A Lisfranc (midfoot) injury is a significant injury that often has a prolonged recovery time. Fracture of the midfoot bones and/or disruption of the midfoot ligaments (Figure 1) leads to pain, swelling, and often an inability to weight-bear. During normal standing and walking, the ligaments of the midfoot are subject to forces that are 2-3 times body weight. These ligaments and bones must heal before normal walking can occur and this often takes many months. A stable Lisfranc injury (midfoot sprain) occurs when some of the midfoot ligaments are not completely torn, and the bones and midfoot joints are in their normal position. Stable Lisfranc injuries are treated with rest, immobilization, and often a period of non-weight-bearing. A displaced Lisfranc injury is associated with disruption of the midfoot ligaments, leading to malalignment of the midfoot joints (tarsometatarsal joints). Because of this instability, these injuries are usually treated with surgery to reposition and stabilize the joints.
This joint was originally described by Lisfranc (a Napoleonic era field surgeon). He noted that riders who got their foot caught in the stirrup when they were knocked off their horses would suffer a serious injury to this joint. As a result, he often needed to performed an amputation through the middle part of the foot. The joint through which he amputated now bears his name, as does the major stabilizing ligament that runs from the medial cuneiform to the 2nd metatarsal.
Lisfranc injuries occur when the midfoot is excessively loaded, leading to partial or complete tearing of the strong midfoot ligaments (Figure 1A and 1B). The primary forces include axial loading (from heel toward toes), and rotation through the middle joints of the foot. This can occur via a number of mechanisms including:
Patients with Lisfranc injuries usually have significant swelling and pain in the midfoot. They find it difficult or impossible to weight-bear due to pain. There is a wide spectrum of Lisfranc-type injuries that can occur, from partial disruption of the ligaments with a stable bony position, to complete disruption of the joints with associated fractures and dislocations. Because the ankle is often uninvolved, the injury may be minimized as just a “foot sprain”, so a high index of suspicion must be maintained to diagnose this injury in a timely manner.
Physical examination reveals pain in the midfoot area (Figure 2). There will often be significant swelling of the foot (Figure 3). Patients with Lisfranc injuries will not want to bear weight on the affected foot. In addition, manipulation of the bones of the midfoot will create significant discomfort, specifically twisting the foot downwards and to the outside (pronation and abduction of the forefoot). Bruising in the center plantar (bottom) of the foot is common and should raise suspicion for a significant injury.
X-rays are taken to identify whether the injury is displaced or non-displaced. Weight-bearing foot x-rays are helpful to determine if the Lisfranc injury is stable or unstable. Obtaining a comparison film of the other foot is beneficial to see the normal alignment of the person’s foot (which can vary from person to person). A CT scan or MRI may be necessary if the diagnosis or the extent of the injury is unclear. Small bony detail in this region of the foot, as well as subtle fractures and joint displacements, may be more easily identified with advanced imaging. Occasionally, it may be necessary to perform stress x-rays under anesthesia (obtaining an X-ray while twisting the foot while the patient is asleep) to determine the stability of the midfoot ligaments.
There are several classification systems for LisFranc injuries, however the crucial determination is whether or not the injury is stable or unstable.
Stable Lisfranc injuries are usually treated non-operatively. This involves immobilization in either a cast or a prefabricated boot. Patients often need at least a 6-week period where they are either non-weight bearing or minimally weight bearing. In a stable injury, the midfoot ligaments are strained but still intact, so once an adequate amount of healing has occurred, patients can increase their activity level. However, even with a non-displaced injury, full recovery can take many months.
Displaced (Unstable) Lisfranc injuries are usually treated surgically. Surgery is performed to restore joint alignment and stabilize the joint(s) with screws and sometimes a plate (Figure 4). This allows the bones and the ligaments to be held in place, which gives the ligaments a chance to heal. In some cases, it is necessary to fuse the involved joints (connect the two bones forever), eliminating the motion altogether. It is not uncommon that once the injury has healed removal of the hardware will be necessary, requiring another surgical procedure.
The post surgical treatment is dependent upon the nature of the injury, specific surgical treatment, and the surgeon’s preference. For a major Lisfranc injury, a typical recovery protocol would include:
A displaced injury takes many months of recovery. The majority of the recovery occurs in the first 6 months, but it is often a year or more before patients reach their point of maximal improvement.
If the surgical treatment fails or the joint damage from the injury leads to severe arthritis, then a fusion (arthrodesis) of the Lisfranc joints may be necessary. Despite the stiffness of a fused joint, most patients with successful fusion of the midfoot joints have good function of the foot.