Inter-Rater Reliability of the Modified Radiographic Union Score for Diaphyseal Tibial Fractures With Bone Defects.

Abstract

To evaluate inter-rater reliability of the modified Radiographic Union Score for Tibial (mRUST) fractures among patients with open, diaphyseal tibia fractures with a bone defect treated with intramedullary nails (IMNs), plates, or definitive external fixation (ex-fix). Retrospective cohort study. Fifteen-level one civilian trauma centers; 2 military treatment facilities. Patients ≥18 years old with open, diaphyseal tibia fractures with a bone defect ≥1 cm surgically treated between 2007 and 2012. Three of 6 orthopedic traumatologists reviewed and applied mRUST scoring criteria to radiographs from the last clinical visit within 13 months of injury. Inter-rater reliability was assessed using Krippendorff's alpha (KA) statistic; intraclass correlation coefficient (ICC) is presented for comparison with previous publications. Two hundred thirteen patients met inclusion criteria including 115 IMNs, 24 plates, 29 ex-fixes, and 45 cases that no longer had instrumentation at evaluation. All reviewers agreed on the pattern of scoreable cortices for 90.4% of IMNs, 88.9% of those without instrumentation, 44.8% of rings, and 20.8% of plates. Thirty-one (15%) cases, primarily plates and ex-fixes, did not contribute to KA and ICC estimates because <2 raters scored all cortices. The overall KA for the 85% that could be analyzed was 0.64 (ICC 0.71). For IMNs, plates, ex-fixes, and no instrumentation, KA (ICC) was 0.65 (0.75), 0.88 (0.90), 0.47 (0.62), and 0.48 (0.57), respectively. In tibia fractures with bone defects, the mRUST seems similarly reliable to previous work in patients treated with IMN but is less reliable in those with plates or ex-fixes, or after removal of instrumentation.