Dear Editor,

I came across and read with great interest the recent article by Caffard et al. [1], “Association between posterior tibial slope and anatomic spinopelvic parameters: a retrospective cross-sectional study.” The authors aimed to investigate the association between fixed anatomic spinopelvic parameters and posterior tibial slope. The findings of this study are important as they show the anatomical association between spinopelvic parameters and alignment of below-hip structures. I appreciate the authors’ contribution on this topic, however, I would like to address some points that needs further clarification.

  1. 1.

    The investigators reviewed the patients presenting with lumbar, thoracic, or cervical complaints together with knee pain but did not analyze the degree of lumbar lordosis (LL) and thoracic kyphosis, which may be associated with spinopelvic parameters. In this regard, Obeid et al. showed that LL correlated with sacral slope and with knee flexion angle [2]. Any change in the LL may cause spinopelvic alignment changes.

  2. 2.

    In this study, spinopelvic parameters were measured on a full-spine lateral radiograph. Did the patients have pelvic CT images? It might be better if the sacral measurements were made on pelvic CT images. For example, Woon et al. [3] evaluated sacrococcygeal measurements with sagittal and coronal pelvic CT scans.

  3. 3.

    Additionally, it would be better if the authors could use the more sensitive and accurate measurement methods, such as rasterstereographic analysis of the spine, which could affect the results. Michalik et al. [4] assessed the spinal posture and pelvic position using the “Formetric 4D Motion®” system and emphasized that a 3-dimensional analysis of the spinal posture and pelvic position with 4D technology is a valuable tool in the understanding and treatment of spinopelvic pathologies.