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Mechanism of Injury in Ramp Lesion: Letter to the Editor

Dear Editor: We read the article by Thaunat et al, ‘‘Ramp Lesion Subtypes: Prevalence, Imaging, and Arthroscopic Findings in 2156 Anterior Cruciate Ligament Reconstructions,’’ with interest and would like to congratulate the authors on the excellent work on this topic of ‘‘ramp lesions’’ of the meniscus. We want to add some more insight to this topic to enlighten the readers. We have recently described a rare pattern of ramp lesion. Here, the ramp lesion was associated with a fracture of the rim of the posterior medial tibia, avulsion of the posterior horn of the medial meniscus, and a radial tear of the junction of the body and posterior horn. In effect, this lesion had amputated the posterior meniscus. We would value the opinion of the authors on this pattern of a ramp lesion. The authors have presented 2 mechanisms of theories for the ramp lesions. While we accept that the following may not be the case in all the injuries, we believe that the forces are crushing in nature, as we noticed in our report. This view is supported by the fact that several authors have reported bone contusion of the posterior rim of the medial tibia in association with ramp lesions. We believe that the rim fracture in our case was an extension of this contusion. Segmental amputation of the meniscus and the displacement of remnants into the ramp lesion further strengthen this hypothesis. The forces causing this would be directed posterior (as seen in the ‘‘door stopper’’ mechanism of the meniscus during anterior subluxation in anterior cruciate ligament [ACL] injury) along with a heavy component of axial loading causing the fracture. With decreasing magnitude of axial load, a spectrum of ramp lesions with a bone contusion, followed by lesions without a contusion, may be seen. There could be an interplay of axial and posterior compressive forces causing the various injuries that we are seeing, rather than pulling forces from the back. We firmly believe that the compressive forces are responsible for the rim fractures associated with atypical ramp lesions. On the contrary, avulsion forces account for clean breaks perpendicular to the force applied. It is known that the axial load is one of the major forces in the mechanisms causing ACL injuries, which further corroborates the above explanation. The authors reported that 48.4% of the 38 (type 3) ramp lesions had bone contusion in the posterior rim of the medial tibia. We would like to know if there were any associated bone bruises in the adjacent posterior or middle medial femoral condyle. If these were present, then it seems to be due to an impaction type of injury. Perhaps a separate study looking into this aspect would be beneficial, and the authors’ extensive experience on this subject would be very useful in solving this conundrum. We believe further studies on the mechanism of ramp lesion are needed, and inclusion of the mechanism within the classification would be beneficial for diagnosing, understanding, and managing these challenging cases.