The practitioner’s objective in treating flexible flatfoot is to realign the foot and eliminate pain. Multiple nonsurgical therapeutic options are available, but if those are unsuccessful, surgical interventions can be effective.
by Neal M. Blitz, DPM, FACFAS, and Pawel Hanulewicz, MD
Flexible pes planovalgus (flatfoot) is a common condition that should be treated when it is associated with pain.1 A flatfoot in its simplest terms is defined as collapsing of the foot, resulting in loss of arch height. Flexible flatfoot differs from rigid flatfoot in that a rigid flatfoot is permanently fixed in the flat position. A flexible flatfoot is only made flat when weight is put onto the foot during standing or walking. It is important to differentiate the two forms of flatfoot (flexible vs rigid) because the management of the conditions is markedly different. Flexible flatfoot, in general, is considered to be a less severe condition. However, flexible flatfoot can be a very serious problem. The focus of this article is to identify the key features of flexible flatfoot, describe conservative treatment options, and highlight the common surgical procedures that are used to correct a flexible flatfoot.
Flatfeet may occur from childhood or develop with age. Flatfeet are very common in children and adolescents, and there is a common perception among parents and physicians that treatment should be instituted simply because the foot is ‘abnormally’ flat.2,3 A flexible flatfoot in the pediatric and adolescent patient is different than a flexible flatfoot in the adult. The physiologic flatfoot is the foot that is flat for no identifiable reason, and may be flat without ever producing pain. Some causes of flexible flatfoot include skew foot, trauma resulting in arthrosis, and bone and joint malformations. Ligamentous laxity and hypermobility (loose joints) are often associated with flatfoot. A tightness or contracture of the gastrocnemius and/or soleus muscle complex is a well known mechanism for producing a flatfoot through abnormal mechanics.4 It should also be understood that the flatfoot may be secondary to suprapedal influences, such as malalignment at the hip, knee, or ankle. End-stage flatfoot may result in collapse and subluxation of multiple joints within the foot. In severe cases, it may also result in subluxation and degeneration within the ankle. (Figure 1)
A very common cause of adult flatfoot is posterior tibial tendon dysfunction. It is well known that the posterior tibial tendon complex is the main muscular supporter of the arch. The posterior tibial tendon originates on the posterior aspect of the tibia and fibula and courses around the inner ankle to insert primarily on the navicular tuberosity, with extensions throughout the arch. The role of this tendon is to lift the arch. In some cases, posterior tibial tendon problems develop over time as a result of a flatfoot. Conversely, in other cases, injury or disease (secondary to systemic conditions) to the posterior tibial tendon may produce a flatfoot.
It is critical to understand that the flatfoot itself is never truly the source of pain. It is the secondary effects of the malpositioned foot that result in a pain cascade. Some patients may complain of pain directly under the arch where the bones have collapsed. Painful calluses may develop on the bottom of the foot in areas of increased pressure, and a common site is under the navicular tuberosity. Often, the foot will abut the ankle and cause inflammation on the outer foot within the sinus tarsi. Heel pain may develop and present as plantar fasciitis. Strain on the posterior tibial tendon may result in pain at its tendinous insertion, as well as overt tendinitis with warmth and inflammation. Bunions may occur concomitantly with flexible flatfoot and seem to be associated with ligamentous laxity and hypermobility of the medial column of the foot.
While the term “flatfoot’ is synonymous with flattening of the arch, it is really an incorrect term for describing the actual pathology of the condition. There are three components of a flatfoot: collapse of the arch, heel valgus, and forefoot abduction. Some cases will exhibit all three components of the flatfoot equally, while other cases may exhibit features of only one component – because each component occurs in a single plane, this is referred to as planal dominance of the flatfoot. The flattening of the arch is the easiest component to recognize, which is probably why the term ‘flatfoot’ is so often used to describe the condition. Heel valgus is identified when evaluating a patient from behind. Forefoot abduction is also seen best from behind, as patients may appear as if they have too many toes.
Radiographs are necessary in the evaluation of the painful flatfoot.5 Obviously most rigid causes of flatfoot (e.g., tarsal coalitions) may be immediately identified with simple radiographs, and are easily distinguished from flexible flatfoot.6,7 It is necessary to obtain standing (weightbearing) x-rays when evaluating a flatfoot because there are many joints in the foot that may be responsible for the collapse and subluxation. Flexible flatfoot requires a keen eye to evaluate the position of each bony segment and the relationship of the forefoot to rearfoot, as well as the position of the foot relative to the ankle and leg. Also, arthritic joints need to be identified, as the presence of arthrosis often will dictate the surgical plan. Magnetic resonance imaging is useful when flatfoot is secondary to posterior tibial tendinopathy, as tears of this tendon may be identified.
There is a stepwise approach to conservatively managing a flexible flatfoot; some aspects are patient-driven and other aspects are practitioner-driven. Several treatment modalities are used simultaneously to achieve a clinical improvement, and it is not always clear which particular modality results in the largest therapeutic benefit. Understanding the available conservative management options will better allow the practitioner to manage patient exceptions should they begin to fail certain treatments, and to initiate the next appropriate level of treatment.
Education. Education is crucial when managing flatfoot. The better a patient understands the condition, the more proactive they may be to treating it. Adults with flatfoot have often lived with the condition and may have slowly noticed the foot collapse over a period of years, which may help them understand the importance of intervention, especially if pain develops. Children and adolescents, on the other hand, may be less resistant to intervention because they may not have any discomfort and only be seeking intervention because their parents are concerned about the flattening foot. It must be remembered that the presence of a flatfoot doesn’t necessarily indicate a pathologic process, and practitioners should illustrate this to their patients as treatment recommendations are made.
Stretching. Because a tight calf muscle (equinus – contracture of the gastrocnemius and/or soleus) has been long associated with flexible flatfoot, a stretching program is a simple intervention aimed at counteracting this foot-deforming force. Most stretching efforts are centered on stretching the more superficial calf muscle, the gastrocnemius.
Non-steroidal anti-inflammatory drugs (NSAIDs). When inflammation is associated with a painful flexible flatfoot, oral NSAIDs may be used as they are known to reduce inflammation. In particular, they should be used to manage acute episodes of inflammation. It is important to recognize that NSAIDs are not a stand-alone treatment option for flexible flatfoot and should be combined with other treatment modalities.
Shoe gear selection. It is important to educate patients on proper shoe selection for their foot condition. Because flexible flatfoot by definition is ‘flexible’, a stable shoe is necessary to support the foot during walking. In my experience, an unstable (flexible) shoe will only promote further degeneration and pain. Key features that a shoe should have include a stiff sole and a firm heel counter.8 A shoe should not easily twist when manually torqued. A shoe should mainly bend at the ball of the foot and not at the midsole; I find this aspect to be the most critical component of a shoe when considering flatfoot deformity because a shoe that is flexible at the arch puts more stress on the arch of the foot. Lastly, a shoe should have a removable insole to accommodate a more stable orthotic than is typically provided by shoe manufacturers.
Orthotics. Insoles placed inside the shoe are important conservative interventions that work by providing structural support to the flexible flatfoot.8-10 Over the counter arch supports may be tried. Custom insoles prescribed by a physician may better balance the foot. There are specific modifications that can be added to the insole to address the collapse of the arch (such as medial flanges) and eversion of the heel (such as heel posts and skives). Spot cushioning is also very useful for areas of excessive pressure related to a flatfoot.
In children, although orthotic treatment of asymptomatic flexible mild flatfoot is controversial,3 it is common to prescribe a more supportive insole when confronted with a moderate to severe flatfoot.10 The UCBL insert, for lack of a better term, ‘cups’ the heel and arch in a neutral position. It is made from an impression of the foot and in essence becomes a replica of the foot in the corrected position. A major benefit of the UBCL is that it also fits inside a tennis shoe.
Ankle foot orthoses (AFOs). These braces are used for more serious/severe cases of flatfoot and/or less mild forms of flatfoot that have not responded to treatment with insoles.11,12 An AFO is a device that supports the arch and extends upward on the ankle and lower leg to provide additional support for the foot.13 These are also fabricated from a mold of the foot and ankle. More contemporary braces combine the benefits of a custom insole with those of an AFO, which is especially useful for patients suffering from chronic posterior tibial tendon dysfunction.
Casting and immobilization. This is a last conservative treatment option for managing patients with symptomatic flexible flatfoot, and is typically most commonly indicated for patients with posterior tibial tendinitis. However, treatment of acute cases of posterior tibial tendinitis (or tendinopathy) may begin with immobilization, followed by other conservative measures such as those listed above once inflammation is resolved. Nonetheless, the purpose of casting is to remove the strain placed on the posterior tibial tendon. Ideally a short-leg nonweightbearing cast provides the most ‘rest’ to the tendon. Some patients are better managed in a walking cast and this depends on the severity of the tendinitis. An alternative is a removable CAM (controlled ankle motion) walker, which may be beneficial if concomitant physical therapy is being used.
Surgery for flexible flatfoot is geared to towards patients who have failed conservative treatment.1 The purpose of any surgical intervention is to improve the overall foot alignment and reduce or eliminate pain. A variety of surgical techniques and procedures are used to reconstruct a flatfoot, including tendon lengthening, tendon augmentation, bone supporting implants (arthroereisis device), bone cuts (osteotomies), and/or bone fusions.
There are many decisions that the surgeon must consider when planning a flatfoot reconstruction. Of course age and skeletal maturity play a key role in the decision process; if children and adolescents are still growing, this directly impacts the range of surgical procedures that could be performed. In my practice, children younger than six years old are treated without surgery, but this clearly depends on the clinical scenario. Older patients with significant deformities may be more amenable to fusion type procedures because they are no longer growing and fusion may allow for better correction than osteotomies. Adults should be evaluated for concomitant painful arthritis that may occur as direct result of the flatfoot and the chronic joint subluxations, which are often treated with fusions. Symptomatic mild to moderate flatfoot can be managed with tendon augmentations and transfers, or selective bone cuts, with or without fusion procedures. Severe flatfoot deformities may be considered for rearfoot fusions. Flatfoot must be considered on a case-by-case basis, and various factors play a role in the surgical plan. 1
Gastrocnemius recession or tendon Achilles lengthening. Surgical management of equinus is often performed with flatfoot correction surgeries.14-16 This may be performed with a gastrconemius recession or tendo Achilles lengthening, and is determined by the clinical exam.14-16 Various techniques for gastrocnemius recession exist.3,17-19 A contemporary approach involves lengthening only the muscular bound gastrocnemius aponeurosis (Gastrocnemius Intramuscular Aponeurotic Recession, or GIAR); this technique, theoretically, only weakens the gastrocnemius pull while preserving the natural anatomic insertional attachment of gastrocnemius on the soleus.19 A tendo Achilles lengthening may be performed percutaneously or open. The advantage of an open procedure is that surgeons can determine the exact amount of lengthening and adequately secure the tendon to prevent postoperative overlengthening, which can occur from patient noncompliance.
Arthroereisis implants. Arthroereisis type procedures are popular in younger patients. (Figure 2) The procedure calls for placing an implant (metallic or absorbable) into the rearfoot between the talus and calcaneus.20-23 This implant acts as a spacer that prevents and/or limits excessive pronation or collapse of the arch. Although implanting an arthroereisis device is indeed a surgical procedure, it is probably the least invasive flatfoot procedure because it does not involve the cutting of bone or tendon work. There is also a perception that the procedure is somewhat reversible, if the implant needs to be removed at a later date. As such, the procedure is popular for use in children and adolescents. It has been theorized that arthroereisis may provide support to a growing foot that will help normalize the bony anatomy with maturation.24–26 Additionally, arthroeresis procedures may be used in combination with various procedures listed below, primarily posterior tibial tendon augmentation and midfoot fusions. In these cases, the arthroesis aligns the rearfoot while other procedures align other parts of the foot.
Posterior tibial tendon augmention. Reconstruction of the posterior tibial tendon is a mainstay of flexible flatfoot reconstruction and often performed in combination with other bony procedures for mild to moderate flatfoot deformity. In some cases, the posterior tibial tendon is physically advanced onto the navicular to ‘tighten’ up the tendon and return its mechanical advantage as an arch supporting force. If a symptomatic accessory bone is located at the insertion, the accessory bone is removed and the posterior tibial tendon is reattached to the navicular tuberosity with bone anchors.27-33 When the posterior tibial tendon is degenerated, a tendon transfer may be performed using the flexor digitorum longus tendon. 1 (Figure 3)
Medializing calcaneal osteotomy. The medial calcaneal osteotomy is a staple procedure for flexible flatfoot reconstruction, and is indicated when the heel is in a valgus position.34–37 A bone cut is performed on the widest portion of the calcaneus, and then the posterior aspect of the heel is repositioned under the leg and fixated with screws. The procedure may be performed in adolescents who are skeletally immature, but in such cases the fixation is performed with pins rather than screws to avoid growth disturbances of the bone. In my experience, heel valgus greater than 8° to 10° may be better addressed with rearfoot fusions, but this is a clinical decision.
Bone grafting osteotomies. The Evans calcaneal osteotomy is a popular procedure for adolescents because it provides flatfoot correction by lengthening the lateral part of the foot (through the calcaneus) and avoids the calcaneal growth plates.38–46 The heel is lengthened with a structural bone graft and can be fixated with wires, screws or plates. Surgeons choose this procedure when the forefoot is abducted. The Cotton medial cuneiform osteotomy is mainly indicated for children and adolescents who are skeletally immature. This procedure involves inserting a structural bone graft into the instep to realign the arch.47-51
Midfoot fusions. Midfoot fusions are probably the most commonly performed procedures for flexible flatfoot reconstructions, and are indicated when the arch is collapsed. They may be performed in isolation as a stand-alone procedure, but are often combined with rearfoot procedures and tendon transfers to balance the foot. (Figures 4-5) Medial column procedures are the Lapidus arthrodesis (or Lapidus bunionectomy), and/or navicular cuneiform arthrodesis. 52-56 When instability (hypermobility) is the cause of the collapse, fusions are directed at restoring the stability of the arch. These medial column joints are non-essential joints of the foot, so fusion of these joints does not sacrifice overall foot function. 57
Rearfoot fusions. Rearfoot fusion type procedures are reserved for severe cases of flexible flatfoot deformity, as a salvage procedure when other methods of reconstruction have failed, or with arthrosis and collapse of the rearfoot. 1 In general, rearfoot fusions should be avoided in younger patients as the rearfoot fusion procedures involve essential joints of the foot, and loss of these joints may result in premature degeneration in surrounding joints, such as the ankle or midfoot. Even so, rearfoot fusions may be necessary to stabilize the foot. A rearfoot fusion may involve a subtalar joint arthrodesis, talonavicular joint arthrodesis, and/or a calcaneocuboid joint arthrodesis. Fusion of all three rearfoot joints is called a triple arthrodesis.
Symptomatic flexible flatfoot is a complex condition. Various non-surgical modalities can be used to structurally realign the foot. Surgical intervention is warranted when conservative treatment has failed. The objective of any treatment is to realign the foot and eliminate pain. Every case of flexible flatfoot must be considered on an individual basis when developing a surgical plan.
Neal M. Blitz, DPM, FACFAS, is chief of foot surgery in the department of orthopaedics at Bronx-Lebanon Hospital Center in the Bronx, NY. Pawel Hanulewicz, MD, is a clinical research fellow within the same department.
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