The biomechanics of this process in the foot is referred Bio Fungus Nuker to as pronation which is a fancy term for the flattening of the foot. As the arches fall over the years it causes the foot to flatten. This flattening can cause plantar fasciitis, heel spurs, neuromas, and ankle injuries. When the foot flattens it sets off a kinetic chain through the leg and the low back.
First as the foot flattens it causes the tibia in the lower leg to rotate. This rotation can lead to shin splints, stress fractures of the tibia, and puts rotational stress on the knee which can cause ligament tears, arthritis, and generalized knee pain. The next step up the kinetic chain is the drop in the hip and an inferior tilt to the sacrum on side of foot pronation.
This can cause hip arthritis, bursitis, and tendinitis and most common of all, low back pain. The sacrum is the base of the spine so when it leans to one side it causes the spine to lean just as in the skyscraper analogy. This puts stress and pressure on the spine and can lead to disc injuries, spinal arthritis, sciatica, and generalized low back pain. In severe chronic cases it can even lead to a curving of the spine called scoliosis. We can have all these issues because of improper alignment of the feet.