Tibial shaft fractures are among the most consequential lower-extremity injuries managed in orthopaedic trauma, with particularly high infectious risk in severe open patterns and persistent challenges in risk stratification despite contemporary fixation and limb-salvage pathways [1,2]. These injuries occur across a broad age spectrum, typically following high-energy mechanisms in younger patients and lower-energy falls in older individuals with compromised bone and physiologic reserve [3]. The associated clinical burden is substantial, driven by postoperative medical complications, fracture-related infection, delayed union/nonunion, and downstream reoperations that can prolong recovery and increase resource utilization [[1], [2], [3]].

Increasing attention has therefore focused on modifiable, patient-level factors that influence outcomes after fracture fixation. Among these, nutritional status is an underrecognized but clinically meaningful determinant of recovery [4,5]. Malnutrition is commonly assessed using readily available laboratory markers (eg, albumin and leukocyte/lymphocyte parameters) and has long been linked to impaired physiologic reserve, delayed tissue repair, and vulnerability to infection [1,6,7]. Across multiple orthopaedic populations, especially elective arthroplasty, poor nutritional status has been associated with higher rates of wound complications, surgical site infection, medical morbidity, unplanned intensive care unit (ICU) admission, and increased cost of care [[8], [9], [10], [11], [12], [13], [14], [15], [16], [17]]. Similar associations have also been demonstrated in trauma cohorts, where poor nutritional status portends worse perioperative outcomes in older, medically complex patients [18]. Importantly, our group recently demonstrated that laboratory-defined malnutrition was associated with increased infectious, vascular, and wound complications following distal femur fracture fixation, underscoring the relevance of nutritional vulnerability in urgent fracture pathways [19].

Within tibial fracture care specifically, prior studies support a clinically relevant relationship between hypoalbuminemia and adverse healing or infectious outcomes. In a prospective cohort of adult diaphyseal tibial fractures, Ali et al. found that lower serum albumin correlated with worse radiographic healing progression and healing outcomes [9]. In higher-energy tibial injuries, Groznik et al. reported that decreased postoperative albumin, alongside elevated inflammatory markers, was associated with acute posttraumatic osteomyelitis [20]. Additional evidence links hypoalbuminemia (often in combination with anemia) to surgical site infection in open tibial fractures, and to infection risk after operative fixation of closed tibial plateau fractures [21,22]. Despite these signals, large-scale outcome data evaluating laboratory-defined malnutrition in adult tibial shaft fracture fixation, particularly with longer-term endpoints such as nonunion, osteomyelitis, hardware removal, and amputation, remain limited.

The primary aim of this study was to evaluate the association between preoperative laboratory-defined malnutrition and 90-day postoperative medical and surgical complications in adults undergoing operative fixation of tibial shaft fractures. A secondary aim was to determine whether preoperative malnutrition was associated with increased 2-year fracture healing complications and limb-related outcomes following tibial shaft fracture fixation. We hypothesized that malnutrition would be independently associated with increased early morbidity and higher rates of nonunion and downstream limb complications at two years.