All examination findings should be compared to the non-injured side to rule out ‘normal’ joint laxity.
Tests for instability should be performed in the anterior-posterior plane using the anterior draw test (Fig.2) and inversion- eversion plane using the inversion test (Fig.3). The anterior draw test identifies
Typical appearance of lateral ligament damage
There will be swelling over the lateral aspect of the ankle joint extending to the forefoot with bruising in the same region often extending to the toes. Soft tissue swelling may be seen around the whole ankle joint due to infiltration of oedema and both active and passive movements will be reduced.
The whole area should be palpated to identify all points of tenderness. After examining the malleoli it is important also to check the cuboid, calcaneum and base of the fifth metatarsal as these can be involved in inversion injuries.
Swelling and tenderness over the fibula suggests an underlying fracture, whereas its presence over the lateral ligament complex is likely to indicate ligamentous injury.
If a ligamentous injury is suspected each component of the lateral ligament should be carefully examined to try and identify the extent of damage.
Diagnostic tests
The easiest way of assessing joint effusion (blood/fluid escaping into a cavity due to inflammation) is with the patient prone. The concavity at either side of the Achilles tendon is likely to be lost and this suggests a significant injury. However, severe injuries may rupture the capsule and no effusion will be found.
In the acute situation (
When to X-RAY
X-rays are not indicated in simple Grade 1 sprains where the patient can weight- bear on the affected limb and has isolated tenderness over the ATFL. Inability to weight-bear and bone tenderness are indications to x-ray (see the Ottawa rules).
Figure 3: Inversion test
tears of the anterior talofibular ligament and is performed with the ankle in neutral by grasping the heel in one hand and pulling forwards while the tibia is held and pushed backwards. The inversion test indicates more serious injury perhaps involving the other ligaments in the lateral complex (deltoid and calcaneofibular ligaments) and is performed by inverting the ankle and feeling for instability.
A lateral x-ray should also be requested as avulsion fractures of the fibula and spiral fractures of both the tibia and fibula can occur.
When requesting plain radiographs a mortice view provides a better assessment of the joint and the articular surfaces than a routine anteroposterior film in which the fibula overlies the lateral talar dome, a common site for osteochondral fractures.
THE OTTAWA ANKLE RULES
In general fewer than 15% of ankle x-rays show an abnormality. This is an expensive and very inefficient use of radiography. Use of the Ottawa Rules have been proven to lead to a decrease in radiography waiting times and costs without an increase rate of missed fractures. They are based on areas of bone tenderness and assessment of ability to bear weight. The Rules allow doctors to determine quickly which patients are at negligible risk of fracture.
A) Posterior edge or tip of lateral malleous
C) Base of 5th Metatarsal
MALLEOLAR ZONE 6cm MIDFOOT ZONE 6cm
B) Posterior edge or tip of medial malleous
D) Navicular
LATERAL VIEW An ankle x-ray series is only required if:
There is any pain in malleolar zone and any of these findings: 1. Bone tenderness at A (or) 2. Bone tenderness at B (or)
3. Inability to bear weight both immediately and in emergency department
Figure 2: Anterior draw test SportEX 25
MEDIAL VIEW A foot x-ray series is only required if:
There is any pain in midfoot zone and any of these findings: 1. Bone tenderness at C (or) 2. Bone tenderness at D (or)
3. Inability to bear weight both immediately and in emergency department