lumbosacral spondyloptosis , by definition , is more than 100% anterior displacement of the l5 vertebra with regard to the sacrum . it is also known as grade 5 spondylolisthesis.1 
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 3 it represents a rare type of injury and most of the time is a result of a high - energy trauma.4 
 5 this report describes our experience with a case of acute traumatic l5 spondyloptosis . a 28-year - old man presented with severe low back pain , numbness at the soles of feet , and bowel and bladder dysfunction . two days before admission , a tree trunk fell on his back while he was seated . the patient was transferred to the hospital near his house and was followed for 2 days with the treatment of analgesic medication . when he was transferred to our center , his physical examination was significant with tenderness of the posterior low lumbar area , wide ecchymosis in the lumbosacral area , and severe low back pain . neurologic examination revealed 5/5 motor strength of both lower extremities according to manual muscle testing and numbness at the soles of his feet . 2 ) , and magnetic resonance imaging suggested almost complete dural sac obstruction between l5 and s1 levels as well as disrupted disk space ( fig . magnetic resonance imaging showing complete dural sac obstruction between l5 and s1 levels and disrupted disk space . surgical treatment was chosen as the patient presented with severe low back pain in adjunct to neurologic deficit and unstable l5s1 segment due to spondyloptosis . a two - stage posterior - anterior procedure was performed . at the first stage , intraoperatively , a gap between l4 and s1 segments and fracture - dislocation of l5 inferior facets were observed . decompression of the dural sac and nerve roots was performed via laminectomy of l5 and inferior and superior parts of the laminae of l4 and s1 , respectively . posterior instrumentation from l4 to s1 was then performed , followed by reduction of the l5 segment . six days after the first stage , the patient underwent an anterior lumbar interbody fusion procedure trough a left paramedian approach . he has been pain - free for a year and has returned to work ( fig . ( a ) lateral and ( b ) anterior - posterior radiographs at postoperative month 6 . a pubmed search was performed by using the following keywords ; lumbosacral spondyloptosis , lumbosacral dislocation , and l5s1 traumatic dislocation . only nine reported cases of traumatic spondyloptosis ( table 1 ) could be found in the english literature . most of these cases ( six of nine ) were the result of motor vehicle accident or substantial falls . one case occurred following a grand mal epileptic seizure , one case resulted after a motor vehicle accident due to a tonic - clonic seizure , and one occurred following a landslide.4 
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 13 our case , to our knowledge , is the first case that occurred after a direct impact of an object ( tree trunk ) . abbreviations : asia , american spinal injury association ; nr , not reported . although there has been no biomechanical study to explain the pathomechanism of traumatic spondyloptosis , the injury tends to happen when a force is applied to the lumbar spine , especially when the pelvis and sacrum are in a fixed position.10 
 14 however , saiki et al reported in their review that hyperextension can lead to anterior lumbosacral dislocation if there is a preexisting spondylolytic lesion at l5.12 in our case , we believe that the mechanism of injury was a sudden posterior - to - anterior force applied by a big tree trunk . there have been different reports regarding the neurologic deficit caused by traumatic spondyloptosis including complete and incomplete neurologic deficit . of the nine cases with l5s1 spondyloptosis , three had complete and four had incomplete neurologic injury , whereas two cases that resulted from seizures were neurologically intact.4 
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 15 in our case there was no motor deficit at the extremities but urinary and fecal incontinence as well as numbness in the sole of both feet . after a period of 6 months of physical therapy , his bowel and bladder incontinence completely resolved . the reason for this , in our opinion , may be a transient neuropraxia of s2s5 nerve roots . surgery aims to reduce , decompress , stabilize , and fuse the spondyloptotic segment.4 
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 13 as decompression was necessary in our case ( due to neurologic deficit ) , we preferred to start with a posterior approach to decompress , reduce , and fix the unstable segment . to enhance fusion and stability , we then performed an anterior interbody fusion . in conclusion , traumatic spondyloptosis at the lumbosacral junction is a rare ailment that should be suspected in cases of high , direct , and posterior impact on the low lumbar area , and surgical treatment should be the standard choice of care .
study design  case report and review of the literature . 
 objective  to report a case of traumatic l5s1 spondyloptosis and review the literature . 
 method  a 28-year - old man presented with severe low back pain , numbness at the soles of feet , and bowel and bladder dysfunction . 
 two days before admission , a tree trunk fell on his back while he was seated . 
 a two - stage posterior - anterior procedure was performed . at the first stage , posterior decompression , reduction , and fusion with instrumentation 
 were performed . at the second stage , which was performed 6 days after the first stage , the patient underwent anterior lumbar interbody fusion . 
 the patient received physical therapy 1  week after the second stage . 
 results  the patient 's numbness improved immediately after the first posterior surgery . his fecal and urinary incontinence improved 6 months after discharge . 
 he has been pain - free for a year and has returned to work . 
 conclusion  a pubmed search was performed using the following keywords : lumbosacral spondyloptosis , lumbosacral dislocation , and l5s1 traumatic dislocation . 
 the search returned only nine reported cases of traumatic spondyloptosis . 
 traumatic spondyloptosis at the lumbosacral junction is a rare ailment that should be suspected in cases of high , direct , and posterior impact on the low lumbar area , and surgical treatment should be the standard choice of care .