Sat., 10/6/12 Tibial Fractures, PAPER #117, 4:26 pm OTA-2012
Validation of the OTA Open Fracture Classification With Data From a Prospective Cohort Study of Limb-Threatening Tibia Fractures
Clifford B. Jones, MD1; Renan C. Castillo, PhD2; Anthony R. Carlini, MS2;
Debra L. Sietsema, PhD, RN1; MAJ Kenneth J. Nelson, MD3; LTC Anthony E. Johnson, MD3; Michael J. Bosse, MD4; Ellen J. MacKenzie, PhD2; for the LEAP (Lower Extremity Assessment Project) Study Group;
1Orthopaedic Associates of Michigan, Michigan State University, Grand Rapids, Michigan, USA;
2Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA;
3Brooke Army Medical Center, San Antonio, Texas, USA;
4Carolinas Medical Center, Charlotte, North Carolina, USA
Purpose/Hypothesis: The OTA Open Fracture Study Group recently developed a new open fracture classification system to facilitate consistent application and communication in assessment, treatment, and research. The new OTA Open Fracture Classification (OFC) includes five assessment categories: skin, muscle, arterial, contamination, and bone loss, and each category is subdivided into three descriptors of increasing severity. However, the classification has not been fully validated. The goal of this study was to use data from a prospective cohort study of severe limb-threatening tibia injuries to assess the validity of the OFC.
Methods: 347 open tibia fractures (including severe IIIA and all IIIB and IIIC) were retrospectively classified with respect to the OFC by the investigators, based on the available cohort study data. The main outcome measure was amputation. Among limb salvage patients, the main outcome measure was the Sickness Impact Profile (SIP), a gold standard measure of functional outcome, measured at 2 years postinjury. Changes in the SIP of 3 points or more have been shown to represent clinically important differences. Bivariate and multiple variable regression analysis techniques were used to study the relationship between the OFC and these outcomes.
Results: Correlations between the five OFC components were only moderate to low, ranging between 0.05 and 0.53. An increased severity of each OFC component score was significantly associated with amputations: skin, muscle, and arterial χ2 P <0.0001 for all three; contamination χ2 P = 0.0002; and bone loss χ2 P = 0.0052. The predictive power of each OFC component with respect to amputation, as measured by predictive area under the curve (AUC), was comparable to that of the Gustilo-Anderson classification. AUCs for the five OFC components ranged between 0.55 and 0.76, compared to 0.42 to 0.71 for the Gustilo classification. Among salvage patients, having the highest level of the muscle, bone loss, and arterial OFC component was associated with a 2.9, 3.8, and 5.8-point increase in disability at 2 years. A combination criterion of the highest levels of the arterial and bone loss components was developed, which occurred in 23% of this severely injured population. These criteria predicted a 4.5-point increase in disability (95% confidence interval: 0.2, 8.7; P = 0.04).
Conclusion: There is a need to improve and refine the methodology of open fracture classification to guide injury description and stratification. The new OTA OFC provides a system to classify soft-tissue injuries along five clinically significant components. The data show that these components are not correlated at such a high level as to be considered redundant and are all strongly predictive of amputation—a major clinical outcome. Furthermore, the data suggest several OFC components may be associated with clinically and statistically significant differences in long-term functional outcome.
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• The FDA has not cleared this drug and/or medical device for the use described in this presentation (i.e., the drug or medical device is being discussed for an “off label” use). ◆FDA information not available at time of printing. Δ OTA Grant.