Risk factors for delayed healing after traumatic limb fractures and a comparative assessment of external versus...

To identify risk factors for delayed healing after traumatic limb fractures and to compare outcomes between internal and external fixation among patients with delayed union.

We retrospectively reviewed 490 consecutive patients treated between January 2021 and June 2024. Patients were classified into normal healing (n=356) and delayed healing (n=134) groups. Candidate predictors were screened with Least Absolute Shrinkage and Selection Operator (LASSO) regression, followed by univariate and multivariable logistic regression. Receiver operating characteristic (ROC) analysis was used to derive optimal cut-offs.

Compared with the normal-healing group, patients with delayed healing were older and had higher BMI, and were more likely to have a history of smoking, diabetes, osteoporosis, or malnutrition; they also differed in fracture types, comminution, operative time, and blood loss (most comparisons P≤0.013). LASSO selected ten variables, including age, BMI, and smoking. ROC-derived thresholds were 62.5 years for age, 24.5 for body mass index (BMI), and 37.5 minutes for operative time. In multivariable analysis, age ≥62.5 years (odds ratio [OR] =2.233; P=0.001), BMI ≥24.5 (OR=5.194; P<0.001), smoking, diabetes, osteoporosis, malnutrition, and greater comminution remained independently associated with delayed healing. Among patients with delayed union, BMI differed by initial fixation method (P=0.027), with a higher BMI in those initially treated with internal fixation (median 24.00 vs. 23.00).

Delayed healing after traumatic limb fractures is multifactorial. Older age, higher BMI, smoking, diabetes, osteoporosis, malnutrition, and fracture comminution show independent associations with risk. LASSO aided parsimonious variable selection and may help flag high-risk patients. The influence of initial fixation strategy on subsequent delayed healing requires further study.