Biomechanical comparison of screw osteosyntheses and anatomical plating for coronoid shear fractures of the ulna

Abstract

Introduction Among the few techniques described for the treatment of coronoid fractures, osteosynthesis techniques include screw osteosynthesis from anterior to posterior (AP) or from posterior to anterior (PA) and plate osteosynthesis. The aim of this study was to test the biomechanical stability of screw osteosynthesis and plate osteosynthesis using anatomical plates in coronoid process fractures. Materials and methods On a total of 25 biomechanical synthetical ulnae, a coronoid shear fracture including 70% of the coronoid height was simulated. Osteosynthesis was then performed using two 2.7 mm screws from anterior, posterior and with use of three different anatomical plates of the coronoid process. For the biomechanical testing, axial load was applied to the fragment with 1000 cycles from 5 to 250 N, load to failure and load at 100 µm displacement. Displacements were measured using a point-based three-dimensional motion analysis system. Results Osteosynthesis using the PA-screw showed significant more displacement during cyclic loading compared with all other osteosyntheses (0.99 mm), whereas AP-screw showed the smallest displacement (0.10 mm) during cyclic loading. The PA-screw technique showed a significant lower load to failure compared to all other osteosynthesis with the highest load in AP-screw osteosynthesis. The load for 100 µm displacement was the smallest in PA-screw with a significant difference to the AP-screw and one plate osteosynthesis. Conclusion Osteosynthesis of large coronoid shear fractures with two small-fragment screws from anterior allows stable fixation that is not inferior to anterior plate osteosynthesis and might be an alternative in specific fracture types. Posterior screw fixation was found as the weakest fixation method. Level of evidence Basic science study

Treatment of Ulnar Coronoid Process Fracture Using the Anterior Neurovascular Interval Approach: A Retrospective Clinical Study with Short‐ to Mid‐term Follow‐up

“…Biomechanical studies have revealed that the posterior axial stability remains largely unaffected in coronoid process fractures, affecting less than 50% of the coronoid plane, provided that there is no severe damage to other auxiliary elbow joint structures. Conversely, compared with intact elbows, fractures encompassing more than 50% of the coronoid plane demonstrate notable posterior axial displacement 8,9 . Moreover, the coronoid process stabilizes the elbow against varus and valgus stresses, preventing posteromedial or posterolateral rotational instability, respectively 8 …”

“…Conversely, compared with intact elbows, fractures encompassing more than 50% of the coronoid plane demonstrate notable posterior axial displacement. 8 , 9 Moreover, the coronoid process stabilizes the elbow against varus and valgus stresses, preventing posteromedial or posterolateral rotational instability, respectively. 8 …”

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“… 21 Further, a biomechanical comparison study of screw osteosynthesis and anatomical plating found that the plate osteosynthesis had better stability for large coronoid shear fractures. 22 However, in cases of coronoid fractures with comminution, the plate or suture could not provide enough stability individually. 6 , 23 Both of them cannot provide three‐dimensional stability of the coronoid fracture fragments.…”

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