title: Ultrasound evaluation of bursae: anatomy and pathological appearances.
abstract: A bursa is an extra-articular sac that may communicate with a joint and functions to decrease friction between tendons and either bone or skin. Bursae can be classified as native and non-native (adventitious) bursae. The native bursae are lined with a synovial membrane and occur at predictable anatomical sites; knowledge of these normal structures can help distinguish them from other pathological entities. An adventitious bursa can form at sites of friction rather than at predictable anatomical sites, but otherwise have imaging features similar to native bursae. Bursal distention can occur from many pathological processes, most commonly resulting from chronic overuse injury. When imaging bursal pathological conditions, there is often an overlap of imaging findings, regardless of the cause. In general, ultrasound of a distended bursa reveals a fluid collection with either simple anechoic or more complex hypoechoic fluid. Bursal distention is characteristically unilocular and compressible, unlike other structures such as ganglion cysts, which are usually multilocular and non-compressible. This article reviews the anatomical locations of common bursae and shows pathological examples using ultrasound. Knowledge of typical locations and imaging appearances of bursae can aid in narrowing the differential diagnosis and guiding further management and treatment decisions.
authors.affiliation: Department of Diagnostic and Therapeutic Radiology, Faculty of Medicine Ramathibodi Hospital, Mahidol University, 270 Rama VI Road, Rachathewi, Bangkok, 10400, Thailand.
authors.forename: Thumanoon
authors.initials: T
authors.lastname: Ruangchaijatuporn
authors.affiliation: Department of Radiology, University of Michigan, 1500 East Medical Center Drive, TC 2852B, Ann Arbor, MI, 48109, USA. kgaetke@umich.edu.
authors.forename: Kara
authors.initials: K
authors.lastname: Gaetke-Udager
authors.affiliation: Department of Radiology, University of Michigan, 1500 East Medical Center Drive, TC 2852B, Ann Arbor, MI, 48109, USA.
authors.forename: Jon A
authors.initials: JA
authors.lastname: Jacobson
authors.affiliation: Department of Radiology, University of Michigan, 1500 East Medical Center Drive, TC 2852B, Ann Arbor, MI, 48109, USA.
authors.forename: Corrie M
authors.initials: CM
authors.lastname: Yablon
authors.affiliation: Department of Radiology, University of Michigan, 1500 East Medical Center Drive, TC 2852B, Ann Arbor, MI, 48109, USA.
authors.forename: Yoav
authors.initials: Y
authors.lastname: Morag
mesh_terms: D002061:Bursa, Synovial / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D002062:Bursitis / Q000000981:diagnostic imaging*; D006801:Humans; D014463:Ultrasonography / Q000379:methods*
keywords: Bursa; Bursae; Bursitis; Recess; Ultrasound