User guide

Charnwood Dynamics Ltd. Coda cx1 User Guide – Gait Analysis II - 3
CX1 USER GUIDE - COMPLETE.doc 26/04/04 87/162
A TYPICAL SESSION IN THE GAIT LABORATORY
The Codamotion system has been designed from the outset to minimize the time and
effort spent preparing motion-capture and analysis in the laboratory. Gait analysis, being
the most prevalent application of Coda, has gained most in efficiency savings throughout
development in consultation with clinicians and laboratory technicians.
Despite the myriad inherent technical complexities and innumerable software options in
the user interface a well-configured system ‘tuned’ to the gait-clinicians requirements
reduces the many tasks of acquiring (segmental) movement data, analysing them and
producing reports to a brief routine easily managed by an unsupported clinician.
Repeated, full 3D segmental gait analyses, whether bilateral or unilateral, may be
accomplished with equal ease in just a few minutes by a well-rehearsed clinician
operating to an established protocol to generate a standard gait report.
Movement Data Acquisition
Before running the Codamotion Analysis program, the user will have switched
everything on (Coda scanners, force-plate amplifier, etc..), the marker drive-boxes will be
well charged, markers will already be attached to the pelvic frame and leg wands, and
some double-sided tape already cut into short pieces. Then the session begins with the
arrival of the patient, whose database file has already been retrieved for inspection.
The most time consuming task is patient preparation but this need take no longer than 15
minutes for the bilateral kit (less for unilateral). Use of the supplied wands and pelvic
frame will save time since, with markers already attached, they may be quickly fitted with
their drive boxes and then strapped to the patient ready-wired. The pelvic frame is easily
adjusted to align with pelvic landmarks, the sacral wand fitting snugly against the sacrum
which should lie mid-way between the ‘PSIS’ markers at the back of the frame. The
femoral wand should be turned about its hinge to bring it into alignment with the forward
direction of the femur. The tibial wand is likewise aligned with the ankle, possibly with the
aid of the jig provided. Marker positioning on the wands is not critical since they are only
defining orientation.
The knee and foot markers (and their boxes) are attached directly to the skin and their
positioning is more critical since they will define the knee and ankle joints.
Before the final marker and box are attached they should be used to set the ‘origin’. The
origin must be set once per session (it will be remembered until the software is closed
down and remains valid for all acquisitions provided the Coda machines aren’t moved).
Any marker may be placed at the exact centre of the force plate (essential for
calculations of moments and powers) and from the CODA menu ‘Define Marker Origin...’
is selected. A bleep confirms the operation.
(If EMG data are to be acquired the optional EMG paraphernalia must also be attached at
this stage.)
It is vitally important to connect markers in given positions with drive box numbers
corresponding to the (usual) gait-model setup, as represented in the usual ‘setup’ files.
(Refer to diagrams for the usual marker-number / drive-box setups.)