Adult-Acquired Flatfoot Deformity



Adult-Acquired Flatfoot Deformity


Elizabeth A. Cody, MD

Scott J. Ellis, MD


Dr. Cody or an immediate family member serves as a board member, owner, officer, or committee member of the American Orthopaedic Foot and Ankle Society. Dr. Ellis or an immediate family member serves as a paid consultant to or is an employee of Paragon 28 and Wright Medical Technology, Inc. and serves as a board member, owner, officer, or committee member of the American Orthopaedic Foot and Ankle Society.


This chapter is adapted from Ellington JK: Adult-Acquired Flatfoot and Posterior Tibial Tendon Dysfunction in Chou LB, ed: Orthopaedic Knowledge Update: Foot and Ankle 5. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2014, pp 167-179.





Introduction

Adult-acquired flatfoot deformity (AAFD) is a common problem. It commonly leads to progressive posterior tibial tendon dysfunction (PTTD), which usually occurs later in life and mostly in individuals with an anatomic predisposition. Pes planovalgus deformities can also develop in adults following untreated Lisfranc injuries and inflammatory arthropathies, but like congenital pes planovalgus deformities, these are distinct entities apart from AAFD. Symptoms of AAFD usually begin in the fifth and sixth decades of life and treatment is based on the severity of pain and deformity.




Classification

PTTD staging was first described in 1989,5 was later modified in 1996, and refined in 20076,7 (Tables 1 and 2). Other classification systems have been described.8,9 It is important to note that the classification system was created to describe the pathology of the PTT but is commonly used to describe progression of AAFD. The flatfoot deformity itself, as noted earlier, occurs with certain anatomic predispositions as well as ligament failure, involving far more than just the PTT.

Stage 1 PTTD is defined as tenosynovitis with retained strength (eg, the patient can still perform a single-limb heel rise). No alteration of foot alignment is noted clinically or radiographically. Stage II PTTD is characterized by progressive pes planovalgus deformity, which remains flexible, and decreased strength, demonstrated by the inability to perform a single-limb heel rise. Stage III PTTD is defined by a rigid planovalgus deformity, and stage IV involves changes to the ankle joint with deltoid laxity, resulting in ankle valgus deformity.

Patients presenting with stage I PTTD usually report medial ankle and hindfoot pain. Their foot remains flexible and they are able to perform a single-heel rise; however, a patient may have pain with repetitive rising. The tendon has normal function and length. Stage I PTTD is relatively rarely seen in clinical setting.

Most patients with AAFD who seek evaluation have stage II PTTD. Patients report progressive pain and deformity in most cases, and they are unable to perform a single-limb heel rise on the affected extremity. However, the deformity remains flexible and they usually can perform a double-limb heel rise. The hindfoot typically does not invert during heel rise in cases of PTT dysfunction. Patients may also report lateral hindfoot pain, which is usually attributable to development of subtalar arthritis and/or calcaneofibular (subfibular) impingement.10 Fibular stress fractures also can occur with severe deformity because of calcaneofibular abutment.

Stage III PPTD is characterized by a rigid deformity. The hindfoot is fixed in valgus and patients cannot perform a single-heel rise. Often, the subtalar joint is arthritic. Varying degrees of TN and calcaneocuboid arthrosis and deformity may also be present. With advanced disease, deformity may develop further down the medial column, extending to the naviculocuneiform (NC) joints and the first tarsometatarsal (TMT) joint. This can be observed on a lateral radiograph or WBCT with collapse at the NC joint and plantar gapping at the first TMT joint (Figure 1).

Stage IV PTTD is defined by involvement of the deltoid ligament (Figure 2). With prolonged AAFD, the deltoid becomes attenuated and valgus talar tilt

develops. The foot deformity may be flexible or rigid. Once AAFD has progressed to this stage, treatment becomes much more difficult. For this reason, weight-bearing anterior-posterior (AP) ankle radiographs should always be obtained in patients with AAFD to ensure ankle congruity and to assess for arthritis. Patients with ankle involvement may present with either isolated deltoid stretching or tearing, or frank arthritis in the ankle joint itself with lateral cartilage loss contributing to valgus talar tilt. The distinction between these two scenarios has important implications for surgical management.








TABLE 2 Clinical Classification System for Posterior Tibial Tendon






































































Stage


Substage


Characteristic Clinical Findings


Radiographic Findings


Treatment


I


A: Inflammatory disease


Normal anatomy, tender PTT


Normal


NSAIDs, immobilization, ice, orthoses, tenosynovectomy, treat specific systemic disease


B: Partial tear


Normal anatomy, tender PTT


Normal


Same as for substage A


C: Partial tear with mild HF valgus


Slight HF valgus, tender PTT


Slight HF valgus


Same as for substage A


II


A1: HF valgus with flexible FF varus


Flexible HF valgus, flexible FF varus ± tender PTT


HF valgus, Meary angle disrupted, calcaneal pitch lost


Orthoses, medial slide calcaneal osteotomy, Strayer or Achilles tendon lengthening, FDL transfer (if deformity corrects only with ankle PF)


A2: HF valgus with rigid FF varus


Flexible HF valgus, rigid FF varus ± tender PTT


Same as A1


Same as for substage A1, Cotton osteotomy


B: FF abduction


Same as for substages A1 and A2 with FF abduction


HF valgus, talonavicular uncovering, FF abduction


Medial slide calcaneal osteotomy, lateral column lengthening, Strayer or Achilles tendon lengthening, FDL transfer


C: Medial ray instability


Flexible HF valgus, fixed FF varus, medial column instability, first ray dorsiflexion with HF correction, sinus tarsi pain


HF valgus, first TMT joint plantar gaping


Medial slide calcaneal osteotomy, FDL transfer, Cotton osteotomy, or first TMT joint fusion


III


A: Rigid HF valgus


Rigid HF valgus, sinus tarsi pain


Decreased subtalar joint space, angle of Gissane sclerosis


Triple arthrodesis, custom AFO if not a surgical candidate


B: FF abduction


Same as for substage IIIA, FF abduction


Same as for substage IIIA, FF abduction


Triple arthrodesis with lateral column lengthening, custom AFO if not a surgical candidate


IV


A: Rigid HF valgus, flexible ankle valgus, deltoid ligament insufficiency, minimal ankle arthritis


Flexible tibiotalar valgus


Tibiotalar valgus, HF valgus


Correct HF valgus, reconstruct deltoid ligament


B: Significant ankle arthritis, with or without rigid ankle valgus


Rigid tibiotalar valgus


Tibiotalar valgus, HF valgus


Pantalar fusion, TTC fusion, or triple arthrodesis and TAR


Adapted from Bluman EM, Title CI, Myerson MS: Posterior tibial tendon rupture: A refined classification system. Foot Ankle Clin 2007;12:233-249.


Copyright 2007, with permission from Elsevier.


AFO = ankle-foot orthosis, FDL = flexor digitorum longus, FF = forefoot, HF = hindfoot, NSAIDs = nonsteroidal anti-inflammatory drugs, PF = plantar flexion, PTT = posterior tibial tendon, TAR = total ankle replacement, TMT = tarsometatarsal, TTC = tibiotalocalcaneal







FIGURE 1 Weight-bearing CT sagittal image demonstrating first tarsometatarsal plantar gapping (arrow), representing instability, as well as degenerative arthritis.






FIGURE 2 Stress radiograph demonstrating significant deltoid laxity. (Reproduced with permission from Ellington JK, Myerson MS: The use of arthrodesis to correct rigid flatfoot deformity. Instr Course Lect 2011;60:311-320.)


Clinical Presentation

Patients with AAFD typically present with medial hindfoot pain. However, in some patients, lateral foot pain predominates, and more rarely, patients will present with only ankle pain. Typically, prolonged ambulation and uneven terrain aggravate symptoms. Patients may report uneven shoe wear, with the medial aspect of the heel wearing out faster, or difficulty finding shoes that fit. Some patients report a prior injury, sometimes having heard or felt a “pop,” and many have been treated by their primary physicians for an “ankle sprain.” Some patients state that they have had a flatfoot their entire life, which has worsened. Comorbidities, particularly inflammatory conditions and diabetes mellitus, should be documented.


Feb 27, 2020 | Posted by in ORTHOPEDIC | Comments Off on Adult-Acquired Flatfoot Deformity
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