A Guide To Orthotic Therapy For Adult-Acquired Flatfoot

Author(s): 
Paul R. Scherer, DPM

   The inability of the foot in stage III to reach 90 degrees with the leg poses, in most patients, a unique challenge. Often, arthritic lipping and ankle joint degeneration affecting the anterior talocrural joint produce an osseous equinus. The laboratory fabricating the brace must know that the foot does not reach the 90 degrees standard and should accommodate for this in the cast correction.

   The resulting gauntlet brace for this equinus patient with adult-acquired flatfoot will be slightly plantarflexed and one must accommodate this deficiency by adding a lift in the shoe or tilt on the sole of the shoe. Allowing the patient with an equinus deformity to remain plantarflexed without raising the heel with extra material to support the heel will cause the anterior aspect of the leg to experience great pressure against the front of the brace at midstance as the tibia attempts to pass over the foot. Making the brace more rigid and confining to relieve this pressure redirects the sagittal plane motion requirement proximally and may produce a genu recurvatum.

   Since the gauntlet-type brace immobilizes the ankle, subtalar and midtarsal joint, it prevents motion in the sagittal, frontal and transverse planes. This is all beneficial for reducing symptoms but the patient must find an alternative to sagittal plane motion in order to ambulate.

   Rather than transfer this sagittal plane motion to the knee, which accepts it poorly, one can transfer motion to the shoe-ground interface with the use of a midsole rocker. A pedorthist who is familiar with rocker placement can easily add this rocker to most shoes. The ideal placement is a 60/40 rocker. Many extra-depth shoes are manufactured with this rocker sole.

Orthotic Therapy Recommendations For Stage III AAF

• Semi-weightbearing negative cast on foam with the foot at 90 degrees to the leg or fully dorsiflexed at the ankle. The deep foam board compresses the plaster or STS sock into the arch and snugly around the heel, producing a more accurate and comfortable brace.
• A heel cutout in the polypropylene shell produces a more comfortable design, especially for older patients.
• The brace height should be at least 18 cm from the floor for a 150 cm tall patient and 23 cm for a 180 cm tall patient. One would measure this from the floor to the collar of the brace.
• A fabrication laboratory that requests the circumference of the patient’s leg, midfoot and malleoli to ensure a total contact custom device is provided for your patient.
• A lace closure with two top Velcro straps. This allows ease of entry and exit of the foot, and contributes significantly to patient acceptance.

In Conclusion

The non-surgical treatment of adult-acquired flatfoot requires a firm understanding of the pathomechanics of this disorder. It is not simply a function of tibialis posterior dysfunction. Successful treatment is dependent on accurate staging of the disorder, utilizing all tests, observations and examinations. The effective treatment intervention is different for each stage and utilization of inappropriate treatment for a particular stage is doomed to failure.

   The appropriate staging and bracing application for stages I, II and III of adult-acquired flatfoot can restore mobility, dramatically reduce symptoms and slow the progression of a severely disabling disorder.

   Dr. Scherer is a Clinical Professor within the College of Podiatric Medicine at the Western University of Health Sciences in Pomona, Calif. He is also the CEO of ProLab Orthotics/USA. Dr. Scherer is the author of the book “Recent Advances In Orthotic Therapy.”

References

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