Posterior Lumbar Interbody
fusion (PLIF) in Lumbar Segmental
Instability - Current Concepts
Dr. P. Gopinath
Asst Professor in Orthopaedics
Medical College Calicut
E-Mail: drpgopinath@yahoo.com
Addresses for Correspondence
Dr. P. Gopinath
Asst Professor in Orthopaedics
Medical College Calicut,
Kerala, India.
Phone: +91 495 2390014
E-Mail: drpgopinath@yahoo.com
JJ.Orthopaedics 2005;2(4)e1
Introduction:
Since Cloward’s initial description of posterior lumbar
interbody fusion (PLIF) there have been numerous adaptations
and innovations which ahs really improved the out come.
Posterolateral fusion involving instrumentation-assisted
segmental fixation represents a valid procedure in the treatment
of lumbar instability. In cases of anterior column failure, such
as in isthmic spondylolisthesis, supplemental posterior lumbar
interbody fusion (PLIF) may improve the fusion rate and
endurance of the construct.
The
primary concern of LSI is radicular pain and pain due to
instability. The intervertebral disc is the most stabilizing
structure of the spine. The reduction in the disc height results
in narrowing of the size of the intervetebral foramen and
results in root compression.. This can be addressed to a certain
extent by foraminotomy but total correction of the fundamental
pathologic processes is possible only by maintaining the disc
height. This can be easily achieved by PLIF. The purpose of this
review article is understand the current concept regarding the
out come of PLIF in Lumbar segmental instability with the review
of Author’s own experience
Review:
La
Rosa G etal 1 inferred that an interbody fusion confers
superior mechanical strength to the spinal construct; when
posterolateral fusion is the sole intervention, progressive loss
of the extreme correction can be expected and at 2-year
follow-up examination, the correction of subluxation, disc
height, and foraminal area were maintained in the group in which
a PLIF procedure was performed, but not in the posterolateral
fusion-only group (p < 0.05.
Diedrich O etal 2 concluded from their study that normal
sagittal alignment after single-level lumbar fusion can be
achieved with rectangular and 4 degrees -wedged cages. Although
results after utilization of 4 degrees -wedged cages do not
significantly differ, these implants offer the surgeon one more
sizing variation with which physiological lumbar lordosis may be
attained. The combination of intersomatic implants with dorsal
instrumentation achieves a more precise realignment and has a
lower rate of cage-associated complications. It therefore seems
prudent that an interbody fusion(PLIF) for the surgical
management of lumbar segmental instability should be combined
with pedicular instrumentation.
Oda I
etal 3 were of the view that for spinal instability with
preserved anterior load sharing, pedicle screw fixation alone is
biomechanically adequate, and interbody cages should not be used
because they further increase segmental motion at the adjacent
segment. However, Pedicular screw alone provides insufficient
stability and high implant strain in case of damaged anterior
column. In such cases, additional interbody cages (PLIF)
significantly increase construct stiffness and decrease hardware
strain. However, they increase ROM at the adjacent segment as
well.
Wong
HK etal 4 concluded that Paired cylindrical cage installation in
the majority of patients is likely to require near-total or
total facetectomy, with implications for potential segmental
instability. Among the three lumbar segments studied, L5/S1 had
the highest proportion of segments that could accommodate paired
cages and at the same time restore intervertebral height.
Tsantrizos A etal 5 were of the opinion that The biomechanical
data did not suggest any implant construct to behave superiorly
either as a stand-alone or with supplemental posterior fixation.
The PLIF Allograph Spacer is biomechanically equivalent to
titanium cages but is devoid of the deficiencies associated with
other cage technologies. Therefore, the PLIF Allograft Spacer is
a valid alternative to conventional cages.
Enker
P et al 6 made the final conclusion that Persistent
pseudarthrosis rates and instrumentation failures have prompted
circumferential fusion techniques. Posterior lumbar interbody
fusion (PLIF) and segmental pedicle-based plate fixation
overcome earlier problems with PLIF by allowing for wide
decompression and increased exposure for disk space preparation,
minimizing neural injury. Pedicle fixation restores segmental
stability and minimizes graft retropulsion. Restoration of
anterior column support prolongs instrumentation life, and
increases fusion rates irrespective of the number of levels
fused. Disk space distraction, with the use of instrumentation
as a working tool, permits safer decompression of the
intraforaminal zone, a common area of stenosis, and single or
multilevel deformity correction to restore coronal, axial, and
sagittal alignment and spinal balance. Even though the surgical
technique is demanding, fusion rates up to 96% and clinical
success up to 86% are achieved.
Ohman
MA.7 Concluded that Posterior lumbar interbody fusion (PLIF)
incorporates variable screw placement and slotted plates with
transpedicular screws to correct spondylolisthesis, a
subluxation or displacement of the vertebrae. The indications
for PLIF include degenerative disc disease, recurrent disc
herniation, spinal stenosis including the central and lateral
foraminal varieties, various forms of instability associated
with these disorders, and cases of asymptomatic spondylolysis
with or without spondylolisthesis. 3. Complications include
infection, fracture of the pedicle, nerve root impingement
associated with the bone graft, and screw breakage. In cases
where infection does occur, the hardware must be removed.
The
authors own experience 8,9,10,11 is that maintaining the disc
height and achieving fusion between the two vertebral bodies by
PLIF has really improved the out come for the patients with
lumbar segmental instability.
Conclusion:
The biomechanical function
of an interbody fusion which supports the anterior column
provide adequate foraminal distraction and confer immediate
motion segment stability. This can be achieved only by a
fusion between the two vertebral bodies; and never by
posterolateral fusion alone. Interbody fusion can easily
be achieved by PLIF. Majority of the current articles and
authors on experience suggests that the clinical outcome of a
patient with lumbar segmental instability is definitely better,
provided PLIF is combined with posterolateral fusion and
instrumentation.
References:
1) La Rosa G, Conti A, Cacciola F, Cardali
S, La Torre D, Gambadauro NM, Tomasello F.Pedicle screw fixation
for isthmic spondylolisthesis: does posterior lumbar interbody
fusion improve outcome over posterolateral fusion? J Neurosurg.
2003 Sep;99(2 Suppl):143-50
2) Diedrich O, Luring C, Pennekamp PH, Perlick L, Wallny T,
Kraft CN Effect of posterior lumbar interbody fusion on the
lumbar sagittal spinal profile Z Orthop Ihre Grenzgeb. 2003
Jul-Aug;141(4):425-32
3) Oda I, Abumi K, Yu BS, Sudo H, Minami A. Types of spinal
instability that require interbody support in posterior lumbar
reconstruction: an in vitro biomechanical investigation. Spine.
2003 Jul 15;28(14):1573-80
4) Wong HK, Goh JC, Goh PS Paired cylindrical interbody cage fit
and facetectomy in posterior lumbar interbody fusion in an Asian
population. Spine. 2001 Mar 1;26(5):572-7
5) Tsantrizos A, Baramki HG, Zeidman S, Steffen T Segmental
stability and compressive strength of posterior lumbar interbody
fusion implants. Spine. 2000 Aug 1;25(15):1899-907.
6).Enker P, Steffee AD. Interbody fusion and instrumentation.
Clin Orthop Relat Res. 1994 Mar;(300):90-101
7) Ohman MAVariable segmental plating for the treatment of
spinal instability. Todays OR Nurse. 1992 Jun;14(6):21-8
8) Dr P gopinathan etal Lumbar segmental instability treated by
expandable cage J.Orthopaedics2004; 1(3)e4
9) Dr P Gopinathan etal Jacking up the spine –a better way of
treating lumbar segmental instability J.orthopaedics 2005;
2(1)e4
10) Dr P Gopinathan Lumbar segmental instability –current
concepts J.orthopaedics 2005; 2(1)e2
11) Dr P Gopinathan
etal lumbar segmental instability –a usually neglected reason
for chronic low back pain JCOA Vol3;No.2 ,21-27.
|