a 20-year - old man under the influence of alcohol was in a car that rolled over ; he received initial treatment in a community hospital where he was diagnosed with abdominal trauma that did not require any surgical treatment . a spinal cord injury with traumatic dislocation of l4l5 was diagnosed and referred to our tertiary care orthopedic unit 10 days after the accident . the patient had ecchymosis of the lumbosacral region , motor strength grade 2/5 in the proximal lower - extremity muscle groups ( l1l3 myotomes ) and 0/5 strength distally ( l4s1 myotomes ) , incontinence of sphincters , absence of rectal tone , and loss of perianal sensation . x - rays and computed tomography ( ct ) scan revealed a fracture of the l4 vertebral body with complete posterior dislocation of l4 to l5 vertebral body with maintenance of the anteroinferior corner of the l4 vertebral body in place ( figs . 1 , 2 , and 3 ) . 
 preoperative computed tomography scan , sagittal view , showing complete l4l5 posterior dislocation . magnetic resonance imaging , axial view , showing the l4 vertebral body posterior to l5 . 
 magnetic resonance imaging , sagittal view , showing integrity of the intervertebral disc l4l5 . because of the delay in surgical treatment , a halo - femoral traction was placed for 3 days before surgery to stabilize and to attempt reduction without achieving any favorable outcome . at the time of surgery , the patient underwent posterior reduction with pedicle screw and rod - augmented fusion from l3 to s1 . reduction maneuvers included initial lengthening between l3l4 and s1 screws , which allowed access to the l5 pedicle ; l5 pedicle fixation ; l3l4 and l5s1 lengthening ; l4 laminectomy with access to the l4l5 disc space ; placement of a cob spinal elevator on the l4l5 space , which served as a lever to achieve reduction in the coronal and sagittal plane ; and finally a two - rod construct with a cross - link with posterolateral fusion enhanced with an allograft from l3 to s1 . during surgery , there was no evidence of dural tear or cerebrospinal fluid leak . the muscular strength reached 5/5 in proximal lower - extremities muscle groups ( l1l3 myotomes ) and 0/5 distally ( l4s1 myotomes ) . function of the sphincters and perianal sensation fully recovered . at 1-year follow - up , plain radiograph and ct scan showed good alignment and progressive maturation of his fusion procedure ( figs . 4 , 5 , and 6 ) . 
 one - year follow - up postoperative supine computed tomography scout image showing anteroposterior view of the internal fixation from l3 to s1 . one - year follow - up lateral view x - ray showing appropriate reduction and internal fixation . 
 computed tomography scan reconstruction at 1-year follow - up , showing appropriate fusion . a 20-year - old man under the influence of alcohol was in a car that rolled over ; he received initial treatment in a community hospital where he was diagnosed with abdominal trauma that did not require any surgical treatment . a spinal cord injury with traumatic dislocation of l4l5 was diagnosed and referred to our tertiary care orthopedic unit 10 days after the accident . the patient had ecchymosis of the lumbosacral region , motor strength grade 2/5 in the proximal lower - extremity muscle groups ( l1l3 myotomes ) and 0/5 strength distally ( l4s1 myotomes ) , incontinence of sphincters , absence of rectal tone , and loss of perianal sensation . x - rays and computed tomography ( ct ) scan revealed a fracture of the l4 vertebral body with complete posterior dislocation of l4 to l5 vertebral body with maintenance of the anteroinferior corner of the l4 vertebral body in place ( figs . 1 , 2 , and 3 ) . 
 preoperative computed tomography scan , sagittal view , showing complete l4l5 posterior dislocation . 
 magnetic resonance imaging , axial view , showing the l4 vertebral body posterior to l5 . 
 magnetic resonance imaging , sagittal view , showing integrity of the intervertebral disc l4l5 . because of the delay in surgical treatment , a halo - femoral traction was placed for 3 days before surgery to stabilize and to attempt reduction without achieving any favorable outcome . at the time of surgery , the patient underwent posterior reduction with pedicle screw and rod - augmented fusion from l3 to s1 . reduction maneuvers included initial lengthening between l3l4 and s1 screws , which allowed access to the l5 pedicle ; l5 pedicle fixation ; l3l4 and l5s1 lengthening ; l4 laminectomy with access to the l4l5 disc space ; placement of a cob spinal elevator on the l4l5 space , which served as a lever to achieve reduction in the coronal and sagittal plane ; and finally a two - rod construct with a cross - link with posterolateral fusion enhanced with an allograft from l3 to s1 . during surgery , there was no evidence of dural tear or cerebrospinal fluid leak . the muscular strength reached 5/5 in proximal lower - extremities muscle groups ( l1l3 myotomes ) and 0/5 distally ( l4s1 myotomes ) . function of the sphincters and perianal sensation fully recovered . at 1-year follow - up , plain radiograph and ct scan showed good alignment and progressive maturation of his fusion procedure ( figs . 4 , 5 , and 6 ) . one - year follow - up postoperative supine computed tomography scout image showing anteroposterior view of the internal fixation from l3 to s1 . one - year follow - up lateral view x - ray showing appropriate reduction and internal fixation . 
 computed tomography scan reconstruction at 1-year follow - up , showing appropriate fusion . high - energy force is required to create a complete fracture - dislocation of the lumbar spine . to the best of our knowledge , there are only two cases of traumatic retrolisthesis previously reported in the english literature ; a direct shearing force at the lower lumbar area was described as the mechanism causing the dislocation in both cases . in the first case , abdel - fattah and rizk7 described a total posterior dislocation of l4 vertebral body behind l5 ; surgical treatment consisted of reduction and internal fixation with a sacral rod and two harrington rods . good reduction was obtained immediately ; however , loss of reduction was observed at 2 months ' follow - up , and implants were removed at 7 months ' follow - up . the authors reported that the patient was asymptomatic , neurologically intact , and solidly fused . the other case was reported by ahmed8 et al , who described a traumatic retrolisthesis of l4 vertebra without complete displacement of the vertebral body ; posterior reduction and internal fixation with pedicle screws and rods from l3 to l5 and discectomy were performed , and interbody fusion with a mesh cage was achieved . full motor and sensory function was reported at 2 years ' follow - up . in our case , we did not use any anterior support but a cage in the l4l5 interbody space may have been helpful in lordosis restoration and to provide stability . unlike the two previous reports , our patient only recovered muscular strength in the levels above the lesion . no motor function recovered from l4 or lower levels . at the time of the surgical procedure , a complete section of the l4 roots was observed bilaterally , making this neurological outcome predictable . surgical treatment was indicated because the three - column disruption makes this lesion highly unstable . traumatic posterior fracture dislocation of l4l5 is rare and usually results from a high - energy trauma . the patient was successfully treated with open reduction , decompression , internal fixation with transpedicular screws , and posterolateral fusion .
study design  case report . 
 objective  the diagnosis and surgical management of a patient with traumatic bilateral posterior dislocation of l4l5 is presented with a thorough review of the existing literature . 
 summary of background data  traumatic dislocation of l4l5 has been reported in the english literature in only five cases ; of these , only two were retrolisthesis . 
 methods  a 20-year - old patient was involved in a high - energy vehicular accident and presented with back pain and inability to ambulate . 
 neurological assessment showed motor strength grade 2/5 in the proximal lower - extremity muscle groups ( l1l3 myotomes ) and 0/5 strength distally ( l4s1 myotomes ) ; in addition , incontinence of sphincters was found . 
 x - rays and computed tomography ( ct ) scan revealed a three - column ligamentous injury with posterior fracture - dislocation of the l4 vertebral body with complete posterior displacement of l4 to l5 vertebral body . 
 the patient underwent posterior approach with reduction , transpedicular fixation , and posterolateral fusion with autologous bone graft . 
 results  at 1-year follow - up , the patient had recovered muscular strength in proximal lower - extremities muscle groups , sphincter function had fully recovered , and he was able to ambulate with crutches . 
 there was no recovery of distal extremity sensorimotor function . 
 plain radiograph and ct scan showed good alignment and progressive maturation of his fusion procedure . 
 conclusion  traumatic retrolisthesis of l4l5 is a high - energy unstable fracture ; reduction of the dislocation is challenging because of the heavy forces acting in the lower lumbar spine . 
 instrumented fusion restores alignment and maintains segmental stability .