Therapeutic sustainability and durability of coflex interlaminar stabilization after decompression for lumbar spinal stenosis: a four year assessment

The fragility index and reverse fragility index of FDA investigational device exemption trials in spinal fusion surgery: a systematic review

PURPOSE

FDA investigational device exemption (IDE) studies are considered a gold standard of assessing safety and efficacy of novel devices through RCTs. The fragility index (FI) has emerged as a means to assess robustness of statistically significant study results and inversely, the reverse fragility index (RFI) for non-significant differences. Previous authors have defined results as fragile if loss to follow up is greater than the FI or RFI. The aim of this study was to assess the FI, RFI, and robustness of data supplied by IDE studies in spinal surgery.

METHODS

This was a systematic review of the literature. Inclusion criteria included randomized controlled trials with dichotomous outcome measures conducted under IDE guidelines between 2000 and 2023. FI and RFI were calculated through successively changing events to non-events until the outcome changed to non-significance or significance, respectively. The fragility quotient (FQ) and reverse fragility quotient (RFQ) were calculated by dividing the FI and RFI, respectively, by the sample size.

RESULTS

Thirty-two studies met inclusion criteria with a total of 40 unique outcome measures; 240 outcomes were analyzed. Twenty-six studies reported 96 statistically significant results. The median FI was 6 (IQR: 3-9.25), and patients lost to follow up was greater than the FI in 99.0% (95/96) of results. The average FQ was 0.027. Thirty studies reported 144 statistically insignificant results and a median RFI of 6 (IQR: 4-8). The average RFQ extrapolated was 0.021, and loss to follow up was greater than the RFI in 98.6% (142/144) of results.

CONCLUSIONS

IDE studies in spine surgery are surprisingly fragile given their reputations, large sample sizes, and intent to establish safety in investigational devices. This study found a median FI and RFI of 6. The number of patients lost to follow-up was greater than FIand RFI in 98.8% (237/240) of reported outcomes. FQ and RFQ tell us that changes of two to three patients per hundred can flip the significance of reported outcomes. This is an important reminder of the limitations of RCTs. Analysis of fragility in future studies may help clarify the strength of the relationship between reported data and their conclusions.

Decompression and Interlaminar Stabilization for Lumbar Spinal Stenosis: A Cohort Study and Two-Dimensional Operative Video

Background and Objectives: Lumbar spinal stenosis is one of the most common causes of disability in the elderly and often necessitates surgical intervention in patients over the age of 65. Our study aimed to evaluate the clinical efficacy of interlaminar stabilization following decompressive laminectomy in patients with lumbar stenosis without instability. Materials and Methods: Twenty patients with lumbar stenosis underwent decompressive laminectomy and interlaminar stabilization at our academic institution. Clinical outcomes were measured using the visual analog scale (VAS) and Oswestry disability index (ODI) at the 2-month, 6-month, and 1-year postoperative visits, and these outcomes were compared to the preoperative scores. Results: The average VAS scores for low back pain significantly improved from 8.8 preoperatively to 4.0, 3.7, and 3.9 at 2 months, 6 months, and 1 year postoperatively, respectively (p < 0.001). The average VAS scores for lower extremity pain significantly improved from 9.0 preoperatively to 2.7, 2.5, and 2.5 at 2 months, 6 months, and 1 year postoperatively, respectively (p < 0.001). The average ODI scores significantly improved from 66.6 preoperatively to 23.8, 23.3, and 24.5 at 2 months, 6 months, and 1 year postoperatively, respectively (p < 0.001). There was no statistical significance for difference in VAS or ODI scores between 2 months, 6 months, and 1 year. One patient had an intraoperative durotomy that was successfully treated with local repair and lumbar drainage. Another patient had progression of stenosis and had to undergo bilateral facetectomy and fusion. Conclusions: Decompressive laminectomy and interlaminar stabilization in patients with spinal claudication and low back pain is a good surgical option in the absence of instability and may provide significant clinical improvement of pain and functional disability.

Patient Outcomes After Single-level Coflex Interspinous Implants Versus Single-level Laminectomy

STUDY DESIGN

Retrospective cohort analysis.

OBJECTIVE

The aim of this study was to compare postoperative outcomes of Coflex interspinous device versus laminectomy.

SUMMARY OF BACKGROUND DATA

Coflex Interlaminar Stabilization device (CID) is indicated for one- or two-level lumbar stenosis with grade 1 stable spondylolisthesis in adult patients, as an alternative to laminectomy, or laminectomy and fusion. CID provides stability against progressive spondylolisthesis, retains motion, and prevents further disc space collapse.

METHODS

Patients ≥18 years' old with lumbar stenosis and grade 1 stable spondylolisthesis who underwent either primary single-level decompression and implantation of CID, or single-level laminectomy alone were included with a minimum 90-day follow-up at a single academic institution. Clinical characteristics, perioperative outcomes, and postoperative complications were reviewed until the latest follow-up. χ2 and independent samples t tests were used for analysis.

RESULTS

Eighty-three patients (2007-2019) were included: 37 cases of single-level laminectomy (48.6% female) were compared to 46 single-level CID (50% female). CID cohort was older (CID 69.0 ± 9.4 vs. laminectomy 64.2 ± 11.0, P = 0.042) and had higher American Society of Anesthesiologists (ASA) grade (CID 2.59 ± 0.73 vs. laminectomy 2.17 ± 0.48, P = 0.020). CID patients had higher estimated blood loss (EBL) (97.50 ± 77.76 vs. 52.84 ± 50.63 mL, P = 0.004), longer operative time (141.91 ± 47.88 vs. 106.81 ± 41.30 minutes, P = 0.001), and longer length of stay (2.0 ± 1.5 vs. 1.1 ± 1.0 days, P = 0.001). Total perioperative complications (21.7% vs. 5.4%, P = 0.035) and instrumentation-related complication was higher in CID (10.9% vs. 0% laminectomy group, P = 0.039). There were no other significant differences between the groups in demographics or outcomes.

CONCLUSION

Single-level CID devices had higher perioperative 90-day complications, longer operative time, length of stay, higher EBL compared to laminectomies alone. Similar overall revision and neurologic complication rates were noted compared to laminectomy at last follow-up.Level of Evidence: 3.

A minimum 8-year follow-up comparative study of decompression and coflex stabilization with decompression and fusion

The current study aimed to compare the outcomes of decompression and interlaminar stabilisation with those of decompression and fusion for the treatment of lumbar degenerative disease (LDD) at a minimum 8-year follow-up. The current study also aimed to analyse the risk factors of radiographic adjacent segment degeneration (ASD). A total of 82 consecutive patients with LDD who underwent surgery between June 2007 and February 2011 were retrospectively reviewed. Of these patients, 39 underwent decompression and Coflex interspinous stabilisation (Coflex group) and 43 underwent decompression and posterior lumbar interbody fusion (PLIF) (PLIF group). All patients had a minimum of 8-years of follow-up data. Radiographic and clinical outcomes were compared between the groups, and the risk factors of developing radiographic ASD were also evaluated. The Oswestry disability index and visual analogue scale leg and back pain scores of both groups significantly improved compared with the baseline (all P<0.05), and no difference were indicated between the two groups at each follow-up time point (P>0.05). The Coflex group exhibited preserved mobility (P<0.001), which was associated with a decreased amount of blood loss (P<0.001), shorter duration of surgery (P=0.001), shorter duration of hospital stay and a lower incidence of ASD (12.8 vs. 32.56%; P=0.040) compared with the fusion group. The current study indicated that coflex and fusion technologies are safe and effective for the treatment of LDD, based on long-term follow-up data. However, Coflex interspinous stabilisation was revealed to reduce ASD incidence. Under strict indications, Coflex interspinous stabilisation is an effective and safe treatment method.

Determination of Work Relative Value Units for Management of Lumbar Spinal Stenosis by Open Decompression and Interlaminar Stabilization

BACKGROUND

Effective January 1, 2017, open surgical decompression and interlaminar stabilization (ILS) received a Category I Current Procedural Terminology (CPT®) code 22867. The current work relative value units (wRVUs) assigned to the procedure of 13.5 are not reflective of the amount of work involved. During the survey process, CPT® 22867 was erroneously assessed with a percutaneous "sister" code (CPT® 22869), which is performed with no decompression (but within the same new "family") and primarily by nonsurgeons. However, similar CPT® code descriptors assigned to each of these new codes undermined their procedural differences during the survey process and generated confusion among physician survey responders, the American Medical Association/Specialty Society Relative Value Scale Update Committee (RUC), and ultimately the Centers for Medicare and Medicaid Services (CMS) regarding the value of ILS. The resulting physician payment determination for the ILS procedure has had severe deleterious effects on this procedure being offered to lumbar spinal stenosis (LSS) patients. Our independent society-driven survey presents new data that assess the accuracy of the assigned wRVUs for CPT® 22867.

METHODS

An independent survey was driven by the International Society for the Advancement of Spine Surgery (ISASS) in November 2018 and sent to 58 US surgeons with experience performing open decompression with ILS (CPT® 22867) and without financial conflicts of interest as analogous to RUC survey financial disclosure requests. Respondents were asked to compare CPT® 22867 with a list of 10 other comparator CPT® codes reflective of common spine surgeries. The survey presented each comparator CPT® code with its code descriptor and corresponding wRVUs alongside the code descriptor for CPT® 22867. A patient vignette was also provided that describes a typical clinical scenario for the surveyed procedure. Respondents were then asked to indicate which comparator CPT® code on the reference list is most similar to the survey code descriptor and typical patient/service vignette provided, as well as specify estimated wRVUs for CPT® 22867 relative to their selected comparator CPT® code. The surgeons' responses were analyzed to determine comparator CPT® codes and estimated wRVUs.

RESULTS

Among the 28 surgeons who responded to the survey, both open decompression codes (57.1%) and fusion codes (42.9%) were chosen as most similar to the typical patient/service for CPT® 22867. Furthermore, the laminectomy procedure (CPT® 63047) was chosen as the surveyed surgeons' model response for a reference procedure in terms of similar work intensity and time for CPT® 22867. After calculating the difference between the selected comparator codes and estimated wRVUs, nearly all respondents had a positive calculated difference, indicating that surgeons selected wRVUs lower than they deemed appropriate as a result of the listed CPT® codes they were required to use. In the spirit of the Rasch analysis, the regression analysis estimated wRVUs for CPT® 22867 that are greater than its assigned wRVUs (13.5) and its most comparable procedure (CPT® 63047; reference wRVUs: 15.37).

DISCUSSION AND CONCLUSIONS

The survey results indicate that the wRVUs assigned to CPT® 22867 are significantly undervalued at 13.50 and have directly resulted in the underreimbursement for surgeons performing the ILS procedure. This misvaluation of the code has created a supply-and-demand anomaly in which the rate of ILS procedures has flatlined despite increasing rates of fusion procedures and an increasing older population. This anomaly is a cause of concern for policy makers and the health care community for the future of safeguarding patient welfare and procedural innovation. Therefore, understanding the clinical economic impact and appropriately addressing potential misvalued codes, such as the ILS procedure, are critical to protecting the future of patient care.

Interlaminar stabilization offers greater biomechanical advantage compared to interspinous stabilization after lumbar decompression: a finite element analysis

BACKGROUND

Interlaminar stabilization and interspinous stabilization are two newer minimally invasive methods for lumbar spine stabilization, used frequently in conjunction with lumbar decompression to treat lumbar stenosis. The two methods share certain similarities, therefore, frequently being categorized together. However, the two methods offer distinct biomechanical properties, which affect their respective effectiveness and surgical success.

OBJECTIVE

To compare the biomechanical characteristics of interlaminar stabilization after lumbar decompression (ILS) and interspinous stabilization after lumbar decompression (ISS). For comparison, lumbar decompression alone (DA) and decompression with instrumented fusion (DF) were also included in the biomechanical analysis.

METHODS

Four finite element models were constructed, i.e., DA, DF, ISS, and ILS. To minimize device influence and focus on the biomechanical properties of different methods, Coflex device as a model system was placed at different position for the comparison of ISS and ILS. The range of motion (ROM) and disc stress peak at the surgical and adjacent levels were compared among the four surgical constructs. The stress peak of the spinous process, whole device, and device wing was compared between ISS and ILS.

RESULTS

Compared with DA, the ROM and disc stress at the surgical level in ILS or ISS were much lower in extension. The ROM and disc stress at the surgical level in ILS were 1.27° and 0.36 MPa, respectively, and in ISS 1.51°and 0.55 MPa, respectively in extension. This is compared with 4.71° and 1.44 MPa, respectively in DA. ILS (2.06-4.85° and 0.37-0.98 MPa, respectively) or ISS (2.07-4.78° and 0.37-0.98 MPa, respectively) also induced much lower ROM and disc stress at the adjacent levels compared with DF (2.50-7.20° and 0.37-1.20 MPa, respectively). ILS further reduced the ROM and disc stress at the surgical level by 8% and 25%, respectively, compared to ISS. The stress peak of the spinous process in ILS was significantly lower than that in ISS (13.93-101 MPa vs. 31.08-172.5 MPa). In rotation, ILS yielded a much lower stress peak in the instrumentation wing than ISS (128.7 MPa vs. 222.1 MPa).

CONCLUSION

ILS and ISS partly address the issues of segmental instability in DA and hypermobility and overload at the adjacent levels in DF. ILS achieves greater segmental stability and results in a lower disc stress, compared to ISS. In addition, ILS reduces the risk of spinous process fracture and device failure.

Future Studies and Directions for the Optimization of Outcomes for Lumbar Spondylolisthesis

Randomized prospective studies show clear benefits for operative versus nonoperative management of symptomatic lumbar spondylolisthesis, but there is no universally accepted surgical treatment. This article presents options for surgical management of lumbar spondylolisthesis, reviews the clinical trials delineating the role and type of surgical intervention, and explores the directions of future investigations. The next decade will add further clarity to the surgical management of spondylolisthesis, not by randomized prospective trials, but by surgical registries. The power of "big data" offered by registries will likely become the vehicle best suited to amass data on current and novel therapies.

Interlaminar stabilization and decompression for the treatment of bilateral juxtafacet cysts: Case report and literature review

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Lumbar juxtafacet cysts are typically treated by resection alone or resection combined with posterior instrumentation.

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Resection with instrumentation is associated with a lower rate of recurrence but also with increased cost and morbidity.

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We present a case of bilateral juxtafacet cysts causing neurogenic claudication treated with decompression and interlaminar stabilization.

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Complete symptom resolution was sustained at one-year follow-up.

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Decompression followed by interlaminar stabilization may be a reasonable alternative for some patients.

Introduction

Lumbar juxtafacet cysts (JFCs) are a common cause of lumbar radiculopathy which tend to occur in areas of increased facet mobility. While resection alone is a possible treatment, recent publications suggest that laminectomy alone for JFCs may not yield as favorable an outcome as laminotomies reinforced with posterior dynamic hardware. The Coflex^® is a novel interlaminar stabilization device that has been shown to achieve comparable results to rigid fusion in the management of lumbar stenosis in patients with no more than grade one anterolisthesis, and superior performance compared to laminectomy alone when a combined outcome score was used. We describe the combined use of dynamic posterior element fusion with primary cyst resection in the management of bilateral JFCs.

Presentation of case

A 71-year-old man who developed a progressive left L4 radiculopathy along with new urinary incontinence was found to have bilateral L3/4 JFCs causing significant lumbar stenosis and neurogenic claudication. After treatment with primary cyst resection and interlaminar stabilization, the patient experienced complete symptom resolution and was discharged to inpatient-rehabilitation on post-operative day 1.

Discussion

While current recommendations for the management of juxtafacet cysts causing progressive neurologic symptoms include surgical cyst removal and lumbar decompression with or without fusion, the role of dynamic interlaminar stabilization has not been explored.

Conclusion

Direct decompression followed by interlaminar stabilization may represent an alternative for patients to simultaneously benefit from a decompression of their juxtafacet cysts while affording posterior element reconstruction.

Prospective, randomized, multicenter study with 2-year follow-up to compare the performance of decompression with and without interlaminar stabilization

OBJECTIVE

Surgical decompression is extremely effective in relieving pain and symptoms due to lumbar spinal stenosis (LSS). Decompression with interlaminar stabilization (D+ILS) is as effective as decompression with posterolateral fusion for stenosis, as shown in a major US FDA pivotal trial. This study reports a multicenter, randomized controlled trial in which D+ILS was compared with decompression alone (DA) for treatment of moderate to severe LSS.

METHODS

Under approved institutional ethics review, 230 patients (1:1 ratio) randomized to either DA or D+ILS (coflex, Paradigm Spine) were treated at 7 sites in Germany. Patients had moderate to severe LSS at 1 or 2 adjacent segments from L-3 to L-5. Outcomes were evaluated up to 2 years postoperatively, including Oswestry Disability Index (ODI) scores, the presence of secondary surgery or lumbar injections, neurological status, and the presence of device- or procedure-related severe adverse events. The composite clinical success (CCS) was defined as combining all 4 of these outcomes, a success definition validated in a US FDA pivotal trial. Additional secondary end points included visual analog scale (VAS) scores, Zürich Claudication Questionnaire (ZCQ) scores, narcotic usage, walking tolerance, and radiographs.

RESULTS

The overall follow-up rate was 91% at 2 years. There were no significant differences in patient-reported outcomes at 24 months (p > 0.05). The CCS was superior for the D+ILS arm (p = 0.017). The risk of secondary intervention was 1.75 times higher among patients in the DA group than among those in the D+ILS group (p = 0.055). The DA arm had 228% more lumbar injections (4.5% for D+ILS vs 14.8% for DA; p = 0.0065) than the D+ILS one. Patients who underwent DA had a numerically higher rate of narcotic use at every time point postsurgically (16.7% for D+ILS vs 23% for DA at 24 months). Walking Distance Test results were statistically significantly different from baseline; the D+ILS group had > 2 times the improvement of the DA. The patients who underwent D+ILS had > 5 times the improvement from baseline compared with only 2 times the improvement from baseline for the DA group. Foraminal height and disc height were largely maintained in patients who underwent D+ILS, whereas patients treated with DA showed a significant decrease at 24 months postoperatively (p < 0.001).

CONCLUSIONS

This study showed no significant difference in the individual patient-reported outcomes (e.g., ODI, VAS, ZCQ) between the treatments when viewed in isolation. The CCS (survivorship, ODI success, absence of neurological deterioration or device- or procedure-related severe adverse events) is statistically superior for ILS. Microsurgical D+ILS increases walking distance, decreases compensatory pain management, and maintains radiographic foraminal height, extending the durability and sustainability of a decompression procedure.

Clinical trial registration no.: NCT01316211 (clinicaltrials.gov)

Interspinous implants: are the new implants better than the last generation? A review

PURPOSE OF REVIEW

Interspinous process devices (IPDs) are used in the surgical treatment of lumbar spinal stenosis. The purpose of this review is to compare the first generation with the next-generation devices in terms of complications, device failure, reoperation rates, symptom relief, and outcome.

RECENT FINDINGS

Thirty-seven studies were included from 2011 to 2016. Device failure occurred at a mean of 3.7%, with a lower tendency to happen with next-generation IPDs. Reoperations occurred at a lower rate with the next-generation devices, with a mean follow up of 24 months (3.7% vs. 11.1%). The clinical outcome is not influenced by the type of IPD. The long-term functionality of these devices is questionable, with radiologic changes and recurrence of symptoms often seen by 2 years following implantation. Next-generation devices do not appear to be subject to the same "bounce back" effect of symptom re-emergence after several years.

Decompression and coflex interlaminar stabilisation compared with conventional surgical procedures for lumbar spinal stenosis: A systematic review and meta-analysis

BACKGROUND

Decompression plus spinal fusion is one of the most common surgeries for the treatment of degenerative spine disease in older adults. However, complications caused by fusion surgery have been reported in some studies. Recently published studies have reported that coflex is a safe and viable option in the selection of instrumentation for spinal stabilisation. Our meta-analysis was conducted to investigate whether decompression and coflex results in better performance for lumbar spinal stenosis (LSS) patients when compared with decompression and fusion surgery.

METHOD

Web of Science, PubMed, Embase, and the Cochrane Library were comprehensively searched. Ten studies that compared coflex with fusion surgery were included in our meta-analysis. The PRISMA guidelines and Cochrane Handbook were applied to assess the quality of the results published in all included studies to ensure that the results of our meta-analysis were reliable and veritable.

RESULTS

The results of our meta-analysis showed that decompression and coflex was more effective than the control procedure in terms of the Oswestry Disability Index (ODI), length of hospital stay (LOS) and blood loss. However, no significant difference was found in visual analogue scale (VAS) and major device-related complications.

CONCLUSIONS

Compared with conventional decompression plus fusion surgery, coflex was not inferior in terms of functional clinical outcomes, including ODI and VAS pain score. Moreover, coflex showed less blood loss, shorter LOS and similar device-related complications compared to decompression plus fusion surgery. Therefore, the coflex interlaminar stabilisation device was found to be safe and effective compared to decompression plus fusion for the treatment of LSS.

Interspinous dynamic stabilization adjacent to fusion versus double-segment fusion for treatment of lumbar degenerative disease with a minimum follow-up of three years

PURPOSE

The aim of this study was to assess the outcome of symptomatic lumbar degenerative disease treated with topping-off technique (Coflex(™) combined with fusion) and compare two-segment fusion at mid-long term follow-up; and find out whether the topping-off technique can reduce the rate of adjacent segment degeneration (ASD) after fusion.

METHODS

One hundred and fifty-four consecutive patients who received topping-off surgery (76 patients) and two-segment fusion surgery (88 patients) from March 2009 to March 2012 were studied. All patients included in the analysis had a minimum of three years of follow-up. Radiographic and clinical outcomes between the two groups were compared. A logistic regression analysis was used to analyze risk factors for developing radiographic ASD.

RESULTS

Significant differences in clinical outcomes were observed between these two groups at three post-operative years (all, p < 0.05). Compared with the fusion group, the topping-off group showed preserved mobility at the Coflex(™) level (p = 0.000), which is associated with less blood loss (p = 0.000), shorter duration of surgery (p = 0.000) and lower incidence of ASD (Chi-square test, rate topping-off vs fusion = 13.2 vs 26.1 %, p = 0.039). There were no differences in complications between the two groups.

CONCLUSION

Mid-long term follow-up efficacy and safety between topping-off and fusion were similar, while topping-off reduced the rate of ASD. Under strict indications, topping-off surgery is an acceptable alternative to fusion surgery for the treatment of two-segment lumbar disease.