title: Posterior dislocation of the hinge-post extension in a rotating hinge total knee prosthesis.
abstract: The rotating hinge knee prosthesis is a popular intervention in patients lacking stability with highly constrained total knee arthroplasty. Despite improvements in design, nonmechanical and mechanical complications continue to be a problem. Dislocation of the hinge has been widely described, mainly due to the component fracture. Few reports describe isolated dislocation of the rotating stem. We report a case of isolated disengagement of the rotating hinge mechanism, due to severe flexion gap imbalance, leading to subsequent posterior dislocation of the hinge and anterior knee dislocation, in a patient with a history of multiple total knee arthroplasty revisions. This case suggests the importance of the soft tissue balancing, the adequate patellar tracking, and use of a long cylindrical, minimally tapered rotating stem in hinge arthroplasty to minimize hinge dislocation.
authors.affiliation: Department of Orthopaedic Surgery, Joint Replacement Service, University of California Irvine Medical Center, 101 The City Drive South, Pavilion III, Building 29, Orange, CA 92868, USA.
authors.forename: Givenchy
authors.initials: G
authors.lastname: Manzano
authors.forename: Ran
authors.initials: R
authors.lastname: Schwarzkopf