European Journal of Radiology Extra 68 (2008) 33–35 Anomalous insertion of anterior cruciate ligament band into the transverse ligament Fernando Ruiz Santiago a,* , María del Mar Castellano García a , Juan Miguel Tristán Fernández a , Juan Tercedor Sánchez b a Department of Radiology, Hospital of Traumatology (Ciudad Sanitaria Virgen de las Nieves), Carretera de Jaen SN, 18013 Granada, Spain b Department of Traumatology, Hospital of Traumatology (Ciudad Sanitaria Virgen de las Nieves), Carretera de Jaen SN, 18013 Granada, Spain Received 29 March 2008; received in revised form 3 May 2008; accepted 2 June 2008 Abstract We report an unusual case of bilateral anomalous insertion of the anterior cruciate ligament (ACL) band into the transverse ligament. Although many insertion abnormalities of ACL have been described, this is, to our knowledge, the first magnetic resonance case reporting this unusual place of insertion. © 2008 Elsevier Ireland Ltd. All rights reserved. Keywords: Anterior cruciate ligament; Anterior cruciate ligament abnormalities; Anteromedial bundle; Posterolateral bundle; Anatomy; Magnetic resonance imaging 1. Introduction There are few reports regarding congenital abnormalities of the anterior cruciate ligament and most of them are referring to its absence or hypoplasia [1]. In this paper we report a bilateral case of abnormal insertion of anterior cruciate ligament (ACL) band into the transverse ligament. We review the embryology in order to explain this abnormality. 2. Case report A 45-year-old female patient was sent for MRI examination of the left knee because of pain during last 3 months in the inter- nal compartment, increased during every day normal activity. Physical exam and meniscal test lead to suspicion of internal meniscus tear. No instability was demonstrated. A horizontal cleavage tear was found at MRI exam (Fig. 1). The anterior cruciate ligament (ACL) band was shown to insert directly into a strong transverse geniculate ligament (Fig. 2). Then, the con- tralateral knee was also scanned. In this knee, a medial meniscus menicestomy was performed a year ago, in other institution. The MRI showed degenerative changes in both menisci with- * Corresponding author at: C-Julio Verne 8, 7B, 18003 Granada, Spain. E-mail addresses: ferruizsan@terra.es, ferusan@ono.com (F. Ruiz Santiago). out evidence of a new tear, and the same ACL abnormality with the anterior ACL band inserting into the transverse liga- ment. Although this finding was substantiated in the arthroscopy report, images could not be obtained. The used MRI system was a MR Max of 0.5 T (GE Medical System). The used sequences were sagittal T1 (SE, TE: 25; TR: 600) and T2* (GE, TE: 20; TR: 600 ms, flip angle: 30), coronal T1 (SE, TE: 25; TR: 600) and axial T2*(GE, TE: 20; TR: 600 ms, flip angle: 30) weighted images. 3. Discussion The tibial attachment site of the ACL is broad-based, located in a fossa anterior and lateral to the medial tibial spine. Although some authors describe the ACL as one entity [2] or as a struc- ture consisting of three bundles in macroscopic evaluation [3], the double bundle model of ACL is more widely accepted due to its superior concordance with the variable tension patterns of ACL anatomy [4]. In the sagittal plane, the posterior band of the ACL attaches to the posterior third of the anterior intercondy- lar area on the upward intercondylar eminence slope, while the distal insertion of the anterior band of the ACL is normally located beneath the transverse ligament, although some fibers may expand to the anterior horn of the lateral meniscus [5]. The transverse ligament of the knee lies between the anterior horns of the menisci and is not a constant feature in all individuals, 1571-4675/$ – see front matter © 2008 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejrex.2008.06.001