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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/09/15 06:32:41」(JST)

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X-ray showing synostosis in the cervical spine

Synostosis (plural: synostoses) is fusion of two bones. It can be normal in puberty, fusion of the epiphysis, or abnormal. When synostosis is abnormal it is a type of dysostosis.

Examples of synostoses include:

craniosynostosis – an abnormal fusion of two or more cranial bones;
radioulnar synostosis – the abnormal fusion of the radius and ulna bones of the forearm;
tarsal coalition – a failure to separately form all seven bones of the tarsus (the hind part of the foot) resulting in an amalgamation of two bones; and
syndactyly – the abnormal fusion of neighboring digits.

Synostosis within joints can cause ankylosis.

Clinical significance

Radioulnar synostosis is one of the more common failures of separation of parts of the upper limb. There are two general types: one is characterized by fusion of the radius and ulna at their proximal borders and the other is fused distal to the proximal radial epiphysis. Most cases are sporadic, congenital (due to a defect in longitudinal segmentation at the 7th week of development) and less often post-traumatic, bilateral in 60%, and more common in males. Familial cases in association with autosomal dominant transmission appear to be concentrated in certain geographic regions, such as Sicily.

The condition frequently is not noted until late childhood, as function may be normal, especially in unilateral cases. Increased wrist motion may compensate for the absent forearm motion. It has been suggested that individuals whose forearms are fixed in greater amounts of pronation (over 60 degrees) face more problems with function than those with around 20 degrees of fixation. Pain is generally not a problem, unless radial head dislocation should occur.^[1]^[2]

Most examples of radioulnar synostosis are isolated (non-syndromic). Syndromes that may be accompanied by radioulnar synostosis include X chromosome polyploidy (e.g., XXXY) and other chromosome disorders (e.g., 4p- syndrome, Williams syndrome), acrofacial dysostosis, Antley–Bixler syndrome, genitopatellar syndrome, Greig cephalopolysyndactyly syndrome, hereditary multiple osteochondromas (hereditary multiple exostoses), limb-body wall complex, and Nievergelt syndrome. craniosynostosis (from cranio, cranium; + syn, together; + ostosis relating to bone) is a condition in which one or more of the fibrous sutures in an infant skull prematurely fuses by turning into bone (ossification).^[3]^{[better source needed]} Craniosynostosis has following kinds: Scaphocephaly , Trigonocephaly Plagiocephaly Anterior Plagiocephaly Posterior Plagiocephaly Brachycephaly Oxycephaly Pansynostosis .

References

^ "Radioulnar Synostosis". wheelessonline.com. Retrieved 24 April 2015.
^ Boston Childrens Hospital 2013. "Conditions + Treatments". childrenshospital.org. Retrieved 24 April 2015.
^ Craniosynostosis

External links

Synostosis at the US National Library of Medicine Medical Subject Headings (MeSH)

UpToDate Contents

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English Journal

Mutations in the NOG gene are commonly found in congenital stapes ankylosis with symphalangism, but not in otosclerosis.

Usami S, Abe S, Nishio S, Sakurai Y, Kojima H, Tono T, Suzuki N.SourceDepartment of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Otorhinolaryngology, Abe ENT Clinic, Ota-ku, Japan Department of Otorhinolaryngology, Jikei University School of Medicine, Minato-ku, Tokyo, Japan Department of Otorhinolaryngology, University of Miyazaki Faculty of Medicine, Miyazaki, Japan.
Clinical genetics.Clin Genet.2012 Dec;82(6):514-20. doi: 10.1111/j.1399-0004.2011.01831.x. Epub 2012 Jan 30.
Usami S, Abe S, Nishio S, Sakurai Y, Kojima H, Tono T, Suzuki N. Mutations in the NOG gene are commonly found in congenital stapes ankylosis with symphalangism, but not in otosclerosis. Human noggin (NOG) is a responsible gene for multiple synostosis syndrome (SYNS1) and proximal symphalangism (SYM1
PMID 22288654

Surgical outcome after using a modified technique of the pi-procedure for posterior sagittal suture closure.

Engel M, Freudlsperger C, Hoffmann J, Mühling J, Castrillón-Oberndorfer G, Seeberger R.SourceDepartment of Oral and Maxillofacial Surgery, University Hospital Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany. Electronic address: Michael.engel@med.uni-heidelberg.de.
Journal of cranio-maxillo-facial surgery : official publication of the European Association for Cranio-Maxillo-Facial Surgery.J Craniomaxillofac Surg.2012 Dec;40(8):e363-8. doi: 10.1016/j.jcms.2012.01.024. Epub 2012 Mar 13.
Fusion of the sagittal suture is the most prevalent form of craniosynostosis. Due to the variety of deformities of scaphocephaly depending on the location of the fused sagittal suture, the surgical procedure has to be adjusted to the individual case. In this study, 38 patients with a predominantly p
PMID 22417770