High Ankle Sprain
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High ankle sprain (HAS)
Also known as a syndesmosis injury
Mechanism
Blow to lateral knee whilst running developing ankle pain
Rapid turn on planted foot
Directed blow to the heel
Extreme dorsiflexion
Symptoms
Pain above the joint line
Pain on pushing off from toes
Signs
Ecchymosis may be lacking or pronounced
Difficulty weight bearing
Bimalleolar swelling
Examination
Squeeze (Hopkins) test - squeeze the tibia and fibula together at mid calf produces pain at the syndesmosis.
External rotation and dorsiflexion of the foot produces pain in the syndesmosis.
Positive draw sign of fibula (able to pull the fibula forwards with the Tibia stabilised).
Exclude associated fibula injury mid shaft and at proximal tibiofibula joint.
Radiology
Xray may be unreliable in demonstrating a syndesmosis injury on plain AP and lateral views. If a high index of suspicion request external rotation stress view.
Xray is positive if tibiofibula clear space is greater than 6mm on the AP or mortice view.
Weight bearing stress view may be useful to assess deltoid ligament injury but offer little advantage over plain views otherwise.
Ultrasound has a sensitivity of 61% and a speciality of 91% for AITFL injury.
Management
- Undisplaced high success with non operative.
Below knee non weight bearing moulded POP cast.
Fracture clinic 1 week.
- Displaced refer Orthopaedic for consideration of screw fixation.
Pitfalls
- osteochondral injuries in up to 25%
- peroneal tendon injuries in up to 25%
- Associated deltoid ligament injury,
- complication of webber C fracture in 10%
Syndesmosis injury with widening of the tibia fibula joint
Associated fibula mid shaft fracture with the syndesmosis injury above
HAS fracture clinic
Acute phase
Goal - joint protection whilst minimising risk of DVT and pain.
Joint protection - Immobilisation to avoid external rotation and end range dorsiflexion.
Analgesia - consider short term NSAID, ICE, elevate
Week 1
ROP, transition to polyester tape below knee cylinder cast
X-ray through cast. If no displacement review at week 3. Remain NWB until week 3.
Week 3
ROP, X-ray
Transition to ankle brace or impact boot.
Refer to physiotherapy for non impact mobilisation.
Graduated return to work program from week 3.
Subacute phase
Goal - improve joint mobility, strength and neuromuscular function.
Joint protection - external rotation control brace if work on unfinished surfaces, taping may improve pain control for non impact activity.
Week 6 If not improving at 6 weeks and effusion consider MRI to assess for osteochondral injury.
Return to sport 3 months if pain free, 50% may take up to 6 months.
Complications
- failure of conservative management (ongoing pain) refer for MRI and consideration of screw fixation
- Late synostosis may occur between the tibia and fibula.
- impingement of the distal fascicle of the AITFL may give pain with negative X-ray findings
- late OA from an unstable syndesmosis
Lateral talar dome osteochondral injury
Examination
There are several clinical tests for syndesmosis injury;
- Cotton Push the talus from medial to lateral in the mortice, positive if excessive movement.
- Hopkins Squeeze the Tibia and fibula together mid shaft. Positive if pain felt at the syndesmosis.
- Fibula translation Pull the fibula forward with the tibia fixed, positive if pain in the syndesmosis, best test for instability clinically.
Gross instability is uncommon in cases without associated fracture.
Check for associated injuries - fibula shaft fractures, proximal tibiofibula joint injuries, Webber C ankle fractures. Consider oseteochondral injuries and investigate for exclusion if a high index of suspicion.
High ankle sprain
What is a high ankle sprain?
A high ankle sprain is an injury to the ligaments that hold the bones in the lower leg together at the ankle. This injury is important because those ligaments are required to be able to walk without pain and to be able to run. When you damage or tear those ligaments, which often occurs due to twisting your ankle, you suffer a high ankle sprain. This type of sprain doesn’t occur as often as a sprain in the lower part of the ankle but it can be much more important.
How is it managed?
Treatment depends on the severity of the injury. In mild sprains it may only take a few days and ice, compression and elevation. In more serious cases healing may take as long as six months.
The key problem is determining if the ankle is stable or unstable. What this means is whether the boys try to spread apart when you put your weight on the ankle. This is usually answered by by both a clinical assessment together with X-rays. If the ankle is unstable then further assessment to determine whether surgery is required will be made.
Stable injuries are usually managed in a cast and then a brace. In some cases a different management plan may be required. The first few weeks are usually non weight bearing, therefore crutches and or a knee scooter may be required.
Expected time to work
Return to work in mild cases is usually after a few days. In more serious cases a graduated return to work plan will be made, usually starting around week 3. It may not be possible to get back to full time work for several weeks in rare cases.
Expected time to sport
Return to impact sport can be expected within a few weeks for mild cases, whilst it may be between 3 to 6 months for more serious cases.
A & P
The Talus is shaped as a wedge in both the AP and horizontal planes. If this wedge is rotated in the mortice, or if the wedge is forced to its maximum width (forced dorsiflexion) then the mortice is forced apart.
A high ankle sprain typically occurs when the foot rotates in one direction whilst the leg rotates in the other direction. A typical history is of planting the foot and turning at speed, or of a blow to the lateral knee whilst running. It is most commonly associated with external rotation of the foot. Less commonly the history is of a blow to the heel whilst kneeling or of a forced dorsiflexion injury.
The rotational force applied causes the talus to rotate with respect to the mortice and increases the distracting force experience by the distal tibiofibula syndesmosis. The syndesmosis is made up of 4 primary elements - the anterior and posterior tibiofibular ligaments, the interosseous tibiofibula ligament and the transverse tibiofibula ligament which is a deep portion of the posterior inferior tibiofiibula ligament. The deltoid ligament acts as secondary stabiliser.
The anterior and posterior tibiofibular ligaments are the primary structural elements holding the distal joint together. They are placed under enormous strain and if sufficient force is applied they fail in tension. The force is then transferred to the interosseous ligament and supporting structures and ultimately to the interosseous membrane.
Ankle injuries are common in both adults and children, with the highest incidences of serious injury in young athletes and elderly females.
The mechanism is crucial to determining the likely injury pattern and therefore the appropriate investigation and management.
The diagnosis and therefore management decision can usually be made by a combination of mechanism, examination and plain X-ray.
The soft tissue anatomy is complex and the radiological findings may be difficult to interpret, so seek advice if no bony injury and non weight bearing.
Associated foot and knee injuries are common.
The outcome depends upon recognising the specific injury and managing appropriately.
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