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Posterior Lumbar Interbody fusion (PLIF) in Lumbar Segmental Instability - Current Concepts

Dr. P. Gopinath
Asst Professor in Orthopaedics
Medical College Calicut

Addresses for Correspondence

Dr. P. Gopinath
Asst Professor in Orthopaedics
Medical College Calicut,
Kerala, India.
Phone: +91 495 2390014

JJ.Orthopaedics 2005;2(4)e1



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


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.



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.


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.



 This is a peer reviewed paper 

Please cite as :
P Gopinath: R
J.Orthopaedics 2005;2(4)e1






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