Fri., 10/14/11 Tibia, Paper #55, 11:55 am OTA-2011
Tibia Nonunion Prediction: Is It Possible?
Justin S. Yang, MD; Jesse Otero, MD; Christopher M. McAndrew, MD;
William M. Ricci, MD; Michael J. Gardner, MD;
Orthopaedic Trauma Service, Washington University School of Medicine,
St. Louis, Missouri, USA
Purpose: Treatment of tibial delayed unions and nonunions following intramedullary fixation has been a controversial topic among orthopaedic surgeons. The timing and indication of secondary surgical intervention have not been clearly defined. A recent multicenter prospective study (SPRINT [Study to Prospectively Evaluate Reamed Intramedullary Nails in Patients in Tibial Fractures) concluded that delaying surgical interventions for at least 6 months may decrease the need for reoperation. However, at 3 months postoperatively, if the surgeon is able to accurately predict that the patient will progress to nonunion at 6x months, prompt treatment can proceed, minimizing patient morbidity, discomfort, and debilitation. The purpose of this study was to determine if it was possible to reliably predict at 3 months after index intramedullary nailing if a patient would proceed to nonunion.
Methods: 56 patients who underwent intramedullary fixation for tibia fractures between 2005 and 2009 and had incomplete healing at 3 months were identified. A clinical vignette was created for each patient that included the 3-month radiographs, age, gender, weight, mechanism of injury, Gustilo type if open fracture, medical and smoking history, and if any biologics were used. The vignettes and a questionnaire were distributed to 3 fellowship- trained trauma surgeons, who were asked to predict if each fracture would go on to nonunion, and if so the reasons. 29 patients subsequently developed a nonunion at 6 months postoperatively, based on radiographic and clinical criteria, and all underwent nonunion repair. 27 patients achieved full union by 6 months without additional surgery, defined as painless ambulation and radiographic bridging of all 4 cortices. A comparison of the surgeon predictions and actual clinical outcomes were used for statistical analysis, which included calculation of the diagnostic accuracy, sensitivity and specificity, and positive and negative predictive values.
Results: The combined overall diagnostic accuracy of all 3 surgeons was 74% (73%, 73%, and 75%). Sensitivity and specificity were 62% and 77%, respectively. Positive and negative predictive values were 73% and 69%, respectively. In patients who were correctly predicted to proceed to nonunion, radiographic features, such as lack of callus formation, and mechanism of injury were the most common reasons cited. In 10 patients where all 3 surgeons correctly predicted nonunion, 4 of the 10 patients had diabetes, 8 patients had high-energy open fractures, 8 patients smoked, and none had callus formation. In 4 patients where all 3 surgeons failed to correctly predict nonunion, none had diabetes, 3 of the 4 patients had open fractures, 3 patients smoked, and none had callus formation. In 9 patients with diabetes, the diagnostic accuracy was 88%. Of the 30 patients who smoked, the diagnostic accuracy was 76%. Of the 31 patients with signs of radiographic healing, the diagnostic accuracy was 74%. Of the 34 patients with open fractures, the diagnostic accuracy was 67%.
Conclusion: Clinical judgment at 3 months allows for correct prediction of eventual nonunion development in a substantial percentage of patients. Lack of callus formation and mechanism of injury were the most common reason for a surgeon to predict nonunion. Predicting nonunion in diabetic patients had a higher success rate than other patient factors. We suggest that analysis of the entire clinical picture be used for patient management. A protocol of waiting for 6 months before reoperation in all patients may unnecessarily subject patients to prolonged disability and discomfort. Nonunion prediction may be even higher in clinical practice, when additional subtleties are available, such as serial radiographs and a pain with weight bearing.
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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.