True, as long as the pelvis is in a position for you to do the mobs on, that is what counts. They could have their upper body resting on a chair and their knees on the ground. Keeping the hips at a 90 degree angle will allow you to perform the mobs on the sacrum and ilium/ischium.
Can you do this with patient standing and elbows on the table? Some people may not tolerate quadruped well due to wrist or knee issues.
True, as long as the pelvis is in a position for you to do the mobs on, that is what counts. They could have their upper body resting on a chair and their knees on the ground. Keeping the hips at a 90 degree angle will allow you to perform the mobs on the sacrum and ilium/ischium.