Lower Back Pain – Fusion 1

LBP-fusion1
Title: Lumbar Arthrodesis for the Treatment of Back Pain – Current Concepts Review

Reference: JBJS Volume 81-A, Number 5, May 1999
– Hanley, E.N., David, S.M., Dept of Orthopaedic Surgeyr, Carolinas Medical Centre, Charlotte, North Carolina

Main Message

– Much has been published on arthrodesis of the lumbar spine; most has used nonstandardized criteria for inclusion, and have used nonvalidated outcomes. This review attempted to determine which treatments are REASONABLE, which are UNREASONABLE, and those that are experimental. Ie. the literature kinda sucks, but some things can be gleaned from it. Some improvement occurs as a result of operative treatment in about 75% of patients (a generous number), but major or complete relief of pain and recovery of function are seen in less than 50% or less.

Points of Interest

Etiology of Low Back Pain

Facets
– the facets have a controversial role. Facet blocks have had disappointing success as a therapeutic modality. �It is believed that so called facet syndrome is much less common cause of low back pain than are problems related to the intervertebral disk�.
– the predictive value of facet blocks for the success of lumbar arthrodesis is also questionable.
Discs
– MRI abnormalities exist in a significant (one/third) proportion of the normal population (Boden, 1990)
– the outer annulus is highly innervated, as is the endplate, and PLL. The outer layer of the annulus has most often been implicated as the tissue causing axial low back pain. Some authors have stimulated this layer (and the PLL) and have produced typical symptoms of back pain.
– the hypothesis that the disc is the source of pain is also supported by the observation that in the cervical spine, resolution of symptoms are sometimes seen with excision of the disc without arthrodesis.

Degenerative Instability

– this, like �facet pain�, is also thought to be uncommon. Poor outcome in spinal fusion has not been found to be associated with pseudarthrosis, so �abnormal motion� is not necessarily the problem.
– AAOS Definition of segmental instability: �an abnormal response to applied loads, characterized by motion in the motion segment beyond normal constraints�.
– Kirkaldy-Willis on the pathology of degeneration: 3 phases – Phase 1 is dysfunction (tearing of the annulus fibrosus, degeneration of the nucleus, arthropathy of the facets), phase 2 is instability (laxity of facets and discs), phase 3 is restabilization (formation of osteophytes and facet hypertrophy).

– the concept of segmental instability may be related to, but differs from, the diagnosis of so-called discogenic back pain (pain related to disc degeneration).
– it is difficult to quantify instability on x-ray, and there is no agreement on what is abnormal motion on flexion/extension films.

Diagnostic Studies

Provocative Discography – controversial. Varied results on the predictive value of discography in spinal arthrodesis.
1995 NASS position paper on discography indicates that it is supported for determining which disc level or levels reproduce the pain in those with non-radicular symptoms, or localizing discogenic sources of persistent pain after a previous unsuccessful procedure on the lumbar spine. They advocate using CT and MRI to support the discogram findings, and recommend against using discogram alone.

Non-Operative Treatment
– Strong evidence supports the use of NSAIDs and muscle relaxants in acute LBP. Evidence supports the use of excercise, back school, and manipulation in chronic LBP. Bed rest for no more than 2 days is advisable for severe acute pain.