Cuboid bone

Role in foot anatomy

The human foot is a highly complex biomechanical complex. It consists of 28 bones that participate in the formation of over 40 joints. Anatomically, this skeletal apparatus is generally divided into three main segments:

• Rearfoot: includes the talus and calcaneus.
• Midfoot: this is precisely where the cuboid bone is located, adjacent to the navicular and cuneiform bones.
• Forefoot: consists of the metatarsal bones and phalanges of the toes.

Due to this multicomponent structure, the longitudinal and transverse arches of the foot are formed. Their main task is reliable stabilization and shock absorption under loads. This entire system allows for diverse movements: flexion, extension, adduction, abduction, as well as pronation and supination.

Participation in joint formation

Among the many articulations of the foot, two are of paramount importance: the tarsometatarsal joint (Lisfranc joint) and the transverse tarsal joint, better known in clinical practice as Chopart's joint.

The cuboid bone plays a critical role in the formation of Chopart's joint. This joint is formed by the proximal and distal rows of the tarsal bones. Specifically, the cuboid bone articulates with the calcaneus, forming the calcaneocuboid joint. Together with the talonavicular joint, it constitutes the line of Chopart. Understanding this anatomical boundary is extremely vital for diagnosing complex injuries of the midfoot.

Traumatology: fractures and dislocations

The epidemiology of lower extremity injuries shows that foot fractures account for up to 20% of all fractures. In clinical practice, fractures of the cuboid bone are distinguished alongside injuries to the talus, calcaneus, navicular, cuneiforms, metatarsals, and phalanges.

Of particular note are dislocations in Chopart's joint, which involve the dissociation of the calcaneocuboid and talonavicular articulations.

• Such an injury is quite rare.
• During dislocation, the distal part of the foot (including the cuboid bone) is displaced relative to the proximal part.
• The nature of the displacement can be twofold: dorsolaterally OR medially.
• The most frequently diagnosed injury in traumatology is dorsomedial dislocation.

Clinical significance of foot biomechanics

The cuboid bone, located in the center of the midfoot, is an integral part of the biomechanical chain. The functions of the foot (spring, balancing, and propulsive) are impossible without the proper anatomical interaction of all skeletal elements. Any disruption of integrity, whether a fracture of the cuboid bone or a dislocation in the calcaneocuboid joint, leads to impaired foot function.

The arches of the foot lose their shock-absorbing capacity, making normal weight-bearing impossible. Possible ranges of motion are severely restricted due to pain and deformity. To confirm the diagnosis and rule out concomitant fractures, radiography in two standard projections is mandatory.

Differential diagnosis of tarsal injuries

When examining a patient with a foot injury, the physician must keep in mind adjacent injuries of various segments. Although cuboid fractures have their own characteristics, they often need to be differentiated from other severe injuries:

1. Talar fractures: the most frequent in the rearfoot. Fractures of the neck and body of the talus significantly disrupt its blood supply, which frequently leads to the development of avascular necrosis.
2. Subtalar dislocations: occur under the influence of significant force (indirect mechanism). They are accompanied by pronounced deformity, where the foot is sharply shifted medially (supination and varus) or shortening of the forefoot is observed.
3. Chopart's dislocations: where the calcaneocuboid articulation is directly affected.

Class and exam questions

What else to study on this topic

• Talar fractures and the risk of avascular necrosis
• Mechanisms, clinical and radiological diagnosis of subtalar foot dislocations
• Technique of closed reduction of posteromedial dislocation and types of anesthesia
• Anatomy and injuries of the tarsometatarsal joint (Lisfranc joint)
• Pre-hospital care and immobilization principles in severe foot injuries

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.