Quantitative three-dimensional computed tomography analysis of glenoid fracture patterns according to the AO/OTA classification

Hypothesis/BackgroundThis study measures the characteristics of glenoid fractures to determine if the AO Foundation and Orthopaedic Trauma Association (AO/OTA) classification captures the most common fracture patterns. The primary null hypothesis was that surface area and degree of fragmentation do not differ among the different fracture types. Secondarily, we tested if there was a relationship between high- vs. low-energy trauma and fracture classification.MethodsThree-dimensional models were created for a consecutive series of 53 fractures. The fracture classifications, the number of fragments, and the fragmented articular surface area were related to the type of injury. The difference of articular surface size and number of fragments among classification groups was analyzed with the Kruskal-Wallis test.ResultsThere is a significant difference in fractured articular surface area among classification groups. Compared with transverse and multifragmented fractures, both anterior and posterior fractures involved significantly less of the articular surface area. High-energy trauma is associated with transverse and multifragmented fractures in 93% of the cases. It is associated with a greater number of fracture fragments and fracture of a larger percentage of the glenoid surface area, with a mean fractured surface of 60% for high-energy fractures and 25% for low-energy injuries.Discussion/ConclusionQuantitative 3-dimensional CT analysis confirms that the current AO/OTA classification adequately characterizes and discriminates glenoid fracture patterns. The classification groups are related to the fragmented articular surface area and the number of fragments. Also, the mechanism of injury is related to the classification group, which supports the clinical relevance of the classification.