The cuboid bone is a short bone in the lateral part of the foot, located on the distal row of the tarsal bones. It is square shaped, hence the name, and is the main bone of the mid foot, due to the several articular surfaces it possesses. Another key function of the cuboid is that it acts as a pulley to the peroneus longus tendon, which lies between the calcaneus proximally and the fourth and fifth metatarsals distally.
The cuboid articulates with four bones of the foot:
- the calcaneus posteriorly
- the lateral cuneiform medially
- the fourth metatarsal anteromedially
- the fifth metatarsal anterolaterally
On occasion there may be a fifth facet for articulation with the navicular, with research suggesting that this cubo-navicular joint occurs in a quarter of ‘normal’ feet. The likelihood of a cubo-navicular joint being present is increased in over-pronated feet.
To provide articulation with the calcaneus, the navicular has a large triangular proximal surface. The cuboid has a distal convex surface, with a medial quadrilateral facet for articulation with the fourth metatarsal, and a larger facet for articulation with the fifth metatarsal. There is a large oval facet medially for articulation with the lateral cuneiform. On the occasions where there is a navicular facet, it is small and oval, just behind the larger lateral cuneiform articulation.
The dorsal surface, directed upward and lateralward, is rough, for the attachment of ligaments.
The plantar surface presents in front a deep groove, the peroneal sulcus, which runs obliquely forward and medialward; it lodges the tendon of the peroneus longus, and is bounded behind by a prominent ridge, to which the long plantar ligament is attached.
The lateral surface presents a deep notch formed by the commencement of the peroneal sulcus.
The posterior surface is smooth, triangular, and concavo-convex, for articulation with the anterior surface of the calcaneus; its infero-medial angle projects backward as a process which underlies and supports the anterior end of the calcaneus.
The anterior surface, of smaller size, but also irregularly triangular, is divided by a vertical ridge into two facets: the medial, quadrilateral in form, which articulates with the fourth metatarsal and the lateral, larger and more triangular one, which articulates with the fifth metatarsal.
The medial surface is broad, irregularly quadrilateral, and presents at its middle and upper part a smooth oval facet, for articulation with the third cuneiform. Ocassionally, there is a smaller facet behind this for articulation with the navicular. The surface is rough in the rest of its extent, for the attachment of strong interosseous ligaments.
Deep branches of the medial and lateral plantar arteries (descending from the posterior tibial artery) supply the cuboid, with the deep venous arch providing venous drainage.
- Lateral plantar
- Deep fibular nerves
Cuboid syndrome is a commonly misdiagnosed lateral midfoot pain common in athletes. It is thought to arise from the disturbance of the articulatory surfaces and structural congruity of the calcaneocuboid joint.
Symptoms include pain resembling ligament sprain from the calcaneocuboid joint to the fourth and fifth metatarsal joints, sometimes radiating into the foot, with tenderness along the peroneus longus tendon. Cuboid syndrome is associated with several other foot problems, including:
- subluxed cuboid
- dropped cuboid
- locked cuboid
- peronial cuboid syndrome
- lateral plantar neuritis
Most of which affect the position and integrity of the cuboid bone.
Therapy includes manipulation of the cuboid bone with medial arch support. As with most syndromes of the foot, due to the delicate balance of the tarsals in relation to one another and the amount of force constantly applied to the area during walking and running, any slight dysfunction can easily onset pain and further problems.