Keywords
nonunion - traumatic spondylolisthesis of the axis - low-intensity pulsed ultrasound
- bone union
Introduction
Traumatic spondylolisthesis of the axis is considered one of the most frequent forms
of upper cervical spine injury. The injury comprises 4 to 7% of all traumatic cervical
spine fractures and is classified based on the system described by Effendi et al with
modifications proposed by Levine and Edwards (L–E).[1] Recent studies suggest that based on the L–E system, type I and type II traumatic
spondylolisthesis of the axis have been satisfactorily treated, mostly using a conservative
approach, which can result in a progressively improved function, a low incidence of
neurological deficits, and complications.[2]
[3] The majority of cases of traumatic spondylolisthesis of the axis can be treated
nonoperatively with reduction and subsequent immobilization in a rigid cervical collar
or halo device. For unstable fractures, including some L–E type II and most type IIa/III
fractures, or when external brace immobilization is ineffective (for example, in cases
of delayed unions or nonunions), surgical management is indicated and can be accomplished
by using either anterior or posterior fusion techniques.[4] Although surgical techniques for traumatic spondylolisthesis of the axis have advanced,
problems, such as the risk of neurovascular injury and postoperative complications
still remain.[5]
[6]
A low-intensity pulsed ultrasound (LIPUS) device has been developed for the acceleration
of fracture healing. Recent studies have reported the benefits of LIPUS for fresh
fractures as well as delayed unions and nonunions.[7]
[8] These results suggest that LIPUS could be used as an alternative treatment to surgery.
Herein, we report a unique case of delayed union of a traumatic spondylolisthesis
of the axis that was successfully treated with halo immobilization and LIPUS. To the
best of our knowledge, this is the first report showing that LIPUS might be a feasible
treatment for cervical spine fractures.
Case Report
A 20-year-old woman presented with neck pain after the cervical trauma that occurred
during a motor vehicle accident. Plain radiographs and computed tomography (CT) scans
of the cervical vertebrae showed type I traumatic spondylolisthesis of the axis using
the modified L–E classification. Conservative therapy with a rigid cervical collar
was the immediate postinjury treatment used. After 12 weeks of the injury, the patient
was referred to our orthopedic department because of nonunion and development of angulation
and displacement ([Fig. 1]). An initial examination in our department did not reveal the presence of any neurologic
deficit. The patient was placed in a neutral position with her head and neck in a
halo vest. Immediately after halo immobilization, treatment with a LIPUS device (SAFHS
4000J; Teijin Pharma, Tokyo, Japan) was applied for 20 minutes once daily to the right
and left fracture sites after marking the fracture position under fluoroscopic guidance
([Fig. 2]). The LIPUS device had a frequency of 1.5 MHz, a signal burst width of 200 μs, a
signal repetition frequency of 1 kHz, and an intensity of 30 mW/cm2. Radiographs and a CT scan showed improved healing of the fracture 3 and 10 weeks
after the initiation of LIPUS ([Fig. 3]). After 11 weeks of starting LIPUS was started, the halo vest was removed, and the
patient had structurally and functionally recovered. The clinical follow-up at 12
months revealed no symptoms, such as neck pain and discomfort, which suggest pseudarthrosis.
Because the application of LIPUS for spinal fractures is considered to be an off-label
use of this device, it was approved by the ethical committee of Yamanashi University
before LIPUS treatment was started (approval number: 152).
Fig. 1 (A) Cervical plain radiograph at the time of injury and (B) 3 months later. The white arrow denotes delayed union and the development of angulation
and displacement.
Fig. 2 Macroscopic picture showing low-intensity pulsed ultrasound being used as an adjuvant
therapy after halo immobilization.
Fig. 3 (A) Radiographs with an arrow showing the C2 vertebra at admission, 3 weeks after initiation
of low-intensity pulsed ultrasound (LIPUS), and 10 weeks after initiation of LIPUS.
(B) Computed tomography (CT) scans showing, lateral (right and left side) views at admission,
3 weeks after initiation of LIPUS, and 10 weeks after initiation of LIPUS, and axial
views (bottom two panels) of C2 vertebra at 3 and 10 weeks after the initiation of
LIPUS. White lines indicate the locations of the sagittal sections. Favorable healing
of the fracture can be seen on the radiographs, and CT scans taken after initiation
of LIPUS. (C) Time series of treatments was shown.
Discussion
Both delayed and nonunions can lead to additional suffering, and prolonged functional
impairment for patients, as well as increased health care system costs.[9] Delayed unions, and nonunions often require additional complex surgical procedures
to heal.[10] In the current case, 3 months of conservative therapy using a cervical collar failed
to prevent increasingly severe angulation and displacement indicative of instability
at the fracture site. For unstable fractures that are the result of traumatic spondylolisthesis
of the axis (including some L–E type II and most type IIa/III fractures, or when external
brace immobilization is ineffective), surgical management is indicated.[1]
When the decision to proceed with surgical fixation has been made, the various surgical
techniques suggested include a posterior approach, an anterior approach or a combined
anterior and posterior approach.[11] The anatomy of the upper cervical spine has large individual variations, and the
presence of surrounding neurovascular structures makes pedicle screw fixations even
more technically challenging. Misplacement and complications of pedicle screws placed
using fluoroscopic techniques have been reported in up to 21.6% of cervical trauma
patients.[12] In contrast, the disadvantage of conservative treatment with the halo device is
prolonged immobilization for an additional 3 to 6 months with an uncertain outcome.
Therefore, after halo immobilization, and before any decision being made to proceed
with surgical fixation, we proposed the use of LIPUS as an adjuvant therapy and obtained
an excellent outcome. We could see evidence of bone union only 10 weeks after the
initiation of conservative treatment using halo immobilization. Importantly, we did
not observe any adverse events.
It has been reported that clinical success rates with LIPUS for delayed unions and
nonunions in long bones can range from 67 to 90%.[13] Interestingly, a positive effect of LIPUS on spinal fusion has been demonstrated
in several animal experiments.[8]
[14]
[15] However, clinical data are completely lacking with respect to the efficacy and safety
of LIPUS for spinal fractures in humans. Despite this, based on the current case we
cannot conclude LIPUS alone can achieve a successful union in the case of previously
delayed unions and nonunions of traumatic spondylolisthesis of the axis, but these
results might indicate the combination of halo immobilization and LIPUS can synergistically
induce bone union.
To the best of our knowledge, this is the first report describing that the combination
of halo immobilization and LIPUS therapy might be a safe, effective, and feasible
method by which to treat cervical spine fractures.
