leg length discrepancy - true or false?

I've come across several clients with potential leg length discrepancy. True leg length discrepancy is very rare. 
From what my clients tell me, some therapists use leg length discrepancy to explain lower back pain and knee osteoarthritis. You may get the feeling that there is nothing you can do about it.
I would like to consider the possibility that leg length discrepancy may be due to the upper leg bone (and muscles) being habitually held (and as a result stuck) in internal rotation and the lower leg habitually held (and stuck) in external rotation and a lack of mobility in the foot. The good news is that all can be remedied.

Right leg with internal rotation of the femur and external rotation of the shin. My right leg appears longer. See the dots on the medial malleoli (internal ankle bone). If you draw a line between the two, you will notice that they are not level.

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My right leg is straighter in this photo as I have taken my upper leg back into alignment. See the dots on the medial malleoli. They are more or less on the same line.

There are several exercises that can help.
The first step is to become aware of where your parts are in relation to each other, as described above.
The second step is to avoid rushing to make changes and forcing your leg in one position or another! 
There is a lot involved before your leg can relax back into its natural alignment.
You need to check your alignment and range of movement, lying down, then weight-bearing : at the hip, at the pelvis, at the knee, at the ankle and at the forefoot. See where you are lacking in mobility and where you have excessive mobility (hypermobility of joints, i.e. hyperlaxity of ligaments). Start to introduce more movement and more stability exactly as needed. Not randomly. This is where learning about skeletal alignment comes in handy.

Learn to Stand Better and Relax Better for starters!