Septal aperture is the absence of a septum in the coronoid-olecranon fossae of the distal humerus. It is a relatively common anatomic variant in human distal humeri thought to occur early in childhood. We report a case of this atypical fracture in a teenage boy.
Case report
A 16-year-old healthy boy tripped while running, landed on his outstretched left forearm and felt immediate pain in his left elbow. A plain radiograph showed an intercondylar fracture through a septal aperture of his left distal humerus (Fig. 1). The intra-articular fracture exited distally through the trochlear groove and extended proximally through the medial column.
FIG. 1. Plain radiograph shows an intercondylar fracture through a septal aperture in the distal humerus.
Through a posterior approach, the fracture was treated with open reduction and internal fixation with an olecranon osteotomy under general anesthesia. Intraoperatively, the fracture was found to be rotationally unstable. An anti-glide configuration with a 2-hole semitubular plate was placed over the apex of the fracture to add stability. Postoperatively, the fracture healed without complication, and the boy had almost full range of motion of the elbow at 10 weeks. Subsequent follow-up showed continued improvement in elbow function. Then, approximately 14 months after the left humeral fracture, he took an innocuous fall on the ice while playing hockey and suffered an intra-articular T-type fracture to his right distal humerus (Fig. 2). The fracture was once again through a septal aperture and required open reduction and internal fixation. Like his left distal humeral fracture, this one was also rotationally unstable, but involved both medial and lateral columns. Through a posterior approach, 2 contoured 12-hole reconstruction plates were fixed over the 2 columns. This dual plate fixation combined with a transverse lag screw through the trochlea gave adequate compression and stability to the fracture. On further follow-up, no other complications were noted, and the boy gradually regained near-normal function of his right elbow.
FIG. 2. Intra-articular T-type fracture to the right distal humerus through a septal aperture.
Discussion
A septal aperture is thought to occur early in childhood from excessive cancellous bone resorption in the distal humerus.1 One anthropologic study of 872 pairs of humeri in an American population estimated its prevalence at 6%.2 Another study showed bilateral involvement in one-third of specimens examined.1 Consequently, the bony defect acting as a stress-riser may play a significant role in altering fracture patterns and selecting appropriate management. It may also increase susceptibility to a fracture on the affected arm secondary to relatively low-energy trauma.
The bilateral distal humeral fractures in our case report occurred in a healthy young male, on 2 separate occasions. Normally, a substantial force is required for an intercondylar fracture to occur in adults.3 The magnitude of force inferred from the mechanism of injury is disproportionately small considering the extent of the fractures. A septal aperture is associated with decreased robustness, smaller humeral diameter and a narrower canal diameter.4,5 We believe the septal apertures, in his otherwise healthy humeri, probably acted as stress-risers from which these atypical fractures originated following a low-energy impact.
The consequence of septal apertures and distal humeral fractures has been previously addressed in a study by Kuhn and associates.3 Their series was based on fractures sustained by healthy young adults (mean age 15 yr), similar to our case. However, the bilateral fractures we describe here demonstrate that these injuries should not necessarily be considered stable as suggested in their study. We contend that a more rigid construct of fixation such as multiple reconstruction plates with or without a lag screw may be necessary to ensure acceptable healing and full recovery of the patient's elbow function. We also emphasize the importance of patient education regarding a possible increased risk of future low-energy fractures. Finally, we believe the contralateral extremity should be evaluated for the presence of an aperture in order to educate the patient regarding the risks.
Competing interests: None declared.
Correspondence to: Dr. Deenesh T. Sahajpal, 2F-295 Park Ave. South, New York, NY 10010; dtsahajpal@yahoo.com
References
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- 2.Trotter M. Septal apertures in the humerus of American whites and negroes. Am J Phys Anthropol 1934;19:213-27.
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