Abstract
IntroductionWhen the application of a free vascularised flap is not possible, a segmental mandibular defect is often reconstructed using a conventional reconstruction plate. Mechanical failure of such reconstructions is mostly caused by plate fracture and screw pull‐out. This study aims to develop a reliable, mechanically superior, yet slender patient‐specific reconstruction plate that reduces failure due to these causes.Patients and MethodsEight patients were included in the study. Indications were as follows: fractured reconstruction plate (2), loosened screws (1) and primary reconstruction of a mandibular continuity defect (5). Failed conventional reconstructions were studied using finite element analysis (FEA). A 3D virtual surgical plan (3D‐VSP) with a novel patient‐specific (PS) titanium plate was developed for each patient. Postoperative CBCT scanning was performed to validate reconstruction accuracy.ResultsAll PS plates were placed accurately according to the 3D‐VSP. Mean 3D screw entry point deviation was 1.54 mm (SD: 0.85, R: 0.10–3.19), and mean screw angular deviation was 5.76° (SD: 3.27, R: 1.26–16.62). FEA indicated decreased stress and screw pull‐out inducing forces. No mechanical failures appeared (mean follow‐up: 16 months, R: 7–29).ConclusionReconstructing mandibular continuity defects with bookshelf‐reconstruction plates with FEA underpinning the design seems to reduce the risk of screw pull‐out and plate fractures.
Highlights
When the application of a free vascularised flap is not possible, a segmental mandibular defect is often reconstructed using a conventional reconstruction plate
Contrary to the majority of PS-reconstruction plate (RP) suggested in the literature, which typically consist of a strip-like plate following the buccal contour of the mandible, we focused on incorporating the osteotomy sites of the mandibular segments for stable fixation of the plate
The finite element analysis (FEA) results showed that the maximum von Mises stresses in all the analysed conventional RPs exceeded their yield strength (YS), by 42% up to 153%, indicating plastic deformation would occur on applying the load case
Summary
When the application of a free vascularised flap is not possible, a segmental mandibular defect is often reconstructed using a conventional reconstruction plate Mechanical failure of such reconstructions is mostly caused by plate fracture and screw pull-out. Conclusion: Reconstructing mandibular continuity defects with bookshelf-reconstruction plates with FEA underpinning the design seems to reduce the risk of screw pull-out and plate fractures. When a patient's general medical condition does not allow for this type of reconstructive surgery, the mandibular continuity defect can be bridged using solely a conventional reconstruction plate (RP). This type of RP usually needs manual bending to match the contour of the mandible. According to Maurer et al, (2010), all screw loosening occurred within the first 6 months postoperatively
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