Table 1 Inclusion and exclusion criteria.

- Age ≥50 years old

- ≥3 Months neurogenic intermittent claudication, as noted by leg/buttock/groin pain with or without back pain or fatigue in the legs provoked by walking. Leg/buttock/groin pain or fatigue needs to be relieved by lumbar flexion

- Narrowed lumbar spinal canal, nerve root canal or intervertebral foramen at one or more levels confirmed by MRI

- Regular indication for surgical decompression

- Signed informed consent

Exclusion criteria

- Cauda equine syndrome

- Paget's disease, severe osteoporosis or metastasis to the vertebrae

- Significant scoliosis (Cobb angle > 25 degrees)

- Previously laminectomy at the same level, has degenerative or lytic spondylolisthesis ≥ grade 2 (on a scale 1 to 4) at the affected level or significant instability of the lumbar spine

- Severe comorbid conditions that increase the risk to the patient or interfere with the evaluability of this study (e.g. severe ischemic heart disease, musculoskeletal or neurological conditions impairing walking ability, cognitive impairment (MMSE <25 points)

- Unable to read or write Dutch