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Pediatric Supracondylar Fractures: Variation in Fracture Patterns and the Biomechanical Effects of Pin Configuration
Todd Jaeblon1, Steven Anthony, Alan Ogden
1*Department of Orthopaedic Surgery, LSU Health-Shreveport ‡Department of Mathematics & Statistics, Louisiana State University-Shreveport, Shreveport, LA †Advanced Orthopedic Center, Charlotte, FL.
Insights
Two lateral pins (2LP) offer optimal stiffness for pediatric supracondylar humerus fractures, outperforming three lateral pins (3LP) and cross K-wires (XP) in most configurations. All-lateral constructs provide adequate stability without ulnar nerve risk.
Area of Science:
- Orthopedic surgery
- Pediatric orthopedics
- Biomechanics
Background:
- Pediatric supracondylar humerus fractures are common.
- Optimal fixation methods require further investigation.
Purpose of the Study:
- To determine the optimal pin configuration for low, sagittal oblique, and high pediatric supracondylar humerus fractures.
- To compare the biomechanical stability of different pin configurations.
Main Methods:
- 100 synthetic pediatric humeri were tested.
- Three fracture variations were simulated.
- Subgroups were stabilized with 2 lateral pins (2LP), 3 lateral pins (3LP), or cross K-wires (XP).
- Anterior-posterior, medial-lateral, and rotational stiffness were measured.
Main Results:
- For low fractures, 2LP and 3LP showed similar stiffness to intact bone, superior to XP.
- For oblique fractures, 2LP demonstrated the greatest stiffness, surpassing 3LP and XP.
- For high fractures, 3LP offered greater rotational stiffness than 2LP and XP.
Conclusions:
- 2LP and 3LP constructs provide superior stiffness compared to XP for most pediatric supracondylar humerus fracture patterns.
- All-lateral pin constructs offer adequate stability and may reduce the risk of ulnar nerve injury.
Background:
Transverse pediatric supracondylar fractures through the midolecranon fossa are frequently encountered and modeled in biomechanical studies. Our objective is to investigate the optimal pin configurations for low, sagittal oblique, and high fracture varieties that have not been previously investigated.
Methods:
A total of 100 synthetic composite pediatric humeri were tested. Three groups of 30 were used to simulate 1 of 3 fracture variations. Subgroups of 10 were stabilized with 2 lateral pins (2LP), 3 lateral pins (3LP), or cross K-wires (XP). The 90 fracture and 10 intact models were tested for anterior posterior (AP), medial lateral (ML), and rotational stiffness.
Results:
In low fractures, AP, ML, and rotational stiffness of 2LP and 3LP were similar to intact. ML stiffness was less using XP. AP and ML stiffness of 2LP and 3LP were significantly greater than XP.In oblique fractures, AP, ML, and rotational stiffness of 2LP was similar to intact but 3LP was significantly less. AP and ML stiffness of XP was significantly less. 2LP demonstrated greater AP, ML, and rotational stiffness than 3LP and XP.In high fractures, all configurations demonstrated significantly less rotational stiffness than intact and AP stiffness similar to intact. Rotational stiffness of 3LP was greater than 2LP and XP. AP and ML stiffness were not different among configurations.
Conclusions:
2LP are stiffer than 3LP and XP for sagittal oblique fractures. 2LP and 3LP stiffness were similar in low transverse fractures, and both constructs demonstrated greater stiffness than XP configuration. 3LP is preferable for high transverse fractures. XP were never stiffer than the lateral only constructs in any of the patterns tested.
Clinical Relevance:
All-lateral pin constructs may provide adequate stiffness to maintain reduction of low transverse, sagittal oblique, and high transverse patterns of pediatric supracondylar humerus fractures without risk of injury to the ulnar nerve.
