The primary purpose of the study is to measure the change in severity of symptoms and ability to function in every day activities in patients suffering from degenerative lumbar spinal stenosis after treatment with the Aperius® device.

The Intermittent Neurogenic Claudication Treatment with Aperius® (INCA) trial was designed as a multicenter single arm post-marketing study to evaluate the safety and effectiveness of the Aperius® in patients with degenerative lumbar stenosis with symptomatic neurogenic intermittent claudication.

One hundred fifty six patients with a history of Degenerative lumbar spinal stenosis (Lumbar level L1 to L5) at one or maximum 2 levels with symptoms of neurogenic intermittent claudication with or without back pain were included. All patients were followed for 12 months with visits at 48 hours, 7 days, 6 weeks, 6 and 12 months.

Primary effectiveness endpoint was assessed as the mean percentage change from baseline in Zurich Claudication Questionnaire for Symptom Severity at 6 weeks. Other effectiveness outcomes were percentage change in Zurich Claudication Questionnaire scores (ZCQ), Quality of laife Questionnaire scores (called EuroQuol 5D or EQ-5D), Visual Analogue Scale (VAS) pain scores (back, leg and buttock groin pain), pain medication and changes in walking distance from baseline to follow-up. Procedure and device related Serious Adverse Events were assessed throughout the complete 12 month follow-up period.

Inclusion Criteria:

• History of Degenerative Lumbar Spinal Stenosis (Lumbar spine level from L1 -L5), confirmed by Magnetic Resonance Imaging (MRI) at one or maximal two levels, with symptoms of intermittent neurogenic claudication.
• Leg / Buttock / Groin pain, with or without back pain, relieved by flexion. If back pain is also present, it must be partially relieved when flexed.
• Able to sit for 50 minutes without pain.
• Able to walk a distance of 20 meters without pain.
• Patient states availability for and willing to perform all follow -up examinations.
• Patient signed informed consent form.
• Adults (minimum 21 years of age).

Exclusion Criteria:

• Previous lumbar surgery.
• Unremitting pain (leg/buttock/groin/back) in any spinal position.
• Axial back pain without leg/buttock/groin pain.
• Significant lumbar instability at the affected level: spondylolisthesis greater than grade 1 on a scale from 1-4.
• Objective motor deficit.
• Significant peripheral neuropathy by nerve conduction velocity tests (peroneal and sural nerves) according to the investigator.
• Cauda equina syndrome, defined as neural compression causing neurogenic bowel (rectal incontinence) or bladder dysfunction (retention or incontinence).
• Spinal Stenosis with clinical symptoms at one or more levels outside the L1-L5 lumbar region.
• Severe symptomatic Spinal Stenosis requiring immediate surgical decompression,according to the investigator or lumbar spinal stenosis at more than 2 levels.
• Lumbar Spinal Stenosis, caused by tumors, metastasis or Paget's disease.
• Vascular claudication and severe peripheral vascular disease. (Diminished dorsalis pedis or tibial pulses) that limits walking.
• History of primary or secondary osteoporosis defined as a DXA scan (=dual energy x-ray absorptiometry) of the hip showing T-score (=the number of standard deviations above or below the mean for the patient's age, sex and ethnicity) of more than 2.5 standard deviation below the mean in the presence of one or more fragility fractures.
• Active systemic infection or local infection at the level to treat.
• Major Depression according to Diagnostic and Statistical Manual of Mental Disorders (DSM) IV criteria.
• Dementia and/or inability to give informed consent.
• Unable to complete the study.
• Pregnancy and breastfeeding.

All Adverse events were gathered as from the moment the first patient entered the study on November 20, 2006 until the last patient's completed the last visit on May 21, 2009 with a total study duration of 30 months.

All serious adverse device effects are listed below