Obesity negatively affects functional recovery in OTA 42A-C tibial fractures treated with intramedullary nails.

BACKGROUND

To compare functional outcomes between obese and non-obese patients after intramedullary nail (IMN) fixation of OTA 42A-C tibial fractures. Secondarily, to compare clinical outcomes and union rates between cohorts.

METHODS

A retrospective review of tibial shaft fractures from 2012 to 2024 was conducted at a single multi-site academic institution. Inclusion criteria included: age ≥18yo, OTA 42A-C fracture, IMN fixation, and a minimum of 6 months follow-up. Demographics, injury and surgical characteristics, hospital quality measures, complications, reoperations, and functional outcomes were recorded. Functional outcomes were recorded using the Functional Ambulatory Category (FAC) score. Healing was determined using the Radiographic Union for Tibia (RUST) score. Patients were divided into two groups based on their BMI at the time of injury: non-obese (BMI <30 kg/m2) and obese (BMI ≥30 kg/m2). Univariate comparisons between cohorts were performed, and multivariable regression was used to adjust for confounders.

RESULTS

286 patients met inclusion criteria: 60 (21.0%) were obese and 226 (79.0%) were non-obese. The mean follow-up time was 13.60 ± 7.90 months. There were no differences in injury or demographic characteristics, besides a higher rate of diabetes in the obese group (20% vs. 5.3%, p < 0.001). Obesity was associated with lower 3-month (B = -0.352, p = 0.009), 6-month (B = -0.283 p = 0.013) and 12-month (B = -0.181 p = 0.039) FAC scores when controlling for baseline FAC score, age, fracture pattern, diabetes, and open fractures. The obese group was not associated with fracture nonunion (81.7% vs. 90.3%, p = 0.064) and showed no difference in healed-by times (6.28 ± 2.45 [months] vs. 6.13 ± 2.83, p = 0.751). The obese group had a higher rate of amputation (5% vs. 0%, p < 0.001) but no difference in overall complication rate (28.3% vs. 18.0%, p = 0.081).

CONCLUSIONS

Obese patients who undergo intramedullary nail fixation of OTA 42A-C tibial diaphyseal fractures have worse functional ambulatory outcomes compared to their non-obese counterparts.