3D Kinematic Analysis for the Functional Evaluation in the Rat Model of Sciatic Nerve Crush Injury

We provide a precise and DiCharacter method for functional evaluations of laboratory animals. It is sensitive and reliable and devoid of shortcomings attributed to other methods for functional evaluations. For example, the sciatic functional index.

To begin, set up two transparent plastic sheets on both sides of the treadmill to let a 12-week-old male LEWIS rat walk in a straight frontward direction, then turn on the electric shock grid. Have each rat walk on the treadmill. Gradually accelerate the treadmill to the desired speed of 20 centimeters per second and let the rat walk normally at this speed for five minutes.

After each walking session, provide a one to two-minute rest break. Repeat this process three times per day five days per week for one week. While the rat is receiving stable anesthesia through the anesthetic mask, shave an area from the lower back to the bilateral malleoli using an electric shaver.

Place the rat in the prone position. Use a black marker pen to mark the bone landmarks on the shaved skin, a line through the spinous processes from the lumbar to sacral vertebrae. Additionally, use a black marker to mark the anterior/superior iliac spines, the greater trochanters, the knee joints, the lateral malleoli, the fifth metatarsal phalangeal joints, and the tip of the fourth toe.

Then use a liquid adhesive to attach hemispheric markers to these bone landmarks except for the line through the spinous processes from the lumbar to the sacral vertebrae and the tip of the fourth toe. After placing all the markers, put the rat back into the cage. Do not put the rat on the treadmill until it fully recovers from anesthesia.

Set up two transparent plastic sheets on both sides of the treadmill and place the calibration box in the middle of the treadmill. Open the recording software and then click on the calibration image icon on the display. Click the recording icon to record one to two seconds of video from four directions using 120 hertz CCD cameras.

Click on the recording icon again to stop the recording. Open the video files in the calculation software. Click and drag the characteristic points of the calibration box 3D models on the bottom right corner of the screen to the corresponding markers on the four pictures which are automatically transformed from the video in the calibration pattern.

Then click on the save icon. Now take the calibration box out of the treadmill, turn on the electric shock grid, and place the fully awake rat on the treadmill. Open the recording software and input the basic information about the rat including its serial number, walking speed, and the name of the principal operator.

Turn on the treadmill and set the speed to 20 centimeters per second. After the rat adapts to the speed and is able to walk normally, click the recording icon on the display to record the walking rat with the four cameras. Once over 10 steps are recorded, click on the icon again to stop recording and turn off the treadmill.

Put the rat back into the anesthesia induction chamber for anesthetization. While the rat is under continuous anesthesia via the anesthetic mask, remove the hemispheric markers. Open the calculation software and open the video file on the interface.

Click and drag the bilateral control bar on the progress bar of the video to ensure that only a 10-step treadmill walking record is displayed. Click and drag each characteristic point from the 3D model on the bottom right corner of the screen to the corresponding marker on each of the four initial pictures of the videos that were taken by the cameras. Then click on the automatically tracing icon to start the automatic marker tracing process.

If the system does not accurately trace a marker, click on the manually digitize icon to switch to the manual tracing mode, click on the tracing characteristic point in the 3D model and then on the responding marker in the picture. Once the marker is clicked, ensure that the picture switches to the next frame of the video. Now continuously click on the marker until the marker tracing process is completed.

Once finished, click on the save icon. Open the analysis software and then open the processed video file on the interface. Click on the setting icon and select and add designated parameters such as the ankle angle, toe angle, and pelvic shift to the display list in the popup window on the right.

Click on OK so that the curves representing the value changes in the parameters appear on the interface. Click on the measurement icon and select smooth processing in its pull down menu. Enter 20 hertz in the popup window to remove frequencies greater than 20 hertz within the curves.

By means of 3D kinematic analysis, the mean ratio of the stance or swing phase in the 10-step cycle was automatically calculated and represented on the interface. Each bilateral stance and swing phase in 10-step cycle periods for the control group, one week post-surgery, three weeks post-surgery, and six weeks post-surgery groups are shown here. The normal center of gravity trajectory shape resembles the infinity sign.

The center of gravity trajectory shape did not return to a normal shape until six weeks after surgery. The mean value of the ankle or toe angle in the toe off phase suggested that they improved in an upward direction after surgery. Locating the bone landmarks on shaved skin as carefully and correctly as possible is most important thing.

analysis on the sciatic nerve can be performed and it will reveal the relationship between functional and histological changes.