Articles

Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.

2,850 results found
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Toddler fracture

Toddler fractures are minimally or undisplaced spiral fractures usually of the tibia, typically encountered in toddlers. It is a potentially difficult diagnosis to establish on account of both the symptoms and imaging findings being subtle. Terminology The term has sometimes also been used to ...
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Anterior inferior iliac spine avulsion injury

Anterior inferior iliac spine (AIIS) avulsion injuries are one of the six main types of pelvic apophyseal avulsion fractures. Subacute or chronic avulsion injuries can be mistaken for a pseudotumour.  Epidemiology As with many pelvic avulsion injuries, they most often occur in adolescents (mos...
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Brodie abscess

Brodie abscess is an intraosseous abscess related to a focus of subacute pyogenic osteomyelitis. Unfortunately, there is no reliable way radiographically to exclude a focus of osteomyelitis. It has a protean radiographic appearance and can occur at any location and in a patient of any age. It mi...
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Long head of biceps tendon dislocation

Dislocation of the long head of biceps tendon is one of the complications of shoulder injury. The long head of biceps (LHB) tendon is usually located inferiorly in the bicipital groove held there by the transverse humeral ligament. As it moves superiorly it arches through the rotator cuff interv...
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Ainhum

Ainhum, also known as dactylolysis spontanea, is a rare cutaneous condition in which a hyperkeratotic band partially or totally encircles a digit. The constriction thins the underlying bone, which is then prone to fracture. Some cases result in autoamputation. Epidemiology Some have suggested ...
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Bankart lesion

Bankart lesions are injuries specifically at the anteroinferior aspect of the glenoid labral complex, and represent a common complication of anterior shoulder dislocation. They are frequently seen in association with a Hill-Sachs lesion.  Terminology Strictly speaking, a "Bankart lesion" refer...
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Brachial plexus

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. Summary origin: ven...
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Inferior lumbar triangle

The inferior lumbar triangle, also known as the Petit triangle, is an anatomical space through which inferior lumbar hernias can occur. Gross anatomy Boundaries inferiorly: iliac crest anteriorly: external oblique muscle  posteriorly: latissimus dorsi muscle floor: internal oblique muscle ...
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Mallet finger

Mallet finger describes a type of injury where there is disruption of the extensor mechanism of the finger at the distal interphalangeal joint (DIP). It is the most prevalent finger tendon injury in sport. The term includes both bony avulsion injury and tendinous injury without avulsion.  Clini...
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Volar plate avulsion injury

Volar plate avulsion injuries are a type of avulsion injury. The volar plate of the proximal interphalangeal (PIP) joint is vulnerable to hyperextension injury, in the form of either a ligament tear or an intra-articular fracture. Gross anatomy The volar plate forms the floor of PIP joint sepa...
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Developmental dysplasia of the hip

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. There is a clear female predominance, and it usually occurs from lig...
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SADDAN syndrome

SADDAN syndrome is an acronym for severe achondroplasia with developmental delay and acanthosis nigricans. It is an extremely rare condition, and as the name states, comprises a combination of skeletal, brain and cutaneous anomalies. Pathology Genetics The syndrome results from a mutation in ...
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Non-accidental injuries

Non-accidental injuries (NAI) represent both ethical and legal challenges to treating physicians. Radiologists are often the first to suspect NAI when confronted with particular injury patterns, and a knowledge of these is essential if the opportunity to save a child from future neglect is not ...
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Cleidocranial dysostosis

Cleidocranial dysostosis (CCD), also known as cleidocranial dysplasia, is a rare skeletal dysplasia with predominantly membranous bone involvement, which carries an autosomal dominant inheritance 4. Clinical presentation large head, with large fontanelles with delayed closure broad mandible ...
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Complications of hip joint replacements

Complications of hip joint replacements are common and are essential for the radiologist to be aware in the assessment of the radiographs with hip prostheses. They are many and can occur at various time intervals following the initial surgery: aseptic loosening: considered to be the most common...
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Lambert-Eaton myasthenic syndrome

Lambert-Eaton myasthenic syndrome (LEMS) is a rare neuromuscular junction disorder of paraneoplastic or primary autoimmune etiology. Epidemiology LEMS is the second most common neuromuscular junction disease after myasthenia gravis.  Two-thirds of LEMS present as a paraneoplastic syndrome sec...
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Sacroiliac joint disease (differential)

Sacroiliitis (inflammation of the sacroiliac joint) can be a manifestation of a wide range of disease processes. The pattern of involvement is helpful for narrowing down the differential diagnosis. Usually bilateral and symmetrical  enteropathic arthritis​ Crohn disease ulcerative colitis a...
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Polysyndactyly

Polysyndactyly refers to the combined presence of polydactyly as well as syndactyly involving either the hands or feet. Polysyndactyly can be associated with a number of syndromes which includes: acrocephalopolysyndactylies (GCPS) type I: Noack syndrome type II: Carpenter syndrome (typically...
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Cutaneous and subcutaneous metastases

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. Pathology These metastases can come from haematogenous or lymphatic spre...
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Plantar fasciitis

Plantar fasciitis refers to inflammation of the plantar fascia of the foot. It is considered the most common cause of heel pain. Clinical presentation  Pain on the undersurface of the heel on weight-bearing is the principal complaint. It can be worse when weight is borne after a period of rest...
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Superior lumbar triangle

The superior lumbar triangle, also known as the triangle of Grynfeltt-Lesshaft, is one of the locations for a lumbar hernia. Gross anatomy Boundaries medially: the quadratus lumborum muscle  superiorly: twelfth rib   laterally: internal oblique muscle floor: transversalis fascia and the ap...
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Haglund deformity

Haglund deformity, also known as a pump bump, Bauer bump, or Mulholland deformity, is defined as bony enlargement formed at posterosuperior aspect of the calcaneum. This deformity leads to retrocalcaneal bursitis. Pathology It may result secondary to chronic pressure of rigid shoes. Radiograp...
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Retrocalcaneal bursitis

Retrocalcaneal bursitis refers to inflammation of the retrocalcaneal bursa, which lies between the antero-inferior calcaneal tendon and posterosuperior calcaneus. It forms part of Haglund syndrome.  Please, note that two bursae lie near the calcaneal tendon insertion: the retrocalcaneal bursa (...
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Technetium 99m-methyl diphosphonate

Technetium 99m-methyl diphosphonate (99mTc MDP) is a radiotracer used in nuclear medicine especially for bone scans. Any disease process which results in extracellular fluid expansion will lead to accumulation of this tracer. Radionuclide profile photon energy: 140 keV physical half life: 6 h...
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Latarjet procedure

The Latarjet procedure is an orthopaedic procedure in the shoulder where a coracoid bone block is positioned flush with the anterior-inferior border of the glenoid (often with one or more screws). It can be performed as either an open or arthroscopic procedure. It is usually performed for antero...
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Lymph node enlargement

Lymph node enlargement (rarely lymphadenomegaly) is often used synonymously with lymphadenopathy, which is not strictly correct. Terminology Lymphadenopathy (or adenopathy) is, if anything, a broader term, referring to any pathology of lymph nodes, not necessarily resulting in increased size; ...
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Calcaneal tuberosity avulsion fracture

Avulsion fractures of the calcaneal tuberosity are rare, accounting for only 3% of all calcaneal fractures. Pathology There are three mechanisms of action 4: fall during plantarflexion ankle hyperextension feet fixed on the ground with sudden muscular contraction Associations There is a s...
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Avulsion injuries

Avulsion injuries or fractures occur where the joint capsule, ligament, tendon or muscle attachment site is pulled off from the bone, usually taking a fragment of cortical bone. There are numerous sites at which these occur. Being familiar with them is important as subacute/chronic injuries can ...
Article

Avascular necrosis of the hip

Avascular necrosis of the hip is more common than other sites, presumably due to a combination of precarious blood supply and high loading when standing.  Clinical presentation The most common presenting symptom is a pain in the region of affected hip, thigh, groin, and buttock. Although few p...
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Medical devices in the abdomen and pelvis

Medical devices in the abdomen and pelvis are important to be recognised, just like medical devices of the chest. Often we ignore these devices, considering them to be incidental and non-pathological, however it is essential to be aware of potential complications. Gastrointestinal tubes stomac...
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Magnetic resonance neurography

Magnetic resonance neurography (MRN) is a relatively new non-invasive imaging technique for dedicated assessment of peripheral nerves. It is used to assess peripheral nerve entrapments and impingements as well as localization and grading of nerve injuries and lesions. Dedicated high-resolution...
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Multiple myeloma

Multiple myeloma is the most common primary malignant bone neoplasm in adults. It arises from red marrow due to monoclonal proliferation of plasma cells and manifests in a wide range of radiographic abnormalities. Multiple myeloma remains incurable. Terminology Four main patterns are recognise...
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Soft tissue chondroma of the Hoffa fat pad

Soft tissue chondroma of the Hoffa (infrapatellar) fat pad is a rare form of chondroma. It is considered by some to be the end-stage of Hoffa disease of the infrapatellar fat pad.  Clinical presentation The condition usually presents in adults with chronic anterior knee pain as well as a hard ...
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Spontaneous osteonecrosis of the knee

Spontaneous osteonecrosis of the knee, also known as Ahlback disease, SONK or even SPONK, has similar appearances to osteochondritis dissecans of the knee but is found in an older age group. Epidemiology SONK is seen more frequently in women (M:F 1:3) and affects older patients, typically over...
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Crouzon syndrome

Crouzon syndrome is rare disorder characterised by premature craniosynostoses.  Pathology Features include: abnormal calvarial shape: in severe case can give a "cloverleaf skull"  shallow orbits with exopthalmos mid facial hypoplasia bifid uvula Genetics It carries an autosomal dominant ...
Article

Obesity

Obesity is defined as a body mass index (BMI) greater than 30 kg/m2. It is described as being a "modern epidemic" due to increased rates of metabolic syndrome and other complications in these patients, along with a high and increasing prevalence.  Epidemiology Obesity rates vary around the wor...
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Carpometacarpal joint dislocation

Carpometacarpal joint dislocations are uncommon dislocations of the hand. Epidemiology There is a strong younger male predominance. These injuries are more common in the dominant hand. Clinical presentation Typical mechanism: punching (most common) fall The patient may present with ulnar ...
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Lucent/lytic rib lesion (mnemonic)

Mnemonics for lucent/lytic rib lesions include: FAME FEMALE These are just short lists for the possible causes of a lucent/lytic rib lesion. The list of lucent/lytic bone lesions is far longer.  Mnemonics FAME F: fibrous dysplasia A: aneurysmal bone cyst (ABC) M: metastasis to bone / mul...
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Chondrosarcoma

Chondrosarcomas are malignant cartilaginous tumours that account for ~25% of all primary malignant bone tumours. They are most commonly found in older patients within the long bones and can arise de novo or secondary from an existing benign cartilaginous neoplasm. On imaging, these tumours have ...
Article

Ultrasound-guided biopsy

Ultrasound-guided biopsy is one form of image-guided biopsy, typically performed by a radiologist. It is the most common form of image-guided biopsy, offering convenience and real-time dynamic observation with echogenic markers on cannulae allowing for precise placement. It can potentially be u...
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Disc bulge

A disc bulge  represents displacement of the outer fibres of the annulus fibrosus beyond the margins of the adjacent vertebral bodies, involving more than one-quarter (25% or 90 degrees) of the circumference of an intervertebral disc 3. Because it is limited by the annulus fibrosus it does not e...
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Plantar fascial tear

Plantar fascial tears refer to disruption of plantar fascial fibres which can occur in associated with longstanding plantar fasciitis or those treated with steroid injections. The tears can be complete (i.e. rupture) or incomplete. Radiographic features MRI MR imaging features include: T1 a...
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Erosion of the odontoid process (differential)

Erosion of the odontoid peg can result from a number of pathological entities: inflammatory arthropathy rheumatoid arthritis: classic 1,2 systemic lupus erythematosus crystal arthropathy calcium pyrophosphate arthropathy (CPPD): relatively common gout non-inflammatory arthropathy: osteoar...
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Epibasal fracture of the thumb

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...
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Bennett fracture

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. Radiographic features Plain radiograph two piece fracture of the base of the thumb...
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Finger clubbing

Finger clubbing, also called "drumstick fingers", is a common clinical sign in patients with heart or lung disease. The term is used to describe an enlargement of the distal phalanges of the fingers, giving them a drumstick or club-like appearance.  Pathology The underlying pathogenesis of fin...
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Clear cell chondrosarcoma

Clear cell chondrosarcomas are a subtype of chondrosarcoma constituting 1-2% of all chondrosarcomas. They are typically low-grade (see chondrosarcoma grading) and get their name from the presence of clear cell chondrocytes which contain abundant vacuolated cytoplasm due to the presence of glycog...
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Poland syndrome

Poland syndrome refers to a congenital unilateral absence of the pectoralis major and minor muscles and is a recognised cause of unilateral hyperlucent hemithorax.  Epidemiology Poland syndrome is usually sporadic, although rare familial cases have been described 1. It is rare, with an estimat...
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Bochdalek hernia

A Bochdalek hernia 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 through the defect, e.g. ret...
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Ehlers-Danlos syndrome

Ehlers-Danlos syndrome comprises a heterogeneous group of collagen disorders (hereditary connective tissue disease). Epidemiology There is a recognised male predominance. Clinical presentation Clinically manifests by skin hyperelasticity and fragility, joint hypermobility and blood vessel fr...
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Dorsal defect of the patella

Dorsal defects of the patella are benign subchondral lesions of unknown aetiology and a normal developmental anomaly of the patella, which can be mistaken for a pathological process such as a focus of infection or osteochondritis dissecans. Epidemiology Dorsal defect of patella occurs in males...
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Avulsion fracture of the 5th metatarsal styloid

Avulsion fracture of the 5th metatarsal styloid, also known as a pseudo-Jones fracture or a dancer fracture, is one of the more common foot avulsion injuries and accounts for over 90% of fractures of the base of the 5th metatarsal. Despite what should be a simple entity, controversy exists, as ...
Article

Scheuermann disease

Scheuermann disease, also known as juvenile kyphosis, juvenile discogenic disease 11, or vertebral epiphysitis, is a common condition which results in kyphosis of the thoracic or thoracolumbar spine. The diagnosis is usually made on plain film. Epidemiology occurs in ~5% (range 0.4-8%) of the ...
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Lumbar Scheuermann disease

Lumbar Scheuermann disease is a type of variant Scheuermann disease where there is no abnormal kyphosis. This has been reported in the lumbar spine and thoracolumbar junction of patients of all ages, and back pain may be present. On imaging, affected individuals can have vertebral endplate chan...
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Apophysis of the proximal 5th metatarsal

The apophysis of the proximal 5th metatarsal lies laterally and is oriented longitudinally parallel to the shaft. Apophysis of the fifth metatarsal base appears on plain radiographs at age 12 for boys and 10 for girls. Fusion of the apophysis to the metatarsal base usually occurs within the fol...
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Skeletal sarcoidosis

Skeletal sarcoidosis is an uncommon manifestation of sarcoidosis. Epidemiology Skeletal involvement is thought to occur in ~1-13% of patients with sarcoidosis 6,9.  Osseous involvement may be more common in black patients 10. Clinical presentation Patients with large bone lesions and verteb...
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Sarcoidosis

Sarcoidosis is a non-caseating granulomatous multi-system disease with a wide range of clinical and radiographic manifestations.  Individual systemic manifestations are discussed in respective articles:  pulmonary and mediastinal manifestations cardiac manifestations  musculoskeletal manifes...
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Sarcoidosis (musculoskeletal manifestations)

Musculoskeletal manifestations of sarcoidosis occur in ~20% (range 4-38%) of patients with sarcoidosis and include joint involvement, bone lesions, and muscular disease. Approximately 25% of patients with sarcoidosis have associated arthropathy.  Pathology joints: joint involvement in sarcoido...
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Laminectomy

Laminectomy (whether unilateral or bilateral) refers to the surgical removal of the lamina of a vertebral body. By removing the lamina, we are able to decompress the spinal canal, and thus reduce the pressure on the spinal cord. Spinal stenosis may be caused by: arthritis of the spine (in olde...
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Le Fort fracture classification

Le Fort fractures are fractures of the midface, which collectively involve separation of all or a portion of the midface from the skull base. In order to be separated from the skull base, the pterygoid plates of the sphenoid bone need to be involved as these connect the midface to the sphenoid b...
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Pectus carinatum

Pectus carinatum, otherwise known as a pigeon chest, refers to a chest wall deformity in which the sternum protrudes anteriorly. It is less common than pectus excavatum. Clinical presentation Patients may present with dyspnoea and exercise intolerance. Pathology Associations scoliosis (comm...
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Pellegrini-Stieda lesion

Pellegrini-Stieda lesions are ossified post-traumatic lesions at (or near) the medial femoral collateral ligament adjacent to the margin of the medial femoral condyle. One presumed mechanism of injury is a Stieda fracture (avulsion injury of the medial collateral ligament at the medial femoral c...
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Tug lesion (musculoskeletal)

A tug lesion in musculoskeletal imaging is a term given to describe a bony traction reaction at a muscle attachment site likened to that of the "tug effect. They are benign and are placed as do not touch lesions. Notable sites include: distal femur: cortical desmoid posterior tibia: soleal li...
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Reactive arthritis

Reactive arthritis (ReA) is a sterile inflammatory arthritis that follows an infection at a different site, commonly enteric or urogenital. It is classified as a type of seronegative spondyloarthropathy. Terminology Reactive arthritis was formerly known as Reiter syndrome/disease, which is the...
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Calcium pyrophosphate dihydrate deposition disease

Calcium pyrophosphate dihydrate disease (CPPD disease), also referred as pyrophosphate arthropathy and perhaps confusingly as pseudogout, is common, especially in the elderly, and is characterised by the deposition of calcium pyrophosphate in soft tissues and cartilage. Terminology  CPPD is on...
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Seronegative spondyloarthritis

Seronegative spondyloarthritides, also known as spondyloarthropathies (SpA), are a group of musculoskeletal syndromes linked by common clinical features and common immunopathologic mechanisms. The subtypes of spondyloarthritis are usually distinguished on the basis of the patient’s history and c...
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Pneumorrhachis

Pneumorrhachis refers to a rare phenomenon characterised by the presence of gas within the spinal canal (either intra- or extradural). Clinical presentation Patients can often be asymptomatic 3. Pathology Aetiology Pneumorrhachis can result from a number of causes: trauma (traumatic pneumo...
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Posterior dislocation of the hip

Posterior dislocations of the hip, although uncommon, are the most common direction of dislocation for this joint, outnumbering anterior dislocations 9:1. Pathology It most frequently occurs in the setting of significant trauma, given the large amount of force required. The most common scenari...
Article

Thalassaemia

Thalassaemia is an autosomal recessive haemoglobinopathy that originated in the Mediterranean region. The genetic defect causes a reduction in the rate of globin chain synthesis which causes the formation of abnormal haemoglobin molecules. The resultant microcytic anaemia is the characteristic p...
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Genioglossus muscle

The genioglossus muscle is a fan-shaped extrinsic muscle of the tongue which makes up the bulk of the tongue. Summary origin: superior mental spine of the symphysis menti (posterior surface of midline mandible) insertion: entire tongue mass and body of the hyoid bone nerve supply: hypoglossa...
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Osteopoikilosis

Osteopoikilosis (OPK) is a sclerosing bony dysplasia characterised by multiple benign enostoses. It is a rare inherited benign condition incidentally found on skeletal x-rays. Its importance is predominantly in correct diagnosis so that it is not mistaken for pathology. Epidemiology The bone i...
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Skeletal "do not touch" lesions

Skeletal “don’t touch” lesions (also called leave me alone lesions) are so radiographically characteristic lesions that an additional diagnostic tests such as a biopsy are unnecessary and can be frankly misleading and lead to additional unnecessary surgery. Thus a radiologic diagnosis should be ...
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Chondrocalcinosis

Although frequently used as a synonym for calcium pyrophosphate dihydrate deposition disease (CPPD), chondrocalcinosis simply means visible calcification of both hyaline cartilage and fibrocartilage. Epidemiology It has a reported prevalence of 5-15% 2 and is thought to increase with age. Pat...
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Cozen fracture

Cozen fracture or phenomenon is the valgus angulation deformity of the tibia following a proximal tibial metaphyseal fracture in children. Epidemiology This typically occurs as a late deformity in children aged 3-6 years. Pathology Aetiology Proposed causes include: non-recognised or under...
Article

Glomangioma

Glomangiomas, also known as glomus tumours, are benign vascular tumours typically seen at the distal extremities. On imaging, they characteristically present as small hypervascular nodules under the finger nail.  Terminology These tumours should not be confused with paragangliomas, which are s...
Article

Exostosis

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: ivory exostosis exostosis of the external audit...
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Crossing sign (knee)

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...
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Haglund syndrome

Haglund syndrome refers to the triad (Haglund's triad) of: insertional Achilles tendinopathy retrocalcaneal bursitis Haglund deformity (i.e. posterosuperior calcaneal exostosis) This results in pain at the back of the heel. It is associated with calcaneal spurs, and the wearing of high heels...
Article

Benign notochordal cell tumour

Benign notochordal cell tumours (BNCT) are vertebral lesions that are usually asymptomatic and discovered incidentally on imaging of the head or spine. As this is a poorly-recognised entity, it can often be confused with aggressive vertebral lesions, such as a chordoma, when it is seen on imagin...
Article

Lateral centre-edge angle

The lateral centre-edge angle is a radiographic measurement of femoral head bony coverage by the acetabulum. It has primarily been described in assessing for acetabular dysplasia but can also be used in femoroacetabular impingement. It is calculated on AP pelvic radiographs by using drawing a b...
Article

Picture frame vertebral body

Picture frame vertebral body is a radiologic appearance in which the cortex of the vertebral body is thickened. This sign can be seen in patients with Paget disease.  It is a result of disorganised new cortical bone formation after excessive osteoclastic activity causes the resorption of normal...
Article

Metacarpal fracture

Metacarpal fractures are common. Fractures of the metacarpal bones account for 10% of all fractures and 40% of all hand fractures. The lifetime incidence of a metacarpal fracture is 2.5%. Terminology Specific names are given to fractures of the base of the first metacarpal (see: fractures of t...
Article

Syndactyly

Syndactyly refers to a congenital fusion of two or more digits. It may be confined to soft tissue (soft tissue syndactyly / simple syndactyly) or may involve bone (bony syndactyly / complex syndactyly). Epidemiology The overall estimated incidence is at ~1 per 2,500 to 5,000 live births 6,8. T...
Article

Coccydynia

Coccydynia refers to pain in and among the area of the coccyx. It is characterised by coccygeal pain which is typically provocated by pressure. It may remain unclear in origin owing to the unpredictability of the source of pain 1. Epidemiology No accurate data about the frequency of coccydynia...
Article

Polydactyly

Polydactyly (less commonly called hyperdactyly) refers to the situation where there are more than the usual number of digits (five) in a hand or foot. It can be broadly classified as: pre-axial polydactyly: extra digit(s) towards the thumb/hallux (radially) post-axial polydactyly: extra digit(...
Article

Post-axial polydactyly

Post-axial polydactyly refers to polydactyly where the additional digit is on the ulnar margin of the hand, or lateral to the 5th toe. Epidemiology Post-axial polydactyly is more common than pre-axial polydactyly, with an estimated incidence of 1 in 3000. Pathology Classification Post-axial...
Article

Extrusion index

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...
Article

Vertebral haemangioma

Vertebral haemangiomas are the most common benign vertebral neoplasms. They are usually asymptomatic and incidentally detected due to their characteristic features on imaging for other reasons. Please refer on the article on primary intraosseous haemangioma for a general discussion in this enti...
Article

Lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a rare multi-system disorder that can occur either sporadically or in association with the tuberous sclerosis complex (TSC) and is often considered a forme fruste of TSC.​ Epidemiology It almost exclusively affects women of childbearing age 7. The estimated in...
Article

Popliteal artery entrapment syndrome

Popliteal artery entrapment syndrome (PAES) refers to symptomatic compression or occlusion of the popliteal artery due to a developmentally abnormal positioning of the popliteal artery in relation to its surrounding structures such as with the medial head of gastrocnemius (MHG) or less commonly ...
Article

Femoroacetabular impingement

Femoroacetabular impingement (FAI) refers to a clinical syndrome of painful, limited hip motion resulting from certain types of underlying morphological abnormalities in the femoral head/neck region and/or surrounding acetabulum. FAI can lead to early degenerative disease. Epidemiology Pincer ...
Article

Multilayered periosteal reaction

Multilayered periosteal reaction, also known as a lamellated or onion skin periosteal reaction, demonstrates multiple concentric parallel layers of new bone adjacent to the cortex, reminiscent of the layers on an onion. The layers are thought to be the result of periods of variable growth 2. Pa...
Article

Codman triangle periosteal reaction

Codman triangle is a type of periosteal reaction seen with aggressive bone lesions. With aggressive lesions, the periosteum does not have time to ossify with shells of new bone (e.g. as seen in single layer and multilayered periosteal reaction), so only the edge of the raised periosteum will oss...

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