The Development of a Universally Accepted Sacral Fracture Classification: A Survey of AOSpine and AOTrauma Members
Authors: Schroeder Gregory D. , Vaccaro Alexander R. , Kurd Mark F. , Kepler Christopher K. , Krieg James C. , Kleweno Conor P. , Firoozabadi Reza , Kandziora Frank , Schnake Klaus J. , Rajasekaran S. , Holstein Jorg H. , Sagi Henry C. , Dvorak Marcel F. , Vialle Luiz R. , Oner F. C. , Bellabarba Carlo , Chapman Jens R. 
Published: April 2016

Introduction Sacral fractures are complex injuries that pose diagnostic and technical challenges for surgeons. While multiple classifications have been proposed, there is not a comprehensive, universally accepted classification. The AOSpine Trauma Knowledge Forum partnered with orthopaedic traumatologists from AOTrauma to develop a straightforward, hierarchical classification system for sacral fractures. While the classification was developed via a consensus process of clinical experts, the authors solicited input from the global community to ensure that the proposed classification could achieve global acceptance. Material and Methods Prior to finalizing the new AOSpine Sacral Injury Classification System, a survey was sent to all members of AOSpine and AOTrauma. The survey included the preliminary sacral classification as well as questions asking for their input on key parts of the classification. Along with demographic information, the following four questions were asked: (1) Since type B injuries in the new AOSpine sacral classification refer only to vertical fracture patterns and exclude injuries with a transverse component, do you agree that there is an increase in the risk of neurologic injury as the B subtype increase: B1—an injury medial to the foramen; B2—an injury lateral to the foramen and B3 an injury through the foramen. (2) Do you think the hierarchical nature of the sacral classification is appropriate with: A = transverse; B = Unilateral vertical fracture; C = Any fracture that leads to spinopelvic instability. (3) Do you think the integrity of the L5/S1 facet is adequately considered in this classification system? (4) Do you think C0 (a non-displaced sacral U fracture that may be seen in low energy insufficiency fractures) is a clinically relevant entity that deserves its own spot in the classification? Results A total of 596 surgeons from all six AO regions of the world responded to the survey. 70.9% of respondents were orthopaedic trauma surgeons, 18.5% were orthopaedic spine surgeons and 4.7% were neurosurgeons. Overall 78.1% of respondents agreed that the B subtypes were correctly ordered for an increase in the risk of a neurologic injury. 86.1% of respondents felt that the hierarchical nature of the classification was appropriate. 82.9% of respondents felt that the L5/S1 facet was adequately considered in the classification, and 84.1% of surgeons felt that C0 is clinically relevant entity that deserves its own spot in the classification. When surgeons were stratified as either a trauma surgeon or a spine surgeon (orthopaedic or neurosurgeon), significantly more spine surgeons than trauma surgeons agreed with the organization of B type injuries (84.7% versus 75.4%, respectively, p = 0.03); however, still more than 3 in 4 trauma surgeons agreed with the organization of B type injuries. No other significant difference was identified by specialty. Additionally, no significant difference (p > 0.39) was found when respondents were grouped by years in practice (0–10 years, 11–20 years and >20 years). Conclusion While validation studies are ongoing for the new AOSpine sacral fracture classification, the classification is designed such that worldwide acceptance from both spine surgeons and trauma surgeons may be possible.