title: Comparative study of the Orthofix and Pittsburgh frames for external fixation of unstable pelvic ring fractures.
abstract: We compared the mechanical performance of the Orthofix pelvic external fixator with that of the Pittsburgh triangular frame (PTF) on eight fresh-frozen cadaver pelves with experimentally created Malgaigne (double-vertical) fracture/dislocations. The pelves were quasi-statically loaded in longitudinal compression and loss of reduction (i.e., failure) was defined as 1.5 cm of diastasis at either of the fracture/dislocation sites. The Orthofix frame-pelvis complex (four 6-mm half-pins) was comparable to the PTF-pelvis complex (eight 5-mm half-pins) in terms of load to failure and overall stiffness, but was 4-7 times stiffer at lower load levels. Both frame-and-pin complexes deformed moderately at the pin-bone interface, but, while the PTF also showed moderate displacement between frame components, the Orthofix had almost no frame intercomponent motion.
authors.affiliation: Department of Orthopaedic Surgery, University of Iowa Hospitals and Clinics, Iowa City 52242.
authors.forename: A L
authors.initials: AL
authors.lastname: Bell
authors.forename: R A
authors.initials: RA
authors.lastname: Smith
authors.forename: T D
authors.initials: TD
authors.lastname: Brown
authors.forename: J V
authors.initials: JV
authors.lastname: Nepola
mesh_terms: D000328:Adult; D000368:Aged; D004867:Equipment Design; D005260:Female; D005592:Fracture Fixation / Q000295:instrumentation*; D005596:Fractures, Closed / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009984:Orthopedic Fixation Devices; D010384:Pelvic Bones / Q000293:injuries* / Q000503:physiopathology; D013314:Stress, Mechanical