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Study evaluates reliability of modified radiographic union score in tibia fractures with bone loss
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NEW ORLEANS — A presenter at the American Academy of Orthopaedic Surgeons Annual Meeting said the modified radiographic union score for tibia fractures had similar reliability compared to other cortical scoring systems in the assessment of progression to union in patients treated for open diaphyseal tibia shaft fractures.
“[The modified radiographic union score for tibia fractures] mRUST appears similarly reliable to prior studies in the assessment of progression to union in patients with open axial tibia fractures with bone defects if eventual fixation is with a nail or plate,” Stuart L. Mitchell, MD, said during his presentation. “However, mRUST may not be as reliable in patients with treated with definitive fixation or with previous removal of instrumentation. Bone grafting and the size of the bone defect did not impact of the interrater reliability substantially.”
Mitchell and colleagues identified 234 patients with open diaphyseal tibia shaft fractures and a bone defect of less than 1 cm. Investigators used radiographs for scoring between 11 and 13 months after the injury. On average, the time from definitive fixation to selected radiograph was 278 days. The mRUST was applied to each case by three orthopedic surgeons. The score was not calculated if the cortex could not be evaluated due to the implant. The intra-class correlation coefficient (ICC) and Krippendorff’s alpha were used to assess the interrater reliability.
In 171 patients, raters were able to score all four cortices. Two raters scored all four cortices in 28 patients, and no raters were able to score all four cortices in 12 patients. Investigators noted 160 patients were internally fixed and 74 patients were treated with a ring external fixator. There were 112 patients, who prior to scored X-rays, had bone graft on average at 187 days.
Agreement based on Krippendorff’s alpha and for the ICC was 0.67 and 0.69, respectively. Compared to patients treated with external fixation, patients treated with internal fixation had higher agreement for Krippendorff’s alpha and the ICC. The level of agreement was not affected by bone grafting, but intermediate defects had slightly better agreement compared with smaller or larger defects. – by Monica Jaramillo
Ref erence:
Tornetta P, et al. Paper #460. Presented at: American Academy of Orthopaedic Surgeons Annual Meeting; March 6-10, 2018; New Orleans.
Disclosure: Mitchell reports no relevant financial disclosures.