Biomechanical consequences of coronoidectomy on mandibular condylar stress distribution under simulated traumatic loading: a comparative finite element analysis

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The coronoid process is a major temporalis insertion site and may contribute to load distribution within the mandibular ramus–condyle complex. Coronoidectomy is well established for restoring mouth opening in trismus and ankylosis, but its biomechanical consequences for condylar stress distribution remain incompletely characterized. Using finite element analysis (FEA), we quantified, in a single-specimen comparative model, the change in condylar stress distribution after unilateral coronoidectomy under three simulated traumatic loading scenarios. Two heterogeneous three-dimensional mandibular models — an intact control and a unilateral (right-sided) coronoidectomy model — were reconstructed from a standard anatomical atlas and meshed with tetrahedral elements (908,126 and 918,980 elements). Cortical bone, cancellous bone, teeth, and periodontal ligament were modelled as discrete, homogeneous, isotropic, linear-elastic materials, without masticatory muscle forces, TMJ disc/capsule, or opposing occlusal contacts. A 2000 N load was applied to the symphysis (midline), parasymphysis, and angulus (both ipsilateral to the coronoidectomy), with the condyle constrained in all six degrees of freedom. Analyses were linear static (Abaqus); peak Von Mises, maximum principal (Pmax), and minimum principal (Pmin) stresses were extracted from the condylar neck bilaterally. In this single-specimen comparison, coronoidectomy increased condylar Von Mises stress on the operated (right) side under every loading condition: frontal, 149.1→210.5 MPa (+ 41.2%); oblique, 185.8→242.2 MPa (+ 30.4%); lateral, 379.9→435.0 MPa (+ 14.5%). Pmax and Pmin rose concurrently. Contralateral stress increased modestly under frontal and oblique loading but decreased under lateral loading (− 11.2%); because all non-midline loads were applied ipsilateral to the coronoidectomy, this asymmetry cannot be attributed to the structural change alone. Absolute magnitudes exceeded commonly cited cortical bone ultimate-strength values and are reported strictly as comparative indices of stress concentration, not validated fracture thresholds. Within this single-specimen, simplified model, removal of the coronoid process altered stress distribution in the ramus–condyle complex under the loading and boundary conditions tested, consistent with a structural load-sharing role. These findings are hypothesis-generating; the model does not simulate bone failure and should not be extrapolated to clinical fracture-risk prediction without physiologically more complete, experimentally validated models.

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