inversion injuries often fracture the base of 5th MT, or may cause a Jones fracture (location at the metadiaphyseal junction at proximal fifth metatarsal), thus if tender, Xray foot
palpate for tenderness over the proximal fibula to exclude potential Maisonneuve fracture (proximal fibular fracture associated with medial-sided and syndesmotic injury)
examine closely to exclude possibility of open fracture (ie. breach of skin) which needs early orthopaedic Mx.
osteochondral fractures of the talar dome are easily missed on routine Xrays, therefore, persistent ankle pain may require additional imaging studies
adults
lateral ankle sprains account for ~90% of adult ankle injuries
ankle fractures occur in ~15% of those who present to doctors
most unstable ankle fractures in adults are the result of excessive external rotation of the talus with respect to the tibia:
if the foot is supinated at the time of external rotation, an oblique fracture of the fibula ensues
if the foot is pronated at the time of external rotation, a mid- or high-fibular fracture results
displaced fracture/dislocations of the ankle MUST be reduced ASAP within minutes to reduce risk of skin breakdown
adults placed in back slab or cast, or a moon boot should have a formal VTE assessment, and if at high risk, should be considered for VTE prophylaxis with enoxaparin
currently, most orthopaedic surgeons advise that those without high risk are generally NOT given anticoagulation as risks outweigh benefits
recent research shows that risk of fatal PE in all patients with these injuries requiring immobilization is extremely low - perhaps 1 in 5000, but giving anticoagulants does double rates of adverse effects although also decreases symptomatic DVTs (need to treat 14 patients to have 1 less symptomatic DVT). There is as yet no reliable evidence to prove that anticoagulation reduced fatal PEs in this group.
all adults immobilized as above should be given a VTE patient advice sheet:
in children, tenderness over the lateral malleolus suggest a type I Salter-Harris classification of epiphysial plate injury, even if radiographic findings are negative, although fortunately, most can be managed as for a severe sprain.
SHII fractures of the distal tibia are common and best seen on the lateral view as the distal tibia epiphysis displacing anterior to the tibial shaft - these usually require early (< 1 week) closed reduction.
a Tillaux fracture is a SHIII fracture involving the anterolateral tibial epiphysis that is commonly seen in adolescents and may require early ORIF if remains displaced > 2mm.
a longitudinal lucency at the base of the 5th metatarsal is the growth plate of the apophysis and NOT a fracture.
a transverse lucency at the base of the 5th metatarsal suggests a fracture NOT a growth plate.
children also not uncommonly have fractures across the necks or the bases of the 2nd-4th MT's - have a lower threshold for Xray of painful feet after a fall.
young children often present with a limp after a minor fall and there are no obvious areas of tenderness - these children should have a tibia and fibula Xray to exclude a toddler fracture of shaft of tibia.
is an Xray really needed?
only ~15% of patients presenting with ankle injuries will have a fracture on Xray
for the remainder, although there is some psychological reassurance from doing an Xray, it adds cost, time, contributes to ED overcrowding, and adds more radiation exposure unnecessarily.
use of the Ottawa ankle rules to decide on who should have an Xray, can reduce the number of adult ankle Xrays required to ~35% of patients presenting, whilst still picking up nearly all significant fractures.
the main barrier to their use is patient acceptance and physician awareness and preparedness to use them.
has diminished ability to follow the test (for example due to head injury or intoxication)
child (under the age of 18) - although some evidence to support use in this age group, but not the foot rules
X-rays are only required if there is bony pain in the malleolar zone and any one of the following:
bone tenderness along the distal 6 cm of the posterior edge of the tibia or tip of the medial malleolus
bone tenderness along the distal 6 cm of the posterior edge of the fibula or tip of the lateral malleolus
an inability to bear weight both immediately and in the emergency department for four steps.
in addition, foot Xray is required according to the Ottawa Foot Rules if either:
there is bony pain in the midfoot zone, and any one of the following:
bone tenderness at the base of the fifth metatarsal
bone tenderness at the navicular bone
an inability to bear weight both immediately and in the emergency department for four steps
Mx of the sprained ankle
patients with severe sprains as evidenced by substantial swelling and/or bruising appear to gain earlier mobility if placed in a below knee plaster cast or backslab for the first 10 days1), followed by physiotherapy.
the early immobilised group had better results at 3 months but equal results at 12 months
other patients are usually managed by a period of RICE - Rest, Ice, Compression with tubigrip bandage, and Elevation followed by physiotherapy.
The goal of rehabilitation should be symmetric range of motion and 85% of contralateral strength prior to returning to sport.
nomenclature for ankle fractures
ankle fractures can be classified as single malleolar, bimalleolar, and trimalleolar if the posterior part of the tibial plafond is involved.
bimalleolar or trimalleolar injuries are always unstable and are treated with open reduction and internal fixation (ORIF).
barely visible osseous chip fractures do not alter the routine active management of grade 1 and 2 ankle sprains.
careful attention must be paid to all single malleolar fractures because ligament instability is frequently associated with the contralateral side.
in the presence of medial malleolar tenderness and more than 5 mm of medial clear space on the mortise view, make a presumptive diagnosis of deltoid ligament rupture if a displaced fibular fracture is present. Treat these injuries as unstable bimalleolar fracture warranting orthopaedic opinion +/- ORIF.
distal fibula fractures are the most common fracture type to the ankle, and the Danis-Weber classification system is listed below.
simple Danis-Weber classification of lateral malleolar fractures
Weber A
transverse fracture of fibula BELOW the level of the ankle joint
stable and can be managed by closed reduction if needed
may require ORIF if associated with a displaced medial malleolar fracture
Weber B
spiral fracture of fibula AT the level of the ankle joint
occurs secondary to external rotational forces
may require ORIF depending on ligamentous injury or associated fractures on the medial side
Weber C
fracture ABOVE the level of the ankle joint
disrupts the ligamentous attachment between the fibula and the tibia distal to the fracture
unstable - needs ORIF
Maisonneuve fracture
caused by a pronation-external rotation mechanism
~half of cases are sports injuries
if left untreated, instability of the tibiotalar joint and deltoid ligament can cause a valgus deformity of the ankle leaving the ankle joint in a state of chronic pronation, characterised by a protrusion of the medial malleolus into the subcutaneous tissue
injuries seen in a complete picture:
spiral fracture proximal fibula (Weber C), plus,
fracture medial malleoulus, plus,
tear in the distal tibiofibular syndesmosis, plus,
tear in the interosseous membrane, plus,
rupture of the deep deltoid ligament of the ankle
this results in widening of the ankle mortise on x-ray
usual Rx:
internal fixation of the distal tibiofibular syndesmosis
reduction and stabilisation of medial malleolus fracture