skeletal system disorder flatfoot MESH:D005413 ICD9:734 NCIT:C34616 An anatomic deformity in which the arch of the foot collapses, resulting in the entire sole of the foot coming into complete or near-complete contact with the ground. fallen Arch EFO:0003874 SCTID:53226007 MONDO:0005293 UMLS:C0016202 flat Foot MEDGEN:42034