Pelvis Tilt and Hip flexion angle and their moments in Squat

[Satya Sri Mummidivarapu]

Hello all,
I did read about Pelvic Tilt and Hip Flexion Angle (Gait2354 vs. Clinical Measurements) on opensim confluence.
Q1. I have simulated squat in opensim and couldn’t match the hip flexion angles to the literature, though I got decent knee flexion and ankle angles. This has further effected my hip joint moment (I see value lesser than what I would expect) and pelvis tilt moment (large tilt moment). However, the knee flexion and ankle moment compares to the literature.

Q2. Also, how would this effect joint reaction forces at Hip (because opensim value of hip flexion angle differs from clinical values reported) and we calculate joint reaction forces from the same joint kinematics?

Pelvis Tilt and Hip flexion Angles

Pelvis Tilt and Hip flexion Moment

The literature reports Hip flexion angle of around 60-65 deg for knee flexions of 90 deg. My subject performs squat with peak knee flexion of 70 deg and I would expect at least 40 deg of hip flexion which I don’t see in my results.

Q3. I’m confused if I have to add or subtract that 12-13 degrees to my data to match it up with the literature.

Q4. What does it mean by having larger pelvis tilt moment? I have simulated squat in 0g where my pelvis tilt moment reach peaks out at 70 Nm.

Can someone let me understand this better? Thanks a bunch for your response.

Best regards
Satya