One size may not fit all: patient-specific computational optimization of locking plates for improved proximal humerus fracture fixation

Schader, Jana Felicitas; Mischler, Dominic; Dauwe, Jan; Richards, R. Geoff; Gueorguiev, Boyko; Варга, П.

doi:10.1016/j.jse.2021.06.012

Cited by 11 publications

(6 citation statements)

References 34 publications

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“…Extended fractures with a C-component of the metaphyseal shaft according to the AO/OTA classification demonstrated higher rates of displacement and revision after treatment with nail osteosynthesis due to the high torsional forces of the deltoideus and pectoralis major prevailing in this region [ 7 ]. Plating may therefore neutralize these forces and moments due to the various options for proximal and metaphyseal screw placement, as well as the ability to provide external splinting [ 11 , 21 ]. The results reveal that a secondary displacement or malunion in the metaphyseal region has a significant negative influence on the outcome (CMS-K score) of FHS osteosynthesis.…”

Section: Discussionmentioning

confidence: 99%

Combined Humeral Head and Shaft Fractures: Outcome Following Intramedullary Nailing and Plating

et al. 2023

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Background and Objectives: Combined fractures of the humeral head and shaft (FHS) are rare but frequently involve an intermuscular fracture as its characteristic pattern. The aim of this retrospective study was to investigate intramedullary nailed and plated FHS in terms of outcomes and complications. Materials and Methods: The present study included patients with FHS, treated via either intramedullary nailing or plating within a period of 10 years, with a minimum follow-up of 12 months. Functional outcome was assessed using the age- and sex-adapted Constant–Murley Score (CMS-K). Rates of complications and revision surgeries were registered. Results: Twenty-five patients (18 females, 7 males, age 60.1 ± 14.2 years, range 23–76 years) were included in the study. Nailing was performed in 16 patients (12 females, 4 males, age 62.6 ± 12.4 years), whereas plating was executed in nine patients (6 females, 3 males, age 55.8 ± 17.0 years). Follow-up among all patients was 45.1 ± 26.3 months (range 12–97 months). CMS-K was 70.3 ± 32.3 in the nailing group, with reoperation in four cases, and 76.0 ± 31.0 in the plating group, with one reoperation (p = 0.42). Patients with no metaphyseal fragment displacement (n = 19; CMS-K 76.7 ± 17.3) demonstrated significantly better functional outcomes versus those with secondary displacement of the metaphyseal fragments (n = 6; CMS-K 60.0 ± 17.1), p = 0.046. Conclusions: Comparable acceptable clinical outcome is obtained when comparing nailing with additional open cerclage or lag-screw fixation techniques versus plating with open reduction. However, a higher revision rate was observed after nailing. The correct metaphyseal fragment fixation seems to be crucial to avoid loss of reduction and hence the need for revision surgery, as well as a worse outcome.

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Section: Discussionmentioning

confidence: 99%

Combined Humeral Head and Shaft Fractures: Outcome Following Intramedullary Nailing and Plating

et al. 2023

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“…The finite element analysis may provide information about the optimal screw orientation in the predicted morphology. This improves fixation stability in PHFs and reduces mechanical failures [46]. Moreover, the humeral SSM model could be used for calculating regional defects after fracture reduction.…”

Section: Discussionmentioning

confidence: 99%

Prediction of the Proximal Humerus Morphology Based on a Statistical Shape Model with Two Parameters: Comparison to Contralateral Registration Method

van Schaardenburgh,

Nguyen,

Magré

et al. 2023

Bioengineering

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(1) Background: Complex proximal humerus fractures often result in complications following surgical treatment. A better understanding of the full 3D displacement would provide insight into the fracture morphology. Repositioning of fracture elements is often conducted by using the contralateral side as a reconstruction template. However, this requires healthy contralateral anatomy. The purpose of this study was to create a Statistical Shape Model (SSM) and compare its effectiveness to the contralateral registration method for the prediction of the humeral proximal segment; (2) Methods: An SSM was created from 137 healthy humeri. A prediction for the proximal segment of the left humeri from eight healthy patients was made by combining the SSM with parameters. The predicted proximal segment was compared to the left proximal segment of the patients. Their left humerus was also compared to the contralateral (right) humerus; (3) Results: Eight modes explained 95% of the variation. Most deviations of the SSM prediction and the contralateral registration method were below the clinically relevant 2 mm distance threshold.; (4) Conclusions: An SSM combined with parameters is a suitable method to predict the proximal humeral segment when the contralateral CT scan is unavailable or the contralateral humerus is unhealthy, provided that the fracture pattern allows measurements of these parameters.

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“…Accordingly, the changes in screw trajectories compared with the original design were kept symmetric. Side-specific implants may achieve higher benefits and subject-specific designs may further improve performance ( Schader et al, 2021 ). These were not considered in this study due to logistical challenges.…”

Section: Discussionmentioning

confidence: 99%

“…Beyond the analysis of existing implants, FE simulations can be utilized to explore the possibility of improving fixation stability by adapting design features. In recent in silico studies, the predicted cut-out failure risk could be significantly reduced by optimizing the screw trajectories of a fixed-angle locking plate ( Mischler et al, 2020b ) and further benefits were observed using patient-specific implants ( Schader et al, 2021 ). The underlying FE analysis methodology was validated to predict experimental cyclic cut-out failure of locked plating of unstable three-part proximal humerus fractures (R 2 = 0.90, N = 19) ( Varga et al, 2017 ).…”

Section: Introductionmentioning

confidence: 99%

Locking Plates With Computationally Enhanced Screw Trajectories Provide Superior Biomechanical Fixation Stability of Complex Proximal Humerus Fractures

Mischler

Schader

Dauwe

et al. 2022

Front. Bioeng. Biotechnol.

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Joint-preserving surgical treatment of complex unstable proximal humerus fractures remains challenging, with high failure rates even following state-of-the-art locked plating. Enhancement of implants could help improve outcomes. By overcoming limitations of conventional biomechanical testing, finite element (FE) analysis enables design optimization but requires stringent validation. This study aimed to computationally enhance the design of an existing locking plate to provide superior fixation stability and evaluate the benefit experimentally in a matched-pair fashion. Further aims were the evaluation of instrumentation accuracy and its potential influence on the specimen-specific predictive ability of FE. Screw trajectories of an existing commercial plate were adjusted to reduce the predicted cyclic cut-out failure risk and define the enhanced (EH) implant design based on results of a previous parametric FE study using 19 left proximal humerus models (Set A). Superiority of EH versus the original (OG) design was tested using nine pairs of human proximal humeri (N = 18, Set B). Specimen-specific CT-based virtual preoperative planning defined osteotomies replicating a complex 3-part fracture and fixation with a locking plate using six screws. Bone specimens were prepared, osteotomized and instrumented according to the preoperative plan via a standardized procedure utilizing 3D-printed guides. Cut-out failure of OG and EH implant designs was compared in paired groups with both FE analysis and cyclic biomechanical testing. The computationally enhanced implant configuration achieved significantly more cycles to cut-out failure compared to the standard OG design (p < 0.01), confirming the significantly lower peri-implant bone strain predicted by FE for the EH versus OG groups (p < 0.001). The magnitude of instrumentation inaccuracies was small but had a significant effect on the predicted failure risk (p < 0.01). The sample-specific FE predictions strongly correlated with the experimental results (R2 = 0.70) when incorporating instrumentation inaccuracies. These findings demonstrate the power and validity of FE simulations in improving implant designs towards superior fixation stability of proximal humerus fractures. Computational optimization could be performed involving further implant features and help decrease failure rates. The results underline the importance of accurate surgical execution of implant fixations and the need for high consistency in validation studies.

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One size may not fit all: patient-specific computational optimization of locking plates for improved proximal humerus fracture fixation

Cited by 11 publications

References 34 publications

Combined Humeral Head and Shaft Fractures: Outcome Following Intramedullary Nailing and Plating

Combined Humeral Head and Shaft Fractures: Outcome Following Intramedullary Nailing and Plating

Prediction of the Proximal Humerus Morphology Based on a Statistical Shape Model with Two Parameters: Comparison to Contralateral Registration Method

Locking Plates With Computationally Enhanced Screw Trajectories Provide Superior Biomechanical Fixation Stability of Complex Proximal Humerus Fractures

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