Tarsal coalition

Tarsal coalition describes complete or partial union between two or more bones in the midfoot and hindfoot. Tarsal coalition refers to developmental fusion rather than fusion that is acquired secondary to conditions such as rheumatoid arthritis, trauma or post-surgical.

It occurs in ~5% of the population and although congenital, patients typically present in adolescence. There is a significant male predilection (M:F 4:1) 5. 50% are bilateral (even if symptomatic only on one side). Pes planus (flat foot) is usually a feature. 

Clinical presentation is usually delayed until adolescence and is due to either increased mechanical strain on the joints/structures on either side of the coalition or in some instances due to direct impingement due to the hypertrophic coalition 5. The condition is bilateral in up to 50% of cases, and clinical presentation includes:

Tarsal coalition is believed to be the result of incomplete or faulty segmentation during development. They may be of three types, depending on the tissue which bridges between the two bones. The three types are 1:

Associations

The vast majority (90%) of tarsal coalitions are either:

The remainder of the coalitions (calcaneocuboid, talonavicular, cubonavicular) are much less common 3

Plain radiograph

Plain films are usually the first investigation of choice, and in many instances yield that diagnosis. Plain film findings are most apparent when there is bony coalition, especially where the bony bar is large enough and the medullary cavity is seen in continuity between the two bones. In fibrous coalitions, there is irregularity and narrowing of the bony interfaces, and there is usually associated sclerosis.

General features of non-osseous coalition include:

  • subchondral reactive bony changes
  • adjacent marrow oedema (MR)
  • unusual articular orientation
  • joint space loss
MRI

May help distinguish between:

  • osseous coalition
    • continuity of marrow signal
  • fibrous coalition
    • proximity of surfaces with loss of fat plane
    • low signal on T1/T2 weighted sequences
  • cartilaginous coalition
    • proximity of surfaces with loss of fat plane
    • intermediate T2/STIR +/- fluid signal

Possible associated findings include marrow or soft tissue oedema

Although conservative (non-surgical) therapy may be useful in alleviating pain, symptomatic improvement is usually short lived since it does not address the underlying anatomic abnormality 6

Surgical management usually involves an osteotomy and removal of the whole coalition. The space is then filled with soft tissues (e.g. muscle). 


Lower limb anatomy
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Article Information

rID: 2148
Sections: Anatomy, Pathology
Synonyms or Alternate Spellings:
  • Tarsal coalitions

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Cases and Figures

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    Case 1: calcaneonavicular
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    Case 2: calcaneonavicular
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    Case 3: calcaneonavicular
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    Calcaneonavicular...
    Case 4: calcaneonavicular
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    Calcaneonavicular...
    Case 5: calcaneonavicular
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    Case 6: talocalcaneal
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    Talocalcaneal coa...
    Case 7: talocalcaneal
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    Case 8: talocalcaneal
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    Calcaneonavicular...
    Case 9: calcaneonavicular (bilateral)
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    Case 10: both types
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    Case 11: calcaneonavicular
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    Anteater sign
    Case 12: calcaneonavicular
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    Case 13: talocalcaneal
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    Case 14: talocalcaneal
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    Case 15: cubonavicular
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    Case 16: calcaneo-navicular
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    Case 17: calcaneonavicular coalition
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