The seventh cervical vertebra, C7, also known as the vertebra prominens, shares similar characteristics of the like typical cervical vertebra C3-C6, but has some distinct features making it one of the atypical vertebrae. The name vertebra prominens arises from its long spinous process, which is ...
Café au lait spots are a type of pigmented skin lesions which are classically described as being light brown in color.
Conditions associated with them include:
neurofibromatosis type 1 (NF1)
McCune-Albright syndrome: typically irregular which has been likened to t...
Caffey disease or infantile cortical hyperostosis is a largely self-limiting disorder which affects infants. It causes bone changes, soft-tissue swelling, and irritability.
It is distinct from physiological periostitis which can be seen involving the diaphyses of the tibiae, humeri, and femora ...
Calcaneal apophysitis, also known as Sever disease, is the painful inflammation of the apophysis of the calcaneus.
It typically presents in active young children and adolescents, especially those who enjoy jumping and running sports.
High plantar foot pressures are...
Calcaneal fractures are the most common tarsal fracture and can occur in a variety of settings.
The calcaneus is the most commonly fractured tarsal bone and accounts for about 2% of all fractures 2 and ~60% of all tarsal fractures 3.
Calcaneal fractures can be divided ...
The calcaneal inclination angle (also known as the calcaneal pitch) is drawn on a weight-bearing lateral foot radiograph between the calcaneal inclination axis and the supporting horizontal surface.
It is a measurement that reflects the height of the foot framework, but is affected by abnormal ...
The calcaneal inclination axis is drawn between the most inferior portion of the calcaneal tuberosity and the most distal and inferior point of the calcaneus at the calcaneocuboid joint on a weightbearing lateral foot radiograph.
It can be used to draw the calcaneal inclination angle.
A mnemonic for calcaneal lesions is:
B: bone cyst (unicameral)
I: intraosseous lipoma
G: ganglion (intraosseous)
G: giant cell tumor
The calcaneal tendon, commonly known as the Achilles tendon, is the strongest and largest tendon of the human body. It is also one of the commonest tendons to become injured due to its high biomechanical load but poor vascularity 2.
The calcaneal tendon forms by the merging of fi...
Avulsion fractures of the calcaneal tuberosity are rare, accounting for only 3% of all calcaneal fractures.
There are three mechanisms of action 4:
fall during plantarflexion
feet fixed on the ground with sudden muscular contraction
There is a s...
Calcaneal vascular remnant is a benign finding that may be seen on MRI of ankle and can be misinterpreted as an alarming bone lesion. It is typically located at the insertion site of sinus tarsi ligaments (cervical and interosseous ligaments).
The focus of signal alteration is believed to be pr...
The calcaneocuboid joint is part of the mid-tarsal (Chopart) joint. It is a synovial articulation between the calcaneus and the cuboid bones of the foot.
The calcaneocuboid joint involves the anterior surface of the calcaneus and the posterior surface of the cuboid. Its joint cap...
The calcaneofibular ligament (CFL) is the middle ligament of the lateral collateral ligament complex of the ankle and stabilizes both the ankle and subtalar joints.
The CFL is an extracapsular round cord measuring 20-25 mm long x 6-8 mm width. Its origin is distal to the anterior...
Calcaneofibular ligament injuries typically occur in conjunction with an anterior talofibular ligament injury within the scope of a lateral ankle sprain and are rarely found isolated. The injuries can comprise either ligament tears, avulsion fractures or both.
The calcaneofibular ...
Calcaneonavicular coalition is one of the two most common subtypes of the tarsal coalition, the other being talocalcaneal coalition. As with any coalition it may be osseous (synostosis), cartilaginous (synchondrosis) or fibrous (syndesmosis).
This type of coalition is mor...
The calcaneus, also referred to as the calcaneum, (plural: calcanei or calcanea) is the largest tarsal bone and the major bone in the hindfoot. It articulates with the talus superiorly and the cuboid anteriorly and shares a joint space with the talonavicular joint, appropriately called the taloc...
The calcaneus axial view is part of the two view calcaneus series assessing the talocalcaneal joint and plantar aspects of the calcaneus.
As technology advances, computed tomography (CT) has widely been used 1 to better visualize and characterize calcaneum fragment displacements and fracture li...
The calcaneus lateral view is part of the two view calcaneus series; this projection is used to assess the calcaneus, talocrural, talonavicular and talocalcaneal joint.
As technology advances, computed tomography (CT) has widely been used 1 to better visualize and characterize calcaneum fragmen...
The calcaneus series is comprised of a lateral and axial (plantodorsal) projection. The calcaneus is the most commonly fractured tarsal bone accounting for ~60% of all tarsal fractures 1. This series provides a two view investigation of the calcaneus alongside the talar articulations and talocal...
This is a basic article for medical students and other non-radiologists
A calcaneus x-ray, also known as calcaneus series or calcaneus radiograph, is a set of two x-rays of the calcaneus. It is performed to look for evidence of injury (or pathology) affecting the leg, often after trauma.
The calcar femorale is a normal ridge of dense bone that originates from the postero-medial endosteal surface of the proximal femoral shaft, near the lesser trochanter. It is vertical in orientation, and the ridge projects laterally toward the greater trochanter. This ridge of bone provides mech...
Calcific bursitis is the result of deposition calcium hydroxyapatite crystals. It is closely related to calcific tendinitis, and many authors refer to them as being the same condition.
Calcific myonecrosis refers to a rare post-traumatic phenomenon. It characterized by the latent formation of a dystrophic calcified mass occurring almost exclusively in the lower limb (it has been occasionally reported at other sites 5).
Plain radiographs typi...
Calcific tendinitis (or calcific tendonitis) is a self-limiting condition due to the deposition of calcium hydroxyapatite within tendons, usually of the rotator cuff. It is a common presentation of the hydroxyapatite crystal deposition disease (HADD).
Typically this condition aff...
Calcific tendinitis of the longus colli muscles is an inflammatory/granulomatous response to the deposition of calcium hydroxyapatite crystals in the tendons of the longus colli muscle. It is sometimes more generically known as calcific prevertebral tendinitis or, less accurately, as retropharyn...
Calcified intra-articular lesions have a relatively limited differential, including:
impaction fracture fragments
intraarticular avulsion fractures
Calcifying aponeurotic fibromas are superficial benign potentially recurrent fibroblastic soft tissue tumors usually seen in the palms and soles of children and adolescents.
Calcifying aponeurotic fibroma is also known as juvenile aponeurotic fibroma or just aponeurotic fibroma 1,2...
Calcinosis circumscripta is a condition involving calcium deposition in the skin and subcutaneous tissues predominantly around joints and extremity 6. It is considered a localized form of calcinosis cutis most often seen in the hands and feet.
Patients present with firm w...
Calcinosis cutis is the term used for the deposition of calcium salts in the skin and subcutaneous tissues.
It is classified according to etiology as 1:
dystrophic (most common): characterized by normal serum calcium and phosphorus, an underlying disease process induces tissue damag...
Calcinosis universalis is a condition characterized by long bands or sheets of symmetrical calcifications in skin, subcutaneous tissues, muscles and tendons 5. It is considered a diffuse form of calcinosis cutis.
It usually presents <20 years of age, and is more common in...
Calcium pyrophosphate dihydrate disease (CPPD), also known as pyrophosphate arthropathy or pseudogout, is defined by the co-occurrence of arthritis with evidence of CPPD deposition within the articular cartilage.
The terminology regarding CPPD disease has been confusing, with chon...
Calvarial thinning can result from many causes. They include:
craniofacial syndromes 1
focal calvarial thinning
Cam morphology refers to an abnormal morphology of the femoral head-neck junction interlinked with an osseous asphericity. It is one possible causes for femoroacetabular impingement.
Cam morphology is also commonly referred to as 'cam deformity', 'cam lesion' or 'cam abnormality', ...
Campomelic dwarfism, also known as campomelic dysplasia, is a rare form of skeletal dysplasia.
Campomelic dwarfism is rare with an estimated incidence of ~1:200,000 births.
genital malformations: may be present in ~66% of patients 6
Camptocormia (bent spine syndrome or cyphose hystérique) is a rare syndrome characterized by involuntary flexion of the thoracolumbar spine with weight-bearing which reduces when laying down, and is due to isolated atrophy of the paraspinal muscles.
In a small case series (n=16), ...
Camptodactyly is a clinical or imaging descriptive term where there is a flexion contracture (usually congenital). Classically this occurs at the proximal interphalangeal joint of the little finger of the hand, although any finger may be affected.
Prevalence ~1%; one-third unilate...
Camptodactyly arthropathy coxa vara pericarditis (CACP) syndrome is a rare condition principally characterized by
congenital or early-onset camptodactyly and childhood-onset non-inflammatory arthropathy
coxa vara deformity or other dysplasia associated with progressive hip disease
Camurati-Engelmann disease, also known as progressive diaphyseal dysplasia, is a rare autosomal dominant sclerosing bone dysplasia. It begins in childhood and follows a progressive course.
Common symptoms include extremity pain, muscle weakness, cranial nerve impairment a...
Canadian C-spine rules are a set of guidelines that help a clinician decide if cervical spine imaging is not appropriate for a trauma patient in the emergency department. The patient must be alert and stable.
There are three rules:
is there any high-risk factor present that requires cervical s...
Cancellous, trabecular or spongy bone is one of the two macroscopic forms of bone, the other being cortical bone, and comprises 20% of skeletal mass.
Cancellous bone is located in the medullary cavity of bone, in particular tubular and short bones, and consists of dense trabecul...
The capitate, also known as the os magnum, is the largest of the carpal bones and sits at the center of the distal carpal row. A distinctive head-shaped bone, it has a protected position in the carpus, and thus isolated fractures are unusual.
The capitate sits in a p...
Capitate fractures are an uncommon carpal fracture. They rarely occur in isolation and are often associated with greater arc injuries.
Capitate fractures account for 1-2% of all carpal fractures 1,2. It is the second most common carpal bone injury in children 1.
Capitellum fractures are uncommon, but their prompt diagnosis and management are crucial due to the severity of the consequent functional impairment resulting from these intra-articular elbow fractures.
Capitellar fractures are relatively rare, with approximately 3-4% of distal h...
Capitohamate coalition is the second most common type of carpal coalition and represents the congenital fusion of the capitate and the hamate. It represents ~5% of all carpal fusions 1 and is associated with Apert syndrome 2.
The capitolunate angle is the angle between the long axis of the capitate and the mid axis of the lunate on the sagittal imaging of the wrist. In a normal situation it should be less than 30° in the resting (neutral) position.
The angle is increased in carpal instability such as with a dorsal i...
Capsulolabral insertion classification reflects the variation in the relationship between the glenoid labrum and the anterior shoulder joint capsule.
type 1: capsule inserts into the labrum proper
type 2: capsule inserts into the base of the labrum, or within 1 cm of the base
Carcinogens are substances known to cause cancer. They include:
Nasopharynx / nasal passage
ionizing radiation (not technically a substance)
polyaromatic hydrocarbons (PAH)
The carotid tubercle is a commonly used term referring to the paired anterior tubercles of the transverse processes of the sixth cervical vertebrae 1. The carotid tubercle serves as an important landmark with respect to performing regional anesthesia such as a brachial plexus and cervical plexus...
Carpal angle is defined by two intersecting lines, one in contact with the proximal surface of the scaphoid and the lunate and the other line through the proximal margins of the triquetrum and the lunate. Its normal value is between 130° and 137°.
It is increased (>139°) in:
Carpal bone fractures comprise a range of different fractures which carry varying outcomes. They can involve one or a combination of carpal bones and also be part of fracture-dislocations.
Individual fractures include
scaphoid fracture: 50-80%
lunate fracture: 3.9%
triquetral fracture: ~18%
The carpal bones are the eight bones of the wrist that form the articulation of the forearm with the hand. They can be divided in two rows:
The names and order of these bones can be rememb...
Mnemonics of the carpal bones are numerous and useful for memorizing the order and location of the bones.
Some mnemonics name the carpal bones in a circle, starting with the proximal row from the scaphoid towards the pinky (small finger) and then the distal row starting from the hamate towards ...
The carpal boss is a hypertrophied bony protuberance on the dorsal surfaces of the base of the second or third metacarpals, near the capitate and trapezium. It may be bilateral.
The condition may represent one or more of:
degenerative osteophyte formation
os styloideum (an accessor...
Carpal coalition refers to failure of separation of two or more carpal bones, and although the most commonly involved bones are the lunate and triquetrum, most combinations of adjacent bones can be found to be coalesced.
Carpal fusion is a misnomer, as it is the failure of normal ...
Carpal height is used to diagnose and assess the severity of carpal collapse. It is defined as the distance between the base of third metacarpal and the subchondral bony cortex of the distal radius. But due to variations between individuals, it is more appropriate to calculate the carpal height ...
Carpal instability refers to the inability of the wrist to maintain its structural stability under physiologic movements and loading forces ultimately leading to derangement of the carpal bones with associated malalignment.
Clinical conditions associated with carpal ...
The carpal tunnel is a fibro-osseous canal in the anterior (volar) wrist that acts as a passageway for structures between the forearm and the anterior hand.
superficial border (roof): flexor retinaculum
deep border (floor): carpal groove (formed by palmar aspect of c...
Carpal tunnel syndrome results from compression of the median nerve (tunnel syndrome) within the carpal tunnel. It is a cause of significant disability and is one of three common median nerve entrapment syndromes, the other two being anterior interosseous nerve syndrome and pronator teres syndro...
Carpal tunnel syndrome results from compression of the median nerve within the carpal tunnel. Its causes are numerous and varied.
A useful mnemonic to remember the causes is:
D: diabetes mellitus
Carpenter syndrome, also called acrocephalopolysyndactyly type II (ACPS type II) is an extremely rare autosomal recessive congenital disorder.
It is characterized by a number of features which include:
Carpet lesion is a term for focal a chondral delamination, where articular cartilage is peeled off the subchondral bone plate as a result of shearing forces. It is a frequent finding on hip arthroscopy and is associated with femoroacetabular impingement 1,2.
The carpet lesion was g...
The carpometacarpal (CMC) joints are synovial joints formed by articulations of the distal carpal row and the metacarpal bones.
The carpometacarpal joints are made up of a number of bony articulations 1.
first carpometacarpal: distinct synovial curved saddle joint...
Carpometacarpal (CMC) joint dislocations are uncommon dislocations of the hand.
There is a strong younger male predominance. These injuries account for less than 1% of hand injuries 4 and are more common in the dominant hand.
Carrying angle is a small degree of cubitus valgus, formed between the axis of a radially deviated forearm and the axis of the humerus. It helps the arms to swing without hitting the hips while walking. In full flexion these axes become aligned.
Normally it is 14° (female) and 11° (male) away ...
The term cartilage injury summarizes a spectrum of different cartilage lesions which is usually used in the context of hyaline cartilage damage within diarthrodial joints.
In a narrower sense, the term cartilage injury describes types of articular injury with sparing of bone and the subchondral...
Cartilage interface sign, also referred to as double cortex sign, refers to the sonographic presence of a thin markedly hyperechoic line at the interface between the normally hypoechoic hyaline articular cartilage of the humeral head and an abnormally hypoechoic supraspinatus tendon. This arises...
Cartilage repair and reconstruction comprises different surgical methods for the restoration of the chondral surface within different diarthrodial joints, with the goal to promote cartilage healing, to alleviate patient symptoms as well as to enable them to return to daily activities and sports ...
Cartilaginous joints are a type of joint where the bones are entirely joined by cartilage, either hyaline cartilage or fibrocartilage. These joints generally allow more movement than fibrous joints but less movement than synovial joints.
Primary cartilaginous joint
These cartilaginous joints...
The differential for cartilaginous lesions includes:
The cases featured in these video lectures are specifically selected to teach important concepts in radiology over a broad range of topics. The tutorials vary in difficulty from basic to advanced. For maximum learning, try the cases for yourself in Radiopaedia quiz mode first.
We love this ser...
The Castellvi classification is used for lumbosacral transitional vertebra (LSTV):
type I: enlarged and dysplastic transverse process (at least 19 mm)
type II: pseudoarticulation of the transverse process and sacrum with incomplete lumbarization/sacralization; en...
Catel-Manzke syndrome is a digitopalatal syndrome initially described in 1961. Inheritance pattern is unknown. Radiographic findings include micronagthia and accessory ossicles at the bases of the metacarpals.
The Caton-Deschamps index is used to measure patellar height and identify patella alta and patella baja. The Caton-Deschamps index relies upon the length of the patellar articular surface and its distance from the tibia, reducing erroneous measurements in those with long patella bodies, as measu...
Cat-scratch disease, a manifestation of bartonellosis, is a zoonotic bacterial infection caused by the Bartonella henselae microorganism. It is typically elicited by a scratch of a cat.
The disease has a varying clinical picture ranging between localized lymphadenitis an...
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 ...
Cellular angiofibromas are benign densely vascularized fibroblastic neoplasms usually found in the lower genital tract specifically vulva, vagina or perineum in women and the scrotum or groin in men.
Cellular angiofibromas are rare tumors found in the adult population. There is no...
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.
peripheral vascular d...
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 the narrowing of the spinal canal, nerve root canals, or intervertebral foramina of the cervical spine.
normal AP diameter is ...
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...