Os tibiale externum
| Classification according to ICD-10 | |
|---|---|
| M92.6 | Juvenile osteochondrosis of the tarsus |
| ICD-10 online (WHO version 2019) | |
The Os tibiale externum (syn .: Os naviculare externum , Os naviculare secundarium , Os naviculare accessorium , Os naviculare bipartitum ; English : accessory tarsal navicular , accessory tarsal scaphoid ) is a frequent (10-16%) variation on the navicular bone of the foot ( navicular bone ). In over half of the cases it occurs on both sides.
clinic
There is a hard swelling in the sense of an overbone on the inner tarsus, about a finger's breadth below and in front of the tip of the inner ankle , i.e. on the navicular bone. Occasionally, pain and pressure pain occur, especially when this malformation occurs together with flat feet . The diagnosis is confirmed with an X-ray .
variants
There are three different forms of the Os tibiale externum :
- Type 1 : The Os tibiale externum in the narrower sense is a 2–3 mm large, roundish sesamoid bone in the attachment area of the tendon of the musculus tibialis posterior . It does not form any cartilage to the navicular bone.
- Type 2 : The Os tibiale externum is triangular and up to 9 mm in size. This has a cartilage connection to the navicular bone. This type is the most common with over 50%. It is a failure to fuse the bone nuclei from which the navicular bone is formed in early youth.
- Type 3 : Here the scaphoid bone is developed in a way that expands inwardly ( Os naviculare cornutum , English: cornuate navicular ). In contrast to the first two forms, no gap can be seen here.
therapy
The os tibiale externum is usually asymptomatic, so it does not cause any symptoms. Treatment is then not necessary. Otherwise, the swelling is treated with custom-made insoles with soft padding. An operation should only be considered in extreme exceptional cases, if conservative therapy has failed and there is severe suffering.
literature
- Carl Joachim Wirth: Orthopedic Practice , Georg Thieme Verlag, Stuttgart / New York, 2001, ISBN 3-13-125683-4
- Joachim Brossmann, Christian Czerny, Jürgen Freyschmidt: Limits of the normal and the beginnings of the pathological in the radiology of the child and adult skeleton , 13th edition. Georg Thieme Verlag, Stuttgart / New York, 2001, ISBN 3-13-362214-5
