Ankle injuries are a ridiculously common sports injury. Fong et al (2007) found that ankle injuries are the most common injuries in a wide variety of popular sports. It has been suggested that syndesmosis injuries account for about 11% of these ankle injuries (Williams & Allen, 2010; Mulligan, 2011). Furthermore, ankle syndesmosis injuries (or “high” ankle sprains) have high occurences during athletic activities, particularly those that involve twisting or cutting activities (think Benji Marshall / Brandon Lloyd / Ronaldo : to cover most countries!)
This means that you sports physiotherapists will regularly see these injuries. It is very important that you are aware of EBP for this condition.
Whilst I won’t labour the anatomy (you guys would all know it anyway….wouldn’t you?). However, I just wish to discuss the contributions of the ligamentous restraints of the distal tibiofibular joint (Ogilvie-Harris et al., 1994):
- Anterior Inferior Tibio-fibular Ligament: Provides ~ 35% of the restraint. Travels inferiorly in a medial to lateral direction.
- Posterior Inferior Tibio-fibular Ligament: Provides ~ 40% of the restraint. Stronger and thicker than the AITFL.
- Interosseous Membrane: Provides the remaining ~ 25% of the restraint.
Again, the biomechanics are most likely well understood, I think it is important that I confirm one point. The inferior or distal tibio-fibular joint is a fibrous syndesmotic joint. It spreads to accommodate the trapezoidal talus (which is 3-4mm larger anteriorly than posteriorly) during dorsiflexion.
The following table displays the concurrent movements of the ankle, talus and fibula:
Mechanism Of Injury
Given our re-found understanding of the anatomy and the biomechanics, we can the discuss the mechanisms of injury for injury to the distal tibio-fibular joint or syndesmosis. The syndesmotic ligaments are challenged by excessive foot external rotation in ankle dorsiflexion.
There are two main cited mechanisms for ankle syndesmosis injuries (Norkus & Floyd, 2001):
- ER of Foot on Tibia
- Hyper-dorsiflexion of the Ankle
Assessment and Diagnosis of Ankle Syndesmosis Injuries
The assessment and diagnosis of ankle syndesmosis injuries is one that requires careful integration of subjective, objective and radiographic information. Your assessment should not only diagnose but identify those who require surgery and exclude other differential diagnoses.
Athlete will often report:
- Mechanism: similar to that reported above
- Pain: anterolateral ankle pain, however, frequently “higher” than that of a lateral ankle sprain
- Observation: swelling seen proximal to ankle joint axis. Less prone to swelling than lateral ankle sprains given that the ligaments are extra-capsular (Fites et al., 2006).
- AROM: typically painful both saggital plane movements
- Palpation: tender on palpation of AITFL and PITFL (differentiate from lateral ligament complex). AITFL tenderness has a positive predictive value of 70% (Alonso et al., 1998). It has been noted that tenderness proximally along the interosseous membrane is indicative of more severe injury.
- Ottowa Ankle Rules: required to exclude possibility of a fracture.
- Ligament Testing: to exclude concomitant ligament injuries.
- Special Tests: the following special tests search for pain reproduction (not ligament laxity). The diagnostic accuracy of any is not well established.
Kleiger’s Test (DF/ER Stress Test)
Dorsiflexion Compression Test
X-Ray: radiological examination should include:
- Bilateral weight-bearing views
The diagnostic accuracy of x-rays has been questioned, showing poor sensitivity. False negative rates have been reportedly as high as 58% (Takao et al., 2003).
MRI: Has shown much greater diagnostic accuracy for identification of ligamentous injury. See table below:
Surgical management is indicated in the following cases (Williams & Allen, 2010; Mulligan, 2011):
- Frank Instability on Radiographs
- Presence of # requiring fixation
- Other surgically treatable pathologies (repairable syndesmotic ligament tear, latent instability, scarring or calcification of the syndesmosis)
In most other cases conservative management is indicated.
There are no hard and fast rules on rehabilitation time-frames. When conservatively managing ankle syndesmotic injuries progression of therapy is governed by symptomatic response (Mulligan, 2011). The conservative rehabilitation can be thought about in 3 phases:
Aims: Protection of healing tissues and control the initial inflammatory response.
- Protection: taping or boot
- Soft Tissue Massage (and effleurage for swelling)
- Manual Therapies: low grade talocrural, subtalar and tibio-fibular mobilisations
Aims: Regain ROM, strength and neuromuscular control
- Contrast thermal therapies
- AROM exercises
- PROM/PWB Stretches
- Gastrocnemius and other peri-articular ankle strengthening (e.g. 4 way thera-band)
- Don’t ignore proximal muscles e.g. hip
- Manual Therapies: higher grade mobilisations
- Progress to plyometric training
- Proprioceptive and neuromuscular exercises
- Increasing complexity of drills and training
- Agility skills
- High level balance training
- Plyometric drills
- Gradual and progressive return to team training
Again, there are no hard and fast return to play rules. However, widespread clinical experience is that AITFL or “high” ankle sprains have a longer recovery and rehabilitation period than lateral ankle sprains (Williams & Allen, 2010). As an overgeneralised rule; syndesmotic ankle sprains typically take 6 – 8 weeks to recover. Individually, Mulligan (2011) suggests that return to play decisions should be made through:
- Functional Tests: see here.
- Training Tolerances
- Objective Outcome Measures: such as the Foot and Ankle Disability Index
Photo Credit: Dplanet
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