Simulated Weight Bearing and Articular Injury From Transarticular Screws In A Lisfranc Injury Model

Category: Midfoot/Forefoot, Trauma Introduction/Purpose: Successful treatment of Lisfranc injuries, relies upon anatomic reduction [1-3] and rigid fixation until bony or ligamentous healing has occurred and inherent stability has been restored. Historically, transarticular screw fixation has been the most common method of fixation, but optimal treatment remains controversial. Articular injury from transarticular screw fixation may lead to arthritis of the Lisfranc joints and future morbidity. To our knowledge only two studies have evaluated articular injury from transarticular screws [6,7]. Neither of these studies, and no other study to our knowledge has investigated relative increase in articular damage after simulated weight bearing. The aims of this study were: (1) create a ligamentous Lisfranc injury model and (2) compare relative increase in articular injury pre- and post-simulated weight bearing from screw toggle. Methods: 10 cadaver specimens underwent transarcticular screw fixation with 3.5 mm cortical screws in a ligamentous Lisfranc injury model. Digital photographs of the articular surfaces of the first and second tarsometatarsal joints were taken before and after cycling. Simulated weight bearing was performed with each specimen cycled 1,000 cycles at 222.4 N in a custom jig fixed in approximately 20 degrees of plantar flexion. After creation of the Lisfranc injury and prior to cycling with screw fixation, each specimen was cycled for 20 cycles to ensure we had created a reliable injury model. At each stage we assessed total relative rotation and diastasis between each of the bones of the Lisfranc complex. After simulated weight bearing hardware was removed and digital photographs were again taken. Articular injury was measured as a percentage of total articular surface pre- and post-cycling and was compared and statistical analysis performed. Results: Our model produced motion consistent with a ligamentous Lisfranc injury. Overall, the articular injury increased by 44.22% (p