title: Modular ulnar head decoupling force: case report.
abstract: Cobalt-chrome modular distal ulnar head replacement arthroplasty is a surgical option to restore stability to the distal radioulnar joint rendered unstable by hemi-resection arthroplasty or a total resection arthroplasty. However, the revision of dislocated modular cobalt-chrome ulnar head implants may pose an important intraoperative challenge. The Morse-taper disassembly force of modular ulnar head implants is not available in the current published literature. We present a case in which tremendous difficulty was encountered while revising a dislocated modular cobalt-chrome distal ulnar head implant. The mean Morse-taper disassembly force of the retrieved modular cobalt-chrome implant was 2958 N +/- 1272. At nearly 4.5 times the average body weight, the modular ulnar head Morse-taper disassembly strength presented a formidable force to overcome intraoperatively.
authors.affiliation: REMI Sciences Inc., Pinnacle Health Hand Center, Mechanicsburg, PA, USA. Snaidu3555@comcast.net
authors.forename: Sanjiv H
authors.initials: SH
authors.lastname: Naidu
authors.forename: Alex
authors.initials: A
authors.lastname: Radin
mesh_terms: D000328:Adult; D019643:Arthroplasty, Replacement; D001696:Biomechanical Phenomena; D002858:Chromium Alloys; D020878:Device Removal; D005260:Female; D006801:Humans; D004204:Joint Dislocations / Q000000981:diagnostic imaging; D007595:Joint Prosthesis; D010003:Osteoarthritis / Q000601:surgery; D011859:Radiography; D012086:Reoperation; D014457:Ulna / Q000601:surgery*; D014955:Wrist Joint / Q000000981:diagnostic imaging / Q000601:surgery*
chemical_list: D002858:Chromium Alloys