Proximal Humerus Fractures: Reliability of Neer Versus AO Classification on Plain Radiographs and Computed Tomography

Several classifications for proximal humeral fractures exist, with excellent reliability and reproducibility of such classifications being a desirable feature. Despite their widespread use, these systems are variable in both reliability and accuracy. We aimed to, a) assess and compare the reliability of the Neer (complete and abbreviated versions) and Arbeitsgemeinschaft für Osteosynthesefragenbeing (AO) classifications, and b) identify if computed tomography (CT) made any difference to the reliability of Neer and AO classifications when compared to plain radiographs alone.  Materials and methods: This is a single-centre retrospective study identifying all proximal humeral fractures presenting between February 2016 and February 2017 as a result of trauma that subsequently proceeded to CT. Two specialty orthopaedic trainees analysed the plain radiographs as well as CT images over two rounds, spaced two weeks apart. The Neer 16-grade, abbreviated Neer 6-grade and AO classifications were used. Intra- and inter-observer reliability of each classification system was assessed using the Kappa coefficient.  Results: Twenty-two patients were included. The mean age was 62 years (SD 14.5). Management changed in 9/22 patients based on CT. Computed tomography changed Neer-16 type in 16% observations, Neer-6 in 10%, and AO in 23%. This was significant when comparing Neer-6 and AO classifications (p = 0.04). Neer-6 had the best inter-observer reliability (0.737) with the management of one patient changing after CT. On X-ray and CT, intra-observer agreement was substantial, >0.7, using Neer-16 and Neer-6 (p<0.005). Inter-observer agreement for Neer-16 and Neer-6 was substantial, >0.7 (p<0.005). In comparison, intra- and inter-observer agreements for AO were lower on X-ray and CT, 0.4-0.6, (p<0.005).

Our study shows that simplicity is key with a high degree of reliability in the abbreviated Neer classification. Computed tomography allowed greater reliability than radiographs in classifying fractures, affecting management decisions in 41% of patients. The comprehensive Neer classification showed similar intra- and inter-observer reliabilities to AO.