Cuboid fractures

Introduction

Fractures of the cuboid can occur in isolation, but are often associated with other fractures and dislocations of the midfoot. They can occur through direct or indirect mechanisms. Indirect injury usually occurs through a torsional injury to the ankle and midfoot resulting in the cuboid being crushed between the calcaneus and metatarsals by forced plantar flexion and abduction. Direct injuries occur by direct blow or high energy crush injuries. However, injuries to the cuboid may be subtle and can be misdiagnosed as lateral ankle sprains.

Anatomy

The cuboid makes up the midfoot's contribution to the lateral column of the foot and serves mainly as a lateral column spacer block. Proximally, the cuboid has a saddle shaped articulation with the calcaneus. Medially, it articulates with the navicular nad lateral cuneiform. Distally, it articulates with the fourth and fifth metatarsals. These articulations provide for nearly all of the mobility of the lateral column of the foot. Additionally, the fourth and fifth metatarso-cubiod joints allow up to three times more motion than the medial three metatarso-cunieform joints. The longitudinal plantar ligament provides strong support of the plantar aspect of the calcaneocuboid joint. The peroneus longus courses on the planar surface of the cuboid in a lateral to medial direction.

Classification

There is no commonly used classification system. The OTA classification system may be used for research purposes. This classifies cuboid fractures as 76 with A- extra-articular, B- involving either the calcaneocuboid joint or metatarsocuboid joint, C- involving both major joint surfaces. Subsequently, the fracture pattern unique to each subcategory is given a number.

Type A: extraarticular
A1: extraarticular, avulsion
A2: extraarticular, coronal
A3: extraarticular, comminuted/crush
Type B: single joint articular
B1: sagittal
B2: horizontal
Type C: multiarticular, comminuted
C1.1 nondisplaced
C1.2 displaced

Presentation

Fractures of the cuboid can present with varying swelling and deformity of the lateral midfoot. Swelling and ecchymosis over the cuboid should raise suspicion of this injury and when other midfoot injuries are present , the cuboid articulations should be carefully inspected for subtle injury. There is usually direct tenderness to palpation over the cuboid and difficulty with weight-bearing.

Cuboid dislocation has been reported to occur in up to 9% of high performance athletes and 17% of ballet dancers and is termed cuboid syndrome. This presents lateral foot pain that radiates to the ankle and lateral metatarsals resulting in a sense of weakness in plantarflexion during push off. Similar to traumatic injuries, this injury is likely related to repetitive forced abduction of the forefoot. This diagnosis should considered differential of athletically active patients presenting with chronic lateral foot pain.

Diagnosis

AP, lateral and oblique views of the foot are usually sufficient to diagnose cuboid fracture. However, medial oblique views may better characterize the calcaneo-cuboid and metarocuboid articulations. Once the cuboid fracture is recognized, weight bearing views should be obtained to assess for occult ligamentous injury as well as CT scan to fully characterize the extent of the fracture and comminution.

Treatment

Nondisplaced fractures of the cuboid without evidence of collapse of the lateral column can be managed with non-weightbearing for 4-6 weeks in a short leg cast. Obtaining weight bearing films at two weeks post injury will detect occult ligamentous injuries. Weight bearing can be advanced as pain subsides.

Cortical avulsion fractures can be allowed to weight bear immediately in a walking boot.

Dislocation or subluxation in "cuboid syndrome" should be reduced with or without sedation after relieving peroneal spasm. Weight bearing can be advanced when the pain subsides.

Traumatic dislocation causes severe disruption of the plantar ligamentous support and should undergo open reduction with K-wire stabilization of the calcaneocuboid joint for 4-6 weeks.

Any loss of lateral column length or articular incongruity greater than 2mm are indications for open reduction and internal fixation. In the multiply injured foot, the cuboid should undergo open reduction and internal fixation prior to stabilizing other injuries as this will reconstitute the lateral column and facilitate reduction of other injuries. Open reduction and internal fixation of the cuboid will often require liberal use of bone graft to restore lateral column length as cancellous impaction often occurs at the time of injury once the cortex is disrupted. 2.7mm and 3.5mm cancellous lag screws and possibly a 3.5mm one-third tubular plate are usually adequate for fixation. Use of a laterally based external fixator intraoperatively aids in reduction and can be maintained postoperatively to prevent impaction.

In the severely crushed and comminuted midfoot, external fixation alone may provide adequate indirect reduction and restore lateral column length.

Complications

Late instability
Post-traumatic arthritis
Loss of the arch
Pronation deformity
Skin necrosis
Nonunion
Osteonecrosis

Red Flags and controversies

Primary arthrodeisis versus external fixation or open reduction and internal fixation for severely comminuted fractures.

Outcomes

Outcomes are difficult to interpret due to the lack of large outcome series.