Background: The presence of lumbosacral transitional vertebrae (LSTV) may affect the variation of the termination level of conus medullaris (TLCM). However, there have been few studies examining the association between the distribution of the TLCM and LSTV, especially in young patients. The purpose of this investigation was therefore to assess the relationship between the TLCM and LSTV in young patients.
Methods: A total of 379 patients with lumbar herniated disks were included in this study. There were 249 males and 130 females, with a mean age of 31 years (range 15-44). The patients were classified into three groups: (1) L4/TV group (7 %): 28 patients with sacralization of the fifth lumbar vertebrae; (2) L5/TV group (11 %): 41 patients with lumbarization of the sacrum; and, (3) normal group (82 %): 310 patients without LSTV. TLCM was assessed using MRI.
Results: The median TLCM of the normal, L4/TV and L5/TV groups was the middle third of L1, the upper third of L1 and the lower third of L1, respectively. The TLCM in the L4/TV group was significantly higher than that observed in the normal group (p < 0.001), while that in the L5/TV group was significantly lower than observed in the normal group (p < 0.001).
Conclusions: The presence of LSTV affected the variation of the TLCM. Therefore, the distribution of the TLCM with or without lumbosacral TV may help clinicians to identify the neurological discrepancies observed among neurologic injuries at the thoracolumbar junction.