If you have an issue with the "Hip Joint Center" calibration step
This is the second step of the calibration phase. The patient must perform a circular movement with the assessed leg.
For this step, the KneeKG-3D–Tracker-FemoralTM and the KneeKG-3D-PelvisTM must be GREEN.
If you have an issue with this step, here are a few tips:
Visibility of the KneeKG-3D-TrackersTM
Make sure all the needed trackers (KneeKG-3D–Tracker-FemoralTM and the KneeKG-3D-PelvisTM) are in the field of view of the NDI camera or that the visibility is not obstructed.
If the patient is tall, you may need to tilt up the camera so the pelvis tracker is in the field of view of the camera.
Patient Positioning
For this movement, the patient must be perpendicular to the camera.
- Install the KneeKG-T-BlockTM as a guide to indicate the direction that the patient’s hips and shoulders will face. ( The T-Block will also help to give them some height above the treadmill so the circular hip motion can be performed comfortably).
- Ask the patient to look straight forward, stabilize their core and perform a circular movement with the assessed leg, both in front of and behind their trunk. (The patient may hold on to the treadmill for support.)
- Start the recording.
Remember, you can always help the patient stabilize their pelvis so the trackers remain visible.
How to Help a Patient with Hip Range of Motion Limitation
Some patients have a hip range of motion limitations, requiring a modification to the procedure. There are other possible alternatives to the HJC calibration circumduction:
- A leg swing: The patient performs a simple leg swing in a straight line forward and backward, then side to side, then forward and backward again, and so on.
- A foot slide: Keeping the foot near the treadmill surface, the patient slides their foot forward and then outward and backward in the shape of the letter D, and repeats.
- Assist the patient manually: The Evaluator can hold the patient’s knee or proximal tibia in their hands, without blocking the view of the femoral tracker, and manually move the femur in a circular motion.
Watch this short video to see the alternatives.
