Let's talk a bit about LEG LENGTH DISCREPANCIES. The pictures below show a before and after shot from a single treatment using manual therapy and corrective exercise.
You might notice in the before picture, how her right hip bone (iliac crest) is "lifted" and higher than the left side. It would be tempting to explain this posture by assuming she has a leg length discrepancy - that her right leg must be longer than the left, hence "pushing" her right hip up higher.
If that were the case, we would call this a TRUE LEG LENGTH DISCREPANCY: that one or more of the bones in the leg are truly longer than those in the other leg. It would be a STRUCTURAL cause.
The vast majority of the cases we see in the clinic are not structural in nature, but rather are primarily FUNCTIONAL DISCREPANCIES: asymmetric alignment not caused so much by the length of bones, but by muscle imbalances, abnormal joint mechanics of the pelvis, and/or alignment of the feet and ankles. The good news is these are VERY TREATABLE with manual therapy and corrective exercise.
In just one treatment session using soft tissue mobilization around the pelvis and hips, joint mobilization to her lumbar spine and pelvis, and corrective exercises to better activate her hip muscles, you can see in the after shot how that right hip is no longer higher than the left. This confirms that in her case, this was a functional issue, not a true leg length difference.
Of course we all wouldn't mind being more symmetrical and balanced, but the real reason this matters is because these alignment issues lead to compensations throughout the body and directly impact how we move. This altered and inefficient movement creates abnormal stress and strain on the body, that over time can lead to degeneration and PAIN.
To summarize then: it may be that your "knee pain" never got better with past therapies because treatments only focused on the knee, instead of taking a more global assessment of the body, perhaps to find that a functional leg length discrepancy exists, which led to the abnormal stress in the knee which then caused the pain. Good manual therapy focuses on finding and treating the cause, not the symptoms. That pain is likely to keep returning if you never remove the stressor.