![]() ![]() Note that the normal carrying angle of the left arm is 0 degrees. C, With the arms extended, a 25-degree varus deformity of the right arm can be seen in a 9-year-old boy 2 years after a supracondylar fracture of the right arm. On the right, the bone prominences (black dots) can be seen to have tilted medially. B, Change in the carrying angle is apparent, however, when the flexed elbows are examined posteriorly. Aebi 1 observed that the measurements were not constant and changed as the child matured, tending to decrease in magnitude and in variation between children.įIGURE 14-3 A, Change in the carrying angle cannot be detected when the flexed elbows are examined from in front. 1, 17, 77 Smith 77 noted that, of 150 children aged 3 to 11, the carrying angle in boys averaged 5.4 degrees and ranged from 0 to 11 degrees, whereas in girls, it averaged 6 degrees and ranged from 0 to 12 degrees. The normal elbow is usually in slight valgus alignment, but this feature varies among children. The carrying angle of the elbow joint is the angle formed by the intersection of the longitudinal axis of the arm and the forearm ( Fig. Lippincott, 1983.)īecause angular deformity is a common complication of these fractures, the normal variations in pediatric anatomy should be understood. (From Rang, M.: Children’s Fractures, 2nd ed. The better the reduction, the greater the security. ![]() After reduction, the soft tissues hold the fragments in place. Research by Khare et al 45 has confirmed the importance of the triceps tendon’s acting as a tension band to achieve fracture stability in the flexed elbow.įIGURE 14-2 An experimentally produced fracture shows the medial periosteal hinge and offers a glimpse of the posterior hinge. The thickened periosteum of a young child, both medially and laterally, is an important additional stabilizer of the fracture fragment and provides a medial or lateral hinge during attempted reduction ( Fig. 33, 61, 66 Soft tissue stability on the lateral aspect of the elbow is provided by an expansion of the triceps, anconeus, brachioradialis, and extensor carpi radialis longus. The stability of the elbow derives from bony and soft tissue structures. Knowledge of elbow anatomy is important to understanding the cause of the injury, and to understanding effective treatment principles (see Chapters 2 and 3). (From Ogden, J.: Skeletal Injury in the Child. B, However, if a cut is made through the supracondylar foramen, the “bicolumnar” nature of this region becomes evident, looking proximally ( C) and distally ( D). The shaft diameter is large above the supracondylar foramen. 62, 63įIGURE 14-1 A, Transverse and sagittal sections of the distal humerus. The distinctive shape of the humeral metaphysis with the medial and lateral condyles and columns, and the narrow midpoint of the olecranon fossa, adds to the instability of the fracture, particularly when there is rotation and tilting of the distal fragment. ![]() The tip of the olecranon acts as a fulcrum, causing the fracture to occur through the relatively thin bone of the olecranon fossa ( Fig. 60 Hyperextension converts what would be an axial loading force to the elbow into a bending moment. This mechanism has been confirmed by research suggesting that a fall on a hyperextended elbow produces a supracondylar humerus fracture, whereas a fall on an outstretched arm without elbow hyperextension is more likely to cause a distal radius fracture. Traditional teaching has held that the peak incidence for extension-type supracondylar humerus fractures occurs at approximately age 7 because that is the age of maximum elbow flexibility and hyperextension. * Previous reports have suggested that supracondylar fractures are common in boys, but more recent studies have documented an equal sex distribution. The peak age for supracondylar humerus fracture has been reported to be between ages 6 and 7 years, and the left arm is injured more frequently than the right. 41, 50 Eliason 25 reported that 84% of supracondylar fractures occurred in patients younger than 10 years. Supracondylar humerus fractures almost exclusively affect the immature skeleton.
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