Firstly, what is a flat foot?
A flat foot, or a pes planus type foot is basically a foot that, when bearing weight has little or no arch.
The foot contains 26 bones, 30 joints and over 100 muscles tendons and ligaments, and that’s just one foot! Everyone is born with flat feet, as the arches don’t start to develop until we start learning to walk. Age six is the usual time that we should have a fairly stable arch, however, about two out of ten will maintain their flat feet into later life. And some will lose that arch due to certain medical conditions, trauma, overuse injuries, and age.
The important thing to remember is that the height of the arch will change as weight is applied. This motion is called pronation and is a critical biomechanical design feature of the foot during gait. Pronation is necessary because, as the foot flattens out during gait the bones in the instep of the foot slid apart slightly and allow the foot to become flexible. This allows for shock absorption and adaptation to terrain. People with high arches can suffer from knee, hip, and lower back issues because rigid high arch feet make poor shock absorbers, like having hammers on the end of your legs, people can hear you coming.
Back to why I have flat feet.
Firstly, certain medical conditions can cause the feet to flatten, such as rheumatoid arthritis, an inflammatory disease of the joints, which can involve the tendons, causing them to tear. This causes structural changes of the foot due to bone destruction and damage of the structures that hold it all together.
You’re also more likely to have flat feet if you have a neurological or muscular disease such as cerebral palsy, muscular dystrophy, or spina bifida. These diseases cause muscle wasting, by interfering with the neurological control. The lack of innervation to specific muscles or groups of muscles mean they are not used, so wasting occurs.
Acute injuries, such as from a fall, can tear the posterior tibial tendon or cause it to become inflamed. (The posterior tibial tendon is the main muscle that supports the arch of the foot.) The tendon can also tear due to overuse. For example, people who do high-impact sports, such as basketball, tennis, or soccer, may have tears of the tendon from repetitive use.
Then there’s the genetic factor. How many times have you heard,” I have feet just like my Mom or Dad”? “Hallux Abducto Valgus”, or bunions and other foot deformities are more likely to occur if you have flat feet, due to the stresses that excessive late mid stance pronation can cause within the structures of the foot. Proper alignment of the foot when walking, through the use of proper footwear and possibly a custom orthotic, can help to prevent some of these issues from occurring.
Obesity or a rapid increase in weight borne by the structures of the foot can cause damage to the ligaments and tendons which hold the foot together. Micro tears and stretching of these tendons can occur and may require surgical repair.
Then for women, there’s pregnancy and childbirth. The average weight gain during this time is roughly 28–40 pounds. On top of the problems of added weight as discussed, there are hormonal changes that occur.
Prior to childbirth the body releases hormones that relax the ligaments and tendons to allow for the widening of the pelvic floor without damage. These hormones, however, are systemic and effect” all” of the structures in the body including the feet. It is very common for women to have issues with their feet during this time and typically for several months after delivery, which is why, it is always advisable to pay extra care to the feet during this time, as these changes can be permanent just like a sports or overuse injury. Hormonal changes during menopause may also cause problems.
Written by Jaimie McVean, Certified Canadian Pedorthist