Flexible Intramedullary Nail Placement in Pediatric Humerus Fractures
Authors: Gomez Robert W. , McHugh Riley C. , Shukla Dhairya , Greenhill Dustin A. 
Published: November 2024

Background:
Flexible intramedullary nailing is an effective method of stabilization in pediatric patients with a humeral shaft fracture when surgery is indicated
1–3
. Although these fractures are most often treated nonoperatively, operative indications include open fractures, bilateral injuries, compartment syndrome, pathologic fractures, neurovascular compromise, unacceptable alignment after attempted nonoperative treatment, and ipsilateral upper-extremity injuries
4
. The current literature on flexible intramedullary nailing of the pediatric humeral shaft lacks concise descriptions of available entry points, which directly affect the subsequent technique, and of pertinent pediatric-specific anatomy. Thus, the present article focuses on these entry points in the pediatric patient.

Description:
Various entry points are available for the insertion of flexible nails into the humeral shaft. A surgeon must initially decide whether the patient and fracture characteristics are best suited for anterograde versus retrograde insertion. This choice typically depends on several fracture and patient-related characteristics. The passage of flexible intramedullary nails has been well described; thus, the present article will place special emphasis on the available proximal and distal entry points and pediatric-specific anatomy
5–10
. For diaphyseal fractures, we prefer dual distal lateral entry points with the nails advanced retrograde in a C-S configuration whenever possible, given the risks associated with proximal lateral entry (e.g., damage to the axillary nerve) or distal medial entry (e.g., damage to the ulnar nerve or nail prominence). A distal posterior supracondylar entry point is also possible but requires additional preoperative planning with regard to patient positioning, a more proximal entry point to avoid impingement of the olecranon on the nail in extension, and avoidance of the ulnar nerve.

Alternatives:
The substantial potential for remodeling in pediatric patients permits nonoperative treatment of humeral fractures if specific age-related criteria for angulation and displacement are met. Generally accepted tolerances for nonoperative angulation and displacement are as follows: for patients <5 years old, ≤70° angulation and up to 100% displacement; for patients 5 to 12 years old, 40° to 70° angulation; and for patients >12 years old, ≤40° angulation and 50% apposition
4
.

Rationale:
The use of flexible nails is often preferred because of the healing potential of pediatric humeral shaft fractures, the ability of flexible nails to tolerate nonrigid fixation until osseous bridging occurs, the ability of the surgeon to avoid exposure of neurologic structures during surgery, and the benefit of avoiding physeal disruption. These factors make flexible nails a favorable option when compared with plate osteosynthesis or rigid intramedullary nailing.

Expected Outcomes:
When indicated, the use of flexible intramedullary nails in pediatric humeral fractures has been associated with high rates of union, good functional outcomes, early range of motion, and an acceptably low rate of complications
2
.

Important Tips:

Be familiar with the technical details associated with all available entry points.Avoid damage to key neurologic structures around the proximal and distal humerus.Minimize the opportunity for symptomatic hardware.Optimize the biomechanics through flexible nail positioning at the fracture site.

Acronyms and Abbreviations:

FIN = flexible intramedullary nailingEBL = estimated blood lossf/u = follow-upIM = intramedullaryMRI = magnetic resonance imagingOR = operating roomPT = physical therapyROM = range of motion