How to Diagnose Acquired Adult Flat Foot

This Clinical Practice Guideline (CPG) is based on the review of clinical literature and consensus of current clinical practice. 

What is Acquired Adult Flat Foot?

Flat feet are not usually painful, especially in children. This condition describes a painful, progressive flatfoot deformity in adults. It is due to a gradual stretching of the main ligaments that support the arch of the foot, as well a slowly worsening stretching (or attenuation) of the posterior tibial tendon.

Who gets this condition?

Adults! Women are four times as likely to get it as men. The most common age group is between 45-65. Usually, people who get this condition have had non-painful flat feet for most of their adult life. Factors such as diabetes, hypertension (high blood pressure) and obesity tend to increase the risk of getting this condition.

What are the signs and symptoms?

Most patients notice gradual worsening pain in one foot, and a gradual flattening of the arch in the affected foot. Pain is usually on the inside, due to pain in the stretching tendons and ligaments, but it is often accompanied by pain on the outside of the ankle, due to compression of the joints on this side. If the posterior tibial tendon ruptures, deformity can progress quickly, until the foot literally dislocates outward from under the ankle joint. This is not good. Really not good.

• Pain in the medial arch, and pain and swelling behind the inside of medial malleous. Pain and trigger points will also be felt in the muscle belly of the posterior tibialis.
• Burning, shooting, tingling pain may described along the course and distribution of the posterior tibialis nerve from inflammation inside the tarsal tunnel (known as tarsal tunnel syndrome).
• Pain may also develop on outside of ankle, especially as the deformity progresses, due to compression of the sinus tarsi.
• Pain and swelling is worse with walking and exercise, and usually gets worse as the day progresses.
• Patient will be unable to perform single leg heel raise on affected side (indicating dysfunction of posterior tibialis tendon).
• A characteristic development of a flat foot (arch collapse) on affected side.
• Usually occurs in 1 foot, however can be bilateral.

What tests and studies should be performed?

• Functional and biomechanical assessments for grading of deformity (send patient to us for this).
• Weightbearing xrays to assess midfoot and rearfoot joint positions (we can also refer for these studies)
• Early referral to podiatrist for prompt assessment and intervention will prevent worsening deformity and surgical invention in most cases.

Single leg heel raise- determines the integrity of the plantar midfoot ligaments and posterior tibial tendon

"Too many toes" sign. Indicates abduction of the forefoot on the rearfoot.

Video explaining how to test for tibialis posterior tendon pathology

How to grade Acquired Adult Flat Foot

What are the treatment goals of AAFF?

• Eliminate pain (Compression/ NSAIDS/ Aircast)
• Restore mobility (Rehab, Orthotics, manual therapies)
• Prevent progression of deformity (AFO bracing, footwear)

Treatment protocols

These treatment protocols are complex and require management by a podiatrist to provide treatment and review progress and modify as appropriate.

Stage I

• Temporary Immobilisation-Support
  • Unna Boot
  • High-Dye Taping
• Lace-Up brace with Figure 8 straps, favoring inversion
• Physical Therapy with modalities to reduce inflammation
• Footwear Modification
• Follow up custom functional foot orthoses

Stage II

• Temporary Support
  • Walking Boot for 1-6 weeks
• Long Term Support
• Footwear Modification
• Functional rehabilitation program 12 weeks
  • Custom Hinged Ankle-Foot Orthosis
  • Range of Motion, Eccentric strengthening, Balance Training

Stage III

• Temporary Immobilization
  • Rarely necessary
• Long Term Immobilization
  • If no severe DJD in Ankle and Hindfoot:
• Restricted Hinge AFO with Arch Suspender
  • If severe DJD in Ankle and Hindfoot:
    • Gauntlet with flexible AFO Shell

Stage IV

• Gauntlet with Solid AFO Shell

Studies on the conservative treatment of AAFF

Chao W; Wapner KL; Lee TH; Adams J; Hecht PJ: Non-operative management of posterior tibial tendon dysfunction. Foot Ankle Int. 17(12): 736 – 41, 1996. Alvarez RG; Marini A; Schmitt C; Saltzman CL: Stage I and II posterior tibial tendon dysfunction treated by a structured non-operative management protocol: an orthosis and exercise program. Foot Ankle Int. 27(1): 2 – 8, 2006.

Augustin JF; Lin SS; Berberian WS; Johnson JE: Non-operative treatment of adult acquired flat foot with the Arizona brace. Foot Ankle Clin. 8(3):491 – 502, 2003.

Johnny L. Lin, MD; John Balbas, MD; E. Greer Richardson, MD.Results of Non-Surgical Treatment of Stage II Posterior Tibial Tendon Dysfunction: A 7- to 10-Year Followup Foot & Ankle International/Vol. 29, No.8/August 2008

Krause F, Bosshard A, Lehmann O, Weber M. Shell brace for stage II posterior tibial tendon insufficiency. Foot Ankle Int 29 (11): 1095-1100, 2008.

Kulig K, Reischl SF, Pomrantz AB, Burnfield JM, Mais-Requejo S, Thordarson DB, Smith RW Nonsurgical management of posterior tibial tendon dysfunction with orthoses and resistive exercise: a randomized controlled trial. PHYS THER.2009; 89: 26-37

Nielsen MD, Dodson EE, Shadrick DL, Catanzariti AR, Mendocino RW, Malay DS. Nonoperative Care for the Treatment of Adult-acquired Flatfoot Deformity. Jour Foot Ankle Surg 50 (2011)311-314.

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