Turner syndrome, also referred as 45X, is the most common of sex chromosome abnormalities in females.
The incidence is estimated at 1:2000-5000 of live births, although the in utero rate is much higher (1-2% of conceptions) due to a significant proportion of fetuses with 45X abor...
The twelfth rib is an atypical rib. It is the shortest rib, and one of two floating ribs.
The 12th rib has a single facet on its head for articulation with the T12 vertebra. It has a short neck and no tubercle. It also lacks a costal groove and angle. internal surface ...
The two-slice-touch rule is a sign on MRI of the knee used to increase the sensitivity of diagnosing meniscal tears.
This rule states a meniscal tear is present if abnormal findings are present on two or more images - these do not have to be contiguous, e.g. can occur on sagittal and coronal sl...
The tympanic part of the temporal bone is situated inferiorly to the squamous part and anteriorly to the mastoid part.
The tympanic part surrounds the external auditory meatus, forming the anterior wall, floor and some of the posterior wall of the bony external acoustic meatus. The lateral bord...
Type 1 pelvic resections are complex surgeries that involve removing part of the pelvis, usually to resect malignant tumour.
Type 1 pelvic resections remove a varying amount of the iliac bone, and are classified in general terms as "partial" or "complete", depending on how much of the iliac bon...
Type II collagenopathies are a group of conditions collectively characterised by abnormalities in synthesis of collagen type II. This usually occurs due to a mutation in the COL2A1 gene.
Entities that fall under this group include:
achondrogenesis type II
platyspondylic lethal skeletal dyspla...
Of the seven cervical vertebrae, C3 through C6 have typical anatomy, while C7 looks very similar. C1 (atlas) and C2 (axis) have very distinct anatomical features. For a basic anatomic description of the structure a generic vertebra, see vertebrae.
small, oval-sized vertebral bodi...
Typical ribs are those numbered 2 to 10 with ribs 1, 11 and 12 considered atypical.
A typical rib is long and flat. They contain a:
Ribs have a rounded, smooth superior border. The inferior border is thin and sharp.
The ulna (plural: ulnae) is one of the two long bones of the forearm. It is located medially in the supinated anatomic position. It has a larger proximal end and tapers to a smaller distal end (opposite to the radius).
Prominent features of the ulna include:
The ulnar artery is a terminal branch of the brachial artery, arising at the proximal aspect of the forearm. Along with the radial artery, it is one of the main arteries of the forearm.
origin: terminal branch of the brachial artery
location: inferior aspect of the cubital fossa
Ulnar dimelia or mirror hand syndrome is a rare congenital anomaly of the upper limb characterized by absence of the radial ray (including thumb), duplication of the ulna and duplication of the ulnar halves of the carpals, metacarpals and phalanges 1.
The embryology of mi...
Ulnar impaction syndrome, also known as ulnar abutment or ulnocarpal loading, is a degenerative wrist condition caused by the ulnar head impacting upon the ulnar-sided carpus with the injury to the triangular fibrocartilage complex (TFCC).
Ulnar impaction syndrome most commonly pr...
Ulnar impingement syndrome is a wrist condition caused by a shortened distal ulna impinging on the distal radius proximal to the sigmoid notch. The syndrome is distinct from ulnar impaction syndrome, which typically occurs due to a long ulna (positive ulnar variance) impacting upon the triangula...
The ulnar nerve is one of the terminal branches of the brachial plexus and has motor and sensory supply to the forearm and hand.
The ulnar nerve originates as a terminal branch of the medial cord of the brachial plexus with nerve root fibres from C8-T1.
Ulnar nerve dislocation is an uncommon cause of pain and paresthesias in the ulnar nerve distribution. It occurs if the ulnar nerve subluxates and then dislocates over the anterior aspect of the medial epicondyle during flexion and extension of the elbow.
Ulnar nerve dislocation occ...
Ulnar styloid fractures occur in association with ~60% of distal radius fractures. Most of these are small avulsion fractures involving the tip of the ulnar styloid.
Usually these kind of fractures occur as the result of a fall on an outstretched arm and are often associated with a d...
Ulnar styloid impaction syndrome refers to wrist pain due to a long ulnar styloid process impacting upon the triquetral bone.
An unlar styloid >6mm in length is commonly regarded as being long. Impaction results in chondromalacia of the opposing articular surfaces, i.e. the proximal ...
Ulnar variance (also known as Hulten variance) refers to the relative lengths of the distal articular surfaces of the radius and ulna.
Ulnar variance may be:
neutral (both the ulnar and radial articular surfaces at the same level)
positive (ulna projects more distally)
negative (ulna projec...
There are several distinct ulnar-sided wrist impaction and impingement syndromes. Underlying anatomical causes exist for each syndrome, however, repetitive or excessive use of the forearm and wrist can also contribute.
ulnar impaction syndrome: positive ulnar variance
ulnar impingement syndrom...
The ulnomeniscal homologue (UMH) is an obliquely oriented, fibrocartilaginous structure, that forms part of the ulnar collateral ligament complex (ULC).
The UMH is located between the ulnar styloid process and the triquetrum. It adheres to the ulnar joint capsule and merges with ...
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 ...
Ultrasound of the elbow allows high-resolution imaging of elbow anatomy while simultaneously allowing dynamic evaluation of the joint, tendons, and ligaments.
There are multiple possible approaches to imaging the elbow with ultrasound. A typical protocol is as follows 1:
There are several approaches to ultrasound examination of the adult hip.
supine with the hip in mild external rotation
sagittal oblique plane parallel to the long axis of the femoral neck to assess femoral head and neck and for any joint effusio...
Ultrasound of the knee allows high-resolution imaging of superficial knee anatomy while simultaneously allowing dynamic evaluation of some of the tendons and ligaments. Knee ultrasound is somewhat limited compared with ultrasound examinations of other joints because the cruciate ligaments and th...
Ultrasound of the shoulder is a fast, relatively cheap and dynamic way to examine the rotator cuff and is particularity useful in diagnosing:
rotator cuff disorders
The examination requires attention to technique and appropriate patient positioning. ...
Ultrasound is a useful imaging modality for evaluation of the wrist, allowing high-resolution imaging of anatomy while simultaneously allowing dynamic evaluation of the joint, tendons, and ligaments.
There are multiple possible approaches to imaging the wrist with ultrasound. The exam...
Umbilical hernias are the most common ventral hernia and occur in the midline.
Ten times more common in females 2 and represent ~5% of all abdominal hernias 4.
Umbilical hernias present in the midline as painless or painful mass.
Uncovertebral joints, also called Luschka’s joints, are seen bilaterally between adjacent cervical vertebrae, identified by the cat ear shaped uncinate processes of the C3-7 vertebrae (C1 and C2 have no uncinate processes).
The articulation forms between the uncina...
Undifferentiated spondyloarthritis (uSpA), also known as undifferentiated arthritis, is a non-specific mono- or polyarthropathy that lacks the clinical, serological and radiological features that would allow specific diagnosis. It often turns out to be an early presentation of a more well known ...
Unfused spinous process, which is really failure of fusion of the neural arch, is a relatively common anatomical variant and is part of the spectrum of spina bifida occulta.
This should be differentiated from accessory ossicles of the spinous process, which appear after non-fusion of the secon...
Unicameral bone cysts (UBC), also known as simple bone cysts, are common benign non-neoplastic lucent bony lesions that are seen mainly in childhood and typically remain asymptomatic. They account for the S (simple bone cyst) in FEGNOMASHIC, the commonly used mnemonic for lytic bone lesions.
Unilateral facet dislocation is a relatively stable type of facet dislocation.
Flexion/distraction associated with rotation. The inferior articular facet of vertebral above moves over the superior facet of the vertebral below and becomes locked. It usually affects C4-C5 or...
Upper extremity dislocations are relatively common on account of the great range of motion the upper limb is capable of (a general principle is that the greater the range of motion of a joint, the more prone it is to dislocation). In many instances dislocations are associated with fractures eith...
The upper limb sustains a wide variety of fractures that range significantly in demographics, treatment and functional impact.
blade of scapula fracture
coracoid process fracture
Upper limb anatomy encompasses the anatomy of the shoulder, arm, elbow, forearm, wrist and hand.
Upper limb radiography is the radiological investigation of the shoulder girdle, humerus, ulna, radius, carpals and metacarpals of the hand. It is often utilised in the context of trauma to rule out fractures and dislocations.
The upper subscapular nerve, also known as the short or superior subscapular nerve, arises from the posterior cord of the brachial plexus and supplies the subscapularis muscle.
The upper subscapular nerve branches from the posterior cord of the brachial plexus with fibres...
Vacuum phenomenon in the shoulder refers to the presence of intra-articular gas in the shoulder joint. It is a very common occurrence, particularly in external rotation. This can cause circular or linear areas of low signal intensity on GRE MR images of the shoulder obtained with external rotati...
The terms valgus and varus refer to angulation (or bowing) within the shaft of a bone or at a joint.
It is determined by the distal part being more medial or lateral than it should be. Whenever the distal part is more lateral, it is called valgus. Whenever the distal part is more medial, it is ...
Van Buchem disease (VBD) is an extremely rare hereditary sclerosing bone dysplasia, also known as hyperostosis corticalis generalisata. This disease is characterised most notably by mandibular enlargement and thickening of the skull.
Less than 30 cases have been reported in the li...
The Vancouver classification of periprosthetic hip fractures proposed by Duncan and Masri is the most widely used classification system. It takes into account the fracture site, the status of the femoral implant, and the quality of surrounding femoral bone stock.
type A: fractures involve the t...
The vastus intermedius muscle is one of the 4 quadriceps muscles in the anterior compartment of the thigh. The others are the vastus medialis, the vests laterals, and the rectus femoris.
origin: upper two thirds of the anterior and lateral surfaces of the femur
The vastus lateralis is largest of the four quadriceps muscles in the anterior compartment of the thigh. The others are the rectus femoris, the vastus intermedius, and the vastus medialis.
lateral part of intertrochanteric line
margin of greater trochanter
The vastus medialis muscle is one of the four quadriceps muscles in the anterior compartment of the thigh. The others are the rectus femoris, the vastus intermedius, and the vastus lateralis.
medial part of intertrochanteric line
medial lip of the linea ...
The vertebra (plural: vertebrae) is the fundamental segmental unit of the vertebral column (also know as the spine).
Vertebrae, apart from those that are atypical, have a similar basic structure which can be described as an anterior vertebral body and a posterior neural (or verte...
Vertebra plana or pancake vertebra is the term given when a vertebral body has lost almost its entire height anteriorly and posteriorly, representing a very advanced crush fracture. It can occur with a variety of settings, including:
Langerhans cell histiocytosis (LCH)
Mnemonics to remember the causes of vertebra plana include:
E: eosinophilic granuloma
T: trauma; tuberculosis
F: fracture (trauma)
E: eosinophilic granuloma
T: tumour (e.g. metastases, myelo...
C7, also called vertebra prominens, is the seventh cervical vertebra and looks like vertebrae C3-C6, but has some distinct features making it an atypical vertebrae. The name vertebra prominens arises from its long spinous process, which is easily palpable.
C7 possesses the stand...
The vertebral column is affected by a range of anatomical variants of the body and/or neural arch as well as accessory ossicles. Knowledge of basic vertebral anatomy and ossification is essential for describing and understanding the range of anomalies.
The differential diagnosis for a vertebral body mass is broad and may range from a completely benign, sclerotic enostosis (bone island) to a malignant primary bone tumour.
Broadly, these lesions can be separated into:
primary bone tumours
Vertebral body squaring refers to the loss of normal concavity of the anterior border. It is seen in a variety of conditions including:
Ankylosing spondylitis is the most common cause of vertebral body squaring. It usually involves multiple level...
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...
Differential diagnosis of vertebral lesions includes:
Lesion originating in vertebral body
vertebral body osteomyelitis
giant cell tumour
Langerhans cell histiocytosis
Vertebral metastases represent the secondary involvement of the vertebral spine by haematogenously-disseminated metastatic cells. They must be included in any differential diagnosis of a bone lesion in a patient older 40 years.
This article will focus only on the metastasis involving the bony s...
Vertebral pneumatocysts refer to the presence of air filled cavity within the vertebrae, more prevalent on the cervical spine. Intraosseous pneumatocysts are more common adjacent to the sacroiliac joint while it is rare in the vertebral column. Other causes of vertebral air e.g. Kummel disease, ...
Vertebral scalloping is a concavity to the posterior (or less commonly anterior) aspect of the vertebral body when viewed in a lateral projection. A small amount of concavity is normal, as is concavity of the anterior vertebral body (see vertebral body squaring).
Vertebral vascular foramina are normal findings seen on cross sectional imaging and should not be mistaken for a fracture, especially in the setting of trauma.
basivertebral veins (forms Hahn's canal): foramen seen on the posterior surface of vertebral body in midline
Vertebroplasty is an imaging-guided procedure which entails percutaneous injection of surgical polymethylmethacrylate (PMMA) cement into a diseased vertebral body. Vertebroplasty provides pain relief and strengthening of the bone of vertebrae weakened by disease.
It can be used as ...
Very bizarre generalised lesions of bone tend to make you exclaim "Oh my! What is going here?" Although there are numerous potential causes, in this situation it is worth thinking of a number of entities:
skeletal dysplasias and metabolic diseases
Vickers ligament is a ligamentous structure connecting the lunate bone and TFCC to the distal radius and is seen in the vast majority of patients with Madelung deformity 1.
Release of this thickened ligament may help in improving symptoms associated with Madelung deformity 2.
Vitamin A (the retinoids) are a group of fat soluble vitamins required for many physiological functions, mainly vision, reproduction and epithelial maintenance. In the retina, a specific retinoid 11-cis-retinal is formed by photo-isomerisation within the rods and cones.
Vitamin C (ascorbic acid) is a water soluble vitamin that is a coenzyme for the formation of the structure protein collagen, particularly creating cross-linking of collagen fibres which greatly increases its tensile strength. It also acts as an antioxidant.
Vitamin D is used to describe a group of five fat-soluble secosteroid vitamins required for the homeostasis of serum calcium and phosphorus. Vitamin D is a prohormone that exists in two forms in humans (D2 and D3).
Cholecalciferol (D3) acts by regulating calcium and phosphorus intestinal absorp...
Volar intercalated segmental instability (VISI) is a type of instability involving the wrist. It is less often encountered than dorsal intercalated segmental instability (DISI).
It presents in most cases with nonspecific wrist pain and a "clunking" on the ulnar deviation ...
Volar plate avulsion injuries are a type of avulsion injury. The volar plate of the proximal interphalangeal (PIP) joint is vulnerable hyperextension injury as either an ligamentous or intra-articular fracture.
The volar plate forms the floor of PIP joint separating the joint spa...
Wackenheims line (also known as the clivus canal line or basilar line) is formed by drawing a line along the clivus and extending it inferiorly to the upper cervical canal.
Normally the tip of the dens is ventral and tangential to this line. In basilar invagination odontoid process transects th...
A Wagstaffe-Le Forte fracture refers to an avulsion fracture of the medial aspect of the distal fibula due to avulsion of the anterior talofibular ligament attachment.
lower extremity fractures
Waldenström sign is the increased distance between the pelvic tear drop and the femoral head. It is a non-specific sign of hip joint effusion.
>11 mm total distance or >2 mm difference compared to contralateral hip 1, 2
measured between the lateral aspect of ...
Ward triangle refers to a radiolucent area between principle compressive, secondary compressive and primary tensile trabeculae in the neck of femur.
It should be differentiated from Babcock triangle.
Wartenberg syndrome also known as cheiralgia paresthetica is due to compression of superficial branch of the radial nerve in the distal forearm. It can be secondary to tight watch band or handcuffs, compression from distal radius fracture or idiopathic.
Patients present ...
The wasp-waist sign is a radiographic appearance seen in patients with Klippel Feil syndrome. It results from fusion of the vertebral bodies such that the anteroposterior diameter at the level of the affected discovertebral joint is smaller than the diameter at the superior and inferior limits o...
The Weber ankle fracture classification (sometimes Danis-Weber) is a simple system for classification of lateral malleolar fractures, relating to the level of the fracture in relation to the ankle joint. It has a role in determining treatment.
below the level of the tal...
Wedge fractures are hyperflexion injuries to the vertebral body resulting from axial loading. Most commonly affecting the anterior aspect, wedge fractures are considered a single-column (i.e. stable) fracture.
Less commonly wedge fractures refer to a subtype of tibial plateau fractures. This a...
Reporting a weightbearing foot series can be a daunting process if you are inexperienced and often results in the films being left for somebody else to report. This article attempts to demystify the whole process by providing a structured approach to their reporting.
Werner syndrome is a progeroid rare autosomal recessive condition attributed to chromosome 8. It should not to be confused with similarly sounding Wermer syndrome.
Werner syndrome is characterised by
scleroderma-like skin changes such ...
Wiberg classification is a system used to describe the shape of the patella based mainly on the asymmetry between the patellar medial and lateral facets on axial views of the patella. Increasing number type indicates a larger degree of asymmetry.
Wiberg type 1 or a
A widened intercondylar notch on knee radiographs is a sign associated with:
haemophilic arthropathy (most commonly bilateral)
juvenile rheumatoid arthritis (most commonly bilateral)
tuberculosis arthropathy (usually unilateral) (3)
Widening of diploic space refers to diffuse, most commonly bilateral, calvarium widening secondary to extramedullary hematopoiesis within the skull.
Most commonly caused by systemic underlying pathologies such as:
chronic haemolytic disorders: may be associated with vertical striations...
The interpedicular (IP) distance which is the distance measured between the pedicles on frontal / coronal imaging can be widened in a number of situations.
conditions that can cause dural ectasia (can potentially cause widening)
Wilson disease, also known as hepatolenticular degeneration, is a rare autosomal recessive disorder of copper metabolism affecting multiple systems.
Wilson disease is commonly found in Japan. It affects 1 in 30,000-40,000 individuals 12.
Wilson disease, also known as hepatolenticular degeneration, is a multisystem disease, which rarely has musculoskeletal manifestations when there is accumulation of copper in the articular cartilage.
Reported manifestations include 1,2,3
Wimberger ring sign refers to a circular calcification surrounding the osteoporotic epiphyseal center of ossification in scurvy, which may result from bleeding.
It must not be confused with Wimberger sign, pathognomonic of congenital syphilis.
The Wimberger sign, also called Wimberger corner sign, refers to localised bilateral metaphyseal destruction of the medial proximal tibias. It is a pathognomonic sign for congenital syphilis.
It must not be confused with Wimberger ring sign seen in scurvy, which is sometimes also referred to as...
Wind-swept pelvis fracture is a combination a unilateral AP compression (open book) injury with a contralateral lateral compression injury.
It occurs when the internal rotation of one iliac wing causes a unilateral sacral compression fracture, while the same forces cause external rotation of t...
The (absent) pedicle sign, also called the winking owl sign, occurs on plain film when a pedicle is absent.
The term, winking owl sign, where the missing pedicle corresponds to the closed eye, the contralateral pedicle to the other open eye, and the spinous process to the beak of the animal on ...
The Winquist classification of femoral shaft fractures is based on fracture comminution and was proposed by Winquist in 1980. This classification is used with regards to management decision making, in determining whether a fracture requires an intramedullary nail or open reduction.
Type 0: no ...
Wormian bones are a subset of the small intrasutural bones that lie between the cranial sutures formed by the bones of the skull vault. The title Wormian bones is reserved for abnormal intrasutural bones that are typically found around the lambdoid suture.
Some consider them abnormal only if gr...
A mnemonic to remember ten of the numerous conditions associated with Wormian bones is:
P - pyknodysostosis
O - osteogenesis imperfecta
R - rickets
K - kinky hair syndrome
C - cleidocranial dysostosis
H - hypothyroidism/hypophosphatasia
O - otopalatodigital syndrome
Wrisberg rips are longitudinal vertical meniscal tears. They occur at the at the junction of the ligament of Wrisberg and the posterior horn of the lateral meniscus, and are commonly associated with anterior cruciate ligament tears 1.
The carpal tunnel view is an axial projection to demonstrate the medial and lateral prominences and the concavity. It can be utilised to investigate potential hook of hamate, pisiform and trapezium factures.
patient stands with the back facing the table
palmar surface of hand...
The clenched fist view is an additional projection used to evaluate suspected widening of the scapholunate interval, often performed bilaterally it is a functional view that requires the patient to clench both hands.
patient is seated in front of the table
both hands are pl...
The horizontal beam lateral wrist view is a modified lateral projection when performing the three view series of the wrist and carpal bones in trauma. It is the orthogonal projection of the PA wrist without any patient movement, making it the most appropriate projection for patients in pain.
The lateral wrist view is part of a three view series of the wrist and carpal bones. It is the orthogonal projection of the PA wrist.
patient is seated alongside the table
the affected arm if possible is flexed at 90° so the arm and wrist can rest on the table
abduct the hum...