The Catterall classification of Perthes disease 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 l...
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 useful mnemonic for remembering the causes of cone-shaped epiphysis is:
A: achondroplasia, acrodysostosis
B: Beckwith-Wiedemann syndrome
C: chondroplasia punctata, Cockayne syndrome, conorenal syndrome, cleidocranial dysplasia, cartilage-hair hypoplasia
A mnemonic for remembering the symmetric vs asymmetric causes of sacroiliitis is:
P: psoriatic arthritis
A: ankylosing spondylitis
I: inflammatory bowel disease related
R: reactive (e.g. Reiter syndrome)
The outside letters P & R (letters are far apart) are the asymmetric ca...
Cavernous venous malformation, also traditionally referred to as a cavernous hemangioma (despite it not being a tumor) 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 appearance can refer to the following:
celery stalk anterior cruciate ligament
celery stalk metaphysis
Celery stalk metaphysis refers to a plain film appearance of the metaphyses in a number of conditions characterized 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 fibers are separated from each other by higher signal mucinous material, best appreciated ...
Cellulitis (rare plural: cellulitides) is an acute infection of the dermis and subcutaneous tissues. It results in pain, erythema, edema, and warmth. Since the epidermis is not involved, cellulitis is not transmitted by person-to-person contact.
Cellulitis can affect any ...
Cenani-Lenz syndactyly (CLS) is a very syndrome primarily characterized by:
syndactyly/oligodactly: syndactyly is often complete and gives a spoon hand type appearance
It carries an autosomal recessive inheritance.
It was first described...
Central osteophytes, also known as subchondral or button osteophytes, are located within the joint and are thought to arise from endochondral ossification of a cartilaginous lesion 1-3.
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...
Cerclage wire refers to a type of orthopedic fixation/stabilization wire placed to approximate fractured bone fragments.
full - 360° circumferential wire used in diaphysis segments of long bones
hemicerclage - wire is placed through one of the main fractured bone fragments, as used in 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 disease 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 mo...
The cervical spine (often shortened to C-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 po...
The AP oblique cervical spine projections are supplementary views to the standard AP, odontoid and lateral c-spine series. It can be taken either as an anterior oblique or posterior oblique projection.
patient is standing erect with either the left or right posterior side clos...
Cervical spine flexion-extension lateral views are specialized 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 characterized 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 PA oblique cervical spine projections are supplementary views to the standard AP, Odontoid and lateral c-spine series. It can be taken either as an anterior oblique or posterior oblique projection. This projection can be used to visualize the intervertebral foramina.
The term cervical stenosis can refer to:
stenosis of the uterine cervix
bony cervical canal stenosis (cervical spinal stenosis)
Chalk stick, also known as 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) 3.
They usually occur through the...
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 recognize 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 joint or Charcot (neuro/osteo)arthropathy, 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 jo...
The causes of a Charcot joint can be remembered, using a mnemonic - with a little poetic license - as they (all) start with the letter S.
s: sugar (diabetes)
s: steroid use
s: spinal cord injury
s: spina bifida
s: scaly disease (l...
Charm needles or "susuk" are talismans alleged to be made of gold or other precious metals, which are inserted into the soft tissue of the body. They are believed to enhance beauty, youth, health and fortune.
This practice is found among women of Southeast Asian countries, commonl...
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 in two different scenarios:
Cheerio sign (pulmonary nodule)
Cheerio sign (shoulder)
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...
Chest wall lipomas are benign fat containing thoracic lesion.
While they can occur at any age, they typically occur in older patients who are 50-70 years of age, and they are most frequent in those with increased an increased body mass index.
They are well-circumscrib...
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...
Chevron deformity refers to an inverted V shaped sign noted in children with achondroplasia. It is most commonly seen in the epiphysis of distal femur and tends to disappear with age 1,2.
Chikungunya fever is caused by the chikungunya virus (CHIKV), and is characterized by a classic viral prodrome of fever, skin exanthem, malaise and arthralgia. Its most striking manifestation is a marked, often fairly debilitating arthritis.
Chondral delamination is a form of cartilage injury and refers to the separation of the articular cartilage from the underlying subchondral bone at the tidemark. It may or may not be associated with chondral fissure.
Often associated with twisting or traumatic shearing stress to the ...
Chondroblastomas, also referred as Codman tumors, 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 im...
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 edema
high T2 signal (sol...
Chondrocalcinosis (plural: chondrocalcinoses) 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 d...
Mnemonics for chondrocalcinosis include:
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)
H: hyperparathyroidism, hyp...
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 tumors 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 sig...
Chondrolysis, also known as acute cartilage necrosis, represents acute cartilage destruction of the femoral head. It is one of the complications that are specifically associated with slipped capital femoral epiphysis (SCFE). It may also be associated with infection, specifically septic arthritis...
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 recognized female predilection.
Patients with chondromal...
Chondromyxoid fibromas (CMFs) are extremely rare, benign cartilaginous neoplasms that account for <1% of all bone tumors 1.
As with all rare lesions, reported epidemiology varies:
most commonly diagnosed before 30 years of age (~75%), mostly during second and third decades...
Chondrosarcomas are malignant cartilaginous tumors that account for ~25% of all primary malignant bone tumors. 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 tumors have rin...
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 tumors 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 fracti...
Chopart fracture-dislocations occur at the midtarsal (Chopart) joint in 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 medially and superior...
Chordomas are uncommon malignant tumors of the axial skeleton that account for 1% of intracranial tumors and 4% of all primary bone tumors.
They originate from embryonic remnants of the primitive notochord (earliest fetal axial skeleton, extending from the Rathke's pouch to the tip of the cocc...
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 characterized 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 pediatric 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...
Circumduction is the orderly combination of shoulder movements so that the hand traces a circle and the arm traces a cone. In order it is produced by shoulder flexion, abduction, extension and abduction (or the reverse).
It is hence produced by co-ordination of all the muscles that produce thes...
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, also colloquially known as the collarbone, 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...
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 utilized 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 tumors may be malignant or benign.
osteoma: uncommon, sclerotic, hamartomatous surface lesion
enchondroma: rare, geographic, intramedu...
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 are required.
Mechanisms of injury
Fractures can occur ...
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...
The claw sign on diffusion weighted imaging refers to a pattern of hyperintensity seen in degenerative changes in the spine. The presence of the claw sign makes spondylodiskitis less likely.
the sign appears as well-defined paired regions of restricted diffusion...
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 fracture (antonyms: compound or open fracture) refers to a fracture or dislocation in which the skin remains intact, i.e. there is no contact between the bone and the external environment.
Closed reduction or manipulation is a common non-invasive method of treating mildly displaced fractures. Usually performed in an emergency department or orthopedic clinic with light sedation and analgesia, the fracture is manipulated back into anatomic alignment and immobilized with a cast, brac...
Closed reduction-internal fixation, abbreviated to CRIF, refers to the orthopedic 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 stabilize the fracture.
A coalition is a joining of two bones that are normally discrete 1. It is usually a congenital abnormality. The bridge between the bones is initially fibrous, then gradually becomes cartilaginous, finally ossifying. Symptoms tend to arise as the coalition forms a synostosis, which is usually fro...