Cuboid Syndrome (CS) is an easily misdiagnosed cause of pain in the lateral midfoot. CS is believed to arise from a subtle disruption of the arthrokinematics of the cuboid or issues with the calcaneocuboid joint not being structurally congruent, which irritates the joint capsule, ligaments, and peroneus longus tendon which passes underneath the cuboid.
CS accounts for around 4% of all foot injuries. Around 7% of inversion and plantarflexion ankle injuries will lead to CS. Ballet dancers are especially prone to CS which accounts for approximately 17% of all cases of ankle and foot pain in this group.
The cuboid is a stout, pyramid-shaped bone within the lateral midfoot and the lateral column of the foot. It articulates distally with the bases of the 4th and 5th metatarsals, medially with the lateral cuneiform and navicular, and posteriorly with the calcaneus (forming the calcaneocuboid joint). The principle movement of the calcaneocuboid joint is medial-lateral rotation about an anterior-posterior axis with the calcaneal process as a pivot. The cuboid can rotate as much as 25 degrees about this axis.
From the information above, it is clear that the calcaneocuboid joint is a very stable joint due to having multiple, congruent articulating surfaces, as well as having reinforcement from both ligaments and the peroneus longus tendon. The cuboid also acts as a pulley for the peroneus longus tendon while the tendon provides an eversion moment to the cuboid as it contracts from mid-stance to the late propulsive phase of gait. This is important, because the commonly held belief that CS is the result of subluxation or full dislocation of the cuboid may be difficult to prove, as anatomically it is a very stable joint. However, the cuboid does undergo compression forces which could disrupt the function of the calcaneocuboid joint complex and lead to pain. It is also possible that pain in this area could be due to the action of the peroneus longus tendon on the bone or injury to the tendon itself as it passes under the cuboid.
The two most common causes of CS are believed to be:
1. ankle inversion and plantarflexion injuries.
2. Accumulative loads higher than the tissue can tolerate without injury (sometimes called an “overuse injury”).
CS is more common in people with hypermobile and/or excessively pronated feet. It may also occur in people with pes cavus foot types.
Diagnosis is usually made by being examined in the clinic and by taking a history of the condition. Imaging is not believed to be helpful for diagnosing CS. Some have proposed using the midtarsal adduction and supination tests to diagnose CS.
Treatment involves using biomechanical assessments and orthoses to improve the overall function of the foot and reduce increased loads on the affected tissues. Acupuncture may be helpful to manage pain and inflammation. Therapeutic exercises, including proprioception exercises, are also prescribed. Steroid injections may be provided in difficult cases, and in cases that do not respond to conventional treatment, surgery may be recommended, although this is rarely needed.