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Osteoporotic VCFs usually lead to back pain, loss of height, kyphotic deformity, and
a reduction in quality of life 29]. PVP and PKP are cement augmentation procedures used to control pain and restore
function in patients with osteoporotic VCFs that are refractory to conservative treatment
1]-8],30]. But some studies showed the recurrent fracture of a previously operated vertebra
or adjacent vertebral fracture after PVP or PKP 3],11]-23].

Fuentes et al. 26] used PKP associated with percutaneous short-segment cannulated pedicle screw osteosynthesis
in 18 patients of burst vertebral fractures without neurological deficits. The mean
vertebral height was improved by 25%, and a mean improvement of 11.28°in the local
kyphotic angle was obtained. No significant changes in the results obtained were observed
at the end of the follow-up period. Verlaan et al. 24],25] performed balloon kyphoplasty in combination with pedicle screw instrumentation to
treat thoracic and lumbar burst fractures. The postoperative radiographs and computer
tomography or magnetic resonance images demonstrated a good fracture reduction and
filling of the bone defect without unwarranted bone displacement. There was no instrumentation
failure or measurable loss of sagittal curve and vertebral height correction in the
follow-up. We designed the MIPS combined with PVP technique 27] for osteoporotic VCF in order to prevent the occurrence of secondary VCF after PVP.

The feasibility and relative safety of MIPS combined with PVP were confirmed by the
fact that postoperative radiographs and scanographic images showed that the screws
and cement were all properly positioned in the patients of group 2. None of the patients
were found to have any postoperative neurological complications. Like all surgical
interventions, pedicle screw stabilization is not devoid of risks, since it can cause
nerve injuries. The pedicle must be carefully probed in all four quadrants to be sure
that a solid tube of bone exists and that violation into the spinal canal or inferiorly
into the neuroforamen has not occurred before the pedicle screws were implanted into
the vertebrae with minimally invasive technique under direct vision in our study.
Cement injection also involves risks of complications including cement leakage into
the spinal canal, which is greater when the posterior wall has been damaged. During
the PVP procedure, we injected bone cement into the target vertebral body under constant
fluoroscopy, which must be stopped if the cement got close to the posterior aspect
of the vertebral body or leaked into an extraosseous space. All of these measures
were taken to avoid the occurrence of neurological deficits and guarantee the safety
of operation.

MIPS combined with PVP was compared with PVP to evaluate its rate of secondary fracture
after PVP in this study. The results showed that 18.2?±?3.9° of Cobb angle before
surgery significantly decreased to 7.3?±?3.2° immediately after surgery in group 2
(P??0.005). The central vertebral body height significantly increased from 43.4?±?7.4%
before surgery to 72.8?±?6.5% of the estimated intact central height immediately after
surgery (P??0.005). The anterior vertebral body height significantly increased from 49.7?±?8.0%
before surgery to 81.2?±?6.6% of the estimated intact anterior height immediately
after surgery (P??0.005). It is more important that the correction obtained of both the Cobb angle
and the vertebral body height was stable in time with a minimal loss of correction
at final follow-up (0.7° of kyphosis, 3.5% of central vertebral height, and 3.4% of
anterior vertebral height after 2 years) which seemed to occur during the 2 months
after surgery. No fracture of the operated or adjacent vertebral body was found in
group of MIPS combined with PVP. But the Cobb angle significantly increased (P??0.005), and the central and anterior vertebral body height significantly decreased
(P??0.005), 2 years after surgery compared with those immediately after surgery in
group of PVP. There were five (13.5%) patients with new fracture of operated vertebrae
and nine (24.3%) cases with fracture of adjacent vertebrae, which is similar to other
studies 4],11]-23]. Although there was no significant difference in VAS 6 months, 1 year, and 2 years
after surgery between groups, VAS in group of PVP was higher than those in group of
MIPS and PVP. These scores included high VAS of refractured patients with more back
pain, who underwent conservative treatment such as bed rest and medication.

The fracture was reduced by the combination of the method of installation and proper
distraction applied between two screws as necessary before PVP in group 2, which is
better than only by installation supported by the results that the Cobb angle, the
central and anterior height of group 2 was significantly better (P??0.005) than those of group 1 immediately after surgery. Short-segment pedicle screw
instrumentation is a well described technique to reduce and stabilize thoracic and
lumbar spine fractures 31],32]. It is a relatively easy procedure but the means of augmenting the anterior column
are limited. Hardware failure and a loss of reduction are recognized complications
caused by insufficient anterior column support 33]-35], even in young patients in whom resistance to pedicle screw pull-out is high. It
is known that cement-based vertebroplasty can restore, even increase, strength and
stiffness after VCFs in osteoporotic specimens 36]-40]. Vertebroplasty with cement after posterior instrumentation might reduce the load
on the pedicle screw, hardware failure, and anterior column collapse 41]. This conclusion was also supported by the results of our study in which there is
no hardware failure in any patient during follow-up after instrumentation insertion
and PVP, although the mean age of these patients was 73.9 years. These data gave us
more confidence to use the pedicle screw fixation in elderly patients.

In this series, the minimal-access in the paraspinal sacrospinalis muscle-splitting
(Wiltse) approach 28] was performed to insert non-cannulated pedicle screws into the vertebrae and two
rods of the appropriate size were placed over the pedicle screws through subcutaneous
soft tissues and muscles. Unlike the traditional midline incision, Wiltse approach
protected the attachment of muscle to bone, avoid disruption of the supraspinous and
interspinous ligaments, provided a more direct approach to the transverse processes
and pedicles, and decreased bleeding and postoperative pain 42]-44]. In the group of MIPS and PVP, the duration of the operation was 74.7?±?8.6 min,
the blood loss was 70.2?±?4.7 ml, and the stay at hospital was 5.3?±?1.0 days. These
values were considered acceptable although there were significant differences compared
with the group of PVP (P?=?0.000). The pain intensity level on the VAS significantly dropped from 9.1?±?1.0
of pre-operation to 2.4?±?0.9 (P??0.005) immediately after the operation in the group of MIPS and PVP, which was
similar to that in the group of PVP. The results show that MIPS only devote the limited
additional trauma to PVP (Figure 6). If the patient with refracture after PVP has severe back pain or neurological compression
symptom, the additional treatment such as revision surgery will consume more manpower,
material, and financial resources, and the patient will suffer more trauma. Compared
with percutaneous pedicle screws, minimally invasive non-cannulated pedicle screw
fixation has the incisions of similar size, but easier manipulation and less fluoroscopic
monitor during the operation. The common pedicle screws used in this technique were
much cheaper than the percutaneous cannulated ones.

Figure 6. Minimally invasive access: cosmetic results obtained after the insertion of pedicle
screws and PVP (1 month after surgery).