Items tagged “bone”

24 results found
Article

Os acromiale

Os acromiale is an anatomical variant and represents an unfused accessory center of ossification of the acromion of the scapula. Epidemiology Os acromiale are relatively common, seen in ~8% (range 1-15%) of the population 1,2 and may be bilateral in 60% of individuals 5. Clinical presentation...
Article

Os odontoideum

Os odontoideum is an anatomic variant of the odontoid process of C2 and needs to be differentiated from persistent ossiculum terminale and from a type 2 odontoid fracture. It can be associated with atlantoaxial instability.  Although it was originally thought to be a congenital lesion due to a ...
Article

Os tibiale externum

An os tibiale externum, also known as an accessory navicular or os naviculare accessorium, is a large accessory ossicle that can be present adjacent to the medial side of the navicular bone. The tibialis posterior tendon often inserts with a broad attachment into the ossicle. Most cases are asym...
Article

Acetabular foramen

The acetabular foramen is formed by the bony margins of the acetabular notch and completed by the transverse ligament of the hip. From its margins (both transverse ligament and acetabular notch) arises the ligamentum teres. Through it pass nutrient vessels to the femoral head epiphysis.
Article

Fluid-fluid level containing bone lesions

Fluid-fluid level containing bone lesions are best seen on MRI, although with narrow window width they can also be appreciated on CT. Epidemiology Their prevalence is estimated at ~3% of bone and soft tissue tumors 1. Differential diagnosis Their presence is non-specific, as they are seen in...
Article

Os peroneum

An os peroneum is a small accessory bone located at the lateral plantar aspect of the cuboid within the substance of the peroneus longus tendon as it arches around the cuboid. It is a very common anatomical variant, seen in up to 26% of feet 1. Differential diagnosis It should not be mistaken ...
Article

Os trigonum

The os trigonum (plural: os trigona) is one of the ossicles of the foot and can be mistaken for a fracture.  It sits posterior to the talus on the lateral foot radiograph and represents a failure of fusion of the lateral tubercle of the posterior process. It is estimated to be present in ~7% of...
Article

Os calcaneus secundarius

An os calcaneus secundarius is an accessory ossicle of the anterior calcaneal process present in up to 5% of the population at cadaveric examination. The ossicle can be a cause of ankle pain and may mimic bifurcated ligament avulsion fracture of the anterior calcaneal process. Differential diag...
Article

Bipartite patella

A bipartite patella (two-part patella) is a patella with an unfused accessory ossification center at the superolateral aspect. Epidemiology The superolateral accessory ossification center of the patella is usually present by 12 years of age and may persist into adult life. Prevalence of a bipa...
Article

Enostosis

Enostoses, also known as bone islands, are common benign sclerotic bone lesion which usually represent incidental findings. They constitute a small focus of compact bone within cancellous bone. Enostoses can be seen on radiographs, CT, and MRI, and are considered one of the skeletal “don’t touch...
Article

Accessory sutures

The parietal and occipital bones in particular are common regions for accessory sutures because of their multiple ossification centers. It is important to know these anatomic variations, mainly on the head trauma image studies in children, where it could be difficult to differentiate non-depres...
Article

Os subfibulare

Os subfibulare is an accessory ossicle that lies at the tip of the lateral malleolus of the ankle and is rarely reported 1. Clinical presentation Os subfibulare are usually asymptomatic although they may eventually cause painful syndromes or degenerative change in response to overuse and traum...
Article

Os subtibiale

An os subtibiale is a rare, genuine accessory ossicle and normal variant related to the posterior colliculus of the medial malleolus 1. It is present in ~1% of the population 5.  Clinical presentation They usually are asymptomatic although they may eventually cause painful syndromes or degener...
Article

Accessory superior acetabular notch

An accessory superior acetabular notch is a normal variant of the acetabulum, which can be seen on radiographs. It may lead to diagnostic confusion, especially in younger patients.  Radiographic features MRI appear as bilateral symmetric fluid-filled pits in the roof of the acetabulum with sh...
Article

Os hamuli proprium

The hook of the hamate has its own ossification center, which may fail to fuse with body of the hamate, creating an ossicle. This ossicle is reffered to as an os hamuli proprium or unfused hamulus  In some instances, this can be difficult to distinguish from a fracture of the hook, but is sugge...
Article

Accessory ossicles of the wrist (mnemonic)

Accessory ossicles of the wrist can be easily recalled with the mnemonic: LOTTEO 1 HOTELS Mnemonic LOTTEO L: lunula O: os styloideum (carpal boss) T: (os) triangulare T: (os) trapezium secondarium E: (os) epilunate O: os hamuli proprium HOTELS H: (os) hamuli proprium O: os triangula...
Article

Accessory ossicles of the wrist

Accessory ossicles of the wrist are commonly seen on plain radiographs of the wrist and associated cross-sectional imaging. Over 20 were originally described 2, although the more common include 1: lunula: between TFCC and triquetrum os styloideum (carpal boss): on dorsal surface of 2nd or 3rd ...
Article

Multipartite hallux sesamoid

Multipartite hallux sesamoids are a commonly seen normal variant, present in up to 33% of hallux sesamoids. They are more commonly bipartite than tripartite.  The medial (tibial) sesamoid is more likely to be multipartite than the lateral (fibular) sesamoid because it more commonly has more tha...
Article

Angiosarcoma (bone)

Angiosarcoma of bone is a malignant vascular tumor of bone. These are rare and account for less than 1% of malignant bone tumors. The majority of these tumors arising in bone are primary; however, a tiny percentage is either radiation-induced or associated with bone infarction Epidemiology Mos...
Article

Tumors that metastasize to bone (mnemonic)

Tumors that metastasize to bone may be remembered using the mnemonic "lead kettle" spelled PBKTL (lead is Pb on the Periodic Table). PB-KTL Mnemonic P: prostate B: breast K: kidney T: thyroid L: lung For females, breast and lung are the most common primary sites; nearly 80% of cancers th...

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