title: Rotary subluxation of the metacarpophalangeal thumb joint: a case report.
abstract: Irreducible rotary subluxation of the metacarpophalangeal joint (MCPJ) of the thumb is a rare entity. Open reduction is indicated when signs of irreducibility are seen on the radiographs. We present one such case caused by displacement of the sesamoid bone into the intercondylar notch of the first metacarpal bone. A 35-year-old woman sustained a twisting injury to her right thumb by pronating and hyperextending it while attempting to retrieve things that she had dropped into a basin conduit. True lateral radiographs showed rotary subluxation of the thumb MCPJ, a sesamoid bone overlapping with the metacarpal head, and loss of the subsesamoid joint space and an incongruent MCPJ on full flexion. A high level of clinical suspicion is needed to diagnose this rare entity.
authors.affiliation: Department of Orthopaedics and Traumatology, Kwong Wah Hospital, Hong Kong. drandycheng@yahoo.com.hk
authors.forename: Sze-chung
authors.initials: SC
authors.lastname: Cheng
authors.forename: Chi-hung
authors.initials: CH
authors.lastname: Yen
authors.forename: Wai-lam
authors.initials: WL
authors.lastname: Chan
authors.forename: Wing-cheung
authors.initials: WC
authors.lastname: Wong
authors.forename: Kan-hing
authors.initials: KH
authors.lastname: Mak
mesh_terms: D000328:Adult; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008662:Metacarpophalangeal Joint / Q000000981:diagnostic imaging / Q000293:injuries* / Q000601:surgery*; D011859:Radiography; D013165:Splints; D013933:Thumb / Q000000981:diagnostic imaging / Q000293:injuries* / Q000601:surgery*