title: Posterosuperior glenoid internal impingement of the shoulder in the overhead athlete: pathogenesis, clinical features and MR imaging findings.
abstract: Posterosuperior glenoid internal impingement (PGII) is an impingement syndrome of the shoulder that is most commonly seen in the throwing or overhead athlete. The supraspinatus can be normally compressed or impinged between the greater tuberosity and the posterosuperior labrum in the abduction and external rotation position. However, repetitive throwing and biomechanical abnormalities may lead to the intensification of this contact and to the clinical and pathological picture of PGII. The injured athlete usually complains of poor throwing performance and pain located in the posterosuperior aspect of the shoulder. Two main theories regarding the aetiology of PGII have been postulated with differing initial mechanisms. The MRI features of PGII have been described and include supraspinatus and anterior infraspinatus partial undersurface tears, bony changes at the humeral head and labral pathology, including a variation of the type II superior labrum from anterior to posterior lesion. This pictorial essay aims to present cases illustrating the pathophysiology, clinical features and recently described MRI findings, and discuss some of the MR protocol considerations.
authors.affiliation: Prince of Wales Hospital, Sydney, New South Wales, Australia.
authors.forename: Chris Kon
authors.initials: CK
authors.lastname: Fessa
authors.forename: Anthony
authors.initials: A
authors.lastname: Peduto
authors.forename: James
authors.initials: J
authors.lastname: Linklater
authors.forename: Phillip
authors.initials: P
authors.lastname: Tirman
mesh_terms: D000293:Adolescent; D001265:Athletic Injuries / Q000473:pathology*; D012090:Cumulative Trauma Disorders / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D019534:Shoulder Impingement Syndrome / Q000473:pathology*; D000070599:Shoulder Injuries; D012785:Shoulder Joint / Q000473:pathology*; D055815:Young Adult
keywords: GIRD; MRI; MRI arthrography; anterior instability; glenohumeral internal rotation deficit; internal impingement