The Baumann Angle: An Analysis from Theory to Practice.

Objective To analyze how the Baumann angle (BA) is affected by inadequate radiographic inclinations. Methods The study was performed from radiographs of the distal humerus of children aged 3 to 10 years. The BA measurements performed by five observers were compared, and each radiograph was evaluated for its quality as "adequate" or "inadequate." The correlation between radiographic quality and the normality of the angles was evaluated. Results Sample was composed of 141 patients, 44% between 3 and 6 years of age and 56% between 7 and 10. We observed the BA between 52.01 and 89.82 degrees, with about 16% of the measurements outside the normal limits of the literature. A total of 33.3% of the evaluated radiographs were classified as "inadequate". On the BA measurements outside the normality parameter, we observed that its proportion was higher among images with inadequate radiographic quality (31.1 vs. 6.2%), and this difference was significant ( p < 0.001). Conclusions The BA is a very variable measurement and, alone, it is unreliable for the evaluation of angular deformities of the pediatric elbow, with radiographic quality proven to be an important causal factor of this variability.

The Baumann Angle: An Analysis from Theory to Practice / O ângulo de Baumann: Uma análise da teoria à prática

Abstract Objective To analyze how the Baumann angle (BA) is affected by inadequate radiographic inclinations. Methods The study was performed from radiographs of the distal humerus of children aged 3 to 10 years. The BA measurements performed by five observers were compared, and each radiograph was evaluated for its quality as "adequate" or "inadequate." The correlation between radiographic quality and the normality of the angles was evaluated. Results Sample was composed of 141 patients, 44% between 3 and 6 years of age and 56% between 7 and 10. We observed the BA between 52.01 and 89.82 degrees, with about 16% of the measurements outside the normal limits of the literature. A total of 33.3% of the evaluated radiographs were classified as "inadequate". On the BA measurements outside the normality parameter, we observed that its proportion was higher among images with inadequate radiographic quality (31.1 vs. 6.2%), and this difference was significant (p< 0.001). Conclusions The BA is a very variable measurement and, alone, it is unreliable for the evaluation of angular deformities of the pediatric elbow, with radiographic quality proven to be an important causal factor of this variability.

Resumo Objetivo Analisar como o ângulo de Baumann (AB) é afetado por inclinações radiográficas inadequadas. Métodos Estudo realizado a partir de radiografias do úmero distal de crianças de 3 a 10 anos. Foram comparadas as aferições do AB realizadas por cinco observadores, e cada radiografia foi avaliada quanto à sua qualidade em "adequada" ou "inadequada". A correlação entre a qualidade radiográfica e a normalidade dos ângulos foi avaliada. Resultados Amostra composta por 141 pacientes, 44% entre 3 e 6 anos e 56% entre 7 e 10. Observamos AB entre 52,01 e 89,82 graus, tendo cerca de 16% das medidas fora dos limites de normalidade da literatura. Um total de 33,3% das radiografias avaliadas foram classificadas como "inadequadas". Sobre as medidas do AB fora do parâmetro da normalidade, observamos que sua proporção foi maior entre as imagens com qualidade radiográfica inadequada (31,1% vs. 6,2%), tendo essa diferença se mostrado significativa (p< 0,001). Conclusões O AB é uma medida muito variável e, isoladamente, pouco confiável para a avaliação de deformidades angulares do cotovelo pediátrico, tendo a qualidade radiográfica se mostrado um fator causal importante dessa variabilidade.

The trochlear physeal line angle: a novel method to assess coronal plane alignment of the paediatric distal humerus.

Supracondylar humeral fractures account for 60% of elbow fractures in childhood, with cubitus varus being its most common complication. It can be avoided by accurate assessment of distal humeral alignment after fracture reduction, and the Baumann angle is the usual measurement for this purpose. However, several reports demonstrate an inconsistency of this angle, and our hypothesis is that reliability could be improved with angles drawn between the trochlear physeal line and the humeral longitudinal axis. The aim of the study was to compare intra- and interobserver reliability between the Baumann angle and angles drawn between the trochlear physeal line and (1) humeral longitudinal axis (X-angle), (2) humeral lateral cortex line (Y-angle), (3) humeral medial cortex line (Z-angle). Angle measurements were performed on 141 distal humerus' radiographs of children aged 3-10 years by five observers in a tertiary hospital. The measurements were compared for their intra- and interobserver agreement. All measurements showed good or excellent intraobserver agreement levels, with the highest for Z-angle [intraclass correlation coefficient (ICC) = 0.906] and the lowest for Baumann angle. There were also excellent interobserver agreement levels for all angles, the highest for Z-angle (ICC = 0.885). There are indications that Z-angle had higher agreement levels when compared to the others (ICC = 0.954; 0.936-0.969) in the group aged 7-10 years. The angle drawn between the humeral medial cortex and trochlear physeal line showed greater agreement than the other angles analysed, becoming a potentially useful tool for evaluation of children with supracondylar humeral fractures in daily practice.