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Displaced pediatric supracondylar humerus fractures: biomechanical analysis of percutaneous pinning techniques
Steven S Lee1, Andrew T Mahar, Doug Miesen
1Children's Hospital and Health Center, San Diego, California 92123, USA.
Insights
Divergent lateral pins offer superior stability for pediatric supracondylar humerus fractures compared to parallel pins. This technique provides comparable stability to crossed pins in most tests, while potentially reducing ulnar nerve injury risks.
Area of Science:
- Orthopedic surgery
- Pediatric orthopedics
- Biomechanics
Background:
- Supracondylar humerus fractures are common in children.
- Displaced fractures often require closed reduction and percutaneous pinning.
- Debate exists regarding optimal pinning techniques, primarily crossed versus lateral pins.
Purpose of the Study:
- To biomechanically compare the stability of crossed, parallel lateral, and divergent lateral pinning techniques.
- To evaluate fixation strength under various physiological loading conditions.
Main Methods:
- A pediatric synthetic bone model was used for biomechanical testing.
- Three pin configurations (crossed, parallel lateral, divergent lateral) were tested.
- Mechanical testing included extension, varus, valgus, and rotational loads.
Main Results:
- Divergent lateral pins demonstrated significantly greater stability than parallel pins under varus and valgus stress.
- Divergent pins showed comparable stability to crossed pins in extension, varus, and valgus tests.
- Crossed pins provided superior stability during axial rotation testing.
Conclusions:
- Divergent lateral pinning offers enhanced stability over parallel lateral pins for pediatric supracondylar humerus fractures.
- This technique achieves stability comparable to crossed pins in key loading scenarios.
- Divergent lateral pins may offer a safer alternative to crossed pins by avoiding potential ulnar nerve complications.
Abstract:
Supracondylar humerus fractures are a common childhood occurrence. Displaced fractures are typically treated with closed reduction and percutaneous pinning. Controversy continues over the appropriateness of various pinning techniques. The most common include crossed or lateral pins. A biomechanical comparison of crossed pins, "parallel" lateral pins, and "divergent" lateral pins was performed using a pediatric synthetic bone model. Mechanical testing of each pin configuration was performed in extension, varus, valgus, internal rotation, and external rotation. The divergent configuration provided statistically greater stability than parallel pins under varus and valgus loading. Divergent pins had similar stability compared with crossed pins in extension, varus, and valgus testing. In axial rotation testing, crossed pins were more stable. If the surgeon feels confident in the ability of lateral pins to provide satisfactory fracture stability, divergent lateral pins provide greater stability than parallel lateral pins while avoiding ulnar nerve injury (associated with crossed pins).