Adult acquired flatfoot

This is the clinical evidence summary written for health professionals. It is technical, and it lists the research this page was built from. You do not need to read it to understand your treatment or to make a decision about it.

Overview¶

• The exact incidence of flatfoot in children is unknown [1].
• Flatfoot is one of the most common deformities evaluated by pediatric orthopaedists [1].
• Whether flatfoot represents a true deformity is questionable [1].
• Staheli and colleagues regarded flatfeet as usual in infants, common in children, and within the normal range in adults [1].
• Flatfoot is evaluated and treated, often prophylactically, by certain nonorthopaedic branches of medicine [1].
• Children with flatfoot are referred to pediatric orthopaedists for the treatment of pain, perceived disability, and abnormal shoe wear [1].
• In flatfoot, the heel shows excessive eversion during weight bearing [1].
• In flatfoot, the forefoot is usually abducted [1].
• In flatfoot, there is a midfoot sag with lowering of the longitudinal arch [1].
• In flatfoot, the talar head and navicular tuberosity appear to be in contact with the floor and participate excessively in weight bearing [1].
• In flatfoot, the medial column of the foot appears longer than the lateral [1].
• The entire foot in flatfoot is often described as pronated [1].
• The description of the foot as pronated is misleading because the forefoot is actually supinated in relation to the hindfoot [1].
• The relationship of the forefoot to the hindfoot in flatfoot is appreciated when the hindfoot is corrected operatively or stabilized manually during physical examination [1].
• Clinicians might be tempted to use radiography as the defining diagnostic examination for flatfoot [1].
• Flatfoot has been considered a foot with measurements greater than two standard deviations from the mean [1].
• Radiographs to document the diagnosis of flatfoot are rarely obtained because flatfeet are relatively common and generally benign [1].
• The lack of radiographic documentation perpetuates the lack of a specific definition of flatfoot [1].
• A standing lateral radiograph allows measurement of the lateral talus–first metatarsal angle, or Meary angle [1].
• The Meary angle is normally 0 degrees, appearing as a straight line [1].
• In flexible flatfoot, an apex-plantarward Meary angle will be present [1].
• The normal range of the Meary angle varies with age [1].
• Spontaneous improvement in plantar sag is seen until age 8 years [1].
• The location of the sag can be determined as either talonavicular or naviculocuneiform joint [1].
• The location of the sag may suggest the cause of an abnormal measurement [1].
• A tight heel cord can produce a plantar flexed talus and talonavicular sag [1].
• The degree of plantar flexion of the talus is measured by the angle formed by the longitudinal axis of the talus and the horizontal [1].
• The normal angle for plantar flexion of the talus is 26.5 ± 5.3 degrees [1].
• The calcaneal pitch angle is formed by the axis of the calcaneus and the horizontal [1].
• A compelling reason to obtain radiographs in cases of flatfoot is to rule out causes of the deformity other than idiopathy [1].
• The differential diagnosis for flatfoot includes tarsal coalition [1].
• The differential diagnosis for flatfoot includes congenital vertical talus (convex pes valgus) [1].
• The differential diagnosis for flatfoot includes persistent talipes calcaneovalgus [1].
• The differential diagnosis for flatfoot includes an accessory navicular [1].
• The differential diagnosis for flatfoot includes various arthritic and inflammatory conditions [1].
• Most conditions in the differential diagnosis of flatfoot are diagnosed primarily from history and physical examination findings [1].
• Radiographs should be used to confirm a suspected diagnosis in the differential diagnosis of flatfoot [1].

Anatomy & Pathophysiology¶

Definition and Prevalence¶

• Adult acquired flatfoot deformity (AAFD) is characterized by collapse of the medial longitudinal arch, hindfoot valgus, and midfoot abduction related to dysfunction of the posterior tibial tendon (PTT) [7].
• Flatfoot refers to loss of the normal longitudinal arch of the medial foot [3].
• The prevalence of flatfoot has been reported to be as high as 80% in children, but decreases to 10% to 20% in adults [6].
• The prevalence of flatfoot has been shown to decrease substantially from 54% of 3-year-old children to 21% of 6-year-old children [6].
• Flatfoot is associated with younger age, male sex, ligamentous laxity, and obesity [6].
• Many cases of flatfoot are inherited, and a careful family history may uncover other persons with the condition [3].

Biomechanics and Pathophysiology¶

• The posterior tibial tendon (PTT) inverts the hindfoot, which locks the transverse tarsal joint, providing a stable platform for push-off during gait [7].
• When the PTT degenerates, the hindfoot falls into valgus, which stresses the medial static stabilizers of the ankle and foot, including the spring ligament [7].
• The navicular translates laterally because of spring ligament incompetence, resulting in medial talar head uncoverage and midfoot abduction [7].
• Progressive valgus stress through the ankle may result in deltoid ligament incompetence, talar tilt, and ankle arthritis [7].
• A gastrocnemius contracture develops as the axis of pull shifts laterally, which can further exacerbate the valgus alignment [7].
• The PTT is the primary dynamic support for the arch [13].
• The PTT fires after the foot is flat to generate heel rise and lock the transverse tarsal joint for a rigid, stable foot during push-off (toe-off) [13].
• The tibia rotates externally and the transverse tarsal locks as the PTT fires during push-off [13].
• The spring (calcaneonavicular) ligament is the primary static stabilizer of the talonavicular (TN) joint [13].
• Incompetence of the spring ligament is associated with increased flatfoot deformity [13].
• The most common site of spring ligament incompetence is the superomedial band, which originates off of the anterior-medial sustentaculum [13].
• Isolated acute rupture of the spring ligament has been reported to cause an acute deformity without PTTD [13].
• Biomechanical data has shown that the tibiospring (medial malleolus to navicular) is the most relevant ligament to decrease abduction [13].
• The gastrocnemius complex is often contracted in AAFD [13].

Etiology and Risk Factors¶

• AAFD is most commonly seen in overweight, middle-aged females [7].
• Risk factors for AAFD include obesity, diabetes, hypertension, trauma, and history of cortisone injections [7].
• Subtalar joint orientation may predispose some patients to developing AAFD [7].
• The etiology of PTTD is multifactorial and includes a zone of hypovascularity 2 to 6 cm proximal to the PTT insertion on the navicular [13].
• Overload of the arch due to activity or obesity is a factor in the etiology of PTTD [13].
• Inflammatory disorders such as rheumatoid arthritis (RA) are a factor in the etiology of PTTD [13].

Clinical Presentation and Examination¶

• Patients with AAFD present with medial ankle pain and gait dysfunction related to deformity [7].
• With progressive disease, lateral ankle pain may develop because of subfibular impingement [7].
• On examination, there is tenderness over the PTT [7].
• Standing evaluation from behind the patient demonstrates valgus alignment [7].
• If the patient is able to perform a single-limb heel rise and the hindfoot inverts as the heel elevates, the PTT remains functional and the deformity is considered flexible [7].
• If the hindfoot does not invert during a single-limb heel rise, the deformity is considered rigid [7].
• The presence of a gastrocnemius contracture is assessed with the Silfverskiold test, making sure to invert the hindfoot out of valgus during examination [7].
• Standing examination demonstrates asymmetric hindfoot valgus, depressed arch, and an abducted forefoot [9].
• The "too-many-toes sign" is observed when the foot is viewed posteriorly and it appears to have more than five toes [9].
• Pain or inability to perform single-limb heel rise indicates insufficient PTT [9].
• Lateral impaction syndrome or subfibular impingement with significant valgus of the heel, such that it abuts the fibula, may be present [9].
• Abutment of the lateral process of the talus and the calcaneus can occur in AAFD [9].
• In flexible flatfoot, the talar head may be palpable medially because of its plantarflexed position [6].
• Uncovering of the navicular and associated calluses may be present in flexible flatfoot [6].
• The hindfoot shows full passive motion with inversion and eversion in flexible flatfoot [6].
• With toe rise, the arch is restored, and the hindfoot rolls into varus to lock the transverse tarsal joints in flexible flatfoot [6].
• Many patients with flexible flatfoot are asymptomatic and undergo an orthopaedic evaluation because of parental concerns about the appearance of the foot [6].
• Patients who are symptomatic may report medial arch pain, calf pain caused by contracture, and/or lateral sinus tarsi pain caused by calcaneofibular abutment [6].

Radiographic Findings¶

• Weight-bearing radiographs of the foot and ankle are evaluated for degree of deformity and degenerative changes [7].
• Arch collapse is quantified by measuring Meary’s angle on the lateral view [7].
• Percentage uncoverage of the talar head on the AP foot radiograph is measured to assess deformity [7].
• A hindfoot alignment radiograph may be useful to measure hindfoot moment arm, which can predict the amount of intraoperative deformity correction required [7].
• Ankle radiographs should always be performed to assess for valgus talar tilt [7].
• MRI may demonstrate degeneration in the PTT and spring ligament injury [7].
• Pes planus is indicated by a negative lateral talar–first metatarsal angle (Meary angle) [9].
• Forefoot abduction is indicated by TN uncoverage on radiographs [9].
• Standing radiographs disclose loss of the normal medial longitudinal arch and may show mild lateral subluxation of the talonavicular joint [3].
• In severe chronic cases, degenerative talonavicular spurring may be present on standing radiographs [3].
• On the AP view, the talar head may appear uncovered, and the amount of talonavicular coverage has been shown to be related to the onset of symptoms [6].
• On lateral radiographs, the talar declination angle is increased, as is the Meary angle (the angle between the first metatarsal and the axis of the talus) [6].
• Decreased calcaneal pitch may be observed in patients with contracture of the Achilles tendon [6].
• A talar–first metatarsal angle greater than 4 degrees signifies pes planus [11].
• The normal calcaneal pitch angle is between 17 and 32 degrees [11].
• Arch height loss is documented by a decrease in the calcaneal pitch angle [11].
• A loss of medial cuneiform–floor height is also indicative of loss of arch height [11].

Classification¶

• The most common classification system for AAFD is based on the degree of deformity [7].
• Stage I is tendinopathy of the posterior tibial tendon in the absence of significant deformity [7].
• Stage II is characterized by a flexible deformity with talar head uncoverage seen on the weight-bearing AP foot radiograph [7].
• Talar head uncoverage of greater than 30% differentiates between a stage IIa and IIb deformity [7].
• Stage III is a rigid deformity due to arthritis in the hindfoot [7].
• Stage IV indicates ankle joint involvement [7].
• Stage IIA is defined by hindfoot valgus without significant forefoot abduction (<40% uncovering of the talus) [11].
• Stage IIB is defined by forefoot abduction (>40% uncovering of the talus) in addition to hindfoot valgus [11].
• Stage IIC is defined by fixed forefoot supination/varus (first ray is elevated after correction of the hindfoot to neutral) in addition to hindfoot valgus [11].
• Stage III is defined by a fixed/rigid pes planovalgus deformity [11].
• Stage IV is defined by incompetence of the deltoid ligament; standing AP ankle radiograph demonstrates lateral talar tilt (valgus) or ankle arthritis [11].

Classification¶

• Stage I AAFD is defined as posterior tibial tendinopathy in the absence of significant deformity [7].
• Stage II AAFD is characterized by a flexible deformity with talar head uncoverage seen on the weight-bearing AP foot radiograph [7].
• Stage IIa AAFD is defined as a flexible deformity with less than 30% talonavicular (TN) uncoverage on weight-bearing AP foot radiograph [7].
• Stage IIb AAFD is defined as a flexible deformity with greater than 30% talonavicular (TN) uncoverage on weight-bearing AP foot radiograph [7].
• Stage III AAFD is characterized by a rigid deformity due to arthritis in the hindfoot [7].
• Stage III AAFD is defined by the absence of hindfoot inversion with single-limb heel rise and a deformity that is not passively correctable [7].
• Stage IV AAFD indicates ankle joint involvement [7].
• Stage IV AAFD is defined by talar tilt and/or valgus ankle arthritis due to long-standing foot deformity [7].
• If the patient can perform a single-limb heel rise and the hindfoot inverts as the heel elevates, the PTT remains functional and the deformity is considered flexible [7].

Clinical Presentation¶

General Characteristics and Epidemiology¶

Patient Symptoms¶

• Patients complain of medial ankle/foot pain early, progressive loss of arch, and lateral ankle pain late due to subfibular impingement [9].

Physical Examination¶

• Standing evaluation from behind the patient demonstrates valgus alignment in AAFD [7].
• On examination, there is tenderness over the posterior tibial tendon (PTT) in AAFD [7].
• The "too-many-toes sign" is observed when the foot is viewed posteriorly and appears to have more than five toes [9].
• Pain or inability to perform a single-limb heel rise indicates insufficient posterior tibial tendon (PTT) function [9].
• Whether the deformity is flexible (passively correctable to a plantigrade foot) or fixed (rigid deformity that is not passively correctable) must be determined [9].
• The presence of a gastrocnemius contracture is assessed with the Silfverskiöld test, making sure to invert the hindfoot out of valgus during examination [7].

Imaging¶

• Weight-bearing radiographs of the foot and ankle are evaluated for degree of deformity and degenerative changes in AAFD [7].
• Percentage uncoverage of the talar head on the AP foot radiograph is measured to evaluate deformity [7].
• MRI may demonstrate degeneration in the PTT and spring ligament injury, but it is not a requisite preoperative study in the presence of significant deformity [7].
• Pes planus is indicated by a negative lateral talar–first metatarsal angle (Meary angle) on radiographs [9].
• Forefoot abduction is indicated by talonavicular (TN) uncoverage on radiographs [9].

Classification¶

• Stage I AAFD is defined as posterior tibial tendinopathy with minimal underlying deformity [7].
• Stage III AAFD is a rigid deformity due to arthritis in the hindfoot [7].

Investigations¶

Clinical Examination¶

• The single-limb heel rise test assesses posterior tibial tendon (PTT) function; if the hindfoot inverts as the heel elevates, the deformity is considered flexible [7].
• The Silfverskiold test is used to assess for gastrocnemius contracture, requiring the hindfoot to be inverted out of valgus during examination [7].
• Physical determination of flatfoot flexibility involves observing if a normal arch and varus heel appear by muscle action when the patient stands on tiptoe [3].
• In flexible flatfoot, the longitudinal arch reconstitutes when the patient walks on toes or when the foot is in a non-weight-bearing position [2].
• Stiffness or peroneal muscle spasm during passive inversion and eversion of the subtalar joint suggests the presence of tarsal coalition or inflammatory arthritis [2].
• If the hindfoot stays in valgus during examination, tarsal coalition may be present [2].

Radiographic Imaging¶

• Weight-bearing radiographs of the foot and ankle are evaluated to determine the degree of deformity and degenerative changes in adult acquired flatfoot deformity (AAFD) [7].
• Arch collapse is quantified by measuring Meary’s angle on the lateral weight-bearing radiograph [7].
• The percentage of talar head uncoverage is measured on the anteroposterior (AP) weight-bearing foot radiograph [7].
• A hindfoot alignment radiograph may be used to measure the hindfoot moment arm, which can predict the amount of intraoperative deformity correction required [7].
• Ankle radiographs should be performed to assess for valgus talar tilt [7].
• An abnormal Meary’s angle is defined as 17° in the context of AAFD, whereas the normal range is zero to 10° [7].
• Normal talar head uncoverage is defined as zero to 30% [7].
• Loss of medial cuneiform–floor height is indicative of loss of arch height [11].
• Standing radiographs may show mild lateral subluxation of the talonavicular joint in flatfoot [3].
• In severe chronic cases of flatfoot, degenerative talonavicular spurring may be present on standing radiographs [3].
• The location of the sag (talonavicular or naviculocuneiform joint) can be determined on radiographs and may suggest the cause of the abnormal measurement [1].
• The degree of plantar flexion of the talus is measured as the angle formed by the longitudinal axis of the talus and the horizontal, with a normal value of 26.5 ± 5.3 degrees [1].
• Radiographs are used to rule out causes of flatfoot other than idiopathy, including tarsal coalition, congenital vertical talus, persistent talipes calcaneovalgus, accessory navicular, and arthritic or inflammatory conditions [1].

Advanced Imaging¶

• MRI is not a requisite preoperative study in the presence of significant deformity [7].
• Computed tomography (CT) scans are used for diagnostics in tarsal coalition [14].
• A C-sign or dorsal talar beaking on x-ray may indicate middle facet coalition [14].
• An elongated anterior process of the calcaneus on the lateral radiograph may indicate calcaneonavicular coalition [14].

Treatment¶

Non-Operative¶

• Symptomatic treatment with shoe modifications, arch supports, and plantar inserts is appropriate for flatfoot [3].
• No long-term nonsurgical treatment can alter the anatomic features of flatfoot [3].
• Nonsurgical measures are the initial treatment choice for flexible flatfoot [6].
• A study of 580 preschool-aged children with flexible flatfoot demonstrated complete resolution in 38% after 1 year [6].
• No high-level studies support the treatment of patients with asymptomatic flexible flatfoot [6].
• A navicular pad, medial arch support, or a University of California Biomechanics Laboratory orthotic may help with symptoms in patients with arch pain but will not correct the deformity or prevent progression in asymptomatic patients [6].
• Patients with contractures of the Achilles tendon or gastrocnemius muscle should begin a stretching program to decrease associated calf pain [6].
• Most flexible flatfeet in children resolve spontaneously with no residual adverse effects as the child ages [2].
• Surgery is rarely indicated to treat flexible flatfoot deformity of childhood [2].

Operative¶

• Posterior tibial advancement, subtalar joint elevation or fusion, and elongation osteotomy of the lateral calcaneal neck are surgical options for flatfoot [3].
• Surgical options for flatfoot may not provide reproducible, predictable resolution of the problem [3].
• In patients with flexible flatfoot in whom prolonged nonsurgical measures fail, consideration can be given to lateral column lengthening through a calcaneal lengthening osteotomy or a combined calcaneal-cuboid-cuneiform osteotomy [6].
• Gastrocnemius recession may be simultaneously considered to manage the associated equinus deformity in patients undergoing surgical intervention for flexible flatfoot [6].
• Any surgical intervention for flexible flatfoot needs to be carefully planned to correct all aspects of the deformity [6].

Complications¶

• The differential diagnosis for flatfoot includes bony abnormalities such as tarsal coalition, congenital vertical talus (convex pes valgus), persistent talipes calcaneovalgus, and accessory navicular [1].
• In adolescents or preadolescents, nonspecific foot, ankle, or lower leg pain may be caused by tarsal coalition [2].
• Pain that is not related to exercise in a child with flatfoot may be caused by inflammatory arthritis, infection, or rarely a bone lesion [2].
• Tarsal joints are a common location for juvenile arthritis [2].
• A tight heel cord can lead to flatfoot because of compensatory midfoot breakdown [2].
• Causes of a tight heel cord include static encephalopathy, tethered cord or other intrathecal anomaly, and idiopathic factors [2].
• Congenital vertical talus is characterized by a fixed flattening of the longitudinal arch, tight heel cord, variable degree of pain, and usually a palpable dorsolateral dislocation of the navicular on the talus [2].
• Classic symptomatic tarsal coalition is characterized by fixed flattening of the longitudinal arch, fixed hindfoot valgus, and nonspecific or exercise-induced pain [2].
• During rapid passive inversion of the subtalar joint in a patient with tarsal coalition, the patient may experience peroneal muscle spasm [2].
• Patients with tarsal coalition typically present between the ages of 8 years and adolescence [2].
• During gait, patients with tarsal coalition have an externally rotated, inflexible foot [2].

Recovery¶

Natural History and Prognosis¶

• In a 2013 study of 580 preschool-aged children with flexible flatfoot, complete resolution occurred in 38% after 1 year [6].
• The prevalence of flatfoot decreases from 54% in 3-year-old children to 21% in 6-year-old children [6].
• Spontaneous improvement in plantar sag is observed until age 8 years [1].
• No long-term treatment can alter the anatomic features of the disorder [3].
• Arch supports, medial arch support, or orthotics will not correct the deformity or prevent progression in patients who are asymptomatic [6].

Post-operative Outcomes and Complications¶

• Surgical options including posterior tibial advancement, subtalar joint elevation or fusion, and elongation osteotomy of the lateral calcaneal neck may not provide reproducible, predictable resolution of the problem [3].
• Gait abnormalities have been documented following resection of talocalcaneal coalition [4].
• Arthrofibrosis involving the middle facet of the talocalcaneal joint has been reported in children and adolescents [4].
• Talonavicular coalition has been reported following avascular necrosis of the tarsal navicular [4].

References¶

[1] Tachdjian S Pediatric Orthopaedics From The Texas Scottish Rite Hospital For Children E Book. Plate 15.3 Kramer/Barmada Osteotomy of the Base of the Femoral Neck for Slipped Capital Femoral Epiphysis > Flexible Flatfoot (Pes Planovalgus) > Definition.

[2] Tachdjian S Pediatric Orthopaedics From The Texas Scottish Rite Hospital For Children E Book. The Focused Examination > Flatfoot.

[3] A Lange Medical Book Current Diagnosis Treatment In Orthopedics Fifth Edition. 10Pediatric Orthopedic Surgery > 5. Pes Planus (Flatfoot).

[4] Campbell S Operative Orthopaedics 4 Volume Set. MULTIPLE Z-PLASTY RELEASE OF A CONGENITAL RING > TARSAL COALITION/SPASTIC FLATFOOT.

[6] Orthopaedic Knowledge Update. Congenital Disorders of the Foot* > Flexible Flatfoot.

[7] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. Foot and Ankle Reconstruction > Adult Acquired Flatfoot Deformity.

[9] Miller S Review Of Orthopaedics. SECTION 16 PATELLAR TRACKING IN TOTAL KNEE ARTHROPLASTY > PES PLANUS (FLATFOOT DEFORMITY) > 10. Diagnosis.

[11] Miller S Review Of Orthopaedics. SECTION 16 PATELLAR TRACKING IN TOTAL KNEE ARTHROPLASTY > PES PLANUS (FLATFOOT DEFORMITY) > 11. Treatment—based on stage of the deformity.

[13] Miller S Review Of Orthopaedics. SECTION 16 PATELLAR TRACKING IN TOTAL KNEE ARTHROPLASTY > PES PLANUS (FLATFOOT DEFORMITY).

[14] Miller S Review Of Orthopaedics. PES PLANUS (FLATFOOT DEFORMITY).