Surgery appears to lead to better outcomes if there are ongoing symptoms after three to six months of conservative treatment.  Laminectomy is the most effective of the surgical treatments.  In those who worsen despite conservative treatments surgery leads to improvement in 60–70% of cases.  Another procedure using an interspinous distraction device known as X-STOP was less effective and more expensive when more than one spinal level is repaired.  Both surgical procedures are more expensive than medical management.