Syndesmodial Injury of the Lower Leg

By admin Last updated Nov 4, 2023

Ovid: 5-Minute Sports Medicine Consult, The

Delmas J. Bolin

Lauren Wood

Basics

Involves disruption of ligaments supporting the integrity of the mortise joint
Associated with prolonged symptoms of pain and dysfunction
Relevant injured structures can include anterior tibiofibular, posterior tibiofibular and transverse tibiofibular ligaments, interosseous membrane, and interosseous ligament, which serve to prevent lateral displacement of distal fibula during weight bearing
Synonym(s): High ankle sprain

Description

Mechanism of injury involves sudden, forceful external rotation of the dorsiflexed ankle.
The talus is pressed against the fibula, opening the distal tibiofibular articulation and rupturing the tibiofibular syndesmosis.

Epidemiology

10–20% of all ankle sprains
Higher percentage of ankle sprains involve the syndesmosis when occurring in collision sports such as football, rugby, and lacrosse.

Risk Factors

Collision sports are at higher risk:
- Football
- Rugby
- Lacrosse
Sports that immobilize the foot in a high ankle shoe or boot:
- Hockey
- Slalom skiing; catching inner ski on gate
Sports played on turf, eg, soccer

Commonly Associated Conditions

Deltoid ligament tear
Fibular or medial malleolar fracture
Heterotopic ossification or synchondrosis of the syndesmosis in 25–100% of cases
Tibiofibular synostosis resulting in prolonged pain and chronic disability
Longer healing time and more missed practices
Occult talar dome fracture

Diagnosis

History

Patient is often unable to adequately or completely describe mechanism; patients commonly report an inversion mechanism.
Focus history on mechanism of injury; raise index of suspicion with history of forceful external rotation, hyperdorsiflexion, or hyperplantarflexion.
Examples of common mechanisms include soccer (player tackling ball), football (player prone, has foot stepped on, leading to forceful external rotation), and skiing (slalom skiers, catch ski on gate)
Pain is usually between anterior distal tibia and fibula; also posteromedially at ankle joint.
Patients complain of pain with weight bearing, pushing off, or with external rotation.

Physical Exam

Less swelling than anticipated with severe lateral ankle sprain
Palpation of the tibia and fibula helpful to rule out fracture:
- Anterior joint line and anterior syndesmosis are often tender.
Squeeze test: Compression above mid-calf produces distal pain in the anterior ankle joint (syndesmosis).
External rotation test: Distal lower leg is stabilized with ankle in neutral position while mediolateral force/external rotation of the foot is performed. Positive test noted by pain and/or increased rotation relative to unaffected side.
Push-off test: Push-off/heel raise on affected side may be weak or absent.
Fibular translation (drawer) test: Increased translation of fibula from anterior to posterior or loss of firm end-point relative to uninjured side
Stabilization test: Distal syndesmosis is stabilized with athletic tape and assess if symptoms are decreased with running and jumping.
Cotton test: Increased translation or pain with translation of talus from medial to lateral (may indicate deltoid ligament tear)
Crossed-leg test: Pain at syndesmosis with gentle pressure exerted on the medial side of the knee while resting the mid-tibia of affected leg on uninjured knee
Evaluate distal neurovascular status with any lower leg injury to rule out acute compartment syndrome (1)[B].

Diagnostic Tests & Interpretation

Imaging

X-rays: Initial studies are static films. 50% of syndesmotic injuries have avulsion fractures associated:
- Weight-bearing anteroposterior view:
  - Tibiofibular clear space is among most sensitive indicators of syndesmotic injuries. Measured 1 cm proximal to ankle joint; widening demonstrated by >6 mm between medial border of fibula and medial cortical density of tibia.
  - Tibiofibular overlap; measured 1 cm proximal to joint; normal is >6 mm overlap between medial border of fibula and lateral border of tibia
  - Medial clear space should be <4 mm; >4 mm termed diastasis
- Standing mortise view to evaluate talocrural angle; the angle of a line drawn across tips of malleoli intersecting with a line perpendicular to a line drawn across the superior aspect of tibial plafond. Variation from contralateral side of >5° is significant.
- Lateral
Dynamic radiographs:
- Cotton test: Grasp distal fibula and pull laterally; modified cotton test: Push or pull fibula in sagittal plane. Comparison to contralateral side is frequently required.
- Varus and valgus ankle stress views are essential to assess instability.
- External rotation stress views not considered reliable indicators of syndesmotic injury

P.571

MRI can clarify diagnosis and extent of soft tissue injury:
- Compared with ankle arthroscopy, had sensitivity 100%/100% and specificity 93%/100% for anterior inferior/posterior inferior tibiofibular ligament disruption, respectively
CT helpful for bony detail of suspected talar dome injuries (2)[B].

Differential Diagnosis

Pronation-external rotation ankle fracture (Weber type C)
Supination-external rotation ankle fracture (Weber type B)
Fracture of the proximal fibula (Maisonneuve)
Ossification of the syndesmosis
Calcification of the syndesmosis
Deltoid ligament tear
Talar dome fracture
Tibiofibular synostosis resulting in prolonged pain and chronic disability

Treatment

Syndesmosis injuries without fracture (1)[B]: Consensus is 3–4-phase rehabilitation protocol. If no frank diastasis, most injuries result in inability to bear weight without symptoms.
- Phase I is to limit inflammatory response and protect the joint, usually with NSAIDs and short-term (10 days–2 wks) nonweight-bearing protection in a cast, boot, or brace with crutches. Include protection, rest, ice, compression, and elevation and modalities to minimize edema.
- Phase II is typically restoration of range of motion and normalization of gait pattern. In this phase, high ankle braces (Donjoy Velocity and others) may facilitate rehabilitation.
- Phase III progression once patient can ambulate and hop without dysfunction. Progress to agility drills, plyometrics, sports-specific tasks, and strengthening. Return to play when patient can demonstrate tasks such as backward pedaling, vertical hopping, or running in figure 8 pattern.
- Return to play is variable, usually 3–6 wks.
Syndesmosis injuries with fracture or diastasis noted on radiographs:
- Referral to orthopedic surgeon indicated if frank diastasis is noted on stress radiographs or if fracture is present.
Screw fixation followed by nonweight-bearing cast immobilization for 6 wks, followed by appropriate rehabilitation (1)[B].

References

1. Williams GN, Jones MH, Amendola A. Syndesmotic ankle sprains in athletes. Am J Sports Med. 2007;35:1197–207.

2. Herscovici D, Anglen JO, Archdeacon M, et al. Avoiding complications in the treatment of pronation-external rotation ankle fractures, syndesmotic injuries, and talar neck fractures. J Bone Joint Surg Am. 2008;90:898–908.

Additional Reading

Amendola A, Williams G, Foster D. Evidence-based approach to treatment of acute traumatic syndesmosis (high ankle) sprains. Sports Med Arthrosc. 2006;14:232–236.

Hopkinson WJ, St Pierre P, Ryan JB, et al. Syndesmosis sprains of the ankle. Foot Ankle. 1990;10:325–330.

Porter DA. Evaluation and Treatment of Ankle Syndesmosis Injuries. Instr Course Lect. 2009;58:575–581.

Codes

ICD9

845.03 Tibiofibular (ligament) sprain, distal

Clinical Pearls

A high ankle sprain involves ligaments that stabilize the ankle mortise joint. It is not a “routine ankle sprain” and must be treated differently.
High ankle sprains should be immobilized as soon as the diagnosis is made for a variable period ranging from a few days in elite professional and collegiate athletes to 2 wks for high school athletes. Suspect a high ankle sprain in a “regular ankle sprain” that is not improving as you expect.
Although there is little evidence for it, some have found high ankle stirrup braces helpful in the subacute setting for stabilizing the mortise joint, limiting rotational stress at the ankle, and permitting a more vigorous rehabilitation.