A cuboid is a cubic bone found on the outside of the foot in front of the heel. Its cuboidal body also contains a bony protrusion called the cuboid tuberosity that protrudes from the structure towards the sole of the foot.
The bone not only acts as a muscle attachment point and anatomical block, but also contributes to the mobility of the lateral (outer) spine of the foot.
Although cuboid fractures are rare, under certain circumstances they can occur infrequently. Also, subluxation (partial dislocation) of the calcaneo-cuboid joint can cause a rare but painful condition called cuboid syndrome.
The human foot is a complex but incredibly functional structure made up of 26 separate bones and 33 joints. The cuboid is one of the five that make up the midfoot , as well as the scaphoid, lateral, medial, and intermediate bones of the sphenoid. It is located on the outer edge of the foot and connects or articulates with five other bones in the foot.
Proximally (closer to the heel), the bone forms a joint with the heel bone and distally (closer to the toes) it meets the fourth and fifth metatarsals. As it moves towards the arch of the foot, the cuboid also fuses with the scaphoid and the lateral cuneiform.
The blood supply to this foot bone comes from the lateral plantar artery, a blood vessel that branches off from the posterior tibial artery .
Several different structures help to stabilize the cuboid in the middle of the lateral pillar of the foot. These include the calcaneal-cuboid ligament, the cuboid-navicular ligament, the cubovideo-metatarsal ligament, and the long plantar ligament.
The bone also has a muscular attachment. The tibialis posterior muscle extends from the lower leg and attaches to the lower or plantar surface of the cuboid bone .
The plantar and lateral surfaces of the bone also contain a major groove called the peroneal groove. This anatomical feature, through which the peroneus longus passes, provides a bony passageway for the tendon on its way to its attachment points on the first metatarsal and medial cuneiform .
The cuboid bone plays an important role in foot stability and daily work. Its only muscle accessory, the tibialis posterior muscle, helps to point or flex the foot downward .
This movement helps you propel yourself forward as you take a step. The muscle also helps to move the foot inward and supports the arch of the foot.
Also, the peroneus longus muscle, which traverses the fibular groove at the cuboid, twists or turns the foot outward. Muscle also helps guide the foot downward and plays an important role in our ability to balance.
However, perhaps the most important function of the cuboid is to provide stability and support to the lateral column of the foot. While the bone is not directly involved in loading, when standing and walking, a large amount of mechanical force is exerted on the cuboid body, which is dissipated .
This contribution also allows the outside of the foot to be more mobile and adaptable when walking on uneven surfaces.
Since it is in a fairly protected area of the foot and is not directly related to loading, the cuboid is not an area that is injured frequently. However, there are several conditions that can affect the bones.
One of the most common is cuboid syndrome. This condition occurs when the calcane-cuboid joint is subluxed and is usually caused by an ankle sprain or excessive repetitive pronation of the foot.
People with this syndrome often experience lateral foot pain (especially when walking), bruising, or swelling. They may also notice that the range of motion of the foot is more limited than usual .
Infrequently, the cuboid bone can also break. Although rare, it is usually the result of a heavy object falling onto the top of the foot and generally occurs in conjunction with a variety of other foot injuries. This type of fracture (sometimes called a nutcracker fracture) can also occur when the foot is excessively flexed and abducted (extended) .
Repetitive stress on the foot, such as forces associated with sports like endurance running, gymnastics, or basketball, can also lead to a cuboid stress fracture . This occurs when chronic stress on the side of the foot causes mechanical damage to the bone .
Regardless of the type of fracture, the symptoms closely mirror those seen in cuboid syndrome. The most common complaints are punctual tenderness over the bone, swelling, redness or bruising, and difficulty walking or playing sports.
In the case of cuboid syndrome, visualization is often irrelevant. Instead, the diagnosis is usually made after an exam in the healthcare provider's office.
This condition is usually treated conservatively with cuboid pads and physical therapy. The cuboidal manipulation technique can also be helpful in moving the bone after subluxation and reducing pain.
For cuboid fractures , an MRI can help to correctly visualize and diagnose the bone injury. This is especially true for stress fractures that are difficult to see on x-rays.
Once diagnosed, a cuboid fracture is usually also treated conservatively with a period of no stress on the body followed by a transition to walking shoes. Eventually, the wearing of the boots is stopped, and physical therapy begins to restore the foot's range of motion, regain strength, and help you get back into running or jumping.
Fortunately, the cuboid bone is rich in blood, so this type of foot fracture heals faster. However, infrequently, non-healing fractures or fractures that affect the length or function of the lateral spine of the foot may require surgical treatment.
In these situations, various techniques can be performed, including open reduction internal fixation, external fixation, bone graft, or joint fusion. Be sure to speak with your doctor if you've suffered a lateral foot injury so they can properly diagnose and treat your condition.