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Is the Facet Syndrome a Myth?
Lumbar facet syndrome is a very
convenient diagnosis for mechanical low back pain (LBP). The
signs1,2 of a classic facet syndrome are: pain on lumbar hyperextension
and decreased range of motion in any plane but especially in
extension and rotation, local facet tenderness, absence of neurologic
deficit or root tension signs; on lumbar flexion there may be
relief, and straight-leg raising may or may not be normal. Pain
is usually of a deep aching variety and may extend to the buttock,
hip, and even below the knee but not into the foot. But most
of these symptoms and signs may also refer to pain of discogenic
origin.2
"The function of the lumbar
apophysial joints is to allow limited movement between vertebrae
and to protect the discs from shear forces, excessive flexion,
and axial rotation."3
Structures in the lumbar spine
that receive a nerve supply are the zygapophysial joints, the
ligaments of the posterior elements, the paravertebral muscles,
the dura mater, the anterior and posterior longitudinal ligaments,
and the intervertebral disks.4 It becomes clear that functional
tests cannot specifically stress the facet joints. Firmly holding
the patient's hips and pelvis, and asking the patient to bend
forward to determine if relief occurs, to help pinpoint a facet
involvement or creating pain on lumbar extension versus flexion
cannot specifically incriminate a facet since all of the tissues
mentioned above will also be stressed. While the facet joints
are part of the picture of mechanical LBP, and chiropractic adjustments
move zygapophysial joints, there are, of course, many other factors
to be considered as to the reason patients experience relief
from adjustments.
Unfortunately, at our present
state of knowledge, the diagnosis for LBP or for that matter
any diagnosis incriminating a mechanical cause for LBP (as differentiated
from, for example, a herniated disk compressing a specific nerve)
is speculative. Nachemson states that "although today there
is a better understanding of pain, the pathomechanism of low
back pain is unknown."5 He goes on to state that orthopedic
surgeons who operate on patients with ill-defined back syndromes
should realize that rarely are diagnoses scientifically valid,
nor is the effectiveness of surgery proven by acceptable clinical
trials.
While most authorities agree
that the facet joint capsule has free nerve endings and is a
probable source of pain, according to Jackson2 and others,1,6
the "diagnostic capabilities for testing the presence of
a facet syndrome have been proven invalid."
A common method for diagnosing
lumbar pain are diagnostic blocks where an anesthetizing agent
is injected to determine if pain is relieved. According to Jackson,2
who examined the literature and has performed three separate
studies of his own regarding the injection of facet joints, the
facet is not a common or clear source of significant pain and
the facet syndrome is not a reliable clinical diagnosis.
While many studies involving
facet injection have been favorable, Jackson states that there
are very few randomized controlled prospective studies. He states
that the facet joint can only hold about 1-2 ml and many studies
using more than that amount rupture the capsule and spreads the
anesthetic to outlying areas. Jackson2 in one study evaluated
390 patients with facet joint injections. He found that patients
with more pain on lumbar extension and rotation did not get more
pain relief after facet injection. He concluded that more than
90 percent of the patients with the signs of facet syndrome,
did not respond better to facet injection.
Jackson2 quotes a study by Lorenz
et al.,7 which demonstrates that the upper lumbar facets L2-L3
in the lumbar neutral and extension positions have higher compressive
loads than the L4-L5 level. He uses this argument to prove that
facets are not primary sources of pain since clinically most
back pain occurs in the lower L4-L5 levels. Of course he does
not mention the fact that due to greater disk degeneration at
the L4-L5 level the pressure on the L4-L5 facets will increase
accordingly.8
I suppose since no one at the
present time can pinpoint the exact source of pain in the mechanical
low back problem, it is easy to prove that no one location is
the source of the pain. For years there has been an argument
between the disk and the facets as the main source of pain. Until
someone can definitely prove that the facet is not a principle
cause, I, for one, will be using facet syndrome as a plausible
diagnosis.
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- References
- 1.Lippitt AB: The facet joint
and its role in spine pain management with facet joint injections.
Spine, 9:746-750, 1984.
- 2.Jackson RP: The facet syndrome,
myth or reality? Clin Orthop., 279:110-121, 1992.
- 3.Adams MA, Hutton WC: The mechanical
function of the lumbar apophysial joints. Spine 8:327-330, 1983.
- 4.Bogduk N, Twomey LT: Clinical
Anatomy of the Lumbar Spine. New York, Churchill Livingston,
1987.
- 5.Nachemson AL: Newest knowledge
of low back pain: a critical outlook. Clin Orthop, 279:8-20,
1992.
- 6.Butler D, Trafimow JH, Andersson
GBJ, et al: Discs degenerate before facets. Spine, 15:111, 1990.
- 7.Lorenz M, Patwardhan A, Vanderby
R: Load-bearing characteristics of lumbar facets in normal and
surgically altered spinal segments. Spine, 8:122-130, 1983.
- 8.Dunlop RB, Adams MA, Hutton
WC: Disc space narrowing and the lumbar facet joints. J Bone
Joint Surg, 66B:706-710, 1984.
- Warren Hammer, M.S., D.C., DABCO
Norwalk, Connecticut
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