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...
Achondrogenesis type Ia, also known as the Houston-Harris subtype, is a subtype of achondrogenesis. It is an extremely rare lethal skeletal dysplasia (chondrodysplasia) with a characteristic severe disarrangement of endochondral ossification.
The growth plate cartilage completely la...
This classification was proposed by Ahlback et al. in 1968.
According to Ahlbäck system, knee joint osteoarthritis is classified as:
grade 1: joint space narrowing (less than 3 mm)
grade 2: joint space obliteration
grade 3: minor bone attrition (0-5 mm)
grade 4: moderate bone attrition (5-1...
Allen and Ferguson classification is used for research purposes to classify subaxial spine injuries. It is based ofn the mechanism of injury and position of the neck during injury. This classification was proposed by Allen and Ferguson in 19823 and at the time of writing (July 2016) remains the ...
The American Academy of Orthopedic Surgeons classification of periprosthetic hip fractures divides the femur into three separate regions:
level I: proximal femur distally to the lower extent of the lesser trochanter
level II: 10 cm of femur distal to level I
level III: femur distal to level...
The Anderson and D'Alonzo classification is the most commonly used classification of fractures of the odontoid process of C2.
fracture of the upper part of the odontoid peg
above the level of the transverse band of the cruciform ligament
usually considered stable...
Ankle fractures account for ~10% of fractures encountered in trauma, preceded only in incidence by proximal femoral fractures in the lower limb. They have a bimodal presentation, involving young males and older females. Ankle injuries play a major part in post multitrauma functional impairment t...
Anterior cruciate ligament (ACL) avulsion fractures or tibial eminence avulsion fractures are a type of avulsion fracture of the knee. This typically involves separation of the tibial attachment of the ACL to variable degrees. Separation at the femoral attachment is rare 5.
It is ...
The AO classification of proximal humeral fractures, along with the Neer classification, is one of the most frequently used systems for classifying proximal humeral fractures.
The AO classification divides proximal humeral fractures into three groups, A, B and C, each with subgroups, and place...
Arnold-Hilgartner classification is a plain radiograph grading system for haemophilic arthropathy of the knee 1,2:
stage 0: normal joint
stage I: no skeletal abnormalities, soft-tissue swelling is present
stage II: osteoporosis and overgrowth of the epiphysis, no cysts, no narrowing of the ca...
The American Spinal Injury Association (ASIA) was developed by the American Spinal Injury Association in 2006, and at the time of writing (July 2016), remains the most widely used scale.
This scale is part of the ASIA spinal cord injury classification. It divides spinal cord injuries into 5 cat...
The Bado classification is one of the more widely used classifications for Monteggia fracture-dislocations and mainly focuses on the radial component. Four types are recognised and are generally based on the principle that the direction in which the apex of the ulnar fracture points is the same ...
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
There are a bewildering number of bone tumours with a wide variety of radiological appearances:
bone island / enostosis
Brachydactyly type A1 or Farabee type brachydactyly is a subtype of brachydactyly. It was the first human anomaly recognised to have a mendelian pattern of inheritance. The anomaly is characterised by hypoplasia or aplasia of middle phalanges of the second to fifth digits in hands and feet and p...
Brachydactyly type A2 or Mohr-Wriedt type is characterised by hypoplasia/aplasia of the second middle phalanx of the index finger, second toe and sometimes little finger. There is radial deviation of the index finger and tibial deviation of the second toe.
Type A2 brachydactyly can b...
Brachydactyly type A3 is characterized by shortening of the middle phalanx of the little finger with radial deviation of distal phalanx. Slanting of the distal articular surface of the middle phalanx leads to radial deflection of the distal phalanx. However it is not always associated with clino...
Brachydactyly type A4 or Temtamy type is characterised by brachymesophalangy (absent or hypoplastic middle phalanx) of the second and fifth fingers. Other less common features include club foot, clinodactyly, ulnar deviation of the second finger.
Like other brachydactyly, type A4 is ...
Brachydactyly type A5 is characterized by absence of the middle phalanges and nail dysplasia with duplicated terminal phalanx of the thumb with resultant bifid thumb. Inheritance is suggested as autosomal dominant.
There is variation in the relationship between the glenoid labrum and the anterior shoulder joint capsule. This has been divided into three types:
Type 1: capsule inserts into the labrum proper
Type 2: capsule inserts into the base of the labrum, or within 1cm of the base
Type 3: capsule inse...
The Castellvi classification is used for lumbosacral transitional vertebra (LSTV):
type I: enlarged and dysplastic transverse (at least 19 mm)
type II: pseudoarticulation of the transverse process and sacrum with incomplete lumbarisation/sacralisation; enlargemen...
The Catterall classification is based on radiographic appearances of the epiphysis and metaphysis visible in osteonecrosis of the femoral head:
bone absorption changes visible in the anterior aspect of the epiphysis of femoral head
changes are visible best in frog leg lateral view
Cervical degenerative changes can be graded using a very old but reliable classification given by Kellgren et al. It is based on findings on a lateral cervical spine radiograph although it can also be applied to MRI evaluation of spine.
The key parameters are osteophyte formation, intervertebra...
There are several cervical spine fracture classification systems:
Anderson and D'Alonzo classification (odontoid fracture)
Roy-Camille classification (odontoid fracture)
Levine and Edwards classification (for traumatic injuries to axis)
Allen and Ferguson classification (subaxial spine injur...
Chondromalacia can be divided into 4 grades by MRI, typically using fat saturated proton density sequences. This grading system is the modified Outerbridge grading system, which was devised for arthroscopy initially for assessment of chondromalacia patella, but then modified and extended for all...
This classification of gamekeeper's thumb (also known as skier's thumb) was proposed by Hintermann et al. 1 in 1993 and is based on whether a fracture is present and whether the injury is stable:
fracture present, which is non-displaced and stable in flexion
typically treated with a sp...
Classification of proximal femoral deficiency (PFFD) can be complicated and numerous such classifications have been proposed. For a discussion of the condition refer to the article proximal focal femoral deficiency.
One of the simplest and most widely used is that proposed by Aitken 1 which is ...
There are several classification systems for sacral fractures, but the most commonly employed are the Denis classification and subclassification systems, and the Isler classification system. These classification systems are important to understand as proper classification can impact management.
Closed reduction-internal fixation, abbreviated to CRIF, refers to the orthopaedic operative management of a fracture (or fracture-dislocation complex) where closed reduction is performed (manipulation) and internal fixation is applied, usually in the form of K-wires to stabilise the fracture.
The Cooke and Newman classification of periprosthetic hip fractures is a modification of the Bethea classification proposed several years earlier.
explosion type fracture, comminuted around the stem of the implant
the prosthesis is always loose and the fracture is inherently unstable
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 th...
Dameron-Lawrence-Bofte classification of proximal fifth metatarsal fractures divides fractures into three zones based on anatomy:
zone 1: tuberosity of 5th metatarsal
avulsion fracture of tuberosity (pseudo-jones fracture)
zone 2: meta-diaphyseal junction
zone 3: proximal dia...
Degloving injuries can refer to a number of conditions:
degloving soft tissue injury
Morel-Lavallee lesion (closed degloving soft tissue injury)
intramuscular degloving injury
degloving bowel injury
Deltoid ligament injuries involve the deltoid ligament that forms the medial part of the ankle joint. It attaches the medial malleolus to multiple tarsal bones.
Mechanism of injury
It occurs due to eversion and/or pronation injury, or can be associated with lateral ankle fractures.
Distal fibula fractures are the most common type at the ankle and are usually the result of an inversion injury with or without rotation. They are the extension of a lateral collateral ligament injury.
Most ankle injuries occur because of an inversion injury. A pure...
This classification was proposed by Eaton and Malerich in 1980, and presently (time of writing, August 2016) along with Keifhaber-Stern classification, is the most widely accepted classification of volar plate avulsion injuries 1.
Knowledge of the orthopaedic Eaton classification is practical ...
The Ficat and Arlet classification uses a combination of plain radiographs, MRI, and clinical features to stage avascular necrosis of the femoral head.
plain radiograph: normal
clinical symptoms: nil
plain radiograph: normal or minor osteopenia
The Ficat classification of osteonecrosis is based on radiographic findings. In 1985 Dr Ficat published a modified version of his initial classification in 1980:
preclinical and preradiographic
diagnosis is suspected in one hip when the other has a definite disease - this is the stage...
General rules and nomenclature of fractures should be understood by, and familiar to, anyone involved in the interpretation or management of fractures of the extremities. This article covers basic nomenclature of fractures.
Before the most appropriate treatment for a fr...
The Frykman classification of distal radial fractures is based on the AP appearance and encompasses the eponymous entities of Colles fracture, Smith fracture, Barton fracture, chauffeur fracture. It assesses the pattern of fractures, involvement of the radioulnar joint and presence of a distal u...
The Garden classification of subcapital femoral neck fractures is the most widely used. It is simple and predicts the development of AVN 1,2. Garden described particular femoral neck and acetabular trabeculae patterns which can assist in recognising differences within this classification system...
The Gartland classification of supracondylar fractures of the humerus is based on the degree and direction of displacement, and the presence of intact cortex. It applies to extension supracondylar fractures rather than the rare flexion supracondylar fracture.
type I: undisplaced...
The Genant classification of vertebral fractures is based on the vertebral shape, with respect to vertebral height loss involving the anterior, posterior, and/or middle vertebral body.
grade 0: normal
grade 1: mild fracture, 20% to 25% loss of height
grade 2: moderate fracture, 25% to 40% los...
Gilula three carpal arcs refer to the alignment described on posteroanterior or anteroposterior wrist radiographs and are used to assess normal alignment of the carpus:
first arc: is a smooth curve outlining the proximal convexities of the scaphoid, lunate and triquetrum
second arc: traces the...
The Goutallier classification is a classification system used to quantify the amount of degeneration of the rotator cuff muscles, particularly in the context of rotator cuff tendon tears. Although originally described in shoulder CT 1, it is applicable and now most commonly used in MR. It is bas...
According to CT myelography, brachial plexus injuries can be classified into six types 1:
N type: normal root sleeve and nerve roots
A1 type: slightly deformed root sleeves and nerve roots as compared to unaffected site
A2 type: obliteration of the tip of root sleeves and deformed thickened n...
The Graf method for ultrasound classification system for developmental dysplasia of the hip (DDH) in infants, combines both alpha and beta angles. There are a number of additional subdivisions, which are often not used clinically.
As a general rule, the alpha angle determines the type and in s...
The Gustilo Anderson classification, sometimes referred to as the Gustilo classification is the most widely accepted classification system of open (or compound) fractures.
The grading system is used to guide management of compound fractures, with higher grade injuries associated with higher ris...
The Johansson classification of periprosthetic hip fractures was the first classification system proposed and is the simplest. It is based on the level of the fracture in relation to the prosthesis.
type I: fracture proximal to the tip of the prosthesis with the stem still in contact with the m...
The Judet and Letournel classification is the most widely used classification of acetabular fractures.
It is based on three radiographic views (anteroposterior view, obturator oblique view and Iliac oblique view) and classifies acetabular fractures into ten major fracture patterns, which cons...
This classification was proposed originally by Hastings and later modified by Keifhaber and Stern in 1998. This classification, along with the Eaton classification, is the most widely accepted classification at the time of writing (August 2016) for the management of volar plate avulsion injuries...
The Kellgren and Lawrence system is a method of classifying the severity of knee osteoarthritis (OA) using five grades. This classification was proposed by Kellgren et al. in 1957 2 and later accepted by WHO in 1961.
grade 0: no radiographic features of OA are present
grade 1: ...
The Kuwada classification of Achilles tendon tear was proposed in 1990 4 and at the time of writing (July 2016) remains the most widely used system for describing achilles tendon rupture.
Achilles tendon tears may be grouped (according to severity of the tear and degree of retr...
The Langer Saldino syndrome or achondrogenesis type II is a sub type of achondrogenesis. It is an extremely rare fatal skeletal dysplasia.
Majority of cases are sporadic. Autosomal dominant inheritance is also another mode. There is mutation in the collagen type II gene (CO...
Lateral humeral condyle fractures also referred to simply as lateral condyle fractures (in the appropriate context), are relatively common elbow fractures that predominantly occur in children. They may be subtle but are hugely important to diagnose in a timely manner because if they are missed, ...
The Lauge-Hansen classification system is used for the classification of the ankle injuries based on injury mechanisms which have predictable patterns and imaging findings. Along with the Weber classification, these systems are useful tools for describing and classifying ankle injuries.
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...
Levine and Edwards classification is used to classify hangman fractures of C2 (also known as traumatic spondylolisthesis of axis).
type I: fracture with <3 mm antero-posterior deviation
no angular deviation
type II: fracture with >3 mm antero-posterior deviation
Limbus fractures are not to be confused with a limbus vertebra. They can be classified as follows:
type I: avulsions of the posterior cortical vertebral rim
type II: central cortical and cancellous bone fractures
type III: lateralised chip fractures
type IV: span the entire length and breadt...
The Lodwick classification is a system for describing the margins of a lucent/lytic bone lesion. The terms used in the description suggest the level of concern for an aggressive, and possibly malignant, process.
type 1: geographic
1A: thin, sclerotic margin
1B: distinct, well-...
Several classification systems exist for the lunate morphology 1, 2.
The lunate classification proposed by Veigas et al. is arguably the most relevant 3:
type I lunates: single distal articular facet for the capitate
type II lunates: additional distal articular facet medially...
The Magerl classification of thoracolumbar spinal fractures is based on the three column concept by Denis, and the McAfee classification. It relies exclusively on CT findings.
A: compression injuries
A1: impaction fractures
A1.1: endplate impaction
A1.2: wedge impaction
Here is a list of some of the most useful differential diagnoses in musculoskeletal imaging.
lucent/lytic bone lesions (FEGNOMASHIC)
multiple lucent/lytic bone lesions
benign lytic bone lesions in patients under 30
diffuse bony sclerosis
permeative process in bone
The Mason classification is used to classify radial head fractures and is useful when assessing further treatment options 1-2.
type I: non-displaced radial head fractures (or small marginal fractures), also known as a "chisel" fracture
type II: partial articular fractures with displacement (>2...
Mayfield classification of carpal instability, also known as perilunate instability classification (carpal dislocations), describes carpal ligament injuries.
Instability has been divided into four stages 1-2:
stage I: scapholunate dissociation (rotatory subluxation of the scaphoid)
Mayo classification of scaphoid fractures divides them into three types according to the anatomic location of the fracture line:
Fractures of the distal third are further divided into distal articular surface and distal tubercle fractures:
McAfee classification of acute traumatic spinal injuries is based on the three column concept of the spine. CT is needed for accurate assessment.
wedge compression: isolated anterior column compression
stable burst: anterior and middle column compression but posterior column i...
Medial collateral ligament (MCL) injuries are graded into three groups on MRI, much in the same way as many other ligaments:
grade 1: (minor sprain) high signal is seen medial (superficial) to the ligament, which looks normal
grade 2: (severe sprain or partial tear) high signal is seen medial ...
The metaphyseal-diaphyseal angle (of Drennan) is an important measurement used to distinguish betweeen tibia vara (Blount disease) and physiological bowleg.
This angle is measured by drawing a line along the long axis of the tibia, creating a perpendicular to this line, and drawing another lin...
The Milch classification is one of the classificaiton systems that can be used for lateral humeral condyle fractures and splits these fractures into two groups depending on their relationship with the trochlear groove:
type I: fracture passes lateral to the trochlear groove
type II: fracture p...
Mitchell classification of avascular necrosis is based on MRI signal characteristics within the centre of the lesion on T1 and T2-weighted images.
The lesion is classified into four stages with stage A representing early disease and stage D representing late disease. However, th...
Disc degeneration can be graded on MRI T2 spin-echo weighted images using a grading system proposed by Pfirrmann 1. This classification is not used on routine spine reports, being more important for research purposes.
grade I: disc is homogeneous with bright hyperintense white signal intensity ...
MRI grading system for abnormal high meniscal signal intensity was reported by Lotysch et al. MR grades 1, 2 and 3 have been used:
grade 1: small focal area of hyperintensity, no extension to the articular surface
grade 2: linear areas of hyperintensity, no extension to the articular surface
The Neer classification of proximal humeral fractures is probably the most frequently used along with the AO classification of proximal humeral fractures. Even if an exact knowledge of this classification system is beyond the everyday use of many radiologists, the terminology and factors which i...
Nerve injury classification describes the various features of nerve injury on MRI with respect to pathological events.
grade I: there is increased T2/STIR signal in the nerve, however the muscle appears normal
grade II: increased T2/STIR signal in ne...
Bone marrow signal of the clivus changes predictably with age and is well assessed with midline T1 non-fat-saturated, non-contrast images. As is seen in the rest of the body the proportion of yellow (fatty) marrow increases with age. Knowledge of these changes allows diagnosis of the abnormal cl...
Occipital condylar fractures result from high-energy blunt trauma and is a specific and localized type of basilar skull fracture.
The exact incidence of these fractures is unknown but are reported to occur in 3-4% patients with moderate-severe traumatic brain injuries 3.
Odontoid process fracture, also known as the peg or dens fracture, occurs where there is a fracture through the odontoid process of C2.
The mechanism of injury is variable, and can occur both during flexion or extension with or without compression 5.
There are two cl...
Open book pelvic injuries are most often the result of high-energy trauma and are associated with significant morbidity and mortality due to associated vascular injuries.
Open book pelvic injuries result from an anteroposterior compression injury to the pelvis and result in a combin...
Orthoroentgenogram is a radiographic study used to evaluate anatomic leg length and calculate leg-length discrepancies. This study utilises a long ruler placed on the film, and three radiographs including bilateral hips, knees and ankles.
Similar studies used to evaluate true leg length include...
Osteochondral injury staging system for MRI attempts to grade the stability and severity of osteochondral injury and is used to plan management.
injury limited to articular cartilage
MRI findings: subchondral oedema
x-ray findings: none
cartilage injury with associated sub...
Osteochondritis dissecans can be classified at surgery into 4 stages:
lesion in continuity with the host bone
covered by intact cartilage
stable on probing
partial discontinuity of the lesion from the host bone
unstable on probing
fragment not dislocat...
The several forms of osteogenesis imperfecta (OI) have been classified, representing wide variation in appearance and severity, and clinical features vary widely not only between types but within types.
OI was initially classified by type according to a scheme developed by Dr Da...
Palmer classification for triangular fibrocartilage complex (TFCC) abnormalities is based on the cause, location and degree of injury 1:
Class 1 - traumatic injury
a: central perforation
b: ulnar avulsion with or without distal ulnar fracture
may involve the proximal or distal lamina (foveal...
Harrington criteria can be used to predict which skeletal metastases are at high risk of pathological fracture and should undergo prophylactic internal fixation. It preceded the Mirel classification for impending pathological fracture but has not been validated and its use is debated.
Mirel classification is a system used to predict the highest risk of pathological fracture among bones affected by metastases.
involving <1/3 of bone diameter
involving 1/3-2/3 of bone diameter
Several classification systems have been proposed for periprosthetic fractures of the hip:
American Academy of Orthopedic Surgeons (AAOS) classification
Cooke and Newman (modified Bethea) classification
Vancouver classification: most widely used
The peroneal tubercle/trochlea is one of the two bony projections or protuberances that may be seen on the lateral aspect of the calcaneus, the other one being the retrotrochlear eminence.
The peroneal tubercle is present immediately inferior to the fibular malleolus, lying in between the two t...
Piedmont fractures have been variably defined in the literature. Many suggest that Piedmont fractures are synonymous with Galeazzi fractures. That is a fracture of the radius at the middle and distal third with associated disruption of the distal radioulnar joint.
The initial report about the s...
Pipkin classification is the most commonly used classification for femoral head fractures, which are uncommon but are associated with hip dislocations.
type I: fracture distal to the fovea capitis, a small fracture not involving the weightbearing surface
type II: fracture proxi...
RASopathies are a class of developmental disorders caused by germline mutations in genes that encode for components or regulators of the Ras/mitogen activated protein kinase (MAPK) pathway.
As a group, RASopathies represent one of the most common malformation syndromes, with an in...
The term retrolisthesis refers to posterior displacement (backward slip) of a vertebral body relative to one below. Causes include trauma, facet joint osteoarthritis or congenital anomalies (e.g. underdevelopment of the pedicles).