≤11 ribs is associated with a number of congenital abnormalities and skeletal dysplasias, including:
Down syndrome (trisomy 21)
asphyxiating thoracic dysplasia (Jeune syndrome)
short rib polydactyly syndromes
chromosome 1q21.1 deletion...
Abdominal hernias (herniae also used) may be congenital or acquired and come with varying eponyms. They are distinguished primarily based on location and content. 75-80% of all hernias are inguinal.
Content of the hernia is variable, and may include:
small bowel loops
mobile colon segments (s...
Abscesses are focal confined collections of suppurative inflammatory material and can be thought of as having three components 1:
a central core consisting of necrotic inflammatory cells and local tissue
peripheral halo of viable neutrophils
surrounded by a 'capsule' with dilated blood vessel...
Achilles tendon thickening can occur for a number of reasons.
The Achilles tendon has an average AP diameter of 6 mm 1. Thickening of the tendon is when it exceeds 8 mm in AP diameter and can result from:
Alternating radiolucent and radiodense metaphyseal lines can be seen with a number of conditions and the differential diagnosis is wide:
growth arrest lines
rickets: especially those on prolonged treatment, e.g. vitamin D dependent rickets
Angiosarcoma of bone is a malignant vascular tumor of bone. These are rare and account for less than 1% of malignant bone tumors. The majority of these tumors arising in bone are primary; however, a tiny percentage are either radiation-induced or associated with bone infarction
There are several ankle impingement syndromes. They are characterized by limited range of motion and pain on attempting specific movements about the joint and often in a load-bearing position. They have variable etiology and pathogenesis. They are best classified according to location.
The key ...
Anterior knee pain is common with a variety of causes which can be divided anatomically using a layered approach1 from superficial to deep:
Superficial soft tissues
quadriceps tendinosis / partial tear
Aseptic loosening is considered relatively common complication of hip joint replacements. It is usually considered a long-term complication and is often considered as the most common complication 3.
Aseptic loosening can occur as a result of inadequate initial fixation, mechanical lo...
Athletic pubalgia refers to pain around the pubic symphysis and can have different causes, including what has become known as sports hernia or sportman's hernia and osteitis pubis.
Athletic pubalgia is a clinical syndrome of chronic lower pelvic and groin pain, usually encountered in athletes. ...
Atraumatic fractures, as the name suggests, occur with no trauma or minimal trauma that would not normally be expected to result in a fracture 1. They can be:
atypical fractures, e.g. bisphosphonate-related proximal femoral fractures
Avulsion fractures of the knee are numerous due to the many ligaments and tendons inserting around this joint. They include 1:
anterior cruciate ligament avulsion fracture
posterior cruciate ligament avulsion fracture
avulsion of the medial collateral ligament
origin of MCL avulsion fracture...
Barton fractures are fractures of the distal radius. It is also sometimes termed the dorsal type Barton fracture to distinguish it from the volar type or reverse Barton fracture.
Barton fractures extend through the dorsal aspect to the articular surface but not to the volar aspect. Therefore, i...
Benign lytic bone lesions encompass a wide variety of entities. A useful starting point is the FEGNOMASHIC mnemonic.
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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...
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...
Birth trauma relates to those conditions caused by both physical/mechanical and hypoxic injuries.
Birth trauma occurs in ~5 per 1000 births 2.
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...
Conditions associated with bone deformity from softening includes:
bowing of long bones
biconcave vertebral bodies / codfish vertebra
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 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 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...
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 indicativ...
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...
Bridging (or fusion) of the pubic symphysis can be associated with various systemic and local causes, including 1-3:
Buckle rib fractures are typical of an anterior compressive force to the chest, most commonly external cardiac massage, but can be seen following any such traumatic injury.
Buckle rib fractures occur in all ages, even very elderly patients. Thus ribs are not the same as most adult lo...
Butterfly fragments are large, triangular fracture fragments seen commonly in comminuted long bone fractures. The term is commonly used in orthopedic surgery, and results from two oblique fracture lines meeting to create a large triangular or wedge-shaped fragment located between the proximal an...
The capitolunate angle is the angle between the long axis of the capitate and the mid axis of the lunate on the sagittal imaging of the wrist. In a normal situation it should be less than 30o in the resting (neutral) position.
The angle is increased in carpal instability such as with a dorsal i...
Carpal angle is defined by two intersecting lines, one in contact with the proximal surface of the scaphoid and the lunate and the other line through proximal margins of the the triquetrum and the lunate. Its normal value is between 130° and 137°.
It is increased in (> 139°)
The differential for cartilagenous lesions includes:
There are several important causes of an abnormal lunate signal on MRI, the most frequent causes being Kienbock disease (25%), ulnar impaction syndrome (25%) and intraosseous ganglia (20%).1 Appreciation of the pattern of bone signal change can often allow the correct diagnosis to be made.
Cervical spine fractures can occur secondary to exaggerated flexion or extension, or because of direct trauma or axial loading.
The cervical spine is susceptible to injury because it is highly mobile with relatively small vertebral bodies and supports the head which is both heavy and...
Cervical spine injuries can involve the cervical vertebral column, intervertebral discs and cervical spine ligaments, and/or cervical spinal cord. The cervical spine accounts for ~50% of all spinal injuries.
5-10% of patients with blunt trauma have a cervical spine injury 1.
Chamberlain line is a line joining the back of hard palate with the opisthion on a lateral view of the craniocervical junction.
It helps to recognize basilar invagination which is said to be present if the tip of the dens is >3 mm above this line.
McGregor developed a modificatio...
Chance fractures, also referred to as seatbelt fractures, are flexion-distraction type injuries of the spine that extend to involve all three spinal columns. These are unstable injuries and have a high association with intra-abdominal injuries.
They tend to occur from a fl...
Chondrocalcinosis is a descriptive term indicating the presence of gross calcium deposition within articular cartilage, i.e. both hyaline and fibrocartilage.
Chondrocalcinosis articularis was an early term for calcium pyrophosphate dihydrate deposition disease (CPPD) 5, which may e...
There are many signs in radiology that are related to Christmas:
snowcap sign in avascular necrosis
in total anomalous pulmonary venous return
in pituitary macroadenomas
snowstorm appearance in complete hydatidiform and testicular microlithiasis
holly leaf sign in calcified pl...
Clavicle tumors may be malignant or benign.
osteoma: uncommon, sclerotic, hamartomatous surface lesion
enchondroma: rare, geographic, intramedu...
Closed reduction or manipulation is a common non-invasive method of treating mildly displaced fractures. Usually performed in an emergency department or orthopedic clinic with light sedation and analgesia, the fracture is manipulated back into anatomic alignment and immobilized with a cast, brac...
Coaptation refers to a joining or reuniting of two surfaces. This can be in the setting of ends of a broken bone or the edges of a wound or edges of a valve.
Codman triangle is a type of periosteal reaction seen with aggressive bone lesions. The periosteum does not have time to ossify with shells of new bone (e.g. as seen in a single layer and multilayered periosteal reaction) in aggressive lesions, so only the edge of the raised periosteum will ossi...
COL4A1-related disorders are a group of autosomal dominant disorders caused by a mutation in the COL4A1 gene.
The exact prevalence is unknown, but the group of disorders is considered to be under-recognized, especially asymptomatic variants 1.
The clinical ...
Companion shadows are smooth, homogeneous, radiopaque shadows running parallel along the bones. In a study of 700 chest radiographs, Ben Felson found that 75% had companion shadows on the lower ribs 3.
They appear secondary to soft tissues and intercostal muscles running ...
Complications of total hip arthroplasty are common and it is essential for the radiologist to be aware of them in the assessment of radiographs of total hip replacements. Complications are many and can occur at various time intervals following the initial surgery:
aseptic loosening: considered ...
There are many conditions that can involve both skin and bone.
osteolytic bone lesions
basal cell nevus syndrome
langerhans cell histiocytosis
Congenital limb amputation is the absence of a fetal limb or part of a limb that usually occurs due to disruption of vascular supply.
Congenital amputations occur in 0.5 (range 0.03-1) per 1000 live births 2.
They are slightly more common in the upper limb (60%) than ...
A contrecoup injury of the knee is a bone contusion of the posterior lip of the medial tibial plateau. It occurs during knee reduction after a pivot shift injury and is highly associated with ACL tears 1, and peripheral tear or meniscocapsular separation of the medial meniscus posterior horn 2.
Coronal vertebral clefts refer to the presence of radiolucent vertical defects on a lateral radiograph.
It is most often seen in premature male infants 1,3. As they can occur as part of normal variation (especially in the lower thoracic-upper lumbar spine of premature infants) t...
Fractures of the coronoid process of the ulna are uncommon and often occur in association with elbow dislocation.
Fracture of the coronoid process is thought to result from elbow hyperextension with either avulsion of the brachialis tendon insertion or shearing off by the...
Craniovertebral junction (CVJ) anomalies can be congenital, developmental or due to malformation secondary to any acquired disease process. These anomalies can lead to cranial nerve compression, vertebral artery compression and obstructive hydrocephalus.
The craniovertebral junction ...
Crystal arthropathies are a group of joint disorders due to deposition of crystals in and around joints which lead to joint destruction and soft tissue masses.
The most common arthropathies are:
gouty arthropathy due to monosodium urate (MSU) deposition
pseudogout due to calcium py...
The C sign is an important radiological sign which may be seen on a lateral radiograph of the ankle in those with the talocalcaneal subtype of tarsal coalition.
A continuous C-shaped arc on a lateral ankle radiograph is formed by the medial outline of the talar dome an...
The musculoskeletal manifestations of cystic fibrosis are uncommon compared to the well known respiratory manifestations.
Symptoms are non-specific and include joint pain, joint swelling, back pain, and myalgia. These may mimic rheumatic symptoms, however, they do not me...
There is broad differential for cyst-like lesions around the knee.
popliteal synovial cyst - Baker cyst
intra-articular ganglion cyst
ACL ganglion cyst
PCL ganglion cyst
Hoffa fat pad ganglion cyst
extra-articular ganglion cyst
A generalized retardation in skeletal maturation has different causative or etiological factors, these can be classified as follows:
chronic ill health
congenital heart disease (especially cyanotic)
chronic renal disease
inflammatory bowel disease
malnutrition: failure to thrive (FTT)
The differential diagnosis for a dense base of the skull includes:
Van Buchem disease
The differential diagnosis of dense metaphyseal bands is wide.
chronic anemia, e.g. sickle cell disease, thalassemia
chemotherapy, e.g. methotrexate
growth acceleration lines following growth arrest due to systemic illness or stress in infancy or childhood, e.g...
Diaphragmatic paralysis (also considered very similar to the term diaphragmatic palsy) can be unilateral or bilateral.
Clinical features are highly variable according to underlying etiological factor:
unilateral paralysis: asymptomatic in most of the patients as the othe...
Diaphyseal lesions are unsurprisingly predominantly found centered in the diaphysis.
simple bone cyst
myeloma / plasmacytoma
round cell tumor, e.g. Ewing sarcoma (children)
Forefoot pain in the metatarsal region is a common complaint and may be caused by a number of conditions. It is worthwhile for a radiologist to have knowledge of the potential causes and their imaging features 1.
plantar plate disruption
Diffuse bone sclerosis can result from a number of causes. They include:
sickle cell disease
diffuse osteosclerosing myeloma: rare
metabolic bone disorders
A diffuse homogeneous bone marrow FDG uptake usually reflects hyperplastic bone marrow which can be seen in the following conditions:
granulocyte colony stimulating factor (G-CSF)
Diffuse T1 vertebral bone marrow signal loss has a number of causes. T1-weighted imaging without fat suppression is one of the most important sequences for distinguishing between normal and abnormal bone marrow. Given the homogeneity, this appearance can often be difficult to spot as abnormal. ...
The term disarticulation refers to the disconnection of all or part of a limb from the body, specifically through a joint. This is in contrast to amputation, which is the disconnection or removal of the structure through a bone.
Disorganized or complex periosteal reaction has spicules with random orientation and appearance. It can be seen in highly aggressive processes:
malignant fibrous histiocytoma
spindle cell sarcoma
Erosion or absence of the distal ends of the clavicles may be seen in a wide range of conditions.
weightlifter's shoulder: due to repetitive microtrauma; classically described in weightlifters, but can affect anyone performing repetitive overhead lift...
Dynamic hip screws (DHS) are a femoral head-sparing orthopedic 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-pr...
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...
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.
Empyemas are purulent inflammatory collections within a body cavity. Contrast this with abscesses, which arise within parenchymal tissue, rather than occupying a pre-existing anatomical space.
Colloquially, the standalone term empyema is used to refer to thoracic empyemas but there...
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...
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...
Epigastric hernias, also known as fatty hernias of the linea alba, occur ventrally through a defect in the linea alba superior the umbilicus.
Shows a midline defect which is usually small with or without herniation...
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...
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
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...
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
Ewing sarcoma family of tumors are a group of small round blue cell tumors that are closely histogenetically related, all demonstrating non-random t(11;22)(q24;q12) chromosome rearrangement resulting in the formation of the EWS-ETS fusion gene 1-3.
Although the literature is litte...
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)
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
Knowing extraskeletal musculoskeletal lesions by compartment is useful to help generate a meaningful differential diagnosis:
extraskeletal myxoid chondrosarcoma
Facet dislocation refers to anterior displacement of one vertebral body on another. Without a fracture, the only way anterior displacement can occur is by dislocation of the facets.
Facet dislocation can occur to varying degrees:
The injury usua...
Fall onto an outstretched hand (FOOSH) is a common mechanism for wrist-forearm fractures, in certain cases with involvement of elbow structures, particularly in children.
Some injuries that result from such a fall include:
Femoral anteversion refers to the orientation of the femoral neck in relation to the femoral condyles at the level of the knee. In most cases, the femoral neck is oriented anteriorly as compared to the femoral condyles. In the case of posterior orientation, the term femoral retroversion is also ...
Fetal rib fractures can be caused by certain skeletal dysplasias. These include:
osteogenesis imperfecta: type II - one of the classical causes of fetal rib fractures
achondrogenesis: type Ia - Houston-Harris sub type
Fibromatosis refers to a wide range of soft tissue lesions that share an underlying histopathologic pattern of fibrous tissue proliferation. They can occur in a variety of anatomic sites (e.g. musculoskeletal, abdominopelvic, breast, etc.) and also vary in their behavior, ranging from indolent/b...
Fibrous hamartoma of infancy is a rare benign tumor of the subcutaneous tissues seen in children. More than 90% of cases present in the first year of life with up to 25% being congenital 1.
There is a reported male:female ratio of 2:1 but the exact incidence is unknown 2.
The differential for fibrous lesions is wide and includes:
osteofibrous dysplasia / adamantinoma
malignant fibrous histiocytoma / fibrosarcoma
Floating meniscus (also known as meniscal avulsion) occurs in acute traumatic settings when the meniscotibial coronary ligaments get disrupted leading to avulsion of the meniscus from the tibial plateau.
Displacement of the meniscus for 5 mm or more from the tibial p...