Supracondylar elbow fractures are common in children. Most require close reduction and percutaneous pin fixation. The optimum technique of pin placement remains controversial. Previous studies have established that crossed pins provide better rotational stability then parallel lateral and divergent lateral pin constructs. However, no study compared the addition of a third lateral pin which has become popular in clinical practice. This study developed a model simulating medial comminution using synthetic humeri to establish the torsional stability of various pin configurations. Biomechanical testing was performed on a sawbones model. Medial comminution was simulated by removing a piece of medial bone. Torsional stability was calculated.
In the intact medial column group, greater torsional stability was achieved with two lateral divergent and one medial crossed pin. The second most stable construct was three lateral pins followed by standard crossed pins. Specimens with medial comminution demonstration less torsional stability. Again, the two lateral divergent with a medial crossed pin configuration had the greatest torsional stability. The two lateral divergent pin configurations had the least torsional stability.
The benefits of medial pin fixation remain controversial. Ulnar nerve injuries have been reported. The results of this study show that three lateral divergent pins achieved superior fixation compared to crossed pin fixation in fractures with an intact medial column. As expected, the results also showed less torsional stability with medial comminution, regardless of pin fixation. Two lateral divergent pins with a medial pin is the strongest pin configuration for torsional stability in these instances. However, three lateral divergent pins have equal stability compared to the standard medial and lateral crossed pin configuration. These results support two lateral divergent pins with an addition of a third lateral pin for those fractures with medial comminution. In injuries without medial comminution lateral pin configuration is adequate and safer.
Pediatric, Elbow, Humerus, Supracondylar, Fracture, Pins, Stability