Lower Limb Trauma X-rays

Question 1

Consequences of immobility due to lower limb injury?

Answer 1

• Dehydration and starvation
• DVT/PE
• Pneumonia

Question 2

Imaging modalities that can be used for trauma imaging?

Answer 2

X-rays (can be difficult to assess fractures due to overlapping anatomical fractures)

CT scans (cross-sectional and so is unaffected by overlapping structures)

US (shows superficial soft tissue structres, esp. tendons)

MRI (can show deep soft tissue structures and undisplaced fractures, where no soft tissue density is interposed between bone density fracture margins; an MRI provides details info about bone marrow, so can show undisplaced fractures)

Question 3

How do many lower limb fractures appear?

Answer 3

Many appear sclerotic, as lower limb fractures often involve axial force with BONE IMPACTION

Question 4

Typical sites of lower limb impacted fractures?

Answer 4

Femoral neck

Tibial plateau

Calcaneus (often by jumping out of a window and landing on the heel)

Question 5

Describe pelvic ring fractures?

Answer 5

High-energy fractures, e.g: road-traffic accidents, often occurring in young people; usually multiple, as bony ring disruption typically affects more than one site (either bones or symphisis/SI joints)

They may also be low-energy fractures, typically due to a minor fall (may be of insidious onset)

Question 6

Assessment of high-energy pelvic ring fractures?

Answer 6

X-ray (if the pelvis is the only injured site)

CT is the primary imaging modality in polytrauma patients

Question 7

Assessment of low-energy pelvic ring fractures?

Answer 7

MRI is very sensitive

Question 8

Causes of pelvic soft tissue injury?

Answer 8

Sports-related pelvic injury is common; acutely, it is due to muscle tear or tendon avulsion, e.g: acute hamstring tendon avulsion

Chronic overuse can cause bone/soft tissue pain at tendon/ligament attachment sites

Question 9

Assessment of pelvic soft tissue injuries?

Answer 9

US can show acute injuries affecting superficial structures

MRI is method of choice as it provides complete assessment of all soft tissues and bones

Question 10

Cause of hip dislocation?

Answer 10

Road traffic accidents or contact sports, where the hip is flexed

Typically posterior, with acetabular rim fracture

Question 11

Complications of hip dislocation?

Answer 11

Femoral head AVN

Early OA

Question 12

Types of proximal femoral fractures?

Answer 12

Intracapsular - includes femoral head and neck fractures

Extracapsular - includes trochanteric, intertrochanteric, and subtrochanteric fractures

Question 13

Complications of intracapsular and extracapsular fractures?

Answer 13

Interfere with blood supply to femoral head and can result in femoral head AVN or non-union

Extra-capsular fractures do not cause these

Question 14

Treatment of intracapsular fractures?

Answer 14

Hemiarthroplasty

If undisplaced OR if the patient is young, reduction and screw fixation can be tried

Question 15

Treatment of extracapsular fractures?

Answer 15

Internal fixation

Question 16

What is a proximal femoral fracture cannot be seen but there is clinical suspicion?

Answer 16

Repeat X-ray after 10 days

Immediate MRI, which can show undisplaced fractures

Question 17

Causes and complication of femoral shaft fractures?

Answer 17

Tend to be high-energy fracture and obvious on X-rays

There is a risk of blood loss and fat embolus

Question 18

Injuries of the knee?

Answer 18

Fractures can occur but soft tissue injuries are common

Question 19

What can small avulsed bone fragments in the knee indicate?

Answer 19

Sometimes indicate significant soft tissue injury

Question 20

Soft tissues of the knee that must be examined?

Answer 20

Patellar and quadriceps tendon

Suprapatellar fat space (significant soft tissue injury is usually accom. by an effusion if there is an injury)

Question 21

How can lipohaemarthrosis in the knee be seen?

Answer 21

Horizontal beam laterally can show blood and fat collecting in the suprapatellar recess (specific sign of an intra-articular fracture)

Question 22

How to assess knee dislocation?

Answer 22

Must check bony alignment carefully, as they are often largely reduced by the time the X-ray is done

Question 23

Consequences of knee dislocation?

Answer 23

Complex soft tissue disruption

Potential for popliteal artery injury

Question 24

Describe tibial plateau fractures

Answer 24

Mostly affect the LATERAL CONDYLE, following a valgus force with the foot planted (“bumper injury”)

They can have variable appearances, from an obvious fracture line to subtle subchondral sclerosis

Question 25

Assessment of tibial plateau fractures?

Answer 25

CT scan shows area of condylar involvement/depth of depression

Question 26

Assessment of extensor mechanism injuries?

Answer 26

I.e: quadriceps and patellar tendon tears, can be clarified using US Acute, intra-articular soft tissue injuries may also be difficult to assess clinically due to swelling and pain (shown by MRI)

Question 27

Soft tissue knee injuries shown by MRI?

Answer 27

* Meniscal tears * Cruciate, collateral or other capsular/ligamentous injuries * Hyaline cartilage damage * Subtle fractures

Question 28

Function of mensci?

Answer 28

Fibrocartilaginous medial and lateral menisci buttress knee joint margins, spreading the load between femur and tibia

Question 29

Complications of meniscal tears?

Answer 29

Torn meniscus can displace into the intercondylar notch and patient can present with a "locked knee"

Question 30

Assessment of hyaline cartilage injury?

Answer 30

Predisposes to early OA but is invisible on X-ray MRI can define extent of injury and any resulting loose bodies; it can also assess the success of surgical repair

Question 31

Assessment of undisplaced fractures?

Answer 31

MRI

Question 32

What is a Maisonneuve fracture?

Answer 32

Spiral fracture of the proximal 1/3rd of the fibula, assoc. with a tear of the distal tibiofibular syndesmosis and the interosseous membrane There is an assoc. fracture of the medial malleolus OR rupture of the deep deltoid ligament This type of injury can be difficult to detect

Question 33

Mechanism of ankle injury?

Answer 33

Inversion or eversion usually

Question 34

Assessment of ankle injuries?

Answer 34

X-ray (AP and lateral views) CT can be helpful to clarify fracture anatomy US and MRI may be needed to define soft tissue injury

Question 35

Signs of ankle fractures?

Answer 35

Soft tissue swelling Confirm uniform joint space (non-uniform joint space indicate instability, often with ligamentous damage) Look for malleolar fractures, which may be solitary, as they are often avulsion or undisplaced fractures (look carefully at the lateral view for undisplaced fractures)

Question 36

Describe ankle fractures

Answer 36

Tend to be multiple and can affect the: • Lateral malleolus • Medial malleolus • Posterior malleolus (posterioinferior tibia)

Question 37

What is a tarsal dome margin fracture?

Answer 37

Excessive inversion or eversion can cause injury to the cartilage and underlying bone of the talus within the ankle joint; this can cause chronic pain/instability

Question 38

Diagnosis of tarsal dome margin fractures?

Answer 38

MRI

Question 39

What is a 5th metatarsal base fracture?

Answer 39

Follows inversion and clinically resembles a lateral malleolar fracture, so check this area on lateral X-ray They are transerve and resemble a normal longitudinal ossification centre

Question 40

What is a calcaneal fracture?

Answer 40

Usually follows axial compression, such as falling from a height onto the heel; they are often comminuted Normal calcaneus has a central peak but fracture causes loss of this peak and increased bone density

Question 41

Accessory ossification centres and when & where they are seen?

Answer 41

* In adolescents, the 5th metatarsal has a longitudinal accessory ossification centre at its base * Fragmented accessory ossification centre is normally seen along the posterior calcaneus in children * Fabella is a sesamoid bone within the lateral head of the gastrocnemius, often visible posterior to the proximal femur * Os trigonum is commonly seen posterior to the talus * Rounded sesamoid bones may arise at multiple sites within the foot, but are invariably present on the medial and lateral plantar aspects of the 1st metatarsal head

Question 42

Most common ankle tendon injuries?

Answer 42

Achilles and most other ankle tendon can be affected Tendon rupture may follow a single high-energy event but is often due to recurrent minor tears

Question 43

Factors that predispose to tendon rupture?

Answer 43

DIABETES, RA and STEROIDS

Question 44

What is a lisfranc fracture?

Answer 44

1/more of the metatarsal bones are displaced from the tarsus; usually, several TMT joints are involved with multiple ligamentous avulsion fractures, shown best by CT