Current Concepts In Treating Flexible Flatfoot In Older Adolescents

Patients in their late teenage years may be more ideally suited to flatfoot correction as they have reached full skeletal maturity but commonly have a very flexible flatfoot deformity. Accordingly, these authors discuss treatment in a 15-year-old patient.

There are numerous discussions about how best to treat a flexible flatfoot in either the adult or pediatric patient. However, there has been little said of the population in between the two. Specifically, older adolescents with flexible flatfoot (I often think of them as having an “almost-adult” flatfoot) are a unique patient group that is rarely discussed in the literature.

These patients are typically in their later teenage years and have a very flexible flatfoot deformity. They have little or none of the permanent adaptive changes typically found in the average aged adult and at the same time, unlike younger pediatric patients, they have already reached full skeletal maturity. This patient population appears to be the most ideal and most receptive for flatfoot correction. They are old enough for a more aggressive approach but young enough to be able to adapt to the new alignment without much difficulty. In my opinion, the best treatment for these patients is treatment in the same manner as you would treat an adult with only slight modifications.

This case presentation will take a closer look at the average “almost adult” patient with flexible flatfoot and how best to approach correction of the flatfoot deformity.

A Closer Look At The Patient Presentation

A 15-year-old female patient presents to the office with a chief complaint of bunions and pain to the medial ankle bilaterally. The patient described the area as deformed, aching and painful. She had the condition for several months and it had an insidious onset. The patient also complains of bunions bilaterally. She says ambulating and exercise make the pain worse. The patient was previously evaluated by a pediatrician and past treatments included alterations of shoe gear and activity level.

The patient’s past medical history and past surgical history are non-contributory, and there is no history of trauma or developmental problems.

The non-weightbearing biomechanical exam reveals hallux abductovalgus and a bunion deformity bilaterally. The first metatarsophalangeal joint shows evidence of (+) pain with range of motion (PROM) of the first MPJ, a dorsal medial prominence, a laterally deviated hallux, limited dorsiflexion, pain to palpation, tracking of the first MPJ with ROM, and valgus rotation of the hallux bilaterally. First MPJ range of motion dorsiflexion with a loaded first ray is mildly decreased bilaterally.

There is also + pain on palpation (POP) to the posterior tibial tendon (PTT) tendon insertion at the navicular and at the ankle bilaterally. Ankle joint dorsiflexion with the knee extended is < 90 degrees and > 90 degrees with the knee flexed. There is a forefoot varus and a tibial valgum bilaterally.

The biomechanical weightbearing examination reveals that the medial arch is moderately decreased bilaterally and moderately everted resting calcaneal stance position bilaterally. There is positive double limb heel raise (DLHR) bilaterally. The gait exam shows excessive pronation in the subtalar joint bilaterally. There is early heel off during the stance phase of gait.

Radiographic imaging demonstrates a mild bunion deformity and pes planus deformity. The weightbearing AP view revealed TNJ articulation < 50 percent, increased cuboid abduction, an increased talocalcaneal angle. On the lateral view, an increased talo-calcaneal angle decreased calcaneal inclination, increased talar declination, anterior break in the cyma line and a metatarsus primus elevatus.  

The patient tried and failed conservative treatment (night splints, strapping and custom made orthoses). We proceeded to surgical intervention four months after the initial presentation for the right foot and five months later for the left foot. The procedures included a gastrocnemius recession, an Evans calcaneal osteotomy and a first metatarsal-cuneiform arthrodesis. The patient healed from the procedures uneventfully with a successful return to normal physical activity.

Postoperative radiographic evaluation demonstrates correction of the flatfoot deformity with an increased calcaneal inclination angle to normal limits, a decreased talar declination angle to normal limits, reduction of metatarsus primus elevatus and reduction of the cuboid abduction angle and talonavicular joint realignment.

The weightbearing postoperative exam shows the calcaneus is in neutral position, forefoot is parallel to the rearfoot with the subtalar joint is in neutral position and medial arch height is now within normal limits.

Essential Treatment Insights

Treatment starts out the same for an adult with a flexible flatfoot. Initially, one would offer conservative treatment through strapping, functional orthoses and bracing (AFO and UCBL-type devices) as appropriate to the patient’s degree of deformity. If the deformity is unresponsive to conservative therapy, we proceed to surgical intervention as our remaining, viable treatment option. Generally speaking, with little need to worry about structural damage, the process to selecting appropriate procedures becomes very straightforward and almost formulaic. Looking at the level of deformity in each plane, correction is easy to attain.

A thorough clinical and radiographic evaluation is paramount to properly determine the apex of the deformity. When performing the clinical exam, weight bearing and non-weight bearing biomechanical evaluations are essential. It is important to note any areas of tenderness and reducibility of the deformity. Clinical maneuvers are especially helpful in assessing the flexibility of the deformity. Finally, gait observation and shoe wear patterns are just as important although often overlooked during the exam.

Radiographic findings typically demonstrate:

• a decreased calcaneal pitch angle,
• limited talar head coverage,
• an anterior break in the CYMA line,
• an increased calcaneocuboid angle,
• an increased talocalcaneal angle and
• an increased talo-first metatarsal angle.

It is important to remember to evaluate for any coalition.

Once you have determined the degree and severity of deformity, surgical planning becomes straightforward. The clinical and radiographic findings serve to guide our decision. As this is a triplanar deformity with only a slight degree difference in planal dominance, it makes sense to approach it in a stepwise manner. Starting proximal to distal ensures that you are properly addressing both primary and compensatory deforming forces.

Surgeons can easily address the sagittal component of the deformity via a gastrocnemius recession. The Evans calcaneal osteotomy will address both frontal and transverse planal aspects of the deformity, bringing the subtalar joint back to neutral from pronated, both reducing the calcaneal valgus and lengthening the lateral column, correcting for the forefoot abduction. Finally, one addresses the forefoot varus depending on its position with the hindfoot in neutral position. Typically, a medial column stabilizing procedure(s) (with or without a medial wedge) via either a metatarsocuneiform joint, and/or naviculocuneiform joint, and/or a talonavicular joint arthrodesis will address the instability at the medial column and bring the forefoot parallel to the corrected hindfoot.

By addressing the apex of the flatfoot deformity and relieving pathological stress of the posterior tibial tendon, this combination of the procedures redirects the loading forces in the foot, recreates stability in the medial longitudinal arch and ultimately realigns the subtalar axis. In my experience, the emphasis on correction of the bony deformity has improved outcomes and reduced failure rates. This really removes the need for any tendon transfers, be it a flexor digitorum longus tendon transfer or modified Kidner procedure.

There are three key concepts to the surgical correction.

• Remove any deforming force of the leg onto the foot.

• Ensure the rearfoot position is perpendicular to the ground. Normalize the subtalar joint axis.

• The forefoot should be parallel to the corrected rearfoot position. This prevents pronatory moments for compensation.

If one adheres to these concepts, predicable reduction of the deformity in a very sequential manner will yield consistent results.

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