Fri., 10/15/10 Knee, Tibia & Pediatrics, Paper #56, 3:47 pm OTA-2010
The Critical-Sized Defect in the Tibia: Is It Critical? Results from the SPRINT Trial (FDA=Non-U.S. research conducted within guidelines of my country)
David W. Sanders, MD1, on behalf of the SPRINT (Study to Prospectively
Evaluate Reamed Intramedullary Nails in Tibial Fractures) Investigators;
1Department of Surgery, Division of Orthopaedic Surgery, University of Western Ontario,
London, Ontario, Canada
Purpose: A critical-sized defect in a long bone is defined as one that requires surgical intervention to heal. For the tibia, there is no clear definition of “critical size”. In the SPRINT trial, a critical-sized defect of the tibial diaphysis was defined as a fracture gap at least 1 cm in length and involving over 50% of the cortical diameter, based on published reports of failed exchange nailing and a consensus process. The purpose of this study is to determine if this definition of a “critical-sized defect” was accurate, to discern which other factors may predict reoperation in patients with the critical defect, and to compare the patient-based outcomes of these patients to patients without a critical defect.
Methods: Of the over 1200 patients with diaphyseal tibia fractures enrolled in the SPRINT trial, 37 patients had a “critical-sized defect”. By definition, secondary procedures to gain union were allowed in these patients, but not required. To determine if these defects are in fact critical, we evaluated these patients for planned and unplanned secondary interventions to gain union. Additionally, we evaluated which other factors predicted the need for reoperation. Finally, the 37 patients with a critical defect were compared to the larger cohort of patients without a defect with respect to demographics, mechanism of injury, fracture characteristics, and patient-based outcome.
Results: Of the 37 patients with a large fracture gap, 7 patients had a secondary procedure planned at the time of the initial surgery. Of the remaining 30 patients in whom the attending physician adopted a “watch and wait” strategy, 16 patients (53%) required secondary intervention(s) to gain union and 14 patients (47%) did not. Additional surgery to gain union was required less commonly in patients treated with a reamed nail (P = 0.04) and in female patients (P = 0.04). Smoking and AO/OTA 42-C-type fractures were more common in the patients who required a reoperation, but this was not statistically significant. As compared with the rest of the SPRINT cohort, patients with a critical-sized defect were more likely to have a high-energy mechanism of injury (P = 0.001), AO-OTA fracture type 42-B or C (P < 0.001), and location involving the middle third of the tibia (P = 0.02). Of note, the mean (SD) of the 12-month Short Form–36 Health Survey Questionnaire Physical Component Score in patients with a critical-sized defect was 38.2 (10.5), poorer than 43.3 (10.7) in the overall cohort (P = 0.02; difference = 5.2; 95% confidence interval, 0.8-9.6).
Conclusion: Tibial diaphyseal defects of ≥1 cm and >50% cortical circumference healed without additional surgery in 47% of cases. This definition of a critical-sized defect is not “critical.” However, as compared with the overall cohort of tibial fractures, patients with these bone defects had a higher rate of reoperation and worse patient-based outcomes. Further investigation is required to determine which factors predict union in this challenging fracture to avoid unnecessary secondary surgery.
Alphabetical Disclosure Listing (292K PDF)
• 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.