Partial olecranon excision: the relationship between triceps insertion site and extension strength of the elbow.

摘要

PURPOSE: Partial excision with triceps reattachment is an accepted method for treating comminuted fractures of the olecranon. The currently recommended site for reattachment is along the articular margin of the remaining olecranon process. With computer models suggesting that this may lead to weakness of elbow extension, this study was performed to evaluate different sites for triceps reattachment with respect to extension strength of the elbow. METHOD: Ten fresh frozen human cadavers were potted and the elbow placed in varying degrees of flexion (45 degrees, 90 degrees, and 135 degrees ). Incremental loads were applied to the triceps mechanism and the force generated was recorded using an Instron materials testing machine (Instron Corp., Canton, MA). A 50% olecranon excision was then performed, simulating a comminuted olecranon fracture. The triceps tendon was attached either anteriorly along the articular margin or posteriorly along the cortical margin. All specimens were tested at both insertion sites in random order. RESULTS: A significant decrease in extension strength was observed between intact specimens and anterior attachment of the triceps tendon at all angles of elbow flexion. A decrease was only observed with posterior reattachment at 90 degrees. Posterior reattachment provided greater extensor strength than anterior attachment, with greatest differences seen at increasing positions of elbow extension. CONCLUSIONS: Although anterior reattachment of the triceps tendon after partial excision of the olecranon is currently recommended by some, this results in diminished strength of the triceps mechanism. A greater mechanical advantage with increased strength is provided by a more posterior reattachment using the technique described. These differences are greatest at increasing positions of elbow extension where triceps strength is more functionally important.