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Adult acquired flatfoot

40 citationsUpdated Oct 2026
Illustration: foot

For patients: a plain-language version of this topic is available. See the patient guide.

Overview

Adult acquired flatfoot deformity (AAFD) is a progressive condition where treatment depends on the stage of posterior tibial tendon dysfunction [9]. While commonly managed initially with nonsurgical methods for pain resolution [11], surgical intervention is reserved for patients with persistent pain or functional limitations [11]. Prompt, aggressive nonsurgical management is critical; however, patients who fail this conservative approach should strongly consider surgical correction to prevent worsening of the deformity [7]. In adolescents, rigid flatfoot deformities present a less predictable clinical course associated with various underlying causes, making etiological investigation essential for proper management [1].

Surgical indications for rigid flatfoot are strict, requiring the failure of prolonged nonsurgical attempts to relieve pain [4]. Osteotomies combined with supplemental soft-tissue procedures represent the best proven approach for managing rigid deformities [4]. For flexible flatfoot, less severe cases may be appropriately treated with a combined medializing calcaneal osteotomy and flexor digitorum longus transfer [6], whereas severe acquired flexible flatfoot might require an additional procedure for adequate correction beyond these two interventions [6]. Both Evans and Hintermann procedures demonstrate good corrective ability for AAFD [16], and double calcaneal osteotomy provides symptomatic relief and patient satisfaction in flatfoot correction [22].

The primary goals of surgical reconstruction are the relief of pain and the restoration of function, which account for satisfactory outcomes in complex reconstruction of severe pes planovalgus deformity [23]. In most patients, calcaneal osteotomy and tendon sling yield a cosmetically acceptable foot with good function [10]. While tendon transfer does not create a normal medial part of the arch in most patients with posterior tibial tendon rupture [8], the method arrests the progression of the flat-foot deformity, relieves pain, and restores inversion power of the hind part of the foot [8]. Assessment of subluxation and incongruence of the middle facet of the subtalar joint serves as an accurate diagnostic tool for symptomatic AAFD [2], with high-resolution cone-beam CT providing measurements analogous to traditional radiographic parameters [3].

Anatomy & Pathophysiology

Definition and Epidemiology

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) [33]. This condition is most commonly seen in overweight, middle-aged females [33]. Risk factors for AAFD include obesity, diabetes, hypertension, trauma, and a history of cortisone injections [33]. Subtalar joint orientation may also predispose some patients to developing AAFD [33].

The prevalence of flatfoot has been reported to be as high as 80% in children but decreases to 10% to 20% in adults [32]. Specifically, flatfoot prevalence decreases substantially from 54% of 3-year-old children to 21% of 6-year-old children [32]. Flatfoot is associated with younger age, male sex, ligamentous laxity, and obesity [32]. Tarsal coalitions are present in 1 in 100 people and are 50% bilateral [50].

Muscular and Tendon Anatomy

The posterior tibial muscle originates on the posterior aspect of the tibia, the fibula, and the interosseous membrane [30]. The posterior tibial tendon courses posteriorly and medially around the ankle in a groove adjacent to the medial malleolus and inserts on the midfoot in the area of the navicular tuberosity [30]. The PTT has bands that attach to the plantar aspect of the cuneiforms, the second, third, and fourth metatarsals, and the sustentaculum tali [30].

The PTT inverts the hindfoot, which locks the transverse tarsal joint, providing a stable platform for push-off during gait [33]. The PTT is the primary dynamic support for the arch [50]. It fires after the foot is flat to generate heel rise and lock the transverse tarsal joint for a rigid, stable foot during push-off [50]. During this phase, the tibia rotates externally and the transverse tarsal locks as the PTT fires [50]. The gastrocnemius complex is often contracted in AAFD [50].

Ligamentous Anatomy

The spring (calcaneonavicular) ligament is the primary static stabilizer of the talonavicular joint [50]. Incompetence of the spring ligament is associated with increased flatfoot deformity [50]. The superomedial band of the spring ligament is most commonly involved in incompetence, occurring in 70% of cases, and originates off of the anterior-medial sustentaculum [50]. Biomechanical data has shown that the tibiospring ligament (medial malleolus to navicular) is the most relevant ligament to decrease abduction [50].

Pathomechanics and Etiology

When the PTT degenerates, the hindfoot falls into valgus, which stresses the medial static stabilizers of the ankle and foot, including the spring ligament [33]. The navicular translates laterally due to spring ligament incompetence, resulting in medial talar head uncoverage and midfoot abduction [33]. Progressive valgus stress through the ankle may result in deltoid ligament incompetence, talar tilt, and ankle arthritis [33]. A gastrocnemius contracture develops as the axis of pull shifts laterally, which can further exacerbate the valgus alignment [33].

The etiology of PTTD is multifactorial and includes a zone of hypovascularity 2 to 6 cm proximal to the PTT insertion on the navicular [50]. Overload of the arch due to activity or obesity is a factor in the etiology of PTTD [50]. Inflammatory disorders such as rheumatoid arthritis are a factor in the etiology of PTTD [50]. Isolated acute rupture of the spring ligament has been reported to cause an acute deformity without PTTD [50]. Neglecting the broader stabilizing role of the deltoid ligament may lead to irreversible foot sequelae, such as post-traumatic plano-valgus or plano-abductus deformities [42]. Tarsal coalitions tend to cause rigid flatfoot deformities due to failure of segmentation of mesenchymal tissue [50].

In idiopathic pes planovalgus, the main feature is exacerbation of the physiological phenomenon of uncoiling of the calcaneo-pedal unit helix with pronation (or valgus) of the calcaneus and supination of the forefoot associated with internal rotation of the talo-tibio-fibular unit [69]. Triceps surae contracture is a common concomitant of flatfoot that is associated with poorer outcomes [69]. Excessive tensile forces applied by the triceps surae result in valgus displacement of the calcaneus under the talus [69]. The main characteristic of idiopathic pes planovalgus is laxity of the subtalar and transverse talar joints, combined in some patients with excessive length of the tibialis posterior muscle [69].

Clinical Presentation and Physical Findings

Patients with AAFD present with medial ankle pain and gait dysfunction related to deformity [33]. With progressive disease, lateral ankle pain may develop because of subfibular impingement [33]. Standing examination demonstrates asymmetric hindfoot valgus, depressed arch, and an abducted forefoot [45]. The "too-many-toes sign" is observed when the foot is viewed posteriorly and appears to have more than five toes due to excessive forefoot abduction [45]. Pain or inability to perform a single-limb heel rise indicates insufficient PTT [45]. Lateral impaction syndrome or subfibular impingement may be present with significant valgus of the heel such that it abuts the fibula [45]. Abutment of the lateral process of the talus and the calcaneus can occur in AAFD [45].

In flexible flatfoot, hindfoot valgus and loss of the normal medial longitudinal arch with standing are evident [32]. The talar head may be palpable medially because of its plantarflexed position in flexible flatfoot [32]. Uncovering of the navicular and associated calluses may be present in flexible flatfoot [32]. With toe rise, the arch is restored and the hindfoot rolls into varus to lock the transverse tarsal joints in flexible flatfoot [32]. Patients with flexible flatfoot may report medial arch pain, calf pain caused by contracture, and/or lateral sinus tarsi pain caused by calcaneofibular abutment [32].

The heel shows excessive eversion during weight bearing, and the forefoot is usually abducted, producing a midfoot sag with lowering of the longitudinal arch [12]. The talar head and navicular tuberosity appear to be in contact with the floor and participate excessively in weight bearing in flatfoot [12]. The forefoot is actually supinated in relation to the hindfoot in flatfoot, a fact appreciated when the hindfoot is corrected operatively or stabilized manually [12].

Radiographic Parameters and Imaging

Pes planus is indicated by a negative lateral talar–first metatarsal angle (Meary angle) on radiographs [45]. Forefoot abduction is indicated by talonavicular (TN) uncoverage on radiographs [45]. A talar–first metatarsal angle greater than 4 degrees signifies pes planus [48]. The normal calcaneal pitch angle is between 17 and 32 degrees [48]. Arch height loss is documented by a decrease in the calcaneal pitch angle [48]. A loss of medial cuneiform–floor height is indicative of loss of arch height [48].

On the AP view of weight-bearing radiographs, the talar head may appear uncovered, and the amount of talonavicular coverage has been shown to be related to the onset of symptoms [32]. On lateral radiographs, the talar declination angle is increased in flatfoot [32]. The Meary angle is increased in flatfoot [32]. Decreased calcaneal pitch may be observed in patients with contracture of the Achilles tendon [32]. The normal Meary angle is 0 degrees (a straight line) [12]. In a flexible flatfoot, an apex-plantarward angle will be present on the Meary angle measurement [12]. The location of the sag—talonavicular or naviculocuneiform joint—can be determined by radiographs and may suggest the cause of an abnormal measurement [12]. A tight heel cord produces a plantar flexed talus and talonavicular sag [12]. The degree of plantar flexion of the talus is measured by the angle formed by the longitudinal axis of the talus and the horizontal, with a normal value of 26.5 ± 5.3 degrees [12]. The calcaneal pitch angle is formed by the axis of the calcaneus and the horizontal [12].

Radiographs are used to rule out causes of flatfoot other than idiopathy, including tarsal coalition, congenital vertical talus, persistent talipes calcaneovalgus, an accessory navicular, and various arthritic and inflammatory conditions [12]. Standing radiographs disclose loss of the normal medial longitudinal arch and may show mild lateral subluxation of the talonavicular joint [27]. In severe chronic cases of flatfoot, degenerative talonavicular spurring may be present on standing radiographs [27]. A C-sign or dorsal talar beaking on x-ray may indicate a middle facet coalition [50]. An elongated anterior process of calcaneus on the lateral radiograph may indicate a calcaneonavicular coalition [50]. An abnormal Meary’s angle of 17° is demonstrated in AAFD, with a normal range of zero to 10° [33]. Talar head uncoverage is measured on the AP foot radiograph, with a normal range of zero to 30% [33]. A hindfoot alignment radiograph may be useful to measure hindfoot moment arm, which can predict the amount of intraoperative deformity correction required [33]. An AP ankle radiograph demonstrates talar tilt, which may occur because of long-standing deformity and deltoid ligament insufficiency [33]. MRI may demonstrate degeneration in the PTT and spring ligament injury but is not a requisite preoperative study in the presence of significant deformity [33].

Classification

Stage I: AAFD is defined as posterior tibial tendinopathy with minimal underlying deformity [33]. Stage II: AAFD is characterized by a flexible deformity with talar head uncoverage seen on the weight-bearing AP foot radiograph [33]. Talar head uncoverage of greater than 30% differentiates between a stage IIa and IIb deformity [33]. Stage III: AAFD is a rigid deformity due to arthritis in the hindfoot [33]. Stage IV: AAFD indicates ankle joint involvement [33].

Stage IIA: Defined by hindfoot valgus without significant forefoot abduction (<40% uncovering of the talus) [48]. Stage IIB: Defined by forefoot abduction (>40% uncovering of the talus) in addition to hindfoot valgus [48]. Stage IIC: Defined by fixed forefoot supination/varus (first ray is elevated after correction of the hindfoot to neutral) in addition to hindfoot valgus [48]. Stage III: Defined by a fixed/rigid pes planovalgus deformity [48]. Stage IV: Defined by incompetence of the deltoid ligament, with standing AP ankle radiograph demonstrating lateral talar tilt (valgus) or ankle arthritis [48].

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 [33]. If the hindfoot does not invert during a single-limb heel rise, the deformity is considered rigid [33]. The presence of a gastrocnemius contracture is assessed with the Silfverskiold test, making sure to invert the hindfoot out of valgus during examination [33].

Classification

Johnson & Strom (adapted by Myerson): This is the most common classification system for adult acquired flatfoot deformity (AAFD), which is characterized by collapse of the medial longitudinal arch, hindfoot valgus, and midfoot abduction related to posterior tibial tendon dysfunction [33]. The system is based on the degree of deformity [33]. * Stage 1: Presents with medial pain, orthograde hindfoot, orthograde middlefoot, and a possible single heel rise [64]. * Stage 2: Presents with medial pain, flexible valgus hindfoot, orthograde or abducted middlefoot, and a weakened single heel rise [64]. * Stage 3: Presents with medial and lateral hindfoot pain, contracted valgus hindfoot, abducted middlefoot, and an impossible single heel rise [64]. * Stage 4: Presents with general hindfoot pain, contracted valgus hindfoot, abducted middlefoot, and an impossible single heel rise [64].

Other Considerations: Stage III AAFD is specifically defined as a rigid deformity due to arthritis in the hindfoot [33]. Treatment of adult acquired flatfoot deformity depends on the stage of posterior tibial tendon dysfunction [9]. Rigid flatfoot deformities in adolescents have a less predictable clinical course and are associated with various underlying causes [1].

Pediatric Muller-Weiss Disease: Classification systems for this condition include a five-stage system describing increasing deformity from minimal change to talocuneiform articulation [25], and a three-group system based on various radiographic features [25]. Neither of the proposed classification systems for pediatric Muller-Weiss Disease is useful for guiding clinical management or predicting prognosis [25].

Clinical Presentation

History and General Presentation

Patients with adult acquired flatfoot deformity (AAFD) commonly present with medial ankle pain and gait dysfunction related to the deformity [33]. Early complaints typically include medial ankle or foot pain and progressive loss of arch, while lateral ankle pain develops later due to subfibular impingement [45]. As the disease progresses, lateral ankle pain may emerge specifically from subfibular impingement [33]. In the pediatric population, flatfoot is one of the most common “deformities” evaluated, though whether it represents a true deformity is questionable [12]. Many children with flexible flatfoot are asymptomatic and undergo evaluation solely due to parental concerns about foot appearance [32]. Symptomatic patients with flexible flatfoot may report medial arch pain, calf pain caused by contracture, and/or lateral sinus tarsi pain caused by calcaneofibular abutment [32].

Congenital vertical talus is characterized by fixed flattening of the longitudinal arch, a tight heel cord, variable pain, and usually a palpable dorsolateral dislocation of the navicular on the talus [26]. Classic, symptomatic tarsal coalition presents with fixed flattening of the longitudinal arch, fixed hindfoot valgus, and nonspecific or exercise-induced pain [26]. Patients with midfoot breakdown secondary to a tight heel cord may present at any age after walking, and the longitudinal arch may or may not reconstitute when the foot is in the non–weight-bearing position [26].

Physical Examination

On examination of AAFD, tenderness is noted over the posterior tibial tendon (PTT) [33]. Standing evaluation from behind demonstrates valgus alignment [33]. Standing examination of flatfoot deformity reveals asymmetric hindfoot valgus, a depressed arch, and an abducted forefoot [45]. Pain or inability to perform a single-limb heel rise indicates insufficient PTT function [45]. The examiner must determine whether the deformity is flexible (passively correctable to a plantigrade foot) or fixed (rigid and not passively correctable) [45]. Lateral impaction syndrome or subfibular impingement may be present when significant heel valgus causes abutment against the fibula [45]. Abutment of the lateral process of the talus and the calcaneus can also occur in flatfoot deformity [45].

In flexible flatfoot, the hindfoot exhibits full passive motion with inversion and eversion [32]. With toe rise, the arch is restored, and the hindfoot rolls into varus to lock the transverse tarsal joints [32]. The talar head may be palpable medially due to its plantarflexed position, and uncovering of the navicular with associated calluses may be present [32]. The range of motion of the tibiotalar joint should be tested, and the Silfverskiöld test should be performed because flexible flatfoot is often associated with Achilles tendon or gastrocnemius contracture [32].

When assessing children, the examiner must consider age because underlying conditions are age-specific [26]. An infant may have a simple positional deformity, a medial arch fat pad obscuring the arch, a calcaneovalgus foot, or congenital rocker bottom foot (vertical talus) [26]. A young child most likely has a flexible flatfoot deformity [26]. An adolescent may have a tight heel cord with secondary midfoot breakdown or a posterior spastic flatfoot caused by tarsal coalition [26]. Pain not related to exercise in children may indicate inflammatory arthritis, infection, or, rarely, a bone lesion [26]. Nonspecific foot, ankle, or lower leg pain in adolescents or preadolescents may be caused by tarsal coalition [26].

Examination begins by observing the gait pattern to determine if it is normal, antalgic, or indicative of neuromuscular dysfunction [26]. The child should heel-walk, toe-walk, and hop on each foot to assess neurologic and musculoskeletal function [26]. If the longitudinal arch is absent when standing still, the examiner should look for arch reconstitution when the patient walks on toes [26]. With the patient standing facing forward, the examiner looks for muscle atrophy, swelling, erythema, or deformity of the lower leg [26]. The lower extremity should be checked for femorotibial valgus [26]. The foot is examined from behind to assess hindfoot valgus [26]. Reconstitution of the longitudinal arch is assessed by having the patient stand on toes [26]. The examiner notes whether the hindfoot swings from valgus to varus; if it stays in valgus, tarsal coalition may be present [26]. Passive range of motion is checked with the patient sitting to rule out a tight heel cord [26]. A tight heel cord, regardless of cause, can lead to flatfoot because of compensatory midfoot breakdown [26]. Rocking the subtalar joint into inversion and eversion may reveal stiffness or peroneal muscle spasm, suggesting tarsal coalition or possibly inflammatory arthritis [26].

The most common type of flatfoot seen by the pediatric orthopaedist is the flexible flatfoot deformity of childhood, which is typically painless [26]. In this condition, the foot has supple range of motion on examination, and the longitudinal arch readily reconstitutes during toe-walking or when the foot is in a non–weight-bearing position [26]. During rapid passive inversion of the subtalar joint, a patient with tarsal coalition may experience peroneal muscle spasm [26]. During gait, a patient with tarsal coalition has an externally rotated, inflexible foot, as if wearing or having just come out of a short-leg walking cast [26]. Patients with tarsal coalition are typically between the ages of 8 years and adolescence [26].

Physical determination of flatfoot flexibility requires careful examination, and subtalar motion is usually normal [27]. In feet exhibiting a flat arch and valgus heel while standing, examination from the posterior aspect frequently discloses a normal arch and varus heel by muscle action when the patient stands on tiptoe [27]. If signs of flexible flatfoot are not present, alternative diagnoses such as tarsal coalition should be considered [27]. The physician should look for painful plantar calluses during the physical examination of flatfoot [27].

Imaging and Diagnostic Assessment

Weight-bearing radiographs of the foot and ankle are evaluated for degree of deformity and degenerative changes in AAFD [33]. Arch collapse in AAFD is quantified by measuring Meary’s angle on the lateral view [33]. Percentage uncoverage of the talar head on the AP foot radiograph is measured to evaluate AAFD [33]. Ankle radiographs should always be performed to assess for valgus talar tilt in AAFD [33]. 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 [33].

Radiographs should be obtained only if the patient with flexible flatfoot is symptomatic [32]. Weight-bearing AP, lateral, and oblique views are used to evaluate for other potential sources of the planovalgus deformity in flexible flatfoot [32]. On the AP view of flexible flatfoot, the talar head may appear uncovered, and the amount of talonavicular coverage has been shown to be related to the onset of symptoms [32]. On lateral radiographs of flexible flatfoot, the talar declination angle is increased, as is the Meary angle [32].

Standing radiographs disclose loss of the normal medial longitudinal arch and may show mild lateral subluxation of the talonavicular joint in flatfoot [27]. A standing lateral radiograph allows measurement of the lateral talus–first metatarsal angle, or Meary angle, which is normally 0 degrees [12]. The location of the sag—talonavicular or naviculocuneiform joint—can be determined on radiographs and may suggest the cause of an abnormal measurement [12]. The degree of plantar flexion of the talus—the angle formed by the longitudinal axis of the talus and the horizontal—can be measured, with a normal value of 26.5 ± 5.3 degrees [12]. The calcaneal pitch angle, formed by the axis of the calcaneus and the horizontal, can also be measured [12].

The most compelling reason to obtain radiographs in cases of flatfoot is to rule out causes of the “deformity” other than idiopathy [12]. The differential diagnosis for flatfoot includes bony abnormalities such as tarsal coalition, congenital vertical talus (convex pes valgus), persistent talipes calcaneovalgus, an accessory navicular, and various arthritic and inflammatory conditions [12]. Most conditions in the differential diagnosis of flatfoot are diagnosed primarily from the history and physical examination findings, and radiographs should be used to confirm a suspected diagnosis [12].

It was possible to define reference values for three parameters (talometatarsal index, talo-first-metatarsal-base angle, talo-first-metatarsal angle in the lateral-view) evaluating juvenile flatfoot deformity [38]. Calcaneal pitch angle and calcaneus-fifth-metatarsal angle do not allow any statement about the positional relationship between the talus and the subtalar footplate and are less suitable to characterize the flatfoot deformity [38]. The threshold ranges for calcaneal pitch angle and calcaneus-fifth-metatarsal angle are particularly high, and AUC values are far under 0.9 [38].

Investigations

Clinical Examination

Physical examination differentiates flexible from rigid deformity and identifies specific pathologies. The single-limb heel rise test assesses posterior tibial tendon function; if the hindfoot inverts as the heel elevates, the tendon remains functional and the deformity is considered flexible [33]. Physical determination of flexibility requires examination from the posterior aspect, where a normal arch and varus heel by muscle action when standing on tiptoe indicate a flexible flatfoot [27]. If signs of a flexible flatfoot are not present during physical examination, alternative diagnoses such as tarsal coalition should be considered [27]. In children with flatfoot, reconstitution of the longitudinal arch during toe-walking or in a non-weight-bearing position indicates a flexible deformity [26]. Conversely, if the hindfoot stays in valgus during toe-walking, tarsal coalition may be present [26]. The Silfverskiold test assesses for gastrocnemius contracture, with the hindfoot inverted out of valgus during examination [33]. Stiffness or peroneal muscle spasm during passive inversion and eversion of the subtalar joint suggests the presence of tarsal coalition or inflammatory arthritis [26]. A tight heel cord can lead to flatfoot because of compensatory midfoot breakdown [26].

Radiographic Assessment

Plain radiography: Weight-bearing radiographs of the foot and ankle are evaluated for degree of deformity and degenerative changes in adult acquired flatfoot deformity [33]. Arch collapse is quantified by measuring Meary’s angle on the lateral weight-bearing radiograph [33]. The percentage of uncoverage of the talar head is measured on the anteroposterior weight-bearing foot radiograph [33]. Ankle radiographs should always be performed to assess for valgus talar tilt [33]. A talar–first metatarsal angle greater than 4 degrees on a lateral foot radiograph signifies pes planus [48]. The calcaneal pitch angle is determined on the lateral radiograph, with a normal range between 17 and 32 degrees [48]. Loss of medial cuneiform–floor height on a lateral radiograph is indicative of loss of arch height [48]. In severe chronic cases, degenerative talonavicular spurring may be present on standing radiographs [27]. 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 [12]. The degree of plantar flexion of the talus can be measured on a standing lateral radiograph, with a normal value of 26.5 ± 5.3 degrees [12]. The calcaneal pitch angle can be measured on a standing lateral radiograph as the angle formed by the axis of the calcaneus and the horizontal [12]. An elongated anterior process of the calcaneus on the lateral radiograph may indicate a calcaneonavicular coalition [50].

Other Considerations: A hindfoot alignment radiograph may be useful to measure the hindfoot moment arm, which can predict the amount of intraoperative deformity correction required [33]. Frontal tomography of the hind part of the foot is a useful method for assessing residual supination deformity of the calcaneus, which correlates well with clinical severity of equinus, varus, and adductus deformities [55].

Advanced Imaging

MRI: MRI may demonstrate degeneration in the posterior tibial tendon and spring ligament injury [33]. MRI is not a requisite preoperative study in the presence of significant deformity [33].

CT: CT scans are used in the diagnostics of flatfoot deformity, particularly for identifying tarsal coalitions [50].

Treatment

Non-Operative Management

Symptomatic treatment with shoe modifications, arch supports, and plantar inserts is appropriate for flatfoot because no long-term treatment can alter the anatomic features of the disorder [27]. In patients with flexible flatfoot and arch pain, a navicular pad, medial arch support, or a University of California Biomechanics Laboratory orthotic may help with symptoms but will not correct the deformity or prevent progression in patients who are asymptomatic [32]. Patients with contractures of the Achilles tendon or gastrocnemius muscle should begin a stretching program to decrease associated calf pain [32]. No high-level studies support the treatment of patients who are asymptomatic with flexible flatfoot [32].

Operative Management

Indications: The treatment of adult acquired flatfoot deformity depends on the stage of posterior tibial tendon dysfunction [9]. In the few patients with flexible flatfoot in whom prolonged nonsurgical measures fail, consideration can be given to lateral column lengthening [32]. Triple arthrodesis is rarely appropriate and should be performed only according to specific indications [62].

Surgical Approach / Technique: Severe flatfoot might require an additional procedure for adequate correction beyond medializing calcaneal osteotomy and flexor digitorum longus transfer [6]. Tendon transfer does not create a normal medial part of the arch in most patients, but arrests the progression of the flat-foot deformity, relieves pain, and restores inversion power of the hind part of the foot [8]. Both H-LCL and E-LCL osteotomies provide outstanding radiographic correction and significant enhancement of clinic scores in flatfoot deformity [34]. Double calcaneal osteotomy could be used to correct flatfoot deformities effectively and sustainably and provide symptomatic relief and patient satisfaction [22]. Calcaneo-stop arthroereisis resulted in significant clinical, functional, and radiographic improvement in children with symptomatic flexible flatfoot, with correction maintained at a minimum follow-up of three years [15]. The relief of pain and the restoration of function achieved through effective correction of the severe pes planovalgus deformity account for the satisfactory outcomes in complex reconstruction involving distraction arthrodesis of the calcaneocuboid joint and flexor digitorum longus transfer [23]. Posterior tibial advancement, subtalar joint elevation or fusion, and elongation osteotomy of the lateral calcaneal neck are surgical options for flatfoot, but they may not provide reproducible, predictable resolution of the problem [27]. Lateral column lengthening can be achieved either through a calcaneal lengthening osteotomy or through a combined calcaneal-cuboid-cuneiform osteotomy [32].

Adjuncts: Gastrocnemius recession may be simultaneously considered to manage the associated equinus deformity in flexible flatfoot surgery [32].

Other Considerations: For ankle osteoarthrosis, total ankle replacement demonstrates superior gait mechanics compared to arthrodesis [9]. The operative treatment showed better results compared to the nonoperative treatment in children with painful rigid flatfoot and talocalcaneal coalition [66]. In contrast to the working hypothesis, there is no evidence of progression to valgus flatfoot after tibialis posterior transfer performed to treat central foot drop [24].

Complications

Other Considerations: Tendon transfer does not create a normal medial part of the arch in most patients [8].

Recovery

Other Considerations: The evidence provided does not specify standard recovery timelines, such as weeks for light activity or months for full activity and complete recovery. Consequently, specific time ranges for these phases are omitted to avoid conflating follow-up intervals with recovery milestones.

Tendon transfer for posterior tibial tendon rupture arrests the progression of the flat-foot deformity [8], relieves pain [8], and restores inversion power of the hind part of the foot [8]. However, this procedure does not create a normal medial part of the arch in most patients [8]. In complex reconstruction, satisfactory outcomes are attributed to the relief of pain and the restoration of function achieved through effective correction of severe pes planovalgus deformity [23].

Double calcaneal osteotomy corrects flatfoot deformities effectively and sustainably [22], providing symptomatic relief and patient satisfaction [22]. For symptomatic coalition of the middle facet of the talocalcaneal joint, tendon interposition appears to be an excellent procedure after initial nonoperative treatment has failed [75].

In ambulatory patients with cerebral palsy and planovalgus foot deformity treated with calcaneal lengthening osteotomy, a noticeable tendency toward overcorrection of the deformity is highlighted [35]. This overcorrection is evidenced by increased pressure exerted on the lateral midfoot [35]. Correction from calcaneo-stop arthroereisis was maintained at a minimum follow-up of three years [15].

Key Evidence

  • [L5] Rigid flatfoot deformities in adolescents have a less predictable clinical course and are associated with various underlying causes, making it critical to investigate the etiology to recommend proper management. [1] (10.5435/jaaos-d-21-00448)
  • [L3] The assessment of the amount of subluxation and incongruence of the middle facet of the subtalar joint represents an accurate diagnostic tool for symptomatic adult acquired flatfoot deformity. [2] (10.2106/jbjs.19.00073)
  • [L2] Measurements analogous to traditional radiographic parameters of adult acquired flatfoot deformity are obtainable using high-resolution cone-beam CT. [3] (10.2106/jbjs.16.01366)
  • [L4] Indications for surgery are strict, requiring failure of prolonged nonsurgical attempts to relieve pain, and osteotomies with supplemental soft-tissue procedures are the best proven approach for management of rigid flatfoot. [4] (10.5435/jaaos-22-10-623)
  • [L4] Both flatfoot and non-flatfoot groups demonstrated statistically significant improvements in functional outcomes (VAS and AOFAS) compared to preoperative values. [5] (10.1186/s12891-026-09801-1)
  • [L5] Less severe acquired flexible flatfoot might be appropriately treated with a combined medializing calcaneal osteotomy and flexor digitorum longus transfer, while severe flatfoot might require an additional procedure for adequate correction. [6] (10.2106/jbjs.e.00045)
  • [L5] Prompt early, aggressive nonsurgical management is important, and patients in whom such treatment fails should strongly consider surgical correction to avoid worsening of the deformity. [7] (10.5435/00124635-200807000-00005)
  • [L4] Tendon transfer does not create a normal medial part of the arch in most patients, but our method arrests the progression of the flat-foot deformity, relieves pain, and restores inversion power of the hind part of the foot. [8] (10.2106/00004623-198567090-00027)
  • [L5] For ankle osteoarthrosis, total ankle replacement demonstrates superior gait mechanics compared to arthrodesis, while adult acquired flatfoot deformity treatment depends on the stage of posterior tibial tendon dysfunction. [9] (10.1302/2058-5241.1.000015)
  • [L4] In most patients, the operation yielded a cosmetically acceptable foot with good function. [10] (10.2106/00004623-198971080-00011)
  • [L5] Adult acquired flatfoot deformity (AAFD) is commonly treated with nonsurgical methods for pain resolution, while surgical interventions are reserved for patients with persistent pain or functional limitations. [11] (10.5435/jaaos-d-21-00008)
  • [L5] The prognosis for spontaneous increase in arch height and avoidance of long-term pain without treatment is excellent for children with flexible flatfoot; therefore, the most important aspect of treatment is identification of the entity to permit a change in focus from intervention to education. [13] (10.2106/00004623-199512000-00021)
  • [L4] Concomitant triple C and the modified Kidner procedure result in favorable radiographic and clinical outcomes in the treatment of severe flatfoot associated with a symptomatic accessory navicular in children and adolescents. [14] (10.1186/s13018-014-0131-2)
  • [L3] Calcaneo-stop arthroereisis resulted in significant clinical, functional, and radiographic improvement in children with symptomatic flexible flatfoot, with correction maintained at a minimum follow-up of three years. [15] (10.1007/s00264-026-07030-8)
  • [L3] Both Evans and Hintermann procedures have good corrective ability for adult acquired flatfoot deformity. [16] (10.1186/s13018-024-04584-4)
  • [L4] With additional procedures, double calcaneal osteotomy was an effective method for severe adolescent flexible flatfoot. [17] (10.1186/s13018-017-0655-3)
  • [L4] Functional outcomes are limited by preoperative range of motion and talus deformities. [18] (10.1007/s00402-018-2932-y)
  • [L4] Double calcaneal osteotomy could be used to correct flatfoot deformities effectively and sustainably and provide symptomatic relief and patient satisfaction. [22] (10.1186/s13018-024-05106-y)
  • [L4] The relief of pain and the restoration of function achieved through effective correction of the severe pes planovalgus deformity account for the satisfactory outcomes. [23] (10.2106/00004623-199911000-00006)
  • [L4] In contrast to the working hypothesis, we found no evidence of progression to valgus flatfoot after TPT transfer performed to treat central foot drop. [24] (10.1016/j.otsr.2018.11.013)
  • [L5] [25] (10.5435/jaaosglobal-d-24-00402)
  • [L5] [30] (10.5435/00124635-199903000-00004)
  • [L3] Both H-LCL and E-LCL osteotomies provide outstanding radiographic correction and significant enhancement of clinic scores in flatfoot deformity. [34] (10.1186/s12891-025-08678-w)
  • [L3] Furthermore, our findings highlight a noticeable tendency toward the overcorrection of the deformity, as evidenced by increased pressure exerted on the lateral midfoot. [35] (10.2106/jbjs.24.00394)
  • [L3] [38] (10.1186/s12891-020-03854-6)
  • [L5] Neglecting this broader stabilizing role may lead to irreversible foot sequelae, such as post-traumatic plano-valgus or plano-abductus deformities. [42] (10.1530/eor-2025-0268)
  • [L4] Frontal tomography of the hind part of the foot is a useful method for assessing residual supination deformity of the calcaneus, which correlates well with clinical severity of equinus, varus, and adductus deformities. [55] (10.2106/00004623-197456080-00004)
  • [L4] Triple arthrodesis is rarely appropriate and should be performed only according to specific indications. [62] (10.2106/00004623-199303000-00004)
  • [L4] [64] (10.1007/s00402-015-2295-6)
  • [L3] The operative treatment showed better results compared to the nonoperative treatment. [66] (10.1186/s12891-020-03213-5)
  • [L4] [69] (10.1016/j.otsr.2018.03.010)
  • [L4] On the basis of these early results, tendon interposition appears to be an excellent procedure for the treatment of a symptomatic coalition of the middle facet of the talocalcaneal joint after initial nonoperative treatment has failed. [75] (10.2106/00004623-199901000-00003)

References

[1] Evaluation and Management of Adolescents With a Stiff Flatfoot. Journal of the American Academy of Orthopaedic Surgeons. 2022. DOI: 10.5435/jaaos-d-21-00448

[2] Subluxation of the Middle Facet of the Subtalar Joint as a Marker of Peritalar Subluxation in Adult Acquired Flatfoot Deformity. Journal of Bone and Joint Surgery. 2019. DOI: 10.2106/jbjs.19.00073

[3] Flexible Adult Acquired Flatfoot Deformity. Journal of Bone and Joint Surgery. 2017. DOI: 10.2106/jbjs.16.01366

[4] Flatfoot Deformity in Children and Adolescents. Journal of the American Academy of Orthopaedic Surgeons. 2014. DOI: 10.5435/jaaos-22-10-623

[5] Effect of concomitant flatfoot on surgical outcomes following isolated talocalcaneal coalition resection in adult patients: a retrospective study. BMC Musculoskeletal Disorders. 2026. DOI: 10.1186/s12891-026-09801-1

[6] Correction of Moderate and Severe Acquired Flexible Flatfoot with Medializing Calcaneal Osteotomy and Flexor Digitorum Longus Transfer. The Journal of Bone & Joint Surgery. 2006. DOI: 10.2106/jbjs.e.00045

[7] Adult-acquired Flatfoot Deformity. Journal of the American Academy of Orthopaedic Surgeons. 2008. DOI: 10.5435/00124635-200807000-00005

[8] Rupture of the posterior tibial tendon causing flat foot. Surgical treatment.. The Journal of Bone & Joint Surgery. 1985. DOI: 10.2106/00004623-198567090-00027

[9] Hallux valgus, ankle osteoarthrosis and adult acquired flatfoot deformity: a review of three common foot and ankle pathologies and their treatments. EFORT Open Reviews. 2016. DOI: 10.1302/2058-5241.1.000015

[10] Calcaneal osteotomy and tendon sling for the management of calcaneus deformity.. The Journal of Bone & Joint Surgery. 1989. DOI: 10.2106/00004623-198971080-00011

[11] Adult Acquired Flatfoot Deformity. Journal of the American Academy of Orthopaedic Surgeons. 2022. DOI: 10.5435/jaaos-d-21-00008

[12] 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.

[13] Flexible Flatfoot and Skewfoot. The Journal of Bone & Joint Surgery. 1995. DOI: 10.2106/00004623-199512000-00021

[14] Concomitant calcaneo-cuboid-cuneiform osteotomies and the modified Kidner procedure for severe flatfoot associated with symptomatic accessory navicular in children and adolescents. Journal of Orthopaedic Surgery and Research. 2014. DOI: 10.1186/s13018-014-0131-2

[15] Evaluation of the calcaneo-stop procedure with FIT-CS for the surgical treatment of juvenile flatfoot. International Orthopaedics. 2026. DOI: 10.1007/s00264-026-07030-8

[16] Biomechanical effects of Evans versus Hintermann osteotomy for treating adult acquired flatfoot deformity: a patient-specific finite element investigation. Journal of Orthopaedic Surgery and Research. 2024. DOI: 10.1186/s13018-024-04584-4

[17] Double calcaneal osteotomy for severe adolescent flexible flatfoot reconstruction. Journal of Orthopaedic Surgery and Research. 2017. DOI: 10.1186/s13018-017-0655-3

[18] Limitation of flatfoot surgery in overcorrected clubfeet after extensive surgery. Archives of Orthopaedic and Trauma Surgery. 2018. DOI: 10.1007/s00402-018-2932-y

[22] Clinical and radiological outcomes of flexible flatfoot correction with double calcaneal osteotomy. Journal of Orthopaedic Surgery and Research. 2024. DOI: 10.1186/s13018-024-05106-y

[23] Complex Reconstruction for the Treatment of Dorsolateral Peritalar Subluxation of the Foot. Early Results After Distraction Arthrodesis of the Calcaneocuboid Joint in Conjunction with Stabilization of, and Transfer of the Flexor Digitorum Longus Tendon to, the Midfoot to Treat Acquired Pes Planovalgus in Adults. The Journal of Bone & Joint Surgery*. 1999. DOI: 10.2106/00004623-199911000-00006

[24] Tibialis posterior transfer for foot drop due to central causes: Long-term hindfoot alignment. Orthopaedics & Traumatology: Surgery & Research. 2019. DOI: 10.1016/j.otsr.2018.11.013

[25] Surgical Management of Pediatric Muller-Weiss Disease. JAAOS: Global Research and Reviews. 2025. DOI: 10.5435/jaaosglobal-d-24-00402

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

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

[30] Posterior Tibial Tendon Insufficiency: Diagnosis and Treatment. Journal of the American Academy of Orthopaedic Surgeons. 1999. DOI: 10.5435/00124635-199903000-00004

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

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

[34] Comparative effects of two calcaneal lengthening osteotomies (Hintermann vs. Evans) in stage II adult-acquired flatfoot. BMC Musculoskeletal Disorders. 2025. DOI: 10.1186/s12891-025-08678-w

[35] Outcomes of Calcaneal Lengthening Osteotomy in Ambulatory Patients with Cerebral Palsy and Planovalgus Foot Deformity. Journal of Bone and Joint Surgery. 2025. DOI: 10.2106/jbjs.24.00394

[38] Is it possible to define reference values for radiographic parameters evaluating juvenile flatfoot deformity? A case-control study. BMC Musculoskeletal Disorders. 2020. DOI: 10.1186/s12891-020-03854-6

[42] Deltoid ligament injury: thinking beyond the ankle – an expert opinion. EFORT Open Reviews. 2026. DOI: 10.1530/eor-2025-0268

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

[48] 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.

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

[55] Residual Deformity of Treated Congenital Club Foot. The Journal of Bone & Joint Surgery. 1974. DOI: 10.2106/00004623-197456080-00004

[62] Late complications of fractures of the calcaneus.. The Journal of Bone & Joint Surgery. 1993. DOI: 10.2106/00004623-199303000-00004

[64] Interference screw for fixation of FDL transfer in the treatment of adult acquired flat foot deformity stage II. Archives of Orthopaedic and Trauma Surgery. 2015. DOI: 10.1007/s00402-015-2295-6

[66] Operative versus nonoperative treatment in children with painful rigid flatfoot and talocalcaneal coalition. BMC Musculoskeletal Disorders. 2020. DOI: 10.1186/s12891-020-03213-5

[69] Surgical treatment of idiopathic pes planovalgus in paediatric patients. Orthopaedics & Traumatology: Surgery & Research. 2019. DOI: 10.1016/j.otsr.2018.03.010

[75] Interposition of the Split Flexor Hallucis Longus Tendon After Resection of a Coalition of the Middle Facet of the Talocalcaneal Joint. The Journal of Bone & Joint Surgery*. 1999. DOI: 10.2106/00004623-199901000-00003

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