Olecranon tip osteoarticular autograft transfer for irreparable coronoid process fracture: a biomechanical study.

Background: We hypothesized that transfer of the olecranon tip for simulated type III coronoid fracture would restore posterior ulnohumeral translation to a level not different from that in the intact state.

Methods: The collateral ligaments were left intact in 12 fresh-frozen cadaveric elbows, and all other soft tissues were removed. The entire coronoid process was osteotomized flush with the ventral aspect of the ulna and was reconstructed using the tip of the olecranon process. Specimens were tested with an axial load of 100 N at 0.25 mm/s in 15° increments from 15 to 120° of flexion. Intact, osteotomized, and reconstructed posterior ulnohumeral displacement was measured.

Results: The bony reconstruction did not obstruct range of motion of the elbow. Intact translation (mean ± SD) ranged from 0.3 ± 0.1 to 1.1 ± 0.6 mm, and translation in the osteotomized state ranged from 1.3 ± 1.0 to 2.0 ± 1.0 mm. Resection of the coronoid resulted in a significant increase in posterior ulnar translation compared with intact at all flexion angles (p < 0.05) except at 75°. Reconstruction decreased translation versus the osteotomized state at all flexion angles, significantly at 60 and 120°. No significant difference in translation was found between reconstructed and intact states at five of eight positions tested.

Conclusions: In this biomechanical study of irreparable coronoid fracture, autograft olecranon tip transfer restored posterior elbow stability to a level not significantly different from the intact elbow in five of eight elbow positions tested.