Aims: This computational study evaluated the biomechanical performance of asymmetric metaphyseal cones in managing large type 2a bone defects from osteoporotic tibial plateau fractures.
Methods: Using a pre-existing finite element model of a synthetic medium-sized tibia, six defect patterns with 50 mm cemented stems were analyzed under walking (WA) and stair descending (SD) loads. Models varied in cone unsupported ratios (Ru = 0%, 16%, 32%) and four bone quality levels (stiffness at 100%, 80%, 60%, and 40% of normal values). Gap healing thresholds (0 to 50 μm) were evaluated to assess bone-implant contact areas. Additional long-stem configurations (100 mm) were analyzed for severe osteoporotic conditions.
Results: At 50 μm gap healing threshold, severe defects (Ru = 32%) achieved maximum geometrically possible contact area of 55%, while no-defect bone (Ru = 0%) reached 100%. Maximum micromotion (89 μm) remained below the critical osseointegration threshold of 150 μm, but interface area experiencing elevated micromotion (50 to 90 μm) increased markedly with deteriorating bone quality. High-strain regions formed at the inferior cone surface and stem base, with up to 16% of cancellous bone exceeding yield thresholds in severe osteoporotic models during SD. Long-stem configurations reduced supraphysiological strain volume by 47% compared to the short stem, but induced strain concentrations at the stem terminus. Medial defects generated higher strains than lateral configurations but exhibited more uniform strain distribution patterns.
Conclusion: Metaphyseal cones provide adequate biomechanical stability for tibial plateau fractures in osteoporotic bone. The findings suggest that gap healing enables maximal bone-implant contact within geometrical constraints, supporting the clinical use of these implants with appropriate patient selection and postoperative management.
© 2026 Ren et al.