Table 1. Lumbar spinal stenosis/GPi study—eligibility criteria.

Inclusion criteria

50 years of age or older

Present with complaints of neurogenic claudication for at least 3 months. Neurogenic claudication as defined as pain, numbness and/or fatigue below the gluteal line with or without back pain (if back pain present, leg pain is greater than back pain) that is precipitated by walking and alleviated by sitting or lumbar flexion

Grades C or D stenosis as defined by Schizas [2010] indicating occlusion (absent CSF signal) of the central lumbar spinal canal at one or two levels on T2 weighted MRI

Be medically suitable for single or dual-level spinal decompression surgery

Have not improved with non-surgical treatment (e.g., physical therapy, injections, stretching, exercises)

Exclusion criteria

Women who are pregnant

Under workers compensation

Serious spinal pathology including cancer, infection, cauda equine syndrome, spinal fracture, inflammatory arthritis

Present with active Paget’s disease of the spine;

Previous lumbar spinal surgery at the same levels

Motor deficit related to lumbar compression [Medical Research Council (MRC) grades 0–4] and the motor deficit interferes with walking ability

Presence of known or demonstrated peripheral vascular disease-causing vascular claudication, i.e., claudication accompanied by absent foot pulse or vascular insufficiency detected with Doppler ultrasound or CT angiography

Presence of significant lumbar scoliosis (Cobb angle >25°) or other spinal deformities

Presence of lumbar instability defined as more than 4 mm or 10 degrees of angular motion (at affected or adjacent level) between flexion and extension on upright lateral radiographs (to exclude patients who might need to undergo concurrent surgical fusion)

Meyerding classification grade 2 or greater spondylolisthesis

Symptomatic hip disease with symptoms reproduced with external or internal rotation of the hip joint

Cognitive impairment or inadequate English language skills that interfere with patient’s ability to give fully informed consent or complete the baseline or follow-up assessments

GPi, Gait Posture index; CSF, cerebrospinal fluid.