title: Anterior cruciate ligament ganglion causing flexion restriction: a case report and review of literature.
abstract: Ganglion cysts originating from the anterior cruciate ligament (ACL) are uncommon. Often asymptomatic, they infrequently present with non-specific symptoms such as knee pain, stiffness, clicks, locking or restriction of knee extension. However, the patient we report presented with knee flexion restriction. A 37-year-old Chinese gentleman, with no history of knee trauma, presented with left knee pain. Left knee range of motion (ROM) was from 0 to 110 degrees. Magnetic resonance imaging (MRI) scan revealed a 1.5 cm × 3.3 cm × 1.7 cm cyst located in the intercondylar region arising from the ACL and extending predominantly posteriorly. Arthroscopy confirmed an intrasubstance ACL ganglion cyst, which was extending posteriorly. Complete excision of the cyst was performed. At 1-year follow-up, the patient regained knee flexion of 130 degrees. We describe one of the largest ACL ganglion cysts. Such cysts often extend anteriorly and impinge onto the roof of the intercondylar notch during knee extension, thus restricting extension. The restriction in knee motion in our patient was in flexion instead; this was because the cyst took an unusual course of extension predominantly in the posterior direction. Although rare, it must be included as a possible differential diagnosis when patients present with such knee symptoms.
authors.affiliation: 1 Department of Yong Loo Lin School of Medicine, National University of Singapore, Singapore ; 2 Department of Orthopaedic Surgery, Tan Tock Seng Hospital, Singapore.
authors.forename: Andrew Arjun
authors.initials: AA
authors.lastname: Sayampanathan
authors.affiliation: 1 Department of Yong Loo Lin School of Medicine, National University of Singapore, Singapore ; 2 Department of Orthopaedic Surgery, Tan Tock Seng Hospital, Singapore.
authors.forename: Thean Howe Bryan
authors.initials: TH
authors.lastname: Koh
authors.affiliation: 1 Department of Yong Loo Lin School of Medicine, National University of Singapore, Singapore ; 2 Department of Orthopaedic Surgery, Tan Tock Seng Hospital, Singapore.
authors.forename: Keng Thiam
authors.initials: KT
authors.lastname: Lee
keywords: Anterior cruciate ligament (ACL); flexion restriction; ganglion cyst