PURPOSE

Lumbosacral transitional vertebra (LSTV) are a common anatomical variant of the lumbosacral junction that has been associated with various spinal disorders. However, no prior studies have examined the relationship between LSTV and lumbar spondylolysis. Therefore, the aim of this study was to elucidate the prevalence of LSTV and assess its impact on the affected spinal level and bone union rate in patients with lumbar spondylolysis.

METHODS

This study retrospectively analyzed data from 346 patients (270 boys) aged ≤ 18 years diagnosed with lumbar spondylolysis between January 2012 and December 202. The affected spinal level was assessed in all 346 patients. Bone union was evaluated in 284 patients with very early, early, or progressive lesions who received conservative treatment. LSTV was assessed using the Castellvi classification, and patients were categorized into the LSTV and control groups based on the presence and absence of LSTV, respectively. Statistical analyses were performed to compare the distribution of affected spinal levels and bone union rates between groups.

RESULTS

Herein, the prevalence of LSTV in patients with lumbar spondylolysis was 21.1%. The incidence of spondylolysis at L3 and L4 was significantly higher in the LSTV group (L3: 20.5%, L4: 43.8%, and L5: 35.6%) than in the control group (L3: 4.8%, L4: 27.5%, and L5: 67.8%). No significant differences in bone union rates were observed between the two groups (LSTV: 100%, 94.8%, and 47.1%; control: 94.5%, 92.3%, and 49.5% in the very early, early, and progressive stages, respectively).

CONCLUSION

In patients with LSTV, spondylolysis is more likely to occur at L4 or a level more cranial than L5. However, the presence of the LSTV does not significantly affect the bone union rate.