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...
Knee dislocations are rare, but a significant number have serious associated vascular injury. They account for <0.5% of all joint dislocations.
This article discussed tibiofemoral joint dislocation. Please see separate articles for discussion of medial and lateral patellar dislocation.
Large joint dislocation is a not uncommon presentation to emergency rooms. Described in order of comonality:
posterior dislocation of the hip
Laryngeal trauma is uncommon in the setting of external blunt or penetrating trauma. The larynx may also be injured internally, for example during endotracheal intubation.
Symptoms include hoarseness, laryngeal pain, dyspnoea, and/or dysphagia. Also, stridor, haemoptysis,...
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, ...
Lateral patellar dislocation refers to lateral displacement followed by dislocation of patella due to disruptive changes to the medial patellar retinaculum.
Patellar dislocation accounts for ~3% of all knee injuries and is commonly seen in those individuals who participate in spor...
Lateral talar process fractures or snowboarder fractures are talus fractures that can mimic a lateral ankle sprain. It may be an isolated fracture or occur as a component of more complex ankle fractures.
The fracture occurs when the foot is dorsiflexed and inverted, as can happen wit...
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
The lightbulb sign refers to the abnormal AP radiograph appearance of the humeral head in posterior shoulder dislocation.
When the humerus dislocates it also internally rotates such that the head contour projects like a lightbulb when viewed from the front 1.
light bulb sign (hepatic...
Lipohaemarthrosis results from an intra-articular fracture with escape of fat and blood from the bone marrow into the joint, and is most frequently seen in the knee, associated with a tibial plateau fracture or distal femoral fracture; rarely a patellar fracture. They have also been described in...
Lisfranc injuries, also called Lisfranc fracture-dislocations, are the most common type of dislocation involving the foot and correspond to the dislocation of the articulation of the tarsus with the metatarsal bases.
The Lisfranc joint is the articulation of the tarsus with ...
The liver is one of the most frequently damaged organs in blunt trauma, and liver trauma is associated with a significant mortality rate.
In blunt abdominal trauma, the liver is injured ~5% (range 1-10%) of the time 1,3.
Patients can present with right uppe...
Locked facet joint is a type of facet joint dislocation that results from jumping of the inferior articular process over the superior articular process of the vertebra below and becomes locked in the position.
It can be unilateral or bilateral.
The tip ...
Longitudinal temporal bone fractures are petrous temporal bone fractures that occur parallel to the long axis of the petrous temporal bone. Although more current classifications of the extent of temporal bone fractures focus on the integrity of the otic capsule rather than the fracture orientati...
Petrous temporal bone fractures are classically divided into longitudinal, transverse or mixed fracture patterns depending on the direction of fracture plane with respect to the long axis of the petrous temporal bone. Some features may aid in distinguishing them.
Lover's fracture, also known as Don Juan fracture, is a type of calcaneal fracture. They are fractures of the calcaneal body and may be intra- or extra-articular.
History and etymology
The name "lover's fracture" is derived from the fact that a suitor may jump from great heights while trying t...
Lunate dislocations are an uncommon traumatic wrist injury that require prompt management and surgical repair. The lunate is displaced and rotated volarly. The rest of the carpal bones are in a normal anatomic position in relation to the radius.
These should not be confused with perilunate disl...
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
Maisonneuve fracture is the combination of a spiral fracture of the proximal fibula and unstable ankle injury which could manifest radiographically by widening of the ankle joint due to distal tibiofibular syndesmosis and/or deltoid ligament disruption, or fracture of the medial malleolus. It is...
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.
Mandibular fractures are relatively common especially among young men. Although traditionally the mandible and base of skull are thought to form a complete bony ring, interrupted only by the TMJs. This should mean that the mandible should fracture in two places (akin to the bony pelvis) making s...
The Marshall classification of traumatic brain injury is a CT scan derived metric using only a few features and has been shown to predict outcome in patients with traumatic brain injury.
This system was first published in 1992 1 building on findings from a large cohort of head injury cases des...
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...
McGrigor-Campbell lines are imaginary lines traced across the face on an occipitomental (Waters) view skull radiograph to assess for fractures:
first line is traced from one zygomaticofrontal suture to another, across the superior edge of the orbits
second line traces the zygomatic arch, cross...
A meniscal root tear is a type of meniscal tear in the knee where the tear extends to either the anterior or posterior meniscal root attachment to the central tibial plateau. They often tend to be radial tears extending into the root.
According to one source they are thought to a...
Metacarpal fractures are common. Fracture of the metacarpal bones accounts for 10% of all fractures and 40% of all hand fractures. The lifetime incidence of a metacarpal fracture is 2.5%.
Specific names are given to fractures of the base of the first metacarpal (see: fractures of t...
Metaphyseal fractures are fractures that involve the metaphysis of tubular bones. They may occur in paediatric or adult patients.
Examples of metaphyseal fractures:
surgical neck of humerus fracture
distal radial fracture
distal radial buckle fra...
Midcarpal (central carpal) dislocation describes an injury where there is dislocation of the capitate from the lunate, and subluxation of the lunate from the radius. This term is somewhat confusing because some authors use "midcarpal dislocation" to refer generally to perilunate and lunate dislo...
Middle phalanx fractures are the least common of the phalanx fractures.
These fractures are generally well visualised on plain radiographs. Ultrasonography can be used in unclear cases.
Treatment and prognosis
Non-displaced fractures can be treated conservatively with a...
Minimal aortic injuries are traumatic aortic lesions that usually involve the intima and are recognised more frequently due to the use of high-resolution imaging.
Minimal aortic injuries account for 10-28% of all blunt traumatic aortic injuries 1,6,7. The proportion of this type o...
Mixed temporal bone fractures are a combination of longitudinal and transverse fracture types, and are probably the most common type. They frequently involve the otic capsule, and are associated with both conductive and sensorineural hearing loss.
The modified Memphis criteria are a set of screening criteria for blunt cerebrovascular injury (BCVI) in trauma. The presence of one or more of these criteria makes necessary a complementary CTA or DSA study to exclude a BCVI.
The screening protocol criteria for BCVI are:
base of skull fractur...
Monteggia fracture-dislocations consist of a fracture of the ulnar shaft with concomitant dislocation of the radial head. The ulnar fracture is usually obvious, whereas the radial head dislocation can be overlooked, with potentially serious functional and medico-legal ramifications.
A Morel-Lavallée lesion is a closed degloving injury associated with severe trauma which then presents as a haemolymphatic mass. MRI and ultrasound are useful modalities for evaluation.
The lesions classically occur over the greater trochanter of the femur 1. Morel-Lavallée lesions...
This is a basic article for medical students and other non-radiologists
The medical student musculoskeletal radiology curriculum represents a core set of common pathologies and presentations that are key to understand during any orthopaedic attachment in medical school.
Named fractures are usually eponymous or occupational. The simplest way of spiting them up is by body area:
upper extremity fractures
lower extremity fractures
Nasal bone fractures are the most common type of facial fractures, accounting for ~45% of facial fractures, and are often missed when significant facial swelling is present.
Unsurprisingly, nasal bone fractures occur when the nose impacts against a solid object (e.g. fis...
Nasal septal haematomas arise from ruptures in the small blood vessels in the nasal septum and are largely secondary to trauma. The nasal septum has a rich vascular supply which sources from both the internal and external carotid arteries.
Septal haematomas appear as...
Naso-orbitoethmoid (NOE) fractures (also known as orbitoethmoid or nasoethmoidal complex fractures) are fractures which involve the central upper midface.
Naso-orbitoethmoid fractures are caused by a high-impact force applied anteriorly to the nose and transmitted posteriorly through...
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...
NEXUS Chest is a clinical decision rule that supports the appropriate use of thoracic imaging in trauma. There are seven criteria 1,2:
>60 years old
rapid deceleration defined as fall > 6 metres or motor vehicle crash >64 km/hour
abnormal alertness or mental status
Nightstick fractures are isolated fractures of the ulna, typically transverse and located in the mid-diaphysis and usually resulting from a direct blow. It is a characteristic defensive fracture when the patient tries to ward off an overhead blow from an assailant (or local law enforcement offic...
Oblique fractures are complete fractures that occur at a plane oblique to the long axis of the bone. Like transverse fractures, the term is predominantly used in the context of describing a fracture in a long bone.
Oblique fractures are particularly prone to angulation in the plane of the fract...
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.
Occult fractures are those that are not visible on imaging, most commonly plain radiographs and sometimes CT, either due to lack of displacement or limitations of the imaging study. There may be signs of a fracture without one actually being seen. MRI or nuclear medicine studies are sometimes re...
O'Donoghue unhappy triad or terrible triad often occurs in contact sports, such as basketball, football, or rugby, when there is a lateral force applied to the knee while the foot is fixated on the ground. This produces the "pivot shift" mechanism.
The O'Donoghue unhappy triad comprises three t...
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...
Oesophageal perforation is a rare but serious medical emergency with a very high mortality rate, especially if the diagnosis is delayed.
Most patients are in their 60s with a slight male predominance 5.
If a perforation is not detected during the procedure...
Olecranon fractures are clinically and radiographically obvious, and usually require open reduction and internal fixation.
Olecranon fractures occur as the result of one of four mechanisms 2:
direct blow (or fall directly on the elbow)
fall on outstretched hand with elbow flexed
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...
An open or compound fracture or dislocation refers to a fracture or dislocation associated with soft tissue injury where the fractured bone or dislocated joint is in direct communication with the outside environment.
It is of surgical importance due to the high risk of microbial contamination a...
Orbital blow-in fractures occur when there is displacement of bone fragments towards the orbits.
blow-in fracture effectively reduces the volume of the orbit
associated intraorbital injuries include extraocular muscle entrapment and optic nerve injury
as an isolated (pure) orbital ...
Orbital blowout fractures occur when there is a fracture of one of the walls of orbit but the orbital rim remains intact. Typically, this is caused by a direct blow to the central orbit from a fist or ball.
The blow-out fracture is the commonest type of orbital fracture and is usu...
Orbital emphysema is the presence of gas within the orbital soft tissues. It is usually due to orbital fractures communicating with the paranasal sinuses but can be caused by penetrating trauma and infection. It is a common finding also after orbital or ocular surgery.
Ossicular chain disruption (or ossicular discontinuity) is loss of normal alignment between the three middle ear ossicles. The condition is a cause of conductive hearing loss.
Exact incidence and prevalence are not known. Hearing loss associated with temporal bone fractures in chi...
Osteochondral defects are focal areas of articular damage with cartilage damage and injury of the adjacent subchondral bone. It is a term that encompasses osteochondritis dissecans and is used synonymously with osteochondral injury/defect in the paediatric population.
The pancreas is uncommonly injured in blunt trauma. However, pancreatic trauma has a high morbidity and mortality. Imaging features range from subtle to obvious.
The pancreas is injured in ~7.5% (range 2-13%) of blunt trauma cases 1,3. Motor vehicle accidents account for the vast ...
A number of pancreatic injury grading systems have been proposed.
American Association for the Surgery of Trauma (AAST)
grade 1: haematoma with minor contusion/laceration but without duct injury
grade 2: major contusion/laceration but without duct injury
grade 3: distal lace...
Paranasal sinuses are air-filled cavities surrounding the nasal cavity proper which includes maxillary sinus, sphenoid sinus, frontal sinus and ethmoid sinus. Trauma to the superior and middle thirds of the face can often lead to in paranasal sinus fractures involving one or more paranasal sinus...
Patella fracture is one of the common knee injuries usually post direct trauma to the patella or sudden forceful contraction of the quadriceps muscles in a context of sports injury.
Patients present with marked swelling and pain over the patella with point tenderness and ...
Patellar sleeve fractures represent chondral or osteochondral avulsion injury at the inferior pole of the patella.
Patellar sleeve fractures occur in the paediatric population, typically between 8 and 12 years of age.
Unlike Sinding-Larsen-Johannson disease...
Pathological fractures are fractures that occur in abnormal bone. Although the term can be used in the setting of a generalized metabolic bone disease, it is usually reserved for fractures through a focal abnormality. The abnormality may be malignant or non-malignant in nature.
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
The PECARN (Paediatric Emergency Care Applied Research Network) traumatic brain injury algorithm is a clinical decision rule that aims to identify children at very low risk of clinically important traumatic brain injury (ci-TBI) 1. This validated paediatric algorithm predicts likelihood of the a...
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...
Bucket handle fractures of the pelvis are a result of anteroposterior compression energy vectors. It is described as a vertically-orientated fracture through ipsilateral superior and inferior pubic rami with contralateral sacroiliac joint disruption/dislocation 1, 2.
Pelvic fractures can be simple or complex and can involve any part of the bony pelvis. Pelvic fractures can be fatal, and an unstable pelvis requires immediate management.
Pelvic fractures can be seen in any group of patients. Like much trauma, there is a bimodal distribution with...
This is a basic article for medical students and other non-radiologists
Pelvic fractures are a heterogeneous group of injuries that can occur secondary to a variety of mechanisms that range from an innocuous simple fall to severe high-energy trauma in a road traffic collision.
Penetrating thoracic trauma, namely gunshot and stab injuries, vary widely in incidence globally but nevertheless result in high mortality and serious morbidity. CT is the modality of choice in imaging these patients and can reduce the need for surgical exploration.
Penetrating traumatic neck injury can be a potentially devastating injury due to the high density of crucial anatomical structures within the neck.
Young males are highly represented in patients with a traumatic neck injury. In one study, 11:1 ratio of males to females were ident...
Penile fracture is a rare event, however requires emergency diagnosis and intervention.
It is a rupture of corpora cavernosa and penile sheath (tunica albuginea) caused by trauma to an erect penis, most commonly during sexual intercourse. What a urologist needs to known in such an emergency, is...
Perched facet joint is a vertebral facet joint whose inferior articular process appears to sit 'perched' on the ipsilateral superior articular process of the vertebra below.
Any further anterior subluxation will result in dislocation, with one facet "jumping" over the other and becoming locked ...
Perilunate dislocations and perilunate fracture dislocations are potentially devastating closed wrist injuries that are often missed on initial imaging.
These injuries involve dislocation of the carpus relative to the lunate which remains in normal alignment with the distal radius. They should...
Periprosthetic fractures can occur around any joint replacement and commonly occur around knee and hip arthroplasties.
Periprosthetic fractures complicate around 1% of total hip arthroplasties and ~1.5% of total knee arthroplasties 1,2.
They can be difficul...
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
Peritalar dislocation, also referred to as subtalar dislocation, involves the combined dislocation of the talocalcaneal/subtalar and talonavicular joints without the involvement of the tibiotalar and calcaneonavicular joints. It is generally associated with high-energy trauma and accounts for a ...
Perthes lesion of the shoulder is one of the types of the anterior glenohumeral injury in which the anterior inferior labrum is torn and lifted from the edge of the glenoid 1 but still attached to the intact lifted periosteum from the anterior aspect of the glenoid. Although the labrum may be no...
Phalanx fractures are common injuries, although less common than metacarpal fractures. They have different prognosis and treatment depending on the location of the fracture.
Phalanx fractures can be intra- or extra-articular and can occur at the base, neck, shaft or head of the phala...
Phthisis bulbi, also known as end-stage eye, is an atrophic scarred and disorganised globe that may result from a variety of severe ocular insults.
The globe is reduced in size (usually <20 mm) with a thickened/folded posterior sclera. Dystrophic calcification is common, and osseous...
Physiological pelvic intraperitoneal fluid refers to the presence of a small volume of free fluid in the pelvis, particularly the pouch of Douglas. It occurs in young females of reproductive age and can be a mimic of traumatic free fluid in abdominal trauma.
Unfortunately, pelvic free fluid may...
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...
A pilon fracture is a type of fracture involving the distal tibia. These are considered to represent 1-10% of all lower limb fractures 6.
Typically occurs as a result of an axial loading injury which drives the talus into the tibial plafond.
Several classification s...
Ping pong skull fracture or pond skull fracture refers to a depressed skull fracture of the infant skull caused by inner buckling of the calvarium. It is seen in newborns because of the soft and resilient nature of their bones (like greenstick fractures of long bones) and the fracture line is no...
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...
Pisiform fractures are an uncommon type of fracture involving the carpal bones.
They are only thought to account ~0.2% of all carpal fractures. Approximately 50% occur in association with other carpal fractures.
Some can be occult on plain...