Factors Influencing Postoperative Residual Diastasis after the Operative Treatment of Acute Lisfranc Fracture-Dislocation

Abstract

Category: Trauma; Midfoot/Forefoot Introduction/Purpose: Clinically, surgeons may frequently encounter residual diastasis between the medial cuneiform and 2nd metatarsal base after the operative treatment of acute Lisfranc fracture-dislocations. The purpose of this study was to identify factors influencing postoperative residual diastasis. We specifically focused on the preoperative fracture pattern using 3- dimensional computed tomography (3D-CT). Methods: Radiographic and clinical findings of 66 patients who underwent operative treatment for acute Lisfranc fracture- dislocation were reviewed. Patients were grouped according to residual diastasis evaluated by weight-bearing anteroposterior radiograph of the foot at the final follow-up. Residual diastasis was defined as distance between the medial cuneiform and 2nd metatarsal base greater than the distance on the contralateral side by 2 mm or more. Demographic parameters and fracture patterns based on preoperative foot 3D-CT were compared. A paired t-test was used to compare continuous numeric parameters, while a chi-square test was used for the proportional parameters. Statistical significance was set at P-value less than 0.05 for all analyses. Results: The mean age at operation, sex, body mass index, and the rate of underlying diabetes were not significantly different between the two groups (P>0.05 each). Preoperative foot 3D-CT evaluation showed that the rate of large (>25% of 2nd tarsometatarsal joint involvement), displaced (>2 mm) fracture fragments on the plantar side of the 2nd metatarsal base was more pronounced in the group with residual diastasis (P=0.001), while medial wall avulsion of the 2nd metatarsal base was more frequent in the group without residual diastasis (P=0.001). Conclusion: While treating acute Lisfranc injuries, surgeons should be aware of the presence of a 2nd metatarsal base plantar fracture. A dorsoplantar inter-fragmentary fixation can be considered if the fragment is large and displaced.