The humeral head ratio and neck-shaft angle can be used evaluate a humerus following proximal fracture.
Radiographs are taken in an posterioranterior view with the shoulder in the neutral position.
Parameters measured for both the left and right humeri:
(1) diameter of the proximal head in cm
(2) radius of the articular part of the humeral head = length of a perpendicular line drawn from the midpoint of the diameter line to the articular surface
(3) neck shaft angle = angle between a line running down the middle of the humeral canal and a line extending the radius line (from parameter 2)
humeral head ratio =
= (radius in cm) / ((diameter in cm) / 2) =
= (radius in cm) / (0.5 * (diameter in cm))
For normal humeri the humeral head ratio and neck shaft angle on both the left and right sides should be comparable.
difference in neck shaft angles in degrees =
= (neck shaft angle for injured humerus) - (neck shaft angle for normal humerus)
humeral head collapse ratio =
= (humeral head ratio for the normal side) - (humeral head ratio for the injured side)
Limitation:
• The values cannot be determined if both humeri are injured unless pre-injury radiographs are available.
• The presence of concurrent diseases (osteoathritis, osteoporosis, other) could affect the values.
Specialty: Surgery, orthopedic
ICD-10: ,