Movement Control

Dynamic Knee Flexion

Video-based measurement of knee flexion angle during movement.

Dynamic Knee Flexion tracks the knee flexion angle frame by frame on video during a movement such as a squat. Instead of a static angle, it shows how far and how the knee bends throughout the movement.

What Is It Used For?

Assessing knee flexion under load during functional movement
Tracking recovery of motion after knee surgery or injury
Comparing the difference between right and left knees
Observing squat depth and movement strategy

Measured Parameters

Peak knee flexion angle (degrees)
Knee angle over time throughout the movement
Starting angle and total range
Left-right comparison

Setup and Camera Placement

Place the camera to the side of the tested leg (sagittal plane).
The camera should be fixed at knee-hip height, about 2.5–3 metres away.
The hip, knee and ankle must stay in frame throughout; a full-body view is preferred.
The tested leg should be on the side nearest the camera.

Tips for Accurate Measurement

Prefer shorts or fitted trousers so the hip, knee and ankle are clearly visible.
Put the camera on a tripod or stable surface; avoid handheld recording.
The client should be exactly side-on; rotation towards or away from the camera affects the angle.
Use a well-lit room and a plain background.
If there is pain, limit depth to the client's tolerance.

How Is the Test Done?

Select the client and side, then fix the camera.
The client starts upright with feet shoulder-width apart.
Start recording; the client squats in a controlled manner and returns to the start.
Repeat the movement 3–5 times, then stop recording.
Review the analysis result and save it to the profile.

What Will I See on the Results Screen?

Peak knee flexion angle
A graph of the angle throughout the movement
Joint points and the angle overlaid on the video
A record stored in the profile and comparable with earlier measurements

Interpreting the Results

Higher peak flexion reflects a deeper movement; the target depends on the client's condition and rehabilitation phase.
Side-to-side difference can be used for follow-up; a difference that narrows over time may be a sign of recovery.
Dynamic angle is influenced by strength, balance, pain and ankle mobility. It is not the same as passive range of motion.
Consistency between repetitions can give extra information about movement control.

Clinical Use Example

For a client beginning weight-bearing after meniscus repair, peak knee flexion during a squat is measured every two weeks. The difference from the uninvolved side and the trend of the angle are used as objective data to support loading decisions in the programme.