Commentary on “Scoliosis Progression After Transforaminal Full-Endoscopic Lumbar Foraminotomy: A Case Presentation and Literature Review”
Article information
To the editor,
We read with great interest the article by Soeda et al. [1], “Scoliosis Progression After Transforaminal Full-Endoscopic Lumbar Foraminotomy: A Case Presentation and Literature Review.” The authors describe the novel radiographic finding of “lateral kissing spine” and suggest its potential role in limiting postoperative scoliosis progression. While this is an intriguing concept, we would like to respectfully raise 2 points that may add perspective.
1. Relationship to Lumbosacral Transitional Vertebrae
The described contact between the L5 transverse process and the sacral ala closely resembles the well-established entity of lumbosacral transitional vertebrae (LSTV), commonly known as Bertolotti syndrome. Castellvi et al. [2] proposed a widely cited radiographic classification that distinguishes enlarged transverse processes, pseudarthrosis, and fusion (types I–IV). LSTV is estimated to occur in approximately 10%–15% of the general population and has been linked to accelerated disc degeneration and altered spinopelvic parameters [3,4]. Within this context, the “lateral kissing spine” may represent a subset of Castellvi type II–III variants rather than a novel anatomical finding. Explicitly classifying such cases within the Castellvi system would improve clarity, enable direct comparison with existing literature, and support more meaningful integration into established biomechanical and clinical frameworks.
2. Radiographic Progression and Measurement Error
The authors report a mean Cobb angle progression of +0.29° in patients with lateral contact compared with +2.1° in those without contact, a difference that reached statistical significance [1]. However, these values fall well within the known intra- and interobserver variability of Cobb angle measurements, typically 3°–5° on plain radiographs [5]. In addition, most scoliosis studies regard an increase of ≥5° as the threshold for clinically meaningful progression. Without reporting measurement reliability (such as intra- or interobserver intraclass correlation coefficients), the observed differences may reflect measurement error rather than a true biological effect. To strengthen the validity of these findings, future research should provide reproducibility metrics and adopt ≥5° progression as the clinical benchmark.
3. Clinical Implications and Follow-up Duration
The suggestion that the presence of lateral contact may justify decompression without fusion is thought-provoking but remains premature. Adult degenerative scoliosis frequently progresses over several years, and the current mean follow-up of approximately 12 months is not sufficient to establish long-term stability [1]. Well-documented predictors of curve progression include apical vertebral translation, sagittal imbalance, osteoporosis, and spondylolisthesis [6,7]. Without considering these factors, the apparent protective effect of transverse process contact may be confounded. Prospective studies with extended follow-up and adjustment for known progression predictors are needed before this anatomical feature can be incorporated into clinical decision-making regarding decompression versus fusion.
In conclusion, Soeda et al. [1] have highlighted an under-recognized radiographic configuration that may have clinical relevance. Nevertheless, situating “lateral kissing spine” within the established LSTV framework, addressing limitations of Cobb angle measurement, and extending follow-up duration are essential steps before this feature can be adopted as a reliable marker in surgical planning.
Notes
Conflicts of Interest
The authors have nothing to disclose.