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Interv Neuroradiol. 2016 April; 22(2): 217–226.
Published online 2016 January 14. doi:  10.1177/1591019915622163
PMCID: PMC4984346

Degenerative lumbar spinal stenosis treatment with Aperius™ PerCLID™ system and Falena® interspinous spacers: 1-year follow-up of clinical outcome and quality of life

Abstract

Purpose

Evaluation of the efficacy of the Falena® and Aperius™ PerCLID™ interspinous devices in the treatment of degenerative lumbar spinal stenosis with neurogenic intermittent claudication refractory to conservative treatment.

Materials and methods

We retrospectively analyzed data from 24 patients (20 male and 4 female patients; 61 ± 7 years old), treated with an implantation of the AperiusTM PerCLID™ system, and from 35 patients (29 male and 6 female patients; 65 ± 9 years old) treated with the Falena® interspinous device.

Patient pain intensity was evaluated by a 10-point visual analog scale (VAS), with a score (ranging from 0 = no pain to 10 = unbearable pain) that was collected before the procedure, at baseline; and at months 1, 6 and 12 after the interventional procedure. The assessment of quality of life (QOL) impairment was evaluated by the Oswestry Disability Index (ODI) questionnaire, which was administered beforehand at baseline; and at months 1, 6 and 12 after the interventional procedure. The vertebral canal area was measured by magnetic resonance imaging (MRI) scans before the treatment and at the one-year follow-up.

Results

All patients completed the study with no complications. Both the Falena group and Aperius group of surgery patients showed a statistically significant reduction of their VAS and ODI scores at the 6- and 12-month follow-up (p < 0.0001). A statistically significant increase in the vertebral canal area was observed both in the group that received Falena (p < 0.0001) and in the group that received Aperius (p = 0.0003). At the 1-year follow-up, we observed that there was a higher increase of vertebral canal area in those patients whom were treated with the Falena device (p < 0.001).

Conclusions

The implantation of Falena® and Aperius™ PerCLID™ interspinous devices is an effective and safe procedure, in the medium term.

Keywords: Degenerative disease, interspinous devices, interspinous spacers, lumbar spinal stenosis, medical devices, neurogenic intermittent claudication, percutaneous interspinous device, spinal surgery, vertebral canal

Introduction

Lumbar spinal stenosis (LSS) is a clinical entity characterized by a narrowing of the vertebral canal and/or intervertebral foramen, determining the onset of a neurogenic claudication, due to compression of the spinal nerves and associated vasculature.1

This condition can be either primary, caused by congenital abnormalities or disorders of postnatal development,1 or most frequently, secondary to acquired degenerative changes such as osteoarthrosis, intervertebral disc bulges or herniation, facet joint degeneration, hypertrophy of the ligamentum flavum and degenerative spondylolisthesis.2,3

LSS has been shown to be prevalent in 27.2% of the population, in the Framingham study.4 Secondary forms generally become symptomatic in the fifth to sixth decades of life, with a prevalence in the male gender.5

The symptoms observed in LSS involve neurogenic claudication, radiculopathy due to nerve root compression,5 low back pain and non-radicular referred lower extremity pain.6 Amundsen et al.7 report that, in patients affected by spinal canal stenosis, the most frequent symptoms are: back pain (95%) followed by neurogenic claudication (91%), lower limb pain (71%), weakness (33%), urinary incontinence and uncontrolled defecation (12%).

Therapeutic approaches in mild or moderate symptomatic LSS involve conservative treatments, such as medical therapy with analgesic and anti-inflammatory drugs, physical therapy, and percutaneous discectomy;3 in patients with severe symptoms, surgery is preferred.8 Interspinous spacers (IS) are implants that were proposed as a less invasive alternative to the surgical approaches, providing dynamic spinal stabilization with less risk of adjacent segment degeneration.9,10,11 IS is eligible for all patients with symptoms due to LSS, patients with lower back pain with or without radicular involvement.9,10,11 Some authors consider as an essential condition the failure of all conservative therapies for a considerable period: usually six months is accepted in literature.9,10,11 The presence of permanent motor deficit or degenerative spondylolisthesis are exclusion criteria.9,10,11

In this study, we report multicentric data from patients implanted with Falena® and Aperius™ PerCLID™ IS during 1-year clinical follow-up.

Materials and methods

Study design

We retrospectively analyzed data from 59 patients affected by symptomatic degenerative LSS. There were 24 patients (20 male and 4 female; mean age ± SD: 61 years ± 7) who were treated with implantation of the AperiusTM PerCLID™ system (Medtronic-Sofamor Danek, Memphis, Tennessee, USA), which we called the Aperius group, and 35 patients (29 male and 6 female; mean age ± SD: 65 ± 9 years) who were treated with the Falena® interspinous device (Mikai, Genova, Italy) forming the Falena group.

Patient population and preoperative management

This study was approved by the internal ethical committees of the two involved centers. Informed consent was obtained from all patients. The diagnosis, selection of patients and treatment indications were made by an interventional radiologist on the basis of clinical history, physical examination and imaging findings.

All patients were eligible if they had an age older than 50 years and if there was a radiological diagnosis of symptomatic degenerative LSS. Symptoms involved neurogenic claudication and leg, buttock or groin pain, with or without back pain while standing or walking. All treated patients failed previous conservative treatment for at least six months of analgesics and/or anti-inflammatory drugs, physical therapy and epidural injections of corticosteroids and/or anesthetics. Their clinical diagnosis was confirmed in all cases by magnetic resonance imaging (MRI) scans.

Our exclusion criteria were: permanent motor deficit, cauda equina syndrome, previous lumbar surgery, spondylolisthesis at the affected level, pathological fractures and/or severe osteoporosis, Paget’s disease, vertebral metastasis, body mass index (BMI) of >40 kg/m2, local or systemic infections, vertebral fusion and previous corticosteroid therapy for >1 month within 6 months before treatment. Finally, a contra-indication to IS implantation was severe osteoarthritis, affecting facet joints or vertebral bodies, with bone bridges between each other.

Percutaneous procedure, operative technique and devices

All procedures were performed in an angiographic suite under fluoroscopic computed tomography (CT) guidance (Allura Xper FD 20; Philips Healthcare, Best, The Netherlands) with the patient in the prone position, with the spine extended.

Antibiotic therapy with Augmentin (GlaxoSmithKline, Verona, Italy) was administered for three days before the treatment and three days after it.

After localizing the operative segment fluoroscopically, paraspinous local anesthesia was administered with 10 mL of lidocaine 2% (AltaSelect, Verona, Italy) and 10 mL of naropine 7.5% (B. Braun Melsungen AG, Melsungen Germany).

In the Falena group, a sagittal skin incision over the spine of approximately 4 cm was performed; and then the musculature was dissected to the level of the laminae and facets, preserving the supraspinous ligament. A curved dilator was inserted in the interspinous space, piercing the interspinous ligament. Then, a sizing distractor was inserted in the same area, to determine the implant size. Using an insertion instrument, the device was inserted under fluoroscopic guidance into the interspinous space. Once the skin incision was closed, the anteroposterior and lateral fluoroscopy views were taken, to verify the proper positioning of the implant.12

A similar procedure was performed for the patients in the Aperius group. A unilateral skin incision was made about 10 cm from the midline. The Aperius™ PerCLID® system is composed by a set of color-coded distractor trocars of increasing sizes (8 mm, 10 mm, 12 mm and 14 mm) that allow for increasing the interspinous space. There are also four color-coded pre-loaded inserters (8 mm, 10 mm, 12 mm and 14 mm) with a curved shape, to facilitate the positioning of the system. The 8-mm distractor trocar, which is first introduced into the skin lesion, has a sharp pointy tip to pierce the interspinous ligament. After the correct distractor was inserted to determine the implant size, the corresponding color-coded preloaded inserter was introduced in the same area, to release the device (Figure 1).

Figure 1.
A 65-year-old male treated with implantation of two Aperius™ PerCLID™ interspinous devices, for L3-L4 and L4-L5 lumbar spinal stenosis. Figure 1 shows the main steps of the procedure, under fluoroscopic guidance: (a) Paraspinous local ...

Patients were allowed to mobilize independently and were discharged the day after the procedure, in the absence of clinical complications.

Clinical assessment and follow-up

Follow-up was carried out during a period of one year after the interventional procedure, by clinical examination. Pain intensity was evaluated by a 10-point visual analog scale (VAS) score (where 0 means ‘no pain’ and 10 means ‘unbearable pain’), collected before baseline and at one month, six months and one year after the interventional procedure.

Assessment of quality of life (QOL) impairment was evaluated by an Oswestry Disability Index (ODI) questionnaire, administered before (at baseline) and at one month, six months and one year after the interventional procedure. All patients presented moderate-to-severe disability at the first visit.

CT examination (Lightspeed VCT, GE Healthcare Medical Systems, Milwaukee, WI, USA) and orthostatic MRI (G-Scan, Esaote, Italy) were performed one month, six months and one year after the interventional procedure; to evaluate the vertebral segment treated, and to assess the correct positioning and stability of the interspinous device (Figures 2 and and3).3). In all patients, the vertebral canal area was measured by using a freehand region of interest on the MRI scans, obtained before the treatment, and at the one-year follow-up (Figures 4 and and5).5). The imaging evaluation was entrusted to an interventional radiologist different from the physician whom was enrolling patients.

Figure 2.
A 63-year-old male treated with implantation of the Falena® device at the level of L4-L5; 1-year control. Virtual reconstruction of CT scans with SSD protocol on postero-anterior view. The images show the correct positioning of the device.
Figure 3.
A 63-year-old male treated with implantation of the Falena® device at the level of L4-L5; 1-year control. Virtual reconstruction of CT scans with the SSD protocol on the sagittal view. The images show the correct positioning of the device.
Figure 4.
Pre- procedural T2-weighted axial MRI scans. Vertebral canal area measurement.
Figure 5.
Post- procedural T2-weighted axial MRI scans. Vertebral canal area measurement.

During the screening period, the use of analgesic drugs was recorded.

Statistical analysis

The comparison of the VAS and ODI score values, as well as the vertebral canal diameter, was performed among the single groups at different follow-up times, using the Wilcoxon matched pairs signed-rank test, with 2-tailed p-values and a 95% CI. The comparison of the VAS and ODI score values, as well as the vertebral canal diameter obtained from both groups, was performed using the Mann-Whitney t-test with 2-tailed p-values and a 95% CI.

Results

No deaths occurred during our observational period. The overall statistics of the VAS and ODI score values obtained from both groups are shown in Tables 114.

Table 1.
VAS score values statistics of the Falena Group.
Table 2.
VAS score values statistics of the Aperius Group.
Table 3.
ODI score values statistics of the Falena Group.
Table 4.
ODI score values statistics of the Aperius Group.

Both the VAS and the ODI scores were reduced in a statistically significant manner at one month (p < 0.0001), six months (p < 0.0001) and 12 months (p < 0.0001), in the patients in the Falena group. A similar result was obtained in those in the Aperius group, with a statistically significant reduction of the VAS and ODI scores at one month (p < 0.0001), six months (p < 0.0001) and 12 months (p = 0.0075). A statistically significant increase in the vertebral canal area at the treated level was observed both in the Falena group (p < 0.0001) and in the Aperius group (p = 0.0003).

Both the VAS and ODI score value reductions after the treatment resulted in statistically significant changes among the patients treated with the Falena® device, as compared with the ones treated with the Aperius™ device (p = 0.0112 for VAS and p = 0.011 for ODI), with the difference being maximum at one-month follow-up, but minimum at the one-year follow-up (Figures 6 and and77).

Figure 6.
This graphic shows the decrease of the VAS score values in patients treated with both the Falena® and the Aperius™ PerCLID™ interspinous devices.
Figure 7.
This graphic shows the decrease of the ODI score values in patients treated with both the Falena® and the Aperius™ PerCLID™ interspinous devices.

An overall statistical analysis of the vertebral canal area measurements obtained from both groups at one year (Tables 5 and and6)6) demonstrated a statistically significant higher increase in the vertebral canal area diameter in the patients treated with the Falena® device, compared with the subjects treated with the Aperius™ device (p < 0.001) (Figure 8).

Figure 8.
The graphic shows a statistically significant higher increase of the vertebral canal area diameter in the patients treated with the Falena® device at 1 year, compared with the subjects treated with the Aperius™ PerCLID™ device. ...
Table 5.
Vertebral canal area statistics of the Falena Group.
Table 6.
Vertebral canal area statistics of the Aperius Group.

Discussion

Degenerative LSS is a frequent cause of lower back and leg pain, and represents the most common indication for lumbar spinal surgery in the elderly population. Clinical experience has also demonstrated the effectiveness of conservative treatments in patients with LSS.3 Some trials13,14 instead documented a similar outcome, with surgery as the first therapeutic choice. A long-term follow-up study among patients with LSS shows a similar outcome between those patients initially treated surgically, and those patients whom were only treated with conservative therapy.13

Chang et al.14 evaluated the effects and long-term results of surgical treatment in patients with LSS, with a better outcome seen in these patients than in the non-surgically treated patients: The authors also concluded that the benefits of surgery diminish over a long-term follow-up, with no significant differences remaining when compared to patients treated non-surgically.

Amundsen et al.15 suggest an initial conservative approach for many patients, followed by surgical treatment in those with unsatisfactory results. While offering improvement in QOL, surgical treatment also has the potential for significant peri-procedural and post-operative complications, often associated with any surgery and not specific for lumbar spine surgery.16

Before the introduction of IS, surgical decompression, with or without arthrodesis, represented the gold standard of treatment for moderate-to-severe lumbar spinal stenosis when conservative therapies failed.12 IS have been introduced for the treatment of degenerative LSS, with the aim to obtain a dynamic motion-preserving decompression, providing an unloading distractive force and stabilization. The advantages are the minor invasiveness of the procedure, without disruption of the normal anatomical structure, fewer procedural complications, a shorter procedural time and less degeneration of the contiguous vertebral segments.9,17

Nowadays, the X-Stop® device is the most examined in literature.1824 The X-Stop® device is implanted with a 5–7 cm skin incision on the midline and without the removal of the interspinous ligament. Zucherman et al.20 report the results obtained in 191 patients with symptomatic degenerative LSS whom were treated either with conservative therapy or with X-Stop® implantation. During a 2-year follow-up, the authors20 observed significantly better results in the patients treated by the operation. MRI studies report a significant increase in the foraminal and vertebral canal areas after X-Stop® implantation, without significant changes in the intervertebral disc heights25 and lumbar spine movement, after implantation.26

Recently, a rigid IS device called the Aperius™ PerCLID™ has been introduced into clinical practice. This IS device has an implant core manufactured of titanium alloy (TiAl6V4 alloy) and an external shell composed of commercially pure titanium. It can be implanted without the removal of the interspinous ligament, obtaining decompression through interspinous process distraction; and like the X Stop®, it is possible to implant up to two devices at consecutive levels. It has the benefit of being a completely percutaneous technique, under local or spinal anaesthesia. Fabrizi et al.27 document the procedural time as 7 minutes, in 260 patients treated with the Aperius™ PerCLID™. In a multicentric prospective study,28 156 patients were treated with the same system. An improvement in painful symptomatology and in QOL was recorded after the 12-month follow-up.28 Surace et al.29 show the effectiveness and the safety of the Aperius™ PerCLID™ device in 36 patients. In all, the study authors documented a low rate of complications, which included fractures of the spinous process and the necessity to remove the IS with passage to an open surgery.

The Falena® device is an IS indicated for surgical decompression with a minimally invasive approach in patients with symptoms that are secondary to spinal and radicular stenosis. This device is composed of a winged structure, formed by a main pin with two wings at the extremities and a cap that allows a traumatic crossing of the interspinous ligament, and a C-spring available in a range of height sizes (e.g. 8, 10, 12 and 15 mm). The wing structure of the device is of a titanium alloy, the C-spring is out of PEEK OPTIMA® polymer, widely used in orthopedics for its mechanical properties (i.e. bone-like stiffness, high biocompatibility and good resistance to wear). The Falena® is implanted with a percutaneous technique, without the removal of the sopraspinous ligament; and it has similar characteristics of the Aperius™ PerCLID™ 1: a low procedural time, and the possibility of using two devices at consecutive levels.

Our post-operative results confirm the effectiveness of treatment with the Falena® and Aperius™ PerCLID™ percutaneous interspinous devices, in terms of pain reduction, functionality and QOL improvement; with evidence of there being greater efficacy with the implantation of the Falena® device. Regarding the Falena-group, our evaluation of the data observed during the one-year follow-up, in terms of pain reduction and QOL improvement, confirms the results that we obtained in an earlier study on a less numerous cohort.12 With respect to the Aperius-group, we have obtained post-operative results that are substantially similar to those described in the literature with the use of the same device.

According to our data, it is confirmed that treatments with both the Falena® and Aperius™ PerCLID™ result in a significant reduction of symptoms, secondary to LSS at one month with further stabilization after six months, attributable to the healing of surgical access and reduction of the inflammatory reaction secondary to the mechanical distraction of the spine. These effects remain remarkably stable for up to approximately six months from the treatment in all patients, with only a slight reversal of the trend and a modest recovery of symptoms by the end of the follow-up period; however, despite a slight recurrence of symptoms in both groups, the patients treated by the Falena® implantation presented a lower persistence or recurrence of symptoms at one year. This difference can be justified by the evidence of a greater restoring of vertebral channel amplitude in the patients implanted with the Falena® device.

Overall, our results were aligned to those reported in a previous study evaluating the middle-term effects of degenerative LSS treatment with the X-Stop interspinous device, sharing some technical analogies with the devices that we use.30 The main advantage of our study was to compare two different percutaneous interspinous devices’ implantation. We demonstrated how interspinous decompression with both the Aperius™ and the Falena® interspinous devices has a favorable outcome in the middle term.

Because these percutaneous interspinous devices were not implanted adjacent to the nervous structures such as spinal cord or nerve roots, there is a minimal risk of neurologic deficit after treatment; so no complications were observed in our trial (also thanks to the experience of the operators). Other authors31 report complications, mainly spinous process fractures, attributed either to reduced bone strength in osteoporotic patients or distractive effect. Although we did not compare the outcomes of percutaneous IS implantation with a surgical decompression technique, our evidence confirmed how this procedure is likely safer in skilled hands, if compared with the incidence and severity of complications associated with surgical decompression treatment that are cited in the literature.20,32

In 18 patients (51%), we observed an alteration of the cortical shape with the bony indentation of the spinal processes, especially in the upper ones (Figure 9). As is highlighted in the literature, these effects might be due to the microtraumatic mechanical effect of IS.26 It can be assumed that the occurrence of this complication can be reduced by modifying the morphology and the mechanical characteristics of the devices and the hardness of the materials used. It should be emphasized that the interspinous devices that we used are available in different sizes, in order to be adapted as much as possible to the anatomical characteristics of the patient. Regarding the Falena® device, we note that it has a shape designed to maximize the contact surface with the spinal process bone, with the intent to reduce spinal process indentation and the occurrence of fracture; however, having regard for the occurrence of this complication in our patients, it can be assumed that there is also a long-term risk of spinous process fractures with this type of device.

Figure 9.
A 71-year-old male treated with the implantation of a Falena® device at the level of L4-L5 and 1-year control. The CT evaluation with sagittal MIP view with bone window shows an alteration of cortical shape of the spinal processes, with bone indentation ...

Bone remodeling of the spinous process may be at the origin of a restenosis with a recurrence syndrome. For preventing those events, Manfrè33 obtained good results with prophylactic percutaneous CT-guided posterior arch augmentation, with a PMMA (Polymethylmethacrylate) cement injection into the spinous process. In our opinion, it could be a good therapeutic strategy also if there were no cases of restenosis due to bone remodeling recorded in our multi-centric study.

We evaluated by orthostatic MRI examination all the patients treated with interspinous device implantation. A diagnostic value for upright MR scans was proven by evaluation of positional-dependent problems of the spine, such as degenerative LSS.25,26,34,35 Because previous studies in the literature demonstrated no significant correlation between imaging appearance and the level of disability in patients with LSS, and that neither the initial radiologic grade of LSS nor the postoperative radiographic changes correspond directly to clinical symptoms,5,36 we have not statistically correlated the MRIs with the clinical data. Imaging findings demonstrate that there is a statistically significant variation of the vertebral canal area after implantation, justifying the stabilization of symptoms.

Our study had some limitations. We did not refer to a control group treated with conservative therapies nor surgery. A prospective, double-blind controlled trial for each IS is needed.

Finally, it is possible to conclude that IS implantation is an alternative therapeutic choice to surgery, in patients with degenerative LSS. For the surgeon or the interventional radiologist, the choice of the correct device is very important to make, according to its mechanical features and properties. We documented implantation of both the Falena® and the Aperius™ PerCLID™ percutaneous IS as a minimally invasive, effective and safe procedure. In fact, we recorded a reduction of symptoms and an improvement in QOL, in the absence of major complications, during the 1-year followup.followup.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

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