SUMMARY
The aims of the study were to describe our experience with dislocations after rotating hinge total knee arthroplasty (RHTKA) in a consecutive prospective large series, its occurrence rate, causative mechanisms and to perform a literature review. In total, six dislocations were observed in 303 RHTKA procedures (2 primary and 4 revision) at a mean of 10 months after surgery. This resulted in a 2% dislocation rate, which is lower than the 3.1% cumulative rate reported in literature. Men and women were distributed equally, most of them (83%) were severely obese (BMI 34-52).The main mechanism of hinge dislocation was forced knee flexion with concomitant extensor mechanism insufficiency (four cases, 66.6%). The second cause was unscrewing of the locking pin (two cases, 33.3%).Improvements in the hinge design, as to better secure the locking pin to prevent unscrewing, seem advisable. A fixed hinge implant may be more optimal than RHTKA when extensor mechanism is deficient and its reconstruction is not possible or has failed.