lenke.qxp 24/4/08 10:13 Page 52
Orthopaedic Surgery Spine
Scoliosis and Chest Wall Derotation Utilising Pedicle Screws and the
Vertebral Column Manipulator Device
a report by
Lawrence G Lenke
Jerome J Gilden Professor of Orthopaedic Surgery, and Professor of Neurological Surgery, Washington University School of Medicine
The revolutionary design and capabilities of the Cotrel–Dubousset scoliosis through periapical derotation. As with any new principle, there
(CD
®
) Spinal Instrumentation System transformed the treatment of are many techniques available to accomplish this periapical derotation.
spinal deformities when it was introduced in the early 1980s. Utilising fixed-angle pedicle screws at the apex provided significantly
Prior to that, for nearly 20 years hooks were the primary implant used more derotation effect than multiaxial screws because of the more direct
for fixation to the thoracic vertebrae. However, in the 1990s surgeons relationship between screw derotation and vertebra derotation afforded
began to use lumbar and thoracolumbar pedicle screws at the lower by a fixed-angle screw.
5
Active derotation manoeuvres, consisting of the
end of spinal deformity constructs. Superior results of lumbar pedicle manipulation of either concave apical screws pushed in a lateral
screws used for scoliosis correction have been confirmed at multiple direction or convex periapical screws pushed in a medial direction, may
centres, and the technique continues to be used today. also accomplish periapical derotation. From a biomechanical perspective,
it has been found that pushing and derotating a convex periapical
Since the introduction of CD instrumentation, the most difficult pedicle screw provides a more effective and safer derotation manoeuvre
deformity to correct has been axial plane rotational malalignment. The than manipulating a concave periapical screw.
6
The anatomical rationale
novel 90º rod rotation manoeuvre espoused by Drs Yves Cotrel and stems from the knowledge that the medial pedicle border has stronger
Jean Dubousset was excellent for coronal and sagittal realignment of bone to be able to accommodate the force of a convex periapical screw
scoliosis deformities, but was found to be essentially a translational derotation compared with the weaker lateral vertebral body bone. The
corrective manoeuvre in the axial plane, with minimal true derotation position of the aorta on the left side of the thoracic vertebra also
of the apical vertebrae and ribcage occurring.
1
mandates careful consideration of unilateral concave periapical screw
derotation for fear of displacing the concave tip of the pedicle
However, since the beginning of the new millennium, an increasing screw outside of the vertebral body.
number of scoliosis surgeons around the world have been utilising
pedicle screws in the thoracic spine. This technique has also been Triangulation of both concave and convex pedicle screws is a logical
shown in many centres by many surgeons to be a viable option for consideration in periapical screw derotation. This manoeuvre expands on
thoracic fixation.
2
Surgeons who have switched from hook to screw the initial device for transverse traction (DTT), which linked both sides of
implants in the thoracic spine were initially impressed by the secure the spinal construct together. This principle was also espoused over two
three-column fixation afforded by the screws, the superior control of decades ago by Daniel Chopin, with the knowledge that triangulated
the upper and lower instrumented vertebrae and the ability to manage lumbar pedicle screws were extremely resistant to dorsal pull-out forces
larger scoliosis deformities with a posterior-only approach.
3,4
In compared with non-linked pedicle screws. Based on this biomechanical
addition, a recently noted advantage is the realisation that three- and clinical foundation, the vertebral column manipulator (VCM) device
column screw fixation of the periapical region of a scoliosis deformity was developed.
can provide a mechanism for true apical derotation.
The basic theoretical procedure behind the VCM device is to initially
These recent advances in the safe and efficacious use of both thoracic triangulate periapical pedicle screws, then link these triangulated screw
and lumbar pedicle screw fixation in scoliotic vertebrae have constructs together into a ‘quadrilateral’ frame for maximum periapical
consequently provided an opportunity for advancing 3D realignment of pedicle screw capture, control and stress distribution. Intuitively, greater
numbers of periapical pedicle screws captured and cohesively
manipulated will decrease the stresses on individual bone–screw
Lawrence G Lenke is the Jerome J Gilden Professor of
Orthopaedic Surgery and a Professor of Neurological
interfaces. This principle has been validated in a biomechanical cadaver
Surgery at Washington University School of Medicine, where
study by Cheng and colleagues.
7
They found an increasing degree of
he is also Co-Chief of Adult and Paediatric Scoliosis and
overall device stability with decreasing degrees of bone–screw interface
Reconstructive Spinal Surgery. His practical interests include
reconstruction and the treatment of scoliosis, kyphosis, flat- loosening, going from manipulation of a single periapical pedicle screw,
back syndrome and spondylolisthesis. He is an active
to a unilateral linked system, to a triangulated system, to a quadrilateral
member of the American Academy of Orthopaedic Surgeons
(AAOS), the American Medical Association (AMA), the
frame mechanism as provided by the VCM device.
American Orthopaedic Association (AOA) and the Scoliosis Research Society (SRS), and has
won six awards from the SRS and three from the AOA. Dr Lenke received his medical degree
The components of the VCM instruments consist of a derotator implant
from Northwestern University and completed his internship and residency training at
Washington University School of Medicine in St Louis.
holder that attaches to the side wall of a fixed or multiaxial LEGACY™
E:
lenkel@wustl.edu
pedicle screw, a derotator bridge that connects to the derotator implant
holder with a derotator bridge nut and derotator bridge handles that
52 © TOUCH BRIEFINGS 2008
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92