Defining the Lower Limit of a “Critical Bone Defect” in Open Diaphyseal Tibial Fractures

    loading  Checking for direct PDF access through Ovid



To determine healing outcomes of open diaphyseal tibial shaft fractures treated with reamed intramedullary nailing (IMN) with a bone gap of 10–50 mm on ≥50% of the cortical circumference and to better define a “critical bone defect” based on healing outcome.


Retrospective cohort study.


Forty patients, age 18–65, with open diaphyseal tibial fractures with a bone gap of 10–50 mm on ≥50% of the circumference as measured on standard anteroposterior and lateral postoperative radiographs treated with IMN.


IMN of an open diaphyseal tibial fracture with a bone gap.


Level-1 trauma center.

Main Outcome Measurements:

Healing outcomes, union or nonunion.


Forty patients were analyzed. Twenty-one (52.5%) went on to nonunion and nineteen (47.5%) achieved union. Radiographic apparent bone gap (RABG) and infection were the only 2 covariates predicting nonunion outcome (P = 0.046 for infection). The RABG was determined by measuring the bone gap on each cortex and averaging over 4 cortices. Fractures achieving union had a RABG of 12 ± 1 mm versus 20 ± 2 mm in those going on to nonunion (P < 0.01). This remained significant when patients with infection were removed. Receiver operator characteristic analysis demonstrated that RABG was predictive of outcome (area under the curve of 0.79). A RABG of 25 mm was the statistically optimal threshold for prediction of healing outcome.


Patients with open diaphyseal tibial fractures treated with IMN and a <25 mm RABG have a reasonable probability of achieving union without additional intervention, whereas those with larger gaps have a higher probability of nonunion. Research investigating interventions for RABGs should use a predictive threshold for defining a critical bone defect that is associated with greater than 50% risk of nonunion without supplementary treatment.

Level of Evidence:

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Related Topics

    loading  Loading Related Articles