Smoking, Obesity, and Disability Benefits or Litigation Are Not Associated with Clinically Important Reductions in Physical Functioning After Intramedullary Nailing of Tibial Shaft Fractures: A Retrospective Cohort Study
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BACKGROUND: Forty percent of long bone fractures involve the tibia. These fractures are associated with prolonged recovery and may adversely affect patients' long-term physical functioning; however, there is limited evidence to inform what factors influence functional recovery in this patient population. QUESTION/PURPOSE: In a secondary analysis of a previous randomized trial, we asked: What fracture-related, demographic, social, or rehabilitative factors were associated with physical function 1 year after reamed intramedullary nailing of open or closed tibial shaft fractures? METHODS: This is a secondary (retrospective) analysis of a prior randomized trial (Trial to Re-evaluate Ultrasound in the Treatment of Tibial Fractures; TRUST trial). In the TRUST trial, 501 patients with unilateral open or closed tibial shaft fractures were randomized to self-administer daily low-intensity pulsed ultrasound or use a sham device, of which 15% (73 of 501) were not followed for 1 year due to early study termination as a result of futility (no difference between active and sham interventions). Of the remaining patients, 70% (299 of 428) provided full data. All fractures were fixed using reamed (298 of 299) or unreamed (1 of 299) intramedullary nailing. Thus, we excluded the sole fracture fixed using unreamed intramedullary nailing. The co-primary study outcomes of the TRUST trial were time to radiographic healing and SF-36 physical component summary (SF-36 PCS) scores at 1-year. SF-36 PCS scores range from 0 to 100, with higher scores being better, and the minimum clinically important difference (MCID) is 5 points. In this secondary analysis, based on clinical and biological rationale, we selected factors that may be associated with physical functioning as measured by SF-36 PCS scores. All selected factors were inserted simultaneously into a multivariate linear regression analysis. RESULTS: After adjusting for potentially confounding factors, such as age, gender, and injury severity, we found that no factor showed an association that exceeded the MCID for physical functioning 1 year after intramedullary nailing for tibial shaft fractures. The independent variables associated with lower physical functioning were current smoking status (mean difference -3.0 [95% confidence interval -5 to -0.5]; p = 0.02), BMI > 30 kg/m2 (mean difference -3.0 [95% CI -5.0 to -0.3]; p = 0.03), and receipt of disability benefits or involvement in litigation, or plans to be (mean difference -3.0 [95% CI -5.0 to -1]; p = 0.007). Patients who were employed (mean difference 4.6 [95% CI 2.0 to 7]; p < 0.001) and those who were advised by their surgeon to partially or fully bear weight postoperatively (mean difference 2.0 [95% CI 0.1 to 4.0]; p = 0.04) were associated with higher physical functioning. Age, gender, fracture severity, and receipt of early physical therapy were not associated with physical functioning at 1-year following surgical fixation. CONCLUSION: Among patients with tibial fractures, none of the factors we analyzed, including smoking status, receipt of disability benefits or involvement in litigation, or BMI, showed an association with physical functioning that exceeded the MCID. LEVEL OF EVIDENCE: Level III, therapeutic study.
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