Fig. 4

Types of the ligamentum mucosum identified. a Separate type. The ligament is a single and running from the ICN to the IPFP. b Vertical septum type. The ligament’s posterior surface is in direct contact with the ACL throughout its length. c Absent type. There is no ligament to obstruct the view of the ACL. d Fenestra type. The ligament is attached to the ACL posteriorly, with fenestrae between the two. E–f Split type, anterior and medial view. The ligament is made up of two distinct, separate and parallel bands, one sitting between its anterior counterpart and the ACL. Abbreviations: ICN Intercondylar notch. IPFP Infrapatellar fat pad. TG Trochlear groove. LM Ligamentum mucosum. MTP Medial tibial plateau. LTP Lateral tibial plateau. ACL Anterior cruciate ligament. MC Medial condyle. LC Lateral condyle