technical aspects of percutaneous vertebroplasty & kyphoplasty
TRANSCRIPT
Technical Aspects of PercutaneousVP and KP procedures
The Neurosurgeon’s perspective
M o h a m e d M o h i E l d i nProfessor of Neurosurgery
Cairo UniversityEgypt
Vertebral AugmentationVertebroplasty
(1984): Injection of material (usually PMMA cement) into vertebral body
Kyphoplasty
(1998): Injection after manipulation involving cavity creation
Pain associated with
Compression vertebral fractures
• Primary osteoporosis• steroid-induced osteoporosis• Neoplastic-induced fracture• Sub-acute traumatic collapse• Vertebral angiomas • Symptomatic microfracture [MRI] • Lytic lesion [CT] without loss of vertebral height
Predictors of fracture
19.2% a second fracture within one year
24% a further fracture within a year
Percutaneous VP and KP Simple procedures
However, must be treated with respect, as its application, without appropriate preparation
and physician knowledge, can quickly produce increased pain, permanent neurologic injury,
and even death
Local
GeneralNeurolepto
AnaesthesiaAnaesthesia
Election will depend on surgeon’s experience and characteristics of patient.
The three steps of vertebroplasty: 1. placement of a guide wire
2. insertion of a working cannula 3. injection of cement filler
The five steps of kyphoplasty: 1. placement of a guide wire
2. insertion of a working cannula 3. reaming working channels beyond the cannula tips4. balloon insertion, inflation, deflation, and removal
5. injection of void filler
Transpedicular Approach
Bilateral Transpedicular Approach
Unilateral Transpedicular Vertebroplasty
Injection of bone cement (methyl-methacrylate)
Kyphoplasty
Parapedicular Approach(lateral to pedicle and above the
transverse process)
This avoids the exiting nerve root (courses under the pedicle)The needle entry site along the lateral aspect of the vertebra
Does not allow local pressure after needle removal, the chance for bleeding higher than with the transpedicular approach
Lateral Extrapedicular Approach utilizes Effective Pedicle
(the rib-pedicle complex)
The instrument must also be angulated more toward the midline to avoid lateral penetration
of the vertebral body
Anterior Cervical Approach
Manual displacement of the carotid–jugular complex and guide needle insertion
Needle position can be confirmed with CT.
Typical biplane configuration
Combined CT and mobile fluoroscopy SETUP
The skin incision is 1 cm lateral of entry point
for L1 to L4, and 2 cm lateral for L5
Starting point of right transpedicular access between 1 and 3 o’clock
Starting point of left transpedicular access between 9 and 11 o’clock
Ending points for transpedicular access
Convergence towards the midline, which however should not be crossed
Safety for injection
Pictorial of trajectory ‘‘stopping points’’
to ensure safe placement of the Jamshidi needle
Safety for cement injection
The tip at the junction of the anterior and middle third of the vertebra away from the large venous
confluence in the posterior of the vertebra
The second needle
The white line shows its trajectory
predict the ultimate needle tract
make adjustments
Cement injection is the last step in all levels
It is important to fill the anterior 2/3–3/4
of the vertebral body
Cement should reach or cross the midline to reinforce both halves of the vertebra (white
arrows)
A Unipedicular VP
shows distribution of cement into
both halves of the vertebra
Inflatable ballon in the midline of the fractured body
Tip of the guide pin over the center of the vertebral body
Kyphoplasty – “The Good”
• A modification of the vertebroplasty procedure to:– restore vertebral
body height– Low risk of clinically
evident cement extravasation.
Kyphoplasty – “The Bad”
• There is still a risk of extravasation• Close analysis of literature indicates height
restorations as an insignificant result.
Kyphoplasty – “The Ugly”
• The big question, “Is this cost justified (when compared to vertebroplasty) for the added safety?”
• Most studies are retrospective analyses. This is an area ripe for further analysis10.
Pearls and Pitfalls
Cement Extrusion
Kyphoplasty with small amount of anterior(white arrow) and lateral (black arrow) cement extrusion
rarely associated with clinical sequelae
However, leakage may be significant !!
To prevent rare significant neurologic deficit associated with PVP, intact posterior vertebral body cortex is one
of the most important prerequisite that must be thoroughly confirmed preoperatively
Cement too liquid when injected tracked backward along the needle path leaving
cement in the soft tissues
In myeloma and osteolytic metastases
Complete destruction of the posterior cortical wall
Special techniques in cases ofmyeloma and osteolytic metastases
• The risk of cement leakage is greater,– the egg-shell technique should be preferred to the
conventional balloon kyphoplasty technique • Pedicles are may be affected by osteolysis,
making transpedicular access no longer safe– a contralateral single approach via a still intact pedicle
or – an extrapedicular approach can be chosen.
• The possibility of dislocation of the cement block has to be taken into account if the anterior cortical substance is missing
Pre Post 1y 3y
Dislocation of the cement
Vertebroplasty of T12 with osteolysis and unknown primary tumor with ventral dislocation of the cement
beginning after 3 weeks
9 months 2 years 3 weeksIntraop.
Cement dislodgement 6 months after the percutaneous vertebroplasty
C7 & T1 Visualization fluoroscopically impossible
shoulders
very small epidural leak of cement (CT guided PV)
Tumor migration with cement injection
Leakage into inferior disc(No clinical consequence)
Cement leak into the disc space (black arrow).
The cement was allowed to harden and the cannula exchanged over a wire so that
subsequent cement injection could take place
The severe collapse
extreme compression of T12 with residual marrow space
Height restoration with traction
A bilateral transpedicular approachPedicle of collapsed vertebra seen
Trajectory through the lower aspect of the pedicle parallel to the residual endplates to access the
anterior part of the vertebral body
The amount of cement into an extremely collapsed vertebra much smaller than is usually used for less collapsed vertebrae
Digital subtraction venogram
The contrast leak is not predictive of where the cement go. Also, the contrast obscures detection of early cement leak
Difficult Reductions: Balloon does not inflate adequately
Using the Bone Curette• in older fractures• a specially designed curette retracted and
advanced to score the bone in the region. • The curette is removed, and balloon inflation
is again attempted.
Standard balloons, eccentric expansion with risk of blowout of the vertebral walls or endplates
a directional balloon tamp may be desired
Vertebral Body Breakthrough: EggshellTechnique of Containing Bone Cement
Partial loss of reduction after balloons deflated … Lordoplasty
(indirect reduction maneuver)
Sacroplasty
Sacral insufficiency fracturesBest performed under CT guidance.
Burst fracture of L1
With good reduction one month after instrumentation removal
(18 months posttrauma)
Developments…..
• Calcium phosphate in young patients with traumatic fractures
• Prophylaxis by adding chemotherapy agents or radioactive isotopes to the cement in tumour