Lateral collateral ligament injuries of the knee are rare in isolation and usually occur in the context of a posterolateral corner injury or in the association of other ligamentous or meniscal injuries.
A lateral collateral ligament injury of the knee is also referred to as the fib...
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 the 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 ...
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 the C2, which is also known as traumatic spondylolisthesis of the axis. Upper neck hyperextension causes bilateral pars interarticularis fractures and the amount and direction of displacement will guide treatment.
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...
Lipohemarthrosis 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 or Casanova 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 he...
There are a vast range of lower extremity fractures. Below are listed several of such fractures of the lower limb. Many have eponyms.
Pelvis and femur
anterior inferior iliac spine avulsion injury
proximal femoral fractures
Lumbar spine fractures are often a result of significant blunt trauma such as motor vehicle accidents or a fall from height. Non-traumatic causes include osteoporotic and pathological fractures.
Traumatic fractures are more common in males. The risk of osteoporotic fractures incre...
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 lung point sign is a highly specific ultrasound sign of pneumothorax. It involves visualizing the point where the visceral pleura (lung) begins to separate from the parietal pleural (chest wall) at the margin of a pneumothorax.
In the absence of pneumothorax, the two pleural layers slide a...
The Macklin effect describes one of the pathophysiological processes of pneumomediastinum in blunt chest trauma. The Macklin effect accounts for ~40% of severe blunt traumatic pneumomediastinum. Exclusion of tracheobronchial and esophageal causes of pneumomediastinum is mandatory to exclude conc...
The Magerl classification, one of many thoracolumbar spinal fracture classification systems, was adopted as the original AO classification in 1994 but has since then been superseded: see the current AO classification of thoracolumbar injuries.
Although the Magerl classification is based ...
Maisonneuve fracture refers to a combination of a fracture of the proximal fibula together with an unstable ankle injury (widening of the ankle mortise on x-ray), often comprising ligamentous injury (distal tibiofibular syndesmosis, deltoid ligament) and/or fracture of the medial malleolus. It i...
Mallet finger refers to injuries of the extensor mechanism of the finger at the level of the distal interphalangeal joint (DIP). They are the most prevalent finger tendon injury in sport. They may represent an isolated tendinous injury or occur in combination with an avulsion fracture of the dor...
A useful mnemonic to remember the most common malunited fractures is:
CSI - Miami
C: Colles fracture
S: scaphoid fracture
I: intertrochanteric femoral neck fracture
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 one of a number of thoracolumbar spinal fracture classification systems and based on the three-column concept of the spine (of Denis). It requires CT for an accurate assessment.
The McAfee classification uses terminology that is...
McGrigor-Campbell lines are imaginary lines traced across the face on an occipitomental (Waters) view skull radiograph to assess for fractures of the middle third (especially) of the face3:
first line is traced from one zygomaticofrontal suture to another, across the superior edge of the orbits...
Medial collateral ligament injuries are one of the most common ligamentous injuries of the knee.
Medial collateral ligament injuries are very common in athletes 1-4 and it is likely that many low-grade medial collateral ligament injuries are unreported 1.
Isolated medial cuneiform fractures are rare, and fractures of the medial cuneiform are more commonly seen in combination with other fractures of the foot.
Most commonly, fractures of the cuneiform bones occur in combination with other fracture-dislocations of the midfoot 3. When...
Medial patellofemoral ligament injuries comprise sprains, tears and ruptures as well as avulsion fractures of the medial patellofemoral ligament (MPFL). They occur regularly in the association with acute traumatic lateral patellar dislocations and are also found in the setting of multi-ligament ...
The Mellado-Bencardino classification of Morel-Lavallée lesions is based on shape, signal and enhancement characteristics, and the presence or absence of a capsule 1:
type I: laminar-shaped and seroma-like with increased T2 signal
type II: oval-shape that resembles a subacute hematoma with in...
Meniscal root tears are 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 meniscal root.
According to one source, they are th...
Metacarpal fractures are common. Fractures of the metacarpal bones account for 10% of all fractures and 40% of all hand fractures. The lifetime incidence of a metacarpal fracture is 2.5%.
Specific names are given to fractures of the base of the first metacarpal (see: fractures of t...
Metal foreign bodies may be present if they are ingested, inserted, or as a result of an injury.
Nearly all metals are radiopaque and can be seen on plain radiographs and CT with the exception of aluminum, which may not be seen on plain radiographs 1,2.
Metaphyseal fractures are fractures that involve the metaphysis of tubular bones. They may occur in pediatric or adult patients.
Examples of metaphyseal fractures:
surgical neck of humerus fracture
distal radial fracture
distal radial buckle frac...
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 visualized on plain radiographs. Ultrasonography can be used in unclear cases.
Treatment and prognosis
Non-displaced fractures can be treated conservatively with a...
The Milch classification is one of the classification 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...
Minimal aortic injury (MAI) is a mild form of blunt traumatic aortic injury which are limited to the aortic intima and are recognized more frequently due to the use of high-resolution vascular imaging in trauma.
Minimal aortic injuries account for 10-28% of all blunt traumatic aor...
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...
The molar tooth sign may refer to:
molar tooth sign (CNS)
molar tooth sign (abdomen)
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.
Morel-Lavallée lesions are closed degloving injuries associated with severe trauma which then present as hemolymphatic masses. MRI and ultrasound are useful modalities for evaluation.
The lesions classically occur over the greater trochanter of the femur 1. Morel-Lavallée lesions, ...
A muscle contusion (a.k.a. muscle bruising or bruise) is a form of muscle injury usually due to direct impact and associated with intramuscular hemorrhage.
Muscle contusions are common injuries and are more frequently seen in males 1,2. In athletes, muscle contusions are the most ...
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 orthopedic 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 hematomas 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 hematomas appear as i...
Nasolacrimal injuries are reported to be common and may result in temporary or permanent dysfunction.
Fracture of the nasolacrimal apparatus has been reported in ~10% of patients with craniofacial fracture, with ~10% of these reporting symptoms of epiphora or dacryocystitis 1.
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...
Navicular fractures along with cuboid fractures form the most common isolated mid-foot fractures.
May present with pain, swelling or hematoma directly over the mid-foot. Stress fractures in athletes and construction workers may present with vague pain and swelling over t...
The Neer classification of clavicular fractures along with the AO classification system is one of the more frequently used classification systems when assessing clavicular fractures.
The classification system, broken into five categories communicates both the stability and treat...
The Neer classification of proximal humeral fractures is probably the most frequently used system along with the AO classification of proximal humeral fractures. The terminology and factors which influence the classification are essential for the utility of radiological reports of proximal humer...
Nerve injury classification describes the various features of nerve injury on MRI with respect to pathological events.
there is increased T2/STIR signal in the nerve, however, the muscle appears normal
recovery occurs within a few days to 3 months
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 meters 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 are uncommon injuries usually resulting from high-energy blunt trauma. They are considered a specific type of basilar skull fracture, and importantly can be seen along with craniocervical dissociation.
Treatment of isolated injury is generally conservative, unless t...
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 clinical signs of a fracture without one actually being seen. MRI or nuclear medicine studies are som...
O'Donoghue unhappy triad or terrible triad often occurs in contact and non-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 an abduction-external rotation mechanism of injury ("pivot s...
Odontoid process fracture, also known as a 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, and with or without compression 5.
There are two...
Esophageal 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 sixties with a slight male predominance 5.
If a perforation is not detected during the proced...
The term off-ended is used by some orthopedic surgeons and radiologists to describe a long bone fracture that is displaced by more than the width of the bone. An off-ended fracture is often shortened due to muscle contraction.
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 (antonym: closed fracture) 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 o...
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. This is typically caused by a direct blow to the central orbit from a fist or ball.
The blowout fracture is the most common type of orbital fracture and is usu...
Orbital compartment syndrome is an ophthalmological emergency referring to an increased intraorbital pressure that may lead to permanent visual impairment if left untreated.
Features usually include:
acute visual impairment
fixed, dilated pupil in ...
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 (OCD) or lesions (OCL) are focal areas of damage with articular cartilage damage and injury of the adjacent subchondral bone plate and subchondral cancellous bone.
Osteochondral defect is a broad term that describes the morphological change of a localized gap...
Osteochondral fractures involve are an articular surface injury involving the articular cartilage and the subchondral bone plate.
Osteochondral fractures appear as a combination of 1,2:
fracture line extending to the joint surface
depression of the subchondral bone pla...
The horizontal beam anteroposterior elbow view for pediatrics is an alternative projection to the anteroposterior view in the elbow series, examining the distal humerus, proximal radius and ulna.
This view is ideal for patients who are unable to move their arm as per the standard ...
The horizontal beam lateral elbow view for pediatrics is an alternative projection to the lateral view in the elbow series, examining the distal humerus, proximal radius and ulna.
This view demonstrates an orthogonal view of the AP elbow and is ideal for patients who are unable to...
The horizontal beam lateral forearm view for pediatrics is one of two modified trauma projections in the forearm series, examining the radius and ulna.
This view is ideal for patients who are unable to move their arm as per the standard forearm positioning technique but require as...
The posteroanterior forearm view for pediatrics is one of two modified trauma projections in the forearm series, examining the radius and ulna.
This view is ideal for patients who are unable to move their arm as per the standard forearm positioning technique but require assessment...
The pancreas is uncommonly injured in blunt trauma. However, pancreatic trauma has a high morbidity and mortality rate. 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 ...
A number of pancreatic injury grading systems have been proposed.
American Association for the Surgery of Trauma (AAST)
grade 1: hematoma with minor contusion/laceration but without duct injury
grade 2: major contusion/laceration but without duct injury
grade 3: distal lacer...
Paranasal sinuses and facial bones radiography is the radiological investigation of the facial bones and paranasal sinuses. Plain radiography of the facial bones is still often used in the setting of trauma, postoperative assessments and dental radiography.
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...
Patellar fracture is one of the common knee injuries usually post direct trauma to the patella or sudden forceful contraction of the quadriceps muscles in the context of a sports injury.
Fractures of the patella represent ~1% all fractures and are most common in those aged 20-50 y...
Patellar sleeve fractures (also commonly, patellar sleeve avulsion fracture) represent chondral or osteochondral avulsion injury commonly at the inferior pole of the patella (including cartilage from the articular surface, as well as periosteum and cartilage over the dorsal surface).
Harrington criteria can be used to predict which long bone skeletal metastases are at high risk of pathological fracture and should undergo prophylactic internal fixation. It preceded the Mirels classification for impending pathological fracture but has not been validated and its use is debated....
Mirels classification is a system used to predict the highest risk of pathological fracture among long bones affected by metastases, and is based on site, location, matrix and/or presence of pain.
involving <1/3 of bone diameter
The PECARN (Pediatric 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 pediatric algorithm predicts likelihood of the abo...
Pectoralis major tears, also known as pectoralis major ruptures, are an uncommon traumatic injury of the pectoralis major.
mostly young, physically-active males age 20-40 years old, although has also reported in elderly women 1
associated with weight lifting (mostly bench press)...
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...
Pelvic binders are external devices commonly used to stabilize the pelvic ring in patients with suspected unstable pelvic fracture.
Most binders have a single metallic buckle, which allows the approximate assessment of their position on pelvic radiographs too. The plasti...