Is it surprising that sailors have sore knees of lower backs when they stand so much of their time in unsupportive shoes, with little awareness of their biomechanics and the importance of ankle strength and arch support, and how this effects the knees and lower bak and even the upper back and shoulders, well why stop there – the neck and head. The feet are the foundations of the body and so all aggravation can come from shoes, or it can come from better gluteus recruitment and correct standing. Why do we spend money on corrective therapists when learning to stand properly and walk properly and wear decent shoes would solve a whole lot of issues. Shoes like flip flops to not encourage good foot posture because the feet slip around in the shoe and so one walks with toes turned out to keep the shoes on the feet. One does not bend the toe joint fully because the shoe falls off so the main ligament in the foot – the spring ligament is never activated!
You can see in these pictures the collapse of the ankle in the left foot – how the foot rolls in. It is not necessary to fill the gap with orthotics, but it is necessary to work on posture and correct the inward ankle roll, though awareness and exercise.