Original request: https://www.reddit.com/r/posturepals/comments/1bmes43/can_someone_help_me_out_here/
Associated post: https://www.reddit.com/r/posturepals/comments/1bmdszm/can_anyone_give_me_any_tips_on_what_might_be_wrong/
Sorry for taking so long to respond. Had a hackers of week.
So yes, classical set of postural defects displayed. It's been mentioned thousand times before, but happy to do it again for you. It's such common patterns, virtually all western people suffer similar issues as you do.
Let's break it down.
Green line (plumb line) is our vertical line / plane of reference. We can measure other parts of the mechanism of the body against it to be able to judge where you are at.
This line is always placed to the purple spot at the front of your ankle. It's where your tallus bone is and its also where you distribute the entire weight of your body into the arch of the foot.
Knee (blue spot above) is too far forward from theplumb line. That means that your ankles and your knees are not in full extension (which they should be when standing upright).
Let's talk torso next. Torso is defined as Pelvis (bottom torso) + Ribcage (top torso) + spine and abdominal cavity (middle torso, so everything inbetween the top and bottom).
Legs, arms, neck and Head are NOT considered to be part of the torso.
So in your case, you have what we call "shortening and narrowing" of your torso, which is the arch in your lowerback (red curve). This shortening is your single biggest issue, and if resolved, most other problems (like your scoliosis) will be taken care of automatically. Let me explain how it happens.
There is currently a rotation in your pelvis / bottom torso. It's a rotation in the direction of the blue arrow. We know the pelvis is rotating (in relation to the rest of the torso) because we can see that your iliac (anterior superior iliac spine - blue spot at your waist height) is too far forward and down of the green plumbline. That also means, that your top sacrum (the green spot) is too high up. It must be, because the iliac and the sacrum are just 2 different spots on the same object - your pelvis. In other words, you have what's referred to as APT.
Right, so keep in mind this rotation of pelvis.
Now let's talk you through the ribcage (upper torso). So ribcage is also rotating, this time however in the exact opposite direction to the pelvis - see the yellow arrow.
That means, you are pulling the top of the ribcage backwards and you are pushing the bottom of the ribcage forwards. The yellow line at your chest is your sternum. It has marked it's top and bottom with blue spots. This sternum is the front of your ribcage and it clearly shows the backward lean at it's top.
Your ribcage is defined by the sternum at front, and by your spine at the back (that is the top straight bit of the red curve). It should be pretty obvious how it's turning.
Ok, so we now have 2 massive objects of the mechanism rotating in directly opposing ways. We could say that upper torso rotates "clockwise" and lower torso rotates "anticlockwise" as seen on the image. Now, the spine in between (middle torso) will simply assume it's shape based on the forces exerted from above (ribcage) and from below (pelvis). You must realise that the spine is highly articulated part of your body, with lot's of joints stacked on top of each other. It will simply bent depending on the forces applied to each end of it.
What we can also see on the image is that you are retracting your arms too far back, and the same goes for your head / neck.
To get a properly funcitoning mechanism, you would want to learn to move all these parts differently in relation to each other. Basically, you would want to bring all the blue spots (not the green spot though) on the green line. Yes, all of them!. And you would also want to completely flatten the red curve in your back.
You can probably imagine that if you would manage to revert the rotations in the upper and lower torso, the spine at the back would start getting straighter and you would also bring the blue points back on the plumb line.
From the anterior / posterior view, you can see the left /right imbalances. That's just a functional scoliosis and it's there because of the shortening in your torso. It's impossible to shorten torso without also twisting the spine. The scoliosis isn't that much of a problem, as most of it would resolve with expansion of the torso.
Notice, how you habitually place your left foot ahead of the right. This is repeated on every image you have taken, and I can assure you it will get repeated every single time you stand. Check for yourself next time you stand somewhere. You will notice the left foot forward to the right. That is where the scoliosis starts. Left foot forward, left knee forward, left iliac forward. That titlts the pelvis lateraly - left side drops down (don't get fooled by the boxershorts being the other way around. You just didn't put them on equally).
Now, what happens when you shift substantial amount of mass on the left side at the bottom? - you have to counterbalance that elswhere to maintain your equilibrium / balance. This compensation is visible on the right arm being retracted further back in relation to the torso. You can see the right scapula crest more pronounced and you can also see the right shoulder being higher to the left. That is because you retract the right arm further back, which means the clavicle is sliding higher up on the first rib.
It's always like that. Your equilibrium is an equation that always must be solved should you remain upright. So if you shift mass one way at the bottom, you must shift mass in the opposite direction at the top.
The same thing really applies on the sagital image except forward and backwards.
So this, in a nutshell, is what is going on with you.
The reason why you are like this is the relative movements of the different parts of the mechanism. These movements are commanded by you, although at the moment unconsciously. It's just your habit.
You can learn to override these habits and replace them with a deliberate movements. If you change the way these relative movements happen, you will end up with a different posture, and of course when you are doing that, you would want to choose movements that will promote proper functioning of the mechanism. It's all perfectly learnable and fixable.
It's a lot of info to digest, so feel free to read it few times over.
Inevitably, you will end up with more questions, so feel free to reach out.