusion are not correlated with restoration of the LL.

Sacral spinous processes: a morphologic classification and biomechanical characterization of strength

BACKGROUND

There has been increasing interest in using the lumbosacral spinous processes for fixation as a less invasive alternative to transpedicular instrumentation. Alhough prior studies have described the appearance and biomechanics of lumbar spinous processes, few have evaluated the dimensions, morphology, or strength of the sacral spinous processes.

PURPOSE

The goals of this study were to characterize the morphology of the S1 spinous process and biomechanical strength of the S1 spinous process when loaded in a cranial direction.

STUDY DESIGN

This study was performed as both an analysis of radiographic data and biomechanical testing of cadaveric specimens.

METHODS

Lumbosacral spine radiographs and computed tomography scans of 20 patients were evaluated for visibility and morphology of the S1 spinous process. S1 spinous process length, height, and size of the L5-S1 segment were measured. Additionally, 13 cadaveric lumbosacral spinal segments were obtained for biomechanical testing and morphologic analysis. Specimens were loaded at the S1 spinous process in a cranial direction via a strap, simulating resistance to a flexion moment applied across the L5-S1 segment. Peak load to failure, displacement, and mode of failure were recorded.

RESULTS

The S1 spinous process was clearly visible on lateral radiographs in only 10% of patients. Mean spinous process length (anterior-posterior) was 11.6 mm while mean spinous process height (cranial-caudal) was 23.1 mm. We identified six different morphologic subtypes of the S1 spinous process: fin, lumbar type, fenestrated, fused, tubercle, and spina bifida occulta. During tension loading of the S1 spinous process in the cephalad direction, mean peak load to failure was 439N, with 92% of specimens failing by fracture through the spinous process.

CONCLUSIONS

This is the first study evaluating sacral spinous process morphology, visibility, and biomechanical strength for potential instrumentation. Compared with lumbar spinous processes, sacral spinous processes are smaller with more variable morphology but have similar peak load to failure. For ideal visualization of morphology and suitability for interspinous fixation,preoperative three-dimensional imaging may be a valuable tool over plain radiographs.

Clinical and radiographic degenerative spondylolisthesis (CARDS) classification

BACKGROUND CONTEXT

Lumbar degenerative spondylolisthesis (DS) is a common, acquired condition leading to disabling back and/or leg pain. Although surgery is common used to treat patients with severe symptoms, there are no universally accepted treatment guidelines. Wide variation in vertebral translation, disc collapse, sagittal alignment, and vertebral mobility suggests this is a heterogeneous disease. A classification scheme would be useful to differentiate homogenous subgroups that may benefit from different treatment strategies.

PURPOSE

To develop and test the reliability of a simple, clinically useful classification scheme for lumbar DS.

STUDY DESIGN

Retrospective case series.

PATIENT SAMPLE

One hundred twenty-six patients.

OUTCOME MEASURES

Proposed radiographic classification system.

METHODS

A classification system is proposed that considers disc space height, sagittal alignment and translation, and the absence or presence of unilateral or bilateral leg pain. Test cases were graded by six observers to establish interobserver reliability and regraded in a different order 1 month later to establish intraobserver reliability using Kappa analysis. To establish the relative prevalence of each subtype, a series of 100 consecutive patients presenting with L4-L5 DS were classified.

RESULTS

Four radiographic subtypes were identified: Type A: advanced Disc space collapse without kyphosis; Type B: disc partially preserved with translation of 5 mm or less; Type C: disc partially preserved with translation of more than 5 mm; and Type D: kyphotic alignment. The leg pain modifier 0 denotes no leg pain, 1 denotes unilateral leg pain, and 2 represents bilateral leg pain. The Kappa value describing interobserver reliability was 0.82, representing near-perfect agreement. Intraobserver reliability analysis demonstrated Kappa=0.83, representing near-perfect agreement. Grading of the consecutive series of 100 patients revealed the following distribution: 16% Type A, 37% Type B, 33% Type C, and 14% Type D.

CONCLUSIONS

A new radiographic and clinical classification scheme for lumbar DS with high inter- and intraobserver reliabilites is proposed. Use of this classification scheme should facilitate communication to enhance the quality of outcomes research on DS.

Clinical significance of achieving a flexion limitation with a tension band system in grade 1 degenerative spondylolisthesis: a minimum 5-year follow-up

STUDY DESIGN

Retrospective clinical study.

OBJECTIVE

To evaluate the effect of the limitation of flexion rotation clinically and radiologically after interspinous soft stabilization using a tension band system in grade 1 degenerative spondylolisthesis.

SUMMARY OF BACKGROUND DATA

Although several studies have been published on the clinical effects of limiting rotatory motion using tension band systems, which mainly targets the limitation of flexion rather than that of extension, they were confined to the category of pedicle screw-based systems, revealing inconsistent long-term outcomes.

METHODS

Sixty-one patients with a mean age of 60.6 years (range, 28-76 yr) who underwent interspinous soft stabilization after decompression for grade 1 degenerative spondylolisthesis with stenosis between 2002 and 2004 were analyzed. At follow-up, the patients were divided into 2 groups on the basis of their achievement or failure to achieve flexion limitation. The clinical and radiological findings were analyzed. A multiple linear regression analysis was performed to determine the prognostic factors for surgical outcomes.

RESULTS

At a mean follow-up duration of 72.5 months (range, 61-82 mo), 51 patients were classified into the flexion-limited group and 10 into the flexion-unlimited group. Statistically significant improvements were noted only in the flexion-limited group in all clinical scores. In the flexion-unlimited group, there were significant deteriorations in flexion angle (P = 0.009), axial thickness of the ligamentum flavum (P = 0.013), and the foraminal cross-sectional area (P = 0.011), resulting in significant intergroup differences. The preoperative extension angle was identified as the most influential variable for the flexion limitation and the clinical outcomes.

CONCLUSION

The effects of the limitation of flexion rotation achieved through interspinous soft stabilization using a tension band system after decompression were related to the prevention of late recurrent stenosis and resultant radicular pain caused by flexion instability. The extension potential at the index level was recognized as a major prognostic factor that can predict the flexion limitation and the clinical results.

LEVEL OF EVIDENCE

4.

Decompression and paraspinous tension band: a novel treatment method for patients with lumbar spinal stenosis and degenerative spondylolisthesis

BACKGROUND CONTEXT

Prior studies have demonstrated the superiority of decompression and fusion over decompression alone for the treatment of lumbar degenerative spondylolisthesis with spinal stenosis. More recent studies have investigated whether nonfusion stabilization could provide durable clinical improvement after decompression and fusion.

PURPOSE

To examine the clinical safety and effectiveness of decompression and implantation of a novel flexion restricting paraspinous tension band (PTB) for patients with degenerative spondylolisthesis.

STUDY DESIGN

A prospective clinical study.

PATIENT SAMPLE

Forty-one patients (7 men and 34 women) aged 45 to 83 years (68.2 ± 9.0) were recruited with symptomatic spinal stenosis and Meyerding Grade 1 or 2 degenerative spondylolisthesis at L3-L4 (8) or L4-L5 (33).

OUTCOME MEASURES

Self-reported measures included visual analog scale (VAS) for leg, back, and hip pain and the Oswestry Disability Index (ODI). Physiologic measures included quantitative and qualitative radiographic analysis performed by an independent core laboratory.

METHODS

Patients with lumbar degenerative spondylolisthesis and stenosis were prospectively enrolled at four European spine centers with independent monitoring of data. Clinical and radiographic outcome data collected preoperatively were compared with data collected at 3, 6, 12, and 24 months after surgery. This study was sponsored by the PTB manufacturer (Simpirica Spine, Inc., San Carlos, CA, USA), including institutional research support grants to the participating centers totaling approximately US $172,000.

RESULTS

Statistically significant improvements and clinically important effect sizes were seen for all pain and disability measurements. At 24 months follow-up, ODI scores were reduced by an average of 25.4 points (59%) and maximum leg pain on VAS by 48.1 mm (65%). Back pain VAS scores improved from 54.1 by an average of 28.5 points (53%). There was one postoperative wound infection (2.4%) and an overall reoperation rate of 12%. Eighty-two percent patients available for 24 months follow-up with a PTB in situ had a reduction in ODI of greater than 15 points and 74% had a reduction in maximum leg pain VAS of greater than 20 mm. According to Odom criteria, most of these patients (82%) had an excellent or good outcome with all except one patient satisfied with surgery. As measured by the independent core laboratory, there was no significant increase in spondylolisthesis, segmental flexion-extension range of motion, or translation and no loss of lordosis in the patients with PTB at the 2 years follow-up.

CONCLUSIONS

Patients with degenerative spondylolisthesis and spinal stenosis treated with decompression and PTB demonstrated no progressive instability at 2 years follow-up. Excellent/good outcomes and significant improvements in patient-reported pain and disability scores were still observed at 2 years, with no evidence of implant failure or migration. Further study of this treatment method is warranted to validate these findings.

Characterization of the behavior of a novel low-stiffness posterior spinal implant under anterior shear loading on a degenerative spinal model

PURPOSE

Dynamic implants have been developed to address potential adjacent level effects due to rigid instrumentation. Rates of revision surgeries may be reduced by using improved implants in the primary surgery. Prior to clinical use, implants should be rigorously tested ex vivo. The objective of our study was to characterize the load-sharing and kinematic behavior of a novel low-stiffness spinal implant.

METHODS

A human cadaveric model of degenerative spondylolisthesis was tested in shear. Lumbar functional spinal units (N = 15) were tested under a static 300 N axial compression force and a cyclic anterior shear force (5-250 N). Translation was tracked with a motion capture system. A novel implant was compared to three standard implants with shear stiffness ranging from low to high. All implants were instrumented with strain gauges to measure the supported shear force. Each implant was affixed to each specimen, and the specimens were tested intact and in two progressively destabilized states.

RESULTS

Specimen condition and implant type affected implant load-sharing and specimen translation (p < 0.0001). Implant load-sharing increased across all degeneration-simulating specimen conditions and decreased across the three standard implants (high- to low-stiffness). Translation increased with the three standard implants (trend). The novel implant behaved similarly to the medium-stiffness implant (p > 0.2).

CONCLUSIONS

The novel implant behaved similarly to the medium-stiffness implant in both load-sharing and translation despite having a different design and stiffness. Complex implant design and specimen-implant interaction necessitate pre-clinical testing of novel implants. Further in vitro testing in axial rotation and flexion-extension is recommended as they are highly relevant loading directions for non-rigid implants.

An in vitro model of degenerative lumbar spondylolisthesis

STUDY DESIGN

A biomechanical human cadaveric study.

OBJECTIVE

To create a biomechanical model of low-grade degenerative lumbar spondylolisthesis (DLS), defined by anterior listhesis, for future testing of spinal instrumentation.

SUMMARY OF BACKGROUND DATA

Current spinal implants are used to treat a multitude of conditions that range from herniated discs to degenerative diseases. The optimal stiffness of these instrumentation systems for each specific spinal condition is unknown. Ex vivo models representing degenerative spinal conditions are scarce in the literature. A model of DLS for implant testing will enhance our understanding of implant-spine behavior for specific populations of patients.

METHODS

Four incremental surgical destabilizations were performed on 8 lumbar functional spinal units. The facet complex and intervertebral disc were targeted to represent the tissue changes associated with DLS. After each destabilization, the specimen was tested with: (1) applied shear force (-50 to 250 N) with a constant axial compression force (300 N) and (2) applied pure moments in flexion-extension, lateral bending and axial rotation (±5 Nm). Relative motion between the 2 vertebrae was tracked with a motion capture system. The effect of specimen condition on intervertebral motion was assessed for shear and flexibility testing.

RESULTS

Shear translation increased, specimen stiffness decreased and range of motion increased with specimen destabilization (P < 0.0002). A mean anterior translation of 3.1 mm (SD 1.1 mm) was achieved only after destabilization of both the facet complex and disc. Of the 5 specimen conditions, 3 were required to achieve grade 1 DLS: (1) intact, (3) a 4-mm facet gap, and (5) a combined nucleus and annulus injury.

CONCLUSION

Destabilization of both the facet complex and disc was required to achieve anterior listhesis of 3.1 mm consistent with a grade 1 DLS under an applied shear force of 250 N. Sufficient listhesis was measured without radical specimen resection. Important anatomical structures for supporting spinal instrumentation were preserved such that this model can be used in future to characterize behavior of novel instrumentation prior to clinical trials.

Can low-grade spondylolisthesis be effectively treated by either coflex interlaminar stabilization or laminectomy and posterior spinal fusion? Two-year clinical and radiographic results from the randomized, prospective, multicenter US investigational device exemption trial: clinical article

OBJECT

Posterolateral spinal fusion (PSF) has long been the standard of care for degenerative spondylolisthesis, but less invasive, motion-preserving alternatives have been proposed to reduce the complications associated with fusion while still providing neural decompression and stabilization. The object of the current study is to evaluate the safety and efficacy of coflex Interlaminar Stabilization compared with PSF to treat low-grade spondylolisthesis with spinal stenosis.

METHODS

This is a prospective, randomized, multicenter FDA investigational device exemption (IDE) trial comparing coflex Interlaminar Stabilization with laminectomy and PSF. A total of 322 patients from 21 sites in the US were enrolled between 2006 and 2008 for the IDE trial. The current study evaluated only the subset of patients from this overall cohort with Grade 1 spondylolisthesis (99 in the coflex group and 51 in the fusion group). Subjects were randomized 2:1 to receive decompression and coflex interlaminar stabilization or decompression and posterolateral spinal fusion with spinal instrumentation. Data collected included perioperative outcomes, Oswestry Disability Index (ODI), back and worse leg visual analog scale (VAS) scores, 12-Item Short Form Health Survey, Zurich Claudication Questionnaire (ZCQ), and radiographic outcomes at a minimum of 2 years. The FDA criteria for overall device success required the following to be met: 15-point reduction in ODI, no reoperations, no major device-related complications, and no postoperative epidural injections.

RESULTS

At a minimum of 2 years, patient follow-up was 94.9% and 94.1% in the coflex and fusion control groups, respectively. There were no group differences at baseline for any demographic, clinical, or radiographic parameter. The average age was 63 years in the coflex cohort and 65 years in the fusion cohort. Coflex subjects experienced significantly shorter operative times (p < 0.0001), less estimated blood loss (p < 0.0001), and shorter length of stay (p < 0.0001) than fusion controls. Both groups experienced significant improvements from baseline at 2 years in ODI, VAS back, VAS leg, and ZCQ, with no significant group differences, with the exception of significantly greater ZCQ satisfaction with coflex at 2 years. FDA overall success was achieved in 62.8% of coflex subjects (59 of 94) and 62.5% of fusion controls (30 of 48) (p = 1.000). The reoperation rate was higher in the coflex cohort (14 [14.1%] of 99) compared with fusion (3 [5.9%] of 51, p = 0.18), although this difference was not statistically significant. Fusion was associated with significantly greater angulation and translation at the superior and inferior adjacent levels compared with baseline, while coflex showed no significant radiographic changes at the operative or index levels.

CONCLUSIONS

Low-grade spondylolisthesis was effectively stabilized by coflex and led to similar clinical outcomes, with improved perioperative outcomes, compared with PSF at 2 years. Reoperation rates, however, were higher in the coflex cohort. Patients in the fusion cohort experienced significantly increased superior and inferior level angulation and translation, while those in the coflex cohort experienced no significant adjacent or index level radiographic changes from baseline. Coflex Interlaminar Stabilization is a less invasive, safe, and equally efficacious clinical solution to PSF to treat low-grade spondylolisthesis, and it appears to reduce stresses at the adjacent levels. Clinical trial registration no.: NCT00534235 (ClinicalTrials.gov).