The clinical importance of lumbosacral transitional vertebra in patients with adolescent idiopathic scoliosis.

STUDY DESIGN

Retrospective review of radiographs.

OBJECTIVE

The objective of this study was to (1) determine the prevalence of lumbosacral transitional vertebra (LSTV) with computed tomography (CT) and (2) correlate LSTV presence with lumbar disc degeneration at each level by magnetic resonance imaging.

SUMMARY OF BACKGROUND DATA

LSTV is a frequently observed abnormality. Although its prevalence in patients with adolescent idiopathic scoliosis (AIS) has been shown, no studies have yet examined the clinical importance of LSTV in patients with AIS.

METHODS

This study included 385 consecutive patients who underwent surgery for AIS at a single center. Plain radiographs and CT scans were used to detect LSTV. Disc degeneration was analyzed at the L3-4, L4-5, and L5-S1 disc levels with magnetic resonance imaging. The difference in disc degeneration at each level by the presence of LSTV was also analyzed. The effect of lumbar curve type on the disc degeneration of each level was then determined. To minimize confounding factors, logistic regression analysis was performed.

RESULTS

The overall prevalence of LSTV in patients with AIS confirmed by CT scans was 12.2% (47/385). The proportion of grade II or more disc degeneration at the L4-5 level was higher in the LSTV(+) group than in the LSTV(-) group (29.8% vs.19.2%) although it was not statistically significant (P = 0.093). Large lumbar curves showed a positive correlation with disc degeneration at the L5-S1 level (P = 0.022).

CONCLUSION

The prevalence of LSTV in patients with AIS was 12.2%. A trend of early degeneration in L4-5 level discs was found in patients with AIS with LSTV although it was not statistically confirmed. Disc degeneration at the L5-S1 level is related to a large lumbar curve. If patients with AIS with large lumbar curves have LSTV, consideration should be given to stopping the distal fusion at L3 instead of L4.

LEVEL OF EVIDENCE