The Lisfranc fracture is a specific type of fracture and dislocation of the joints in the midfoot, an area where a cluster of small bones forms an arch on top of the foot between the ankle and the toes. This fracture was first described by the French doctor and surgeon Jacques Lisfranc de St. Martin, who worked in Napoleon's army. This type of injury mostly occurred when a horseman fell while riding, having trapped his foot in the stirrup. Falling from a height of two or three stories can also cause this fracture. The Lisfranc fracture normally requires surgery, and should be performed by a surgeon specialized in foot surgery.Normal anatomy of the Lisfranc joint
The Lisfranc joint is actually composed of 5 small joints, independent and different in size, position, and motion. A transverse line through these joints is not straight but highlights a recess formed by the second tarso-metatarsal joint. These joints are bound by thick plantar ligaments that form an interlocking pattern between the tarsal and lesser MT bones 2-5; no inter-metatarsal ligaments exist between the first and second metatarsal, which is why they often exhibit divergent behavior.
Motility of tarso-metatarsal joints
Motion at the tarso-metatarsal joints is variable. It is known that the second joint is the stiffest, with minimal motion. The third and first tarso-metatarsals exhibit progressively more motion. The lateral 2 tarso-metatarsal joints demonstrate roughly 3 times more motion. These motions are significant in the function of the foot and must be preserved to maintain normal function.
Mechanism of joint movement
The medial 3 joints are important for their rigidity and shock absorption, while the lateral joints are important for their mobile contributions to balance.
This principle is important in treating these injuries.
Possible causes of Lisfranc injuries
The 2 major causes of Lisfranc injuries are:
* Low-energy loading observed in sports-related injuries: In this case, tarso-metatarsal injuries are caused by a direct blow to the joint or by axial loading along the metatarsal. This could happen with medially or laterally directed rotational forces.
* High-energy loading observed in motor vehicle and industrial accidents: In this type of accidents the method of loading is not significantly different, but the energy absorbed by the articulations results in significantly more collateral damage to bony and soft-tissue structures.
Mechanisms of Injury
Lisfranc joint complex injury can occur as a result of direct or indirect trauma. Direct trauma occurs when an external force strikes the foot, while in case of indirect trauma, force is transmitted to the stationary foot so that the weight of the body becomes a deforming force.
Functionally, the foot is divided into three sections:
* the hindfoot, which absorbs shock during ambulation
* the midfoot, which helps translate force and provides rotational stability of the foot
* the forefoot, which assists in the toe-off phase of gait
The Lisfranc joint promotes energy dissipation by allowing force to be transferred between the midfoot and the forefoot.
Signs and symptoms
Lisfranc fracture-dislocations are often mistaken for sprains because in both cases the top of the foot may be swollen and painful, possibly with some bruising. A secure sign of fracture is that, if the injury is severe, the patient may not be able to put any weight on the foot. Also, Lisfranc injuries are often difficult to see on X-rays. This is important because unrecognized Lisfranc injuries can have serious complications such as joint degeneration and compartment syndrome (pressure within muscles damages nerve cells and blood vessels).
Diagnosis of Lisfranc fracture
Besides marked swelling and radiographic changes, the Lisfranc joint injury can be extremely difficult to diagnose because some significant subluxation or lateral deviation of the forefoot is rare. Swelling in the midfoot region and an inability to bear weight may be the only findings that suggest the diagnosis.
Physical Examination: When Lisfranc joint complex injury is suspected, palpation of the foot should begin distally and continue proximally to each tarso-metatarsal articulation. Pain is one of the most important symptoms, localized to the medial or lateral aspect of the foot at the tarso-metatarsal region on direct palpation. Another diagnostic clue is the patient's inability to bear weight while standing on tiptoe. The dorsalis pedis artery courses over the proximal head of the second metatarsal, so its pulse should be evaluated.
Radiographic findings: This is probably the most important diagnostic tool for making an accurate diagnosis. The initial radiographs of a suspected Lisfranc joint injury should provide several views, as well as a 30-degree oblique view. A weight-bearing radiograph is also necessary, because a non-weight-bearing view may not reveal the injury. The doctor should then compare the diastasis between the base of the first and second metatarsals or the medial and middle cuneiforms with the unaffected side.
On the radiograph, dislocation of the tarso-metatarsal joint is indicated be several secure signs such as:
* loss of in-line arrangement of the lateral margin of the first metatarsal base with the lateral edge of the medial (first) cuneiform
* loss of in-line arrangement of the medial margin of the second metatarsal base with the medial edge of the middle (second) cuneiform in the weight-bearing anteroposterior view
* the presence of small avulsed fragments, which are further indications of ligament injury and probable joint disruption
Computed tomographic (CT): A CT scan, or bone scan, could be extremely helpful in diagnosing difficult cases of Lisfranc joint injury. Radiographic displacement or flattening of the longitudinal arch of the foot is associated with a poor prognosis, and this finding may also correlate well with the patient's functional result, even after treatment.
Treatment
Early diagnosis of a Lisfranc joint injury is crucial for proper management and the prevention of a poor functional outcome. With an extensive knowledge of both conservative and operative treatment options, a doctor should be able to decide whether to treat the injury non-operatively or refer the patient to an orthopedist.
Non-operative Treatment: If the doctor, after physical examination, decides that this could be a mild or moderate sprain, and the radiograph shows no diastasis, simple immobilization is suggested. A short-leg walking cast, a removable short-leg orthotic, or a non%26shy;weight-bearing cast is recommended for four to six weeks or until symptoms have abated. After the period of immobilization, ambulation and rehabilitation exercises should be progressive and, in most cases, all symptoms will be resolved. If the symptoms persist up to two weeks after rehabilitation has begun, a repeat weight-bearing radiograph must be obtained to evaluate the joint articulation because it could be a case of delayed separation.
Operative Treatment: If the doctor decides that surgical repair is necessary it should be done within the first 12 to 24 hours after the injury. Alternatively, surgery can be performed after seven to 10 days to allow the reduction of swelling. There are several types of surgical operations and, while some orthopedists prefer closed fixation with percutaneous K-wires, others report that this method does not hold anatomic reduction and fixation. An alternative method involves the use of open reduction and internal fixation with AO screw fixation.
Postoperative Period: After open reduction and internal fixation, the foot should be immobilized in a cast for eight to 12 weeks with minimal weight-bearing. For three months after cast removal, the patient should wear a protective shoe with a well-molded orthotic for several weeks.
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