Background: When a patient is seen with a possible tibial nonunion
and equivocal findings on plain radiographs, the surgeon may choose to obtain
a computed tomography scan to better delineate the bone anatomy. However, the
sensitivity and specificity of computed tomography in this setting is not
known. We investigated the accuracy of computed tomography for detecting
nonunion in this clinical situation.
Methods: Thirty-five patients with equivocal findings on plain
radiographs underwent computed tomography scanning. The patients were first
seen at an average of 9.7 months after the injury and had undergone a mean of
2.6 prior operations. A so-called gold standard of union or nonunion was
determined by either surgical findings (for twenty-five patients who were
operatively treated) or six months of clinical observation (for ten patients
who had nonoperative treatment). Computed tomography scans were assessed by
two radiologists and one orthopaedic surgeon who were blinded to the clinical
Results: Computed tomography scans displayed very good diagnostic
accuracy. Intraobserver agreement was high (intraclass correlation coefficient
= 0.89), the sensitivity for detecting nonunion was 100%, and the overall
accuracy was 89.9%. Computed tomography was limited by a low specificity of
62%, as three patients who were diagnosed as having tibial nonunion with
computed tomography underwent surgery and were found to have a healed
Conclusions: Computed tomography displays very good accuracy in the
evaluation of tibial fracture-healing. However, it is limited by low
specificity and may sometimes misrepresent a healed fracture as a nonunion.
Surgeons must be aware of this pitfall in order to accurately determine which
patients need surgical intervention.
Level of Evidence: Diagnostic Level I. See Instructions
to Authors for a complete description of levels of evidence.