Baumann angle, also known as the humeral-capitellar angle, is used for the evaluation of the displacement of pediatric supracondylar humeral fractures. It is measured on a frontal radiograph, with elbow in extension.
This angle is formed by the humeral axis and a straight line through the epi...
Baxter neuropathy is a nerve entrapment syndrome resulting from the compression of the inferior calcaneal nerve (Baxter nerve).
heel pain with maximal tenderness over the course of the inferior calcaneal nerve (on the plantar medial aspect of the foot and anterior to the ...
Bayonet deformity is a term used to describe the shape of the wrist in certain conditions:
hereditary multiple exostosis with pseudo-Madelung deformity
retarded bone growth of the distal ulna with outward bowing of the radius with distal radioulnar joint subluxation
Becker muscular dystrophy (BMD) is a dystrophinopathy that is considered to be a milder form of Duchenne muscular dystrophy.
It may be present in 3 to 6 per 100,000 male births. The condition is extremely rare in females due to its inheritance pattern, as discussed below.
Benign fibrous histiocytoma is closely related to fibroxanthoma of bone, is a rare lesion usually occurring in the skin where it is known as dermatofibroma.
Typically presents with pain, and most often in the third decade.
Only a few case reports have been pub...
Benign lytic bone lesions encompass a wide variety of entities. A useful starting point is the FEGNOMASHIC mnemonic.
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A mnemonic to remember five benign lytic lesions that rarely occur in patients over 30 years old
S: simple bone cyst
A: aneurysmal bone cyst
N: non-ossifying fibroma
E: eosinophilic granuloma
In a patient older than 30 years old these different...
Benign notochordal cell tumors are vertebral lesions that are usually asymptomatic and discovered incidentally on imaging of the head or spine. As this is a poorly-recognized entity, it can often be confused with aggressive vertebral lesions, such as a chordoma, when it is seen on imaging.
A Bennett fracture is a fracture of the base of the thumb resulting from forced abduction of the first metacarpal. It is defined as an intra-articular two-part fracture of the base of the first metacarpal bone.
two piece fracture of the base of the thumb...
Bennett lesions of the shoulder, also called thrower's exostosis refers to the mineralization of the posterior band of the inferior glenohumeral ligament.
The abnormality is more prevalent in overhead throwing athletes.
It is associated with posterior labral tears,...
Bent bone dysplasias are a class of dysplasia included in a 2010 classification of genetic skeletal disorders 1.
kyphomelic dysplasias, a diverse class, including
congenital bowing of the long bones
cartilage-hair hypoplasia (CHH; metaphyseal d...
Berndt and Harty classification is used for osteochondral lesions of the talus.
stage I: subchondral bone compression (marrow edema)
stage IIa: subchondral cyst
stage IIb: incomplete separation of fragment
stage III: complete separation but no displacement
Bernese periacetabular osteotomy, also known as Ganz osteotomy, is an orthopedic procedure involving osteotomy surrounding the acetabulum and subsequent angulation to improve coverage of the femoral head by the acetabulum. It is performed in the context of hip dysplasia. There is an osteotomy th...
Bertolotti syndrome refers to the association between lumbosacral transitional vertebrae and low back pain.
Although it may be a consideration in younger patients, the entity is considered controversial and has been both supported and disputed since the Italian radiologist Mario Bertolotti (187...
The beta angle is a measurement used in the ultrasonographic assessment of developmental dysplasia of the hip (DDH).
It is defined as the angle formed between the vertical cortex of the ilium and the triangular labral fibrocartilage (echogenic triangle) and thus reflects the femoral head cartil...
The biceps brachii muscle (also known simply as biceps) is a two-headed muscle in the anterior compartment of the arm that flexes at the elbow and supinates the forearm.
short head: coracoid process of the scapula
long head: supraglenoid tubercle of the scapula
Biceps brachii rupture can occur at either superior or inferior attachment but most commonly involves the long head at its proximal origin at the superior glenoid labrum. Rupture of the distal biceps rupture causes weakness when supinating the forearm. It is therefore associated with significant...
Biceps chondromalacia is an attritional lesion of the humeral head caused by repeated abrasion by the intra-articular segment of the long head of biceps tendon.
The long head of biceps brachii arises from the supraglenoid tubercle of the glenoid fossa and has an intra- and extra-arti...
The biceps femoris is one of the large muscles in the posterior compartment of the thigh and a component of the hamstrings. It has a long and a short head, each with different functions and innervation.
Its medial border forms the superolateral border of the popliteal fossa.
The biceps pulley is a capsuloligamentous complex that stabilizes the long head of biceps tendon within the bicipital groove. It comprises the coracohumeral ligament, superior glenohumeral ligament, and distal attachment of the subscapularis tendon. It is located within the rotator interval betw...
Biceps pulley injuries can be challenging and difficult to diagnose. They can be missed during open and arthroscopic examination, and therefore have sometimes been referred to as a “hidden lesions”.
Anterior extension of supraspinatus tendon tears may involve the rotator interval cap...
The bicipitoradial bursa is located between the distal biceps brachii tendon and the tuberosity of the radius. The bursa partially or completely wraps around the biceps tendon. It ensures frictionless motion between the biceps tendon and the proximal radius during pronation and supination of the...
Bicipitoradial bursitis refers to inflammation of the bicipitoradial bursa.
The bicipitoradial bursa surrounds the biceps tendon in supination. In pronation, the radial tuberosity rotates posteriorly, which compresses the bicipitoradial bursa between the biceps tendon and the radial cortex, wh...
The median nerve may divide into two nerve bundles in
the distal forearm and appear as a bifid median nerve in the carpal tunnel. It has an incidence of ~3%.
The median nerve usually divides into two or three branches after exiting the distal edge of the transverse carpal ligament that covers...
Bifid or forked or bifurcated rib is a congenital skeletal abnormality of the rib cage with the cleaved sternal end into two. They are thought to occur in ~0.2% of the population and there may be a female as well as right-sided predilection 2.
Bifid ribs can be seen ...
The bifurcate ligament arises from the anterior process of the calcaneus as a single band and divides into calcaneocuboid (lateral) and calcaneonavicular (medial) parts forming a Y-shape.
A bilateral facet dislocation is an unstable flexion distraction type of dislocation of the cervical spine, often a result of buckling force. Occasionally, the bilateral facet dislocation has been named a 'doubly-locked' vertebral injury giving the impression of stability. However, due to comple...
Bilateral thinning of the parietal bones, also known as biparietal osteodystrophy, is an uncommon, slowly progressive acquired disease of middle-aged people with slight female predilection. It is typically an incidental finding.
The etiology is unknown but is thought to be an age-re...
A bipartite medial cuneiform is an anatomical variant where there are two ossification centers involving the medial cuneiform. In many cases the overall shape of the medial cuneiform is conserved, although the size of the two combined bones is larger than that of a normal medial cuneiform.
A bipartite patella (two-part patella) is a patella with an unfused accessory ossification center at the superolateral aspect.
The superolateral accessory ossification center of the patella is usually present by 12 years of age and may persist into adult life. Prevalence of a bipa...
A bipartite scaphoid is a rare example of a divided carpus. There is controversy whether this condition is congenital (i.e. normal variant) or post-traumatic. Bipartite scaphoids may be unilateral or bilateral.
Diagnostic criteria have been proposed 3:
no history of traumatic injury
Birth fractures of the clavicle occur in 0.5-1% of vaginal deliveries and are the most frequent birth-related fracture. They are most commonly seen following normal, uncomplicated births but there is recognized increased incidence with high birth weight babies, forceps delivery and shoulder dyst...
Birth trauma relates to those conditions caused by both physical/mechanical and hypoxic injuries.
Birth trauma occurs in ~5 per 1000 births 2.
Bizarre parosteal osteochondromatous proliferations (BPOP), also known as a Nora lesions, are benign exophytic osteochondral lesions which have an appearance similar to an osteochondroma and are typically seen in the hands and feet.
On imaging, BPOPs are shown to be continuous with the underly...
The Blackburne-Peel ratio is an alternative to Insall-Salvati ratio and is used to assess patellar height, and determine the presence of patella baja or patella alta.
A lateral radiograph of the knee with 30 degrees of flexion is obtained, and a horizontal line at the level of the tibial platea...
The blade of grass sign, also called the candle flame sign, refers to the lucent leading edge in a long bone seen during the lytic phase of Paget disease of bone.
The blade of grass sign is characteristic of Paget disease of bone. This is akin to osteoporosis circumscripta cranii seen in the s...
Blade plates, also known as angled blade plates, are a type of orthopedic hardware used for reconstructing subtrochanteric femoral fractures, including therapeutic fractures during derotational osteotomies.
Blade plates were an advance on earlier fixation nails such as the Y nail or the Zicker ...
Block vertebra is a type of vertebral anomaly where there is a failure of separation of two or more adjacent vertebral bodies. It is an anatomic variant.
In a block vertebra, there is partial or complete fusion of adjacent vertebral bodies.
Bloom syndrome is a rare autosomal recessive disorder characterized by short stature, brachydactyly, malar hypoplasia and facial telangiectasia, erythema and cafe au lait spots. Affected individuals have an increased risk of developing malignancies.
There is extreme chromosomal fragi...
Blount disease refers to a local disturbance of growth of the medial aspect of the proximal tibial metaphysis and/or epiphysis that results in tibia vara. The condition is commonly bilateral.
There is no recognized inheritance pattern.
Clinically, the chi...
Blow out bone metastases or expansile bone metastases are typically only encountered in a relatively small number of primary malignancies, including 1:
renal cell carcinoma
Occasionally the sclerotic metastases of prostate cancer may also be expansile ...
Blumensaat line, also known as the intercondylar line, is the line drawn along the roof of the intercondylar notch of the femur on sagittal view of the knee.
It can been used for:
indicating relative position of patella - normally intersects the lower pole of the patella
evaluating for ACL in...
A Bochdalek hernia (plural: hernias or herniae) is a form of congenital diaphragmatic hernia. They occur posteriorly and are due to a defect in the posterior attachment of the diaphragm when there is a failure of pleuroperitoneal membrane closure in utero. Retroperitoneal structures may prolapse...
Body imaging is the term assigned to cross-sectional imaging of the body, which radiologically refers to the chest, abdomen and pelvis. It is often used by radiologists who report this region (sometimes known as body imagers/radiologists) to differentiate their primary area of interest from othe...
The body of the sphenoid bone is the midline cubical portion of the sphenoid bone, hollowed by the sphenoid air sinuses.
The body has superior, inferior, anterior, posterior, and lateral surfaces.
The superior surface features:
ethmoidal spine: prominent spine that articulates...
Böhler angle, also written as Bohler angle or Boehler angle, is also called the calcaneal angle or tuber joint angle 1, and is the angle between two lines tangent to the calcaneus on the lateral radiograph. These lines are drawn tangent to the anterior and posterior aspects of the superior calca...
Bone age assessment is used to radiologically assess the biological and structural maturity of immature patients from their hand and wrist x-ray appearances. It forms an important part of the diagnostic and management pathway in children with growth and endocrine disorders. It is helpful in the ...
The bone age, hand and wrist PA is a commonly performed examination to determine the radiographic age of the patient via the assessment of growth centers
patient is seated alongside the table
the non-dominant hand is placed, palm down on the image receptor
shoulder, elbow, a...
Bone (marrow) contusion (also known as bone bruising) is an osseous injury which may result from compression of bone structures.
Bone contusions represent trabecular microfractures with hemorrhage and without a discrete fracture line or contour abnormality 4. They typically appear wi...
A mnemonic for bony cortical lesions is:
Fear Of Missing Out S
O: osteoid osteoma
S: stress fracture
Conditions associated with bone deformity from softening includes:
bowing of long bones
biconcave vertebral bodies / codfish vertebra
Bone-forming tumors are a subset of bone tumors that are characterized by their propensity to form excess osteoid. They can be further subdivided into benign and malignant tumors.
bone island (enostosis)
Bone infarction is a term used to refer to osteonecrosis within the metaphysis or diaphysis of a bone. Necrosis is a type of cell death due to irreversible cell injury, which can be recognized microscopically by alterations in the cytoplasm (becomes eosinophilic) and in the nucleus (swelling, py...
There are several bony lesions that can involve or produce a sequestrum.
Brodie abscess: osteomyelitis
certain soft tissue tumors (with bony extension)
malignant fibrous histiocytoma
metastasis (especially from breast ca...
Bone macroscopic structure allows a bone to be divided into regions based on position or morphology. This is important for a number of reasons including how growth may be affected by injury.
Bones can be separated into:
Normal bone marrow is divided into red and yellow marrow, a distinction made on the grounds of how much fat it contains.
Red marrow is composed of:
reticulum (phagocytes and undifferentiated progenitor cells)
scattered fat cells
a rich v...
Bone marrow edema is the term given to abnormal fluid signal seen within the bone marrow on MRI. It is a non-specific, yet important finding usually indicating the presence of an underlying pathology.
There is a long (long) list of possible causes of this finding:
Bone marrow edema syndrome refers to a group of transient, self-limiting clinical entities of unknown cause, which are associated with the presence of bone marrow edema pattern.
These conditions include:
transient osteoporosis of the hip
regional migratory osteoporosis
reflex sympathetic dys...
Bone marrow edema syndrome of the foot and ankle, also known as transient bone marrow edema syndrome of the foot and ankle, refers to the presence of self-limited, patchy bone marrow T2 hyperintensities in the bones of the ankle and/or foot of unknown etiology. It is related to transient osteopo...
Bone mineral density (BMD) is defined as the amount of mineral (calcium hydroxyapatite) per unit of bone.
BMD can be measured by various methods with DEXA the most prevalent
gamma rays: replaced by radiographic methods
single-energy photon absorptiometry (SPA) was super...
Bone scans are a nuclear medicine (scintigraphic) study that makes use of Technetium 99m (commonly Tc99m-methylene diphosphonate (MDP)) as the active agent.
The study has three phases which follow intravenous injection of the tracer. Sometimes a fourth (delayed/delayed) phase is performed.
The bones in the lower limb can be divided into those within the thigh and leg (4) and those within the foot (26).
Bones of the thigh and leg
Bones of the foot
The bones in the upper limb can be divided into those within the arm and pectoral girdle (3), forearm (2) and wrist and hand (27). There are also a number of accessory ossicles, predominantly occurring at the wrist.
Bones of the arm and pectoral girdle
Bones of the...
There are many types of bone within the body:
long bones (longer than they are wide)
short bones (not long bones)
sesamoid bones (for within a tendon)
irregular bones (don't fit into a category)
The majority of the bones of the appendicular skeleton are long bones. However, the ...
There are a bewildering number of bone tumors with a wide variety of radiological appearances:
Bone within a bone is a descriptive term applied to bones that appear to have another bone within them. There are numerous causes including:
thoracic and lumbar vertebrae (neonates and infants)
growth recovery lines (after infancy)
cortical splitting and new periostitis
sickle cell d...
A useful mnemonic to remember the possible etiologies of a bone within a bone appearance is:
G: growth arrest lines
H: heavy metals, hypoparathyroidism, hypothyroidism
S: sickle cell anemia, scurvy, syphilis
T: thalassemia, tuberculosis
D: disease o...
Bony humeral avulsion of the glenohumeral ligament (BHAGL) lesion is just like its slightly shorter relative HAGL lesion, except as the name suggests a bony avulsion fracture is seen at humeral insertion of the inferior glenohumeral ligament.
It is often associated with a subscapularis tear, an...
A mnemonic to help remember bony lesions that have no pain or periostitis is:
F: fibrous dysplasia
U: unicameral bone cyst
N: non-ossifying fibroma
If periostitis or pain is present (assuming no trauma, which can be a foolhardy assumption), you can exclude E ...
The bony pelvis is formed by the sacrum and coccyx and a pair of hip bones (os coxae or innominate bones), comprising the ischium, pubis and ilium and are part of the appendicular skeleton.
Its primary function is the transmission of forces from the axial skeleton to the lower limbs as well as...
The radiological definition of a bony sequestrum refers to an image of calcification within a lucent lesion, completely separated from the surrounding bone and without referring to the histological nature and vascular status of the calcified tissue 1.
The pathological definition of a sequestru...
Mnemonics to help remember common causes of bony sequestrum include:
E: eosinophilic granuloma
I: infection (Brodie abscess)
L: lymphoma (skeletal)
M: malignant fibrous histiocytoma or metastasis (especially from breast carcinoma)
The skeleton is the complete set of bones that make up a human. There are 206 bones in total which can be divided into:
The proximal femur has four major groups of trabeculae, distributing the compressive and tensile forces from the femoral head into the femoral diaphysis through the femoral neck. Together these trabeculae create the Ward triangle. The individual trabecular groups include:
principal compressive ...
Boogard's angle is measured by drawing a line from basion to opisthion and another line along the plane of the clivus to the basion intersecting the first line - the angle between these two lines is measured.
The normal angle is 126° +/- 6°. If the angle measures more than 136° it is indicative...
Boomerang sign may refer to:
boomerang sign (peroneus brevis tear)
boomerang sign (medial meniscal tear)
boomerang sign (splenium)
History and etymology
Boomerang is of course a curved projectile used originally by the Australian Aborigines, one of its various uses was as a hunting weapon 1.
The boomerang sign is defined as a small displaced flap from a longitudinal horizontal type medial meniscal tear which is displaced inferiorly into the medial meniscotibial recess. The imaging diagnosis of this type of tear is crucial because it is normally hidden from the surgeon during routine...
Bornholm disease, also known as epidemic pleurodynia, is a virally-mediated myositis presenting as recurrent episodes of acute severe pleuritic pain. It is usually self-limiting, and serious morbidity is rare.
Its true incidence is unknown and it is thought that it is underdiagnos...
The term Bosworth fracture is no longer used. However, it was classically used to refer to a fracture-dislocation of the ankle in which there was fracture of the fibula and posterior dislocation of the talus.
History and etymology
Named after David M Bosworth (1897-1979), orthopedic surgeon fr...
This is a basic article for medical students and other non-radiologists
Both hands series (or both hands x-ray) is an investigation almost exclusively performed in the rheumatology service to assess patients with arthritis. It is not used in trauma.
This is a summary article...
Botryoid rhabdomyosarcoma, also known as sarcoma botryoides, is a type of embryonal rhabdomyosarcoma and accounts for 5-10% of all rhabdomyosarcomas 6.
It tends to occur in pediatric population, often between birth and 15 years of age 7.
Rhabdomyosarcomas generally ha...
Bouchard nodes are a clinical sign relating to bony nodules of the proximal interphalangeal joints and are much less common than Heberden nodes. They generally (but not always) correspond to palpable osteophytes.
They are sometimes painful, and are typically associated wi...
Boutonniere deformity is one of the musculoskeletal manifestations of rheumatoid arthritis in the hand with:
flexion contracture of the proximal interphalangeal (PIP) joints
extension of the distal interphalangeal (DIP) joints
The defect appears in the tendon which splays open. The appearanc...
Bowdler spurs refer to transverse long bone midshaft spurs or osteochondral projections associated with hypophosphatasia. They typically occur in the fibulae and less commonly in the forearms.
Bowing fractures are incomplete fractures of tubular long bones in pediatric patients (especially the radius and ulna) that often require no intervention and heal with remodelling.
Bowing fractures are almost exclusively found in children. However, there have been several case rep...
Boxer fractures are minimally comminuted, transverse fractures of the 5th metacarpal and are the most common type of metacarpal fracture. They typically occur (as the name suggests) when punching and are a common sight in all emergency departments on Friday nights.
They should not be confused w...
Boxer knuckle (not to be confused with a Boxer fracture) refers to an appearance when there is a disruption to the sagittal bands of the extensor hood, particularly over the metacarpophalangeal (MCP) joint.
It often tends to result when a clench fisted hand strikes an object in a tra...
Boyd amputation refers to amputation at the level of the ankle with preservation of the calcaneus and heel pad and consequent fixation of the calcaneus to the tibia. It allows for complete weight bearing and provides both stabilization of the heel pad and suspension for a prosthesis.
The brachialis muscle (brachialis) is one of the three muscles of the anterior compartment of the arm. It is only involved in flexion at the elbow and therefore the strongest flexor at the elbow, compared with the biceps brachii which is also involved in supination because of its insertion on th...
Brachial plexitis refers to inflammatory change involving the brachial plexus. This is in contrast to a brachial plexopathy meaning any form of pathology involving the brachial plexus.
Brachial plexitis is more commonly seen in men between 30 and 70 years of age and is bilateral i...
The brachial plexus is a complex neural network formed by lower cervical and upper thoracic ventral nerve roots which supplies motor and sensory innervation to the upper limb and pectoral girdle. It is located in the neck extending into the axilla posterior to the clavicle.
Brachial plexus injuries are a spectrum of upper limb neurological deficits secondary to partial or complete injury to the brachial plexus, which provides the nerve supply of upper limb muscles.
Trauma, usually by motor vehicle accidents, involves severe traction on the ...
A useful mnemonics for brachial plexus terminal branches includes:
Most Alcoholics Must Really Urinate
Where the first letter of each word represents the terminal branches of the brachial plexus:M: musculocutaneous nerveA: axillary nerveM: median nerveR: radial nerveU: ulnar nerve