Risk Factors for Failure of Repair of Diaphyseal Tibial Nonunions: A Retrospective Cohort Study of 108 Patients

OBJECTIVES: To determine rates and risk factors for additional nonunion surgery and final radiographic healing following diaphyseal tibial nonunion repair. METHODS: All consecutive patients aged ≥18 years who underwent diaphyseal (AO/OTA 42) tibial nonunion repair with (exchange) intramedullary nailing (IMN) or open reduction and internal fixation (ORIF) between 2001 and 2024 with ≥6 months follow-up were included. The primary outcome was the rate of additional nonunion surgery. The secondary outcome was radiographic healing (defined as Modified Radiographic Union Score for Tibia mRUST ≥11) at final follow-up. Multivariable logistic regression was used to determine the association of patient, nonunion, and treatment characteristics with additional nonunion surgery. RESULTS: A total of 108 patients were included (70% male, median age 42 years IQR 28-53). Sixty patients (56%) were treated with IMN, of whom 54 (50%) underwent exchange IMN, and 48 (44%) were treated with ORIF. Autograft was used in 39 patients (36%) and bone graft substitutes in 21 (19%). Twenty-seven patients (25%) required additional nonunion surgery, of whom 5 (4.6%) ultimately underwent amputation. In multivariable analysis, current smoking (OR: 4.28, p = 0.015), initial open fracture (OR: 3.94, p = 0.045), and presence of a bone defect (OR: 9.20, p < 0.001) were associated with increased odds of additional nonunion surgery, while decortication was associated with reduced odds (OR: 0.30, p = 0.038). The final radiographic healing rate was 90%. CONCLUSIONS: 1 in 4 patients required additional surgery for persistent nonunion and 1 in 25 ultimately underwent amputation. The findings highlight the importance of smoking cessation prior to nonunion repair and the potential benefit of decortication, although this latter finding should be interpreted within the context of the overall treatment strategy. Furthermore, the presence of a bone defect and an initial open injury were associated with higher odds of additional nonunion surgery. Overall, 9 in 10 patients achieved radiographic healing.