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 ...
The Coyle's view of the elbow is an axial projection that is performed in addition to the standard elbow series when there is suspicion of a radial head fracture 1-3. The projection isolates the radial head using a modified radiographic technique.
patient is sitting next to th...
Elbow dislocation is the second most common large joint dislocation in the adult population.
A dislocation with no fracture is simple which only requires close reduction whereas an accompanying fracture makes the dislocation complex usually requiring surgical intervention. The mo...
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 ...
The elbow external oblique view is an additional projection of the elbow often used to better demonstrate the radial head free from superposition.
patient is seated alongside the table
the fully extended arm and forearm, in a supinated position, are kept in contact with the t...
The inferior-superior elbow view is a modified elbow projection for patients in acute flexion greater than 90 degrees, it is also an additional projection to better demonstrate the olecranon process.It is comprised of two views demonstrating the distal humerus and proximal forearm structures
An elbow joint effusion is a key finding to recognize 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...
The elbow medial oblique view is a specialized projection, utilized to demonstrate both the coronoid process in profile and the olecranon process sitting within the olecranon fossa of the humerus.
the patient is seated alongside the table
fully extended arm and forearm, in a ...
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.
R: radial head
I: internal epicondyle
E: external epicon...
This is a basic article for medical students and other non-radiologists
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 mi...
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 utilized for specific indications.
Elbow x-rays are indicate...
This is a basic article for medical students and other non-radiologists
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 i...
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 edematous and disfigured lower extremities, d...
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
Empty notch sign is a direct sign of avulsion of the anterior cruciate ligament (ACL) tear at its femoral attachment. It denotes a fluid signal at the expected ACL attachment site at the intercondylar notch (fossa) on axial and coronal fluid-sensitive MR images.
The proximal ACL is the second m...
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, also known as chondromas 7, are relatively common intramedullary cartilage neoplasms with benign imaging features. They share histologic features with low-grade chondrosarcoma, and are sometimes classified under the umbrella term low grade chondral series tumors.
Enchondromatosis, also known as Ollier disease (see Terminology section), is a non-hereditary, sporadic, skeletal disorder characterized by multiple enchondromas principally located in the metaphyseal regions.
Some authors make a distinction between Ollier disease and enchondromato...
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 centers) 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 orthopedic 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 tumor grade, local spread and metastatic disease of malignant musculoskeletal tumors.
It does not classify skull tumors or marrow-originating tumors (e.g. lymphoma, plasmacytoma / multiple myeloma, Ewing sarcoma) 1...
Enostoses, also known as bone islands, are common benign sclerotic bone lesion which usually represent incidental findings. 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’t touch...
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), also known as a footprint, generally refers to the anatomic junction where connective tissue (e.g. ligaments, tendons, joint capsules) attach to bone.
Enthesis are commonly classified into two types 1:
In a fibrous enthes...
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 generalized inflammatory condition. Enthesitis is associated with the HLA-B27 inflammatory arthritides such as ankylosing spo...
Enthesopathy, also known as insertional tendinopathy, is a general term referring to a disorder affecting the site of tendon, ligament, or other soft tissue attachment to bone or enthesis.
Enthesopathy caused by an inflammatory condition, e.g. an inflammatory arthritis, may be more...
Enthesophytes (or enthesiophytes) are bony proliferations (spurs) that develop at an enthesis, that is at the attachment of a ligament, tendon or articular capsule onto bone. They are oriented along the direction of pull and develop in response to repetitive mechanical stress or a more generaliz...
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 edema and skin ind...
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 characterized 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 anesthesiologists.
Epidural lipomatosis refers to an excessive accumulation of fat within the spinal epidural space resulting in compression of the thecal sac. In severe cases, compression may be symptomatic. The lumbar region is most frequently affected.
The demographics of affected individuals ref...
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 tumors and other pathologies that occur around the epiphysis and any epiphyseal equivalent bone.
Common differential diagnoses include 2-4:
chondroblastoma: rare epiphyseal tumor found in young adults; it usually does not extend into the meta...
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 a spur seen in skeletally mature individuals arising at the level of closed epiphyseal line. It may be seen in any 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
Erlenmeyer flask deformity (EFD) (also known as metaphyseal flaring) refers to a radiographic appearance typically on a femoral radiograph demonstrating relative constriction of the diaphysis and flaring of the metaphysis.
It has been classically used with reference to the distal ends of the fe...
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 dise...
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 a comminuted fracture of the radial head accompanied by dislocation of the distal radioulnar joint. The force of trauma is transmitted down the forearm through the interosseous membrane causing disruption. The distal radioulnar joint injury may be mi...
Recurrent bone tumors 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 (characteristi...
Ewing sarcomas are the second most common malignant primary bone tumors of childhood after osteosarcoma, typically arising from medullary cavity with invasion of the Haversian system. They usually present as moth-eaten destructive permeative lucent lesions in the shaft of long bones with large s...
Ewing sarcoma family of tumors (ESFT), also referred as Ewing sarcomas of the chest wall, are malignant tumors affecting children and young adults, originating either from the osseous structures or the soft tissues of the chest wall.
On imaging, they are usually characterized as a large extrap...
Excessive lateral pressure syndrome (ELPS) or patellar compression syndrome 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 and adults.
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 teardrop 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. Extension ...
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 carpi 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-osseous...
Extensor carpi ulnaris (ECU) tendinopathy is varied and includes tendinosis, (stenosing) tenosynovitis, tendon instability and rarely rupture.
Athletes at increased risk of ECU tendinopathy include those who participate in 1,2:
racquet sports, e.g. tennis
club sports, e.g. golf...
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...
The extensor indicis muscle is an accessory extensor of the 2nd digit. It is located in the deep layer of the posterior compartment of the forearm and its tendon passes through the 4th extensor compartment of the wrist.
origin: posterior surface of the ulna (distal to extensor pollicis...
The extensor mechanism of the knee comprises:
medial patellar retinaculum
lateral patellar retinaculum
extensor mechanism of the knee injuries
Extensor mechanism of the knee injuries include:
quadriceps muscle tears
quadriceps tendon rupture
patellar tendon rupture
patellar dislocation often with medial retinaculum tears
patellar sleeve fractures
Extensor pollicis brevis (EPB) is one of the muscles of the deep layer of the posterior compartment of the forearm, inserting into the base of the proximal phalynx of the thumb. Along with extensor pollicis longus, it is responsible for extension of the thumb. Along with abductor pollicis longus...
Extensor pollicis longus (EPL) is a muscle of the deep compartment in the posterior compartment of the forearm. It passes through the 3rd extensor compartment of the wrist, then continues laterally towards the thumb around Lister's tubercle. The tendon of EPL defines the ulnar border of the Anat...
The extensor retinaculum is located at the dorsal aspect of the foot and consists of the superior and inferior extensor retinacula.
The superior extensor retinaculum is located proximally to the dorsal aspect of the ankle joint and houses the tibialis anterior, extensor digitoru...
The external (or outermost) intercostal muscles are important muscles of respiration. They number eleven on each side and are located in the intercostal space, expanding the transverse dimension of the thoracic cavity during inspiration.
The external intercostal muscles are the o...
The external oblique muscle (EOM) is one of the muscles that forms the anterior abdominal wall. Its free inferior border forms the inguinal ligament, and its aponeurotic part contributes to the anterior wall of the inguinal canal.
origin: outer surface of the shaft of the lower 8 ribs...
Extra-articular lateral hindfoot impingement syndrome refers a non-traumatic cause of ankle impingement. This can include talocalcaneal, subfibular, and /or talocalcaneal-subfibular impingements.
It presents as the sequela of a pathological tibialis posterior tendon, which causes pes planus (fl...
Extraskeletal chondrosarcomas make up only 2% of soft-tissue sarcomas and only 1% of all chondrosarcomas.
They tend to be of higher grade than run-of-the-mill conventional intramedullary chondrosarcomas, with the majority being of the myxoid (most common) or mesenchymal varieties 3...
Extraskeletal Ewing sarcoma (EES) is included in the Ewing sarcoma family of tumors (ESFT) along with Ewing sarcoma of bone, primitive neuroectodermal tumor (PNET), peripheral neuroepithelioma, and thoracopulmonary PNET (Askin tumor). When compared with Ewing sarcoma of bone, extraskeletal Ewing...
Knowing extraskeletal musculoskeletal lesions by compartment is useful to help generate a meaningful differential diagnosis:
extraskeletal myxoid chondrosarcoma
Extraskeletal osteosarcoma (ESOS) is a rare mesenchymal malignant tumor that occurs in the retroperitoneum and soft tissue of extremities without any attachment to bone.
Extraskeletal osteosarcoma in contrast to other subtypes of osteosarcoma occurs infrequently in individuals und...
The extrusion index is a radiographic measurement of femoral head bony coverage by the acetabulum. It is useful in assessing for developmental dysplasia as well as femoroacetabular impingement.
It is calculated by dividing the horizontal distance of the lateral femoral head that is uncovered by...
The fabella is an accessory ossicle typically found in the lateral head of the gastrocnemius. It occurs in ~20% (range 10-30%) of the population 1.
The fabella can also be fibrocartilaginous in nature and is occasionally found in the medial head of the gastrocnemius. The fabella articulates wi...