A Case Report of a Rare Presentation of Semimembranosus Tibial Plateau Avulsion: The Bony Ramp Lesion

Abstract

Background: Tibial plateau posteromedial rim avulsions by semimembranosus tendon are a rare entity reported in a few studies so far with controversial mechanism. They are reported to accompany anterior cruciate ligament or meniscal injuries with their main fracture planes usually oriented coronally.

Case presentation: The patients was a 52-year-old male with a hyperextension-valgus tibial plateau fracture. There was a compression fracture of the lateral and an avulsion fracture of the posteromedial plateau. However, no soft-tissue injuries were detected in our patient. The avulsed fragment was oriented axially and covered by the medial meniscal posterior horn, creating the pattern of a longitudinal tear in a meniscal ramp lesion, but actually without any soft-tissue injuries. The fragment was fixated using tension band wiring technique with two Kirschner wires and one cancellous screw to approximate it to the tibia. Radiological and functional outcomes were excellent at 12-month follow-up

Conclusions: This fracture pattern merits special attention due to its unusual presentation, causing the meniscal posterior horn to get separated from the articular surface. “Bony ramp lesion” best describes the simultaneous separation of posterior horn of medial meniscus and its underlying bony fragment; without soft-tissue injuries of a real medial meniscal ramp lesion.