Bone marrow lesions in the knee are associated with meniscal lesions and cartilage pathologies according to the six-letter system

Abstract

Purpose This study aims to ind a correlation between bone marrow lesions (BMLs) in knee MRI and pathologies of joint structures. In addition, according to the six-letter system classiication, the authors analyzed a potential association between the area afected by BMLs and the speciic type of joint lesion. Methods The authors screened all the knee MRIs performed in the investigation center between 2017 and 2018 to identify the presence of BMLs. The lesions were then categorized following the "six-letter system". The authors searched the presence of associated meniscal, chondral or ligamentous lesions. Finally, the authors researched a correlation between the lesion type described by the six-letter system classiication and the associated lesions. Results MRI exams of 4000 patients were studied, identifying 666 BMLs. The associated lesions were collected for all patients, resulting in an overall prevalence of related lesions in almost 90% of patients. The authors found a statistical signiicance for type TLD (Tibia-Lateral-Articular) and ACL rupture. The study suggests a strong positive correlation between type E (Edge) and meniscal fracture or extrusion. Conclusion BMLs in the knee are associated in 90% of cases with a radiological sign of related injury to the joint structures. The six-letter system of BMLs type TLD can be considered a sign of ACL rupture and type E as a high suspicious sign for meniscal extrusion. Those very typical BML patterns can help the clinician in the diagnosis of ACL tears and meniscal extrusion. Furthermore, the presence of a BML must be, for the clinician, a high suspicious sign of joint-related injuries. Level of evidence Level 1.

The meniscal extrusion index is a reliable indirect sign of different meniscal lesion patterns: a classification based on percentage of meniscal extrusion

“…The loss of functional capacity in an extruded meniscus can contribute to the progressive deterioration of osteoarthritis and the development of bone edema syndrome over time [ 2 , 3 , 13 ].…”