Influence of Retrograde Intramedullary Beam Position Within Talar Body on Radiographic Failure of Medial Column Fusion

Abstract

Category: Midfoot/Forefoot; Diabetes Introduction/Purpose: Intramedullary fixation in the form of retrograde beam or bolt has developed as an intriguing treatment option for unstable midfoot collapse. This is particularly true when it is desired to minimize the length of incision or to avoid surface implants in a compromised soft tissue envelope. However, prior studies have demonstrated high rates of complications associated with intramedullary midfoot fusion constructs (Ford et al., Butt et al). The goal of this study was to create a reproducible convention of classifying position of the terminal implant within the talar body and to uncover an association of relative position of the implant at the time of surgery with an increased risk of failure. Methods: Consecutive patients treated surgically from January 2017 to September 2022 with retrograde intramedullary fusion beam were identified; 44 were included in the final analysis. Average age was 62.7 years and mean radiographic follow up measured 12.86 months. Figure 1 demonstrates our classification of relative talar position. First, a line was drawn along the axis of the talar neck and carried posteriorly dividing the talar body into dorsal and plantar hemispheres. Then, a line was drawn from the anterior articular margin of the talar body to the lateral talar process. Parallel lines were then created in an equidistant fashion to divide the talar body into equal relative quartiles. At the time of surgery, the tip of the intramedullary beam was classified into relative axial and coronal position by a single observer. Our primary outcomes were hardware failure defined by implant fracture or cutout from the bone or additional surgery. Results: Successful midfoot fusion with intramedullary beam was achieved in 77% of our cases. 10 cases demonstrated hardware failure or the need for additional surgery. Relative implant position was classified as dorsal in 43% of cases and plantar in 57% of cases. Talar quartile depth was classified as 1st in 6% cases, 2nd in 32% of cases, 3rd in 30% of cases, and 4th in 32% of cases. There was no clinical or statistically significant difference between rates of failure based on relative implant position. Conclusion: Retrograde intramedullary fusion for medial column collapse remains a viable treatment option and our data supports successful fusion in most patients but a risk of failure remains significant. In this study, the relative position of the terminal implant within the talar body did not correlate with an increased risk of failure. There are likely other patient specific, or biomechanical factors leading to hardware fracture, cut out, or return of deformity. Continued analysis as sample size increases remains paramount to forming additional conclusions.