Consider the following presentations of athletes. A 35-year-old male ballet dancer presents to your office with an antalgic gait. He experienced sudden lateral foot pain in the left foot after making a slightly off-balance landing from a jump. He also complains of left foot weakness and fears that he may not be able to continue to dance ballet. A 14-year-old male basketball player comes in with acute lateral foot pain in his right foot. Currently on crutches, the player says the pain occurred two days ago after he landed on another player’s foot and twisted his ankle. A 22-year-old female ballet dancer complains of lateral foot pain that prevents her from rehearsing or performing regularly. She reports no history of trauma but a gradual onset of this pain, which persisted for two years in spite of treatment with physical therapy, nonsteroidal antiinflammatory medications and cortisone injections. What do all these athletes have in common? They all suffer from the same but poorly recognized condition: cuboid subluxation or cuboid syndrome. What Causes Cuboid Subluxation? While the inversion sprain is one of the most traumatic injuries to the lower extremity, a less recognized condition (and often a sequalae of an inversion stress at the ankle) is injury to the joints and ligaments around the tarsal cuboid, resulting in cuboid subluxation. Cuboid syndrome is a common cause of lateral foot pain in the athletic population and is often misdiagnosed or mistreated. It is usually defined as a minor disruption or subluxation of the structural integrity of the calcaneocuboid portion of the midtarsal joint. There are many synonyms for this condition including: lateral plantar neuritis, cuboid fault syndrome, dropped cuboid, locked cuboid and subluxed cuboid. An athlete with a cuboid subluxation will complain of lateral foot pain and weakness in push-off. The pain often radiates to the plantar aspect of the medial foot, the anterior ankle joint or distally along the fourth ray. This condition is common in ballet dancers and usually occurs acutely in male dancers when they land from jumps. Female dancers develop cuboid subluxation as an overuse syndrome from repetitive pointe work. Moving from foot flat to demi pointe initially creates a dorsiflexion moment on the midfoot, which changes to a plantarflexion moment while the foot moves to pointe. Again, the force reverses to a dorsiflexion moment while the foot returns to a flat position. The repetitive forces gradually decrease the stability of the midfoot and predispose some dancers to cuboid syndrome. The dancer will often complain of his or her inability to “work through the foot” while moving from this position of a flat foot to demi-pointe or a full point position. What One Should Look For In The Physical Exam When examining the affected foot of these patients, one can elicit pain by pressing dorsally on the plantar surface of the cuboid. Clinicians will find the cuboid’s minimal dorsal/plantar joint play is markedly reduced or absent when one compares it to the uninvolved foot. Severely subluxed cuboids can leave a shallow, visible depression on the dorsum of the cuboid and a fullness on the plantar aspect. Be aware that diagnosing cuboid syndrome via radiographs, computerized axial tomography (CT) scans or magnetic resonance imaging (MRI) is difficult because of the normal variations that exist between the cuboid and its surrounding structures, and the minimal amount of subluxation that is usually present. The term “locked cuboid” may more accurately describe this condition. As this term suggests, a small subluxation can markedly reduce the normal motion in the midtarsal joint, thus altering both the normal mechanics and the relationship between the rearfoot and the forefoot. The plantar displacement of the cuboid resulting in cuboid syndrome is most often reported in association with an inversion and plantarflexion stress of the ankle. It has been proposed that the mechanism of injury resulting in this isolated dislocation of the cuboid is due to rotation with associated inversion or eversion of the forefoot. The ligamentous disruption results in displacement of the cuboid. The peroneus longus tendon that travels in the groove on the inferior surface of the cuboid exerts a dorsal and lateral force on the forefoot. This rotational force would close pack the cuboid in its articulations and force the bone in an inferomedial direction, tearing interosseous ligaments. Another suggested mechanism is that the inversion stress at the ankle may cause a reflex contraction of the peroneus longus muscle in an attempt to restore balance and medial ground contact. This forceful contracture of the peroneus longus muscle creates a medial rotation of the cuboid. Then the peroneus longus tendon — within the osseous fibrous tunnel on the inferior surface of the cuboid — imparts a dorsal and lateral force on the cuboid, which results in the inferomedial subluxation. Disruption of the intertarsal ligaments may occur from the inversion force or when the cuboid is forcefully rotated. Other Conditions To Consider During Diagnosis There are many clinical conditions one must consider in the differential diagnosis of an athlete who presents with lateral foot pain (see “A Guide To Differential Diagnoses For Lateral Foot Pain” below). If the athlete is an adolescent, one should have a strong index of suspicion for tarsal coalition, a condition that is most similar to cuboid syndrome. Both can present with the same, non-specific symptoms that usually occur after a minor injury such as a mild ankle sprain. However, in the case of tarsal coalition, pain occurs in the subtalar or midtarsal area of the involved foot. It is aggravated by walking, prolonged standing, jumping or participating in athletics. Rest usually relieves the pain. In severe cases, the patient may present with an antalgic gait and have a significant limp. Upon examination, those with a tarsal coalition will usually have a stiff foot with a significant decrease in subtalar joint motion. In these cases, one will often note a loss of the longitudinal arch, hindfoot valgus and forefoot abduction. Forced inversion of the foot will exacerbate the symptoms. Radiographs may or may not be helpful in making a definitive diagnosis. (See “Is Peroneal Spastic Flatfoot Causing Chronic Ankle Pain?” in the June 2002 issue of Podiatry Today.) A Guide To Differential Diagnoses For Lateral Foot Pain Sinus tarsi syndrome Lateral process fracture of the talus Acute tendinitis of the peroneus longus tendon Fracture of the anterior process of the os calcis Malalignment of the lateral ankle and subtalar joints Fractures (including stress fractures) Meniscoid of the ankle Fracture or dislocation of the os peroneum Gout Inflammatory and noninflammatory arthritis Tarsal coalitions (in adolescents) Pertinent Pearls For Treating Cuboid Subluxation Once one has diagnosed cuboid syndrome, reducing the subluxed cuboid is the first step in the treatment process. Clinicians may employ a manipulative technique, which is often defined as a low-amplitude, high-velocity mobilization at the end of joint range, to restore proper joint congruency. However, be aware that there are contraindications to this manipulation technique. The contraindications include neoplastic or bone disease, inflammatory arthritis, gout and neural or vascular abnormalities. While facing the plantar surface of the patient’s foot, place your thumbs on the medial plantar surface of the cuboid with your fingers on the dorsal side. Doing so stabilizes the forefoot. Take care not to place the fingers directly over the cuboid on the dorsal side. Keeping the ankle joint in slight plantarflexion, apply a dorsally directed force to the medial side of the cuboid with a small amplitude, high-velocity thrust (see the photo at left). Often, the athlete experiences complete relief of symptoms with a successful reduction. One can then apply ice to the lateral side of the foot to reduce any inflammatory response and pain if necessary. Afterward, clinicians should use a cuboid pad in conjunction with a low-dye taping to maintain the cuboid reduction and give the arch added support. The cuboid pad is usually made of 1/4 inch felt. It is approximately 1.5 inches wide and 2 to 3 inches long. Ensure that the pad is skived at the edges for better fit and comfort. One can determine the actual length of the pad by measuring the distance from the calcaneocuboid articulation to the cuboid-fifth metatarsal articulation. Place the pad directly under the cuboid bone. It should not extend distally under the styloid process of the fifth metatarsal. Keep in mind that the cuboid pad may at times spontaneously adjust a mildly subluxed cuboid by its upward thrust. Further follow-up treatment may consist of placing a cuboid pad in the shoe, attaching one to a removable innersole or incorporating one into a foot orthosis. When placing this pad on a flexible orthosis, such as a leather laminate type of orthosis, you can place it on the bottom of the device. If the patient uses a more rigid orthosis, place the pad on the top. At this time, one should address other biomechanical abnormalities, such as a limb length discrepancy or ankle equinus. Patients may gradually return to sports activity when the pain subsides. Final Notes Keep in mind that cuboid subluxation following a second-degree or third-degree lateral foot sprain requires special care in order to prevent the development of a chronic condition. If one suspects a cuboid subluxation after a lateral foot sprain, do not attempt reduction until the effusion and ecchymosis have significantly diminished and you have ruled out the possibility of a fracture. When athletes present with ankle inversion sprains and complain of lateral foot pain, one should evaluate their cuboid articulations. Appropriate assessment and treatment of a subluxed cuboid is essential in order to restore normal joint range of motion, alleviate pain and improve foot function. Dr. Caselli (pictured) is a staff podiatrist at the VA Hudson Valley Health Care System in Montrose, N.Y. He is also an Adjunct Professor at the New York College of Podiatric Medicine and a Fellow of the American College of Sports Medicine. Dr. Pantelaras is a podiatric orthopedic resident at the VA Hudson Valley Health Care System in Montrose, N.Y.
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