A New Approach To Adult-Acquired Flatfoot

By Douglas H. Richie Jr., DPM

Ask experienced DPMs what pathology has seen the most dramatic increase in prevalence over the last 20 years and, aside from plantar heel pain, they will tell you it is posterior tibial tendon dysfunction (PTTD). Currently, most authorities have dropped the description PTTD in favor of “adult-acquired flatfoot.” This is due to increased recognition of the fact that a rupture or attenuation of the posterior tibial tendon cannot itself lead to the deformity and disability that one sees in older adults with progressive flatfoot deformity. Significant ligamentous rupture occurs as the flatfoot deformity progresses. These ligaments include the spring ligament, the superficial deltoid ligament, the plantar fascia and the long and short plantar ligaments. Evaluating and recognizing various levels of ligamentous rupture is critical for treating the adult-acquired flatfoot (AAF). However, clinical staging of patients with AAF continues to rely on a system proposed by Johnson and Strom in 1989 before researchers recognized the role of ligamentous rupture in the pathology.1 In 1996, Myerson recognized the presence of a deltoid ligament rupture in late stage AAF and proposed adding a stage IV to the original classification when one sees valgus deformity of the ankle.2 With these things in mind, I would like to propose a revised classification system for the different stages of AAF. Building upon a previous discussion of PTTD pathomechanics, I believe this simple classification system can help facilitate appropriate decision-making when it comes to choosing conservative and surgical treatment options for AAF.3 When Patients Initially Present With AAF Prevailing opinion recognizes the presence of a preexisting flatfoot in nearly all patients with a symptomatic, progressive AAF. There is also a strong correlation with obesity, hypertension and diabetes among patients with AAF, making them poor surgical risks. The condition affects females more than males with 60 being the average age for the onset of symptoms. In the adult acquired flatfoot, symptoms have an insidious and usually unilateral onset. While patients may present with a progressive flatfoot deformity secondary to acute trauma or neuropathic conditions, for the purposes of this article, we’ll focus on the more common idiopathic, progressive and symptomatic AAF. Patients with AAF can initially present with various levels of pain, deformity and disability. Keep in mind that significant pain and edema can often obscure an accurate clinical examination. Often, immediate treatment of the acute symptoms will be necessary before you can proceed with a more thorough diagnostic work-up. In these situations, patients with AAF are treated no different than an athlete who has an acute ankle sprain. The combination of PRICE (protection, rest, ice, compression and elevation), which is commonly used for athletic injuries, is just as relevant in treating patients who have painful symptoms of AAF. For the immediate treatment of the acute symptoms of tenosynovitis, tendon rupture or ligament rupture in the patient with AAF, I recommend immobilization with a walking boot. Alternatively, one can employ an Unna Boot or wrap the foot and ankle with tape, but these options are not as protective. These measures can usually alleviate symptoms within several weeks. At this point, one may proceed to a subsequent detailed examination without the interference of significant pain or antalgic gait patterns. Pertinent Pointers On The Clinical Exam Evaluating static stance is the most critical part of examining the patient with a suspected progressive AAF deformity. In less than a minute, an experienced clinician can detect the telltale signs of a foot that has undergone attenuation or rupture of the posterior tibial tendon and/or key ligaments of the hindfoot. Since the majority of posterior tibial tendon rupture cases present unilaterally, comparing the symptomatic foot to the asymptomatic foot can give you insight into the severity of the pathology. First, evaluate the malleolar position from a dorsal view of the foot. In most cases, you will see an obvious asymmetry in which the symptomatic foot will have an noticeable internally rotated position of the malleoli, demonstrated by anterior displacement of the fibular malleolus and posterior displacement of the medial malleolus.

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