The double Oreo cookie sign refers to the presence of two hyperintense lines in the superior glenoid labrum, one of which represents a superior labral tear and the other a physiological sublabral recess 1, 2.
This pattern is likened to an Oreo cookie with two layers of (white) cream and three l...
The double PCL sign appears on sagittal MRI images of the knee when a bucket-handle meniscal tear (medial meniscus in 80% of cases) flips towards the centre of the joint so that it comes to lie anteroinferior to the posterior cruciate ligament (PCL) mimicking a second smaller PCL.
A double PCL ...
The doughnut sign refers to the bone scan pattern whereby there is increased uptake peripherally with a photopenic centre. This appearance may be seen in a number of cystic lesions including:
aneurysmal bone cyst
giant cell tumour
simple bone cyst
The doughnut sign is a non-specific sign, an...
Dracunculiasis (also known as guinea worm disease) is a potentially disabling infection caused by Dracunculus medinensis (meaning "little worm from Medina").
The radiologic finding of a calcified guinea worm is common in endemic areas.
In the vast majority of cases (one...
Dripping candle wax sign, also known as flowing candle wax appearance, describes the appearance of sclerotic cortical thickening in melorheostosis. The irregular cortical hyperostosis typically occurs on one side of the involved bone and undulates along much like melted wax down a candle.
Dual-energy x-ray absorptiometry (DEXA) is a technique used to aid in the diagnosis of osteopenia and osteoporosis.
Values are calculated for the lumbar vertebrae and femur preferentially, and if one of those sites is not suitable (e.g. artifact, patient mobility, histor...
Duchenne muscular dystrophy (DMD) is a dystrophinopathy and the most common muscular dystrophy.
DMD has an incidence of 1 in 3500 to 5000 males 1,2. The condition is extremely rare in females due to its inheritance pattern, as discussed below 1.
The dumbbell appearance of spinal tumours refers to a tumour which has both a component within the canal and a component in the paravertebral space contiguous with each other via a thinner tumour component traversing the neural exit foramen.
The appearance can be seen in:
spinal nerve sheath t...
A Dupuytren contracture, or palmar fibromatosis, is a fibrosing condition that characteristically presents as a firm nodularity on the palmar surface of the hand with coalescing cords of soft tissue on the webs and digits.
It is considered the most common of the superficial fibrom...
Duverney fractures are a type of pelvic fracture most commonly occurring in the setting of a direct blow to the ilium, with a resultant isolated iliac wing fracture. It is regarded as a stable injury but may be operated on in the event of severe comminution.
History and etymology
It is named ...
Dynamic hip screws (DHS) are a femoral head-sparing orthopaedic device used to treat femoral neck fractures. It is sometimes referred to as a pin and plate.
Neck fractures that are undisplaced and hence have a low risk of avascular necrosis (Garden I and II fractures) can be treated with head-p...
Dysplasia epiphysealis hemimelica (DEH), also known as Trevor disease, is an extremely rare, non-hereditary disease that is characterised by osteochondromas arising from the epiphyses.
The incidence is estimated at ~1:1,000,000 3. There is a recognised male predilection (M:F = 3:1...
Dystrophic soft tissue calcification is a broad term that encompasses a wide range of pathologies that cause soft-tissue calcification and is caused by calcification of damaged tissues. The amorphous calcification that results may be small or large. In some cases, ossification may occur - this...
This classification was proposed by Eaton and Malerich in 1980, and presently (time of writing, August 2016) along with Keifhaber-Stern classification, is the most widely accepted classification of volar plate avulsion injuries 1.
Knowledge of the orthopaedic Eaton classification is practical ...
Ectodermal dysplasia (ED) refers to a heterogeneous group of genetic disorders that cause abnormal ectoderm development. The effect is a non-progressive defect in the development of two or more tissues derived from embryonic ectoderm.
ED is rare with an estimated prevalence of 1:...
Ectrodactyly (also known as a split hand-split foot malformation, cleft hand or lobster claw hand) is a skeletal anomaly predominantly affecting the hands (although the feet can also be affected). The condition has a highly variable severity.
The estimated incidence is at ~ 1 in 9...
The wrist series is comprised of a posteroanterior, oblique, and lateral projection. The series examines the carpal bones (namely, the scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate and hamate). It also examines the radiocarpal joint along with the distal radius and ulna....
Ehlers-Danlos syndrome comprises a heterogeneous group of collagen disorders (hereditary connective tissue disease).
There is a recognised male predominance.
Clinically manifests by skin hyperelasticity and fragility, joint hypermobility and blood vessel fr...
Elastofibroma dorsi is a benign soft-tissue tumour with a characteristic location and imaging appearance.
It is more frequently seen in older women, with a reported female predilection of 5-13:1. The estimated mean age at diagnosis around 65-70 years.
The elbow is a complex synovial joint formed by the articulations of the humerus, the radius and the ulna.
The elbow joint is made up of three articulations 2,3:
radiohumeral: capitellum of the humerus with the radial head
ulnohumeral: trochlea of the humerus wi...
The elbow AP view is part of the two view elbow series, examining the distal humerus, proximal radius and ulna.
The projection demonstrates the elbow joint in its natural anatomical position allowing for adequate radiographic examination of the articulations of the elbow including the radiohum...
Elbow arthroplasties are an increasingly common joint replacement, most often used for treatment of late stage rheumatoid arthritis, but which may also be used as a treatment for late stage osteoarthritis or complex fractures of the proximal radius, proximal ulna, or distal humerus.
The elbow bursae are a collection of synovial-lined bursae that exist around the elbow. They can be divided into bursae around the olecranon and in the cubital fossa.
Superficial Olecranon Bursa: Lies between the olecranon and the subcutaneous tissue.
Subtendinous Olecranon ...
Elbow dislocation is the second most common large joint dislocation in the adult population.
A dislocation with no fracture is simple whereas an accompanying fracture makes the dislocation complex. The most common fracture is a radial head fracture, although coronoid process fracture is also c...
The elbow extension test is a clinical decision rule aimed at reducing the number of unnecessary elbow radiographs in patients aged ≥3 years.
The test has a specific examination whereby the seated patient, with the arm in supination and 90º shoulder flexion, is asked to fully extend the elbow ...
An elbow joint effusion is a key finding to recognise on an elbow radiograph and should be used as a trigger to search for a fracture.
Finding an effusion
Recognising an elbow joint effusion on lateral radiographs is an essential radiology skill. While the fluid itself is not discretely seen...
The lateral elbow view is part of the two view elbow series, examining the distal humerus, proximal radius and ulna. It is deceptively one of the more technically demanding projections in radiography 1-3.
The projection is the orthogonal view of the AP elbow allowing for examination of the ulna...
Elbow ossification occurs at the six elbow ossification centers in a reproducible order. Being familiar with the order of ossification of the elbow is important in not mistaking an epicodylar fracture for a normal ossification center.
The order of appearances of the elbow os...
Mnemonics for elbow ossification include CRITOE and CRITOL. These are essentially the same, apart from the terminal letter which represents the External or Lateral epicondyle.
C - capitellum
R - radial head
I - internal epicondyle
T - trochlea
O - olecranon
E - external ...
Elbow radiographs are common plain films that are obtained frequently in the emergency department.
anterior humeral line
drawn down the anterior surface of the humerus
should intersect the middle 1/3 of the capitellum
if it does not, think distal humeral fracture...
The elbow series is a set of radiographs taken to investigate elbow joint pathology, often in the context of trauma. It usually comprises an AP and lateral projection, although other non-standard, modified projections are utilised for specific indications.
Elbow x-rays are indicate...
An elbow series is the standard series of radiographs that are performed when looking for evidence of fracture, dislocation or elbow joint effusion following trauma.
This is a summary article. For more information, you can read a more in-depth reference article: elbow series....
Elbow synovial fold syndrome refers to a condition where patients experience a cluster of symptoms due to the presence of synovial folds (also known as synovial fringe or plicae).
It tends to be more common in athletic young adults. It is associated with certain sporting activitie...
Elephantiasis nostras verrucosa is a rare cause of chronic lymphoedema, arising in the setting of chronic nonfilarial lymphedema caused by bacterial or noninfectious obstruction of the lymphatics.
It presents mostly as grossly oedematous and disfigured lower extremities, ...
The atypical 11th rib is one of two floating ribs.
The 11th rib has a single facet on its head for articulation with the T11 vertebra. It has a short neck and no tubercle. The angle is slight. Its costal groove is shallow. The internal surface of this rib faces slightl...
The embryonal subtype of rhabdomyosarcoma is the most common variety of rhabdomyosarcoma, accounting for 50-70% of cases 1-2. It is typically seen in children below the age of 15.
Embryonal rhabdomyosarcomas are further divided into three sub types 1:
spindle cell rhabdomyosarcoma
Emphysematous osteomyelitis is an extremly rare form of osteomyelitis which is complicated by infection with gas forming organims. Only a handful of cases are published in literature.
Commonely reported organisms include 1
Empyemas are purulent inflammatory collections within a body cavity. They are similar to abscesses, which arise within parenchymal tissue rather than occupying a pre-existing anatomical space.
Colloquially, the term empyema is used to refer to thoracic empyemas but there are variou...
Enchondromas (or chondromas 7) are a relatively common benign medullary cartilaginous neoplasm with benign imaging features. They account for the E in the popular mnemonic for bubbly bone lesions FEGNOMASHIC. They are sometimes classified under the umbrella term low grade chondral series tumours...
Enchondromatosis, also known as Ollier disease, is a non-hereditary, sporadic, skeletal disorder characterised by multiple enchondromas that are principally located in the metaphyseal regions.
Some authors make a distinction between Ollier disease and enchondromatosis on the basis ...
Distinguishing between enchondromas and low-grade conventional chondrosarcomas is a frequent difficulty as the lesions are both histologically and radiographically very similar.
It is important to remember, though, that differentiating between them may be a moot point since both can either be c...
Endochondral ossification describes the process of ossification from mesenchymal cells (stem cells) with a cartilaginous template and is involved in the healing process of fractures.
Bone formation occurs at centers of ossification (or ossification centres) which are either primary or secondary...
Endosteal scalloping refers to the focal resorption of the inner layer of the cortex (i.e. the endosteum) of bones, most typically long bones, due to slow-growing medullary lesions.
It is important to note that although it is evidence of a slow non-infiltrative lesion, it does not equate to ben...
Enlocated is a term popular among Australasian (Australia and New Zealand) radiologists and orthopaedic surgeons to describe a joint that is not dislocated.
It does not appear in the Oxford dictionary, nor is it widely used elsewhere in English-speaking countries. Most authors prefer the terms...
The Enneking surgical staging system (also known as the MSTS system) is based on tumour grade, local spread and metastatic disease of malignant musculoskeletal tumours.
It does not classify skull tumours or marrow-originating tumours (e.g. lymphoma, plasmacytoma / multiple myeloma, Ewing sarcom...
An enostosis (pl. enostoses, also known as a "bone island") is a common benign bone lesion, usually seen as an incidental finding. They constitute a small focus of compact bone within cancellous bone. Enostoses can be seen on radiographs, CT, and MRI, and are considered one of the skeletal “don’...
Enteropathic arthritis (EA) is a form of chronic, inflammatory arthritis associated with the occurrence of an inflammatory bowel disease (IBD), and is classified as a form of seronegative spondyloarthropathy.
Approximately 20% of people with Crohn disease or ulcerative colitis may...
An enthesis (pl. entheses) is the connective tissue junction where ligaments and tendons attach to bone.
There are two types of entheses:
The ligament or tendon attaches directly to the bone.
Enthesitis refers to inflammation of the enthesis (the attachment of ligament or tendon to bone).
Enthesitis may be the result of repetitive mechanical stress or a more generalised inflammatory condition. Enthesitis is associated with the HLA-B27 inflammatory arthritides such as ankylosing spo...
Enthesopathy is a broad term that includes any disorder that occurs where tendons or ligaments attach to bone (the enthesis).
The causes of enthesopathy is broad. It may be localised and secondary to repetitive mechanical strain, or secondary to another condition which may be confined to a sing...
Eosinophilic fasciitis (EF), also known as Shulman syndrome, is an uncommon connective tissue disorder.
It can potentially present at age. There is a recognized female predilection 3,4.
Patients typically present with pronounced extremity oedema and skin in...
Epibasal fractures of the thumb (also called pseudo-Bennett fracture) are two-piece fractures of the proximal first metacarpal bone. They are usually stable, depending on the degree of displacement, and often do not require surgery. It is important to distinguish them from intra-articular fractu...
Epicondyle fractures are common injuries in children. They represent 10% of all elbow fractures in children and usually occur in boys after a fall on an outstretched arm.
Medial epicondyle fractures comprise most of these injuries. They can usually be treated with splinting and early physiother...
Epidermal inclusion cysts are common cutaneous lesions that represent proliferation of squamous epithelium within a confined space in the dermis or subdermis.
Synonyms include "epidermoid cyst" and "epidermoid inclusion cyst". These are occasionally termed "sebaceous cyst", althoug...
Epidermolysis bullosa refers to a rare group of genetically determined conditions characterised by blistering of the skin. This can be limited to the soles and palms or extensive whole body involvement.
limited to the mucosa of the gastr...
Epidural blood patch is a treatment option for patients with craniospinal hypotension or post lumbar puncture headaches. The procedure can be done blind or under fluoroscopic or CT guidance, and is performed predominantly by radiologists and anaesthetists.
Epidural lipomatosis refers to an excessive accumulation of fat within the spinal epidural space, typically in the lumbar region, such that the thecal sac is compressed, and in some instances results in compressive symptoms.
Demographic of affected individuals reflects the underl...
An epiphyseal bracket represents an abnormal development of physeal tissue along the diaphysis which occurs in the hand and the feet 1.
An epiphyseal equivalent refers to bones that are considered similar to the epiphyses and therefore have a similar list of diseases that cause pathology.
Epiphyseal lesions comprise of tumours and other pathologies that occur around the epiphysis and any epiphyseal equivalent bone.
Common differential diagnoses include 2-4:
chondroblastoma: rare epiphyseal tumour found in young adults; it does not usually extend into the...
The differential diagnosis of epiphyseal overgrowth includes:
juvenile rheumatoid arthritis
Legg-Perthes disease (healed )
dysplasia epiphysealis hemimelica
fibrous dysplasia of epiphysis
pyogenic arthritis (chronic)
Epiphyseal spur refers to spur seen in skeletally mature individuals arising at the level of closed epiphyseal line. It may be seen in any bone containing epiphysis.
The epiphyses (singular: epiphysis) are the rounded portions at the ends of a bone separated from the metaphysis by the physis. The epiphysis contributes to a joint, compared with an apophysis which is a site of tendon or ligament attachment. Once the growth plate has fused, the epiphysis and me...
Episternal (or suprasternal) ossicles are accessory bones and a normal variant of the sternum. They result from supernumerary ossification centers and are seen in ~4% (range 1-7%) of the population.
Episternal ossicles are usually located posterior or superior to the superior bor...
There are numerous eponymous fractures which are named after the people who first described their existence 1:
Bankart fracture: glenoid
Barton fracture: wrist
Bennett fracture: thumb
Bosworth fracture: ankle
Chance fracture: vertebral
Charcot joint: foot
Chopart fracture: foot
Erdheim-Chester disease (ECD) is a rare non-Langerhans cell, non-familial multisystemic granulomatosis, with widespread manifestations and of highly variable severity. The most common presenting symptom is bone pain.
Erdheim-Chester disease is a rare, non-inherited disease of midd...
The erector spinae group is the intermediate layer of the intrinsic muscles of the back. This group is made of three subgroups, with the group divisions occurring by location. The iliocostalis group occurs most laterally, followed by the longissimus group, and finally the spinalis as the most me...
There are multiple handy mnemonics to recall the erector spinae muscles. They usually describe the position from lateral to medial.
I Like Standing
I Love Sex
I Long for Spinach
I Like Siri
An Erlenmeyer flask deformity refers to a radiographic appearance typically on a femoral radiograph demonstrating relative constriction of the diaphysis and flaring of the metaphysis.
lysosomal storage disease
Gaucher disease - osteopenia with Leg...
Some of the causes of an Erlenmeyer flask deformity can be recalled with the following mnemonics:
C: craniometaphyseal dysplasias
sickle cell disease
N: Niemann-Pick disease
G: Gaucher disease
Differential diagnosis of erosion of the superior aspects of the ribs include:
Erosion of the odontoid peg can result from a number of pathological entities:
rheumatoid arthritis: classic 1-2
systemic lupus erythematosus
calcium pyrophosphate arthropathy (CPPD): relatively common
non-inflammatory arthropathy: osteoar...
Erosive arthritis has a broad differential, including:
clinically an acute inflammatory attacks (swelling, erythema, pain) in postmenopausal woman
typically includes the DIPs, PIPs 1st CMC joint 6, but not the metacarpophalangeal (MCP) joints and large joints
Erosive (inflammatory) osteoarthritis (EOA) is a form of osteoarthritis (OA) where, as the name implies, there is an additional erosive/inflammatory component.
There is marked female predilection (F:M ~12:1), typically presenting in the postmenopausal patient.
Essex-Lopresti fracture-dislocations comprise of a comminuted fracture of the radial head accompanied by dislocation of the distal radioulnar joint (DRUJ). The force of trauma is transmitted down the forearm through the interosseous membrane causing disruption. The DRUJ injury may be missed lead...
Recurrent bone tumours are a common complication post curettage or resection.
Radiographs taken pre- and postoperatively are sufficient for evaluation of recurrence based on the following features:
matrix mineralisation (characterist...
Ewing sarcoma is the second most common highly malignant primary bone tumour of childhood after osteosarcoma, typically arising from medullary cavity with invasion of Haversian system. They usually present as moth-eaten destructive permeative lucent lesions in the shaft of long bones with large ...
Ewing sarcoma family of tumours (ESFT), also referred as Ewing sarcomas of the chest wall, are malignant tumours affecting children and young adults, originating either from the osseous structures or the soft tissues of the chest wall.
On imaging, they are usually characterised as a large extr...
Excessive lateral pressure syndrome (ELPS) is the abnormal lateral tilt of the patella without lateral translation and considered one of the relatively common causes of anterior knee pain.
It can affect both adolescents or adults.
Patients usually present ...
Exostoses are defined as benign growths of bone extending outwards from the surface of a bone. It can occur in any bone and be triggered by a number of factors. There are a number of examples of exostoses that occur due to local irritant stimuli:
exostosis of the external audit...
Expansile lytic bone lesions without cortical destruction can result from various benign and malignant neoplastic pathologies, causes include 1:
unicameral bone cyst
aneurysmal bone cyst (eccentric)
chondromyxoid fibroma (eccentric)
non-ossifying fibroma (eccentric)
Extension tear drop fracture typically occurs due to forced extension of the neck with resulting avulsion of the anteroinferior corner of the vertebral body. Extension teardrop fractures are stable in flexion, and unstable in extension as the anterior longitudinal ligament is disrupted. Extensio...
Extensor carpis radialis brevis (ECRB) is a muscle of superficial layer on posterior compartment of the forearm. It passes through the 2nd extensor compartment of the wrist. ECRB is one of the three muscles forming the mobile wad of Henry.
origin: lateral epicondyle of the humerus, ann...
Extensor carpis radialis longus (ECRL) is a muscle of the superficial layer in the posterior compartment of the forearm. It passes through the 2nd extensor compartment of the wrist. It is one of the three muscles forming the mobile wad of Henry.
origin: lateral supracondyle ridge of hu...
Extensor carpis ulnaris (ECU) is a muscle of the superficial layer of the posterior compartment of the forearm. It is separated from the extensor digitorum and the extensor digiti minimi muscles by a distinct intermuscular septum. It is the only forearm extensor that lies in its own fibro-osseou...
The extensor tendons at the level of the wrist are divided into six extensor compartments that are designated by Roman numerals from lateral to medial 1:
I: extensor pollicis brevis, abductor pollicis longus
II: extensor carpi radialis longus, extensor carpi radialis brevis
III: extensor poll...
Extensor digiti minimi (EDM) is a muscle of the superficial layer of the posterior compartment of the forearm, and with other extensor muscles arises from a common extensor tendon attached to the lateral epicondyle of the humerus. The EDM represents a medial group of superficial extensor muscles...
Extensor digitorum (ED), also known as extensor digitorum communis (EDC), is a muscle of the superficial layer of the posterior compartment of the forearm and with other extensor muscles arises from a common tendon attached to the lateral epicondyle of the humerus. ED represents a medial group o...
The extensor digitorum brevis manus (EDBM) muscle is an accessory muscle in the hand and is a normal anatomical variant.
origin: distal radius and posterior radiocarpal ligament
insertion: extensor hood of 2nd or 3rd digits (variable)
innervation: posterior interosseous nerve
The extensor digitorum brevis muscle is a muscle on the dorsal surface of the foot which helps extend digits 2 through 4.
origin: superolateral surface of calcaneus
insertion: lateral sides of the tendons of extensor digitorum longus of toes II to IV
action: extension of toes II to I...
Extensor digitorium longus (EDL) is a thin muscle situated in the anterior leg lateral to extensor hallucis longus and extends the lateral four toes.
origin: lateral tibial condyle, medial surface of the middle portion of the fibula and superior portion of the anterior surface of the i...
The extensor hallucis brevis is a muscle on the dorsal surface of the foot which helps to extend the big toe.
superolateral surface of calcaneus
base of proximal phalanx of great toe
extension of metatarsophalangeal joint of great toe
Extensor hallucis longus is a thin muscle in the anterior compartment of the leg between tibialis anterior and extensor digitorum longus.
origin: anterior surface of the middle portion of the fibula and the interosseous membrane
insertion: the dorsal side of the base of the distal pha...