Abstract Title

Biomechanical Comparison of Three Different Constructs For Transverse Olecranon Fractures

RAD Assignment Number

1619

Presenter Name

John McElroy, MD

Abstract

OBJECTIVE: To compare the biomechanical properties of three different constructs for fixation of transverse olecranon fractures.

BACKGROUND: The gold standard treatment for transverse olecranon fractures is tension band wiring. While this construct has a high rate of union and excellent functional results, a significant disadvantage is irritation from the implant, resulting in rates of secondary surgical procedures as high as 71%. If another treatment option could result in the same functional outcomes without the implant irritation and need for a second procedure, this could have profound implications with regards to cost savings.

METHODS: 42 fourth generation biomechanical sawbones of the proximal ulna were obtained and a simple, reproducible transverse fracture of the olecranon was created. The fracture was then fixed with either tension band wiring, a cannulated 6.5 mm screw with a washer, or a 7.5 mm headless compression screw. The constructs were then tested biomechanically to evaluate strength of fixation by load to failure.

RESULTS: 2 of the headless compression screw constructs were not able to be tested, leaving 12 in that group, and 14 in each of the other two groups. The average load to failure was not significantly different between the three groups (417 N, 449 N, and 451 N for the headless compression screws, cannulated screws, and tension band wiring constructs respectively).

CONCLUSIONS: All constructs had similar strength of fixation as measured by load to failure in the Sawbones model and are well above normal physiologic loads. Costs of hardware removal can be significant, and a reasonable alternative to the standard tension band wiring may be fixation with a headless compression screw. A clinical trial with in-vivo analysis would be the next step for determining if this is a viable fixation method.

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Biomechanical Comparison of Three Different Constructs For Transverse Olecranon Fractures

OBJECTIVE: To compare the biomechanical properties of three different constructs for fixation of transverse olecranon fractures.

BACKGROUND: The gold standard treatment for transverse olecranon fractures is tension band wiring. While this construct has a high rate of union and excellent functional results, a significant disadvantage is irritation from the implant, resulting in rates of secondary surgical procedures as high as 71%. If another treatment option could result in the same functional outcomes without the implant irritation and need for a second procedure, this could have profound implications with regards to cost savings.

METHODS: 42 fourth generation biomechanical sawbones of the proximal ulna were obtained and a simple, reproducible transverse fracture of the olecranon was created. The fracture was then fixed with either tension band wiring, a cannulated 6.5 mm screw with a washer, or a 7.5 mm headless compression screw. The constructs were then tested biomechanically to evaluate strength of fixation by load to failure.

RESULTS: 2 of the headless compression screw constructs were not able to be tested, leaving 12 in that group, and 14 in each of the other two groups. The average load to failure was not significantly different between the three groups (417 N, 449 N, and 451 N for the headless compression screws, cannulated screws, and tension band wiring constructs respectively).

CONCLUSIONS: All constructs had similar strength of fixation as measured by load to failure in the Sawbones model and are well above normal physiologic loads. Costs of hardware removal can be significant, and a reasonable alternative to the standard tension band wiring may be fixation with a headless compression screw. A clinical trial with in-vivo analysis would be the next step for determining if this is a viable fixation method.