A retrospective study.
An en bloc partial laminectomy and posterior lumbar interbody fusion (PLIF) in spinal stenosis patients with severe foraminal narrowing has a shorter operation time, less neural manipulation and allows indirect decompression by restoring the interforaminal height compared to other procedures. This study investigated the efficacy of the procedure.
PLIF is one of the most popular surgery for degenerative spine such as foraminal spinal stenosis, instability spondylolisthesis and discogenic pain. Various techniques for PLIF have their own advantages and disadvantages. But in some severe cases, we need an efficient method of PLIF for decompression and fusion.
This study examined 61 patients, who had 85 levels treated with PLIF using an en bloc partial laminectomy and facetectomy, and could be followed up for more than 2 years. The mean age of the patients and mean follow up period was 66 years and 39 months, respectively. The clinical results were evaluated using the MacNab's criteria, Visual Analogue Scale (VAS) score, and Korea Version Oswestry Disability Index (KODI). The union of the intervertebral space was evaluated using Lenke's criteria. The intervertebral angle and height of the posterior intervertebral disc were also measured.
Excellent and good results were obtained in 54 cases (89%) according to MacNab's criteria. The VAS and KODI scores were 8.1 and 34.6, preoperatively, and 3.4, and 14.1, postoperatively. Bone union was A and B grades according to Lenke's criteria in 57 cases. The mean segmental angle and mean height of the posterior disc were respectively, 7.4° and 6.5 mm preoperatively, 9.1° and 10.6 mm postoperatively, and 8.0° and 9.7 mm in the last follow-up. There were 5 cases of postoperative infection, 4 cases of junctional problems and 1 case of screw malposition.
En bloc partial laminectomy and PLIF is an effective method for treating severe spinal stenosis with foraminal narrowing.
Decompression is a standard treatment regimen for the surgical treatment of lumbar spinal stenosis, and fusion is required in many cases after extensive decompression
Sixty one cases (87 segments), who underwent posterior lumbar interbody fusion using en bloc partial laminectomy between May of 2004 and February of 2007, and could be followed up for more than 2 years, were enrolled in this study. There were 24 men and 37 women. Patients with lumbar spinal stenosis or pseudospondylolithesis, who concurrently had a foraminal stenosis were indicated. There were 35 cases of 1 segment and 26 cases of 2 segments. Of these, 36 segments also had pseudospondylolithesis. Surgery was performed by the author in a single-institution setting. The mean age of the patients was 66 years (range, 45 to 82 years) and the mean follow-up period was 39 months (range, 24 to 57 months). In this series, the surgical indications included the following:
1) Extensive decompression was required due to the presence of severe foraminal stenosis. 2) There was instability or deformity due to foraminal stenosis and a chief complaint of discogenic back pain. 3) Degenerative spondylolisthesis with a current foraminal stenosis.
The conventional paraspinal posterior approach was used. But we did not need to exposure whole transverse process. In regard to an en bloc partial laminectomy, the inferior 1/2 of lamina and inferior 1/2 of the spinous process were resected using a power saw. 1/4 inch osteotome was then used to complete the osteotomy by tap and twisting motion. Ligamentum flavum was detached from the lamina using a curette. The posterior facet capsule was removed. The resected lamina containing the inferior articular process was removed en bloc from the underlying dura (
For a clinical evaluation, the clinical records, operation record and outpatient clinic record at the final follow-up were examined, and a telephone interview was performed. The Macnab classification system (
Statistical analysis was performed using SPSS ver. 12.5 (SPSS Inc., Chicago, IL, USA). The preoperative and postoperative findings were compared based on the clinical and radiological outcomes. A paired t-test was used to compare the VAS, KODI, segmental angle and posterior disc height between the two groups. A p-value<0.05 was considered significant.
Fifty four out of the 61 cases (89%) achieved more than good according to the Macnab criteria. Four (6%) and 3 (5%) cases had fair and poor clinical outcomes, respectively (
According to Lenke's criteria, 31, 26, and 4 cases were graded as Grade A, B, and other Grades, respectively. There were 2 cases of non-union due to postoperative infections. One non-union was to the result of a postoperative infection and was treated by removing the pedicle screw and the cage, followed by an autogenous bone graft. The other nonunion was managed by removing the cage and autologous bone graft. There was 1 case of non-infectious non-union, in whom the symptoms were improved by posterolateral fusion. The symptoms in the remaining case of adjacent problems were improved by conservative treatment. The mean segmental angle was increased from 7.4° (range, 3.2° to 12°) preoperatively to 9.1° (range, 7.2° to 14.1°) postoperatively (p=0.024). At a final follow-up, the mean segmental angle was 8.0° (range, 6.3° to 12.8°). The mean posterior disc height increased from 6.5 mm (range, 1.5 to 13.4 mm) preoperatively to 10.6 mm (range, 8.7 to 13.5 mm) postoperatively (p=0.023). The mean posterior height at the final follow-up was 9.7 mm (range, 5 to 12.7 mm) (
There were 5 cases of postoperative deep infection, 1 noninfective pseudoarthrosis, 4 adjacent problems, 1 screw malposition, 1 deep vein thrombosis, 1 cauda equine syndrome, and 4 dura tears.
An en bloc partial laminectomy and posterior lumbar interbody fusion yielded satisfactory outcomes in 54 of the 61 cases. Of the seven cases with fair or poor treatment outcomes, two cases had a non-spinal causative factor. This procedure could be extended multilevels, but our cases here were operated at 1 or 2 segments.
A different surgical approach is needed for the surgical treatment of spinal stenosis depending on the severity of the stenosis and the presence of instability. A simple partial laminectomy or partial facetectomy can improve the symptoms. However, in many cases in whom the stenosis was extensive or extended to the intervertebral foramen or its lateral side, a complete decompression cannot be obtained without sacrificing of the facet. Furthermore, bony fusion would yield a better treatment outcome in cases with concurrent instability, or potential discogenic back pain
There is some controversy regarding fusion after decompression. It was reported that bone fusion after a laminectomy produced good treatment outcomes
In cases of degenerative spondylolisthesis, only a laminectomy has been performed. Since the 1980s, fusion has been reported to gradually produce good treatment outcomes. After a simple decompression, bone ingrowth occurs in the resected lamina. Of these, many parts have been reported to show a recurrence of symptoms
An en bloc partial laminectomy and posterior lumbar interbody fusion have the following advantages:
1) The decompression time can be shortened. 2) During the decompression, neural manipulation can be reduced. 3) A posterior lumbar interbody fusion can be performed under good surgical vision with less neural manipulation. 4) A graft bone loss can be minimized.
At the preoperative planning stage, we could expect the parts of the lamina and posterior facet that should be resected if a wide decompression was necessary. Therefore, the surgical time can be reduced by en bloc partial laminectomy of this portion. During the decompression procedure, the unnecessary manipulation of the neural tissue was reduced. After inserting a cage in the intervertebral body, attempts were made to indirectly decompress the intervertebral foramen. There might be an advantage of posterior lumbar interbody fusion where the deformity can also be corrected. It can be confirmed whether the nerve root can be decompressed if the disc can be exposed sufficiently to the extralateral side. Hemostasis was achieved after a wider surgical vision. Without an excessive traction of the dura, a cage can be inserted for posterior lumbar interbody fusion. In determining the scope of decompression, some areas for which en bloc laminectomy is considered to be excessive can be included. However, in the current cases, partial conservation was not considered to be helpful for preventing the instability. There were advantages due to the acquisition of a wider surgical vision, such as the complete achievement of decompression, accurate bleeding control, less neural manipulation for the insertion of a cage and a prompt surgical procedure. The lamina that was removed en bloc was used as graft bone without bone loss in the cage. The allogeneic bone graft was performed using an additional intervertebral graft bone. A cage was lifted up in a 90° rotation and had a lordotic angle of 4°. There are some cases in whom it was effective for partially restoring lordosis. In some cases, restoration of lordosis was not effective due to some factors such as location of the cage, shape of endplate and osteoporosis. The mean level of recovery of the posterior disc height, which is considered to be one of the indicators for the decompression of intervertebral foramen, was approximately 4 mm. The level of recovery was well maintained at the follow-up study. Both clinically and radiologically, satisfactory outcomes were obtained using an en bloc partial laminectomy and posterior lumbar interbody fusion. It is believed that the current procedure will be very useful for suitable patients.
With regard to complications, there were five cases of infection, which is a relatively high incidence. However, the occurrence of infection was crowded at a certain period. In three cases, the symptoms were improved using IV antibiotics therapy. In two cases, additional surgery was required, which included the removal of the internal device or curettage. An adjacent problem (the degenerative changes of adjacent segments) was encountered in four cases. However, the corresponding cases were followed up using the conservative treatment due to the unclear presence of back or lower leg radiating pain with symptomatic improvements in 3 cases. One case of cauda equine syndrome occurred due to compression arising from a postoperative extradural hematoma. The hematoma was removed the next day after surgery. Two years after surgery, there were no problems with ambulation but the patient presented with bladder dysfunction. There were four cases of mild dura tear all of them were identified at operative field and managed with watertight sutures and fibrin glue without any continual CSF leakage.
This study had some limitations. No groups could be compared due to the lack of a control group, and the follow-up period was relatively short. According to Postacchini et al.
Posterior lumbar interbody fusion using an en bloc partial laminectomy is an effective surgery for patients with concomitant degenerative spinal stenosis and foraminal spinal stenosis where wide decompression and fusion is needed. However, long-term follow-up controlled trials on a larger scale using conventional methods and minimal invasive spinal surgery will be needed to confirm the efficacy of posterior lumbar interbody fusion using an en bloc partial laminectomy.
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Macnab classification
Fair & Poor result cases after en bloc laminectomy & posterior lumbar interbody fusion (PLIF)
Posterior disc height was designated by one number for 1 level case, and 2 numbers for 2 level cases.
Clinical and radiological results