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MANAGEMENT
Treating Ankylosing Spondylitis is a delicate task
that can be frustrating to the sufferer and the physician. Lifestyle
changes at times are required and ill habits such as smoking,
which is a detriment to individuals with AS, (2)
need to be eliminated. Options do exist to manage the horrific
manifestations of AS which need to be addressed and sought to
benefit the patient's quality of life and provide beneficial
long–term results.
Medication
Presently, there is no cure for
AS. However, the earlier AS is diagnosed the more optimum results
will be obtained from medicinal therapy. Conservative treatment
is carried out by the use of nonsteroidal anti–inflammatory
drugs (NSAIDs). NSAIDs help reduce pain, stiffness, and discomfort
by reducing the inflammatory activity. A large array of NSAIDs
are available, but preference and outcome varies between individuals.
Although Indomethacin, (7)
Naproxen, (45<)
and Phenylbutazone (7)
may be preferred among AS sufferers, Sulfasalazine, (13, 17) Diclofenac,
Fenoprofen calcium, and Salicylates have also shown efficacy
in relieving symptoms of AS. It should be noted that Salicylates
and aspirin are usually initially sought to relieve symptoms
of AS, but sufferers tend to depart from this medication and
seek other more potent routes as mentioned above. (7, 18) Furthermore,
a majority of NSAIDs have a tendency to cause gastrointestinal
bleeding, ulcers, and other adverse reactions; whereas, new Cox
2 inhibitors do not.
Although the entire purpose of
medication to treat AS is to reduce stiffness and pain in sufferers,
optimal improvement can be grasped with daily exercise or physical
therapy techniques. Exercise coupled with medication could lead
to beneficial results because inflammation is reduced and the
body is not exposed to long periods of rest allowing fusion to
fix the spine in a maladaptive position. Increasing the body's
range of motion always is beneficial and could hinder or prevent
poor posture.
Indications for Surgery
The surgical route is sought
when excruciating pain overwhelms the patient, neurologic deterioration
develops, a decrease in horizontal gaze, medication is not helpful,
and when spinal deformity is excessive to the point that it inhibits
daily activity and increases the risk of trauma. Although, surgical
intervention to rectify deformity of the spine as a result of
AS is a potentially harmful and delicate procedure, it could
provide a beneficial outcome for the patient by decreasing their
pain, increase their function and mobility, and soften physical
embarrassment. Since the natural progression of the disease varies
between individuals, a suggested timeline for operative management
depends upon the severity of the spinal deformity and the distress
and obstruction of daily function.
Age, sex, occupation, location
of the pronounced deformity, deterioration of quality of life,
severity of spinal deformity, appropriateness of the operation,
and postoperative rehabilitation are all are factors that need
to be assessed for operative treatment. Spinal deformity can
be measured by the chin–brow technique. This method measures
the angle produced by a line drawn from the brow to the chin
intersecting the vertical axis. The physician should periodically
assess the chin–brow measurement to establish a baseline
and monitor progressive spinal changes. Obviously, the greater
the angle the more pronounced spinal deformity exists and indication
for operative intervention should be sought.
Treatment of Thoracolumbar
Deformity
Correction for a pronounced spinal
kyphotic deformity has been investigated since the 1940s. Operative
procedures of the spine to correct AS need to be conscious of
the vital structures that surround the spinal column, but primarily
the spinal cord and neural roots. Therefore, many seek to decrease
the pronounced spinal deformity of AS in the lumbar region primarily
at the end of the spinal cord to avoid compression and at L2/L3
or L3/L4 where the descending aorta bifurcates and is more manageable
decreasing the risk of rupture. Also, dealing with the thoracic
region could lead to less beneficial results because of its involvement
with the rib cage and attached costovertebral joints that may
be affected by operative measures, and the presumably narrow
spinal canal that could increase the risk of cord compression.
However, AS patients with flexed contracture of the hip joints
should first undergo a bilateral hip arthroplasty before seeking
spinal correction. Nevertheless, AS patients with pronounced
thoracolumbar deformity should seek correction in the lumbar
region (Fig. 3);
whereas, AS patients with increased thoracic kyphosis and an
intact lumbar lordosis should seek thoracic correction. Therefore,
particular attention needs to be given to the vertebral level
that will be responsible for the new shape of the spine.
Smith–Petersen, Larson,
& Aufranc Approach – Introduction of the Lumbar Osteotomy
Correction of spinal deformity
is primarily accompanied through lumbar osteotomy. As a result
of this procedure, relordosation is accomplished and kyphotic
deformity is decreased throughout the spine. Although, there
have been numerous accounts detailing operative techniques to
correct kyphosis, the use of internal instrumentation, depth
of osteotomy and approach, and use of bone graft are evolving.
Nevertheless, vertebral osteotomy to correct spinal deformity
in AS sufferers was first introduced by Smith–Petersen,
Larson, and Aufranc in 1945. (38)
The technique by Smith–Petersen
et al provided the foundation for possible routes in correcting
pronounced kyphosis in AS. Smith–Petersen et al presented
five cases of lumbar monosegmental or multisegmental posterior
osteotomy. Osteotomy location was determined by the less ossified
segment (s) on radiographic evaluation that would render greater
manipulation ease. This procedure begins with the patient in
the prone position under general anesthesia. An incision is made
in the midline including at least three vertebral levels of interest
at the lumbar region. The spinous processes involved (L1–L2
and L3) are excised as well as ones directly above and below.
Retraction of muscle attachments from the spinous processes and
laminae is carried out. The ligamentum flavum is removed and
by use of an osteotome a V–shaped wedge osteotomy at a 45
degree angle from the frontal plane is accomplished through the
superior articular processes of the inferior vertebra and the
inferior articular processes of the superior vertebra (Fig.
4 A,B). (38)
Bone graft from the excised spinous processes is inserted between
the lamina for support and as an anchor to achieve desired lordosis.
Closing the osteotomy is achieved by manual means or by raising
the head and foot of the operating table to meet the desired
spinal curvature (Fig.
5). The patient is then closed and a plaster shell is applied
for four to six weeks. Afterwards, the patient is instructed
to remain in a plaster jacket for one year. All five patients,
in the original report, tolerated the procedure fairly well and
were ambulatory and reported little to no pain. It should be
noted that in the report by Smith–Petersen et al, a sixth
case was also mentioned, but it involved an individual who underwent
lumbar and thoracic osteotomies whose outcome objectively did
not improve.
Introduction of the Two Staged
Approach –Anterior & Posterior
One of the main concerns of operative
procedures to correct spinal deformity of AS is to establish
a desired curvature and allow it to remain so postoperatively.
However, if the desired spinal correction was not obtained other
avenues were sought. La Chapelle in 1946 (26)
reported on posterior vertebral osteotomy with anterior intervertebral
disc bone graft insertion. La Chapelle recommended a similar
procedure as Smith–Petersen et al, but removed laminae with
local anesthesia and included a second stage two to three weeks
after the first operative osteotomy with general anesthesia.
Although laminectomies in AS patients, whose lumbar muscles are
weakened or atrophied, could pose threat of spondylolisthesis,
LaChapelle believed that an intact ossified posterior longitudinal
ligament would prevent such a risk. In the second stage, under
general anesthesia, the patient is placed in a left lateral decubitas
position and a transverse abdominal incision is carried out at
the level of the umbilicus. After retraction of the peritoneum
and obvious structures the lumbar spine is viewed and displacement
of the aorta and inferior vena cava is accomplished. The intervertebral
disc is excised and packed with autologous bone graft in a desired
amount to obtain curvature while not excising the posterior longitudinal
ligament. Afterwards, the patient is stabilized in a plaster
spica for three months and a plaster jacket for six months. Ambulation
is slowly accomplished beginning after four weeks.
In 1959, Herbert (22)
performed a similar approach as La Chapelle, but resected the
neural arches in a T–shaped posterior osteotomy to avoid
spinal cord compression in the event subluxation occurred. Herbert
chose the location of the posterior osteotomy by determining
the least ossified intervertebral disc. Herbert also performed
a second stage osteotomy as La Chapelle, but sectioned the corresponding
intervertebral disc to promote collapse and to achieve deformity
correction.
Internal Metallic Instrumentation
Internal stabilization to correct
for fixed lumbar deformity in AS was first reported by Briggs
et al in 1947. (6)
Briggs et al postulated a monosegmental posterior closed wedge
osteotomy, with essential disruption of the anterior longitudinal
ligament and bilateral intervertebral foraminotomy to correct
for lumbar kyphosis. The osteotomy Briggs et al implemented consisted
of a wedge removal of the adjacent spinous processes, superior
articular processes, and a portion of the pedicle. Location of
the osteotomy was determined by a radiographic evaluation of
the greater ossified anterior longitudinal ligament. Rupture
of the anterior longitudinal ligament intraoperatively by manual
pressure was shown to facilitate in reestablishing physiologically
correct lumbar lordosis. However, in the event the anterior longitudinal
ligament did not break, a curved Wilson plate was applied on
the right lateral surface of the involved spinous process. Furthermore,
a plate was also implemented in preventing vertebral spondylolisthesis
due to the instability a ruptured anterior longitudinal ligament
might impose on the vertebrae.
Further accounts of internal
metallic fixation were also reported by Lichtblau and Wilson
in 1956 (32)
and Law in 1959, 1962, and 1969. (28–30)
Law's reports of surgical correction of AS kyphotic deformity
were the largest of his time. In 1952, Law reported his experience
with monosegmental osteotomy at L2–L3 utilizing the Smith–Petersen
et al technique in (30)
patients. (28)
Law avoided rupture of the anterior longitudinal ligament and
implemented prolonged external plaster cast fixation to promote
bone consolidation. In the following years, 1959, (28) 1962, (29) and 1969,
(30)
Law reported the outcome of 100, 110, and 120 patients respectively.
However, since 1959 Law applied wire loops and metal plates around
the spinous process for increased internal stability and to decrease
postoperative external immobilization wear. Although Law presented
a large sample of kyphotic correction, his mass experience and
reports also noted a 10% risk of death associated with surgical
intervention.
Simmons in 1977 (37)
was the first to use Harrington compression system for correction
of AS thoracic deformity. Simmons presented a case of a 38–year–old
female with 116 degrees thoracic kyphosis at T2–T11 with
anterior spondylodiscitis at T8–T9. The patient presented
a sharp angular kyphosis with accompanying skin breakdown at
kyphotic proximity, restricted pulmonary capability, shortness
of breath, and a degree of subluxation at C1–C2. The patient
was first placed into a halo–femoral traction for three
weeks in which her thoracic kyphosis reduced to 68 degrees. Surgical
intervention was then performed via a transthoracic approach
and Harrington compression instrumentation was appropriately
applied which reduced her thoracic kyphosis to 50 degrees. At
2 ½ years status post, the patient managed to maintain
her newly constructed thoracic curve and presented no signs of
neurologic compromise.
Simmons, also reported his experience
with surgical intervention for lumbar AS deformity with posterior
wiring to maintain corrected spinal curvature. Simmons, utilizing
the Smith–Petersen et al technique, performed a monosegmental
posterior osteotomy with osteoclasis of the anterior longitudinal
ligament in 19 patients under local anesthesia and positioned
laterally. Simmons selected the site of the main deformity to
perform an osteotomy. His preference was reported as L3–L4,
but his results showed osteotomies at L2–L3 in eight patients,
L3–L4 in eight patients, and L4–L5 in three patients.
He used 20 gauge stainless steel wires to loop through holes
in adjacent spinous processes in relation to the osteotomy. His
procedure achieved a deformity correction of 30–60 degrees
and an average of 47 degrees. As a result of the operation, no
mortalities occurred as well as no signs of permanent neurologic
deficit.
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