Association between time to weight bearing and rates of nonunion, delayed union, and malunion after intramedullary nailing of tibial shaft fractures.

Abstract

Intermedullary nailing (IMN) is the gold standard for tibial shaft fractures in adults with the goal of allowing early weight bearing. The purpose of this study was to determine the association between time to weight bearing as tolerated (WBAT) after tibial shaft IMN fixation and fracture nonunion, delayed union, and tibial deformity at final follow-up. A retrospective cohort of patients who sustained extra-articular tibial shaft fractures treated with IMN at two level 1 trauma centers were collected from 2010 to 2021. A minimum follow-up of six months was required unless there was presence of clinical and radiographic union prior to six months. Time to allowance of WBAT was the primary independent variable and primary outcomes included nonunion, delayed union greater than 6 months, and tibial deformity were assessed. 433 tibia fractures met inclusion criteria. Mean age was 44 years. 260 (60 %) patients were male. 194 (45 %) patients were current tobacco users. 255 (59 %) patients sustained a high energy fracture mechanism. 60 (14 %) fractures were classified as AO/OTA 42-C and 181 (42 %) fractures were open. Nonunion rate was 14 % (61/433). Mean time to WBAT was 8.3 weeks in the union group and 13.7 weeks in the nonunion group (p < 0.001). Binary logistic regression demonstrated time to WBAT as an independent predictor of nonunion (OR = 1.07 per week delay, 95 % CI 1.03-1.12, p < 0.001). Time to WBAT was also associated with delayed union (10.0 weeks delayed union versus 7.8 weeks early union, p < 0.001). There was no association between time to WBAT and tibial deformity (8.8 weeks deformity versus 9.0 weeks no deformity, p = 0.9). Earlier time to initiation of WBAT is associated with decreased nonunion and decreased delayed union after IMN of tibial shaft fractures without increased risk of malunion. Providers may consider allowing for earlier weight bearing to accelerate fracture healing with low risk of loss of fracture alignment. Level III Prognostic.