Research Day


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INTRODUCTION: The Lisfranc fracture or dislocation is a painful and disabling injury of the midfoot. While operative treatment remains the standard of care for displaced injuries, controversy exists on the best operative strategy. Some studies are critical of open reduction and internal fixation with screw fixation and report articular joint damage from the screws as a possible reason for persistent morbidity after surgery. To our knowledge, this concept has never been studied as the dimensions of the articular surface have never been reported. The purpose of the current study was to describe the morphology of the joints involved in Lisfranc fixation and to determine if it is possible to perform nonarticular transosseous internal fixation. Our hypothesis was that nonarticular transosseous Lisfranc fixation is possible with commonly available orthopaedic implants.

METHODS: Twelve cadaver feet were dissected and the associated joints between the medial (C1) and middle (C2) cuneiform and first and second metatarsals were quantified by calibrated digital imaging using software (ImageJ, 1.48k). Additionally, utilizing CT scan data, a computational three-dimensional (3D) model of the foot was developed using 3D Slicer v4.8. The first and second metatarsals and cuneiform bones were isolated. The model was transferred to MeshLab, processed, and transformed into a solid part using FreeCAD, an opensource CAD platform. Based on cadaveric dissection, joint surfaces were quantified and mapped, and potential nonarticular screw paths between the bones were determined. These fixation constructs were 3D printed for further visual analysis.

RESULTS: For the intercuneiform (C1-C2) connection, a mean of only 27.2% of the lateral face of C1 and 43.0% of the medial face of C2 was articular cartilage. Three variations of articular joint morphology were observed on C1 and two variations on C2. From the 3D models it was determined that a joint sparing, transosseous screw trajectory is possible between the medial cuneiform and the second metatarsal and between the medial and intermediate cuneiform. These screw paths were large enough to accommodate for even the largest clinically useful screw diameter (>5mm). The screw trajectories are roughly perpendicular to the long axis of the foot and take a plantar-medial to dorsal-lateral orientation with one screw from the C1 to the second metatarsal and one screw from C1 to C2.

CONCLUSION: The clinical significance of the current study is that internal fixation with screws can be performed without causing articular joint damage. Additionally, the articular surface is quantified for the first time and may be smaller than some surgeons realize. This study demonstrates the orientation required to avoid articular damage and helps guide the surgeon on the placement of these screws. The described use of screws in the current study (as opposed to plates and screws) would save thousands of dollars per surgery and still have the added benefit of avoiding damage to the articular joint surface.

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