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 images in the cervical spine series and are always done bilaterally for comparison purposes. However, the PA oblique projection is preferred as it reduces radiation dose to the thyroid 1 co...
The cervical spine flexion and extension views demonstrate the seven vertebrae of the cervical spine when the patient is in a lateral position.
These views are specialized projections often requested to assess for spinal stability.
Note: Such functional views should not be perform...
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.
Males are affected more commonly than females with the median age of injury being 56 years. Falls, motor vehicle collisions, pedestrian accidents, cyclin...
The closed mouth odontoid AP view (Fuchs view) is a non-angled AP radiograph of C1 (atlas) and C2 (axis).
This view focuses primarily on the odontoid process, and is useful in visualizing odontoid and Jefferson fractures. The standard Fuchs view (Figure 1 & 3) should not be used i...
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.
As technology advances, computed tomography (CT) has replaced this projection, yet there remain many institutions (especially in rural areas) where CT is not readily available.
This projection helps to vis...
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).
This view focuses primarily on the odontoid process, and is useful in visualizing odontoid and Jefferson fractures.
patient positioned erect in AP position unless trauma the patient...
The PA oblique cervical spine projections are supplementary views to the standard AP, odontoid and lateral images in the cervical spine series and are always done bilaterally for comparison purposes. The PA oblique projection is preferred as it reduces radiation dose to the thyroid 1, compared t...
The cervical spine checklist is just one of the many pathology checklists that can be used when reporting to ensure that you always actively exclude pathology that is commonly missed; this is particularly helpful in the examination setting, e.g. the FRCR 2B rapid-reporting.
The cervical split is a horizontal lucent line over the cervical body seen on the lateral cervical spine projection, simulating a fracture, observed in the context of proliferative osteophytes of the articulation of the uncinate process 1.
In the context of trauma, the c...
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 (lepro...
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...
Chemical shift artifact or misregistration is a type of MRI artifact. It is a common finding on some MRI sequences and used in MRS. This artifact occurs in the frequency-encoding direction and is due to spatial misregistration of fat and water molecules.
Chemical shift is due to the difference...
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...
The chevron sign refers to an inverted V-shape 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. Focal delamination is sometimes termed a carpet lesion 6.
Chondral fissures are a type of chondral injury more accurately cracks or crevices of cartilage extending from the articular surface to the deeper chondral layers. They usually develop as a result of high compressive forces 1 and are often found in the patellar or trochlear cartilage. On MRI the...
Chondral fractures are fractures that involve the cartilage only unlike osteochondral fractures where the articular cartilage, as well as the subchondral bone plate, are involved 1.
Chondral fractures typically occur in combination with ligamentous injuries in young adults but can...
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...
Chondrolabral separation refers to a form of chondrolabral injury, where the labrum is separated from the adjacent cartilage at the articular margin.
Chondrolabral separation is referred to as a chondrolabral injury seen in the hip. It can also occur in the shoulder joint, but simi...
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 of the musculoskeletal system is the pathological degeneration of articular hyaline cartilage in the absence of osteoarthritis 1.
modified Outerbridge grading of chondromalacia
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 ankle instability refers to an unstable ankle joint due to repetitive occasions of ankle instability with concomitant symptoms persisting for longer than one year after an initial ankle injury.
Ankle injuries are common and not only as a sports injury 1-4. They have a high...
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 a heterogeneous group of inherited immune deficiency disorders characterized by the inability to destroy phagocytosed catalase-positive bacteria due to a 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 have been ruled out. However, there are some cases in which lesion location and m...
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...
There are several musculoskeletal complications that can arise in the setting of cirrhosis 1:
stigmata of portal hypertension, mainly abdominal wall varices
hemorrhagic complications due to coagulopathy:
spontaneous rectus hematoma
postparacentesis abdominal wall bleeding
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 the human skeleton.
The clavicle is roughly "S-shaped" with a flattened, concave, lateral...
The clavicle AP cephalic angulation view is a standard projection part of the clavicle series and is often used in conjunction with the AP clavicle view.
This projection straightens out the clavicle and projects most of it above the scapula and second and third rib. It can help to d...
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.
The AP clavicle is often indicated in patients with suspecte...
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 ~5% (range 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.
Clavicular fractures are mo...
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 (Modic type 1): well-defined, paired band-like regions of restricted diffusion affecting two contiguous vertebral bodies, resembling a claw surrounding the disc space on sa...
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...
Cleavage tears of the rotator cuff are delaminated rotator cuff tears characterized as horizontal intratendinous splits between the articular and bursal layers along the tendon filled with fluid.
Intratendinous delaminations seem to be common in articular-sided and bursal-sided te...
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
The cliff sign in hip microinstability is a steep drop-off and loss of normal sphericity of lateral femoral head.
Shenton line distortion
subluxation of the femoral head
sclerosis of the femoral neck
<3 mm anterior lateral capsule
>5 mm anterior...
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, often 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 fractu...
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...
Coaptation refers to a joining or reuniting of two surfaces. This can be in the setting of ends of a broken bone or the edges of a wound or edges of a valve.
Coarse trabecular bones can result from a number of causes. They include:
Paget disease (bone)
hemaglobinopathies, e.g. thalassemia
Coarse trabecular pattern in bone (mnemonic)
A mnemonic to remember differentials causing a coarse trabecular pattern in the bone
P: Paget disease (bone)
H: Hemoglobinopathies (i.e thalassemia), hyperparathyroidism
O: Osteoporosis, osteomalacia
G: Gaucher's disease
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. Scoliosis is defined as a lateral spinal curvature with a Cobb angle of >10° 4. A Cobb angle can also aid kyphosis or lordosis assessment...
Cobb syndrome, also called cutaneous vertebral medullary angiomatosis, or spinal arteriovenous metameric syndrome, consists of the presence of a vascular nevus with a spinal vascular malformation of the same body somite (metamere).
The importance of this syndrome is the recognition that cutane...
Coccidioidomycosis refers to an infection caused by the dimorphic fungus Coccidioides spp, usually localized 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 characterized 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...