German Congress of Orthopaedics and Traumatology (DKOU 2025)
Evaluating the biomechanical efficacy of 2.5+2.0 double plating against 3.5 single plating in Ulna shaft fracture fixation: A cadaveric study
2AO Research Institute, Davos, Schweiz
3Department of Orthopaedics and Traumatology, Bürgerspital Solothurn, Solothurn, Schweiz
4Medical Faculty, University of Zurich (UZH), Department of Orthopaedic and Trauma Surgery, Lucerne Cantonal Hospital, Lucerne, Schweiz
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Objectives and questions: The main postoperative complications in fixation of ulna shaft fractures are non-union and implant irritation. Current standards recommend 3.5-mm locking compression plates, that can cause soft tissue irritation in patients, which may necessitate the secondary removal of implants. An alternative approach using a combination of two smaller plates in orthogonal configuration, has been proposed to overcome the shortcomings of the 3.5-mm plates. The aim of this study is to compare the biomechanical properties of a single 3.5-mm locking compression plate versus double-plating using one 2.5-mm and one 2.0-mm matrix mandible plate in a human ulna shaft fracture model.
Material and methods: Eight pairs human ulnar specimens with a standardized 10 mm comminuted fracture gap were pairwise assigned for instrumentation with either double plating using a 2.5-mm and a 2.0-mm mandible plate placed posteriorly under the flexor muscles and laterally under the extensor muscles, or with a single 3.5-mm plate placed posteriorly. All constructs underwent biomechanical testing for axial, torsional, and bending stiffness, which was followed by cyclic torsional loading to failure. Interfragmentary movements were monitored by means of optical motion tracking.
Results: There were no significant differences between double-plating and single-plating techniques in axial stiffness (464.6±424.0 N/mm vs. 754.2±575.2 N/mm; p=0.335), torsional stiffness in supination (0.330±0.072 Nm/° vs. 0.403±0.066 Nm/°; p=0.462) or pronation (0.330±0.071 Nm/° vs. 0.406±0.068 Nm/°; p=0.307), medio-lateral bending stiffness (1.40±0.61 Nm/° vs. 0.97±0.45 Nm/°; p=0.522), and antero-posterior bending stiffness (0.80±0.01 Nm/° vs. 0.85±0.18 Nm/°; p=0.143). Double-plating showed a higher angular displacement rate during cyclic torsional loading (p=0.03), but no significant difference in shear displacement across the fracture gap (p=0.324). Cycles until failure (5° angular deformation) were 1366±685 for double-plating and 2024±958 for single plating. Both constructs failed due to bone breakage at the most distal screw.
Discussion and conclusions: The new double-plate construct offers equivalent fixation for ulna shaft fractures to 3.5 single plating, with similar stiffnesses and shear displacement during cyclic torsional loading. However, randomized clinical trials are needed to determine if thinner implants reduce irritation rates and require fewer implant removals.
