Last revised by Tom Foster on 30 May 2020

A coalition is a joining of two bones that are normally discrete 1. It is usually a congenital abnormality. The bridge between the bones is initially fibrous, then gradually becomes cartilaginous, finally ossifying. Symptoms tend to arise as the coalition forms a synostosis, which is usually from 8 to 16 years of age 2,3


Many rarer coalitions have been reported in the literature.

History and etymology

Coalition is derived from the Latin word 'coalescere' which means to grow together 1.

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Cases and figures

  • Case 1: calcaneonavicular coalition
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  • Case 2: luno-triquetral coalition
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