Joints
Ankle joint (talocrural joint)
The trochlea of the talus in the mortise of tibia and fibula. The trochlea is wider in front than behind, so the mortise has to give a little during dorsiflexion: the fibula moves cranially and rotates outwards with it.
- Joint type
- Hinge joint (ginglymus), one degree of freedom
- Latin name
- Articulatio talocruralis
Movements, axes and normal values
| Movement | Plane | Axis | Normal range | End feel |
|---|---|---|---|---|
| Dorsiflexion | sagittal | oblique through both malleoli, about 13 degrees to the frontal plane | 0-20 degrees with the knee extended | elastic (triceps surae) |
| Plantar flexion | sagittal | oblique through both malleoli | 0-50 degrees | elastic to hard |
- Close-packed position
- Maximal dorsiflexion, because the widest part of the talus is then in the mortise
- Resting (loose-packed) position
- 10 degrees of plantar flexion, midway between inversion and eversion
- Capsular pattern
- Plantar flexion more limited than dorsiflexion
- Arthrokinematics
- The convex trochlea of the talus moves in the concave mortise: roll and glide run in opposite directions. During dorsiflexion the talus rolls forward and glides backward. A restricted posterior glide is the most commonly missed cause of limited dorsiflexion after an ankle injury.
- Stability
- Laterally the anterior talofibular ligament (the first to be injured in an inversion trauma), the calcaneofibular ligament and the posterior talofibular ligament. Medially the strong deltoid ligament in four parts. The syndesmosis holds the mortise together.
- Palpation
- Lateral and medial malleolus, the joint line anteriorly between the tendons in slight plantar flexion, the anterior talofibular ligament as a band between the front edge of the lateral malleolus and the neck of the talus.
- Clinical
- Inversion trauma with injury of the anterior talofibular ligament, by far the most common sports injury; the Weber classification for fibular fractures; the Ottawa ankle rules determine whether a radiograph is needed; chronic ankle instability after repeated sprains.
- Source
- Kapandji, Physiologie articulaire deel 2; Magee, Orthopedic Physical Assessment; Ottawa ankle rules (Stiell et al.)
Clinical tests
- Anterior drawer test of the ankle
- Thompson test
- Ottawa ankle rules
- Talar tilt test
- Ankle fluctuation test