Response to Letter to the Editor

To the Editor,

We would like to express our gratitude to Dr Ali for his interest in our study and for providing insightful comments. We acknowledge the concern raised regarding the clinical correlation of a 5° kyphosis progression and agree that its significance may be limited. However, we opted for a 5° threshold to represent kyphosis progression considering the potential influence of radiographic and measurement errors, which could result in differences of less than 5°. It is indeed the goal of every surgeon to prevent any kyphosis progression in their patients.

Given the retrospective nature of our study, we did not have systematic records of back pain. Furthermore, it is important to note that pain can originate from various sources beyond kyphotic deformity. Factors such as mechanical instability or pseudoarthrosis of the injured vertebra, degeneration of compensatory segments in other regions of the spine, or fatigue of the muscular apparatus as a compensatory mechanism can contribute to pain.1 To provide more comprehensive information on this aspect, a well-designed prospective study is warranted.

Regarding the diagnosis of posterior ligamentous complex (PLC) injuries, we acknowledge that there are no standard and widely used criteria. During the study period, we used an interspinous widening of more than 2 mm and other criteria mentioned in the study as routine diagnostic criteria for PLC injuries in our institution.2–5 The higher percentage of PLC injuries in our study compared with the study by Aly MM et al6 could be attributed to 2 factors: (1) our study included only operated patients who had a higher likelihood of having PLC injuries and (2) differences in the population and mechanisms of injuries compared with other studies.

In summary, Dr Ali has raised concerns about the definition of PLC injuries and the clinical correlation of kyphosis progression. However, we maintain that when considering the study in its entirety, we have demonstrated a significant association between PLC injuries and kyphosis progression.

• This manuscript is generously published free of charge by ISASS, the International Society for the Advancement of Spine Surgery. Copyright © 2023 ISASS. To see more or order reprints or permissions, see http://ijssurgery.com.