The Baumann Angle: An Analysis from Theory to Practice

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.

Keywords
elbow joint; humeral fractures; radiography; child

Measures	Average	SD	ICC
Observer 1
Med. 1	71.61	5.85
Med. 2	71.38	5.98
Med. 3	70.63	5.96
Baumann			0.863
Observer 2
Med. 1	70.11	6.07
Med. 2	69.81	5.70
Med. 3	69.67	5.69
Baumann			0.909
Observer 3
Med. 1	71.15	6.69
Med. 2	70.48	6.34
Med. 3	69.95	6.42
Baumann			0.876
Observer 4
Med. 1	70.27	5.44
Med. 2	70.51	4.84
Med. 3	69.78	5.20
Baumann			0.764
Observer 5
Med. 1	70.90	6.43
Med. 2	71.78	6.22
Med. 3	72.01	6.72
Baumann			0.911

Observers	Average	SD	ICC	Confidence Interval (ICC. 95%)
Observers	Average	SD	ICC	Inf.	Sup.
Baumann			0.843	0.800	0.879
Observer 1	71.20	5.66
Observer 2	69.86	5.65
Observer 3	70.52	6.22
Observer 4	70.19	4.75
Observer 5	71.56	6.28

Measure versus Observer	Baumann angle within normal limits
	No		Yes
	n	%	n	%
Measure 1
Observer 1	22	15.6%	119	84.4%
Observer 2	25	17.7%	116	82.3%
Observer 3	30	21.3%	111	78.7%
Observer 4	18	12.8%	123	87.2%
Observer 5	28	19.9%	113	80.1%
Total (n = 705)	123	17.4%	582	82.6%
Measure 2
Observer 1	24	17.0%	117	83.0%
Observer 2	23	16.3%	118	83.7%
Observer 3	22	15.6%	119	84.4%
Observer 4	16	11.3%	125	88.7%
Observer 5	22	15.6%	119	84.4%
Total (n = 705)	107	15.2%	598	84.8%
Measure 3
Observer 1	19	13.5%	122	86.5%
Observer 2	23	16.3%	118	83.7%
Observer 3	26	18.4%	115	81.6%
Observer 4	20	14.2%	121	85.8%
Observer 5	27	19.1%	114	80.9%
Total (n = 705)	115	16.3%	590	83.7%

	Radiographic quality
	Adequate		Inadequate
Baumann: measure 1
Mean and SD	71.64	5.02	69.15	7.61
Minimum and maximum	56.74	89.82	52.01	87.17
Median and quartiles	71.67	68.8–74.81	69.62	63.39–74.18
Baumann: measure 2
Mean and SD	71.55	4.73	69.28	7.43
Minimum and maximum	55.00	84.56	53.04	85.78
Median and quartiles	71.90	68.66–74.67	69.35	63.5–73.94
Baumann: measure 3
Mean and SD	71.21	4.91	68.80	7.66
Minimum and maximum	57.02	85.87	52.38	88.03
Median and quartiles	71.21	68–74.41	68.71	63.28–73.96

	Radiographic quality				p-value
	Adequate		Inadequate		p-value
Baumann					<0.001
Outside the reference parameters	29	6.2%	73	31.1%
Normal	441	93.8%	162	68.9%

Comparison	Average	95% CI		p-value
Comparison	Average	Inferior	Superior	p-value
Baumann				<0.001
3 to 6 years	71.13	70.44	71.82
7 to 10 years	70.31	69.80	70.83

Sociedade Brasileira de Ortopedia e Traumatologia Al. Lorena, 427 14º andar, 01424-000 São Paulo - SP - Brasil, Tel.: 55 11 2137-5400 - São Paulo - SP - Brazil
E-mail: rbo@sbot.org.br

Acompanhe os números deste periódico no seu leitor de RSS

[1] Address for correspondence Talissa O. Generoso, MD, Departamento de Ortopedia e Traumatologia, Hospital Israelita Albert Einstein, Av Albert Einstein, 627, Consultório 310, Bloco A1, Jardim Leonor, São Paulo, SP, 05652-900, Brasil, talissa.generoso@outlook.com