Intertarsal injury is an injury to the area bounded by the Lisfranc region distally and the Chopart region proximally. It may involve the navicular-cuneiform or intercuneiform joints of the midfoot, or the cuneiform bones.
History and physical exam
These injuries may arise in athletics and be very subtle, or they may be the result of higher-energy injury and be more obvious. Their mechanism is similar to a Lisfranc midfoot injury or a similar twist, and they may indeed be part of a Lisfranc fracture dislocation. The high-energy injury is often part of a polytrauma and is often associated with other injuries, in the foot and other parts of the body. In the multiply-injured patient, intertarsal injuries and fractures may be picked up on the secondary survey. In the case of unconscious patients, care should be taken to check for unusual swelling, crepitus and/or deformity. If suspected, foot x-rays are indicated.
Plain x-rays will often show the injury pattern. CT with sagittal and coronal reconstruction is useful in obtaining a three-dimensional understanding of the injury. CT protocol should be thin cuts with large overlap.
Talonavicular joint function
The talonavicular (TN) joint allows for hindfoot motion in all planes. Loss of TN motion results in loss of complex hindfoot circumduction. It is therefore extremely important to retain TN function as it has a protective function for the adjacent joints. Loss of TN motion leads to adjacent joint degeneration (DJD). Retaining even a small amount of motion is thought to be protective for the adjacent joint function. The TN joint, because of its extensive range of motion, is also known as the “coxa pedis”.
As described above, the shape of the TN joint is important. In comminuted fractures of the navicular, there is great danger of losing the normal geometry. Every attempt should be made to reconstruct the shape of the navicular while maintaining soft-tissue attachments and blood supply.
The navicular has an oval shape on cross-section. Small branches of the posterior tibial and dorsalis pedis arteries comprise the blood supply of the navicular. The medial and lateral areas are more or less well supplied while the central section has the most marginal blood supply.
Maintain columnar length and relationship
Medial column length is crucial in maintaining the shape of the medial arch of the foot. If the navicular injury has resulted in comminution with loss of length, in reconstruction we must regain length, as well as normal geometry. Bridging the hardware distally and using bone graft will assure proper length of the medial column, overall shape and alignment of the foot. The form and function of the foot is dependent on the normal relationship between the medial and lateral columns. If the relative lengths of the medial and lateral columns are not maintained, foot deformity such as cavus or planus results. Relative shortening of the medial column leads to cavus whereas relative shortening of the lateral column leads to flat foot.
Combination of approaches
In some cases, a combination of both approaches may be indicated. If fracture care requires a more extensile approach, the advantages of better reduction are balanced against wider dissection causing stripping/loss of blood supply. If the dorsomedial approach is required, care should be taken to minimize dissection.
3. Soft-tissue considerations
Energy delivered to the foot and midtarsus dissipates not only through the bone, resulting in fractures, but even more so through the soft tissues. Therefore the higher the energy the more severe the soft-tissue injuries. Thus with these injuries we not only see swelling and blistering of the skin but we must remember that compartment syndroms do occur and most not be neglected.
Because of the soft-tissue component of these injuries surgery is usually delayed to allow soft tissues to settle before definitive surgical care. Soft tissues must take priority over the bony injury and once the “wrinkle sign” is present, indicating relative soft-tissue recovery, the likelihood of soft-tissue complication from bony surgery is decreased.
All severe midfoot trauma has a spectrum of soft-tissue injury. Rest, elevation and, in some cases, intermittent compression devices will help in resolving the soft-tissue swelling. Non-weightbearing is essential until the final treatment plan has been executed. The amount of swelling is a good indicator of the degree of soft-tissue injury. As the swelling recedes, the skin begins to wrinkle both on the lateral and medial side. The wrinkling of the skin is a good indicator of when surgery can be undertaken. Usually, one has to delay surgery for up to 14 days or more to decrease the incidence of postoperative wound complications. Stability of the skeleton allows for quicker recovery of the soft tissues. Therefore immediate insertion of external fixators on the medial and lateral side allows for provisional reduction of both the medial and lateral rays and provides stability for the skeletal component of the injury and prevents further bony and soft-tissue injury. Stability usually decreases pain but if after provisional reduction the degree of pain escalates, one must think of a compartment syndrome. In addition to stabilization, elevation, compression and icing help to decrease the swelling. Severe soft-tissue and/or vascular injury may necessitate immediate amputation at the appropriate level.
These injuries are surgical emergencies. They require urgent debridement and reduction and stabilization of the bony component of the injury. Whether one carries out only external fixation or a definitive ORIF will depend on the nature of the injury. Articular components, if possible, are best dealt with definitively at the time of the initial reduction and fixation. Because most injuries to the tarsus involve articular surfaces, if these are essential to the biomechanics of the foot, immediate fixation may become necessary. For provisional fixation here as in other injuries the immediate placement of medial and lateral external fixation stabilizes the columns of the foot and prevents further soft-tissue trauma. Frequently, temporary percutaneous wire fixation is used to hold preliminary reductions while the soft tissues are healing before definitive bony reconstruction.
4. Temporizing measures
Medial and lateral external fixation (with distractor device to restore columnar length) should be applied as soon after the injury as possible to stabilize the foot and decrease further injury to the soft tissues. Temporary percutaneous K-wires can be used to reduce displaced fragments, and are left as temporary fixation.
Due to the high-energy injury of these fractures, the soft tissues, including capsule and periosteum are disrupted. Care should be taken to minimize soft-tissue stripping during the approach. This will help maintain blood supply to the fragments.
Combination of approaches
In some cases, a combination of both approaches may be indicated. If fracture care requires a more extensile approach, the advantages of better reduction are balanced against wider dissection causing stripping/loss of blood supply.
If the dorsomedial approach is required, care should be taken to minimize dissection.
Intraoperative use of distraction
The distractors are sophisticated devices and are ideally suited for the restoration of column length and alignment. However, distraction and reduction can be achieved equally with external fixators. The restoration of length and alignment allows access to the fracture sites and articular surfaces. As already discussed, the restoration of columnar length and alignment is important in the treatment of the soft-tissue components of these injuries.
Restoration of the articular surface
In dealing with articular fractures one should endeavour to preserve all articular fragments. Free articular fragments (having an articular surface), if sufficiently large, can be salvaged and secured with K-wires. The articular surfaces of the tarsal bones with the exception of the talo-navicular articulation are not essential for the preservation of normal biomechanics of the foot and therefore, if too badly fragmented, can be fused at the time of the reduction. Column length and alignment should still be maintained. Small flat surface elevators are very helpful in reducing the small fragments.
Bone graft and preliminary fixation
Once the fracture(s) has/have been reconstructed, the distraction can be adjusted. It is helpful to have an x-ray from the uninjured side. It is helpful for comparison of one’s reduction as the normal side serves as a template. It will help in judging length and overall morphology. If the restoration of length has resulted in bony defects, these should be filled with bone graft and any primary fusions should also be bone-grafted to facilitate spot welding.
7. Plate fixation
Choice of plate
The new locking technology and in particular the potential for variable axis fixation has greatly aided in the fixation of fractures of small bones. These plates can be used as means of achieving absolute stability in simple fractures and as bridging devices with relative stability in multi-fragmentary fractures. They greatly aid in maintaining and in restoring length and alignment.
The plate is contoured and any extra holes are removed. When inserting the screws (in the proximal row, adjacent to the talonavicular joint), care must be taken to prevent the screws from entering the dome-shaped joint. In the case of the newer generation variable-angle locking plates, the screws should be aimed distally, away from the talonavicular joint. This can also be accomplished by contouring non variable-angle locking plates, or using non-locking plates. In the case of severely comminuted fractures where stable / rigid internal fixation is not certain, the distractors can be replaced with an external fixator which can then be left in place while the bone heals.
Dressing Non-adherent antibacterial dressing is applied as a first layer. Sterile undercast padding is placed from toes to knee. Extra side and posterior cushion padding is added.
Immobilization A three-sided plaster splint is applied. The anterior area is left free of plaster to allow for swelling. Make sure that the medial and lateral vertical portions of the splint do not overlap anteriorly and that the splint does not compress the the popliteal space or the calf.
The plaster is then wrapped with more undercast padding. The entire construct is then wrapped with elastic bandages.
The patient should be counseled to keep the leg on a cushion and elevated. Remember not to elevate the leg too much as it may impede the inflow. The ideal position of the foot when the patient is supine is half way between the waist and the heart. While seated, the foot should be on a cushion and elevated, but if badly swollen the patient must be supine since elevating the foot while seated is not as effective in decreasing the swelling.
The OR dressing is usually left in place and not changed until the first postoperative visit at 2 weeks, when x-rays are obtained once the dressing is removed. If any complication is suspected (e.g. infection or compartment syndrome) the dressing must be split and if necessary removed to allow full inspection. Strict non-weight bearing should be maintained until there is evidence of healing, a minimum of 8 weeks. If one should use a removable functional orthosis instead of cast, it may be removed daily to begin gentle range of motion. Formal physical therapy should not begin in the early postoperative period.