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Abstract:
The objective of
this study is to discuss the procedure and the advantages of
this minimally invasive percutaneous technique for fixation of
spondylolisthesis.Literature is full of various fusion methods
for spondylolisthesis.We studied this minimal invasive method
9[n=9] patients were operated by minimal invasive
instrumentation for Spondylolisthesis from Jan 07 to July 08 at
Nizam’s Institute of Medical Sciences. 3[33.3%] of the nine
were male patients and 6 [66.6% were females]. Age range was
from 40 to 58 years. 1 patient [11.1%] had spondylolisthesis at
L3-4 level, 6 [66.6%] at L4-5 level and the 2 [22.2%] at L5- S1
level. 6 [66.6%] had Grade I listhesis and 3 [33.3%] had Grade
II listhesis. 4 patients [44.4%] had degenerative type of
Spondylolisthesis , 4 [44.4%] had lytic type and one [11.1%] had
post-operative discectomy status.Pain decreased in all the
patients [mean decrease in VAS score of 7.8].There was no
incidence of post-operative neurological deficits in any
patient. There was less amount of muscle dissection leading to
less operative blood loss and less post-operative pain and
discomfort to the patient. The average surgery to discharge time
period is 4 days. The average operating time is 4.5 hours. This
is a safe procedure and another lesser invasive tool in the
surgeon’s armamentarium for Grade I & II listhesis. It is
effective in producing pain relief as well as causing less
morbidity to the patient.
J.Orthopaedics 2009;6(1)e8
Keywords:
VAS score;degenerative spondylolisthesis; Isthmic spondylolisthesis ; [TLIF]
Introduction:
Spondylolisthesis
is a penalty for erect posture.Originol description was of
lytic listhesis, later degenerative was described. It
causes various degrees of morbidity and most commonly
occurs at the lumbosacral junction at L5/S1 level.
Aetiologically it has 5 types: congenital or dysplastic,
isthmic, degenerative, traumatic, and pathologic (Wiltse,
1976)11. Besides conservative treatment, in persons with
incapacitating symptoms surgery is indicated. The surgical aim
is to stabilize the segment and decompress the neural elements
if needed. Albee and Hibbs separately published their
initial work on spinal fusion. Their methods were applied
quickly to cases involving trauma, tumors, and, later,
scoliosis. In the latter half of the 20th century, spinal fusion
was used increasingly to treat degenerative disorders of the
spine, including degenerative spondylolisthesis and degenerative
scoliosis. Degenerative spondylolisthesis is observed more
frequently as the population ages. Up to 5.8% of men and 9.1% of
women have this type of spondylolisthesis.
Etiology:
The
etiology of spondylolisthesis is multifactorial.2,6,9 A congential
predisposition ,posture, gravity, rotational forces, and high
concentration of stress loading all play parts in its
development . The following aetiological types are adapted
from Wiltse et al (1961)11:The dysplastic ,Isthmic,degenerative,traumatic,pathological.
Meyerding
grading [1932] include: Grade 1 - Less than 25% of vertebral
diameter ,Grade II - 25-50% ,Grade III - 50-75% ,Grade IV -
75-100% and Grade V Spondyloptosis - Greater than 100%.
Indications for surgical intervention (fusion) include :
Neurological signs - Radiculopathy (unresponsive to conservative
measures), myelopathy, neurogenic claudication ,Type 1 and type
2 slips, with evidence of instability, progression of
spondylolisthesis, traumatic spondylolisthesis ,Iatrogenic
spondylolisthesis ,Type 1,2 (degenerative) spondylolisthesis
with gross instability and incapacitating pain1,postural
deformity and gait abnormality
Surgical Options:
The
goal of surgery is to decompress the neural elements and
immobilize the unstable segment or segments of the spinal
column. This is usually performed with elimination of motion
across the facet joint and the intervertebral disc through
arthrodesis. Fusion: Multiple methods exist to achieve
intersegmental fusion in the lumbosacral spine of which
widely used methods include:Posterolateral (intertransverses):
Most surgeons use the intertransverse or transverse
process/sacral ala arthrodesis with the use of iliac crest
autograft alone or in conjunction with allograft. This may be
performed over one or multiple levels with high success rates
(up to 90%) of fusion. Some surgeons prefer a 2-level fusion
(i.e., L4-S1) for treating high-grade (>50%)
spondylolisthesis . Segmental spinal instrumentation allows
rigid fixation of the fused segments and the possibility of
performing reduction of the segment with spondylolisthesis.
Lumbar interbody fusion: Biomechanically interbody fusion
increases the stability of the spinal segment by placing
structural bone graft in compression in the anterior and middle
columns and increases the overall surface area of the bony
fusion. It can be done with posterior (i.e, posterior lumbar
interbody fusion [PLIF]),transforaminal lumbar interbody
fusion[TLIF] or anterior (i.e, anterior lumbar interbody fusion
[ALIF]) approaches. TLIF is essentially an extended PLIF which
was developed in response to some technical problems in PLIF.The
main difference between two posterior fusion procedures is that
TLIF involves removal of an entire facet joint on one side,
whereas PLIF is usually done on both sides by removing only part
of fact joint. A growing number of surgeons use interbody grafts
to augment their posterolateral fusion techniques to
achieve higher rates (>95%) of arthrodesis. Cages have far
more better results in terms of disc height maintenance
and indirect neural decompression than bone grafts alone11 .It
should be noted that grade 2 or higher slips are predisposed to
higher rates of graft complications. Fixation Although the use
of spinal instrumentation in skeletally immature patients is
considered optional by some surgeons ,for some patients with
isthmic-type spondylolisthesis, most spinal surgeons believe
that rigid fixation is needed to achieve a solid fusion
reliably. For degenerative-type slips, fixation has been shown
to achieve higher rates of solid arthrodesis.
Materials
and Methods:
This
study involved (n=9).6 [66.6%] were females and 3 [33.3%] were
males. Patients Included were: Patients having
age of 40-58 years, symptomatic patient with disturbed
ADL,single level L3/4, L4/L5 or L5/S1 Grade I or grade II
spondylolisthesis. Patients with severe osteoporosis,recent
spondylodiscitis subchondral sclerosis,visual and cognitive
impairement were excluded. All the patients underwent
transforaminal discectomy after a muscle splitting approach and
unilateral partial facetectomy. Short segment posterior fixation
was done using using sextant instrumentation [medtronics,USA]
underc-arm control. In 55.5%(n=5 ) patients titanium cages were
used while in 44.4 %(n=4) patients PEEK Cage was used .The
mean follow-up period was 18 months.
In
the present study all patients were asked history and subjected
to thorough clinical examination. The preoperative VAS scores
were noted down.The preoperative dynamic x-rays were taken and
the intervertebral disc heights and slip grade (Meyerding
grade) were measured. Patient’s written and informed
consent was taken. All the investigations relevant from the
point of view of anaesthesia were done and the pre-anaesthetic
clearance was taken before surgical procedure. Operative
technique: After satisfactory induction of anaesthesia, the
patient was positioned prone on a four-poster frame and all
pressure points were well padded. A standard midline posterior
approach was used to expose the spine as per the level of
involvement. With a midline skin and paramedian
muscle splitting incision ,the hidden area of Mcnab was
resected which includes unilateral partial facetectomy and
hemi-hemilaminectomy Lateral margin of ligamentum flavum
was identified and partially resected.Nerve root of involved
level was identified and kept safe with gel foam pledgets. The
total discectomy and complete removal of cartilaginous
endplate was performed at the degenerated level.The level
involved was fixed with transpedicular
monoaxial or polyaxial screws using minimal invasive stab
incisions with percutaneous cannulated screw fixation followed
by insertion of precontoured rods over the screw slots using
sextant jig. After the reduction maneuver and distraction of
intervertebral space the interbody spacer was placed.Final
construct was tightened in compression to achieve lordosis. All
these steps were done using C-ARM.We did not perform any SSEP
during the procedure.Haemostasis was achieved and stab
wounds were closed in layers. Patient was subjected to X-ray
Lumbosacral spine[ AP & Lateral views] on first
postoperative day. After surgery patients were braced in LSO for
a period of 3 months for comfort.Patient was discharged on third
post operative day and advised to follow the OPD on tenth
day for removal of stitches and subsequently to every
three months for about 18 months. The total operative time
averaged 4.5 hours(Range 3-5hrs).The estimated blood loss was
100ml(Range 50-150 ml)
Results:
Among
nine (n=9) patients,66.6%(n=6) were females and 33.3%(n=3) were
males.11.1% (n=1) were having L3/L4 ,66.6%(n=6) were having
L4/L5 and 22.2%[n=2] were having L5/S1
spondylolisthesis. 66.6%(n=6) were of grade I and 33.3%(n=3)
were of grade II spondylolisthesis.6 patients [n=6] were of
degenerative spondylolisthesis,2 patients[ n=2] of lytic variety
and one patient [n=1]was of post-discectomy status.Reduction was
achieved in all the patients and well maintained
postoperatively.
There
was no incidence of post-operative neurodeficit.We observed less
amount of muscle dissection, less operative blood loss,less
postoperative pain and average hospitalization of 4 days.
There
was a significant decrease in pain with mean VAS score
improvement of 7.8, postoperatively at the end of follow up
period of 18 months1. There was no case of fresh neurodeficit,
implant loosening, loss of reduction, infection, subsidence or
pseudoarthrodesis during this whole period of follow up.
Advantages
of Procedure:
This
surgery eliminates need for a large midline incision and
significant muscle dissection. Paraspinal muscles are bluntly
split, rather than divided, leading to potentially shorter
periods of hospitalization and recovery.Both the pedicle screws
and pre-contoured rods are placed through stab incisions.An
ideal lateral to medial screw trajectory is used and as such
significant paraspinous muscle dissection is avoided.There is
least retraction of dural sac [not exposed] and nerve root.
Limitations:
L5/S1 level gives a harder time to the surgeon due to high
lumbosacral kyphus or high iliac crests.The procedure
has a steep learning curve
Conclusion :
It
is a safe procedure, less invasive in nature and effective in
producing pain relief1 besides causing less morbidity to the
patient.It provides anterior column support and posterior
tension band.It is a unilateral approach without need to expose
the dura.It provides the benefits of a 360੦ fusion without
performing an anterior approach. Patient rehabilitation is
faster.
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