Decompressing and Fixing
Symptomatic High Grade
Dysplastic spondylolisthesis with
S1 pedicular screws crossing into
the inferior portion of L5
Case report.
Khalil I Issa M.D
Spine-Ortho. Nablus-Palestine
UWO-London-ON-Canada
T.Carey FRCS(C), C.Bailey
FRCS(C)
Introduction
• Spondylolisthesis is a radiographic/anatomic
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description which describes the anterolisthesis
( slip ) of a vertebra on the one immediately
caudal (inferior) to it.
The degree of anterolisthesis can be defined by
grade ranging from 1 to 5 with each additional
grade representing an additional 25% of the
distance from normal alignment to the stage of
spondyloptosis (grade 5 or complete slip).
Introduction
• Spondylolisthesis is usually classified by its
etiology.
• The most common classification is that by
Wiltse: Dysplastic, Isthmic (Spondylolysis,
lytic defect of the pars), Degenerative,
Traumatic, Pathologic, and Post-Surgical.
Discussion
• Dysplastic Spondylolisthesis is due to
congenital dysplastic change of the facet
producing the anterolisthesis.
• This usually occurs at L5-S1.
• The facet dysplasia can occur in the axial
or sagital plane, or can be due to an
elongation of the facets (Wiltse sub
classification).
Discussion
• The L5-S1 facet joint is oblique to the sagital
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and axial plane. The facets of the upper lumbar
spine most closely parallel the sagital plane. As
we descend caudally down the lumbar spine the
facets close to the sagital plane.
Normally, the S1 superior facet is approximately
45 degrees to the sagital plane. The S1 facet is
also oblique to the coronal and axial plane.
Therefore, dysplasia in the sagital or axial plane
implies the S1 facet is more parallel to the
sagital or axial plane respectively, allowing the
L5 inferior facet to “slide” anterior because the
S1 facet is no longer acting like a buttress.
Discussion
• Of all the spondylolisthesis types, congenital is most
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likely to produce neurological deficit by virtue of the
anterolisthesis alone.
This is because the grade of the listhesis can often
progresses greater than two and the posterior ring of L5
remains attached to its anteriorly displaced body.
The canal becomes narrowed between the posterior,
superior corner of S1 and the anteriorly displaced L5
posterior elements resulting in subacute or acute cauda
equina syndrome.
Discussion
• Congenital spondylolisthesis is relatively rare.
• It typically presents in children, adolescents, or
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young adults.
It more commonly presents with neurological
symptoms or leg pain as opposed to back pain.
May require urgent treatment if it presents as
cauda equina syndrome.
Some sort of decompression of the L5 lamina is
required in association with a fusion, possible
instrumentation procedure.
Case Presented as:
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11-year-old girl
A lot of growth over the last year
Tightness in her lower extremities.
Toe walking, particularly on the left
Underwent some stretching and massage-type
exercises in an effort to address this.
Her symptoms didn’t resolve.
Referred on for assessment.
Presentation
• She has been continuing to be active in sports
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including skating and hockey with discomfort.
Clinical examination showed a very dramatic
picture with a standing position with flexion at
the knee and the hip on the left side.
Unable to fully straighten her left leg without
discomfort.
Presentation
• She has an obvious step-off at the lumbosacral
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region with a flattened appearance to her
buttocks.
Significant tightness in her lower extremities.
Straight leg raising on the left side was about 5
or 10 degrees and on the right side about 40
degrees with crossover pain onto her left leg
X-Ray
• Full length as well as focused spine views.
• Confirmed the clinical suspicion of a
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spondylolisthesis.
She had a dysplastic spondylolisthesis with a
significant forward displacement of at least
grade 3.
She had the changes associated with a
dysplastic spondylolisthesis with a dome shaped
top of S1 and a trapezoidal L5.
She had a significant slip angle of 24 degrees.
No other abnormalities are detected.
MRI
• MRI showed an extremely tight stenosis.
Assessment
• This young lady has a high-grade
spondylolisthesis of the dysplastic variety.
• She is getting compression of the nerve
root at this area that accounts for her
lower extremity symptoms.
• She didn’t seem to have a frank
radiculopathy at the moment but thought
that it is certainly headed that way.
Assessment
• She denied any bowel or bladder issues.
• Assessed to need a fairly urgent
intervention for this.
• Requiring a posterior decompression
followed by an in situ fusion likely from L4
to S1.
• The necessity for careful monitoring of
cauda equina syndrome.
Operative Technique
Decompression
• Jackson frame on the OSI table, prone.
• We exposed from L4 to S1 there appeared
to be a significant deformity with a
marked forward displacement of L5/S1.
• laminectomy of L5 and of L4 for
decompression,the neural elements
identified and followed out.
• Significant tightness of both the L5 and S1
roots was seen.
Operative Technique
Decompression
• It was felt that it would be necessary to do an
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anterior decompression and therefore, by careful
retraction of the thecal sac, we were able to do
a removal of the posterior aspect of the sacral
dome which resulted in a decreased pressure
over the thecal sac.
It was felt that a reduction of this lip would be
ill-advised due to the moderate tightness noted
at the L5 root.
Operative Technique
Fixation
• We used 5.5mm polyaxial screws and we ensured
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pedicle screws in L4 pedicles bilaterally.
We then placed 6.5 mm screws into S1 pedicle. Image
intensification was used to help with the placement of
the screws and we were able to place the S1 screws
through the superior endplate of S1 across the 5-1 disc
space into the inferior portion of the body of L5.
Then rods were contoured to appropriately fit between
the screws and they were locked into place.
Allograft bone inserted.
She had neuromonitoring performed throughout the case
and this was maintained within normal ranges at all
times.
Post Operative Course
• She did well postoperatively.
• She was held over night in ICU and did quite
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well.
She was discharged to the floor the following
day and gradually mobilized. She was seen by
Physiotherapy and did well with mobilization.
She was discharged home on 4 days post
operatively.
Post Operative
2 weeks
• Improving from a neurological point of view, and
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has less abnormal gait according
She still had some tightness
Physiotherapy to work on her hamstrings and
heel cords.
TLSO with a hip extension to support her
surgical site in an effort to ensure she does not
get in to a pseudoarthrosis type situation.
Post Operative
2 Months
• Her incision is well healed.
• Overall she is quite comfortable.
• She has been working on trying to regain
range of motion as she had quite tight
hamstrings and heel cords.
• 5 degrees above dorsiflexion on her right
heel cord and about 5 below on her left
side.
Post Operative
2 Months
• Her straight leg raising is about 50 to 60
degrees on the right and about 45 to 50
on the left, and she has popliteal angles
about -45.
• On and to continue TLSO to keep her
restricted in her activities.
• X-rays were obtained today and these
show maintenance of the instrumentation
with no interval changes since her
postoperative films.
Post Operative
4 Months
• Doing quite well ,continued to attend
physiotherapy once every two weeks but
does physiotherapy approximately three
times a day at home. She has minimal to
no discomfort as well.
• TLSO full time as well.
• Able to dorsiflex to about 5-10 degrees
bilaterally. Her straight leg raise has
improved from previous and now is up to
about 70 degrees bilaterally.
Post Operative
4 Months
• X-rays today as though her lumbar fusion looked
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good, however it is always difficult 100% to
accurately find this via x-ray.
Overall she was doing quite well.
Allowed to get back to some activity as
tolerated.
Allowed to ride a bike, skip and such.
Allowed to start to discontinue the use of her
brace.
Results
• It secures fixation when combining L5 to
S1 keeping L5 in the construct
• It gives the ability to skip the so much
technically difficult L5 pedicular screws
• It augments graft healing
• It is safe and stable
Thank You