The measurements and standardization of humerocondylar angle in children.

Background: Supracondylar fractures of the humerus in children are very common. However, the literature regarding measurements of normal anatomical relationships of the distal humerus in sagittal plane is sparse.

Method: We reviewed the radiographs of normal elbow joints in 142 children treated in our hospital over 2 years. No history of previous trauma of distal humerus was found. The children were separated into 3 age groups (<5, 5-10, and 10-15 years old), and measurement of the humerocondylar angle (HCA) in sagittal plane was performed.

Results: The mean age of children in group 1 was 3 years 1 month; in group 2, 7 years 8 months; and in group 3, 12 years. There were 99 boys and 43 girls. The mean HCA was 41.6 degrees (range, 30-70 degrees). No statistically significant influence on HCA by age, sex, or side was found. We found a small number of extreme variants in HCA (down to 30 degrees and up to 70 degrees) in children without any history of previous trauma and having a normal range of elbow motion.

Conclusions: We found that HCA is close to the well-accepted figure of 40 degrees. Interestingly, this value remains the same in all age groups. That means that the geometry of the distal humerus in sagittal plane is established very early during the growth and remains constant. Due to significant individual variations of HCA, it alone cannot be sufficient for final decisions in evaluation and treatment of supracondylar fractures.