Part 1 of 3
While walking in the sand on the beach, did you ever notice your foot print? Have you noticed that some foot prints on the beach are wider than others and show the width of the entire foot? That imprint would indicate a very flat foot with poor arch support. The arch of your foot should be apparent by age 6-11. However, some people are born with “congenital flat foot,” and never develop arches. Others are born with foot deformities (e.g. club feet) and are destined to develop flat feet. Still others develop normal arches but, their arches flatten as they age (acquired flat foot).
This “acquired flat foot” is often due to a combination of factors that would put additional, excessive stresses on the bones and tendons: (1) alignment issues of the foot or leg (2) repetitive stress from high impact sports (e.g. basketball, tennis, and soccer), (3) training errors (e.g. running on crowned roads), (4) obesity, (5) diabetes (6) hypertension, (7) rheumatoid arthritis, (8) age-related degenerative changes. In extreme cases, an acute, traumatic rupture of the tibialis posterior tendon (the tendon that helps support the arch) can also cause collapse of the arch of the foot.
If the bones in your foot and ankle are perfectly aligned, their ligaments, tendons, and muscles function correctly. Ligaments hold the bones in your foot and ankle in proper position, providing static support to your arch in weight bearing positions. Muscles and tendons move the bones in your foot and ankle, affording dynamic control to your arch during walking and running. However, if you have a flat foot, your arch lacks adequate static support from its ligaments and will excessively flatten (i.e. pronate) in weight bearing positions. In this case, the foot needs help to maintain the arch by relying on muscles and tendons for additional support.
The posterior tibial tendon (PTT) is the primary muscle/tendon that supports the arch as it travels diagonally across the inside of your ankle and then dives into the bottom of your foot to attach to multiple bones in your arch. This strategic trajectory places the PTT in a perfect position to support and control the arch of your foot.
The arch of the foot requires more than just the bones for support. The posterior tibialis tendon (PTT) plays a critical role and works hard to assist even in the normal arch. However, in the flat foot the PTT works overtime making it vulnerable to overuse and injury.
The location of this tendon allows it to work like a dynamic sling that contracts when needed, however, it is not designed to perform the job of a ligament. Moreover, excessive flattening (i.e. pronation) of the arch during stance phase over-stretches the PTT, and, because the arch excessively flattens, the PTT must work harder to raise (i.e. supinate) the arch during swing phase in preparation for the next stance phase. Eventually, the PTT will exhaust if made to endure this dual role for an extended period of time.
The arch of your foot changes position during the walking cycle. The walking cycle has two phases: stance and swing. Stance phase begins as your heel hits the ground and ends just as your toes lift off the ground. Swing phase starts just as your toes lift off the ground and finishes just before your heel hits the ground. Your foot and ankle “pronate” (i.e. your arch flattens) during stance phase to allow maximum contact with the ground. During swing phase, your foot and ankle “supinate” (i.e. your arch raises) to prepare your foot and ankle for the next stance phase. This “rise and fall” of the arch in your foot is the primary responsibility of the PTT. Because your PTT functions all the time while you walk, it never gets a rest and, therefore, is at great risk for injury.
Take the “wet foot test”! Pour a thin layer of water into a shallow pan. Wet the sole of your foot. Step onto a shopping bag or blank piece of heavy paper. Step off and look down. Observe the shape of your foot and match it with one of the foot types below:
If your foot appears to have a flat arch, your tibialis posterior tendon is at risk for injury.
Even if you appear to have an “arch” after the “wet foot test,” you may still be an over-pronator. Pronation is a necessary component of the stance phase because this motion allows your foot to conform to the contours of the ground and absorb shock. However, over-pronation over-stretches and over-uses your PTT, as described in the flat-foot scenario. Eventually, you may experience pain on the inside of your ankle every time your foot hits the ground. This painful condition is called tendonitis, and if not managed properly, your ligaments will become over-stretched. This is what leads to the collapse of the arch of your foot.
If you have a flat foot or are an over-pronator, your PTT is at risk for injury! Please join us next week to discuss the symptoms associated with PTT dysfunction (i.e. PTTD).
Visit your doctor regularly and listen to your body.
CONTRIBUTING AUTHOR: Janet Caputo, PT, DPT, OCS is clinical director of physical therapy at Mackarey & Mackarey Physical Therapy Consultants, LLC in downtown Scranton where she practices orthopedic and neurological physical therapy.
James Haggerty, DPM: Dr. Haggerty is a podiatrist in private practice in Dunmore, PA.
Vincent Grattolino, DPM: Dr. Grattolino is a podiatrist in private practice in Scranton, PA.
"Acquired Flat Foot." Source: Jennifer Hnatko, Mackarey & Mackarey Physical Therapy Consultants, LLC
"Wet Foot Test." Source: http://aneclecticblog.com/2008/05/why-good-shoes-matter/
NEXT MONDAY – Read Dr. Paul J. Mackarey “Health & Exercise Forum!” in the Scranton Times-Tribune. Next Week: Flat Feet – Part II of III.
This article is not intended as a substitute for medical treatment. If you have questions related to your medical condition, please contact your family physician. For further inquires related to this topic email: email@example.com
Paul J. Mackarey PT, DHSc, OCS is a Doctor in Health Sciences specializing in orthopaedic and sports physical therapy. Dr. Mackarey is in private practice in Scranton, PA. He is an associate clinical professor of medicine at The Commonwealth Medical College.