Non fusion surgery in adolescent idiopathic scoliosis patients using the Nemost system

Scoliosis is a complex three-dimensional deformity of the spine, which occurs
primarily in growing children and adolescents. In adolescent idiopathic
scoliosis (AIS), the cause is unknown. Children with severe and progressive
scoliosis, if left untreated, are at risk of rapid and severe spinal deformity
progression, which can result in a decrease of pulmonary function, poor
cosmetic result and poor quality of life.
Treatment options in AIS depend on curve severity and remaining growth
potential, and include intensive brace treatment for smaller curvatures whereas
surgical correction and spinal fusion is advocated for more severe curves.
Growing rods are used for severe early infantile deformities or early onset
scoliosis (EOS).
Bracing, by using a rigid plastic orthosis, is currently the primary therapy to
prevent curve progression in mild curves up to 45 degrees and skeletal immature
patients. Most braces are recommended to be worn for 18-23 hours per day
during several years (until skeletal maturity has been reached). This may cause
a high level of physical discomfort and emotional and psychological stress in
these patients, and failure of brace treatment therefore is common.
Surgical therapy for AIS is recommended in severe progressive curvatures.
Surgical treatment includes correction of the spinal curvature by using
multisegmental screw fixation and posterior spinal fusion of the thoracolumbar
spine. Complete posterior spinal fusion, however, lacks the possibilities for
future adaptation of natural changes in spinal balance and posture.
Currently, growing rods systems are used as a posterior spinal implant to allow
growth of the spine and thorax and limit progression of the scoliosis in young
patients with early onset scoliosis. Growing rods systems are distractable
spinal implants, with bipolar anchorage fixations to the upper and lower part
of the spine, using posterior spinal instrumentation such as hooks and pedicle
screws.
The Nemost growing system, developed by the EUROS Compagny, is a CE-marked
commercial available medical device for the treatment of early onset
neuromuscular or early onset idiopathic scoliosis. It is a non-fusion, growth
enabling system with bipolar fixation intended to be used with a posterior
spinal instrumentation.
We hypothesize that the use of a minimal invasive non-fusion bipolar posterior
spinal implant (growing rods) can both correct and brace the spine internally
and adapt balance or distraction as the AIS-patient grows.

The primary objective of the study is to monitor the effectiveness of the
NEMOST Growing Domino to correct the scoliotic curve in growing patients
suffering from progressive adolescent idiopathic scoliosis who have failed
conservative treatment.

This study is a cohort study

Application of Nemost-AIS

The risks associated with participation can be considered moderate. The system
is CE-marked and is already in use to treat patients with AIS. However, no
clinical trials have been published for this patient group, so far.
In patients suffering from neuromuscular scoliosis, the system is found to
correct the scoliotic curve from 89° to 35° (Miladi 2018) and is well tolerated
by the patients. The Nemost system could be beneficial to the subject as it is
expected to decrease operative intervention and the associated complications in
comparison to conventional spinal fusion surgery.
The Nemost growing system is expected to perform as least as well as
conventional spinal fusion systems with less complications at long term. The
surgical burden and risks are not different, or even less compared to
conventional growth sparing surgical procedures, as other system requires
re-operations to distract the system.

The Nemost system requires surgery, increasing the burden and risks compared to
observational treatment. On the other hand, the risk of a necessarry definitive
fusion surgery will be decreased. This kind of surgery comes with higher risk
and a higher radiological burden compared to Nemost-AIS placement.
Compared to observational treatment, the

Potential risks of the treatment using the Nemost system are: 1) system
failures; 2) curve progression dispite Nemost-AIS; 3) risks of surgery like
wound infection, neurological injury, bleeding, failure of implant (breakage,
or breaking out of the system).
Potential advantages of the system compared to brace treatment is the decreased
risk on definitive spinal fusion, concerning an increased operative risk and
higher radiological burden.
Considering the clinical experience, and the results from literature concerning
patients suffering from neuromuscular scoliosis, we conclude a moderate risk.