Joints
Distal tibiofibular syndesmosis (syndesmosis tibiofibularis)
The fibrous connection between the fibular notch of the tibia and the distal end of the fibula. It holds the ankle mortise together; the talus is clamped between its jaws, and that clamp has to be firm yet yield a few millimetres.
- Joint type
- Syndesmosis (fibrous joint), no cartilage and no capsule
- Latin name
- Syndesmosis tibiofibularis
Movements, axes and normal values
| Movement | Plane | Axis | Normal range | End feel |
|---|---|---|---|---|
| Widening of the mortise | frontal | sagittal (anteroposterior) | 1-2 mm in full dorsiflexion, as the wider anterior part of the talar trochlea rotates in | firm springy (ligament) |
| Translation | sagittal | transverse (mediolateral) | a few millimetres of proximal and posterior travel of the fibula | firm springy (ligament) |
- Close-packed position
- Maximal dorsiflexion
- Resting (loose-packed) position
- Slight plantar flexion
- Capsular pattern
- No capsule, so no capsular pattern; pain on squeezing the mortise apart and on rotation of the foot.
- Arthrokinematics
- In dorsiflexion the fibula moves laterally, rotates outward and travels slightly proximally. Without that accessory motion the last degrees of dorsiflexion are lost, and clinically that limits a squat more often than the talocrural joint itself.
- Stability
- The anterior and posterior tibiofibular ligaments, the transverse ligament and the interosseous membrane running all the way up to the knee.
- Palpation
- The anterior tibiofibular ligament runs obliquely across the front of the mortise, a finger's breadth above the lateral malleolus. Pressure there hurts in a high ankle sprain while the lateral ligaments are clean.
- Clinical
- The high ankle sprain: syndesmotic injury from forced external rotation with dorsiflexion, common in field sports. Recovers considerably more slowly than a lateral ligament sprain, and is missed if you palpate laterally only. The squeeze test and external rotation test point to it.
- Source
- Speciële anatomie van het houdings- en bewegingsapparaat (HU, 2013); Magee, Orthopedic Physical Assessment