1 Diagnosis topenlarge
Fractures of the cuboid
On physical exam there will be pain and swelling. In the case of simple non-displaced fractures, or stress fractures, there is not likely to be foot deformity. In comminuted crush “nutcracker”-type fractures there may also be deformity with shortening of the lateral column.
Plain x-rays will often show the fracture.
CT with sagittal and coronal reconstructions is useful in obtaining a three-dimensional understanding of the injury. CT protocol should be thin cuts with large overlap.
In the case of continued pain without abnormality on x-rays, a bone scan or MRI might be useful in uncovering a stress fracture.
2 Principles topenlarge
Unlike the TN joint, which is responsible for complex hindfoot circumduction, the CC joint is relatively unimportant for normal function. In fact, if fused at normal length, no loss of motion in the rest of the hindfoot occurs.
However, lateral column length is very important to maintain the shape and function of the foot. Therefore, cuboid length must be maintained.
3 Reduction topenlarge
Preparation of the fracture site
Fractures of the cuboid are best approached through a dorsolateral incision already described under the section dealing with approaches.
Often in these injuries, the soft tissues, including capsule and periosteum, are disrupted. Care should be taken to minimize soft-tissue stripping during the approach. This will help to maintain blood supply to the fragments.
Use of a small distractor is needed to restore the lateral column and cuboid length. Distraction also allows access to the fracture site and the joint surfaces.
Restoration of the articular surface
Free fragments with articular surface can be salvaged and secured with K-wires.
Use a curved elevator with a flat surface to restore the joint surface, using the opposing joint surface as a template.
Periosteal elevators come in many shapes and sizes, and having a variety of these is helpful with foot surgery.
Bone graft and preliminary fixation
Once the articular surface has been reconstructed, the distraction can be adjusted. It is helpful to have comparative x-rays from the uninjured side. This allows proper length and morphology to be judged.
The remaining defect can then be bone grafted.
While reconstructing the joint surface, check frequently to make sure that no malreduction is occurring.
Using the adjacent joint surface as a template is useful but if the fragment is secured to it with a transarticular K-wire, actual verification of the reduction is more difficult.
4 Bone-specific plate fixation topenlarge
Bone-specific plate fixation
The cuboid plate is contoured. When inserting the screws, care must be taken to prevent the screws from entering the joint. In the case of the newer generation variable-angle locking plates, the screws should be aimed away from the joint. This can also be accomplished by contouring non variable-angle locking plates, or using non-locking plates.
5 Bridge plating or external fixation topenlarge
In cases where the comminution does not allow single-bone osteosynthesis, bridge plating is indicated.
Plating can be used that stretches from the calcaneus across the cuboid and onto the base of the 4th and 5th metatarsals. This gives the construct added stability.
Since the 4-5 metatarso-cuboid joints should ideally be mobile, this bridge plate may require removal.
In the case of severely comminuted fractures where stable / rigid internal fixation is not assured, instead of bridge plating, the lateral column distractor can be replaced with an external fixation construct which can be left in place while the bone heals.
Supplemental fixation (screw or K-wire) can be placed from the fifth metatarsal (which can be rendered unstable by this injury), through the fourth metatarsal into the third metatarsal, or lateral cuneiform. This will further prevent lateral column shortening.