Pes Planus

Radiographic findings typically include:

  • DP View
    • increased talocalcaneal angle
    • increased cuboid abduction angle
    • decreased forefoot adductus angle
    • decreased talonavicular joint "congruency"
  • Lateral View
    • increased talar declination angle
    • decreased calcaneal inclination angle
    • decreased 1st metatarsal declination angle
    • anterior break in the cyma line
    • naviculocuneiform "fault"

Contributing Factors

  • leg length difference
  • equinus
  • posterior tibial tendon dysfunction
  • Kidner foot
  • tarsal coalition
  • skewfoot
  • rheumatoid arthritis

Here are some examples of pes planus followed by interpretations (*):

  • Case 1a
  • Case 1b
  • *Case 1a
  • *Case 1b
  • Case 2a
  • Case 2b
  • *Case 2a
  • *Case 2b
  • Case 3a
  • Case 3b
  • *Case 3a
  • *Case 3b
  • *Case 3c
  • Case 4a
  • Case 4b
  • *Case 4a
  • *Case 4b
  • Case 5
  • *Case 5
  • Case 6a
  • Case 6b
  • *Case 6a
  • *Case 6b
  • Case 7a
  • Case 7b
  • *Case 7a
  • *Case 7b
pes planus dp
pes planus lateral
pes planus dp

DP view. Findings include increased talocalcaneal and cuboid abduction angles; the forefoot adduction angle is decreased. Talonavicular joint "congruency" is approximately 50%. Diagnosis: pes planus.

pes planus lateral

Lateral view. Findings include decreased calcaneal inclination and 1st metatarsal declination angles; the talar declination angle is increased. The cyma line is "broken" anteriorly. Diagnosis: pes planus.

CN bar Lateral oblique
CN bar Lateral
CN bar Lateral oblique

Medial oblique view. Findings include union between the anterior calcaneal process and the navicular bone (arrows). (C = calcaneus; N = navicular) Diagnosis: calcaneonavicular bar.

CN bar lateral

Lateral view. Findings include an extension of the calcaneal anterior process (arrow) commonly referred to as the "anteater calcaneus". (C = calcaneus; N = navicular) Diagnosis: Calcaneonavicular bar.

MTCJ Coalition Lateral
MTCJ Coalition Axial
MTCJ Coalition Lateral

Lateral view. Findings include union between the talar posterior-medial process (PM) and the sustentaculum tali (ST); the continuity of the inferior margins of these landmarks with the ankle joint form what has been coined the "C sign". (See *Case 3c for a normal comparison view.) The talar lateral process (LP) is rounded/flattened inferiorly (it normally is more pointed). Diagnosis: middle talocalcaneal joint coalition.

MTCJ Coalition Harris-Beath view normal harris-beath view

Harris-Beath views (right image is a normal for comparison). Findings include union (arrows) between the elongated talar posterior-medial process (PMP) and the sustentaculum tali (ST). (PTCJ = posterior talocalcaneal joint; MTCJ = middle talocalcaneal joint.) Diagnosis: middle talocalcaneal joint coalition.

Normal Lateral view CT  MTCJ coalition

Lateral view (a normal for comparison to case 3a). The arrow identifies the normal separation between the talar posterior-medial process (PMP) and the sustentaculum tali (ST).

CT coronal plane image. Findings include union (arrow) between the elongated talar posterior-medial process and the sustentaculum tali. (T = talus; C = calcaneus.) Diagnosis: middle talocalcaneal joint coalition.

pes planus KIDNER
Pes planus Kidner lateral view
Pes planus Kidner DP

DP view. Findings include an accessory navicular type 3 (AN3); increased talocalcaneal and cuboid abduction angles; and the forefoot adduction angle is decreased. Talonavicular joint "congruency" is less than 75%. Diagnosis: pes planus/Kidner foot.

Pes planus Kidner lateral

Lateral view. Findings include decreased calcaneal inclination and 1st metatarsal declination angles; the talar declination angle is increased. The cyma line is "broken" anteriorly. Diagnosis: pes planus/Kidner foot (based upon DP view findings).

Ankle equinus lateral
ankle equinus lateral marked

Lateral view. Findings include osteophytes (arrows) along the anterior aspect of the ankle joint. Diagnosis: osteoarthritis/bony equinus. Incidental findings include inferior and retrocalcaneal spurs (diagnosis: enthesopathy) and osteophytes posterior to the talocalcaneal joint (diagnosis: osteoarthritis).

rheumatoid DP
rheumatoid lateral
rheumatoid dp marked

DP view. Findings include increased talocalcaneal and cuboid abduction angles; the forefoot adductus angle is decreased. Talonavicular joint "congruency" is approximately 50%. Other findings include subtle erosion at the margins of multiple metatarsophalangeal joints; pseudocysts in the 2nd metatarsal head; less than 100% apposition at the 1st MPJ; increased soft tissue density medial to the 1st MPJ; increased intermetatarsal and hallux abductus angles. Diagnosis: pes planus/rheumatoid arthritis/HAV with bunion deformity and subluxation of the 1st MPJ/rheumatoid nodule versus inflammation 1st MPJ.

rheumatoid lateral marked

Lateral view. Findings include decreased calcaneal inclination and 1st metatarsal declination angles; the talar declination angle is increased. The cyma line is "broken" anteriorly. Other findings include inferior calcaneal spur and erosion of calcaneal bursal projection. Diagnosis: pes planus/rheumatoid arthritis/enthesopathy.

skewfoot dp
skewfoot lateral
skewfoot dp marked

DP view. Findings include increased talocalcaneal, cuboid abduction, and metatarsus adductus (Engle's) angles; the forefoot adduction angle is decreased. Talonavicular joint "congruency" is less then 75%. Diagnosis: pes planus/skewfoot.

skewfoot lateral marked

Lateral view. Findings include decreased calcaneal inclination and 1st metatarsal declination angles; the talar declination angle is increased. The cyma line is "broken" anteriorly. Other findings include a retrocalcaneal spur. Diagnosis: pes planus/skewfoot (in light of DP view findings)/enthesopathy.

Should a radiographic study be ordered for evaluation of pes planus?

Yes, if symptomatic.

What are the best views to order?

At a minimum, order dorsoplantar and lateral views.

  • Lateral oblique view should be added when considering accessory navicular;
  • Include the Harris-Beath view for suspected middle talocalcaneal coalition;
  • Add the medial oblique view when calcaneonavicular bar is suspected.
When should additional imaging studies be ordered?

CT can be valuable when fibrocartilaginous middle talocalcaneal coalition is suspected and plain films are questionable.

MRI is useful for assessment of posterior tibial tendon dysfunction.

Related Reference

Kidner FC. The pre-hallux (accessory scaphoid) in its relation to flatfoot. J Bone Joint Surg. 1929;11:831-837.

References:

  1. Christman, RA: Foot and Ankle Radiology, Churchill Livingstone, 2003.
  2. Nalaboff KM, Schweitzer ME: MRI of tarsal coalition: frequency, distribution, and innovative signs. Bull NYU Hosp Jt Dis 66(1):14-21, 2008.
  3. Lateur, LM et al: Subtalar coalition: diagnosis with the C sign on lateral radiographs of the ankle. Radiology 193:847, 1994
  4. Crim JR, Kjeldsberg KM: Radiographic Diagnosis of Tarsal Coalition. AJR 182(2):323-328, 2004(Feb)