Canadian C-spine rules are a set of guidelines that help a clinician decide if cervical spine imaging is not appropriate for a trauma patient in the emergency department. The patient must be alert and stable.
There are three rules:
is there any high-risk factor present that requires cervical s...
The capitate (or os magnum) is the largest of the carpal bones and sits at the centre of the distal carpal row. A distinctive head shaped bone, it has a protected position in the carpus.
The capitate sits in a proximo-distal direction with a waist that is proximal to...
Capito-hamate coalition is the second most common type of carpal coalition and represents congenital fusion of the capitate and the hamate. It represents ~5% of all carpal fusions 1 and is associated with Apert syndrome 2.
The capitolunate angle is the angle between the long axis of the capitate and the mid axis of the lunate on the sagittal imaging of the wrist. In a normal situation it should be less than 30o in the resting (neutral) position.
The angle is increased in carpal instability such as with a dorsal i...
There is variation in the relationship between the glenoid labrum and the anterior shoulder joint capsule. This has been divided into three types:
Type 1: capsule inserts into the labrum proper
Type 2: capsule inserts into the base of the labrum, or within 1cm of the base
Type 3: capsule inse...
Carcinogens are substances known to cause cancer. They include:
Nasopharynx / nasal passage
ionising radiation (not technically a substance)
polyaromatic hydrocarbons (PAH)
Carpal angle is defined by two intersecting lines, one in contact with the proximal surface of the scaphoid and the lunate and the other line through proximal margins of the the triquetrum and the lunate. Its normal value is between 130° and 137°.
It is increased in (> 139°)
Carpal bone fractures comprise a range of different fractures which carry varying outcomes. They can involve one or a combination of carpal bones and also be part of fracture-dislocations.
Individual fractures include
scaphoid fracture: 50-80%
lunate fracture: 3.9%
triquetral fracture: ~18%
The carpal bones are the eight bones of the wrist that form the articulation of the forearm with the hand. They can be divided in two rows:
The names and order of these bones can be rememb...
Mnemonics of the carpal bone are numerous and useful for memorising the order and location of the bones. They usually describe the position of the carpal bones from lateral to medial in the proximal row and then the distal row:
Sam Likes To Push The Toy Car Hard
She Looks Too Pretty Try To Cat...
The carpal boss is an unmovable hypertrophied bony protuberance at the base of the second or third metacarpals on the dorsal surface, near the capitate and trapezium.
The condition may represent either or a combination of:
degenerative osteophyte formation
os styloideum (an access...
Carpal coalition refers to fusion of two or more carpal bones, and although the most commonly involved bones are the lunate and triquetrum, most combinations of adjacent bones can be found to be coalesced.
The estimated prevalence is ~0.1% in Caucasian Americans and ~1.5% in Afri...
Carpal height is used to diagnose and assess the severity of carpal collapse. It is defined as the distance between the base of third metacarpal and the subchondral bony cortex of the distal radius. But due to variations between individuals, it is more appropriate to calculate the carpal height ...
The carpal tunnel is a fibro-osseous canal that acts as a passageway from the forearm to the anterior hand. It is found in the anterior wrist.
superficial border (roof): flexor retinaculum
deep border (floor): carpal bones
The carpal tunnel contains the fo...
Carpal tunnel syndrome (CTS) results from compression of the median nerve within the carpal tunnel. It is a cause of significant disability and is one of three common median nerve entrapment syndromes, the other two being anterior interosseous nerve syndrome and pronator teres syndrome.
Carpal tunnel syndrome results from compression of the median nerve within the carpal tunnel. Its causes are numerous and varied.
A useful mnemonic to remember the various pathologies is MEDIAN TRAP:
D: diabetes mellitus
Carpenter syndrome, also called acrocephalopolysyndactyly type II (ACPS type II) is an extremely rare autosomal recessive congenital disorder
It is characterized by number of features which include:
kleeblattschädel (cloverleaf ...
Carpometacarpal (CMC) joint dislocations are an uncommon dislocation of the hand.
There is a strong younger male predominance in the dominant hand.
The most common mechanisms of injury are punching followed by a fall.
The patient may present with ulnar dev...
Carrying angle is a small degree of cubitus valgus, formed between the axis of a radially deviated forearm and the axis of the humerus. It helps the arms to swing without hitting the hips while walking.
Normally it is 5-15o away from the body or 165-175o towards the body.
A decreased carrying ...
Cartilage interface sign, also referred to as double cortex sign, refers to the sonographic presence of a thin markedly hyperechoic line at the interface between the normally hypoechoic hyaline articular cartilage of the humeral head and an abnormally hypoechoic supraspinatus tendon. This arises...
Cartilaginous joints are a type of joint where the bones are entirely joined by cartilage, either hyaline cartilage or fibrocartilage. These joints generally allow more movement than fibrous joints but less movement than synovial joints.
Primary cartilaginous joint
These cartilaginous joints...
The differential for cartilagenous lesions includes:
The cases featured in these video lectures are specifically selected to teach important concepts in radiology over a broad range of topics. The tutorials vary in difficulty from basic to advanced. For maximum learning, try the cases for yourself in Radiopaedia quiz mode first.
We love this ser...
The Castellvi classification is used for lumbosacral transitional vertebra (LSTV):
type I: enlarged and dysplastic transverse (at least 19 mm)
type II: pseudoarticulation of the transverse process and sacrum with incomplete lumbarisation/sacralisation; enlargemen...
The Caton-Deschamps index is a ratio that is used in everyday practice as well as in research to measure patellar height and allows the diagnosis of patella alta and patella baja.
The Caton-Deschamps index is the ratio between the distance between the lower pole of the pa...
The Catterall classification is based on radiographic appearances of the epiphysis and metaphysis visible in osteonecrosis of the femoral head:
bone absorption changes visible in the anterior aspect of the epiphysis of femoral head
changes are visible best in frog leg lateral view
There are several important causes of an abnormal lunate signal on MRI, the most frequent causes being Kienbock disease (25%), ulnar impaction syndrome (25%) and intraosseous ganglia (20%).1 Appreciation of the pattern of bone signal change can often allow the correct diagnosis to be made.
A mnemonic for remembering the symmetric vs. asymmetric causes of sacroiliitis is:
P: psoriatic arthritis
A: ankylosing spondylitis
I: inflammatory bowel related
R: reactive (e.g. Reiter syndrome)
The outside letters P & R (letters are far apart) are the asymmetric causes an...
Cavernous venous malformation, also traditionally referred to as a cavernous haemangioma (despite it not being a tumour) or cavernomas, are non-neoplastic slow flow venous malformations found in many parts of the body.
Despite the ubiquity of use of the traditional terms cavernoma...
Celery stalk metaphysis refers to a plain film appearance of the metaphyses in a number of conditions characterised by longitudinally aligned linear bands of sclerosis. They are seen in:
congenital cytomegalovirus (CMV)
The celery stalk sign is a term given to the appearance of the anterior cruciate ligament which has undergone mucoid degeneration and has been likened to that of a celery stalk. Its low signal longitudinal fibres are separated from each other by higher signal mucinous material, best appreciated ...
Cellulitis (more specifically referred to as superficial cellulitis) is an acute infection of the dermis and subcutaneous tissues. It results in pain, erythema, oedema, and warmth. Since the epidermis is not involved, cellulitis is not transmitted by person-to-person contact.
Cenani-Lenz syndactyly (CLS) is a very syndrome primarily characterised by:
syndactyly/oligodactly: syndactyly is often complete and gives a spoon hand type appearance
It carries an autosomal recessive inheritance.
It was first described...
The central sacral vertical line (CSVL) is used in the assessment of spinal scoliosis.
It is a line constructed on frontal films of the spine and pelvis to measure coronal balance, drawn as follows:
a line connecting the top of the iliac crests is drawn
a second line is drawn perpendicular t...
Cerebrotendinous xanthomatosis is an autosomal recessive lipid storage disorder caused by defects in sterol-27-hydroxylase enzyme in bile acid synthesis. This leads to early cataract formation, atherosclerosis, hypercholesterolemia, and tendinous xanthomas.
Cervical canal stenosis can be acquired (e.g. trauma, discs, and ossification of the posterior longitudinal ligament) or congenital. It refers to narrowing of the spinal canal, nerve root canals, or intervertebral foramina of the cervical spine.
normal AP diameter is ~17 ...
Cervical degenerative changes can be graded using a very old but reliable classification given by Kellgren et al. It is based on findings on a lateral cervical spine radiograph although it can also be applied to MRI evaluation of spine.
The key parameters are osteophyte formation, intervertebra...
The cervical ligament attaches to the calcaneus and talus. It is lateral to the tarsal sinus and medial to the attachment of extensor digitorum brevis. It is taut in inversion.
Cervical ribs are supernumerary or accessory ribs arising from the seventh cervical vertebra. They occur in ~0.5% of the population, are usually bilateral, but often asymmetric 2, and are more common in females.
Although cervical ribs are usually asymptomatic, they are the most important anato...
The cervical spine is the upper part of the spine extending from the skull base to the thorax at the level of the first vertebra with a rib attached to it. It normally consists of seven vertebrae. Its main function is to support the skull and maintain the relative positions of the brain and spin...
Cervical spine flexion-extension lateral views are specialised projections of the cervical spine often requested to assess for spinal stability.
Cervical spine flexion-extension lateral views should not be performed on trauma patients without strict instructions of a qualified clinician.
A floating pillar, also referred as pedicolaminar fracture-separation injury, is characterised by fractures through the pedicle and lamina of a cervical spine vertebrae creating a free-floating articular pillar fragment. It is an unstable cervical spine fracture that results from hyperflexion–la...
There are several cervical spine fracture classification systems:
Anderson and D'Alonzo classification (odontoid fracture)
Roy-Camille classification (odontoid fracture)
Levine and Edwards classification (for traumatic injuries to axis)
Allen and Ferguson classification (subaxial spine injur...
Cervical spine fractures can occur secondary to exaggerated flexion or extension, or because of direct trauma or axial loading.
The cervical spine is susceptible to injury because it is highly mobile with relatively small vertebral bodies and supports the head which is both heavy and...
The closed mouth odontoid AP view (Fuchs view) is a nonangled AP radiograph of C1 and C2. This view focuses primarily on the odontoid process. The standard Fuchs view should not be used in a trauma setting and the modified Fuchs view may be used instead.
supine or erect
Cervical spine injuries can involve the cervical vertebral column, intervertebral discs and cervical spine ligaments, and/or cervical spinal cord. The cervical spine accounts for ~50% of all spinal injuries.
5-10% of patients with blunt trauma have a cervical spine injury 1.
Cervical spine lateral view is a lateral projection of the cervical spine. It is often performed in the setting of trauma.
As technology advances, computed tomography (CT) has replaced this projection, yet there remain many institutions (especially in rural areas) where CT is not readily availa...
Cervical spine ligaments ordered from anterior to posterior include:
anterior longitudinal ligament (ALL)
anterior atlanto-occipital membrane
alar ligaments (paired)
cruciate ligament of the atlas
longitudinal band: joins the body of the axis to the foramen magnum
The odontoid or 'peg' projection is an AP projection of C1 (atlas) and C2 (axis).
patient positioned erect in AP position unless trauma the patient will be supine
patient’s shoulders should be at equal distances from the image receptor to avoid rotation, the head facing strai...
The term cervical stenosis can refer to:
stenosis of the uterine cervix
bony cervical canal stenosis (cervical spinal stenosis)
Chalk stick or carrot stick fractures are fractures of the fused spine, classically seen in ankylosing spondylitis.
Some authors define the chalk stick fracture as a fracture through a Pagetoid long bone (see Paget disease).
They usually occur through the disco-vertebra...
Chamberlain line is a line joining the back of hard palate with the opisthion on a lateral view of the craniocervical junction.
It helps to recognise basilar invagination which is said to be present if the tip of the dens is >3 mm above this line.
McGregor developed a modificatio...
The champagne glass pelvis is a helpful sign in achondroplasia in which the iliac blades are flattened, giving rise to a pelvic inlet that resembles a champagne glass. The acetabular angles are flattened (horizontal) and the sacrosciatic notch is small.
Chance fractures, also referred to as seatbelt fractures, are flexion-distraction type injuries of the spine that extend to involve all three spinal columns. These are unstable injuries and have a high association with intra-abdominal injuries.
They tend to occur from a fl...
Charcot joint, also known as a neuropathic or neurotrophic joint, refers to a progressive degenerative/destructive joint disorder in patients with abnormal pain sensation and proprioception.
In modern Western societies by far the most common cause of Charcot joints is diabetes, an...
The causes of a Charcot joint can be remembered, with a little poetic license, as they (all) start with the letter S.
spinal cord injury
The features of Charcot arthropathy can be remembered...
Chauffeur fractures (also known as Hutchinson fractures or backfire fractures) are intra-articular fractures of the radial styloid process. The radial styloid is within the fracture fragment, although the fragment can vary markedly in size.
These injuries are sustained eit...
The Chauveaux–Liet angle (CL angle) is represented by the difference between the angle of verticalization (α) and morphologic angle (β) of the calcaneus (CL angle = α − β).
Angle α is the calcaneal pitch angle or angle of verticalization of calcaneus described as the intersection of the baselin...
The Cheerio sign has been described as a sign seen in a type III superior labral anterior posterior tear (SLAP lesion) of the glenoid labrum. In the cheerio sign, a rounded core of soft tissue is surrounded by a rim of contrast material and gas.
SLAP type III is the bucket handle tear of the s...
This is a basic article for medical students and other non-radiologists
Chest x-ray review is a key competency for medical students, junior doctors and other allied health professionals. Using A, B, C, D, E is a helpful and systematic method for chest x-ray review where D refers to disability a...
Chondroblastomas, also referred as Codman tumours, are rare benign cartilaginous neoplasms that characteristically arise in the epiphysis or apophysis of a long bone in young patients. Despite being rare, they are one of the most frequently encountered benign epiphyseal neoplasms in skeletally i...
Distinguishing between a chondroblastoma and an epiphyseal clear cell chondrosarcoma can be difficult. Helpful features which suggest a clear cell chondrosarcoma include:
older age (chondroblastomas tend to occur 10-20 years earlier)
absent adjacent bone oedema
high T2 signal (so...
Although frequently used as a synonym for calcium pyrophosphate dihydrate deposition disease (CPPD), chondrocalcinosis simply means visible calcification of both hyaline cartilage and fibrocartilage.
It has a reported prevalence of 5-15% 2 and is thought to increase with age.
Mnemonics for chondrocalcinosis include:
WHIP A DOG
C: crystals e.g. CPPD, sodium urate (gout)
C: cations e.g. calcium (any cause of hypercalcemia), copper, iron
C: cartilage degeneration (e.g. osteoarthritis, acromegaly, ochronosis)
WHIP A DOG
W: Wilson di...
Chondrodysplasia punctata (CDP) is a collective name for a heterogenous group of skeletal dysplasias. Calcific stippling of cartilage and peri-articular soft tissues is often a common feature.
It can be broadly divided into rhizomelic and non-rhizomelic forms:
Chondroectodermal dysplasia, also known as the Ellis-van Creveld syndrome, is a rare type of skeletal dysplasia. It is classified as a type of mesomelic limb shortening 5.
Clinical features include:
narrowing of thorax with short ribs
small and flared ilia
Chondroid lipomas are rare benign soft tissue tumours that, as you might guess, contain a varied ratio of both fat and cartilage. These lesions can be diagnostically confusing as they may mimic or be confused with other fat containing neoplasms, most importantly those of much greater clinical si...
Chondrolysis, also known as acute cartilage necrosis, is an acute cartilage destruction of the femoral head. It is one of the complications that are specifically associated with slipped capital femoral epiphysis (SCFE). It is a poorly understood phenomenon.
The quoted incidence is...
Chondromalacia patellae refers to softening and degeneration of the articular hyaline cartilage of the patella and is a frequent cause of anterior knee pain.
Tends to occur in young adults. There is a recognised female predilection.
Patients with chondromal...
Chondromyxoid fibromas (CMFs) are extremely rare, benign cartilaginous neoplasms that account for <1% of all bone tumours.
The majority of cases occur in the second and third decades, with ~75% of cases occurring before the age of 30 years 1,12-15. There is no recognised gender ...
Chondrosarcomas are malignant cartilaginous tumours that account for ~25% of all primary malignant bone tumours. They are most commonly found in older patients within the long bones and can arise de novo or secondary from an existing benign cartilaginous neoplasm. On imaging, these tumours have ...
Chondrosarcoma grading allows the division of chondrosarcoma into 3 (sometimes 4) grades.
Grade 1 - low grade
mostly chondroid matrix
little if any myxoid
difficult to distinguish from enchondroma (see enchondroma vs. low grade chondrosarcoma for imaging distinguishing feat...
Chondrosarcomas of the base of the skull are rare compared with other skull base tumours but are an important differential diagnosis as surgical resection and management are affected by the preoperative diagnosis.
Chondrosarcomas of the base of the skull make up only a small fract...
Chopart fracture is a fracture/dislocation of the mid-tarsal joint (Chopart joint) of the foot, i.e. talonavicular and calcaneocuboid joints which separate the hindfoot from the midfoot. The commonly fractured bones are the calcaneus, cuboid and navicular.
The foot is usually dislocated mediall...
There are many signs in radiology that are related to Christmas:
snowcap sign in avascular necrosis
in total anomalous pulmonary venous return
in pituitary macroadenomas
snowstorm appearance in complete hydatidiform and testicular microlithiasis
holly leaf sign in calcified pl...
Chronic exertional compartment syndrome (CECS), previously known as anterior tibial syndrome, is a type of compartment syndrome that is brought on by exercise.
The exact prevalence is not known since sufferers may modify the way they exercise and therefore never present. CECS can ...
Chronic granulomatous disease (CGD) refers to heterogeneous group of inherited immune deficiency disorders characterised by the inability to destroy phagocyted catalase positive bacteria due to lack of NADPH oxidase which results in formation of granulomas in different tissues.
Chronic hip subluxation most common occurs in paediatric patients with neuromuscular disorders (e.g. cerebral palsy). It is considered a form of developmental hip dysplasia.
Chronic hip subluxation occurs in ~45% of cerebral palsy patients who are not walking by 5 years of age 3....
Chronic recurrent multifocal osteomyelitis (CRMO) is an idiopathic inflammatory bone disorder seen primarily in children and adolescents. It is often a diagnosis of exclusion once underlying infection and neoplasia has been ruled out. However, there are some cases in which lesion location and mo...
The circumflex fibular artery is a minor artery of the leg.
Origin and course
Most often arises from the posterior tibial artery, passes laterally round the neck of the fibula through the soleus to anastomose with the lateral inferior genicular, medial genicular and anterior tib...
Clasp-knife deformity is relatively common congenital anomaly found at the lumbosacral junction.
When a clasp-knife deformity is accompanied by pain on extension secondary to protrusion of the enlarged spinous process (knife blade) into the sacral spinal canal, it is called clasp-k...
This classification of gamekeeper's thumb (also known as skier's thumb) was proposed by Hintermann et al. 1 in 1993 and is based on whether a fracture is present and whether the injury is stable:
fracture present, which is non-displaced and stable in flexion
typically treated with a sp...
Classification of proximal femoral deficiency (PFFD) can be complicated and numerous such classifications have been proposed. For a discussion of the condition refer to the article proximal focal femoral deficiency.
One of the simplest and most widely used is that proposed by Aitken 1 which is ...
There are several classification systems for sacral fractures, but the most commonly employed are the Denis classification and subclassification systems, and the Isler classification system. These classification systems are important to understand as proper classification can impact management.
The clavicle (or informally collar bone) is the only bone connecting the pectoral girdle to the axial skeleton and is the only long bone that lies horizontally in human skeleton.
The clavicle is roughly "S-shaped" with a flattened, concave, lateral one-third and a thi...
The clavicle AP cephalic angulation view is a standard projection part of the clavicle series. Often used in conjunction with the AP clavicle, this projection straightens out the clavicle and projects it above overlaying anatomy.
patient is preferably erect
midcoronal plane o...
The clavicle AP view is a standard projection part of the clavicle series. The projection demonstrates the shoulder in its natural anatomical position allowing for adequate radiographic examination of the entire clavicle, as well as the acromioclavicular and sternoclavicular joints of the should...
This is a basic article for medical students and other non-radiologists
Clavicle fracture usually occurs following trauma with a direct blow to the shoulder region, often following a fall.
This is a summary article. For more information, you can read a more in-depth referenc...
The radiographic series of the clavicle is utilised in emergency departments to assess the clavicle, acromioclavicular and sternoclavicular joint.
Clavicle x-rays are indicated for a variety of settings including:
This is a basic article for medical students and other non-radiologists
A clavicle series (or clavicle x-ray) is a set of two images taken of the clavicle to determine whether there is evidence of injury or bony abnormality.
This is a summary article. For more information, y...
Clavicle tumours may be malignant or benign.
osteoma: uncommon, sclerotic, hamartomatous surface lesion
enchondroma: rare, geographic, intramed...
Clavicular fractures are common and account for 2.6-10% of all fractures 2-3. They usually require minimal treatment, which relies on analgesia and a collar-and-cuff. However, in some cases open reduction and internal fixation is required.
Fractures can occur at any part of the clavi...
The clavipectoral fascia is a sheet of loose connective tissue which is the deep layer of fascia in the pectoral region. It acts to suspend the floor of the axilla.
The clavipectoral fascia lies below the clavicular head of the pectoralis major. It fills in the space between the...