The aim of this
study was to assess the clinical outcome of interlaminar
discectomy by fenestration technique. Since there is no
significant difference between standard extensive laminectomy or
limited fenestration and discectomy, it is preferable to opt for
limited laminotomy or fenestration because extensive laminectomy
may cause destabilization of spine later. We made a prospective
study of 32 consecutive patients who underwent limited lumbar
discectomy by fenestration technique in Victoria Hospital and
Bowring and Lady Curzon Hospital, Bangalore from Jan 2003 to
June 2005. The clinicoradiological parameters, appropriate
indications for surgery, state of intervertebral disc at the
time of surgery, and the post-op follow up were assessed.
We found that 20 patients had disc herniation at L4-L5 and 07
patients had disc prolapse at L5-S1 and remaining 5 patients had
two level disc prolapse at L4-L5 and L5-S1.The last group
underwent fenestration at two levels simultaneously. The results
were evaluated using the criteria similar to those of MacNab and
PROLO functional and Economic outcome criteria.The postoperative
results were good in 29 (90%) patients, fair in 2 (6.2%)
patients and poor in 1 (3.1%) case.
The results of this study show that enough space is available
in interlaminar area to perform fenestration and disc excision
without removing much of lamina. The results are comparable to
microdiscectomy in standard references.
In conclusion, interlaminar lumbar discectomy by fenestration
method without extensive laminectomy is effective and reliable
surgical technique for treating properly selected patients with
herniated lumbar disc at L4-L5 and L5-S1 levels.
Key words: Fenestration, Limited disc excision, Lumbar
Low back pain due to lumbar disc prolapse is the major cause
of morbidity throughout the world affecting mainly the young
adults. Lifetime incidence of low back pain is 50-70 % with
incidence of sciatica more than 40 %. However clinically
significant sciatica due to lumbar disc prolapse occurs in 4-6 %
of the population. The degeneration of the disc results from
many factors and can lead to prolapse into the intervertebral
foramen, particularly at L4-L5 & L5-S1 level. The L3-L4 & L2-L3
account for the majority of remaining herniations1, 2. Detailed
history, clinical examination supplemented by relevant
radiological investigations can differentiate herniated lumbar
disc prolapse from other causes of low back pain and sciatica.
The outcome of surgery depends on many factors, such as careful
selection of patients.
The success rate after lumbar discectomy reported in the
literature varies considerably from 46% to 90%1. In the past
various authors have attributed this variability to the surgical
technique. It is apparent, however, that a more common reason is
faulty patient selection criteria1.
The technique of lumbar discectomy has undergone significant
modifications. Originally, a wide laminectomy was performed in
an attempt to remove as much disc material as possible. This
more radical surgery is no longer common as because extensive
laminectomy may cause destabilization of spine later 1, 3. In
1982, Spengler described limited disc excision, only the
ligamentum flavum and if necessary small portion of lamina
inferiorly is removed to expose the prolapsed disc space and the
extruded disc were removed1. Machemson advocated removal of only
sequestrated and extruded loose disc fragments, with the minimal
removal of tissue fragments from the intervertibral space2, 5.
The advantage of limited lumbar disc excision by fenestration
technique is a decrease in the incidence of postoperative spinal
instability, decreased manipulation of the neural elements and
subsequent perineural fibrosis1, 3, 5. In addition limited disc
excision lessens the likelihood of penetration of the anterior
annulus with potential injury to the viscera. This study was
performed to assess the results of limited lumbar disc excision
through interlaminar fenestration in patients fulfilling
Materials & Methods
We made a prospective study of 25 consecutive patients who
underwent limited lumbar discectomy by fenestration technique in
Victoria Hospital and Bowring and Lady Curzon Hospital Bangalore
from Jan 2003 to June 2005. 18 patients were men and 14 patients
were women. The average age at surgery was 34 years (range, 22 -
48 years). Objective neurological deficits were observed in 14
patients (43.7%) with one patient with bowel and bladder
deficits (cauda equina syndrome). Method of collection of data
is by patient’s evaluation through proper history taking
regarding the low back pain as assessed by Back pain function
scale, 6 thorough clinical examination, The clinical diagnosis
was confirmed by CT scan or MRI. The criteria for selecting the
patients were disc prolapse with bowel & bladder symptoms (cauda
equina syndrome), with sensory or motor deficits, and with
severe sciatica (unilateral or bilateral sciatica), which
decreased by conservative measures (rest, anti-inflammatory
medication, physiotherapy or even epidural steroids) but
returned to the initial levels after a minimum of 6-8 weeks of
above-mentioned conservative measures. And a Wadell nonorganic
signs of less than 3 4.
Patients with disc prolapse other than L4-L5 and L5-S1,
spinal canal stenosis, far lateral foraminal stenosis, and
penetration of disc into the dura were excluded from the study1,
2, 5, 7. We obtained preoperative marker films in all cases to
identify the proper level. Surgery was performed with the
patient in knee chest position or prone position over bolsters.
General anaesthesia was employed in all cases. The skin and Para
spinal muscles were infiltered with 1 in 100000 diluted
adrenaline to decrease the bleeding. Spine was approached
through a two to three inch midline incision depending on the
We did a standard interlaminar fenestration by cutting
through ligamentum flavum and if necessary only inferior lamina
using Kerrison`s rongeurs. The sequestrated and extruded loose
disc fragments were removed, with the minimal removal of tissue
fragments from the intervertibral space. The exiting nerve roots
were cleared of compression in all cases. The residual
interlaminar defect was closed by free fat graft in few cases.
Post operatively patient is made to stand up and ambulate on
the next day and discharged within a week from the hospital.
Sutures were removed after two weeks. Back strengthening
exercises were advised from second week. Patient is advised to
return to original occupation after 6 weeks2.
20 patients (62.5%) had disc herniation at L4-L5 and 7
patients (21.8%) had disc prolapse at L5-S1 and remaining 5
patients (15.6%) had two level disc prolapse at L4-L5 and
L5-S1.18 patients were men and 14 patients were women. The
average age at surgery was 34 years (range, 22 - 48 years). All
7 patients with disc prolapse at L5-S1 were managed by
interlaminar fenestration. Of the 20 patients with disc prolapse
at L4-L5, 15 patients underwent only interlaminar fenestration
and remaining 5 needed small inferior laminotomy to access the
dura and disc. Patients who had disc prolapse at L4-L5 and L5-S1
levels underwent fenestration at two levels simultaneously. 10
patients (32%) had no Wadells nonorganic signs, 6 patients (10%)
had one sign, 15 patients (46.8%) had two signs and 1 patient
had 3 signs. Neurological deficits (either motor or sensory)
were observed in 15 patients (60%) with one patient with bowel
and bladder deficits (cauda equina syndrome). Of the 20 men 12
patients (40.6%) were active smokers. Co morbid conditions like
diabetes and hypertension were present in 15 patients (48%). The
average duration of hospital stay prior to surgery was 2 days.
The average operating time for fenestration surgery was 65 min;
with a range of 40-130 min. The average blood loss was 180ml.
Only 2 patients (all women) required blood transfusion. These
two patients had preoperative low hemoglobin levels. The average
postoperative hospital stay was 3 days with a range of 2 to 5
days. Among immediate complications 2 patients (6.2%) had
superficial infection, which required antibiotics for one week
and two dressings, and one had dural tear. 2 patients (6.2%) had
postoperative urinary retention which required catheterization
for 1 day and both of them were males. Fortunately none of the
complications permanently affected the outcome.
All patients were assessed after 3 weeks and at 6 weeks
postoperatively and there after once 3 months. The average
follow-up is 8 months, with a range of 6 weeks to 19 months.
Follow up of the patients was done on regular OPD basis with
history taking and assessing the back pain function scale,
clinical examination and relevant radiological investigations in
certain patients. The results were evaluated using Mac Nab`s
Mac Nab`s criteria1 of
- Excellent is dropped.
1. Resumed preoperative function
2. Occasional backache or leg pain.
3. No dependency inducing medication intake
4. Appropriate activity
5. No objective sign of nerve root irritation.
1. Intermittent episodes of mild radicular or low back pain.
2. No dependency inducing medication intake
3. Appropriate activity
4. No objective sign of nerve root irritation.
2. No productive occupation
3. Continuing or worsening symptoms
4. Abuse of drugs
5. Objective sign of nerve root irritation.
The results were classified as good in 29
(90%) patients, fair in 2 (6.2%) patients and poor in 1 (3.8%)
case. The patient poor recovery had Cauda Equina syndrome.. The
functional recovery of neurological deficits occurred 4-8 months
after the surgery.
A review of literature reveals success
rates for lumbar disc surgery ranging from 46-96%1. The outcome
of the lumbar discectomy depends more on the patient selection
than on the surgical technique. Good results were obtained in
90% of the cases in our series. The fair results were related to
subjective factors rather than to any objective impairment of
function of the musculoskeletal system. All the four patients who
had fair results had co morbid condition like diabetes mellitus
or hypertension. And all of them had Wadells nonorganic signs as
Spengler described the technique of limited
disc excsion through fenestration in 19821. The advantages of
this technique are decrease in the incidence of postoperative
spinal instability, decreased manipulation of the neural
elements and subsequent perineural fibrosis and less likelihood
of penetration of the anterior annulus with potential injury to
the viscera. In the present study, interlaminar discectomy was
adequate in 27 cases (84%). No laminotomy was required in these
patients. Remaining 5 patients (16%) required inferior
laminotomy. Most of these patients had disc prolapse at L4-L5 or
double level disc prolapses. And laminotomy was done mostly
during the early phases of learning curve. Thus interlaminar
fenestration without laminotomy gives adequate space for disc
excision at L4-L5 and L5-S1 levels in majority of patients. The
role of autogenous fat graft is still debated2, we have used in
few patients. No case of perineural fibrosis noted in our series
till the last follow up.
A few authors have reported higher rates of
success, a shorter hospital stay, and quicker return to work
after microdiscectomy, but that has not been established in
well-controlled studies3. In our series the operating time, in
patient stay and success rates were comparable to the results of
microdiscectomy reported in various studies. This might be due
to close similarity of the two techniques. However
microdiscectomy offers a better visual comfort and facilitates
The results of this study show that enough
space is available in interlaminar area to perform fenestration
and disc excision without removing much of lamina. The results
are comparable to microdiscectomy in standard references.
In conclusion, interlaminar lumbar
discectomy by fenestration method without extensive laminectomy
is effective and reliable surgical technique for treating
properly selected patients with herniated lumbar disc at L4-L5
and L5-S1 levels. The results are comparable to microdiscectomy,
and this may be due to close similarity of the two conditions.
Dan M. Spengler, M D, Results with limited disc excision: Spine
7:604- 607, 1982.
Michael H. Newman M D, out patient conventional laminotomy and
disc excision. Spine 1995 Vol 20, no 3, pp 353-355
Dietmar Stolke, MD, Wolf peter Sollman, Intra and postoperative
complications in lumbar disc surgery MD.Spine, Vol 14, Number 1,
Tania Larequi-Labuer, MD John-Paul Vader, MD, MPH. Appropriate
indications for surgery of lumbar disc hernia and spinal
stenosis. Spine vol, 22, nov-1997, page-203-209.
Manish Garg and Sudhip Kumar. Interlaminar discectomy and
selective foraminotomy in lumbar disc herniation. Journal of
orthopaedics 2001, 9 (2): 15-18.
Stafford et al, Back pain function scale, Appendix A. Spine, vol
25, Number 16, 2000.
Toshihico Maruta, MD, Sherwin Goldman, MD. Waddell’s nonorganic
signs and Minnesota Multiphasic Personality Inventory Profiles
in patients with chronic low back pain. Spine, Vol 22, Number 1,
Tycho Tullberg, MD, Johan Isacson, Does Microscopic Removal of
Lumbar Disc Herniation Lead To Better Results Than The Standard
Procedure, Spine, Vol 18, number 1, 1993.