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Cuboid Subluxation: A Case Study and Review of the Literature

Adams, Erik; Madden, Chris

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doi: 10.1249/JSR.0b013e3181c1b939
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Abstract

INTRODUCTION

Cuboid subluxation may be defined as a minor disruption or subluxation of the structural congruity of the cuboid articulations, particularly the calcaneocuboid joint, resulting in pain and impaired joint function (2,8,10,12). Irritation or inflammation of surrounding joint capsules, ligaments, and the peroneus longus tendon may contribute to symptoms of lateral midfoot or lateral column pain and weakness during push off. Various mechanisms of injury and types of cuboid subluxations have been suggested. Suffering from a primarily anecdotal existence, cuboid subluxation operates under the guise of various names, including cuboid syndrome, locked cuboid, dropped cuboid, cuboid fault syndrome, and peroneal cuboid syndrome. Cuboid subluxation or syndrome also is characterized in the literature as common, uncommon, poorly understood, clinically unproven, misdiagnosed, underdiagnosed, unrecognized, and mistreated (8,10,12). The lack of consensus among physicians regarding this entity invites confusion in the diagnosis and management of cuboid subluxation, which primarily rests in a proper history and physical examination, leading to an accurate clinical diagnosis and conservative treatment that usually involves manipulation, relative rest, physical therapy, and sometimes external supports such as orthotics, taping, or a pad (1,2,5,8,10,12). Traditional diagnostic imaging does not offer much help establishing the diagnosis, but ultrasound may offer an opportunity to improve diagnostic accuracy, both by static imaging of ligament injury and intraarticular effusion, and by dynamic study of joint motion. The following case report presents unique considerations with cuboid injury, but primarily serves as a springboard to discuss more broadly the underrepresented topic of cuboid subluxation.

CASE REPORT

History

An 11-yr-old girl injured her left foot in school gym class 3 wk before she was supposed to perform in a holiday ballet production. Her skill level at the time in ballet was demi-pointe. She was injured while running to catch a ball and inverted her foot off the edge of a curb. She experienced immediate pain localized to the lateral midfoot, and she had difficulty weightbearing. She had complained in the previous few months of nonlocalizing foot pain after dance class, but the pain was mild enough to permit full participation in ballet and jazz dance rehearsals. She had experienced bilateral calcaneal stress reactions 8 months before her current injury, and there was no prior history of acute foot or ankle injury.

Physical Examination

Physical examination 4 h after the injury revealed a severely antalgic gait, favoring the left foot, with swelling noted over the dorsum of the left cuboid. She had a loss of 30° of plantar flexion and 10° of dorsiflexion at the ankle joint, and subtalar inversion and forefoot adduction were especially painful and guarded. Palpation revealed intense tenderness at the plantar surface of the cuboid, particularly with any attempt to assess dorsal/plantar motion of the cuboid. The dorsal calcaneocuboid ligament was likewise tender, with a lesser degree of tenderness noted at the cuboid-fourth metatarsal articulation. There was minimal tenderness of the anterior talofibular ligament and none at the deltoid or calcaneofibular ligaments. There was swelling over the dorsal calcaneocuboid joint, but none on the plantar aspect of the foot; no depression was noted at the dorsal aspect of the calcaneocuboid joint. Anterior drawer stability was symmetrical to the uninjured ankle. The patient did not tolerate talar tilt testing. The neurovascular exam was normal.

Diagnostic Imaging

An oblique plain radiograph is shown in Figure 1. No fracture is identified; calcaneocuboid joint widening is seen on this oblique view, as well as on the anterior posterior (AP) and lateral views.

Figure 1
Figure 1:
Oblique plain radiograph of injured left foot.

Ultrasound exam revealed an effusion with echogenic debris at the dorsal aspect of the left calcaneocuboid joint (CCJ). With the ankle in a neutral position, the cuboid was shown to be displaced in a plantar direction, compared with the position of the lateral articular surface of the calcaneus (Fig. 2). The calcaneocuboid step-off was measured at 0.25 mm with the ankle neutrally positioned, compared with 0.11 mm on the uninjured side. Follow-up sonographic imaging demonstrated no improvement in the step-off after 2 wk of casting, but then revealed gradual improvement on serial exams. At 5 wk postinjury, the step-off was within 0.5 mm of the uninjured side, at which time weightbearing was permitted, as well as limited participation in dance, which possibly resulted in worsening of the initial traumatic laxity. After approaching normal at 3 wk, dorsoplantar stress at 5 wk postinjury showed increased motion compared with the uninjured side. At 19 wk postinjury, a 0.2-cm step-off at the left CCJ remained, noted with the ankle at its limit of dorsiflexion, compared with a congruent joint on the right. Comparison of the step-off between dorsiflexed ankles proved to be the greatest and longest lasting abnormality (Table 1). No literature guidelines exist for the sonographic evaluation of CCJ stability. Step-off at the CCJ with the ankle in a neutral position initially was used, along with dynamic imaging of dorsoplantar stress, but as the case progressed, failure of the injured CCJ to assume congruency in dorsiflexion became more apparent. Both the injured and uninjured joints showed plantar motion of the cuboid to approximately the same extent with end range plantar flexion, but only the injured side showed incongruency in dorsiflexion. This abnormality might be viewed as a failure of the joint to resume its normal position upon removal of a plantar flexion stress, likely caused by a still-incompetent dorsal calcaneocuboid ligament. As the patient grows and matures, we hope that the injured ligaments will be restored to their normal length-tension relationships and that joint congruency likewise will be restored. Stability of this joint appears to be necessary for successful en pointe weightbearing in ballet.

Figure 2
Figure 2:
Ultrasound image, left calcaneocuboid joint, axial view.
TABLE 1
TABLE 1:
Ultrasound measurement of left calcaneocuboid joint congruency during recovery.

Diagnosis and Treatment

The patient was diagnosed with a grade II sprain of the left dorsal calcaneocuboid ligament, with plantar subluxation of the cuboid at the CCJ based on history, provocation of pain during examination, and ultrasound findings. On the day of the injury, gentle reduction of the subluxation was attempted but was lost as soon as pressure was discontinued. The patient was placed in a short-leg fiberglass cast 1 d postinjury, with the ankle in neutral position. The cast was well-formed at the plantar aspect of the cuboid to reduce its plantar subluxation, and a window was cut in the cast over the dorsal aspect of the CCJ to allow ultrasound imaging of the joint. This molding technique resembled the cuboid squeeze maneuver used by Marshall and Hamilton (8), except with a neutral ankle position. The cast was changed at 2 wk and again was molded to reduce the subluxation. Before changing the first cast, which had loosened because of a decrease in swelling, ultrasound examination through the cast window showed partial loss of initial reduction. The patient was partially compliant with non-weightbearing instructions through 3 wk, at which time reexamination revealed only minimal tenderness with plantar pressure on the cuboid and gait was antalgic only minimally. She was permitted to dance in dress rehearsals and performances, participating in the pieces that did not require unilateral relevé on her injured side, but she continued partial weightbearing using crutches during all non-dance activities. She was observed to limp after one of these pieces on the last performance day and complained of increased pain for the next week. The patient then was placed in an ankle stabilizing orthosis (ASO) ankle stabilizer brace with a felt pad taped under the plantar surface of the cuboid. This approach is similar to that used by Marshall and Hamilton (8), in which taping and a felt pad were used. Non-weightbearing was again prescribed, and she was weaned off crutches after an additional 3 wk. Two months postinjury, a total of 3 h of dancing each week was allowed, without relevé nor jumping. Three months postinjury, she was able to relevé on the affected foot, and 4 months postinjury, she was able to land painlessly from a jump with proper form on the affected side.

DISCUSSION

Incidence

There is a paucity of reports of cuboid subluxation in the literature. However, cuboid subluxation appears to be a fairly common malady in ballet dancers and may be relatively common in other athletes as well. In a report by Marshall and Hamilton in 1992, cuboid-related problems comprised 17% of all foot and ankle injuries in the American Ballet Theater (8). Their series found that cuboid subluxation was more common in female dancers, generally resulting from overuse situations, particularly with pointe work. Over a 3-wk period of rehearsal and performance with a premiere ballet company, Marshall and Hamilton saw 63 ankle and foot injuries requiring physical therapy, 11 (17%) of which were cuboid-related (8).

In contrast, Newell and Woodle reviewed 3600 foot injuries in athletes of all types and found that only 4% were cuboid-related (11). Jennings and Davies, who specialized in diagnosing and treating cuboid syndrome, diagnosed cuboid syndrome in only 6.7% of their patients who presented with an inversion-plantar flexion sprain (5).

In general, the midfoot joints appear to be vulnerable to injury in ballet dancers. Ménéntrey and Fritschy reported a series of 25 cases of subtalar subluxation in a company of 60 dancers, over a 1-yr period (9). Injury appears to have been related to the introduction of a new teacher who required more than the usual amount of jumping en pointe and demi-pointe (see sidebar for description of positions). One dancer subluxated abruptly upon entering a grand plié on demi-pointes.

Figure
Figure

Distinguishing Case Features

The injury described in our case report likely involves more soft tissue trauma than traditional subluxations, specifically affecting a localized area over the dorsal calcaneocuboid joint. Many reductions are associated with an audible clunk and relief of symptoms, but in the case patient, the cuboid was not wedged into a subluxated position; rather, it appears to have drifted out of position from disruption of the dorsal calcaneocuboid ligament. Maintenance of reduction was unsuccessful, likely because of partial ligamentous disruption, and the patient was casted to support the injured ligament so it would heal in a shortened, anatomic position. Immobilization was longer than with less significant acute injuries, and return to activity was more prolonged. Ultrasound examination provided unique diagnostic insight, both with initial diagnosis and subsequently during return to dancing.

Anatomical Considerations

The cuboid is the Atlas of the lateral midfoot, unique in its sole position as the pillar of the lateral column, the only lateral mediator of force transfer between the hindfoot and the forefoot. Any disruption of cuboid position likely affects midtarsal motion and alters normal mechanics between the forefoot and the hindfoot (3,8). Sellar-shaped synovial joints border the cuboid posteriorly with the calcaneus and anteriorly with the fourth and fifth metatarsals. The cuboid articulates with the lateral cuneiform and the navicular medially, forming an obliquely-, inferomedially-oriented joint (10). Gliding and rotation are the primary motions of the cuboid articulations. These motions are embedded within the two primary combined movements of the lateral functional unit of the foot: 1) plantar flexion, adduction, and inversion, and 2) dorsiflexion, abduction, and eversion. Laterally and inferiorly, the peroneus longus tendon slings the cuboid as it dives into a fibro-osseous tunnel on the plantar aspect of the cuboid, exerting a dorsal and lateral force on the foot, with the cuboid serving as its fulcrum (10). Forceful contraction of the peroneus longus or tightening of the tendon passively during forceful foot plantar flexion, inversion, and adduction forces the cuboid into its close-packed position, and sometimes beyond, resulting in plantar medial displacement.

In the uninjured dancer's foot, entry into the en pointe position initially causes a dorsiflexion moment at the tarsometatarsal (TMT) articulations. Upon reaching full ankle plantar flexion, if the dancer's balance carries her further, an opposite plantar flexion moment is experienced at the TMT joints. Repetition of these forces during dance destabilizes the midfoot, predisposing a dancer to cuboid subluxation (8).

Etiology

Mechanisms of injury are acute, traumatic, and chronic, as well as overuse (8,10,12).

Plantar flexion and inversion ankle sprains account for most traumatic cuboid subluxations (5,10,12). Marshall and Hamilton also describe a traumatic cause of subluxation primarily affecting male dancers that involves landing from a big jump, or a series of big jumps, such as in a bravura variation, with resultant forceful foot pronation. Subluxation also can occur after a lateral midfoot sprain. All mechanisms may involve a forceful reflex contraction of the peroneus longus muscle with resultant injury of the pericuboid ligaments.

Overuse injury to the cuboid articulations occurs with repetitive microtrauma, resulting in dorsal ligamentous laxity and hypermobility, more common in female ballet dancers (8).

Risk factors for subluxation are variable and may include mechanical or functional ankle instability, ballet dancing, acute lateral ankle or foot sprains, peroneal tendon pathology, excessive pes planus or cavus, ligamentous hypermobility, improperly constructed orthotics, uneven running terrain, and prior heel spur surgery (8,10,12).

Cuboid subluxations can be plantar or dorsal. Plantar subluxations account for the vast majority of subluxations reported in the literature and involve inferomedial displacement of the cuboid. Most reduction maneuvers described target this type of injury. Dorsal subluxations are rare (10). The fourth and fifth metatarsals also can subluxate dorsally on the cuboid.

History and Physical Examination

Cuboid subluxation presents variably to the examiner. Pain complaints range from specific, localizing discomfort over the cuboid, particularly plantar, to more vague lateral column foot pain. Pain onset can be sudden with acute injuries or more insidious, after and sometimes during, provocative activities. Pain may radiate into the medial plantar arch, distally toward the fourth and fifth metatarsals, and proximally toward the ankle (8,12). Patients may complain of weakness during the toe off or push off phases of gait, especially with higher impact activities. Dancers may be unable to jump or land from a jump, relevé, or perform en pointe. Moving from foot flat to demi-pointe or pointe may be particularly difficult. Sometimes pain may occur with walking or even at rest.

Physical examination findings of cuboid subluxation are variable, and there is no pathognomonic test to establish the diagnosis, which often reveals itself in a suspicious history consisting of an appropriate mechanism, cuboid area pain, and history of participation in provocative activities. A supporting examination may involve subtle cuboid displacement or reproducible pain with one or more provocative tests. Examination of an athlete after the specific symptom-inducing activity can aid in accurate diagnosis.

The examiner should inspect the foot for mechanical faults, both statically and dynamically, and observe any alteration in gait. Physical examination likely will reveal palpable discomfort over the cuboid, its surrounding articulations, and occasionally over the distal peroneus longus tendon. Fullness sometimes is appreciated over the plantar surface of the cuboid. With a more significant subluxation, a dorsal depression may be observed over the dorsal lateral midfoot. More significant trauma resulting in swelling, effusion, and ecchymosis can make it difficult to assess cuboid motion mechanics and subtle malposition. Subacute and chronic injuries may be associated with more subtle, boggy swelling over the cuboid and its articulations.

Normal active and passive range of motion at the foot and ankle may be decreased (8,10). If cuboid displacement is not obvious with initial inspection and palpation, careful assessment of accessory joint glides and passive physiological motion tests will help identify altered joint motion and direction of subluxation (10). Passive physiological mobility and joint glide of the lateral functional unit of the foot are assessed in combined plantar flexion, adduction, and inversion (supination), and also in dorsiflexion, abduction, and eversion (pronation), which are decreased in plantar and dorsal cuboid subluxation, respectively. Reproduction of familiar pain with manual provocative testing also raises suspicion for subluxation, and may be more helpful if subtle motion abnormalities are not obviously apparent. Accessory plantar and dorsal glides may reveal decreased joint glide, but also can identify laxity, evidenced by increased glide if the cuboid is not subluxated at the time of the exam (10). Plantar subluxations result in decreased dorsal glide, whereas less common dorsal subluxations are identified by decreased plantar glide. After acute injury, the patient also may not tolerate an adequate exam of joint mobility, and care must be taken to avoid examination forces that may further damage injured ligaments.

Additional physical exam maneuvers raise suspicion for cuboid subluxation, particularly plantar subluxation. Both passive inversion and active plantar flexion and eversion may cause familiar pain (2,10,11). Pain along the distal peroneus longus tendon as it passes beneath the cuboid may be elicited with resisted active eversion or passive inversion (13).

Radiologic Evaluation

Radiographic, computed axial tomography, and magnetic resonance imaging studies generally are unhelpful in establishing the diagnosis of cuboid subluxation, probably because of variations in the normal anatomy of the cuboid and surrounding structures and the minimal displacement of the subluxated cuboid. However, a report by Everson et al. illustrates two patients with cuboid subluxation whose plain films demonstrated a plantar flexed position of the cuboid and an abnormal calcaneocuboid joint space (4). They assert that the appropriate amount of joint space around the cuboid is 2 mm. The CCJ space in our case report measures 4 mm on the lateral radiograph. These diagnostic imaging studies are helpful primarily for excluding other pathology such as fracture or fracture-dislocation (4).

Ultrasound evaluation may hold promise for significant, traumatic cuboid or midfoot injuries. Serial ultrasound imaging of the injured CCJ in the case report patient demonstrated that the most enduring abnormality was joint incongruency with the ankle in a dorsiflexed position. Eight weeks postinjury, the amount of step-off at the injured CCJ with the ankle plantar flexed was equivalent to the contralateral side, but the joint did not demonstrate normal congruency with the ankle completely dorsiflexed. Congruency in a neutral ankle position was restored by 3 wk with molded casting, but the CCJ likely was not stable enough to maintain the reduction during weightbearing activities because subsequent ultrasound imaging showed less congruity. The asymmetrical, abnormal joint congruency observed in dorsiflexion persisted until 19 wk postinjury, despite resolution of symptoms.

Musculoskeletal ultrasound offers an opportunity to confirm the diagnosis and assess the adequacy of reduction, in addition to assessing the possibility of other soft tissue injuries such as peroneal tendon pathology (1). Comparison always should be made with the asymptomatic side when determining appropriate joint congruency and motion. Findings such as joint effusion, debris within the joint, and excessive joint step-off at rest are useful diagnostic clues. Ultrasound also allows precise confirmation of which anatomical structures are tender using a technique that involves placing a paper clip between the ultrasound probe and skin, at a right angle to the probe orientation so that its shadow falls over an anatomical structure of interest. Pressing the paper clip into the skin briefly leaves a faint indentation, and upon removal of the probe and paper clip, this area is palpated. Palpation can be carried out with a pencil eraser or retracted pen tip to help localize affected structures.

Detecting joint instability by dynamic ultrasound largely is a qualitative process. In an attempt to obtain quantitative data, the examiner can measure and compare joint distraction distances at end ranges of motion in still images, but it is essential that exactly the same view be used for all comparisons. The curvature of the cuboid and the three-dimensional nature of its motion made this process difficult in our case. CCJ step-off varied, depending on the relative contributions of plantar flexion and forefoot adduction. Additionally, step-off depended on the exact location of the ultrasound probe placed over the CCJ. Joint congruity also varied with ankle position. Ankle plantar flexion caused the cuboid to move in a plantar direction relative to the distal calcaneus, on both the injured and uninjured sides. As the patient recovered, it was found that the most persistent abnormality was a failure of the CCJ to assume congruency as with ankle dorsiflexion. One must be aware that there likely is a small amount of normal motion at the calcaneocuboid joint during functional weightbearing activities, and that comparison studies will need to be performed carefully to determine asymmetry (8).

Other joints, especially those with more obvious anatomical landmarks and uniplanar motion (e.g., the medial collateral ligament of the knee) should be less difficult to image with ultrasound. In any case, the clinician must resist the temptation to rely entirely on the ultrasound for clinical evaluation. In addition to imaging, changes in pain level, ability to perform a functional progression, and manual testing of joint stability are essential components of assessment during recovery.

Differential Diagnosis

The differential diagnosis of lateral midfoot or lateral column pain is broad, but it can be narrowed with a careful history, physical examination, and occasional, appropriate diagnostic imaging. Considerations of lateral midfoot pain are listed in Table 2 (6,7,10,12).

TABLE 2
TABLE 2:
Causes of lateral midfoot pain.

Management

Appropriate assessment and treatment of cuboid subluxation aims to restore normal joint motion, improve function, and alleviate pain (10). Acute, subacute, and chronic injuries may require different treatments and often have variable recovery times, depending on the extent and chronicity of the injury. Management may include manipulation or mobilization, relative rest, activity modification, physical therapy (arch and midfoot strengthening), external dynamic support, and occasional immobilization.

Manipulation usually is appropriate for most acute and chronic injuries, but physicians must be careful when manipulating or referring for manipulation more significant acute, traumatic injuries, especially injuries associated with impressive swelling and ecchymosis, to avoid further injury to damaged ligaments, and less commonly, bone. Less significant acute and subacute injuries involving subluxation without extensive soft tissue findings respond well to manipulation, which may need to be repeated a few times over subsequent days to weeks. Chronic injuries may or may not respond well to manipulation, and repeat manipulations with the occasional need for self-manipulation are often needed to return the cuboid to its proper position. Whether subluxation is plantar or dorsal, reduction can be accomplished more effectively with adequate distraction of the cuboid articulations (8).

Various maneuvers have been described to reduce a plantar and medially subluxated cuboid. Perhaps the safest and easiest reduction maneuver is the cuboid squeeze (Fig. 3). The cuboid squeeze is performed with the patient prone and the foot and ankle in maximum plantar flexion. The examiner elicits a subtle axial distraction force with both hands while gently pressing the plantar cuboid in the dorsal and lateral direction or "squeezing" it in a controlled fashion between the examiner's overlapping thumbs (over plantar cuboid) and fingers (crossed over the dorsum of the foot), which also serves to gently massage dorsal extensors and peronei to get them to relax. An alternative method involves the examiner eliciting an axial distraction force with one hand while gently squeezing the cuboid from its plantar aspect with the other. Pressure is applied on the plantar aspect of the cuboid with the thumb of one hand, while the fingers of the same hand stabilize the tissues surrounding the dorsal aspect of the cuboid.

Figure 3
Figure 3:
Cuboid squeeze.

The cuboid whip (Fig. 4), first described in 1981 by Newell and Woodle (11), is another standard technique for reducing subluxation, although the term "whip" may be inappropriate because it implies a whipping of the foot, which can transmit significant force to the talocrural joint and other surrounding structures, potentially resulting in other injury if forces are too great. The technique may be performed with the athlete lying or standing. The standing position has been described as the horseshoeing position because the athlete stands on the unaffected leg with the affected foot 'hanging" freely in the air, and the knee is bent in approximately 90° of flexion while the examiner stoops over or sits on the floor behind the foot. The lying position offers two alternatives, one with the athlete lying prone with hip neutral and knee flexed at approximately 90°, and the second with the athlete lying supine with both the hip and knee in approximately 90° of flexion. All manipulations are performed by interlocking the fingers over the dorsum of the foot to act as a fulcrum, positioning the thumbs side by side or overlapping over the plantar cuboid (over prominence if obvious), starting with ankle neutral position, then gently "swinging" the ankle, foot, and knee through a small, fluid arc of sagittal plane motion. When guarding is minimal and the extensors and peronei are relaxed, the examiner exerts a dorsally and laterally directed brief, high-velocity, low-amplitude force to the plantar cuboid prominence while the ankle gently swings into the plantar flexion phase of the swing. Sometimes an audible pop or clunk is appreciated.

Figure 4
Figure 4:
Cuboid whip.

Manipulation usually is effective for acute and subacute plantar subluxations. Newell and Woodle propose that a cuboid subluxation present for 1 wk or less may require only one to two manipulations (8,11). Symptoms present for a month are reported to respond to two to four manipulations (11). Symptoms present for 6 months will likely demand repeat evaluation and manipulation over a period of 6 months or more (5). Cuboid position and lateral column motion and function should be reassessed after each manipulation.

Dorsal subluxations are addressed with two alternative techniques. The first involves the examiner "hanging" a supine athlete's foot by grasping the fourth metatarsal between fingers and thumbs and allowing gravity and the weight of the leg and foot to help distract the cuboid-fourth metatarsal joint (Fig. 5). The fourth metatarsal is pulled longitudinally with the forefoot in slight plantar flexion. This technique requires complete relaxation of the leg and foot muscles, and it also may be used to address dorsal subluxations of the base of the fourth metatarsal, a less common injury (8). Dorsal subluxations also may be reduced by having the patient, who is seated on the floor, grasp and stabilize his or her distal fibula and tibia while the examiner applies traction to the fourth and fifth metatarsals with one hand while the other hand applies a plantar thrust to the dorsal surface of the cuboid with the foot flat on the floor (Fig. 6) (10). An audible clunk may accompany acute or subacute relief of pain.

Figure 5
Figure 5:
Manipulation of dorsal cuboid subluxation.
Figure 6
Figure 6:
Manipulation for a dorsal cuboid subluxation.

Cuboid reductions may hold without external support, but if athletes resubluxate after initial reduction, support should be considered, and some physicians opt to support the cuboid for a short period of time after initial reduction. Ice may be applied to minimize swelling. With acute traumatic injuries associated with minimal to no laxity, brief immobilization for a week or two in a short-leg pneumatic walker boot, combined with a full-length, supportive foot orthotic and arch taping (which authors prefer over an arch strap), may help maintain proper cuboid positioning and facilitate healing of surrounding soft tissues. More significant traumatic injuries associated with laxity may require more prolonged immobilization. A small dense foam or Nickelplast pad shaped and skived (with grinder) to the plantar surface of the foot over the cuboid may be attached to the topcover or beneath a softer or semi-rigid orthotic using contact cement or double-sided tape. Pads may be helpful with or without immobilization and can be augmented with cuboid taping (Fig. 7) and/or bracing with a corset-type or wraparound ankle brace that extends over the midfoot such as an ASO. External support with bracing, taping, and/or a cuboid pad should be applied until a few weeks after the athlete is asymptomatic and initially during activity progression. The supports may be discontinued if athletes remain symptom-free after returning to full activity.

Figure 7
Figure 7:
Cuboid subluxation taping. Begin taping medially (top left), then strap cuboid laterally (top right) - a small cuboid pad may be secured between the tape and cuboid where the examiner's finger is pictured above. Final taping is pictured bottom right.

Foot and ankle strengthening exercises should be started as early as can be tolerated pain-free. Physical therapy should focus on strengthening the intrinsic and extrinsic muscles of the foot and the ankle stabilizers. Closed kinetic chain exercises are followed by slow, backwards barefoot walking (e.g., "airwalk"), one-legged proprioception exercises, and later core strengthening and plyometrics for core stability. Athletes are not allowed to walk barefoot and should wear supportive shoes routinely for 4-6 wk. Cuboid position should be monitored initially weekly if possible, and then spaced out appropriately on an individualized basis.

Occasionally a single, small bolus corticosteroid injection into or around a symptomatic cuboid articulation may help alleviate persistent pain after reduction is accomplished and maintained.

Return to activity should be individualized based on the mechanism, duration, and severity of injury plotted against demands of the specific sport. Immediate return is possible after minor, acute subluxations that maintain reduction successfully and are associated with immediate symptom relief after reduction. Pain-free return to play after more significant acute, subacute, and chronic subluxations may take place over weeks to months.

Rarely, surgery may be needed to address problematic cuboid articulations, but reports of outcomes are sparse, and surgery should be considered only as a last resort.

CONCLUSION

Cuboid subluxation involves injury and displacement of the cuboid and surrounding tissues, resulting in localized pain over the cuboid and occasional problems pushing off with the foot and toes while dancing or running. True incidence and exact proof of proposed subluxations and mechanisms are difficult to gauge. Various proposed mechanisms of injury lead most commonly to plantar and medial subluxations, and dorsal subluxations are rare. The diagnosis primarily is clinical, relying on appropriate history and physical examination. Traditional diagnostic imaging generally is unhelpful, but further exploration using ultrasound is intriguing. Conservative measures hinge around successful cuboid manipulation and reduction followed by include relative rest, activity modification, physical therapy, and external cuboid support with a pad, taping, orthotic, appropriate footwear, and/or bracing. Many athletes may return successfully to activity shortly after symptoms resolve. Appropriate awareness and understanding of this condition will lead to accurate diagnosis and improved outcomes.

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