Cobb syndrome also called cutaneous vertebral medullary angiomatosis is a metameric vascular malformation that involves all three layers (ectoderm, mesoderm and neural tissue) of the same segmental dermatome.
The importance of this syndrome is the recognition that cutaneous vascular lesions may...
Coccidioidomycosis refers to an infection caused by the dimorphic fungus Coccidioides spp, usually localised to the lungs. This disease is not to be confused with the similarly named paracoccidioidomycosis.
The most common forms of Coccidioides spp are Coccidioides immitis and Coc...
Coccydynia refers to pain in and among the area of the coccyx. It is characterised by coccygeal pain which is typically provocated by pressure. It may remain unclear in origin owing to the unpredictability of the source of pain 1.
No accurate data about the frequency of coccydynia...
The coccygeus, also known as the ischiococcygeus, is a remnant muscle of the pelvic floor.
The coccygeus is a paired muscle which is triangular in shape and overlies the sacrospinous ligament. The coccygeus lies parallel to the inferior border of the piriformis, but is separated ...
The coccyx AP view is used to demonstrate the coccyx, in conjunction with the sacrum and coccyx (lateral view). Follow departmental protocol in relation to imaging this region.
the radiograph is performed with the patient in a supine position, with arms placed comfortably by ...
The cockade sign is a classic appearance of an intraosseous lipoma of the calcaneus which presents as a well-defined lytic lesion with a central calcification resembling a cockade.
It is named after a cockade, which is a badge, usually in the form of a rosette or knot, generally worn on the hat.
Codman triangle is a type of periosteal reaction seen with aggressive bone lesions. With aggressive lesions, the periosteum does not have time to ossify with shells of new bone (e.g. as seen in single layer and multilayered periosteal reaction), so only the edge of the raised periosteum will oss...
COL4A1-related disorders are a group of autosomal dominant disorders caused by a mutation in the COL4A1 gene.
The exact prevalence is unknown, but the group of disorders is considered to be under-recognised, especially asymptomatic variants 1.
The clinical ...
The collateral ligaments of the foot are attached to the dorsal tubercles on the metatarsal heads and the corresponding side of the phalangeal bases.
Colles fractures are very common extra-articular fractures of the distal radius that occur as the result of a fall onto an outstretched hand. They consist of a fracture of the distal radial metaphyseal region with dorsal angulation and impaction, but without the involvement of the articular surf...
Comminuted fractures are fractures where more than 2 bone components are created.
The problem with the term is that it includes a very heterogeneous group of fractures from a 3 part humeral head fracture to a multi-part fracture of the femur following a high-energy road traffic accident.
The common peroneal nerve, also known as common fibular nerve, forms the lateral part of the sciatic nerve and supplies the leg.
origin: one of two terminal branches of the sciatic nerve
course: diverges laterally to enter the lateral compartment of the leg
Companion shadows are smooth, homogeneous, radiopaque shadows running parallel along the bones. They appear secondary to soft tissues and intercostal muscles running along:
inferior border of lower ribs
upper borders of clavicles
Companion shadows need to be diff...
Complete fractures are fractures where the parts of the bone that have been fractured are completely separated from each other. There is complete separation of the cortex circumferentially.
Complete fractures can be classified as:
transverse: straight across the bone
oblique: oblique line acr...
Complex meniscal tears extend in more than one plane, and can in turn create separate flaps of meniscus.
The mensical tear usually includes a combination of radial, horizontal, and longitudinal components (any two or all three). Often the meniscus substance app...
Complex regional pain syndrome (CRPS), also known as Sudeck atrophy, is a condition which can affect the extremities in a wide clinical spectrum.
Two types of CRPS have been described 8:
type 1: no underlying single nerve lesion (formerly known as reflex sympathetic dystrophy)
Complications of hip joint replacements are common and are essential for the radiologist to be aware in the assessment of the radiographs with hip prostheses. They are many and can occur at various time intervals following the initial surgery:
aseptic loosening: considered to be the most common...
Computed bone age measurement refers to the automatic computer analysis of a left hand radiograph in order to estimate accurately bone age in cases of suspected growth delay.
Advanced digital processing of data from automatic computer analysis of the phalangeal/carpal bones and/ or e...
Computed tomography scanogram for leg length discrepancy assessment is performed in patients (children in most of the cases) with suspected inequality in leg length (anisomelia).
obtained images are typically anteroposterior (AP) scout views of the bilateral femurs and tibias
There are many conditions that can involve both skin and bone.
osteolytic bone lesions
basal cell naevus syndrome
langerhans cell histiocytosis
Condylar process fractures are fractures of the condylar process of the mandible. The condylar process of the mandible is involved in around 30% of all mandibular fractures.
Condylar fractures are classified according to the location of the fracture and the direction displacement of the condyle...
Condyloid joints are a type of synovial joint where the articular surface of one bone has an ovoid convexity sitting within an ellipsoidal cavity of the other bone.
Condyloid joints allow movement with two degrees of freedom much like saddle joints. They allow flexion/extension, ab...
Congenital absence of a spine pedicle is a rare congenital condition, but awareness of its characteristic imaging appearance is important to avoid misdiagnosis.
Failure to recognise this entity can lead to misdiagnosis of unilateral facet subluxation/dislocation, leading to unnecessary treatmen...
Congenital anomalies of the posterior arch of the atlas (C1) are relatively common anomalies. They may range from partial defects presenting as clefts to complete absence of the posterior arch (aplasia).
These anomalies are classified according to Currarino (see below). It should not be confuse...
Congenital diaphragmatic herniation (CDH) accounts for a small proportion of all diaphragmatic herniae. However, it is one of the most common non-cardiac fetal intrathoracic anomalies.
Congenital diaphragmatic hernias are seen in 1 of every 2000-4000 live births. 84% are left-side...
Congenital insensitivity to pain (CIP) refers to group of rare hereditary sensory and autonomic neuropathies (HSANs) characterised by an inability to feel pain 1.
Although not clearly defined in the literature, CIP is not one specific diagnosis, but describes symptoms common to man...
Congenital limb amputations are a limb anomaly that usually occur due to disruption of vascular supply.
Congenital amputations occur in 0.5 (range 0.03-1) per 1000 live births 2.
Slightly more common in the upper limb (60%) than in the lower limb (40%) 2.
Congenital lumbar spinal stenosis (CLSS) is a type of spinal canal stenosis and has a different epidemiology with less severe degenerative change compared to acquired/degenerative lumbar spinal stenosis.
CLSS tends to affect patients at a younger age (30-50 years old) than lumbar...
Congenital muscular dystrophies (CMD) are a heterogeneous group of autosomal recessive myopathies presenting at birth with hypotonia, delayed motor development, and early onset of progressive muscle weakness, confirmed with a dystrophic pattern on muscle biopsy.
Congenital pseudoarthrosis of the clavicle is a rare condition, which typically presents as an isolated anatomical variant.
Usually presents as a midclavicular swelling in the neonate or young child 1.
Congenital pseudoarthrosis of the clavicle is more commo...
Congenital pseudoarthrosis of the tibia describes abnormal bowing that can progress to a segment of bone loss simulating the appearance of a joint. The condition is usually apparent shortly after birth and is rarely diagnosed after the age of two.
The aetiology is unclear, however, a...
Congenital radial head dislocation is the most common congenital elbow abnormality. It can occur in isolation, or more commonly may be associated with other conditions or syndromes.
Overall, congenital radial head dislocation is rare 2.
Congenital radial he...
Congenital talipes equinovarus (CTEV) is considered the most common anomaly affecting the feet diagnosed on antenatal ultrasound.
While some use CTEV and clubfoot (CF) synonymously, in certain publications term clubfoot is considered a more general descriptive term that describes t...
The Connolly procedure is performed by an open posterior approach and involves transferring the infraspinatus with a portion of greater tuberosity into the defect, rendering the defect extra-articular; although this procedure restore the stability, it reduces the shoulder range of movement. The ...
The conoid ligament is one of two components forming the coracoclavicular (CC) ligament. The trapezoid ligament is the other component.
The conoid ligament takes the shape of an inverted cone. It is the posteromedial part of the coracoclavicular ligament. Its apex originates from...
The conoid tubercle also known as the coracoid tuberosity (not to be confused with the coracoid process of the scapula) is a bony prominence on the inferior surface of the lateral third of the clavicle.
It marks the insertion of the conoid ligament (which along with the trapezoid ligament) for...
A useful mnemonic to remember the contents of the cubital fossa is, from medial to lateral:
My Brother Throws Rad Parties
M: median nerve
B: brachial artery
T: tendon of biceps
R: radial nerve
P: posterior interosseous branch of radial nerve
Contiguous bone activity is a bone scan phenomenon seen in tumours which incite a regional hyperaemia. Increased activity on blood pool images is seen extending across joints and to adjacent bones. This should not be mistaken for direct tumour involvement.
An example of a tumour which may demo...
Contrast media extravasation (CMEV) refers to the leakage of contrast media from the normal intravascular compartment into surrounding soft tissues; It is a well-known complication of contrast-enhanced CT scanning. It can also occur in MRI studies, but the complications are rare given the low vo...
A contrecoup injury of the knee is a bone contusion of the posterior lip of the medial tibial plateau. It occurs during knee reduction after a pivot shift injury and is highly associated with ACL tears 1, and peripheral tear or meniscocapsular separation of the medial meniscus posterior horn 2.
Conus medullaris syndrome is caused by an injury or insult to the conus medullaris and lumbar nerve roots. It is a clinical subset of spinal cord injury syndromes. Injuries at the level of T12 to L2 vertebrae are most likely to result in conus medullaris syndrome.
The conus medullari...
Conventional chondrosarcoma also known as central chondrosarcoma is the most comon subtype of chondrosarcoma and may be low, intermediate or high grade (see chondrosarcoma grading). They typically occur in the 4th and 5th decades with a slight male predominance 1.5-2.0:1.
Convolutional markings are normal impressions of the gyri on the inner table of the skull, seen predominantly posteriorly. If they are pronounced and over the more anterior parts of the skull, then this is referred to as a copper beaten skull and raises the possibility of raised intracranial pre...
The Cooke and Newman classification of periprosthetic hip fractures is a modification of the Bethea classification proposed several years earlier.
explosion type fracture, comminuted around the stem of the implant
the prosthesis is always loose and the fracture is inherently unstable
Cookie bite metastases are characterised by small focal eccentric lytic external cortical destruction in long tubular bones.
This type of destruction is typically described for metastases from bronchogenic carcinoma, however they can also occur with other tumours.
Copper beaten skull, also known as beaten brass skull, refers to the prominence of convolutional markings (gyral impressions on the inner table of the skull) seen throughout the skull vault.
The appearance of copper beaten skull is associated with raised intracranial pres...
The coracoacromial ligament is a flat triangular band that plays a supportive role for the shoulder joint.
originates from the medial border of the acromion
attaches to the lateral border of the coracoid process
overlies the subacromial bursa
indirectly supports the head of th...
The coracobrachialis is one of the three muscles of the anterior compartment of the arm. It sits beneath the biceps brachii, inserting via a flat tendon into the medial shaft of the humerus.
origin: coracoid process of scapula
insertion: via a flat tendon onto the midportion of the medial surf...
The coracoclavicular (CC) distance is an indicator of the integrity of the coracoclavicular (CC) ligament.
The CC distance is assessed on a frontal radiography of the shoulder or clavicle or the coronal projection or a CT or MRI as the distance between the superior cortex...
The coracoclavicular joint is a normal variant of the pectoral girdle, where the conoid tubercle of the clavicle appears enlarged or elongated, with a flattened inferior surface where it approximates the coracoid process of the scapula to form an articulation.
More common in Asia...
The coracoclavicular (CC) ligament is the major vertical stabilising factor of the acromioclavicular joint.
The coracoclavicular ligament can be divided into two parts, the more medial conoid ligament and trapezoid ligament.
origin: knuckle of the coracoid proc...
Coracoclavicular (CC) ligament injury is common with shoulder trauma. It is considered part of the spectrum of acromioclavicular joint injuries 2 and is not often an isolated injury. It is also often injured with clavicular fractures.
This injury is easy to miss, especially with presence of an...
The coracohumeral ligament (CHL) is a strong supportive ligament of the shoulder joint and is a part of rotator cuff interval.
originates from the lateral surface of the base of the coracoid process
runs laterally across the glenohumeral capsule and covers the long head of bicep...
The coracoid process is an anteriorly projecting hook-like process on the superolateral edge of the scapula that projects anterolaterally.
coracobrachialis from the medial apex
short head of biceps brachii from the lateral apex
pectoralis minor from the m...
Coracoid process fractures are an uncommon type of scapular fracture. They do not often occur in isolation and are often associated with acromial, clavicular, or scapular fracture, as well as humeral head dislocation.
In general, the coracoid process tends to fracture at its base and be minimal...
The corduroy sign refers to vertically-oriented, thickened trabeculae seen in intraosseous haemangiomas of the spine. It is the sagittal/coronal equivalent of the polka-dot sign seen on axial imaging.
It is caused by the replacement of the normal cancellous bone by thickened vertical trabecula...
Coronal balance is one of the features that needs to be assessed on long spine radiographs obtained for spinal deformity, particularly scoliosis. It measures whether or not the upper spine is located over the midline (normal) or off to one side.
To assess coronal balance, a vertical (plumb) li...
Coronal vertebral cleft refers to the presence of a radiolucent vertical defect on a lateral radiograph.
It is most often seen in premature male infants 1,3. As they can occur as part of normal variation (especially in the lower thoracic-upper lumbar spine of premature infants) ...
Coronoid process can refer to a number of different anatomical structures:
coronoid process (mandible)
coronoid process (ulna)
Fractures of the coronoid process of the ulna are uncommon and often occur in association with elbow dislocation.
Fracture of the coronoid process is thought to result from elbow hyperextension with either avulsion of the brachialis tendon insertion, or shearing off by th...
Corpectomy refers to removal of one or more vertebral bodies to treat compressive myelopathy caused by extensive hypertrophic osteoarthritis. In most cases, the intervertebral discs are removed as well. It is most commonly performed for degenerative cervical myelopathy; however, thoracic and lum...
The corrugator supercilii are two small, triangular muscles that allow facial expression through movement of the eyebrows, including frowning. They originate from the medial end of the supraorbital margins and insert deep to and can cause traction on the skin over the middle of the supraorbital ...
The outer shell of compact bone is called cortical bone or cortex.
Cortical bone contains Haversian systems (osteons) which contain a central Haversian canal surrounded by osseous tissue in a concentric lamellar pattern.
Two fibrovascular layers surround the cortical bone which...
Cortical desmoids, also known as cortical avulsive injuries or the Bufkin lesion, are a benign self-limiting entity. This is a classic "do not touch" lesion, and should not be confused with an aggressive cortical/periosteal process (e.g. osteosarcoma).
Cortical desmoid is a misnom...
Costal cartilage fractures are fractures of the cartilage connecting the ribs anteriorly to the sternum.
There is little published data on costal cartilage fractures. Most reported cases are in males and resulted from blunt trauma or a fall 1-2.
In young ch...
The costochondral joints are the joints between each rib and its costal cartilage. They are primary cartilaginous joints. These joints represent the demarcation of the unossified and ossified part of the rib 1. The joint is held together by periosteum, with the lateral aspect of the costal ca...
The costoclavicular ligament or rhomboid ligament is the major stabilising factor of the sternoclavicular joint.
The costoclavicular ligament binds the inferior medial clavicle (via the rhomboid fossa) to the first costal cartilage and adjacent end of the first rib. It is compose...
The costovertebral joint is an articulation between the ribs and the vertebral column.
The ribs articulate with the thoracic vertebrae via two distinctly different joints:
costovertebral joint - articulation between the head of the rib and the vertebral body
The costoxiphoid ligaments, also known as the chondroxiphoid ligaments, are inconstant fibrous structures joining the anterior and posterior surfaces of the xiphoid to the respective surfaces of the adjacent seventh and, occasionally, sixth costal cartilages.
The cotton wool appearance is a plain film sign of Paget disease and results from thickened, disorganized trabeculae which lead to areas of sclerosis in a previously lucent area of bone, typically the skull. These sclerotic patches are poorly defined and fluffy.
Other Paget disease re...
Cowden syndrome, also known as multiple hamartoma syndrome, is characterised by multiple hamartomas throughout the body and increased risk of several cancers.
Type 2 segmental Cowden syndrome is the association of Cowden syndrome with a Cowden naevus, when it is considered a type o...
Coxa magna is the asymmetrical, circumferential enlargement and deformation of the femoral head and neck. Definitions in the literature vary but enlargement with asymmetry >10% in size is a reasonable cut-off for diagnosis 1.
Coxa plana is flattening of the femoral head epiphysis and is associated with many skeletal disorders:
multiple epiphyseal dysplasia
haemoglobinopathies, e.g. sickle cell ana...
Coxa profunda refers to a deep acetabular socket. On pelvis x-rays it is seen as the acetabular fossa being medial to the ilioischial line. It should be differentiated from protrusio acetabuli, where the femoral head is seen additionally medial to the ilioischial line. Coxa profunda is much more...
Coxa valga describes a deformity of the hip where there is an increased angle between the femoral neck and femoral shaft.
Coxa valga is often associated with shallow acetabular angles and femoral head subluxation.
neuromuscular disorders, e.g. cerebral palsy
Coxa vara describes a deformity of the hip where the angle formed between the head and neck of the femur and its shaft (Mikulicz angle) is decreased, usually defined as less than 120 degrees.
It can be congenital or acquired. The common mechansim in congenital cases is a failure of m...
Cozen fracture or phenomenon is the valgus angulation deformity of the tibia following a proximal tibial metaphyseal fracture in children.
This typically occurs as a late deformity in children aged 3-6 years.
Proposed causes include:
non-recognised or under...
Craniofacial fibrous dysplasia is one of four types of fibrous dysplasia and is characterised, as the name suggests, by involvement of the skull and facial bones.
For a general discussion of the underlying pathology, refer to the parent article fibrous dysplasia.
Although the term...
Craniosynostosis refers to premature closure of the cranial sutures. The skull shape then undergoes characteristic changes depending on which suture(s) close early.
There is a 3:1 male predominance.
Primary forms are either sporadic or familial. Secondary craniosynosto...
Craniotabes is defined as a softening of the skull bones that may be normally present in newborns.
Craniovertebral junction (CVJ) anomalies can be congenital, developmental or due to malformation secondary to any acquired disease process. These anomalies can lead to cranial nerve compression, vertebral artery compression and obstructive hydrocephalus.
The cranio-vertebral junctio...
The crescent sign of avascular necrosis is seen on conventional radiographs and refers to a linear area of subchondral lucency seen most frequently in the anterolateral aspect of the proximal femoral head (which is optimally depicted on the frog-leg radiographic view). It indicates imminent arti...
CREST syndrome is a variant of progressive systemic sclerosis (PSS) and stands for
C - Calcinosis
R - Raynaud phenomenon
E - oEsophageal dysmotility
S - Sclerodactyly
T - Telangiectasia
The critical zone of the rotator cuff is an area approximately 8-15 mm from the insertion of the rotator cuff tendons onto the greater tubercle of the humeral head, mainly within the supraspinatus tendon. This is a watershed zone between the anterior and posterior circumflex humeral, thoracoacro...
The crossing sign is seen on true lateral plain radiographs of the knee when the line of the trochlear groove crosses the anterior border of one of the condyle trochlea. It is a predictor of trochlear dysplasia. Trochlear dysplasia has been linked to recurrent patellar dislocation 1,2,4. The cro...
Crouzon syndrome is rare disorder characterised by premature craniosynostoses.
abnormal calvarial shape: in severe case can give a "cloverleaf skull"
shallow orbits with exopthalmos
mid facial hypoplasia
It carries an autosomal dominant ...
The crowned dens syndrome is an inflammatory condition resulting from crystal deposition in cruciform and alar ligaments surrounding the dens, appearing as a radiopaque 'crown' surrounding the top of the dens. It typically presents with pain and increased inflammatory markers.
The cruciate ligament of the atlas (also known as the cruciform ligament) is an important ligamentous complex that holds the posterior dens of C2 in articulation at the median atlantoaxial joint. It lies behind a large synovial bursa (surrounded by loose fibrous capsule) and consists of two band...
Crystal arthropathies are a group of joint disorders due to deposition of crystals in and around joints which lead to joint destruction and soft tissue masses.
The most common arthropathies are:
gouty arthropathy due to monosodium urate (MSU) deposition
pseudogout due to calcium py...
The C sign is an important radiological sign which may be seen on a lateral radiograph of the ankle in those with the talocalcaneal subtype of tarsal coalition.
A continuous C-shaped arc on a lateral ankle radiograph is formed by the medial outline of the talar dome an...
The cubital fossa is a triangular space which forms the transition between the arm and the forearm. It is located anterior to the elbow joint.
superior: the line joining the medial and lateral humeral epicondyles
lateral: medial border of brachioradialis
The cubital tunnel is a space through which the ulnar nerve passes posterior to the medial epicondyle of the humerus.
cubital tunnel retinaculum (a.k.a. ligament or band of Osborne), extends from the olecranon to the medial epicondyle
anconeus epitrochlearis (...
Cubital tunnel syndrome is a type of ulnar nerve compression neuropathy which can occur from a pathological compression of the ulnar nerve at the cubital tunnel.
It is the second most common peripheral neuropathy of the upper extremity 1,3.
Ulnar nerve comp...