Clinical usability of non-contact scanners in measuring stumpvolume of transtibial amputee patients

One of the predictors of good functioning in transtibial amputee patients is a
good prothesis fit. For a definitive prosthesis to fit well, it is necessary to
have a stable stump volume and shape. The volume and shape of a stump changes
over time and becomes more stable several weeks after the operation. Even in
this stable fase there are still changes in volume during the day. There is no
standard in the way this can be determined. Methods to measure volume are the
water immersion method, circumferential measurements, computed tomography scans
and ultrasound measurement.
Previous research compared different methods (water immersion, computer-aided
design (CAD) photometric method, CAD hand scanner and circumferential
measurements)on stump models and transtibial amputee patients. It seemed that
the CAD hand scanner (Omega Tracer) has the smallest repeatability coefficient,
in stump models and amputee patients. A new generation of hand held scanners
has been developed recently. These have been tested in stump models, where
there proved to be small differences in repeatability and also for user
satisfaction with system usability.6 It is necessary to repeat this research in
amputee patients to measure the reliability of the system and the method,
because the interaction between amputee stumps and the systems will be
different than between stump models and systems.
The study of Kofman et al showed repeatability and inter-observer error
variance, but not the patient-CAD system interaction. In order to obtain a
clinically usable stumpvolume measurement system, this study is necessary. Also
the clinical usability needs to be tested in patients, as this was only tested
on models. When finding the most reliable and repeatable measurement method,
the timing of making the definitive prosthesis can be more accurate than it is
now. This makes the functional outcome of amputee patients greater. The study
population should be patients with an uni- or bilateral transtibial amputation,
last operated more than a year ago. In that way the stump volume is as stable
as possible, so the repeated measurements have a small variance and the
reliability of the system can be tested properly.

Primary Objective: What is the reliability and repeatabily of CAD/CAM systems
in measuring stump volume in transtibial amputee patients? Is there a
significant difference in measured stumpvolumes in patients per system?

Secondary Objective(s): Are the CAD/CAM systems usable in clinical practice
according to researcher and patient satisfaction? Is the system simple and
quick enough to use in clinical practice?

This study will be an experimental design, where patients have to visit the
hospital (Isala, Zwolle, the Netherlands) twice for an hour in the period
January-December 2017. There will be two researchers who perform the
measurements with the 4 different CAD/CAM systems. The researchers have 1 test
session to learn how to use the systems. Every stump will be measured while the
patient is sitting on the edge of a research table with with an extended knee
on the amputated side. If there is a flexion contracture of the knee of more
than 15 degrees, the leg has to be lifted in the air with the hip flected in 45
degrees. This is necessary moving around the whole stump with the scanners.
Time to perform the measurement per system will be noted, together with the
stumpvolume measured from the patella tendon point and femur condyles and
patient*s satisfaction.
When all the measurements have been carried out, the data will be stored in
research manager data base and analysed by the head researcher (drs. R.
Kofman).

There is no potential risk for patients attending this study. They have to come
to the hospital twice, and at the hospital they need to make a transfer to a
research table which may involve the risk of falling. The participants will get
a travel- and expenses imbursement. The medical devices used in this study are
already approved for using in patients according to European safety standards
(CE).
The benefit for this group of patients is not directly related to the study.
The possible benefits are for the future a quicker, easier and more reliable
procedure for the timing and fitting of a definitive prosthesis.