Definition
Partial or complete rupture of one or parts of lateral ligaments of ankle
- common ankle sprain
Epidemiology
Lateral ligaments sprains are the most common ligamentous injuries of the human body
- account for approximately 15% of all athletic injuries
- it is estimated that there is one ankle inversion injury per day per 10,000 people
Most common young males
- average age 27
- M:F 2.5 : 1
- common injury in sport
- basketball & soccer
- 10% emergency consults
NHx
Up to 20% to 40% of ankle sprains treated conservatively have some residual symptoms
- undertreatment is more common than overtreatment
- inadequate treatment can result in chronic ankle instability with recurrent sprains and early degenerative arthritis
- 10% of lateral ligament injuries will have subtalar instability also
Aetiology
Inversion injury
- jumping sports
- land plantarflexed and inverted
Associations
Peroneal muscle weakness
Pes Cavus
Tarsal Coalition
Anatomy
The ankle is a uniaxial joint that resembles a mortise and tenon
It is very stable when loaded in the neutral position
- bony contact and stability decrease with plantar flexion
1. ATFL
The most frequently injured ligament in the human body
Dimension
- 15 to 20 mm long, 6 to 10 mm wide, and 2 mm thick on average
Anatomy
- arises anterior aspect fibula, 1 cm above tip, 2 cm long, attaches 8 mm above STJ
Action
- primary restraint to anterior displacement, internal rotation, and inversion of the talus at all flexion angles
- in cadaveric studies, the ATFL always failed first
2. CFL
Cylindrical structure
- lies deep to the peroneal tendons
- 2.5 times stronger than the ATFL
Dimension
- 20 to 30 mm long, 3 to 5 mm thick, and 4 to 8 mm wide
Anatomy
- arises tip fibular, 2 cm long
- subtends angle 130 degrees from fibula
- attaches 13 mm below STJ
Action
- crosses two joints and acts as a subtalar joint stabilizer
- isolated CFL ruptures rare
- the ATFL and the CFL function together at all positions of ankle flexion to provide lateral ankle stability
3. PTFL
The strongest of the lateral ligaments
- least often injured
Dimensions
- 30 mm long, 5 mm wide, and 5 to 8 mm thick
Anatomy
- medial surface of lateral malleolus to posterior lip talus
Pathology
Most are mid-substance tears
- avulsion injuries occur in about 14%
Findings
- isolated ATFL tear is most common injury(60% to 70%)
- combined ATFL / CFL tear (20%)
- isolated CFL, PTFL, & subtalar ligament ruptures all very rare
Examination
Tenderness
Fingertip palpation of all structures
- shown to be almost as accurate and more cost-effective than the tests available
Instability testing
Controversial & unreliable without anaesthesia in acute setting (LA or GA)
1. Anterior drawer
Most important & best predictor ATFL
- 10° plantarflexion neutral rotation
- CFL plays no role
> 3mm is positive
2. Talar tilt
CFL test / subtalar instability
- 10% of patients with lateral ligament instability also have subtalar instability
Patient seated / foot unsupported
- 10-20° PF
- stabilise tibia / gentle inversion
- compare to other side
> 20o abnormal
Investigations
X-rays
Advisable with significant ankle injuries / unable to weight bear
- AP, Mortise & Lateral views
- +/- AP Foot
Look for OCD / Weber A fibula
High resolution CT & MRI
Exclude OCD if needed
Not required acutely
Define injury in chronic situation
Grading Acute Injury
Grade I
Mild injury with minimal swelling and tenderness and slight or no functional loss
- ankle is stable
- negative drawer and talar tilt tests
Considered to be a partial tear
- patient can perform normal activities but with pain
Grade II
Moderate injury with diffuse swelling and tenderness
- moderate functional loss with difficulty with toe walking
- partial stability is lost
- mildly positive anterior drawer (ATFL complete tear)
- negative talar tilt (CFL partial tear only)
Partial to possibly complete tear of the ATFL and a possible partial tear of the CFL
- patient cannot perform normal activities and can bear weight but with increased pain
Grade III
Severe injury
- significant functional loss and marked tenderness, swelling, and pain
- lateral ankle stability is lost
- positive drawer and talar tilt tests
Considered to signify a double ligament injury with complete rupture of the ATFL and CFL
- weight bearing is usually not tolerated
Acute Management
Grade I & II Injuries
Mechanically stable
Benefit from protection
- stirrup-type brace or high boot
- until nonprotected weight bearing is relatively pain-free
During the protected period
- non-weightbearing ROM exercises are performed
Progressing to proprioceptive & ultimately agility training
- shown to shorten the period of disability
- Grade I ankle sprain should be near full recovery at 1-2 weeks
- Grade II ankle sprain at 2-3 weeks (may take a lot longer)
Grade III Injuries
Mechanically unstable by definition
Previously thought to all require surgery but now shown to be successfully treated non-operatively
1. Casting for 4-6 weeks
- in slight dorsiflexion & eversion to approximate ligament ends
- then functional rehabilitation
2. Functional Bracing
- removable brace
- progressive weightbearing
- ROM, proprioception & strengthening exercises
- success demonstrated with MRI studies
Rehabilitation
Kannus Meta-analysis
Functional treatment superior in
- time to return to work
- physical activity
- ROM
- less wasting
- complications
No difference in
- instability
- pain, swelling & stiffness
- re-injury
Protocols
Strapping
- figure 8 weave
- in neutral DF & slight ER
- shortens ATFL & helps proprioception
Physiotherapy
- peronei rehab is the key
- proprioception exercises
Return to Sport
- successful performance of simple tests provide adequate guidelines
- ability to run, cut and jump 10 times on the single injured foot
- to stand on one foot with eyes closed for one minute
- all without excessive pain
- athletes can return to sports when they are able to run and pivot without pain while the ankle is braced
- bracing or taping for sports is continued for 6 months after injury
Outcome
Most return to work by 8/52
20% have pain that limits activity
20 - 40% will have recurrent sprains