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...
Chondrocalcinosis is a descriptive term indicating the presence of gross calcium deposition within articular cartilage, i.e. both hyaline and fibrocartilage.
Chondrocalcinosis articularis was an early term for calcium pyrophosphate dihydrate deposition disease (CPPD) 5, which may e...
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...
Chordomas are uncommon malignant tumours of the axial skeleton that account for 1% of intracranial tumours and 4% of all primary bone tumours.
They originate from embryonic remnants of the primitive notochord (earliest fetal axial skeleton, extending from the Rathke's pouch to the tip of the c...
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...
Clay-shoveler fractures are fractures of the spinous process of a lower cervical vertebra.
Often these injuries are unrecognised at the time and only found incidentally years later when the cervical spine is imaged for other reasons.
Acutely they tend to be associated wi...
Clear cell chondrosarcomas are a subtype of chondrosarcoma constituting 1-2% of all chondrosarcomas. They are typically low-grade (see chondrosarcoma grading) and get their name from the presence of clear cell chondrocytes which contain abundant vacuolated cytoplasm due to the presence of glycog...
Cleft epiphysis is a normal variant of an epiphysis. It can be either unilateral or bilateral. The most common site is the epiphysis of the first proximal phalanx of the foot.
Plain radiographs will demonstrate a lucent defect in the epiphysis. The borde...
Cleidocranial dysostosis (CCD), also known as cleidocranial dysplasia, is a rare skeletal dysplasia with predominantly membranous bone involvement, which carries an autosomal dominant inheritance 4.
large head, with large fontanelles with delayed closure
Clinodactyly is a descriptive term that refers to a radial angulation at an interphalangeal joint in the radio-ulnar or palmar planes. It typically affects the 5th finger.
The estimated incidence is highly variable dependent on sampling and has been reported to range between 1-18...
A cloaca (pl. cloacae/cloacas) can be found in chronic osteomyelitis.
The cloaca is an opening in an involucrum which allows drainage of purulent and necrotic material out of the dead bone. If the tract extends to the skin surface, the portion extending beyond the involucrum to the skin surface...
Closed reduction or manipulation is a common non-invasive method of treating mildly displaced fractures. Usually performed in an emergency department or orthopaedic clinic with light sedation and analgesia, the fracture is manipulated back into anatomic alignment and immobilised with a cast, bra...
Closed reduction-internal fixation, abbreviated to CRIF, refers to the orthopaedic operative management of a fracture (or fracture-dislocation complex) where closed reduction is performed (manipulation) and internal fixation is applied, usually in the form of K-wires to stabilise the fracture.
The Cobb angle is the most widely used measurement to quantify the magnitude of spinal deformities, especially in the case of scoliosis, on plain radiographs. A scoliosis is defined as a lateral spinal curvature with a Cobb angle of 10° or more 4.
To measure the Cobb angle, one mus...
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 (plural: coccyges) is the series of rudimentary vertebrae forming the caudal termination of the vertebral column and is positioned inferior to the apex of the sacrum. The coccyx is one leg of the tripod formed in conjunction with the ischial tuberosities for support in a seated positi...
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 ...
There are several described cockade signs in radiology:
cockade sign (intraosseous lipoma)
cockade sign (aorto-left ventricular tunnel) 1
cockade sign (appendicitis) 2
cockade sign (hypertrophic pyloric stenosis) 3
cockade sign (GI tumours) 4
The cockade sign describes the classic appearance of a calcaneal intraosseous lipoma seen as a well-defined lytic lesion with a central calcification.
History and etymology
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. In a study of 700 chest radiographs, Ben Felson found that 75% had companion shadows on the lower ribs 3.
They appear secondary to soft tissues and intercostal muscles running ...
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 total hip arthroplasty are common and it is essential for the radiologist to be aware of them in the assessment of radiographs of total hip replacements. Complications are many and can occur at various time intervals following the initial surgery:
aseptic loosening: considered ...
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...
A useful mnemonic for remembering cone-shaped epiphysis is:
A: achondroplasia, acrodysostosis
B: beckwith-Wiedemann syndrome
C: chondroplasia punctata, Cockayne syndrome, conorenal syndrome (Mainzer-Saldino Syndrome, associated with chronic renal failure and phalang...
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 a 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 m...
Congenital limb amputation is the absence of a fetal limb or part of a limb that usually occurs due to disruption of vascular supply.
Congenital amputations occur in 0.5 (range 0.03-1) per 1000 live births 2.
They are slightly more common in the upper limb (60%) than ...
Congenital lumbar spinal stenosis is a type of spinal canal stenosis and has a different epidemiology with less severe degenerative change compared to acquired/degenerative lumbar spinal stenosis.
Congenital lumbar spinal stenosis tends to affect patients at a younger age (30-50 ...
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.
Conventional chondrosarcoma also known as central chondrosarcoma is the most common 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 1.5-2:1.
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 suggests the presence of raised intracranial pres...
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 silver skull or 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 r...
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...