The First Tarsometatarsal Joint in Lisfranc Injuries.

Background: Lisfranc injuries are among the most debilitating injuries to the foot. Characterization of first tarsometatarsal (TMT) joint involvement in Lisfranc injuries is limited. Multiple studies have indicated that this joint is damaged in a variety of Lisfranc injury patterns, but there is sparse information regarding how often and in what form.

Methods: A retrospective review was performed of operative Lisfranc fractures from 2010 to 2020 with patients identified by codes. Hardcastle and Myerson Lisfranc injury classifications and computed tomography and radiograph characterizations of the first TMT joint were evaluated by 3 foot and ankle fellowship-trained orthopaedic surgeons. Radiographic characteristics were collected. Light's kappa coefficient evaluated interrater reliability for injury classification. Injury mechanism and Lisfranc classification effects on the first TMT joint were further assessed using inferential statistics.

Results: Of 71 patients with a Lisfranc injury of which 37 (52%) were high energy, 61 (86%) showed radiographic evidence of first TMT joint injury. A fragment was present in the TMT articular surface in 33 (47%) with median size = 8.7 mm and medial capsular avulsion in n = 25 (35%). Forty-eight patients (68%) had medial/lateral TMT joint incongruence ≥2 mm (median overhang = 4 mm), 21 (30%) had dorsal/plantar incongruence (median overhang = 6 mm). Angulation of TMT articular surfaces ≥5 degrees on the transverse/anteroposterior plane occurred in n = 32 (45%) and in n = 12 (17%) on the sagittal/lateral plane, which significantly differed between classifications ( = .020).

Conclusion: The overwhelming majority of Lisfranc midfoot injuries seen at our tertiary referral center had imaging evidence of damage to the first TMT joint (86%), and the incidence may be higher. The most common patterns of first TMT joint involvement we found were joint incongruity, articular surface fractures, angulation of the articular surfaces, and medial capsular ligament avulsion fractures. A better understanding of injuries to the first TMT joint can help orthopaedic surgeons with diagnosis.