RESUMO
BACKGROUND: We investigated the causes of failure of the Allis manoeuvre for posterior hip dislocations with an associated Pipkin type I femoral head fractures. The effectiveness of a modified Allis manoeuvre was also evaluated. METHODS: From January 2013 to December 2016, we enrolled five patients with a posterior hip dislocation associated by a Pipkin type I femoral head fracture who were treated initially with the Allis manoeuvre that subsequently failed. Radiographic evaluations were performed to determine the cause of failure, and then a modified Allis manoeuvre was performed. During this procedure, the hip and knee joints of the injured lower limb were both flexed to 90°, and the leg was pulled posteriorly following an upward force to reduce the dislocation. Reduction was assessed by radiographic evaluation. RESULTS: In all patients, the fractured femoral head was incarcerated on the superior edge of the posterior rim of the acetabulum, resulting in failure of the conventional Allis manoeuvre. Satisfactory reduction was achieved with a modified Allis manoeuvre. The mean follow-up duration was 31 months. The femoral head fracture healed after four months on average. The mean Harris score was 91 at the final follow-up. Re-dislocation or femoral head necrosis was not observed. CONCLUSIONS: For posterior hip dislocations associated with a Pipkin type I femoral head fracture, failed reduction is often caused by incarceration of the fractured femoral head on the superior edge of the posterior rim of the acetabulum. The modified Allis manoeuvre can effectively reduce the combined injury in a closed fashion.