Ovid: 5-Minute Orthopaedic Consult

Editors: Frassica, Frank J.; Sponseller, Paul D.; Wilckens, John H.
Title: 5-Minute Orthopaedic Consult, 2nd Edition
> Table of Contents > Flatfoot

Kris J. Alden MD, PhD
  • Flatfoot, or pes planus, is a deformity of the foot in which the normal medial longitudinal arch of the foot has been lost (14).
  • It may present as an asymptomatic
    incidental finding or as a painful condition secondary to an associated
    anatomic abnormality or pathologic condition of the foot.
  • Classification:
    • Rigid versus flexible:
      • A flexible flatfoot lacks an arch only when patient is weightbearing, not when nonweightbearing or toe-standing.
      • A rigid flatfoot lacks an arch at all times.
    • Pediatric versus adult:
      • Onset may indicate underlying potential cause.
  • Congenital flexible flatfoot after infancy:
    • Is a trait that often runs in families, although the pattern of inheritance is not known
    • Is present in ~15% of adults (5)
  • Tarsal coalition, the most common type of congenital rigid flatfoot, is inherited in an autosomal dominant pattern (6).
    • The exact overall incidence is unknown, but it is <1% (7).
  • PTT deficiency is the most common cause of acquired flatfoot in adults, although its precise incidence is not known.
  • The exact incidence of other patterns of acquired flatfeet is not known.
Risk Factors
  • For persistent congenital flexible flatfoot: Other family members with the same condition
  • For congenital rigid flatfoot secondary to tarsal coalition: Female gender and other family members with the same condition
  • For acquired flexible flatfoot secondary to PTT synovitis or rupture: Hypertension, diabetes, and a history of trauma
  • Other conditions that can lead to flatfoot:
    • Tight Achilles tendon
    • Neurologic diseases (e.g., poliomyelitis, spina bifida, myelodysplasia, NF, stroke)
    • Osteoarthritis, posttraumatic arthritis, or inflammatory arthritis
    • Charcot arthropathy secondary to diabetes or other peripheral neuropathy
  • Congenital flexible flatfoot and tarsal coalition are the result of genetic inheritance.
  • PTT dysfunction is secondary to tendon degeneration and attenuation.
  • Flatfoot deformity from Charcot neuroarthropathy is secondary to bone fragmentation, resorption, and fracture.
  • Other causes to consider: Congenital vertical talus, peroneal spastic flatfoot, and trauma (812)
Signs and Symptoms
  • Flatfoot with low or no arch
  • Pain over medial arch
  • Deformity may progress with time.
  • May be exacerbated by walking, sports, high level of activity, or traumatic event
  • Abnormal shoe wear pattern
  • The onset of deformity, family history,
    associated diseases, activity level, and history of previous trauma
    should be noted for all patients.
  • The patient or parents may complain of
    tenderness and swelling along the medial part of the foot, a diminished
    endurance in the foot, a decreased ability to participate in sports,
    and, eventually, a progressive difficulty in ambulating.
  • Increased wear on medial aspect of the shoe
  • Pediatric flatfoot deformity often is present from an early age.
  • Adult acquired flatfoot caused by
    arthritis or rupture of the PTT presents as a gradual, progressive
    aching and swelling along the medial aspect of the foot and ankle.
Physical Exam
  • Of primary importance is the determination of whether the condition is rigid or flexible.
    • Rigid flatfoot:
      • Loss of the normal longitudinal arch of the foot at all times
      • Restricted motion of the hindfoot
    • Flexible flatfoot:
      • Loss of arch only on standing on the
        affected foot, with reconstitution of the arch when the foot is
        dependent or when the patient toe-stands
      • Normal motion of the hindfoot
  • Increasing severity is associated with forefoot abduction and the “too many toes” sign when the patient is viewed from behind.
  • Inversion against resistance may be absent or diminished in patients with PTT dysfunction.
    • The patient may have pain or difficulty when attempting a single-limb heel rise on the affected side.
  • The foot should be inspected for deformity or swelling and then palpated for tenderness.
  • Gait pattern should be assessed.
    • An antalgic gait may indicate a painful condition such as arthritis or tendinitis.
    • The patient may have impaired propulsion with PTT abnormality.
    • An awkward, foot-slapping gait may suggest a neurologic or neuromuscular disease (e.g., spina bifida or poliomyelitis).
  • The Achilles tendon should be examined to test whether the heel cord is tight.
  • Radiography:
    • 3 standing radiographic views of the
      patient’s ankle (AP, lateral, and mortise) and 3 views of the patient’s
      foot (AP, lateral, and oblique) should be obtained.
    • The calcaneal pitch is diminished and may approach 0° with more severe flatfoot deformity.
    • The talus-1st metatarsal angle increases with loss of arch.
      • This angle should normally be 0° with the talus and metatarsal collinear.
      • Angle measurements: ≤15°, minor pes planus deformity; 15–30°, moderate deformity; >30°, severe deformity
    • When tarsal coalition is suspected:
      • Assess oblique radiograph for a calcaneonavicular coalition.
      • Obtain a CT scan to rule out a talocalcaneal coalition.
    • Assess the degree of hindfoot or midfoot arthritis.
    • Rule out bony fragmentation indicative of Charcot arthropathy.
  • An MRI scan may be useful for visualizing PTT abnormality.
Pathological Findings
  • Secondary to underlying cause:
    • Charcot arthropathy: Fragmentation, resorption of bone
    • PTT dysfunction: Degeneration, tearing, hypertrophy
    • Tarsal coalition: Fibrous, fibrocartilaginous, or osseous coalition
Differential Diagnosis
  • Pediatric flatfoot:
    • Benign flexible flatfoot
    • Tarsal coalition
    • Congenital vertical/oblique talus
    • Accessory navicular
  • Adult acquired flatfoot:
    • PTT dysfunction or tear
    • Midfoot arthritis
    • Charcot arthropathy
    • Neuromuscular disorders


General Measures
  • No treatment needed if asymptomatic
  • Pediatric:
    • Benign flexible flatfoot:
      • Shoes with good arch support
      • Consider orthotic device (e.g., prefabricated or custom-made medial arch support).
    • Tarsal coalition:
      • Initially, immobilization with a below-the-knee cast or boot brace
      • Rest and temporary activity restriction
    • Flatfoot secondary to a tight Achilles tendon may be relieved by physical therapy and heel-cord stretching.
  • Adult:
    • PTT dysfunction or tear:
      • NSAIDs and rest
      • Short-term immobilization with a below-the-knee cast or boot brace
      • Long-term maintenance with custom orthotic arch support or ankle-foot orthosis (brace)
      • Injection of corticosteroids is not recommended because it may weaken or rupture the tendon.
      • Weight loss
    • Midfoot arthritis:
      • Orthotic arch support
      • NSAIDs
      • Foot wear modifications (e.g., rocker-bottom and steel shank)
      • Intra-articular corticosteroid injections
    • Charcot arthropathy:
      • Acutely: Total contact cast and restricted weightbearing
      • Long-term: Orthotics and/or bracing
    • Surgical treatment is indicated for failure of nonoperative treatment.
Special Therapy
Physical Therapy
  • Physical therapy can be used to increase ankle and foot ROM and to stretch a tight Achilles tendon.
  • Orthotists can fabricate appropriate orthotic devices.
  • NSAIDs:
    • Can be used if swelling and pain are substantial
    • Are most useful for acute injuries or for patients with posterior tibial tendinitis.
  • Indicated for failure of nonoperative treatment, progression of deformity, or instability (13)
    • Surgical treatment may entail fusion, osteotomies, and possible soft-tissue procedures.
    • Age, activity level, degree of deformity, and comorbid conditions play a role in determining the extent of surgical treatment.
  • Pediatric flexible flatfoot:
    • Surgical treatments usually consist of
      osteotomies that realign the foot to correct valgus and improve
      mechanical alignment of the foot and ankle.
  • Rigid flatfoot from tarsal coalition:
    • Resection of tarsal coalition with interposition of fat or muscle
    • For patients with talocalcaneal coalition
      involving >50% of the joint surface or those with degenerative joint
      arthritis, subtalar arthrodesis is indicated.
  • Flatfoot secondary to a tight Achilles tendon:
    • Tendon lengthening involves a Z-lengthening procedure or partial sectioning of the tendon.
  • Acquired flatfoot secondary to PTT synovitis:
    • In early stages of the disease, synovectomy may be sufficient.
    • Flexible deformities are corrected with
      tendon transfers, calcaneal and midfoot osteotomies, and/or limited
      hindfoot arthrodesis.
  • Fusion is necessary for arthritis or rigid flatfoot deformity.
Most patients do not develop progressive deformities and do not need corrective surgery.
  • Most patients have little risk of complications with nonoperative treatment.
  • 1 major exception is patients with PTT dysfunction (acquired flatfoot) because they may develop a rigid flatfoot.
Patient Monitoring
Patients should be followed at 3-month intervals to
monitor their discomfort and function and to check whether their
deformity is stable or progressive.
1. Chang FM. The flexible flatfoot. Instr Course Lect 1988;37:109–110.
2. Chu IT, Myerson MS, Nyska M, et al. Experimental flatfoot model: the contribution of dynamic loading. Foot Ankle Int 2001;22: 220–225.
3. Jones LJ, Todd WF. Abnormal biomechanics of flatfoot deformities and related theories of biomechanical development. Clin Podiatr Med Surg 1989;6:511–520.
4. Kitaoka HB, Ahn TK, Luo ZP, et al. Stability of the arch of the foot. Foot Ankle Int 1997;18: 644–648.
5. Gould N, Schneider W, Ashikaga T. Epidemiological survey of foot problems in the continental United States: 1978–1979. Foot Ankle 1980;1:8–10.
6. Leonard MA. The inheritance of tarsal coalition and its relationship to spastic flat foot. J Bone Joint Surg 1974;56B:520–526.
7. Palladino SJ, Schiller L, Johnson JD. Cubonavicular coalition. J Am Podiatr Med Assoc 1991;81:262–266.
8. Harris
EJ. The oblique talus deformity. What is it, and what is its clinical
significance in the scheme of pronatory deformities? Clin Podiatr Med Surg 2000;17:419–442.
9. Hefti F. [Foot pain]. Orthopade 1999;28: 173–179.
10. Kumar SJ, Cowell HR, Ramsey PL. Vertical and oblique talus. Instr Course Lect 1982;31: 235–251.
11. Sullivan JA. Pediatric flatfoot: evaluation and management. J Am Acad Orthop Surg 1999;7: 44–53.
12. Tonnis D. [Skewfoot]. Orthopade 1986;15: 174–183.
13. Henceroth WD, II, Deyerle WM. The acquired unilateral flatfoot in the adult: some causative factors. Foot Ankle 1982;2:304–308.
  • 734.0 Acquired flat foot
  • 754.61 Congenital flat foot
Patient Teaching
  • Patient education is crucial because cosmesis in the absence of symptoms is not an appropriate indication for surgery.
  • Stretching exercises can help patients
    with tight Achilles tendons, and foot orthoses may be useful for
    patients who want to be active.
Q: What are 3 causes of flatfoot deformity in pediatric patients?
A: Benign flexible flatfoot, tarsal coalition, and congenital vertical talus.

Q: What are 3 causes of flatfoot deformity in adults?
A: PTT dysfunction (most common cause of adult acquired flatfoot), neuroarthropathy, and degenerative or inflammatory arthritis.

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