Biomechanical analysis on the coronoid process fracture merging radial head comminuted fracture

[Objective] To determine the elbow joint stability in the coronoid process fracture and the coronoid process fracture merging radial head comminuted fracture by a mechanical experimental analysis.[Method]Eight pairs of upper limbs of embalmed anatomic specimens were selected, the eversion displacements and the external rotation angles in different coronoid process fractures and coronoid process fractures merging radial head comminuted fractures were measured. The differences between them were recorded.[Result] No significant difference was found among the non-fracture, the type I fracture and the type II fracture, but the elbow eversion displacement in the type III fracture significantly increased.[Conclusion] According to the result of the experiment, the elbow eversion and external rotation are stable under the condition of the coronoid process fracture merging the radial head comminuted fracture in the type I and the type II fractures, thus the radial head excision can be performed safely. By contrast, it is unstable in the type III fracture, extra operation should be taken to repair the radial head or make the prosthetic replacement while repairing the ligamentum collaterale radiale at the same time.