Letter to editor on “Association between post-trauma platelet-lymphocyte ratio and nonunion in patients with extremity fractures: a multicenter retrospective cohort study”

To the Editor, Li et al report a large five-center retrospective cohort (n = 30,791; 2020–2022) evaluating whether early post-trauma platelet–lymphocyte ratio (PLR, within 48 h) predicts postoperative nonunion after extremity fracture surgery[1]. Given the substantial disability and resource burden attributable to nonunion, scalable biomarkers that enable early risk stratification are highly desirable[2,3]. This commentary was prepared in line with the TITAN 2025 guideline to promote transparent and responsible reporting[4]. The study’s central finding is both novel and biologically plausible: lower PLR is associated with higher nonunion risk. Using restricted cubic splines, the authors demonstrate a significant negative, non-linear dose–response relationship and identify PLR 145 as an inflection point; PLR < 145 remained independently associated with nonunion after extensive adjustment (adjusted OR 1.265)[1]. This directionality challenges a simplistic “more inflammation is always worse” narrative and instead aligns with contemporary concepts that the early fracture hematoma and coordinated immune–coagulation responses are integral to successful repair[2]. Several design features strengthen credibility. The sample size and multicenter nature are exceptional, and nonunion is defined using a stringent, widely used clinical standard (≥9 months without progression for 3 months) with outcome confirmation via record review plus telephone/outpatient follow-up and adjudication for uncertain cases[1]. The authors also account for many established nonunion correlates (injury characteristics, perioperative factors, comorbidities, and laboratory variables), which is important given the multifactorial epidemiology of nonunion[1,3]. Key limitations should temper translation. PLR is a composite marker influenced by thrombocytopenia, lymphocyte dynamics, hemodilution, stress responses, and occult infection – phenotypes with different implications for bone biology and care pathways. Timing within the 48-hour window and PLR kinetics (trajectory rather than a single value) were not captured, and external generalizability beyond tertiary trauma centers warrants confirmation[1]. Finally, before PLR can be operationalized, its incremental predictive value over established clinical risk factors should be quantified in prospective studies[2,3]. Overall, Li et al position early PLR as a promising, low-cost signal for nonunion risk stratification at scale[1]. The next step is prospective validation with standardized sampling timepoints and serial monitoring, coupled with evaluation of whether PLR-guided pathways (e.g., intensified follow-up, optimization of modifiable risks, and fixation strategy review) improve patient-important outcomes without over-treatment.