The crescent sign refers to a linear cleft due to subchondral fracture in the setting of osteonecrosis.
It was originally described as a radiographic finding, however, it can also be seen on cross-sectional imaging.
In the setting of Legg-Calve-Perthes disease, it heralds the beginning of the ...
CREST syndrome (also known as limited systemic sclerosis or limited scleroderma) is a variant of progressive systemic sclerosis (PSS) and stands for
C - calcinosis
R - Raynaud phenomenon
E - oesophageal dysmotility
S - sclerodactyly
T - telangiectasia
The crista galli is a thick, midline, smooth triangular process arising from the superior surface of the ethmoid bone, projecting into the anterior cranial fossa. It separates the olfactory bulbs, which lie either side of it in the olfactory fossae of the cribriform plate. It serves as an anteri...
Critical shoulder angle (CSA) is a parameter that in some studies 1 correlates with rotator cuff tears (RCT) or glenohumeral osteoarthritis (OA). Some studies 5,6 have shown CSA not associated with RCT.
The CSA measures acromial cover and the inclination of the glenoid, integrating both anatom...
The critical zone of the rotator cuff is an area approximately 8-15 mm from the insertion of the rotator cuff tendons onto the greater tubercle of the humeral head, mainly within the supraspinatus tendon. This is a watershed zone between the anterior and posterior circumflex humeral, thoracoacro...
A critical zone tear is referred to as a rotator cuff tear in the critical zone of the rotator cuff, described approximately 8-20 mm proximal of the insertion site.
Common in adults and older people not so common in children and adolescents 2.
The clinical ...
The crossing sign is seen on true lateral plain radiographs of the knee when the line of the trochlear groove crosses the anterior border of one of the condyle trochlea. It is a predictor of trochlear dysplasia. Trochlear dysplasia has been linked to recurrent patellar dislocation 1,2,4. The cro...
The crossover sign, also known as the 'figure of 8' sign, is a plain film sign that indicates acetabular retroversion 2. Acetabular retroversion is a form of pincer morphology and predisposing factor for femoroacetabular impingement and is thought to promote osteoarthritis of the hip 3.
Cross over toe deformity is a type of deformity where one toe may deviate medially or laterally crossing another toe.
It has been reported to be more commonly seen in women over the age of 50 years 1, and in patients with hallux valgus.
It can occur if there is a unil...
Crouzon syndrome is rare disorder characterized by premature craniosynostoses.
abnormal calvarial shape: in severe case can give a "cloverleaf skull"
shallow orbits with exophthalmos
mid facial hypoplasia
It carries an autosomal dominant...
Crowned dens syndrome is an inflammatory condition resulting from crystal deposition in the cruciform and alar ligaments surrounding the dens, appearing as a radiopaque 'crown' surrounding the top of the dens. It typically presents with pain and increased inflammatory markers.
The location of the cruciate ligament insertions onto the femur can be remembered with the mnemonic:
AE: anterior onto external condyle
PI: posterior onto internal condyle
The cruciate ligament of the atlas (also known as the cruciform ligament) is an important ligamentous complex that holds the posterior dens of C2 in articulation at the median atlantoaxial joint. It lies behind a large synovial bursa (surrounded by loose fibrous capsule) and consists of two band...
Crystal arthropathies are a group of joint disorders due to deposition of crystals in and around joints which lead to joint destruction and soft tissue masses.
The most common arthropathies are:
gouty arthropathy due to monosodium urate (MSU) deposition
pseudogout due to calcium py...
The C sign is an important radiological sign which may be seen on a lateral radiograph of the ankle in those with the talocalcaneal subtype of tarsal coalition. It can be seen in both osseous and nonosseous coalition.
A continuous C-shaped arc on a lateral ankle radiogr...
CT guided bone biopsy is a type of image guided biopsy.
It may be performed using the 'CT fluoroscopy' capabilities of modern CT scanners or with the traditional step-wise approach.
CT biopsies are usually performed using a co-axial needle technique to gain a stable position through which the ...
The cubital fossa (a.k.a. antecubital fossa) (plural: fossae) is an inverted triangular space that forms the transition between the arm and the forearm. It is located anterior to the elbow joint.
The terms cubital/antecubital fossa are also used in surface anatomy for the skin overlying this re...
The cubital tunnel is a space through which the ulnar nerve passes posterior to the medial epicondyle of the humerus.
cubital tunnel retinaculum (also known as ligament or band of Osborne), extends from the olecranon to the medial epicondyle
Cubital tunnel syndrome is a type of ulnar nerve compression neuropathy (tunnel syndrome) due to pathological compression of the ulnar nerve along its course within the cubital tunnel.
The compression of the ulnar nerve at the elbow is the second most common peripheral neuropathy ...
Cubitus varus (gunstock deformity) is a malalignment of the distal humerus that results in a change of carrying angle from the physiologic valgus alignment (5-15 degrees) of the arm and forearm to varus malalignment. Historically, it is a complication of supracondylar fractures with a frequency ...
The cuboid bone is one of the tarsal bones located lateral to the lateral cuneiform bone and has an important articulation with the calcaneus.
location: lies laterally in the midfoot
articulations: proximally with the calcaneus, medially with the lateral cuneiform and navicular, and d...
Cuboid syndrome is a cause of lateral midoot pain, believed to result from abnormal articulation of the cuboid with the calcaneus (calcaneocuboid joint).
Cuboid syndrome presents with lateral foot pain and swelling, often diffuse and similar to an ankle (ligament) sprain ...
There are three cuneiform bones in the tarsus of a normal human foot, they are from medial to lateral:
History and etymology
Cuneiform means wedge-shaped from the Latin words 'cuneus' meaning wedge and 'form' referring to shape.
Currarino-Silverman syndrome, also known as pectus carinatum type 2 deformity, is a rare disorder.
Patients present with a high carinate chest deformity due to a premature fusion of the manubriosternal joint and sternal ossification centers. Congenital heart diseases have...
The curtain sign, also known as the draped curtain sign, in neuroimaging refers to the appearance of a vertebral body mass that extends posteriorly towards the anterior epidural space.
The posterior longitudinal ligament is strongly attached to the posterior vertebral body cortex in the midline...
Cutaneous and subcutaneous metastases are not uncommon, occurring in ~5% (range 0.7-10.4%) of internal malignancies, and representing 2% of skin cancers. The Sister Mary Joseph nodule is a well known cutaneous metastasis.
These metastases can come from hematogenous or lymphatic sprea...
Cutis laxa is a rare dermatological condition, characterized by elastic fiber loss, resulting in very lax skin. Patients can also develop emphysema.
Cutis laxa may be inherited (autosomal dominant, autosomal recessive, or X-linked recessive) or may occur sporadically.
A cyamella is a rare sesamoid bone that exists as a normal variant within the popliteus tendon, characteristically located at the lateral aspect of the distal femur in the popliteal groove.
Cyamella is best seen on the AP view of plain radiograph as opposed to fabella, which is best appreciated...
The cyclops lesion, also known as localized anterior arthrofibrosis, is a painful anterior knee mass that arises as a complication of anterior cruciate ligament (ACL) reconstruction, although has rarely been reported in patients with ACL injuries that have not been reconstructed.
The cyma line is a radiological sign of the smooth joining of the midtarsal joint lines as a "lazy S-shape" of the talonavicular and calcaneocuboid joints on both AP and lateral views.
Disruption of the cyma line with anterior shift of the talonavicular joint can indicate tru...
Cyriax syndrome, also known as slipping rib syndrome, occurs when hypermobility of the rib cartilage of the lower ribs slips and moves, leading to pain in lower chest or upper abdomen 1.
This condition may occur at any age, but is reportedly more common in middle-aged adults, and ...
Cysticercosis is a parasitic tissue infection caused by ingestion of tapeworm eggs through a fecal-oral transmission or auto-infection. Humans act as a definitive host in this disease.
CNS manifestations are discussed individually on neurocysticercosis.
The disease is endemic in ...
The musculoskeletal manifestations of cystic fibrosis are uncommon compared to the well known respiratory manifestations.
For general discussion of cystic fibrosis, and a discussion of its other manifestations, please refer to:
cystic fibrosis (parent article)
pulmonary manifestations of cys...
Cystic synovial hyperplasia is a form of synovial hyperplasia which has several cystic components.
May be seen as a multi-cystic synovial proliferative lesion.
T1 C+: less intense peripheral enhancement only.
on MR imaging it can mimic a syn...
There is broad differential for cyst-like lesions around the knee.
popliteal synovial cyst - Baker cyst
intra-articular ganglion cyst
ACL ganglion cyst
PCL ganglion cyst
Hoffa fat pad ganglion cyst
extra-articular ganglion cyst
The dagger sign is a radiographic feature seen in ankylosing spondylitis as a single central radiodense line on frontal radiographs related to ossification of the supraspinous and interspinous ligaments secondary to enthesitis.
The Dameron-Lawrence-Botte classification, or Lawrence-Botte classification, is a commonly used nomenclature for proximal fifth metatarsal fractures, which are categorized into one of three anatomic zones of involvement:
zone 1: tuberosity (styloid process) avulsion fracture
Danon disease is an X-linked dominant cause of debilitating cardioskeletal myopathy and is a lysosomal storage disorder.
Although considered rare, the exact incidence is unknown 1.
Danon disease is characterized by the triad of 1-4:
The de Carvalho index is used to measure patellar height and identify patella alta. Similar to the Caton-Deschamps index, it 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 measured in...
Decompression sickness (DCS), also known as diver's disease, aerobullosis, the bends or caisson disease, is an uncommon diving-related decompression illness that is an acute neurological emergency typically occurring in deep sea divers.
Decompression sickness can be furt...
A dedifferentiated chondrosarcoma is a combined tumor made up to two components which are often sharply demarcated from one another (thus raising the possibility of it representing a collision tumor).
conventional chondrosarcoma (low grade)
dedifferentiated high grade areas
malignant fibrous ...
Dedifferentiated liposarcomas (DDLPS) are malignant adipocytic soft tissue neoplasms that have progressed from primary or recurrent atypical lipomatous tumors/well-differentiated liposarcomas and are characterized by a much higher rate of recurrence, metastasis in about ¼ of the cases and a much...
Deep bursae are those bursae that are located deep to the fibrous fascia and are normally located between muscles or muscle and bone. These bursae form in utero alongside synovial joint formation 1.
In contrast, superfical bursae are located superficial to the fibrous fascia.
Deep fibrous histiocytomas are histologically benign fibrohistiocytic tumors usually found in the subcutaneous or deep soft tissues which are able to metastasize.
Deep fibrous histiocytomas are rare tumors. They make up for less than 1% of all fibrohistiocytic tumors and occur ove...
The deep infrapatellar bursa is one of many bursae surrounding the knee joint and shares the name with its superficial, subcutaneous counterpart.
It is located above the tibial tubercle immediately superior to the distal patellar tendon insertion and posterior of the lower third ...
Deep infrapatellar bursitis refers to an inflammation of the deep infrapatellar bursa and is an uncommon condition in children.
Sports and activities involving a great amount of running and jumping are considered risk factors for developing deep infrapatellar bursiti...
The deep peroneal (fibular) nerve is one of two terminal branches of the common peroneal nerve.
origin: the terminal branch of common peroneal nerve in the lateral compartment of the leg
course: passes into the anterior compartment of the leg, where it courses inferiorly into the dors...
The deep posterior compartment of the leg is one of the four compartments in the leg between the knee and foot. Muscles within this compartment primarily produce ankle plantarflexion and toe flexion, with exception of the popliteus which acts on the knee. Of the two posterior compartments, the d...
The deep posterior tibiotalar ligament (DPTTL) is one of the two deep components and the strongest part of the deltoid ligament 1,2.
The deep posterior tibiotalar ligament is covered by the superficial posterior tibiotalar and tibiocalcaneal ligaments. It is a broad and thick lig...
The deep sulcus sign can refer to two different radiographic signs but is best known in the chest:
deep sulcus sign (chest): of pneumothorax on supine CXR:
deep sulcus sign (knee): better known as the lateral femoral notch sign of ACL injury
Degenerative disc disease (DDD) is an exceedingly common entity in the spine, encountered with increasing frequency throughout life and becoming almost universal in late adulthood to a varying degree. It is related to a combination of biomechanical stresses and genetic predisposition which alter...
Degloving injuries can refer to a number of conditions:
degloving soft tissue injury
Morel-Lavallée lesion (closed degloving soft tissue injury)
intramuscular degloving injury
degloving bowel injury
Degloving soft tissue injuries can be extensive and quite severe conditions. These may be open or, less commonly, closed injuries, which are known as Morel-Lavallée lesions. This article focuses on open injuries, with closed injuries discussed in the Morel-Lavallée article.
Dehiscence is a general term referring to 'splitting open' and is used in a variety of contexts in medicine generally and radiology more specifically.
The two most common usages are:
splitting open of a wound (e.g. sternal dehiscence)
loss of bone separating one structure from another (e.g. ...
A generalized retardation in skeletal maturation has different causative or etiological factors, these can be classified as follows:
chronic ill health
congenital heart disease (especially cyanotic)
chronic renal disease
inflammatory bowel disease
malnutrition: failure to thrive (FTT)
Delayed onset muscle soreness (DOMS) refers to the muscular pain and swelling that follows unaccustomed exertion.
Patients may have an ache in affected muscles with reduced strength 4.
DOMS is thought to occur from reversible microstructural muscle injury that...
The Delbet classification helps predict the risk of avascular necrosis of the femoral head in neck of femur fractures, as well as determine operative vs non-operative management.
type I: trans-epiphyseal separation
fracture through proximal femoral physis, and represents Salte...
The delta sign has been described in several different pathologies:
delta sign (brain)
empty delta sign (brain)
double delta sign (MSK)
Deltoid ligament injuries involve the deltoid ligament that forms the medial part of the ankle joint. It attaches the medial malleolus to multiple tarsal bones.
Mechanism of injury
It occurs due to eversion and/or pronation injury, or can be associated with lateral ankle fractures.
The complex of the medial collateral ligaments of the ankle joint is collectively called deltoid ligament. It attaches the medial malleolus to multiple tarsal bones.
The ligament is composed of two layers. The superficial layer has variable attachments and crosses two joints whil...
The deltoid muscle (also known as deltoideus muscle) is the largest of the shoulder muscles. The muscle is composed of three heads (clavicular, acromial and spinous), although electromyography suggests that there are at least seven control regions that could act independently 1.
The deltopectoral groove is located between the superolateral aspect of the pectoral region and the deltoid muscle. It runs obliquely from superomedial to inferolateral and contains the cephalic vein which at the upper margin of the groove dives deep to pierce the clavipectoral fascia and enter ...
Denervation changes in muscles or denervation myopathy can be observed in a number of settings and results from partial or complete loss of innervation.
There is a wide spectrum of clinical manifestations:
temporary or permanent
symptomatic or asymptomatic.
Causes include 2:
The differential diagnosis for a dense base of the skull includes:
Van Buchem disease
The differential diagnosis of dense metaphyseal bands is wide.
chronic anemia, e.g. sickle cell disease, thalassemia
chemotherapy, e.g. methotrexate
growth acceleration lines following growth arrest due to systemic illness or stress in infancy or childhood, e.g...
Common causes of dense transverse metaphyseal lines can be remembered using the mnemonics:
D: D-vitamin intoxication
E: elemental arsenic and heavy metals (lead, bismuth, phosphorus)
N: normal variation
S: systemic illness
E: estrogen to mother ...
Densitometric vertebral fracture assessment (VFA) is an image of the lumbar and thoracic spine acquired on dual energy x-ray absorptiometry (DXA) scanners, for the purpose of diagnosing osteoporotic vertebral fractures.
The technique is available on DXA scanners under a variety of...
Depositional arthropathy refers to a group of joint disorders caused by the depositional of substances within and/or around joints.
calcium pyrophosphate dihydrate deposition disease (CPPD)
hydroxyapatite crystal deposition disease (HADD)
Depressed skull fractures result in the bone of the skull vault being folded (depressed) inward into the cerebral parenchyma. It is usually the result of a high energy impact to the skull.
These mostly (~75%) occur in the frontoparietal region 3.
There are a number of ...
De Quervain tenosynovitis, also known as washerwoman's sprain/strain, is a painful stenosing tenosynovitis involving the first extensor (dorsal) tendon compartment of the wrist (typically at the radial styloid). This compartment contains the abductor pollicis longus (APL) and extensor pollicis b...
Dercum disease, also known as adiposis dolorosa, is a rare disorder of subcutaneous tissue characterized by multiple painful lipomas.
Although the exact incidence is unclear, Dercum disease affects women more than men 1,2. It is usually sporadic, however, autosomal dominant forms ...
Dermal nerve sheath myxomas are benign peripheral nerve sheath tumors usually originating from the skin or subcutaneous tissues.
The previous term was ‘classic or myxoid variant of neurothekeoma’ but recent data has shown that they are biologically and clinically distinct from neur...
Dermatofibrosarcoma protuberans (DFSP) is a low-grade malignant tumor arising from dermal and subcutaneous tissues and is the most common cutaneous sarcoma (although overall still quite rare). It is most commonly found at the trunk and proximal extremities 6.
Its behavior is notable for a high ...
Dermatographia, also known as skin writing, refers to a skin condition in which skin scratches causes linear red marks. The cause is unknown; however, it is related to penicillin use and mastocytosis.
Dermatomyositis is an autoimmune inflammatory myositis, which like its closely-related condition polymyositis, carries an increased risk of malignancy.
There is a recognized female predilection. It has a bimodal age of presentation depending on the variant:
A derotational screw is an orthopedic device used for internal fixation of fractures to, unsurprisingly, limit rotation of the fracture.
They are applied across fractures at risk of rotation and hence avascular necrosis.
Describing a bone lesion is an essential skill for the radiologist, used to form an accurate differential diagnosis for neoplastic entities, and occasionally non-neoplastic. In addition to patient demographics, the radiographic features of a bone lesion are often the primary determinant of non-h...
Describing a fracture is a basic requirement when making an assessment of a plain radiograph. There are many ways to approach the assessment of the radiograph; this is just one approach.
I: Describe the radiograph
What radiograph (or radiographs) are you looking at? Check the who, what, why, w...
Desmin is a muscle-specific protein. It is the main intermediate filament protein and a key component in the cytoskeletal network of muscle cells e.g. in the myocardium, where it is ampler than in the skeletal or smooth muscles. It interacts with other proteins to support the myofibrils at the l...
Desmoid tumors are benign, non-inflammatory fibroblastic tumors with a tendency for local invasion and recurrence but without metastasis.
The terms desmoid tumor and aggressive fibromatosis are occasionally used synonymously by some authors 9. This article will focus on the abdomin...
Desmoplastic fibroblastoma are rare benign fibroblastic soft tissue tumors with an abundant collagenous or myxocollagenous stroma seen in adults.
Desmoplastic fibroblastoma is also known as collagenous fibroma 1-3.
Desmoplastic fibroblastomas are rare and usually oc...
Desmoplastic fibromas are extremely rare bone tumors that do not metastasize but may be locally aggressive. They are considered to be a bony counterpart of soft tissue desmoid tumors and are histologically identical.
Desmoplastic fibroma of bone is rare and mostly found in young ...
Developmental dysplasia of the hip (DDH), or in older texts congenital dislocation of the hip (CDH), denotes aberrant development of the hip joint and results from an abnormal relationship of the femoral head to the acetabulum.
Unlike CDH, developmental dysplasia of the hip is not confined to c...
dGEMRIC, or delayed gadolinium-enhanced MRI of cartilage is a technique that can be used quantitatively to assess glycosaminoglycan content of cartilage or qualitatively to asses the overall structures of cartilage. When the technique is adapted and applied to menisci it is called dGEMRIM.
Diabetic myonecrosis is an uncommon complication of diabetes mellitus, occurring in patients with chronic poor glycemic control.
There is a slight predilection for females and patients with type 1 diabetes. The average age of presentation is 40 years.
Diaphragmatic eventration refers to an abnormal contour of the diaphragmatic dome with no disruption to the diaphragmatic continuity. It typically affects only a segment of the hemidiaphragm, compared to paralysis/weakness where the entire hemidiaphragm is typically affected.
Diaphragmatic paralysis (also considered very similar to the term diaphragmatic palsy) can be unilateral or bilateral.
Clinical features are highly variable according to underlying etiological factor:
unilateral paralysis: asymptomatic in most of the patients as the othe...
Diaphyseal lesions are found centered in the diaphysis, the central tubular segment of long bones.
simple bone cyst
myeloma / plasmacytoma
round cell tumor, e.g. Ewing sarcoma (child...
A mnemonic for a short list of diaphyseal lesions is:
C: bone cysts
E: enchondroma/Ewing sarcoma
M: bone metastasis
E: eosinophilic granuloma
N: non-ossifying fibroma (NOF)
The diaphyses (singular: diaphysis), sometimes colloquially called the shafts, are the main portions of a long bone (a bone that is longer than it is wide) and provide most of their length.
The diaphysis has a tubular composition with a hard outer section of hard cortical bone and a central po...
Diarthroses are a functional class of joint that are freely mobile. All synovial joints are considered diathroses.
Diastasis recti (rectus diastasis) or divarication of the recti is a stretching of the linea alba with abnormal widening of the gap between the two medial sides of the rectus abdominis muscle (increased inter-recti distance).
The degree of widening needed for the diagnosis is controversial, wit...
Diastrophic dysplasia (DTD) is a type of short limb skeletal dysplasia (micromelic dwarfism). Adult patients have a stature between 100 and 140 cm.
There may be a relatively increased prevalence in Finland ref.
Typically there is limb shortening, hitchhiker thu...