Joints
Talocalcaneonavicular joint (art. talocalcaneonavicularis)
The head of the talus in a socket that is partly bone (navicular and calcaneus) and partly connective tissue: the plantar calcaneonavicular ligament, the spring ligament, forms its floor. Together with the posterior chamber, the subtalar joint, it carries inversion and eversion of the foot.
- Joint type
- Ball-and-socket joint with a composite socket, functionally one oblique axis
- Latin name
- Articulatio talocalcaneonavicularis
Movements, axes and normal values
| Movement | Plane | Axis | Normal range | End feel |
|---|---|---|---|---|
| Inversion | combined | oblique axis through the length of the foot | 20-30 degrees, measured together with the subtalar joint | firm springy (ligament) |
| Eversion | combined | oblique axis through the length of the foot | 10-15 degrees, measured together with the subtalar joint | firm springy (ligament) |
- Close-packed position
- Full supination
- Resting (loose-packed) position
- Midway between inversion and eversion
- Capsular pattern
- Supination of the forefoot on the hindfoot more limited than pronation; this part carries most of the midfoot motion, so a restriction shows up early.
- Arthrokinematics
- The talar head spins and glides in the socket while the forefoot follows; the axis runs obliquely from dorsomedial to plantarolateral. Because part of the socket is a ligament, the bearing surface changes with load: under load the head sinks slightly and tensions the spring ligament.
- Stability
- The plantar calcaneonavicular ligament, the interosseous talocalcaneal ligament and the tibialis posterior tendon passing beneath it as active support.
- Palpation
- The navicular tuberosity is the landmark: a finger's breadth distal to the medial malleolus and slightly plantar. From there the spring ligament runs to the calcaneus, and that ridge is tender in a collapsed arch.
- Clinical
- Insufficiency of the spring ligament, usually alongside tibialis posterior tendinopathy, produces an acquired flatfoot: the talar head drops medially and the heel drifts into valgus. Recognised by the too-many-toes sign and an inability to perform a single-leg heel raise.
- Source
- Speciële anatomie van het houdings- en bewegingsapparaat (HU, 2013); Reader anatomie in vivo (HU, 2020)