Biomechanical comparison of plating techniques for fractures of the mandibular condyle

Optimal Plate Choice for High-Neck Mandibular Condyle Fracture: A Mechanistic Analysis of 16 Options

(1) Background: Mandibular fractures are common, with the condylar process being a frequent site of injury, accounting for 25-45% of cases. This research aims to assess the mechanical suitability of various plates for high-neck condyle fractures. (2) Methods: Polyurethane models mimicking high-neck condyle fractures were utilized in this study. Sixteen distinct plate designs, constructed from titanium sheets, were tested. The figures underwent force assessments on a durability testing apparatus, and the relationship between used force and fracture movement was documented. (3) Results: For high-neck breaking, the two straight plates emerged as the most effective, aligning with established osteosynthesis standards. The second-best plate exhibited nearly half the strength of the gold standard. (4) Conclusions: In response to the aim of this study, considering the mechanical aspects, the double plain plate stands out as the optimal choice for osteosynthesis in cases of high-neck fractures of the mandibular condylar process. In addition, the authors propose the Mechanical Excellence Factor (MEF) as a superior metric for appraising a plate's mechanical force, surpassing the conventional Plate Design Factor (PDF).

Which of the 37 Plates Is the Most Mechanically Appropriate for a Low-Neck Fracture of the Mandibular Condyle? A Strength Testing

(1) Background: The mandible is the most frequently injured component of the facial skeleton, with 25-45% of mandibular fractures involving the condylar process. This study aims to mechanically compare which plates are most suitable for use in low-neck fractures of the condyle. (2) Methods: Polyurethane mandibular models with simulated low-neck fractures were tested using 37 distinct plate designs. These plates were fabricated from 1 mm thick, grade 23 titanium sheets. The models were then subjected to force tests on a strength machine, and the correlation between applied force and fracture displacement was recorded. (3) Results: For low-neck fractures, XCP side-dedicated 3+5 and ACP-T plates demonstrated strength comparable to that of two straight plates, the current gold standard in osteosynthesis. (4) Conclusions: The Mechanical Excellence Factor (MEF) introduced by the authors provides a more accurate metric for theoretically predicting a plate's mechanical strength compared to the Plate Design Factor (PDF). Eight plate characteristics were utilized to calculate the MEF. Employing the MEF allows for rapid, preliminary validation before undertaking strength tests. Furthermore, the findings of this study can guide the selection of the most durable plate designs for subsequent fatigue testing.

Which of 51 Plate Designs Can Most Stably Fixate the Fragments in a Fracture of the Mandibular Condyle Base?

In the surgical treatment of the most common fracture of the mandible, which is a fracture of the condylar base, a great choice of different plate shapes is observed. The aim of this study was to determine which shape gives the greatest fixation stiffness. To ensure homogeneity in comparison, tests were performed on polyurethane models divided at the level of the condylar base fracture and each were fixed with 51 plates. The plates were cut from a 1 mm thick grade 23 titanium sheet. The models were then loaded and the force required for 1 mm of fracture displacement was recorded. It was noted that in addition to osteosynthesis from two simple plates, there were also two dedicated single plates with similar rigidity. Among the large number of described designs of plates, there is considerable variation in terms of the stability of the fixation performed with them. The proposed Mechanical Excellence Factor allows a pre-evaluation of the expected rigidity of fixation with a given plate shape without the need for a loading experiment. The authors expect this to be helpful for surgeons in the application of relevant plates, as well for inventors of new plates for the osteosynthesis of basal fractures in mandibular condyle.

A, Srivastav S, P.G. G, Kumar P, Chaudhry K. Treatment Outcome Comparison Between two 3-Dimensional Plates (Y-Shaped Plate Versus Trapezoidal Condylar Plate) in Management of Mandible Condylar Fracture: A Randomized Control Trial

Aim

To compare the treatment outcomes (clinical, functional and radiographical) using the two different 3-Dimensional plates in open reduction internal fixation of mandibular condylar fracture (MCF). Assessment of ease of fixation and fixation time were also performed.

Methodology

20 MCF patients were divided equally into two groups (Group A: Trapezoidal Condylar Plate and Group B: Y-shaped plate) and the treatment outcomes were compared. Intraoperatively time required for fixation was also compared. The patients were followed up at different timelines till 3 months.

Result

Baseline parameters had statistically insignificant distribution in both groups implying effective randomization and balanced confounding factors. Intraoperatively, adequate anatomical reduction was achieved in both groups with statistically insignificant difference in time required for fixation. Postoperatively, no statistically significant difference was found in radiographic and functional parameters. None of the patients in either group reported with facial nerve injury, condylar resorption, Temporomandibular Disorders. However, 02 patients in Group A and 01 patient in Group B presented with infection, parotid fistula, and hardware failure respectively with statistically insignificant difference.

Conclusion

This study concluded that the treatment outcomes were satisfactory with the use of both 3-D plate, but further studies with larger sample size and longer follow up are required.

Macaca mulatta is a good model for human mandibular fixation research

Biomechanical and clinical studies have yet to converge on the optimal fixation technique for angle fractures, one of the most common and controversial fractures in terms of fixation approach. Prior pre-clinical studies have used a variety of animal models and shown abnormal strain environments exacerbated by less rigid (single-plate) Champy fixation and chewing on the side opposite the fracture (contralateral chewing). However, morphological differences between species warrant further investigation to ensure that these findings are translational. Here we present the first study to use realistically loaded finite-element models to compare the biomechanical behaviour of human and macaque mandibles pre- and post-fracture and fixation. Our results reveal only small differences in deformation and strain regimes between human and macaque mandibles. In the human model, more rigid biplanar fixation better approximated physiologically healthy global bone strains and moments around the mandible, and also resulted in less interfragmentary strain than less rigid Champy fixation. Contralateral chewing exacerbated deviations in strain, moments and interfragmentary strain, especially under Champy fixation. Our pre- and post-fracture fixation findings are congruent with those from macaques, confirming that rhesus macaques are excellent animal models for biomedical research into mandibular fixation. Furthermore, these findings strengthen the case for rigid biplanar fixation over less rigid one-plate fixation in the treatment of isolated mandibular angle fractures.

Fracture Fixation Technique and Chewing Side Impact Jaw Mechanics in Mandible Fracture Repair

Lower jaw (mandible) fractures significantly impact patient health and well‐being due to pain and difficulty eating, but the best technique for repairing the most common subtype—angle fractures—and rehabilitating mastication is unknown. Our study is the first to use realistic in silico simulation of chewing to quantify the effects of Champy and biplanar techniques of angle fracture fixation. We show that more rigid, biplanar fixation results in lower strain magnitudes in the miniplates, the bone around the screws, and in the fracture zone, and that the mandibular strain regime approximates the unfractured condition. Importantly, the strain regime in the fracture zone is affected by chewing laterality, suggesting that both fixation type and the patient's post‐fixation masticatory pattern—ipsi‐ or contralateral to the fracture— impact the bone healing environment. Our study calls for further investigation of the impact of fixation technique on chewing behavior. Research that combines in vivo and in silico approaches can link jaw mechanics to bone healing and yield more definitive recommendations for fixation, hardware, and postoperative rehabilitation to improve outcomes. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Assessment of biomechanical properties of specially-designed miniplate patterns in a mandibular subcondylar fracture model with finite element analysis and a servohydraulic testing unit

The aim of our study was to compare the biomechanical stability of three different systems used to fix mandibular condylar fractures on synthetic polyurethane mandibles using a servohydraulic testing unit and finite element analysis (FEA). We measured the resistance to displacement loads causing 1.75 and 3.5mm displacements of the fragments, and the maximum resistance values before failure of the fixation system in 30 condylar necks of 15 polyurethane mandible models. The three subgroups investigated were arranged as a triangular plate (n=10), a quadrangular plate (n=10), and a straight miniplate (n=10). The most successful fixation pattern was achieved with two straight four-hole miniplates. However, the triangular plate can easily be applied as a second option by an endoscopic approach. The rectangular plates showed no success in mandibular condylar fractures.

Biomechanical Evaluation of Mandibular Condyle Fracture Osteosynthesis Using the Rhombic Three-Dimensional Condylar Fracture Plate

PURPOSE

The aim of the present study was to evaluate the biomechanical stability of osteosynthesis in mandibular condyle fractures using a newly designed rhombic 3-dimensional (3D) condylar fracture plate and compare it with that using standard two 4-hole miniplates and with that in nonfractured condyles.

MATERIALS AND METHODS

Using 200 porcine mandibles, 3 different monocortical plating techniques were evaluated. The condyles were fractured along a defined line tangentially through the sigmoid notch and perpendicular to the posterior border. After anatomic reduction, osteosynthesis was performed using either standard rhombic 3D condylar fracture plates and standard screws (group A) or locking rhombic 3D condylar fracture plates, which were fixed either with standard screws (group B) or locking screws (group C). For comparison, nonfractured condyles (group D) and condyles fixed with standard two 4-hole miniplates and 8 screws (group E) were included. Using a universal mechanical testing machine (TIRA Test 2720; TIRA GmbH Schalkau, Germany), each group was subjected to linear loading from laterally to medially, medially to laterally, anteriorly to posteriorly, and posteriorly to anteriorly. The maximum axial force and displacement at the maximum force were measured. The mean values were compared for statistical significance using analysis of variance with Bonferroni's correction (statistical significance set at P < .05).

RESULTS

The main mode of failure in the plating techniques investigated was the pull out of screws from the proximal fragment. We found no statistically significant differences in the stability of osteosynthesis between the two 4-hole miniplates and the rhombic 3D condylar fracture plate when loading from posteriorly to anteriorly, laterally to medially, and medially to laterally. However, when loading from anteriorly to posteriorly, a statistically significant difference between the standard and locking system and the two 4-hole miniplate system was observed, with the latter proving more stable.

CONCLUSIONS

The results of the present biomechanical study suggest that the rhombic 3D condylar fracture plates are suitable for the treatment of condylar neck fractures. Both types of the plate are able to resist physiologic strains comparable to the two 4-hole miniplates.

Bioabsorbable plates versus metal miniplate systems for use in endoscope-assisted open reduction and internal fixation of mandibular subcondylar fractures

PURPOSE

To compare bioabsorbable plates with metal miniplate systems for use in endoscope-assisted open reduction and internal fixation (EAORIF) of mandibular subcondylar fractures.

MATERIALS AND METHODS

This retrospective cohort study included patients with mandibular subcondylar fractures treated with EAORIF using bioabsorbable unsintered hydroxyapatite/poly l-lactide composite plates or titanium miniplate systems. The outcome variables included preoperative fracture conditions, postoperative stability during fracture healing, and complications during the follow-up period. Other variables included clinical characteristics (age, sex, fracture site, and total follow-up duration) and intra- and postoperative data (surgical duration, duration of intermaxillary fixation/elastic band guidance). Variables were evaluated using descriptive statistics and compared between groups using the Mann-Whitney test and the chi-square test or Fisher's exact test, as appropriate.

RESULTS

In total, 28 patients were analyzed, including 13 who underwent EAORIF using bioabsorbable plates and 15 who underwent EAORIF using titanium miniplates. With the exception of second surgery for plate removal, none of the assessed variables showed significant differences between the two groups (p < 0.05).

CONCLUSIONS

Our results suggest that EAORIF using biodegradable plates is a stable and reliable method for the management of mandibular subcondylar fractures and eliminates the need for secondary surgery for plate removal.

Comparison of Different Fixation Types Used in Unilateral Mandibular Condylar Fractures: An In Vivo Study With New Biomechanical Model

INTRODUCTION

The aim of this in vivo study is to compare the single-titanium, double-titanium mini plate, and single resorbable plate systems used in internal rigid fixation of the unilateral mandibular condylar fractures on new design biomechanical model.

METHODS

Thirty synthetic polyurethane models were used for biomechanical testing. Fracture lines were created for each model. Fragments were fixed with single-titanium plates in Group A (n = 10), double-titanium plates in Group B (n = 10), and single biodegradable plate (PPLA) in Group C (n = 10). Masticatory forces were applied to the models and the biomechanical properties of the titanium plate and screws, resorbable plate, and screws were evaluated.

RESULTS

The average failure force for Group A, Group B, and Group C is 199, 324, 177N and the average bone displacement for Group A, Group B, Group C is 1.9, 0.3, 2.1 mm, respectively.

DISCUSSION

Double titanium plates showed the most acceptable results in the fixation of unilateral subcondylar fractures where the single titanium and biodegradable plate systems failed to provide enough stability in unilateral subcondylar fracture fixation. Biodegradable plate systems are still not an alternative in fixation of unilateral condylar fractures.

Efficacy of Retromandibular Transparotid Approach for the Management of Extracapsular Subcondylar Mandibular Fractures Using 2-mm Titanium Miniplates: A Prospective Clinical Study

PURPOSE

The aim of this study was to evaluate the long-term clinical and radiologic results of the retromandibular transparotid approach to displaced extracapsular subcondylar mandibular fractures.

PATIENTS AND METHODS

A prospective cohort study was conducted over a period of 5 years on patients surgically treated for displaced extracapsular subcondylar mandibular fractures by the retromandibular transparotid approach. Variables including the type of fracture, degree of mouth opening, fracture displacement, deviation, excursive movements of the mandible, and facial nerve function were monitored before and after treatment. Appropriate statistics were computed.

RESULTS

Thirty-nine patients with 47 fractures were evaluated. There were 34 subcondylar fractures (located below the sigmoid notch) (87%), and 5 fractures were located in the head region in bilateral cases. Of the fractures, 31 (79%) were unilateral and 8 (21%) were bilateral. In a multivariate study, condylar coronal displacement, coronal sagittal displacement, difference in the ramal height, maximal interincisal distance, protrusive movements, and deviation of the mandible on opening showed statistically significant differences in pretreatment and post-treatment patients (P = .001). The interincisal distance was 46.8 mm (SD, 5.2 mm) postoperatively versus 24.1 mm (SD, 6.7 mm) before treatment. The average range of protrusion was significantly lower (P = .001) in patients before treatment, at 1.9 mm (SD, 1.2 mm), when compared with 6.1 mm (SD, 2.0 mm) postoperatively. During mouth opening, deviation of the mandible is often a sign of compensatory movement of the contralateral joint due to shortening of the ascending ramal height on the affected joint. The mean deviation of the mandible from the midline was 4.2 mm (SD, 1.0 mm) in patients before treatment, with a significant difference (P = .001) in patients after treatment, with a mean of 1.9 mm (SD, 0.995 mm). Temporary injuries to the facial nerve branches were observed in 3 cases (8%) 1 week after treatment, which later resolved within 3 weeks to 3 months.

CONCLUSIONS

The retromandibular transparotid approach provides good exposure and facilitates accurate reduction and fixation of the subcondylar fragment with positive outcomes, good cosmetic results, and rare major complications. Most facial nerve injuries are transient in nature after this approach. A Synthes 2-mm titanium single mini-plate (West Chester, PA) provides stable results after fixation.

Finite element analysis of patient-specific condyle fracture plates: a preliminary study

Various patterns of internal fixation of mandibular condyle fractures have been proposed in the literature. This study investigates the stability of two patient-specific implants (PSIs) for the open reduction and internal fixation of a subcondylar fracture of the mandible. A subcondylar fracture of a mandible was simulated by a series of finite element models. These models contained approximately 1.2 million elements, were heterogeneous in bone material properties, and also modeled the muscles of mastication. Models were run assuming linear elasticity and isotropic material properties for bone. The stability and von Mises stresses of the simulated condylar fracture reduced with each of the PSIs were compared. The most stable of the plate configurations examined was PSI 1, which had comparable mechanical performance to a single 2.0 mm straight four-hole plate.

Comparative evaluation of various miniplate systems for the repair of mandibular corpus fractures

Miniplates have been used during the last decade to facilitate stability between bony fragments in the maxillofacial region and are currently the preferred surgical method for the fixation of fractures and osteotomies. The aim of this study was to evaluate and compare the biomechanical behaviors of six different types of miniplates used to reconstruct mandibular body fractures: Group 1 (straight, 2 holes, 12.0 mm spacing), Group 2 (straight, 4 holes, 9.0 spacing), Group 3 (straight, 6 holes, 9.0 mm spacing), Group 4 (L-shaped, 4 holes, 9.0 mm spacing, right hand plate), Group 5 (Y-shaped, 5 holes, 12.0 mm spacing), and Group 6 (double Y-shaped, 6 holes, 9.0 mm spacing). Thirty bovine hemimandibles and a custom-made 3-point biomechanical test frame mounted on a Shimadzu universal test machine were used to evaluate the six different miniplate systems. Results revealed that Group 1 (straight, 2 holes, 12.0 mm spacing) and Group 4 (9.0 mm spacing, right hand plate) had the lowest biomechanical stability, whereas Group 6 (6 holes, 9.0 mm spacing) had the highest biomechanical stability. Group 6 also provided statistically greater resistance to displacement than Group 1 and Group 4.

A Biomechanical Comparison of Three 1.5-mm Plate and Screw Configurations and a Single 2.0-mm Plate for Internal Fixation of a Mandibular Condylar Fracture

The most stable pattern of internal fixation for mandibular condyle fractures is an area of ongoing discussion. This study investigates the stability of three patterns of plate fixation using readily available, commercially pure titanium implants. Finite element models of a simulated mandibular condyle fracture were constructed. The completed models were heterogeneous in bone material properties, contained approximately 1.2 million elements and incorporated simulated jaw adducting musculature. Models were run assuming linear elasticity and isotropic material properties for bone. No human subjects were involved in this investigation. The stability of the simulated condylar fracture reduced with the different implant configurations, and the von Mises stresses of a 1.5-mm X-shaped plate, a 1.5-mm rectangular plate, and a 1.5-mm square plate (all Synthes (Synthes GmbH, Zuchwil, Switzerland) were compared. The 1.5-mm X plate was the most stable of the three 1.5-mm profile plate configurations examined and had comparable mechanical performance to a single 2.0-mm straight four-hole plate. This study does not support the use of rectangular or square plate patterns in the open reduction and internal fixation of mandibular condyle fractures. It does provide some support for the use of a 1.5-mm X plate to reduce condylar fractures in selected clinical cases.

Comparison and validation of finite element analysis with a servo-hydraulic testing unit for a biodegradable fixation system in a rabbit model

The aim of this study was the biomechanical validation of three-dimensional finite element analysis (FEA) with a servo-hydraulic testing unit (STU) for a resorbable fixation system (RFS) in a rabbit model. Bilateral mandibular vertical body osteotomies (BMVBO) were performed in 15 female New Zealand rabbits. The animals were divided into three groups. The STU and FEA tests were done immediately after surgery in group 1 (1 day), at the first postoperative month in group 2, and at the third postoperative month in group 3. Both stress tests were carried out by applying vertical forces at the lower incisal edge, loading from 0 N force and increasing this until breakage occurred at the bone. The maximum forces that the hemimandibles could stand and the amount of deformation were recorded and analysed with the FEA and STU tests. We found the STU and FEA test results to be similar and that they could be used interchangeably for groups 1 and 3. However, the FEA results differed most from the real STU values in group 2 because of callus formation that had not ossified at the osteotomy line.

Review of biomechanical experimental studies on different plating techniques of mandibular condyle fractures

Mandibular condyle fractures are one of the most frequent injuries of the facial skeleton. The option for open treatment of mandibular condyle fractures has become more favorable since osteosynthesis materials were developed in the past few decades. However, the rigid fixation techniques of treating condyle fractures remain one of the controversial issues in maxillofacial trauma. These injuries are currently treated by plate-screw osteosynthesis and, depending on the case, the bone segments are fixed by one or two miniplates. Several techniques and plate types like adaption miniplates, minidynamic compression plates, resorbable plates and double plates have been evaluated biomechanically in various experimental and clinical studies. The biomechanical and physical behavior of mandibles have been investigated by different approaches. It can be divided into computer biomodels (e.g., finite element analysis) and physical models. Physical models allow testing on a gross level to give fatigue performance and fracture strength. The aim of this article is to carry out a review of the literature which deals with biomechanical evaluation made with physical models of plating techniques of mandibular condyle fracture. Based on the results of these studies, osteosynthesis with two miniplates seems to be the most stable way of treating mandible subcondylar fractures, and PLLA plates were not strong enough compared with metal plates.

The treatment of condylar fractures: to open or not to open? A critical review of this controversy

The treatment of condylar process fractures has generated a great deal of discussion and controversy in oral and maxillofacial trauma and there are many different methods to treat this injury. For each type of condylar fracture, the techniques must be chosen taking into consideration the presence of teeth, fracture height, patient's adaptation, patient's masticatory system, disturbance of occlusal function, deviation of the mandible, internal derangements of the temporomandibular Joint (TMJ) and ankylosis of the joint with resultant inability to move the jaw, all of which are sequelae of this injury. Many surgeons seem to favor closed treatment with maxillomandibular fixation (MMF), but in recent years, open treatment of condylar fractures with rigid internal fixation (RIF) has become more common. The objective of this review was to evaluate the main variables that determine the choice of method for treatment of condylar fractures: open or closed, pointing out their indications, contra-indications, advantages and disadvantages.

Biomechanical comparison of different plating techniques in repair of mandibular angle fractures

OBJECTIVE

The purpose of this study was to evaluate the biomechanical behaviors of different miniplate fixation techniques for treatment of fractures of the mandibular angle.

STUDY DESIGN

Twenty sheep hemimandibles were used to evaluate 4 different plating techniques. The groups were fixated with Champy technique, biplanar plate placement, monoplanar plate placement, and 3-dimensional (3D) curved angle strut plate. A custom-made 3-point biomechanical test model was used for the samples. Each group was tested with compression forces by an Instron Lloyd LRX machine. The biomechanical behavior of the groups for the forces (N) that caused displacement of 1.75 mm were compared using the Instron software program and displacement graphics.

RESULTS

The variance analyses showed that biplanar plate placement had more favorable biomechanical behavior than Champy technique and monoplanar plate placement (P < .05). In addition, the 3D curved angle strut plate technique had more favorable biomechanical behavior than the Champy technique (P < .05) but was not significantly different from biplanar or monoplanar plate placement techniques (P > .05).

CONCLUSION

The study demonstrated that 3D strut plates or dual miniplate techniques had greater resistance to compression loads than the Champy technique. In addition, biplanar plate orientation may provide a more favorable biomechanical behavior than monoplanar plate placement.