3. Clinical Lumbar Instability
• Not any specific definition
• … the condition that the
patient feels that his back
is unstable
White A. & Panjabi M.
Clinical Biomechanics of the Spine 1980
5. Lumbar Instability
The main cause
of lumbar instability
in adults is the instability
of the spine that follows
the operative treatment
of lumbar stenosis
28. Pre-existing conditions associated with
increased operative risk or difficulties
I. Deformities e.g. scoliosis,
spondylolysis,
spondylisthesis
II. Infections or tumors
III. Previous discectomies
IV. Previous laminectomies
V. Previous lumbar fusions
VI. Previous operated spinal
deformities
VII. Pre existing instabilities
VIII.Inadequate investigation
• Clinical
• Radiological
33. Late post-operative causes of failure
(b. > 3mths)
• Implants failure
• Destabilization
– at the level(s) of the operation
– at the level above -//-
– at the level below -//-
• Pseudarthrosis
• Recurrence of stenosis
• Late infection
35. Intra-operative
• Removal of the
ligamentous and bony
structures destabilizes
the lumbar spine
• Instability discovered
intra-operatively extends
the operative time.
36. • In case of pre-existed
pathology e.g.
osteoporosis,
tumor,
infection
• The fixation of the
implants is not safe
• The dissemination
(malignant tumor)
is very likely
41. c. Pain
Post-operative failures due to:
–Buttered nerve roots
–Muscles destruction
–Implants failure
–Instability
cause
a. considerable
back and leg pain
b. disability
42. Neurologic compromise:
•Recurrence of stenosis
•Instability
– May lead to anterioposterior or lateral
subluxation – displacement.
The abnormal spatial relationship is
achieved at the cost of spaces
through which the nerve roots of
the cauda equina travel in their
course from the spinal cord
to and through the neural foramen:
injury to the nerve root(s)
may result.
50. Intra-operative:
• When the spinal
instability is recognized
intra-operatively
consideration should be
given to perform
spondylodesia
with or without
instrumentation
75. II. The frequency of
instability
complicating lumbar
laminectomy is higher
in patients with:
• pre-existing pars defect
(spondylolysis -
sthesis)
• Spondylolisthesis
• Congenital or
developmental lumbar
stenosis
76. III. Removal of the least
possible of the bone
(facets) and soft
tissues (ligaments &
facets capsule)
is essential in the
prevention of
instability following
lumbar laminectomy
77. IV. Instability complicating
lumbar laminectomy
can be avoided if the
surgeon proceeds in
spondylodesia of the
affected levels with or
without
instrumentation
in case that instability
is encountered
intra-operatively