Reconstruction Plate Research Articles

Patient-specific Implants Improve Volumetric Surgical Accuracy Compared to Stock Reconstruction Plates in Modern Paradigm Virtual Surgical Planning of Fibular Free Flaps for Head and Neck Reconstruction

BackgroundVirtual surgical planning (VSP) for composite microvascular free flaps has become standard of care for oncologic head and neck reconstruction. Controversy remains as to the use of three-dimensional (3D)-printed titanium patient specific implants (PSI) versus hand-bent stock reconstruction plates. Proponents of PSIs cite improved surgical accuracy, reduced operative times, and improved clinical outcomes. Detractors purport increased cost associated with PSIs and presumed equivalent accuracy with less expensive stock plates. PurposeThe study purpose was to measure and compare the 3D-volumetric accuracy of PSI versus stock reconstruction plates among subjects undergoing VSP-guided mandibular fibular free flap reconstruction. Study Design/Setting/SampleA retrospective cohort study of subjects undergoing VSP-guided fibular free flap reconstructions at Mayo Clinic between 2016-2023 was performed. Subjects were excluded for non-VSP guidance, midfacial reconstruction, non-fibular free flaps, and lack of requisite study variables. Predictor VariableThe primary predictor was the type of reconstruction plate utilized (PSI versus stock plate). Main Outcome VariableThe main outcome was volumetric surgical accuracy of the final reconstruction compared to the preoperative surgical plan by root mean square error (RMSE) calculation. Lower RMSE values indicated a higher surgical accuracy. CovariatesCovariates included age, sex, race, smoking status, ASA classification, Charlson Comorbidity Index, preoperative diagnosis, and number of fibular segments. AnalysisDifferences in surgical accuracy were assessed between pre- and post-operative segmented scans using volumetric overlays from which RMSE values were calculated. Univariate and multivariate modeling of plate type to RMSE calculation was performed. Statistical significance set to p<0.05. ResultsTotal of 130 subjects were identified, 105 PSI and 25 stock plates. Calculated mean RMSE in millimeters (mm) for stock plates was 1.46 (SD: 0.33) and 1.15 (SD: 0.36) for PSIs. Univariate modeling demonstrated a statistically significant difference in RMSE of 0.31 (95% CI: 0.16-0.47) (p<0.001) equating to a 21.2% (p<0.001) improved volumetric surgical accuracy for PSIs. The association of improved volumetric accuracy with PSIs maintained in all multivariate models controlling for confounding. Conclusion and RelevanceIn modern era VSP-guided head and neck fibular free flap reconstruction, patient-specific 3D-printed titanium implants confer a statistically significant improvement in volumetric surgical accuracy over stock reconstruction plates.

Utilizing Euler poles for the evaluation of plate rigidity in numerical mantle convection models

SUMMARY Evidence that the Earth’s surface is divided into a tessellation of piece-wise rigidly translating plates is the primary observation supporting the solid-state creep-enabled convection paradigm, utilized to investigate evolution of the Earth’s mantle. Accordingly, identifying the system properties that allow for obtaining dynamically generated plates remains a primary objective in numerical global mantle convection simulations. The first challenge for analysing fluid dynamic model output for the generation of rigid plates is to identify candidate plate boundaries. Here, we utilize a previously introduced numerical tool for plate boundary detection which uses a user specified threshold (tolerance) to automatically detect candidate plate boundaries. The numerical tool is applied with different sensitivities, to investigate the nature of the surface velocity fields generated in three calculations described in earlier work. The cases examined differ by the values that they specify for the model yield stress, a parameter that can allow the formation of tightly focussed bands of surface deformation. The three calculations we examine include zones comprising possible plate boundaries that are characterized by convergence, divergence and strike-slip behaviour. Importance of the potential plate boundaries is assessed by examining the rigidity of the inferred model generated plates. The rigidity is measured by comparing the model velocities to the rigid rotation velocities implied by the statistically determined Euler poles for each candidate plate. We quantify a lack in rigidity by calculating a deformity field based on disagreement of actual surface velocity with rotation about the Euler pole. For intermediate yield stress and boundary detection threshold value, we find that the majority of the model surface can translate almost rigidly about distinct plate Euler poles. Regions that conform poorly to large-scale region rigid translation are also obtained but we find that generally these regions can be decomposed into subsets of smaller plates with a lower tolerance value. Alternatively, these regions may represent diffuse boundary zones. To clarify the degree to which the mantle convection model behaviour shows analogues with Earth’s current-day surface motion, we apply the plate boundary detection and Euler pole calculation methods to previously published terrestrial strain-rate data. Strong parallels are found in the response of the terrestrial data and mantle convection calculations to the threshold value, such that appropriate choice of that parameter results in very good agreement between observations and convection model character. We conclude that plates generated by fluid dynamic convection models can exhibit motion that is markedly rigid, and define statistics (plateness) and fields (deformity) by which the generation of self-consistently determined plate rigidity can be quantified, as well as describing how plate recognition might be optimized. We also note that in agreement with the Earth’s current state, we obtain a dozen dominant plates in the case exhibiting the most plate-like (rigid) surface, suggesting that this approximate number of plates is perhaps intrinsic to the geometry, surface area and physical properties of Earth’s mantle.

Cretaceous–Paleocene extension at the southwestern continental margin of India and opening of the Laccadive basin: constraints from geophysical data

Abstract. Previous geophysical investigations of the western continental margin of India (WCMI) confirm the two-phase breakup history of the margin with the first breakup taking place between India and Madagascar that created the Mascarene Basin in the Late Cretaceous and the second breakup event in Early Paleocene with Seychelles separating from India. Despite numerous geoscientific studies along the WCMI, the opening of the Laccadive basin, situated along the southern part of the margin, remains poorly constrained. In this study, we evaluate the multi-channel seismic reflection and gravity anomalies at the margin to identify the early rift signatures in conjunction with the magnetic anomaly identifications in the Mascarene Basin. The analysis led to the identification of two trends of extensional structures, a NNW–SSE-oriented structure over the Laccadive Ridge north of Tellicherry Arch, interpreted to result from ENE–WSW extension, and a SSW–NNE-oriented structure in the Laccadive basin region towards the south, interpreted to result from NW–SE extension. Previous plate reconstruction models of the Mascarene Basin using marine magnetic lineations suggest that the ENE–WSW extension observed over the Laccadive Ridge could be related to the India–Madagascar separation. We associate the pattern of sediment deposition and the presence of a Paleocene trap volcanics, linked with the NW–SE grabens observed in the Laccadive basin region, to the extension between the Laccadive Ridge and the western coast of India after the separation of Madagascar from India. We further propose that the anticlockwise rotation of India and the passage of the Réunion plume have facilitated the opening of the Laccadive basin.

Slab buckling as a driver for rapid oscillations in Indian plate motion and subduction rate

Plate tectonics is primarily driven by the constant gravitational pull of slabs where oceanic lithosphere sinks into the mantle at subduction zones. Under stable plate boundary configurations, changes in plate motion are then thought to occur gradually. Surprisingly, recent high-resolution Indian plate reconstructions revealed rapid (2–3 Million-year) plate velocity oscillations of ±50 %. We show, through numerical experiments, that the buckling of slabs in the mantle transition zone causes such oscillations. This buckling results from the deceleration of slabs as they sink into the lower mantle. The amplitude and period of buckling-associated oscillations depend on average subduction velocity and the available space in the mantle transition zone. The oscillations also affect the upper plate which may explain enigmatic observations of episodic deformation and fluid flow in subduction-related orogens. We infer that the slab pull that drives plate tectonics is generated in just the top few hundred kilometers of the mantle.

Management of fractures involving the mandibular body, parasymphyseal, and subcondylar regions

Background: The mandibular bone plays a crucial role in various aspects of facial anatomy, including digestion, speech, and facial aesthetics. Given its significance in these functions, surgeons must not only address functional aspects but also consider aesthetic concerns during treatment. Mandibular fractures represent a prevalent form of traumatic injury in the maxillofacial region. Despite the existence of established treatment methods that have been in use for a considerable time, untreated fractures and complications following surgery can still significantly impact the patient's quality of life. Purpose: Understand the principles of managing cases of mandibular corpus, mandibular parasymphysis, subcondyle fractures using a combination of Mini Plate and Reconstruction Plate. Case: A 54-year-old man with mandibular parasymphysis fracture Dekstra, corpus mandibular fracture sinistra, subcondyle fracture sinistra, dentoalveolar fracture regions 32-42 accompanied by avulsions 32, 31, 41, 42, and hypertension was reported. Results: The treatment in this case was Open Reduction and Internal Fixation (ORIF). Fixation of the fracture segments with 2 vertical mini-plates on the parasymphysis of the dextral mandible, 1 mini-plate and reconstruction plate on the corpus and subcondyle fracture sinistra. Conclusion: The use of two plates and screws in the parasymphysis of the mandible, one mini-plate and one reconstruction plate in mandibular corpus and subcondyle fractures, resulted in good occlusion with minimal complications.

Finite element analysis of reconstruction plates in mandibular defects

Segmental defects in the mandibular bone can occur after local trauma, infection, or surgical resection. Several reconstructive possibilities are currently available, and temporary stabilization of bone segments with reconstruction plates is commonly used when immediate bone reconstruction is not possible. However, little attention has been paid to the biomechanical aspects involved in this approach, and studies conducted with biomodels face the difficulty of simulating the muscular forces involved. The use of Finite Element Analysis allows for the mathematical evaluation of structures in a controlled environment, applying forces at any point and/or direction, assessing material deformation, as well as the tension applied to them. Thus, the aim of this study was to evaluate reconstruction plates used on segmental defects through mathematical analysis using finite elements. After simulation, lower stress values were found on thicker plates, suggesting greater resistance to fracture. Conversely, significantly increased stress values on the screws were present in thicker plates.

Biomechanical Comparison of Fixation Methods for Posterior Wall Fractures of the Acetabulum: Conventional Reconstruction Plate vs. Spring Plate vs. Variable Angle Locking Compression Plate.

Background and Objectives: Acetabular fractures, though infrequent, present considerable challenges in treatment due to their association with high-energy trauma and poor prognoses. Posterior wall fractures, the most common type among them, typically have a more favorable prognosis compared to other types. Anatomical reduction and stable fixation of the posterior wall are crucial for optimal treatment outcomes. This study aimed to biomechanically compare three commonly used fixation methods for posterior wall fractures of the acetabulum-a conventional reconstruction plate, a spring plate, and a 2.7 mm variable angle locking compression plate (VA-LCP). Materials and Methods: The study utilized 6 fresh-frozen cadavers, yielding 12 hemipelvises free from prior trauma or surgery. Three fixation methods were compared using a simple acetabulum posterior wall fracture model. Fixation was performed by an orthopedic specialist, with prebending of plates to minimize errors. Hemipelvises were subjected to quasi-static and cyclic loading tests, measuring fracture gap, stiffness, and displacement under load. Results: It showed no significant differences in fracture gap among the three fixation methods under cyclic loading conditions simulating walking. However, the conventional reconstruction plate exhibited a greater stiffness compared to the spring and variable angle plates. Fatigue analysis revealed no significant differences among the plates, indicating a similar stability throughout cyclic loading. Despite differences in stiffness, all three fixation methods demonstrated adequate stability under loading conditions. Conclusions: While the conventional reconstruction plate demonstrated a superior stiffness, all three fixation methods provided sufficient stability under cyclic loading conditions similar to walking. This suggests that postoperative limitations are unlikely with any of the three methods, provided excessive activities are avoided. Furthermore, the variable angle plate-like the spring plate-offers an appropriate stability for fragment-specific fixation, supporting its use in surgical applications. These findings contribute to understanding the biomechanical performance of different fixation methods for acetabular fractures, facilitating improved surgical outcomes in challenging cases.

Biomechanical considerations of semi-anatomic glass fiber-reinforced (GFRC) composite implant for mandibular segmental defects: A technical note

ObjectivesThe aim of this study was to investigate the selected biomechanical properties of semi-anatomic implant plate made of biostable glass fiber-reinforced composite (GFRC) for mandibular reconstruction. Two versions of GFRC plates were tested in vitro loading conditions of a mandible segmental defect model, for determining the level of mechanical stress at the location of fixation screws, and in the body of the plate. MethodsGFRC of bidirectional S3-glass fiber weaves with dimethacrylate resin matrix were used to fabricate semi-anatomic reconstruction plates of two GFRC laminate thicknesses. Lateral surface of the plate followed the contour of the resected part of the bone, and the medial surface was concave allowing for placement of a microvascular bone flap in the next stages of the research. Plates were fixed with screws to a plastic model of the mandible with a large segmental defect in the premolar-molar region. The mandible-plate system was loaded from incisal and molar locations with loads of 10, 50, and 100 N and stress (microstrain, με) at the location of fixation screws and the body of the plate was measured by strain gauges. In total the test set-up had four areas for measuring the stress of the plate. ResultsNo signs of fractures or buckling failures of the plates were found during loading. Strain values at the region of the fixation screws were higher with thick plate, whereas thin plates demonstrated higher strain at the body of the plate. Vertical displacement of the mandible-plate system was proportional to the loading force and was higher with incisal than molar loading locations but no difference was found between thin and thick plates. ConclusionGFRC plates withstood the loading conditions up to 100 N even when loaded incisally. Thick plates concentrated the stress to the ramus mandibulae region of the fixation screws whereas the thin plates showed stress concentration in the angulus mandibulae region of the fixation and the plate itself. In general, thin plates caused a lower magnitude of stress to the fixation screw areas than thick plates, suggesting absorption of the loading energy to the body of the plate.

Antibiotic bone cement covered reconstruction plate for infected anterior pelvic ring fractures

To explore the clinical efficacy of antibiotic bone cement covered reconstruction steel plate in the treatment of infected anterior pelvic ring fracture. From January 2017 to March 2022, 11 patients with infected anterior pelvic ring fracture were treated with antibiotic bone cement covered reconstruction steel plate including 7 males and 4 females and the age ranged from 27 to 49 years old. The pelvic fractures were classified according to the Tile typology: 4 cases of C1 type, 4 cases of C2 type, and 3 cases of C3 type. Among them, 2 cases of infected anterior ring were infected after internal fixation of anterior ring, and 9 patients were infected with infected anterior ring due to incomplete early debridement, which was classified as infected according to the injury severity score(ISS) for 24 to 38 scores. The anterior ring was internally fixed by extended debridement, irrigation, and antibiotic bone cement covered reconstruction plate, and the posterior ring fractures were all closed reduction and internally fixed with sacroiliac screws. All 11 cases obtained follow-up from 13 to 20 months. Among them, 2 patients had recurrence of postoperative infection, 1 case was re-dissected and replaced with antibiotic bone cement-coated internal fixation, and 1 case had a milder infection without accumulation of the medullary cavity, and the infection was controlled by retaining the plate and replacing the antibiotic bone cement only after dissecting. Two cases developed incisional oozing, which healed after removal of the internal fixation three months postoperatively. All patients did not show pelvic fracture redisplacement or reinfection during the follow-up period. All 11 cases eventually healed bony. At the final follow-up, according to the Matta score, the fracture reduction was excellent in 6 cases, good in 4, and possible in 1. According to the Majeed functional score, it was excellent in 6, good in 3, and possible in 2. Antibiotic bone cement covered reconstruction plate is effective in the treatment of infected anterior pelvic ring fracture, with high intraoperative safety and low recurrence rate of infection, which is conducive to the early postoperative rehabilitation and significantly shortens the course of the disease.

Management of the atrophic mandibular fractures: a ten-year prospective study of 48 injuries.

The purpose of this study was to (a) record and evaluate the epidemiological data relevant to the fractures of the atrophic mandible in the Greek population (b) present our experience in the management of these difficult injuries and (c) compare our results to the outcomes of other similar studies and discuss the postoperative complications. A prospective analysis of all the edentulous patients with fractures of the atrophic mandible treated at the Oral and Maxillofacial Surgery Department of K.A.T General Hospital of Athens in Greece was performed from November 2012 to December 2022. Age, gender and medical history of the patient, etiology and site of the fracture, classification of atrophy, type of surgical approach, type of osteosynthesis and postoperative complication. 34 patients were included in the present study and 48 fractures of the atrophic edentulous mandible were managed surgically. 22 fractures were classified as class II of atrophy, 21 fractures as class III and 5 injuries as class I. In 32 patients we used an extraoral approach and only 2 patients were treated with an intraoral access. 44 fractures were treated with a 2.0mm locking reconstruction plate and only 4 injuries of class I atrophy were treated with mini plates. Clinical practice has confirmed that for these cases an extraoral approach followed by stable fixation with a 2.0mm reconstruction locking plate can deliver excellent results. Our findings show that the routine use of primary bone grafts is not necessary and can be reserved for more complex cases.

On effect of residual stress on fracture behavior of mandibular reconstruction plates

Titanium reconstruction plates are often used to bridge mandibulectomy defects in load bearing scenarios when bone grafts are not well integrated to the host bone. The residual stress within a standard reconstruction plate is generated when being bent and installed to adapt to a patient-specific anatomical contour and it may have a detrimental effect on the structural stability and reliability of the reconstruction system. This study aimed to evaluate the impact of residual stress on the mechanical strength of the reconstructed mandibular system by utilizing both conventional finite element method (FEM) and eXtended Finite Element Method (XFEM). The mechanical stresses introduced by plate pre-bending and screw tightening were first modeled computationally and the residual stress data induced by the surgical procedure was incorporated to the deformed reconstruction plate for the subsequent biomechanical evaluation. Static and cyclic loading conditions were then imposed on the mandibular plate models to further investigate two common failure types, namely overloading fracture and fatigue fracture. It is revealed that the residual stress could considerably increase the susceptibility of plate fracture. The simulation results demonstrate that the pre-stresses induced by screw tightening are more substantial than that from plate bending during the surgical procedure. The finding is of important clinical implications for surgeons who are commonly involved in selecting and preparing different forms of fixation plates for mandibular reconstruction. This study helps elucidate the key factors contributing on the failure of reconstruction plates and guide the development of more robust and durable mandibular reconstruction systems.

Comparison of 2 different fixation techniques of comminuted acetabular quadrilateral surface fractures using square bracket-shaped tubular plate or interfragmentary screws in addition to supra/infrapectineal plate fixation: An observational study.

The management of comminuted quadrilateral fractures remains challenging, and treatment options are constantly evolving. The purpose of the present study was to examine the outcomes of 2 different fixation techniques in the management of comminuted quadrilateral fractures. Twenty-two patients with comminuted quadrilateral acetabular fractures were surgically treated with interfragmentary lag screw (group 1) and square bracket-shaped tubular (SBST) plate technique (group 2), in addition to suprapectineal and infrapectineal pelvic reconstruction plate fixation between January 2016 and July 2019 at our clinic. 2 years follow-up control data of each group were compared in terms of radiological and functional results, and complications. According to the functional score comparison, the mean Merle d'Aubigne Postel scoring system (MAP) score was 15.2/15.6 (P = .632), and the mean Harris hip scoring (HHS) system score was 74.65/77.3 (P = .664) in groups 1 and 2, respectively. Radiological comparison was performed according to matta radiological criteria (MRC), and 2 excellent, 6 good, 2 poor, 4 excellent, 4 good, and 4 poor radiological results were observed in groups 1 and 2, respectively. intraarticular screw penetration was detected in 3 patients in group 1, while there was no articular implant penetration in group 2 (P = .001). We believe that satisfactory results can be obtained with the SBST plate technique, offering functional and clinical outcomes that are similar to those of the interfragmentary screw technique. The SBST plate technique is superior in terms of avoiding intraarticular screw penetration and related revision surgery.

Superior versus anteroinferior plating for mid-shaft clavicle fractures: a randomized clinical trial.

Clavicle fractures represent 2.5-4% of all fractures observed in emergency services. 80% occurs in the middle third. Treatment by plating requires a higher level of evidence. To compare the functional outcomes of mid-shaft clavicle fractures managed with superior plating compared to anteroinferior plating. A randomized, double-blind, parallel, superiority clinical trial. Patients with fractures of the clavicles AO15B1 and AO15B2 were studied. Patients were randomized to be treated with either 3.5 mm superior or anteroinferior plating. A rehabilitation program was designed for both groups. The primary outcome measure was the Disability of Arm, Shoulder, and Hand (DASH) score; secondary outcomes included pain, union rate, and complication rates. Twenty-eight patients were studied and were eligible for analysis. Significant differences were found in the function assessed with the DASH score at 30 days for the superior plating compared with anteroinferior (43.74 vs. 29.26, respectively, p = 0.027), 60 days (23.97 vs. 11.18, p = 0.021), and 90 days (9.52 vs. 3.5, p = 0.016). One loosening with superficial infection was found with superior plating. Using an anteroinferior reconstruction plate in diaphyseal fractures offers better functional results than the upper plate in patients with fractures of the middle third of the clavicle.

Plate tectonic limits on the assembly of cratonic Australia

Continuous Proterozoic plate reconstructions consistent with plate geodynamics were designed to reconcile data, conceptual models, and human imagination as applied to the assembly of the Australian craton. The reconstructions were created using GPlates and considered available magmatic and metamorphic U-Pb zircon data. Two tectonic scenarios for the Paleo- to Mesoproterozoic assembly of the cratonic lithosphere of Australia were tested for their geodynamic and geochronological viability. The scenarios are founded on tectonic events that are relatively well-established and well-supported by data, but also with several periods and areas that are disputed mostly due to scarcity of data. For these scenarios, we test geodynamic criteria to explore a) which possibilities are better supported by our geodynamic criteria, and b) the implications of those models for the larger-scale plate tectonic setting. The time frame in this model set includes assembling two supercontinents, Nuna (1900–1800 Ma) and Rodinia (1300–900 Ma), and the transition between them. Model 1 presents a progressive assembly of the Australian continent between 2000 Ma and 1300 Ma, showing events in the West Australian Craton (WAC), the convergence of the WAC and the North Australian Craton (NAC), and then accretion at the margin of the South Australian Craton and NAC until collision in the Albany-Fraser Orogen (AFO). Model 2 suggests WAC was separate from the rest of the Australian Craton until 1300 Ma and all combined in one orogenic cycle. It proposes Andean-type subduction along the E and NE margins of the WAC for 40–60 million years as the means of final assembly. Both models are geodynamically plausible, yet each lacks sufficient data support to conclusively resolve the differences and deepen our understanding of the Proterozoic assembly of Australia.

On the impact of true polar wander on heat flux patterns at the core–mantle boundary

Abstract. The heat flux across the core–mantle boundary (CMB) is a fundamental variable for Earth evolution and internal dynamics. Seismic tomography provides access to seismic heterogeneities in the lower mantle, which can be related to present-day thermal heterogeneities. Alternatively, mantle convection models can be used to either infer past CMB heat flux or to produce statistically realistic CMB heat flux patterns in self-consistent models. Mantle dynamics modifies the inertia tensor of the Earth, which implies a rotation of the Earth with respect to its spin axis, a phenomenon called true polar wander (TPW). This rotation must be taken into account to link the dynamics of the mantle to the dynamics of the core. In this study, we explore the impact of TPW on the CMB heat flux over long timescales (∼1 Gyr) using two recently published mantle convection models: one model driven by a plate reconstruction and a second that self-consistently produces a plate-like behaviour. We compute the geoid in both models to correct for TPW. In the plate-driven model, we compute a total geoid and a geoid in which lateral variations of viscosity and density are suppressed above 350 km depth. An alternative to TPW correction is used for the plate-driven model by simply repositioning the model in the original paleomagnetic reference frame of the plate reconstruction. The average TPW rates range between 0.4 and 1.8° Myr−1, but peaks up to 10° Myr−1 are observed. We find that in the plate-driven mantle convection model used in this study, the maximum inertia axis produced by the model does not show a long-term consistency with the position of the magnetic dipole inferred from paleomagnetism. TPW plays an important role in redistributing the CMB heat flux, notably at short timescales (≤10 Myr). Those rapid variations modify the latitudinal distribution of the CMB heat flux, which is known to affect the stability of the magnetic dipole in geodynamo simulations. A principal component analysis (PCA) is computed to obtain the dominant CMB heat flux pattern in the different cases. These heat flux patterns are representative of the mantle convection cases studied here and can be used as boundary conditions for geodynamo models.

Modified one third tubular plate (spring plate) augmented with reconstruction plates for treatment of comminuted posterior wall acetabular fractures, Short to midterm outcomes of 24 patients.

To evaluate the clinical and functional outcomes of employing a spring plate augmented by a traditional 3.5 mm reconstruction plate for the treatment of comminuted posterior wall acetabular fractures. A prospective case series was performed on 24 patients with comminuted fractures of the posterior wall. After an average of 6 days, the patients underwent surgery. Eighteen patients were fixed with one spring plate, six patients were fixed with two spring plates, and all were reinforced with a 3.5-mm reconstruction plate. Each case was followed once every three months until the fracture healed and then regularly every six months thereafter. There were 21 men and 3 women. The average follow-up period was 14 months, and the median age was 34.5 years. The main reason for injuries was motor vehicle collisions. The mean operation time was 107.5 min. The clinical results were evaluated by the MAP and m HHS, and the means were 10.2 (5-12) and 86 (64-96), respectively. Only two patients developed avascular necrosis and were treated by total hip replacement, another three (12.5%) had mild arthritis. Comminuted acetabulum posterior wall fractures can be stabilized with spring plates. It could be used in conjunction with the primary reconstruction plate as a viable alternative for stable and anatomical reduction. High patient satisfaction and good functional results make this approach effective.

Biomechanical comparison of an intramedullary nail combined with a reconstruction plate combination versus a single intramedullary nail in unstable intertrochanteric fractures with lateral femoral wall fracture: A finite element analysis.

This study aimed to compare the biomechanical performance of an intramedullary nail combined with a reconstruction plate and a single intramedullary nail in the treatment of unstable intertrochanteric femoral fractures with a fracture of the lateral femoral wall (LFW). A three-dimensional finite element (FE) femur model was established from computed tomography images of a healthy male volunteer. A major reverse obliquity fracture line, associated with a lesser trochanteric fragment defect and a free bone fragment of the LFW, was developed to create an AO/OTA type 31-A3.3 unstable intertrochanteric fracture mode. Two fixation styles were simulated: a long InterTAN nail (ITN) with or without a reconstruction plate (RP). A vertical load of 2100 N was applied to the femoral head to simulate normal walking. The construct stiffness, von Mises stress, and model displacement were assessed. The ITN with RP fixation (ITN/RP) provided higher axial stiffness (804 N/mm) than the ITN construct (621 N/mm). The construct stiffness of ITN/RP fixation was 29% higher than that of ITN fixation. The peak von Mises stress of the implants in the ITN/RP and ITN models was 994.46 MPa and 1235.24 MPa, respectively. The peak stress of the implants in the ITN/RP model decreased by 24% compared to that of the ITN model. The peak von Mises stress of the femur in the ITN/RP model was 269.06 MPa, which was lower than that of the ITN model (331.37 MPa). The peak stress of the femur in the ITN/RP model was 23% lower than that of the ITN model. The maximum displacements of the ITN/RP and ITN models were 12.12 mm and 13.53 mm, respectively. The maximum displacement of the ITN/RP model decreased by 12% compared with that of the ITN model. The study suggested that an additional plate fixation could increase the construct stiffness, reduce the stresses in the implant and femur, and decrease displacement after intramedullary nailing. Therefore, the intramedullary nail and reconstruction plate combination may provide biomechanical advantages over the single intramedullary nail in unstable intertrochanteric fractures with a fractured LFW.

Evaluation of aesthetic outcomes of mandibular reconstruction using artificial intelligence.

Although vascularized bone graft (VBG) transfer is the current standard for mandibular reconstruction, reconstruction with a mandibular reconstruction plate (MRP) and with a soft-tissue flap (STF) alone remain crucial options for patients with poor general conditions. However, objective aesthetic outcome evaluations for these methods are limited. In a retrospective analysis of 65 patients (VBG, 33; MRP, 19; and STF, 13), mandibular asymmetry value was calculated for each patient's photograph using facial recognition AI, with a higher value indicating worse asymmetry. The MRP group had a value comparable to the VBG group regardless of mandibular defect types. The STF group had a significantly higher value than the VBG group. Regarding cosmesis, STF was inferior to VBG, whereas MRP was comparable to VBG, even for anterior defects for which rigid reconstruction is mandatory. However, MRP's risks of plate-related complications limit its use to cases where VBG is contraindicated or with poor prognosis.

Postoperative Rehabilitation with a CAD/CAM-fabricated Occlusal Splint Following Plate Reconstruction after Hemimandibulectomy and Condylectomy: A Case Report.

Mandibular deviation (MD) is a common reconstruction sequela after segmental mandibulectomy. Although proper postoperative rehabilitation is critical for MD management and minimization, the information available is limited. This report describes postoperative rehabilitation with an occlusal splint fabricated using computer-aided design (CAD) and computer-aided manufacturing (CAM) (CAD/CAM-OS) and the results of a threedimensional occlusal analysis using an intraoral scanner after hemimandibulectomy and plate reconstruction. Despite the short follow-up, adherence to postoperative rehabilitation with CAD/CAM-OS for MD correction, even during radiotherapy, was demonstrated by the digital workflow and analysis results.

An Ellipsoidal Plate Motion Model of the Indo‐Australian Tectonic Plate

AbstractWe present a class of “ellipsoidal rotation matrices” which can be used to characterize tectonic plate motion; where geocentric Cartesian coordinates travel along paths tangential to the ellipsoid. We contrast them with conventional Euler pole plate motion models which are more closely aligned with spherical coordinate systems and inherently induce a change in geodetic ellipsoidal height. We demonstrate the use of each in the Indo‐Australian tectonic plate setting, which is known to move approximately 7 cm/year in a north‐northeast direction. Geocentric Datum of Australia 2020 (GDA2020) coordinates are “plate‐fixed” static coordinates obtained using a conventional Euler pole plate motion model to align time dependent coordinates with the 2014 realization of the International Terrestrial Reference Frame at the epoch 2020.0. We show that this Euler pole plate motion model can introduce ellipsoidal height velocities of up to −0.2 mm/year. This is small but systematic, so pertinent for consideration with high accuracy vertical land motion studies using GDA2020 coordinates and velocities. We further investigate the comparative statistical accuracy of conventional Euler pole and the ellipsoidal models with respect to characterizing plate motion captured in high quality Global Navigation Satellite System data.