SLR - July 2021 - Eric M. Swenson
Reference: Sripanich, Y., Weinberg, M. W., Krähenbühl, N., Rungprai, C., Saltzman, C. L., & Barg, A. Reliability of Measurements Assessing the Lisfranc Joint Using Weightbearing Computed Tomography Imaging. Arch Orthop Trauma Surg. 2021 May;141(5):775-781.Level of Evidence: Level III
Scientific Literature Review
Reviewed By: Eric M. Swenson, DPM
Residency Program: Mount Auburn Hospital – Cambridge, MA
Podiatric Relevance: A common ligamentous injury encountered by the foot and ankle surgeon involves the Lisfranc complex. However, many of these injuries are overlooked or undiagnosed due to variable clinical and radiographic findings. Currently, the imaging diagnostic gold standard for Lisfranc instability consists of bilateral weightbearing radiographs for contralateral comparison and evaluation of joint space widening between the medial cuneiform and second metatarsal. Using this method, a diastasis of >2 millimeters relative to the contralateral foot equates instability. Advanced imaging is also useful in detecting these ligamentous abnormalities. Magnetic resonance imaging is the superior modality for soft tissue evaluation however, restricted due to non-weightbearing conditions for imaging. Computed tomography offers higher accuracy over plain films in visualizing osseous pathology but can offer the added benefit of acquisition during weightbearing. This study aimed to develop a protocol to reliably measure and assess Lisfranc disruption using weight bearing computed tomography (WBCT) imaging.
Methods: A retrospective analysis was performed on 96 patients who underwent WBCT. The unaffected side was utilized for assessment. Two methods of measuring the 2nd metatarsal to medial cuneiform distance were employed on both axial and coronal WBCT imaging in order to localize the Lisfranc ligament. Method I involved measuring a specific distance at the 2nd metatarsal base, and method II involved the use of bony landmarks. Both methods utilized the anatomic landmark of the Lisfranc ligament insertion on the 2nd metatarsal base as a reference point. Three independent observers recorded the measurements following the implemented protocol. Measurements were then repeated 28 days later without knowledge of prior measurements.
Results: The distance from the medial cuneiform to the second metatarsal base from the first measuring method displayed an average distance of 3.9 millimeters on axial imaging, and 3.8 millimeters on coronal. The second measuring method showed an average distance of 4.2 millimeters on axial imaging, and 4.0 millimeters on coronal. R values for intra- and inter-observer reliability for Method I ranged from 0.7-0.8 and Method II from 0.6-0.7.
Conclusions: Measuring the medial cuneiform to 2nd metatarsal joint space utilizing coronal WBCT imaging with the use of a protocol that localizes the exact location of the insertion of the Lisfranc ligament is reproducible. The method is simple to use and could potentially become a useful tool for clinical assessment of the Lisfranc joint. The limitations of this study involve only using four parameters for measurements, two in each coronal and axial view. Due to variability of midfoot morphology between individuals, further studies are needed to help obtain a normal value and improve detection of subtle Lisfranc injuries