Total hip arthroplasty for adults with sequelae from childhood hip disorders poses significant challenges due to altered anatomy. The paper published by Oommen et al reviews the essential management strategies for these complex cases. This article explores the integration of finite element analysis (FEA) to enhance surgical precision and outcomes. FEA provides detailed biomechanical insights, aiding in preoperative planning, implant design, and surgical technique optimization. By simulating implant configurations and assessing bone quality, FEA helps in customizing implants and evaluating surgical techniques like subtrochanteric shortening osteotomy. Advanced imaging techniques, such as 3D printing, virtual reality, and augmented reality, further enhance total hip arthroplasty precision. Future research should focus on validating FEA models, developing patient-specific simulations, and promoting multidisciplinary collaboration. Integrating FEA and advanced technologies in total hip arthroplasty can improve functional outcomes, reduce complications, and enhance quality of life for patients with childhood hip disorder sequelae.

Finite element (FE) models have emerged as a powerful method to study biomechanical complexities of velopharyngeal (VP) function. However, existing models have overlooked the active contributions of the lateral pharyngeal wall (LPW) in VP closure. This study aimed to develop and validate a more comprehensive FE model of VP closure to include the superior pharyngeal constrictor (SPC) muscle within the LPW as an active component of VP closure.

The geometry of the velum and the lateral and posterior pharyngeal walls with biomechanical activation governed by the levator veli palatini (LVP) and SPC muscles were incorporated into an FE model of VP closure. Differing muscle activations were employed to identify the impact of anatomic contributions from the SPC muscle, LVP muscle, and/or velum for achieving VP closure. The model was validated against normative magnetic resonance imaging data at rest and during speech production.

A highly accurate and validated biomechanical model of VP function was developed. Differing combinations and activation of muscles within the LPW and velum provided insight into the relationship between muscle activation and closure patterns, with objective quantification of anatomic change necessary to achieve VP closure.

This model is the first to include the anatomic properties and active contributions of the LPW and SPC muscle for achieving VP closure. Now validated, this method can be utilized to build robust, comprehensive models to understand VP dysfunction. This represents an important advancement in patient-specific modeling of VP function and provides a foundation to support development of computational tools to meet clinical demand.

Impact loads applied to the human head can result in skull fractures or other injuries that require a craniectomy. The removed portion is replaced with biological or synthetic materials using cranioplasty surgery. Titanium has been the material of choice for cranial implants due to its superior properties and biocompatibility; however, its issues have prompted the search for substitute materials (e.g., polymers). The issues are related to the requirement for surface modification, casting, radiologic incompatibility and potential allergy risks. Recently, polymeric materials have been used in many fields as alternatives to titanium.

This research aims to conduct a finite element study to evaluate the skull reconstruction process by using PEEK and carbon fiber reinforced PEEK 30 and 60% in the production of cranial implants as alternatives to conventional titanium implants.

A three-dimensional model of a defective skull was rehabilitated with a custom-made cranial implant. The implants were stimulated using two designs (plate and mesh), and different polymeric materials (PEEK and carbon fiber reinforced PEEK 30 and 60%) as titanium substitutes, under 2000 N impact force.

The results illustrated that plate implants reduced the stresses on the skull and increased the stresses on brain tissues compared to mesh implants. Titanium, CFR-PEEK 30 & 60% implants (whether mesh or flat) were not prone to fracture, unlike mesh PEEK implants. In addition, CFR-PEEK 60% implants produced the lowest values of stress, strain, and total deformation on the skull and brain compared to titanium implants, unlike PEEK implants. By using the titanium plate implant, the peak tensile and compressive stresses on the skull were 24.99 and 25.88 MPa, respectively. These stresses decreased to 21.6 and 24.24 MPa when using CFR-PEEK 60%, increased to 26.07 and 28.99 MPa with CFR-PEEK 30%, and significantly increased to 41.68 and 87.61 MPa with PEEK. When the titanium mesh implant was used, the peak tensile and compressive stresses on the skull were 29.83 and 33.86 MPa. With CFR-PEEK 60%, these stresses decreased to 27.77 and 30.57 MPa, and with CFR-PEEK 30% and PEEK, the stresses increased to 34.04 and 38.43 MPa, and 44.65 and 125.67 MPa, respectively. For the brain, using the titanium plate implant resulted in peak tensile and compressive stresses of 14.9 and 16.6 Pa. These stresses decreased to 13.7 and 15.2 Pa with CFR-PEEK 60%, and increased to 16.3 and 18.1 Pa, and 73.5 and 80 Pa, with CFR-PEEK 30% and PEEK, respectively. With the titanium mesh implant, the peak tensile and compressive stresses were 12.3 and 13.5 Pa. Using CFR-PEEK 60%, these stresses decreased to 11.2 and 12.4 Pa on the brain, and increased with CFR-PEEK 30% and PEEK to 14.1 and 15.5 Pa, and 53.7 and 62 Pa, respectively. Additionally, the contact area between the PEEK implant (whether mesh or plate design) and the left parietal bone of the skull was expected to be damaged due to excessive strains. Importantly, all implants tested did not exceed permissible limits for tensile and compressive stresses and strains on the brain.

It was concluded that carbon fiber-reinforced PEEK implants, with 30% and 60% reinforcements, can be used as alternatives to titanium for cranial reconstruction. The addition of carbon fibers to the PEEK matrix in these percentages enhances the mechanical, chemical, and thermal properties of the implants. Additionally, these composites are characterized by their low weight, biocompatibility, lack of clinical issues, and ease of fabrication. They can also help preserve the skull, protect the brain, and are not susceptible to damage.

Overcoming the drawbacks of titanium cranial implants and increasing the effectiveness of the cranioplasty process by utilizing PEEK and carbon fiber reinforced PEEK materials in the reconstruction of the damaged portion of skull.

This study aimed to investigate the effect of four retention systems for implant-supported posterior crowns under compressive loading using three-dimensional finite element analysis. A morse-taper dental implant (4.1 × 10 mm) was designed with Computer Aided Design software based on non-uniform rational B-spline surfaces. According to International Organization for Standardization 14,801:2016, the implant was positioned at 3 mm above the crestal level. Then four models were designed with different crown retention systems: screw-retained (A), cement-retained (B), lateral-screw-retained (C), and modified lateral-screw-retained (D). The models were imported to the analysis software and mesh was generated based on the coincident nodes between the juxtaposed lines. For the boundary conditions, two loads (600 N) were applied (axial to the implant fixture and oblique at 30°) totaling 8 conditions according to retention design and loading. The von-Mises stress analysis showed that different retention systems modify the stress magnitude in the implant-supported posterior crown. There is a similar stress pattern in the implant threads. However, models C and D presented higher stress concentrations in the crown margin in comparison with A and B. The oblique loading highly increased the stress magnitude for all models. In the simulated conditions, part of the stress was concentrated at the lateral screw under axial loading for model C and oblique loading for model D. The results indicate a possible new failure origin for crown retained using lateral screws in comparison to conventional cement-retained or screw-retained systems.

Three-dimensional (3D) printing technology has advanced for applications in the field of reconstructive surgery. This study reports the application of a comprehensive methodology to obtain an anatomical model, using computed tomography and 3D printing, to treat a patient with cancer who designed a prototype oculopalpebral prosthesis for the reconstruction of the affected area of the face (left eye). A personalized prototype was obtained, which adapted to the face of the person, and improved the aesthetics and quality of life. The applied techniques helped to make definitive prostheses using materials that could be permanent. The training and tests carried out in this study favored the understanding and assimilation of the technology and the possibility of applying it to patients in need of facial prosthetic rehabilitation.

This computational study investigates the effect of the Von Misses stresses and deformations distribution generated by coupling a customized cranial implant with its fixation system for anchoring in the cranial bone of a specific patient. Three simulations were carried out under static loads, in different areas of the implant and during the rest-activity; and another three simulations were considered preset maximum intracranial pressures. Anatomical models were obtained by computed tomography. The design of the device to be implanted was carried out by applying reverse engineering processes, from the corresponding computer-aided design (CAD) model of the bone structure of interest. Likewise, the anchoring system was modeled in detail. Loads were applied at three points on the custom implant. The stress distribution on the artificial plate and the implant-natural bone interface was analyzed. The distribution of the stresses caused by the internal load states on the plate and the anchoring system was also studied. The neurocranial reconstruction with the customized polymethylmethacrylate (PMMA)-based implant and the finite element analysis demonstrated that the fixation and coupling system of the bone-implant interface guarantees adequate protection for the internal structures of the restored area. In addition, the custom-designed and placed implant will not cause non-physiological harm to the patient. Nor will failures occur in the anchoring system.

This article reports on a patient who required a cranial protection system. Using additive manufacturing techniques and surgical planning with the help of bio-models, a patient-specific bone implant solution was proposed that allows aesthetic restoration of the affected area and provides an adequate level of protection. In addition, through a comparative analysis with finite elements, the mechanical response to external actions of the medical device, printed with two materials: polymethylmethacrylate (PMMA) and polyether-ether-ketone (PEEK), is simulated. The tested materials have recognized biocompatibility properties, but their costs on the market differ significantly. The results obtained demonstrate the similarities in the responses of both materials. It offers the possibility that low-income people can access these devices, guaranteeing adequate biomechanical safety, considering that PMMA is a much cheaper material than PEEK.

Three-dimensional (3D) printing, medical imaging, and implant design have all advanced significantly in recent years, and these developments may change how modern craniomaxillofacial surgeons use patient data to create tailored treatments. Polyether-ether-ketone (PEEK) is often seen as an attractive option over metal biomaterials in medical uses, but a solid PEEK implant often leads to poor osseointegration and clinical failure. Therefore, the objective of this study is to demonstrate the quantitative assessment of a custom porous PEEK implant for cranial reconstruction and to evaluate its fitting accuracy. The research proposes an efficient process for designing, fabricating, simulating, and inspecting a customized porous PEEK implant. In this study, a CT scan is utilized in conjunction with a mirrored reconstruction technique to produce a skull implant. In order to foster cell proliferation, the implant is modified into a porous structure. The implant's strength and stability are examined using finite element analysis. Fused filament fabrication (FFF) is utilized to fabricate the porous PEEK implants, and 3D scanning is used to test its fitting accuracy. The results of the biomechanical analysis indicate that the highest stress observed was approximately 61.92 MPa, which is comparatively low when compared with the yield strength and tensile strength of the material. The implant fitting analysis demonstrates that the implant's variance from the normal skull is less than 0.4436 mm, which is rather low given the delicate anatomy of the area. The results of the study demonstrate the implant's endurance while also increasing the patient's cosmetic value.

The current study used polylactic acid molds [developed locally using three-dimensional printers and our software] and polymethyl methacrylate (PMMA) to perform cranioplasty of bone defects in technically demanding areas of the skull while ensuring ideal cosmetic results and functional recovery. The overall aim was to identify the ideal method for standard cranioplasty procedures METHODS: Polylactic acid duplicates of the skull defects were created for eligible patients, after which a two-part negative mold composed of plaster and silicone was used to form artificial bone with PMMA. Thereafter, cranioplasty was performed and the treatment success was assessed by evaluating the percentage of similarity objectively and the body image scale subjectively.

No surgical complications were seen to occur in the 14 patients included in the current study. Furthermore, the subjective and objective evaluation revealed a significant improvement in outcomes (p < 0.05). No postoperative complications were observed over a follow-up period of 6 months, except in 1 patient who exhibited late infection.

Cranioplasty operations were performed at an economical price of approximately US$50 dollars, suggesting that this method can be applied widely. Furthermore, preoperative preparation of the PMMA models can help reduce the duration of anesthesia and surgery which, in turn, will minimize the risk of surgical complications. Based on current knowledge in the field, we believe that this method represents the ideal technique.