Comparative stability of perpendicular versus parallel double‐locking plating systems in osteoporotic comminuted distal humerus fractures

Abstract

In distal humerus fractures, the restoration of stability is important to allow early mobilization and hence more favorable functional outcomes. In this article, we compare the biomechanical stability of perpendicular and parallel locking plating systems for the internal fixation of AO Type C2 distal humerus fractures in osteoporotic bone. Fractures were simulated in paired cadaveric bones and fixed using either the perpendicular 3.5 mm LCP distal humerus plating system (Synthes; Sydney, Australia) or the parallel Mayo Clinic Congruent elbow plate system (Acumed; Hillsboro, OR), using locking screws in both systems. Both systems were then tested for their stiffness (in compression and internal/external rotation), plastic deformation, and failure in torsion. Comparatively, the parallel locking plate system provided a significantly higher stability in compression (p ¼ 0.005) and external rotation (p ¼ 0.006), and a greater ability (p ¼ 0.005) to resist axial plastic deformation. Stability for both constructs appeared to be dependent on bone quality, however the stability of the perpendicular system was generally more sensitive to bone mineral density, indicating a possible need for additional independent interfragmentary screws. A disadvantage of the parallel locking plate system was wear debris produced by its tapping system. In summary, the biomechanical findings of this study suggest that both locking plate systems allow early mobilization of the elbow in patients with osteoporotic bone following fixation of a comminuted distal humerus fracture. However, the parallel locking system showed improved stability compared with the perpendicular locking system, and therefore may be more indicated. ß

Distal Humerus Fractures

“…[35][36][37][38][39][40] Several biomechanical studies have demonstrated that parallel plate configurations at 180° to each other are biomechanically superior to perpendicular plates when a gap model is used to simulate fracture comminution. [43][44][45] Two clinical level IV studies have reported on the results of locked plating of distal humerus fractures (n = 52 patients). 46,47 Pooled analysis showed good/excellent results in 79% of patients, with only a single case of implant failure.…”

“…Level II • 1 study 27 Level III • 2 studies 28,29 Level IV • 20 studies [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49] occurs following operative intervention for distal humerus fractures.…”

Orthogonal versus Parallel Plating for Distal Humeral Fractures

“…Self et al, 23) who demonstrated the biomechanical properties of the two systems using reconstruction plates, noted that the parallel system was stronger and stiffer. In their study of 24 humeri with simulated AO type C2 of female cadavers aged between 68 to 87 years of age using locked plates, Stoffel et al 24) demonstrated that stability was dependent on bone quality and noted that the parallel plating system was superior and showed significantly higher stability in compression and external rotation with greater ability to resist axial plastic deformation. Penzkofer et al, 25) in an artificial bone model with simulated AO/OTA type C2-3, noted that the parallel plate demonstrated the highest bending stiffness and median fatigue limit in extension, whereas in flexion, the 90-90 plating demonstrated the highest bending stiffness.…”

Mechanical Strength of the Mayo Clinic Congruent Elbow Plate System for Distal Humerus Fractures: Cadaveric and Model Bone Model

“…There was no major difference between the performance of CL02 and CN02, and maximum torque was reached for both CL01 and CN01. [8][9][10] .…”