Transcortical Screw Fixation of the Olecranon Shows Equivalent Strength and Improved Stability Compared With Tension Band Fixation

Abstract

Objectives: 

Currently, the standard for 21-B3.1 olecranon fracture fixation is the tension band wire construct described by the AO foundation. Although this technique effectively repairs displaced olecranon fractures and osteotomies, it is associated with a high rate of secondary surgery for implant removal due to hardware “back out,” prominence, and discomfort. The senior author of this study has used transcortical screw fixation for olecranon fractures and osteotomies to avoid hardware discomfort but has been unable to find literature documenting the strength of this method. Accordingly, we compared the strength and stability of transcortical screw fixation with tension band fixation of simple transverse olecranon fractures under cyclical loading.

Methods: 

Eighteen fourth-generation synthetic biomechanical testing ulnas underwent a transverse olecranon osteotomy and were repaired by tension banding or screw fixation. Two 4.0 mm partially threaded screws inserted across the fracture gap into the anterior cortex of the ulna achieved screw fixation. Ulnas were tested in 2 ways as follows: (1) cyclic loading that simulated pushing up from a chair; and (2) single cycle loading to failure. Fracture displacement was recorded using a transducer that was placed on the posterior surface of the ulna.

Results: 

Differences between screw fixation and tension banding in the peak displacement during cyclic loading and single cycle load to failure were not significant. Screw fixation did show significantly less “trough” displacement (resting position between cycles) during cyclic loading indicating less plastic deformation.

Conclusions: 

In a synthetic bone model of simple transverse olecranon fractures, screw fixation provided equivalent strength and less plastic deformation as compared with tension banding.