Key points

Introduction

Managing those with adult flatfoot deformities can be quite challenging, and the methods and devices used are wide-ranging based on the experience of the managing physician and the experience of the provider of the orthotic devices. A thorough biomechanical assessment is paramount to provide the most successful treatment due to the wide range of pathologic abnormalities and pathomechanics that lead to this painful disorder.

Pathomechanics and biomechanical assessment

A successful outcome with this patient population directly correlates to proper patient and biomechanical assessment. Patient assessment should include any previous foot surgeries, the prior use of orthoses and other devices tried, any previous injuries contributing to their diagnosis, and any other medical conditions that may contribute to their condition as presented.

The most common alignment deficiencies seen in those with adult flatfoot deformity are forefoot varus, hypermobility of the first ray, and a congenitally or iatrogenically shortened first ray, which often presents with transfer metatarsalgia. Other alignment deviations commonly seen in this patient population are excessive calcaneal valgus with resultant subfibular impingement, peritalar subluxation, and equinus contractures noted in most (Fig. 1). In late stage II and stage III tibialis posterior tendon dysfunction patients, one may see stress fractures of the distal fibula and lateral column symptoms due to the compressive forces to the lateral articular structures of the hindfoot. Other concomitant pathologic abnormalities commonly managed with these patients are hallux limitus or rigidus, tibialis posterior tendinosis or rupture, tarsal coalition, accessory navicular, midfoot osteoarthrosis, Charcot osteoarthropathy, and even some failed or nonunions of single, double, or triple arthrodeses. Patients who have had previous ankle arthrodeses or malaligned arthrodeses will often, over time, develop a secondary flatfoot deformity due to the subtalar and midtarsal articulations becoming mobile in dorsiflexion to compensate for the loss of talocrural mobility created by the ankle fusion.

With a good diagnosis in hand, a standard biomechanical assessment can then be performed, which should include evaluation of the forefoot to hindfoot relationship to determine the degree of forefoot varus that may be contributing to their presentation of hindfoot valgus. Other important factors to determine in the biomechanical examination are the amount of calcaneal inversion or eversion to determine if the alignment is flexible or fixed, such as those with a coalition or previous fusion. The examination of hindfoot mobility will designate either correction or accommodation of the hindfoot alignment with the orthotic intervention. Another critical assessment is to determine the presence and degree of gastroc-soleus contractures. Anyone caring for this group of patients will see that the ankle contractures cause the midtarsal joints to compensate for lost ankle range of motion. The patients with contractures must have allowances for compensatory subtalar and midtarsal collapse built into their orthotic device. These patients are prone to be overcorrected when making the model for an orthosis and subsequently put the device in their closet instead of in their shoe. It is paramount to recognize that these individuals have not seen subtalar neutral for several years and will not tolerate overcorrection of the compensatory alignment deviations that occur in later stages of those with adult flatfoot disorders. One rule of thumb that has been beneficial to think of is that the more flexible the foot structure is, the more rigid the device can be, and, conversely, the more rigid the foot structure, the more accommodative the device should be. Proper and detailed diagnoses, combined with a thorough patient and biomechanical assessment, will enhance any lower extremity practitioner’s outcomes and, more importantly, provide pain relief and nonoperative options for this group.

Nonoperative management options

There are more treatment options today for those with a flatfoot disorder than ever before. Tools for managing those with flatfoot disorders often include a combination of footwear changes, footwear modifications, custom foot orthoses, and custom ankle foot orthoses (AFO). It may be necessary to use one or more of these conservative tools for successful management of flatfeet. Recognizing the importance of the role of footwear for this patient group is the best starting point to discussing management options with your patient.

Footwear considerations for flatfeet

Footwear alone can make a tremendous impact on better foot function and alignment, and many patients present with shoes that are inadequate to provide good support. A frank discussion with your patient about footwear is a good starting point to explain construction and characteristics in shoes that would be beneficial to them. With today’s Internet purchases of footwear increasing, it is important to recommend the flatfoot patient to have their foot measured for adequate sizing and fit. One common misconception that is often overused is to have them purchase a “running shoe,” which is often constructed using a curved last (model in which a shoe is constructed over) designed to supinate the foot. Therefore, essentially, it is an adducted shoe on a group of patients that present with significant forefoot abduction, which leads to painful corns and callusing to the lesser toes because of the abduction of the forefoot and crowding of the lesser toes in an adducted shoe shape. The narrow midfoot in running shoes also allows for the pronated midfoot to overpower the upper and get minimal midfoot support where they need it the most. With that in mind, it is better to recommend a “walking shoe” or a shoe constructed specifically for walking, which will normally have a leather, versus a fabric, upper that increases wear life of the shoe and better “molds” to the shape of the foot as the shoe breaks in. Walking shoes normally have a wider midfoot region for better arch support and, depending on the manufacturer and model types, will have multiple widths available for better fitting and for accommodating orthotic devices.

A cross-training design athletic shoe is another type of footwear construction that works well to support the flatfoot structure, is designed for lateral motion activities, and serves to provide better hindfoot control, which is optimum for this patient group.

Other valuable construction characteristics that can be suggested are to have a lace up or Velcro closure, versus a slip-on-type shoe, to adjust for the use of an orthotic device. A firm heel counter will help resist calcaneal valgus and should be found in most better-quality walking and supportive footwear.

There is a small group of patients with significant deformities who cannot be fit in commercially available athletic or comfort footwear and who will need to be fit with custom-made shoes. Particularly, custom shoes may be better suited for the flatfoot patient with compromised sensation secondary to diabetic or peripheral neuropathy. Any patient who has failed quality, professionally fit footwear, will best be served in custom-made shoes.

There is greater availability of stylish yet supportive shoes to recommend to your patient, and it is wise for the managing physician to be conversant in footwear characteristics to secure a better outcome with any conservative intervention. Every person you treat for a flatfoot disorder should have their feet measured every time they purchase a new pair of shoes because of the progressive nature of this disorder. People tend to equate the quality of the shoe with the price that they paid, which is not necessarily true because an expensive poorly fit shoe can be just as detrimental as an inexpensive one. Successful management of flatfoot disorders should begin with appropriately fit and constructed footwear, which best matches the patient’s size, activity level, occupational demands, and severity of their deformity.