title: Traumatic anterior lumbosacral dislocation caused by hyperextension mechanism in preexisting L5 spondylolysis: a case report and a review of literature.
abstract: Of many reports referring to injury mechanism in anterior lumbosacral dislocation, there were none concerning hyperextension mechanism. We report a case of a 46-year-old man with preexisting L5 spondylolysis sustaining traumatic complete anterior lumbosacral dislocation. The operative findings, together with the radiologic findings, strongly suggested that the dislocation occurred by hyperextension mechanism. Open reduction was done by applying force of distraction with flexion using a rod and screw system, followed by the internal fixation from the L3 to S1 vertebrae and the postero-superior iliac spine. The lumbosacral dislocation was reduced to 77%. At the follow-up at 5 years after surgery, bony union was obtained and the patient could move with a wheelchair although the neurologic deficit in lower extremities observed preoperatively did not recover. Preexisting L5 spondylolysis was considered to increase the potential for anterior lumbosacral dislocation by additional force of compression with hyperextension. Posterior instrumentation using a rod and screw system was considered a useful method for reduction, decompression, stabilization, and fusion.
authors.affiliation: Department of Orthopaedic Surgery, Saitama Medical Center, Saitama Medical School, Kawagoe, Saitama, Japan. saiky@proof.ocn.ne.jp
authors.forename: Kunio
authors.initials: K
authors.lastname: Saiki
authors.forename: Shigeru
authors.initials: S
authors.lastname: Hirabayashi
authors.forename: Hiroya
authors.initials: H
authors.lastname: Sakai
authors.forename: Kouichi
authors.initials: K
authors.lastname: Inokuchi
mesh_terms: D006801:Humans; D004204:Joint Dislocations / Q000209:etiology* / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000293:injuries / Q000601:surgery; D008161:Lumbosacral Region / Q000293:injuries / Q000601:surgery; D008297:Male; D008875:Middle Aged; D013123:Spinal Fusion; D013169:Spondylolysis / Q000150:complications* / Q000601:surgery*; D016896:Treatment Outcome; D021801:Zygapophyseal Joint / Q000293:injuries* / Q000601:surgery*