Step-By-Step Evaluation of Midfoot Fractures
In this review article, orthopedic surgeons remind us how midfoot injuries called Lisfranc injuries come about, why they are called by that funny name, how the physician makes the diagnosis, and what type of treatment is called for.
Most people have a general idea of what is meant by the midfoot -- that area between the base of the toes and the ankle/heel complex. The proper anatomical term is the tarsometatarsal (TMT) joint. Metatarsals are the long bones of the forefoot. These are the bones of each toe between the ankle (tarsal bones) and the bones we usually refer to as the toes.
Lisfranc injuries describe any injury that occurs at the tarsometatarsal joints. This could be at the base of any of the five metatarsals (toes) or the place where the metatarsals glide against the tarsals (ankle bones). There is also an actual Lisfranc ligament at the base of the second toe. Damage to this ligament can also be called a Lisfranc injury.
Where does the term Lisfranc come from? The French surgeon (Dr. Jacques Lisfranc) who served in Napoleon's army back in the 1800s. He treated a soldier with this type of injury, named it after himself, and the rest is history.
The bones, ligaments, and connective tissue that form the entire Lisfranc area are important in keeping a strong, stable midfoot with a supportive arch. Injuries to this area can cause collapse of the arch, deformity, pain, and loss of foot function. That's why an early and accurate diagnosis is important followed by proper treatment.
The surgeon relies on what the patient says about how the injury came about. There can be a variety of ways Lisfranc's injuries can occur. Any time enough force is applied to the top of the foot in a downward direction, ligament tears, fractures, and dislocations can occur.
Car accidents, falls from up high down to the ground, having a horse stand on your foot (or other crush injuries) -- these are the kinds of events that occur that contribute to a Lisfranc injury. Likewise, stepping off a curb or step without realizing it or unexpectedly catching the heel on the curb or step can result in a Lisfranc injury. Athletes are also at risk for midfoot injuries of this type.
If the surgeon doesn't see the patient right away, there is usually a report of foot bruising, swelling, and pain. Obvious soft-tissue trauma (either seen or reported), especially accompanied by mid-foot deformity or loss of an arch is diagnostic. The surgeon will likely order imaging studies.
First, X-rays are taken. The radiologist looks for any obvious (or subtle) fractures, bone displacement, joint narrowing, and displacement of the toes or other obvious signs of a problem.
X-rays help show whether an injury is stable or unstable. That's an important distinction when trying to decide what kind of treatment (conservative care versus surgery). A tiny fleck of bone at the base of the second metatarsal may be a sign of an avulsion injury. Avulsion means the soft-tissue ligament or tendon attached at that area has pulled away from its insertion to the bone taking a small piece of bone with it.
If a ligamentous tear is suspected, CT scans are ordered. MRIs may be used when there is edema (swelling) and the surgeon suspects a more subtle injury. There are hands-on clinical (stress) tests that can also be performed. The surgeon may use these to confirm a Lisfranc injury. If negative, then the injury is treated as a sprain.
For true Lisfranc fractures and/or Lisfranc soft tissue injuries, treatment is aimed at restoring alignment and stability. The authors provide a list of five steps that can be taken to determine when surgery is needed. We've mentioned all five: physical examination, X-rays, MRIs, CT scans, and stress tests.
Some surgical cases are obvious: the foot is deformed, the patient can't walk on it, and it isn't painful -- it's numb. Instability is the big key in deciding the best treatment because stable fractures and injuries can still be treated nonsurgically with a cast or walking boot.
When the damage is healed and immobilization is no longer needed, the patient is guided in finding the right (supportive) shoe. A special shoe insert called an orthotic is made and worn whenever weight-bearing. Total recovery time of a stable Lisfranc injury treated conservatively is about four months.
Even small malalignment problems of the midfoot should be treated surgically. This is not a very forgiving joint. Tiny shifts in alignment can lead to more injuries later and eventual disability from arthritis.
The surgeon uses an open incision to put the bones back in place and hold them there with pins, wires, metal plates, and/or screws. The procedure is called an open reduction and internal fixation (ORIF). Some surgeons do use a percutaneous (through the skin without an open incision) approach. A special real-time X-ray called fluoroscopy is used to accomplish this.
Post-operative care involves wearing a non-weight-bearing cast for three weeks. The cast is removed and a special boot is worn for another three to five weeks. Small amounts of weight are allowed on the foot at first. The patient is advised to gradually increase the amount of weight-bearing for the next few weeks. By the end of eight weeks, the patient should be able to put full weight on that leg.
At that point, the patient will be sent to a physical therapist for gait and balance training. When the screws are removed (usually around four months post-op), then the therapist helps the patient regain full motion, strength, proprioception (joint awareness), and kinesthia (movement awareness and accuracy).
These are important components of rehab to help prevent future injuries or re-injuries of the same area. This is especially important for the athlete who must make sudden changes in direction on the field or push-off on toes or jump and land on the midfoot.
The authors point out that patients (especially athletes) should be made aware of the fact that severe Lisfranc injuries don't always recover fully even with the best of treatment. They can achieve a stable foot but stiffness and pain may persist.
More research is needed to find future treatments that don't damage the joint, don't result in arthritic changes later on, and do provide fixation that lasts. Right now, a plate along the bottom-side of the joint is being tested as a possible alternative treatment technique. This approach is called dorsal plating. Another new method of fixation under investigation is an EndoButton designed to mimic the function of the Lisfranc ligament.
Studies will be needed to compare these new surgical fixation techniques against the methods currently being used. Although Lisfranc injuries are not common, they also aren't rare. With more people participating in sports activities, surgeons need to recognize Lisfranc injuries quickly and be prepared to treat them as effectively as possible.
Troy S. Watson, MD, et al. Treatment of Lisfranc Joint Injury: Current Concepts. In Journal of the American Association of Orthopaedic Surgeons. December 2010. Vol. 18. No. 12. Pp. 718-728.