With the identification of literature shortfalls on the techniques employed in intraoperative navigated (ION) spinal surgery, we outline a number of measures which have been synthesised into a coherent operative technique. These include positioning, dissection, management of the reference frame, the grip, the angle of attack, the drill, the template, the pedicle screw, the wire, and navigated intrathecal analgesia. Optimizing techniques to improve accuracy allow an overall reduction of the repetition of the surgical steps with its associated productivity benefits including time, cost, radiation, and safety. Cite this article:
Percutaneous placement of pedicle screws is a
well-established technique, however, no studies have compared percutaneous
and open placement of screws in the thoracic spine. The aim of this
cadaveric study was to compare the accuracy and safety of these
techniques at the thoracic spinal level. A total of 288 screws were
inserted in 16 (eight cadavers, 144 screws in percutaneous and eight
cadavers, 144 screws in open). Pedicle perforations and fractures
were documented subsequent to wide laminectomy followed by skeletalisation
of the vertebrae. The perforations were classified as grade 0: no
perforation, grade 1: <
2 mm perforation, grade 2: 2 mm to 4
mm perforation and grade 3: >
4 mm perforation. In the percutaneous
group, the perforation rate was 11.1% with 15 (10.4%) grade 1 and
one (0.7%) grade 2 perforations. In the open group, the perforation
rate was 8.3% (12 screws) and all were grade 1. This difference
was not significant (p = 0.45). There were 19 (13.2%) pedicle fractures
in the percutaneous group and 21 (14.6%) in the open group (p =
0.73). In summary, the safety of percutaneous fluoroscopy-guided
pedicle screw placement in the thoracic spine between T4 and T12
is similar to that of the conventional open technique. Cite this article:
In patients with osteoporosis there is always
a strong possibility that pedicle screws will loosen. This makes
it difficult to select the appropriate osteoporotic patient for
a spinal fusion. The purpose of this study was to determine the
correlation between bone mineral density (BMD) and the magnitude
of torque required to insert a pedicle screw. To accomplish this,
181 patients with degenerative disease of the lumbar spine were
studied prospectively. Each underwent dual-energy x-ray absorptiometry
(DEXA) and intra-operative measurement of the torque required to
insert each pedicle screw. The levels of torque generated in patients
with osteoporosis and osteopenia were significantly lower than those
achieved in normal patients. Positive correlations were observed between
BMD and T-value at the instrumented lumbar vertebrae, mean BMD and
mean T-value of the lumbar vertebrae, and mean BMD and mean T-value
of the proximal femur. The predictive torque (Nm) generated during pedicle
screw insertion was [-0.127 + 1.62 × (BMD at the corresponding lumbar
vertebrae)], as measured by linear regression analysis. The positive
correlation between BMD and the maximum torque required to insert
a pedicle screw suggests that pre-operative assessment of BMD may
be useful in determining the ultimate strength of fixation of a
device, as well as the number of levels that need to be fixed with
pedicle screws in patients who are suspected of having osteoporosis.
We reviewed 212 consecutive patients with adolescent
idiopathic scoliosis who underwent posterior spinal arthrodesis
using all pedicle screw instrumentation in terms of clinical, radiological
and Scoliosis Research Society (SRS)-22 outcomes. In Group 1 (51
patients), the correction was performed over two rods using bilateral
segmental pedicle screws. In Group 2 (161 patients), the correction
was performed over one rod using unilateral segmental pedicle screws
with the second rod providing stability of the construct
through two-level screw fixation at proximal and distal ends. The
mean age at surgery was
14.8 years in both groups. Comparison between groups showed no significant
differences with regard to age and Risser grade at surgery, pre-
and post-operative scoliosis angle, coronal Cobb correction, length
of hospital stay and SRS scores. Correction of upper thoracic curves
was significantly better in Group 1 (p = 0.02). Increased surgical time
and intra-operative blood loss was recorded in Group 1 (p <
0.001
and p = 0.04, respectively). The implant cost was reduced by mean
35% in Group 2 due to the lesser number of pedicle screws. Unilateral and bilateral pedicle screw techniques have both achieved
excellent deformity correction in adolescent patients with idiopathic
scoliosis, which was maintained at two-year follow-up. This has
been associated with high patient satisfaction and low complication
rates.
Traumatic atlanto-occipital dislocation in adults is usually fatal and survival without neurological deficit is rare. The surgical management of those who do survive is difficult and controversial. Most authorities recommend posterior occipitoaxial fusion, but this compromises cervical rotation. We describe a case in which a patient with a traumatic atlanto-occipital disruption but no neurological deficit was treated by atlanto-occipital fusion using a new technique consisting of cancellous bone autografting supported by an occipital plate linked by rods to lateral mass screws in the atlas. The technique is described in detail. At one year the neck was stable, radiological fusion had been achieved, and atlantoaxial rotation preserved. The rationale behind this approach is discussed and the relevant literature reviewed. We recommend the technique for injuries of this type.
