Assesment of the stiffness of the trunk by the Scolibed

Scoliosis is a progressive spinal deformation. A new system was developed to
correct scoliosis without the up-to-now inevitable fusion of the spine,
resulting in a completely stiff spine. This non-fusion scoliosis correction
system corrects the spine and keeps it flexible. Since the spine is connected
to the trunk, the trunk is corrected as well.
To determine the optimal correction capacity of this scoliosis correction
device it is necessary to determine the individual stiffness of the patient*s
trunk. To determine the stiffness of the trunk, a device named *Scolibed* was
developed. It is a bed-shaped mechanical system, divided into a lower and upper
part, connected by an axis. By placing the patient on his back on the table,
both lateral bending and torsional stiffness can be measured. By placing the
patient on his side, flexion and extension stiffness can be measured.
It is unknown whether the device can measure the stiffness in a reproducible
way and whether there is a large individual variation. From a scientific point
of view it is interesting to know if the stiffness of a scoliotic spine is
different from a healthy one, since it may provide information about the
underlying mechanisms of scoliosis, which are unknown up to now.
The first phase of the study is a pilot study to assess the reproducibility of
the device to observe and compare the variation in stiffness found among
healthy subjects and scoliotic patients. The results of the first phase will be
used as the basis for the second phase, a case-control study assessing truncal
stiffness in healthy subjects and patients.

Determine the repeatability, inter and intra-observer variability of the
*Scolibed*. Determine the variation in stiffness for healthy individuals and
for scoliotic patients. Compare the results of healthy individuals and
scoliotic patients.

Interventional pilot study

Design
Interventional pilot study. First phase directed to determine if the device is
reliable and accurate. Second phase is going to be performed to assess the
difference in truncal stiffness between healthy subjects and scoliotic patients.

Duration
First phase: From October 2014 until July 2015.
Second phase: Six to eight months, the starting date depends on the results of
first phase.

Setting
First phase: 15 healthy volunteers to be recruited in Groningen.
15 volunteer scoliotic patients are to be recruited among the patients in
treatment at University Medical Center Groningen (UMCG) by the orthopaedic
surgeons working at the hospital. All measurtements are performes at the UMCG,
dept of Orthopedics.
If a subject shows interest, he or she will be given an Inform Consent Letter
to be signed.

Stiffness of the trunk will be measured.

The subjects are positioned on a vacuum mattress that is fixed to the
*Scolibed* and strapped to the bed with Velcro® straps that are passed over the
subject*s body (two straps over the upper part and three straps over the pelvis
and legs). Then the upper part is rotated relatively to the lower part.
The burden for the subjects are the tightness of the straps, and the unnatural
feeling of being bent. The maximum time for a measurement session is limited to
60 minutes and will be done after a regular appointment with the orthopedic
surgeon in case of patient subjects. Four measurement sessions have to be
performed, three in the same day and one with a time difference of minimum 5
days and maximum 20 days.
The main risk is that the subject is bent too much and will experience pain.
But since this bending is done manually, an immediate stop and movement back is
possible. Other risks are:
• Fracture of the upper and/or lower part of the device and failure of the
fixation of the vacuum mattress to the bed or of the straps, both resulting in
a fall of the subject on the ground. The system has been designed for subjects
of 120 kg with a safety factor of 1,5. The design has been tested with this
load and passed without any signs of failure.
• Electric hazard. The resulting rotation is measured electronically and thus
there is a risk for an electric shock. This risk is very low, since the patient
is lying on a polymer mattress and a wooden bed frame. Moreover, the sensors
are running on low voltage.