Some studies show the longer the fusion, the worse the results. Others claim that choosing the right patient determines the outcome. For a successful fusion of any length, there should be no history of psychologic problems. Patients with a spinal fracture, infection, or tumor should not be fused either.
There are two factors to look at: 1) patient satisfaction after the operation and 2) success rate of the fusion itself. Doctors agree that a successful fusion doesn't always mean the patient is happy. Pain and loss of function can occur even when the fusion appears perfect. Quality of life (QOL) goes down for most patients in pain who can't resume their normal activities.
A new study compared two groups of patients with lumbar spinal fusion. One group had a short fusion (one to two levels) while the second group had a long fusion (three to five levels). Both groups had the same good results when reporting on QOL. The long fusion group had fewer successful fusions and needed a second surgery more often.