Inter- and intra-observer agreement using the new AOSpine sacral fracture classification, with a comparison between spine and pelvic trauma surgeons.

Background: Sacral fractures treatment frequently involves both spine and pelvic trauma surgeons; therefore, a consistent communication among surgical specialists is required. We independently assessed the new AOSpine sacral fracture classification's agreement from the perspective of spine and pelvic trauma surgeons.
Methods: Complete computerized tomography (CT) scans of 80 patients with sacral fractures were selected and classified using the new AOSpine sacral classification system by six spine surgeons and three pelvic trauma surgeons. After four weeks, the 80 cases were presented and reassessed by the same raters in a new random sequence. The Kappa coefficient (κ) was used to measure the inter-and intra-observer agreement.
Results: The inter-observer agreement considering the fracture severity types (A, B, or C) was substantial for spine surgeons (κ= 0.68 [0.63 - 0.72]) and pelvic trauma surgeons (κ= 0.74 (0.64 - 0.84). Regarding the subtypes, both groups achieved moderate agreement with κ= 0.52 (0.49 - 0.54) for spine surgeons and κ= 0.51 (0.45 - 0.57) for pelvic trauma surgeons. The intra-observer agreement considering the fracture types was substantial for spine surgeons (κ= 0.74 [0.63 - 0.75]) and almost perfect for pelvic trauma surgeons (κ= 0.84 [0.74 - 0.93]). Concerning the subtypes, both groups achieved substantial agreement with, κ= 0.61 (0.56 - 0.67) for spine surgeons and κ= 0.68 (0.62 - 0.74) for pelvic trauma surgeons.
Conclusion: This classification allows an adequate communication for spine surgeons and pelvic trauma surgeons at the fracture severity type, but the agreement is only moderate at the subtype level. Future prospective studies are required to evaluate whether this classification allows for treatment recommendations and establishing prognosis in patients with sacral fractures.
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