Midfoot Sprain Versus Lisfranc Injury (Midfoot Dislocation +/- Fracture)

Edited by Christopher DiGiovanni, MD

Summary

A Lisfranc injury is a significant injury that involves the midfoot and often has a prolonged recovery time. This injury constellation can involve any combination of fracture, joint dislocation, and/or joint subluxation (incomplete dislocation) to this anatomic region. By definition, a true Lisfranc injury involves at minimum a destabilizing injury to the ligamentous complex of the midfoot, resulting in incongruity and/or instability of one or more of the tarsometatarsal joints. Fractures alone in the midfoot are not necessarily a Lisfranc injury if no joint instability can be identified (instead, they are more aptly termed isolated fractures in the midfoot).  The more joint instability and fractures found in the midfoot, generally the more severe the LIsfranc injury.  Significant disruption of these midfoot ligaments (Figure 1), especially with superimposed fracture of the midfoot bones, typically leads to immediately and often chronic pain, swelling, and 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 injury to the midfoot, whereby these ligaments are injured (perhaps stretched or partially torn) but not rendered unstable, is more appropriately called a midfoot sprain rather than a true Lisfranc injury—even though the area involves the five “Lisfranc joints” comprising the tarsometarsal arch (tarsometatarsal joints 1-5).  A midfoot sprain occurs when some of the midfoot ligaments are incompletely torn, but the bones and midfoot joints remain  in their normal position—and are hence inherently stable and do not generally require surgery.  Stable Lisfranc injuries are treated with rest, immobilization, and often a period of non-weight-bearing. Legitimate Lisfranc injuries, on the other hand, are inherently unstable and involve a midfoot at risk of progressive articular collapse and/or incongruity, and these are generally operative problems.  True Lisfranc injuries are associated with a level of disruption of the midfoot ligaments that leads to malalignment of the midfoot joints (tarsometatarsal joints).  Because of this instability, these injuries should typically be treated with surgery to reposition and stabilize the joints.  Making the distinction between a midfoot sprain and an overt Lisfranc injury, therefore, is of paramount importance with respect to treatment, outcome, and prognosis.

This anatomic region involving the midfoot articulations 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 of varying consequence (involving anywhere from one to all five of the tarsometatarsal articulations) to this constellation of joints.  As a result, he often needed to performed an amputation through the middle part of the foot. The joints through which he amputated now bear his name, as does the major stabilizing ligament that runs from the medial cuneiform to the 2nd metatarsal.

Figure 1A: Lisfranc Joint
Figure 1B:  Lisfranc Fracture
Lisfranc Joint of Foot Figure 1B -Lisfranc Injury -x-ray image Normal vs Injured

Clinical Presentation

Lisfranc injuries typically occur when the midfoot is excessively loaded in abduction, external rotation, and/or dorsiflexion, leading to partial or complete tearing of the strong midfoot ligaments (Figure 1A and 1B). The primary forces also include axial loading (from heel toward toes), and some degree of rotation through the middle joints of the foot. This can occur via a number of mechanisms including:

  • A twisting injury such as often occurs in sporting activities (ex. football), where the toes are planted on the ground and the heel is loaded.
  • A slip and twist to the foot while descending a step or curb.
  • Impact of the foot on the brake pedal, such as occurs in a motor vehicle crash.

Patients with Lisfranc injuries usually have significant swelling and pain in the midfoot, and can often exhibit bruising on the bottom of 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

Physical examination reveals specific tenderness to palpation across the midfoot region (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 aspect (bottom) of the foot is common and should raise suspicion for a significant injury.

Figure 2:  Location of Pain

Lisfranc Injury of Foot

Figure 3: Bruising from Lisfranc Injury

Figure 3 -Bruising from Lisfranc Injury

Imaging Studies

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 midfoot injury is stable (sprain) or unstable (Lisfranc).  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 (obtaining an X-ray while twisting the foot) to determine the stability of significant but occult midfoot instability. These tests are important, because they are dynamic assessments of a dynamic problem.  CT and MRI scans are more static assessments of these injuries, and can sometimes miss the occult injuries.

Classification

There are several classification systems for LisFranc injuries, however the crucial determination is whether or not the injury is stable or unstable.

Treatment

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 that is consistent with midfoot sprain, full recovery can still take many months.

Displaced (Unstable) Lisfranc injuries (displaced and/or occultly unstable midfoot joints) are usually treated surgically. Surgery is performed to restore joint alignment and stabilize the joint(s) with screws and sometimes plates (Figure 4). This allows the bones and the ligaments to be reduced and then 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. Recovery can take upwards of a year.

Figure 4: Surgical Treatment of Lisfranc Injury

Surgical Treatment of Lisfranc Injury

Recovery From Surgery

Recovery from midfoot sprains or overt Lisfranc injuries are lengthy, because the midfoot must absorb tremendous stress during routine stance and gait (weightbearing, stair climbing, walking, running, etc). Post surgical treatment and rehabilitation efforts are thus dependent upon the nature of the initial injury, specific surgical treatment, and the surgeon’s preference. For a major Lisfranc injury, a typical recovery protocol would include:

  • 2 to 3 week period of splinted non weightbearing, until swelling and discomfort settle down, and, if surgery was required, sutures can be removed.
  • 6- to 8-week period of gradually progressive partial weight bearing in a specialized brace or cast.
  • Gradual transition to weight bearing as tolerated in a specialized walking boot for an additional 4-8 weeks.
  • Wean from the boot to a stiff sole shoe at 10-14 weeks from surgery, perhaps with subsequent use of a customized semirigid midfoot arch support.

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.

Edited on December 23, 2015