Expert Insights On Detecting Lisfranc`s Injuries

Lisfranc’s injuries, as found at the tarsometatarsal joint, are rare, according to the literature. Only 1 percent of all fractures are found at the tarsometatarsal articulation with an incidence of one per 55,000 people per year.1 These injuries are two to four times more likely to occur among young to middle-aged men as opposed to female patients.1-3 Overall, though, the injury is still a rare phenomenon. Aitken and Poulson reviewed 82,500 fractures over a 15-year period and found only 16 cases of Lisfranc’s fractures.4 But are these injuries as rare as we think they are? The historically low reported incidence may be a function of often misdiagnosed and/or “underappreciated” tarsometatarsal injuries. Indeed, these injuries often present with subtle clinical and radiographic findings. Clearly, a strong appreciation of the complex functional anatomy and an appropriate index of suspicion are essential to detecting and treating Lisfranc’s joint injuries. Reviewing The Anatomy Of The Lisfranc’s Joint The Lisfranc’s joint or tarsometatarsal articulation is comprised of five metatarsal bases, three cuneiforms and the cuboid. The skeletal elements are joined together by dorsal, interosseous and plantar ligaments and the articular capsule of the joints. Transversely, the Lisfranc’s complex forms a convex arch anteriorly. In the frontal plane, it forms a symmetric arch, with the wedge-shaped base of the second metatarsal acting as the “keystone,” affording a high degree of osseous stability in this plane.5 Metatarsals one, two and three articulate respectively with the medial, intermediate and lateral cuneiforms, which in turn articulate with each other. The architecture of the second cuneiform creates a recess of sort for the interposition of the second metatarsal base, which articulates with each cuneiform. This creates a mortise and “locks” the entire tarsometatarsal complex.6 The skeletal elements of this complex are joined together by capsuloligamentous restraints. The articular capsule is divided into the medial, central and lateral compartments. This capsule is formed by a fibrous membrane lined internally with synovium. The first metatarsal and medial cuneiform compromise the medial compartment, while the central compartment includes the second and third metatarsal and their respective cuneiforms. Finally, the lateral compartment is defined as the fourth and fifth metatarsals and the cuboid. DePalma, Santucci and Sabetta studied 20 cadaveric feet and found significant variability exists in the course and structure of the reinforcing ligaments across Lisfranc’s joint.5 All specimens showed a ligamentous system consistent with dorsal, interosseous and plantar ligaments. The dorsal ligaments follow a longitudinal, oblique or transverse course. The longitudinal and oblique ligaments unite the bases of the metatarsals with their respective tarsal bones while the transverse ligaments include the dorsal intertarsal and intermetatarsal ligaments. The interosseous ligaments transversely connect the lateral four metatarsals, but are absent between the first and second. Instead, the second metatarsal is connected to the first tarsometatarsal joint obliquely from the proximal medial aspect of the second metatarsal base to the lateral distal aspect of the medial cuneiform by the Lisfranc’s ligament.1, 5-7 This ligament is the largest of the complex. The absence of a ligament connecting the first metatarsal to the tarsal bones is an inherent weakness of this complex and is responsible for the specific injury patterns you would see with these injuries. The interosseous ligaments connect the cuneiforms and cuboid, and are the most powerful attachments between these bones. As I noted above, the plantar ligaments correspond with the dorsal ligaments in shape and organization, although they are more robust. The strongest in this complex is that which connects the medial cuneiform and second and third metatarsal bases. Sarrafian describes this ligamentous complex as the main stabilizer of the tarsometatarsal articulation.7 From a functional anatomical perspective, the Lisfranc’s joint is divided into a medial, central and lateral component. The individual “columns” provide stability both medially and centrally. The fourth and fifth metatarsal/cuboid articulation provide for prerequisite motion through the lateral column of the midfoot. What About The Classification Systems? Several classification systems have been promulgated specific to Lisfranc’s injuries, although none of them has emerged as a strong prognostic indicator of clinical outcome.8 A deficiency of these classifications is a current lack of correlation between direct and indirect injuries and their treatment, as well as the various patterns and degree of soft tissue and osseous injury. None of the current classification schemes encompass injuries to adjacent structures, which may also be involved in a Lisfranc’s injury. The Myerson, et. al., modification of the Hardcastle classification is the most commonly used scheme for Lisfranc’s injuries.3 The classification is as follows: • Type A: total incongruity that causes displacement of all five rays in either the lateral or dorsal plantar direction. • Type B: partial incongruity fractures that indicate medial dislocation of the first ray or lateral dislocation of the tarsometatarsal joints. • Type C: divergent with partial or total displacement. Key Symptoms And Signs: What To Look For In Your Clinical Exam When patients present with a midfoot injury with accompanying pain and/or edema, you should consider the possibility of a Lisfranc’s fracture or dislocation. Keep in mind that polytraumatized patients often sustain foot fracture/dislocations, which may be underappreciated at the initial presentation, and may later be complicated with posttraumatic sequelae, including pain, disability, malalignment, arthrosis or combinations of the same. Tarsometatarsal fracture/dislocations often present with subtle clinical findings, which may indeed correlate with significant soft tissue and osseous insult. Obvious closed or open injuries commonly present with a grossly appreciable acquired deformity. Occult injuries may present with pain, minimal edema, absent gross deformity and near normal plain radiographs. Careful palpation and a clinical stress examination of the respective components of the tarsometatarsal articulation often reveal “zones” of subluxation and instability. Gross edema, pallor and exquisite pain upon passive extension and flexion of the hallux and lessor digits often are commensurate with an established or impending compartment syndrome. You must exercise care in evaluating and managing compartment syndrome associated with Lisfranc’s injuries. Trauma or fracture blister formation is a clinical sign of significant soft tissue injury. Appropriate management is critical towards optimizing the local soft tissue envelope prior to surgical management and definitive treatment. Essential Diagnostic Pointers When you suspect a Lisfranc’s injury, be sure to obtain standard radiographs, including an AP, lateral and medial oblique view. Often, you’ll need to get non-weightbearing views. In order to ensure quality X-rays, make sure they are perpendicular to the axis of the tarsometatarsal joint. Ideally, you should evaluate each metatarsal and corresponding articulation with the respective cuneiforms and cuboid for congruity, displacement or fracture. In general, you’ll be able to recognize displacement of 2 mm or greater of the tarsometatarsal articulation on appropriate plain film views of the foot. Keep in mind though that comparison views of the contralateral foot may be helpful in detecting subtle changes, including occult fractures and subluxation injuries. At times, dorsiflexion/abduction and plantarflexion/adduction stress views of the tarsometatarsal joint with or without appropriate anesthesia may assist you in qualifying the degree of instability to the Lisfranc’s joint. In comparison, the radiographic parameters of a “normal” tarsometatarsal relationship are as follows: • AP view. The medial cortical margin of the medial cuneiform is contiguous with the medial cortical margin of the second metatarsal base on plain and stress radiographs. • Medial oblique view. The medial cortical margin of the cuboid (uninvolved) is contiguous with the medial cortical margin of the fourth metatarsal base on plain and/or stress radiographs. • Lateral view. No existing dorsal and/or plantar translocation or displacement of the cuboid or respective cuneiforms is noted in relationship to the respective metatarsal bases. • AP stress view. No greater than 2mm of displacement is noted on forced stress abduction/adduction of the tarsometatarsal articulation. CT imaging has been suggested as an adjunct to comprehensive radiographic evaluation of Lisfranc’s injuries. In select cases, CT imaging may be helpful in refining surgical planning for approaches to open management of severe comminuted injuries and planning for “bridging” over adjacent joint injuries involving the greater tarsus. However, plain films, comparison views and stress examination under fluoroscopic guidance are the mainstay imaging studies for determining definitive treatment of Lisfranc’s fracture/dislocations. How To Ensure Optimal Treatment There is significant potential for long-term morbidity following a tarsometatarsal injury. The goal of treatment is to restore the injured joint complex to a stable, plantargrade position. The current emphasis for displaced Lisfranc’s fracture/dislocations (greater than 2 mm) involves surgical realignment and anatomic reduction via a stepwise approach to the joint complex. (You would reserve cast immobilization for the purely ligamentous sprains without subluxation and demonstrable instability, and those patients who are not considered viable surgical candidates.) Various techniques utilizing K-wire, screws, staples and external fixation devices have been advocated. Regardless of the surgical technique(s) employed, stable anatomic reduction is critical for ensuring an optimal outcome. To facilitate open reduction techniques, one may utilize wire finger traps and/or small external fixators to apply longitudinal traction (ligamentotaxis) to the involved metatarsals. A standardized incision plan generally includes a medially-based, a central and a lateral approach for access to the medial, central and lateral “column” of the Lisfranc’s joint complex. One can also employ percutaneously inserted K-wires and/or screws toward achieving anatomic restoration and stability to the joint complex. Direct visualization is often desirable, given the intra-articular fragments at the metatarsal bases and associated communition. Also keep in mind that soft tissue interposition may negate precise anatomic reduction via purely percutaneous techniques. One may choose a combination of K-wire fixation or screw fixation. Various studies have demonstrated acceptable results with both methods. Either way, one’s goal in treating these acute injuries is to achieve anatomic reduction, stability and restoration of congruent alignment to the tarsometatarsal joint. In Conclusion Lisfranc’s fracture/dislocation is not a common entity, although acute injuries can be difficult to diagnose. Timely and accurate clinical assessment and radiographic evaluation are the mainstay of initial management. Generally, anatomic reduction and stabilization are essential for achieving a satisfactory outcome. Precise restoration of the congruity and functional relationship involving the respective metatarsals and adjoining lesser tarsus is paramount. Much of the recent literature suggests ORIF as the standard of care. Ensuring anatomic reduction and appropriate postoperative management will optimize clinical outcomes. However, be aware that, in certain cases, posttraumatic sequalae may be inevitable even with timely and accurate anatomic reduction. Restoring alignment via an appropriate arthrodesis may be required for cases which are initially neglected, develop significant arthrosis or remain symptomatic in spite of appropriate care. Dr. Caldarella is a Fellow of the American College of Foot and Ankle Surgeons. He practices in the Department of Podiatric Medicine and Surgery at the Gundersen Lutheran Medical Center in La Crosse, Wis. Dr. Borchers is a Chief Resident in the aforementioned department at the Gundersen Lutheran Medical Center. Dr. Caldarella would like to express special thanks to the Medical Media Department at the Gundersen Lutheran Medical Center and Andrew Saterbak, MD for their respective contributions.
 

References:

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