Overview
The tibia is the medial, weight-bearing bone of the leg; the fibula runs alongside it laterally. In the cat it is long and slender, with a shaft covered by little muscle on its medial surface, where it can be felt directly under the skin.
Proximal end
- Medial and lateral condyles: articular surfaces for the femoral condyles, separated by the intercondylar eminence; the menisci rest on them.
- Tibial tuberosity: insertion of the patellar ligament; it continues distally as the cranial border.
- Articular surface for the fibula: on the caudolateral side of the lateral condyle.
Shaft
Triangular proximally and more cylindrical distally. Its medial surface is subcutaneous; the lateral surface is covered by the tibialis cranialis muscle.
Distal end
- Cochlea of the tibia (cochlea tibiae): grooved articular surface that fits the trochlea of the talus.
- Medial malleolus: palpable projection on the medial side of the tarsus, origin of the medial collateral ligament.
Clinical relevance
- Tibial fractures: common in cats; because the medial surface has hardly any muscle cover, many are open. They are usually treated with plates or external fixators.
- Cranial cruciate ligament rupture: in the cat it usually affects overweight animals, often without clear trauma, and frequently comes with meniscal injury.
- Meniscal ossicle: a small mineralisation in the medial meniscus is a normal finding on feline stifle radiographs and must not be mistaken for a fragment.
- Patellar luxation: may come with rotation of the tibial tuberosity.
- Osteosarcoma: the proximal tibia is one of the appendicular sites in the cat.