Is the Lumbar Modifier Useful in Surgical Decision Making?

Abstract

Two Lenke 1A curve patterns can be described based on the direction of the L4 tilt. This distinction has ramifications regarding selection of fusion levels and assessing surgical outcomes. The A and B lumbar modifiers do not describe 2 distinct curve types within the Lenke 1 group; however, the tilt direction of L4 does allow subdivision of the Lenke 1A curves into 2 distinguishable patterns (1A-R and 1A-L). The 1A-L curves are similar to 1B curves and different in form and treatment from the 1A-R pattern.

Distal fusion level selection in Lenke 1A curves according to axial plane analyses

“…Skeletal immaturity and selection of LIV were found to be highly correlated with adding-on [4,22]. Distal adding-on has been found to be more common in Lenke 1A right curves subclassified by Miyanji et al [18,23]. To prevent adding-on in Lenke 1A right curves, Cho recommended selecting an LIV one level distal to NVs or one or two levels proximal to SV.…”

“…Digital assessment may be of potential benefit with regard to more precise vertebral rotation measurement, as suggested by Potter et al [17]. Miyanji et al [18] subdivided Lenke 1A curves according to the direction of L4 vertebra tilt (1A-L to the left and 1A-R to the right). He suggested that the 1A-L curve type could be fused to the SV, whereas the 1A-R curve type (similar to the King IV curve) generally requires two additional levels compared with the 1A-L curve.…”

Radiographic Features of the Lenke 1A Curves to Help to Determine the Optimum Distal Fusion Level Selection

“…There was a high risk of postoperative adding on when the distal fusion level was performed two or more proximal to distal NV. Recently Miyanji et al 4 The limitations of this study were it being a retrospective review and that a meaningful statistical analysis was not feasible in some subgroups because of a small number of patients.…”

Adolescent idiopathic scoliosis: current perspectives

“…Despite its goal of being comprehensive, authors have reported on some of the limitations of the Lenke system. 56 The lumbar modifier has been challenged by Miyanji et al,56 noting that the A and B modifiers in Lenke 1 curves did not describe two distinct curve types within the Lenke 1 group, but rather the tilt direction of the L4 vertebrae was more useful in distinguishing two truly different curve patterns within the Lenke 1A classification (Figure 2). Also, the classification system does not include any clinical information, such as shoulder-height differences, trunk balance, or degree of skeletal immaturity.…”