1️⃣ Prevalence of DTFS Injuries
- Injuries to the distal tibiofibular syndesmosis (DTFS) are more frequent than previously believed.
- Previously estimated to represent 1%–18% of ligamentous ankle injuries, recent studies report an incidence of 17%–74% among sports-related ankle injuries.
- Syndesmotic injuries account for 18% of all lateral ankle sprains, with latent injuries being even less common.
- DTFS injuries may occur either in isolation or with an associated ankle fracture.
- Approximately 20.3% of ankle sprains have concomitant distal tibiofibular syndesmosis injury.
2️⃣ Clinical Suspicion in Chronic Syndesmotic Injuries
- Chronic syndesmotic rupture or malreduction should be suspected in patients with persistent pain and tenderness in the syndesmotic area following an ankle injury.
3️⃣ Challenges in Diagnosing Instability
- Frank Instability: Readily diagnosed on plain radiographs or computed tomography (CT).
- Latent Instability: More challenging to identify due to the absence of diastasis or incongruency on static imaging. Dynamic intraoperative testing during arthroscopy remains the gold standard for diagnosing latent syndesmotic instability.
4️⃣ MRI Findings and Diagnostic Features
✅ Lambda Sign:
Contiguous signal from the mortise into the syndesmosis on coronal PD FS sequences resembles the Greek letter lambda.
- This sign represents an injury to the interosseous ligament (IOL), allowing synovial fluid to travel from the mortise into the syndesmosis.
- The sign is considered positive regardless of the thickness or position of the contiguous signal in the sagittal plane.
✅ Distal Tibiofibular Joint Effusion (DTJE)
An 8-mm height of DTJE is identified as a more specific MRI indicator of distal tibiofibular syndesmosis instability (DTSI) and can serve as a novel diagnostic cutoff in clinical practice.
References
- J Orthop Surg (Hong Kong). 2023 May-Aug; 31(2):10225536231182349.
- Foot Ankle Int. 2014 Sep; 35(9):903-8.
- Skeletal Radiol. 2024 Feb; 53(2):329-338.
Hashtags
#DTFSInjury, #SyndesmosisInstability, #HighAnkleSprain, #SportsInjury, #ChronicInstability, #MRIFindings, #LambdaSign, #OrthopedicRadiology, #DynamicTesting, #RadiologyResearch
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