- Exam:
- direct palpation: palpate for tenderness over the syndesmosis;
- squeeze test: at the mid-calf, squeeze the fibula against the tibia and look for symptoms at the syndesmosis;
- external rotation test: forced external rotation may cause pain at the syndesmosis;
- Radiographs:
- fibular fractures that begin proximal to tibial plafond are assumed to have some degree of injury of the syndesmosis;
- dorsiflexion and external rotation will accentuate syndesmotic widening;
-
mortise view:
- tibiofibular overlap: should normally be more than 1 mm;
-
lateral talar shift:
- tibio-fibular clear space:
- tibiofibular clear space> (interosseous clear space) is carilaginous space bewtween lateral border of posterior tibia (incisura fibularis) &
medial border of fibula, measured 1 cm above the joint line;
- normally the clear space is less than 5-6 mm on both AP and Mortise views;
- clear space of 10 mm is abnormal and indicates a syndesmotic injury;
- ap view
-
tibio-fibular clear space:
- tibiofibular clear space> (interosseous clear space) is the carilaginous space bewtween lateral border of posterior
tibia (incisura fibularis) & medial border of fibula, measured 1 cm above the joint line;
- normally the clear space is less than 5-6 mm on both AP and Mortise views;
- clear space of 10 mm is abnormal and indicates a syndesmotic injury;
- tibiofibular overlap:
- should be greater than 6 mm or 42% of fibular width;
- stress lateral view:
- correlates well w/ anatomic diastasis;
- is more sensitive than mortise view in determining syndesmotic injury;
- w/ a 7 mm anatomic diastatis, lateral malleolus may posteriorly displace 4-5 mm, where as mortise view shows only 1-2 mm of displacement;
The tibiofibular syndesmosis. Evaluation of the ligamentous structures,
methods of fixation, and radiographic assessment.
A radiographic evaluation of the tibiofibular syndesmosis. MC Harper, TS Keller. Foot Ankle Vol 10, 1989. p 156-160.
An anatomic and radiographic investigation of the tibiofibular clear space. MC Harper. Foot Ankle. Vol 14 v, 1993. p 455-458.
Ligamentous injury of the lower tibiofibular syndesmosis: Radiographic evidence. SJA Sclafani. Radiology. Vol 156, 1985. p 21-27.
The fibular incisure of the tibia on CT Scan. A cadaver study. NA Ebraheim. et al. Foot and Ankle Int. Vol 19. No 5. May 1998. p 318.
Technique tip: a revised method of the Cotton test for intra-operative evaluation of syndesmotic injuries.
Syndesmotic disruption in low fibular fractures associated with deltoid ligament injury.
Correlation of interosseous membrane tears to the level of the fibular fracture.
Radiographic Measurements Do Not Predict Syndesmotic Injury in Ankle Fractures: An MRI Study.
Intraoperative diagnosis of syndesmosis injuries in external rotation ankle fractures.
Syndesmotic instability in Weber B ankle fractures: a clinical evaluation.
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