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Sep 11, 2006
LisFranc Fracture
by SirGan
 The Lisfranc fracture is one specific fracture and dislocation of the joints in the midfoot. This is where a cluster of small bones forms an arch on top of the foot between the ankle and the toes. Interesting fact is that this fracture was first described by the French doctor and surgeon Jacques Lisfranc de St. Martin, who worked in Napoleon's army. Experts are saying that 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 Lisfranc jointEvery patient should know that the Lisfranc joint is actually composed of the 5 small joints and. It is important to know that these joints are actually independent and they are 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. It is important to know that these joints are bound by thick plantar ligaments that form an interlocking pattern between the tarsal and lesser MT bones 2-5 and that no inter-metatarsal ligaments exist between the first and second metatarsal. This is the reason why they often exhibit divergent behavior.
Motility of tarso-metatarsal jointsAlthough some experts are claiming differently- the fact is that 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. Every patient should know that these motions are significant in the function of the foot and must be preserved to maintain normal function.
Mechanism of the joint movementSeveral researches done in the past have showed that the medial 3 joints are more important for their rigidity and shock absorption while the lateral joints are more important for their mobile contributions to balance. This principle is important in treating these injuries.
Possible causes of Lisfranc injuriesThe 2 major causes of Lisfranc injuries are:
Every patient should know that 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.
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 InjuryLisfranc joint complex injury can occur as a result of direct or indirect trauma. Reasonably- the fact is that 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 Lisfranc joint promotes energy dissipation by allowing force to be transferred between the midfoot and the forefoot.
Signs and symptomsBig problem is that Lisfranc fracture-dislocations are often mistaken for sprains because in both cases- the top of the foot may be swollen and painful. There may be some bruising. Experts are saying that secure sign of fracture is that, if the injury is severe, patient may not be able to put any weight on the foot. Another problem is that Lisfranc injuries are often difficult to see on X-rays. This is important because -unrecognized Lisfranc injuries can have serious complications such as:
Diagnosis of Lisfranc fractureBesidesmarked swelling and radiographic changes, the Lisfranc joint injury can be extremely difficult to diagnose. This is mostly 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 ExaminationEvery patient should know that, 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! The fact is that pain can localize 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. This is very important diagnostic. One artery called the dorsalis pedis artery courses over the proximal head of the second metatarsal which pulse should be evaluated!
Radiographic findingsThis is probably the most important diagnostic tool for making the accurate diagnosis! The initial radiographs of a suspected Lisfranc joint injury should several views, as well as a 30-degree oblique view. Patient should also know that one specific type of images called the weight-bearing radiograph is necessary, simply because a non-weight-bearing view may not reveal the injury. Every good 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 radiographs, dislocation of the tarso-metatarsal joint is indicated be several secure signs such as:
Computed tomographic (CT)Every patient should also know that Computed tomographic (CT) scanning or bone scanning could be extremely helpful in diagnosing difficult cases of Lisfranc joint injury. Some experts have suggested that 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.
TreatmentSeveral researches done in the past have confirmed that early diagnosis of a Lisfranc joint injury is the crucial thing for proper management and the prevention of a poor functional outcome. Good thing is that with a good knowledge of both conservative and operative treatment options, doctor should be able to decide whether to treat the injury non-operatively or refer the patient to an orthopedist.
Non-operative TreatmentGood thing is that, if the doctor, after physical examination, decides that this could be the cases of a mild or moderate sprain and the radiograph shows no diastasis, simple immobilization is suggested. In this case- treatment with a short-leg walking cast, a removable short-leg orthotic or a nonweight-bearing cast is recommended for four to six weeks or until symptoms have resolved. Good thing is that, after the period of immobilization, ambulation and rehabilitation exercises should be progressive and, in most cases- all symptoms will resolve. Every patient should also know that, 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 TreatmentExperts are claiming that, if 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. Every patient should know that an alternative method involves the use of open reduction and internal fixation with AO screw fixation.
After operationImportant thing to point out that after open reduction and internal fixation, most experts from this field suggest that the foot 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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