Conversion of External Fixator to Intramedullary Nail in Tibial fractures.

Abstract

Conversion of provisional external fixation to intramedullary nail (IMN) in femur fractures has been reported to be safe within 14 days of initial surgery. However, there is no current literature guiding this practice in tibial fractures. The purpose of this study was to identify the time period when conversion of external fixation to nail in tibial fractures is safe. After obtaining IRB approval, tibial fractures (OTA 41A, 42, 43A) that received provisional ex-fix and were converted to IMN from 2009 to 2019 were retrospectively reviewed. Skeletally mature patients with minimum 6 months of follow-up were included. The primary outcome was deep infection. External fixation days were categorized as less than 7, 8 to 14, and 15+ days. Risk ratios of infection were estimated using generalized linear regression with a Poisson distribution. A separate regression model evaluated risk factors for infection using both the external fixation and non-external fixation tibial cohorts. Twenty-eight patients (32%) were treated for deep infection. The infection rate for closed fractures was 28% (11 of 39 patients) and for open fractures was 35% (17 of 49 patients) ( P = 0.56). Examining both tibial cohorts, external fixation (odds ratio [OR] = 2.39, P = 0.017), open fracture (OR = 3.13, P = 0.002), and compartment syndrome (OR = 2.58, P = 0.01) were all associated with infection in regression modeling. Median external fixation days for patients with deep infection was 8 days (Inter-quartile range, 3 to 18 days) as compared with 4 days (IQR, 2 to 9 days) in patients without infection ( P = 0.06). While controlling for open fractures, the 8- to 14-day group had RR = 1.81 ( P = 0.2), and the 15+-day group had RR = 2.67 ( P = 0.003) as compared with the <7-day group. Infection rates of tibial fracture patients treated with external fixation and converted to IMN were high. Surgeons should strongly consider the necessity of external fixation for these fractures. Earlier conversion of external fixation to definitive fixation reduced infection rates. Level IV-case series.