Advancements in temporomandibular joint total joint replacements (TMJR)

Viable Vitreous Grafts of Whole Porcine Menisci for Transplant in the Knee and Temporomandibular Joints

The shortage of suitable donor meniscus grafts from the knee and temporomandibular joint (TMJ) impedes treatments for millions of patients. Vitrification offers a promising solution by transitioning these tissues into a vitreous state at cryogenic temperatures, protecting them from ice crystal damage using high concentrations of cryoprotectant agents (CPAs). However, vitrification's success is hindered for larger tissues (>3 mL) due to challenges in CPA penetration. Dense avascular meniscus tissues require extended CPA exposure for adequate penetration; however, prolonged exposure becomes cytotoxic. Balancing penetration and reducing cell toxicity is required. To overcome this hurdle, a simulation-based optimization approach is developed by combining computational modeling with microcomputed tomography (µCT) imaging to predict 3D CPA distributions within tissues over time accurately. This approach minimizes CPA exposure time, resulting in 85% viability in 4-mL meniscal specimens, 70% in 10-mL whole knee menisci, and 85% in 15-mL whole TMJ menisci (i.e., TMJ disc) post-vitrification, outperforming slow-freezing methods (20%-40%), in a pig model. The extracellular matrix (ECM) structure and biomechanical strength of vitreous tissues remain largely intact. Vitreous meniscus grafts demonstrate clinical-level viability (≥70%), closely resembling the material properties of native tissues, with long-term availability for transplantation. The enhanced vitrification technology opens new possibilities for other avascular grafts.

Computational modelling of the fossa component fixation associated with alloplastic total temporomandibular joint replacements

The alloplastic total temporomandibular joint (TMJ) replacement is a complex surgical approach to end-stage TMJ disorders. The fixation of TMJ prostheses remains a critical issue for implant design and performance. For the fossa component, it is generally considered to use fixation screws to achieve tripod stability. However, the fossa may still come loose, and the mechanism remains unknown. A computational framework, consisting of a musculoskeletal model for calculating muscle and TMJ forces, and a finite element model for the fossa fixation simulation, was developed. A polyethylene (PE) fossa with stock prosthesis design was analyzed to predict contact pressures at the fixation interfaces, and stresses/strains in the fossa implant and bone during the static loading of normal chewing bite and maximum-force bite. The predicted maximum von Mises stresses were 33 MPa and 44 MPa for the bone, 13 MPa and 28 MPa for the PE fossa, and 131 MPa and 244 MPa for the screws, for the normal and maximum bites, respectively; the peak minimum principal strain was in the range of -2514 ∼ -3545 με for the bone. The results show that the sufficient initial mechanical strength of the fossa component fixation can be established using the screws in combination with bone support. The functional loads applied through the prosthetic TMJ bearing can be largely transferred to supporting bone without causing high level stresses. Tightening fixation screws with a pretension of 100 N can reduce transverse load to the screws and help prevent screw loosening. Further research is recommended to accurately quantify the transverse load and its influence on screw loosening during dynamic loading, and the frictional properties at the bone-implant interface.

Extended total temporomandibular joint reconstruction prosthesis: A comprehensive analysis

Alloplastic total temporomandibular joint replacement (TMJR) is the treatment of choice for end-stage temporomandibular joint diseases. Extended TMJR (eTMJR) is a modification of the standard alloplastic fossa-condyle joint that includes components extending further to the skull base or the mandible. The aim of this study is to review the use of the eTMJR prosthesis for the treatment of large craniomaxillofacial defects. Data mining was performed according to the PRISMA statement using online search in databases such as PubMed (Medline), Google Scholar, Dimensions, Semantic Scholar and Web of Science. A total of 19 case reports, 08 case series and 03 retrospective studies were identified. A total of 49 patients were presented in the case reports and case series, who were implanted with 56 eTMJR prostheses (07 bilateral and 42 unilateral procedures). The mean age of the patients was 36.02±16.54 years, the male to female patient ratio was 1:1.72 and the mean follow-up time was 23.74 ± 19.83 months. The eTMJR prosthesis was most frequently used to treat ameloblastoma and hemifacial microsomia. Analysis of the retrospective studies was performed in three domains: the baseline characteristic of patients, treatment outcomes in terms of functional variables and complications after eTMJR prostheses implantation. This study concluded that the implantion of the eTMJR prosthesis was uncommon, that appropriate class of eTMJR prosthesis was not reported, and that the width of the mandibular component (like the length) of eTMJR prosthesis has substantial variations.

Do Case Reports on Total Mandibular, Extended, and Bilateral Total Temporomandibular Joint Reconstruction Prostheses Adhere to the Surgical CAse REport Guidelines?

PURPOSE

The Surgical CAse REport (SCARE) guidelines are a standardized format for reporting surgical cases. The aim of this study was to evaluate the completeness of case reports documenting alloplastic reconstruction of large craniomaxillofacial defects involving total mandibular, bilateral, and extended temporomandibular joint in major high-quality craniomaxillofacial journals, based on the SCARE guidelines.

METHODS

An extensive online search was performed according to the Priority Reporting Items for Systematic Reviews and Meta-Analyses statement in PubMed, Embase, Scopus, Google Scholar, and Dimensions databases to identify relevant case reports. Each selected case report was assessed on 16 topics (38 items) of the SCARE guidelines, using a scoring scale of "0" (No/noncompliance), "1" (Yes/compliance), and 2" (unclear). The completeness of reporting (COR) score was calculated as the ratio of "yes" responses to "total" (ie, yes + no + unclear) responses. Adequacy of case reporting was denoted by a COR score of 70% or more.

RESULTS

A total of 35 case reports were selected, where the male to female patients ratio was 3:4 cases, mean ± standard deviation (SD) age: 34.9 ± 16.7 years, mean ± SD follow-up duration: 17.0 ± 12.9 months, and number of patients with left, right, and bilateral temporomandibular joint reconstruction prostheses were 16, 10, and 09, respectively. The mean ± SD COR score for all 35 case reports and the individual item of the SCARE guidelines was 70.2 ± 10.5% and 66.5 ± 31.2%, respectively. The minimum and maximum COR score was found for "Keywords" (0.0%) and "Introduction" (100%) and "Clinical Findings" (100%), respectively. Adequate reporting was found for 20/35 (57%) case reports.

CONCLUSIONS

This study revealed that case reports in major high-quality craniomaxillofacial journals suffer from insufficient reporting. Widespread adoption of available standards, such as SCARE guidelines, is proposed to improve the quality and robustness of case reporting.

Complications of total temporomandibular joint replacement: a systematic review and meta-analysis

The aim of this systematic review was to determine the most prevalent complications resulting from total temporomandibular joint (TMJ) replacement. An electronic search was performed using the Embase, LILACS, MEDLINE (via PubMed), SciELO, Scopus, and Web of Science databases up to June 2022. Prospective and retrospective clinical studies on patients who underwent TMJ replacement were included. Two reviewers performed the study selection, data extraction, and individual risk of bias assessment using the Joanna Briggs Institute Critical Appraisal Tools. The pooled prevalence of each complication was calculated through a proportion meta-analysis using the random-effects model. Twenty-eight studies met the eligibility criteria and were included in the review. All of the eligible studies had a low risk of bias. The results of the meta-analysis revealed that the most prevalent complication was paresis or paralysis of the facial nerve branches (7.8%; 95% confidence interval (CI) 2.6-15.1%, I2 = 94.5%), followed by sensory alterations (1.8%; 95% CI 0.6-4.9%, I2 = 88.8%), heterotopic bone formation (1.0%; 95% CI 0.1-2.5%, I2 = 75.8%), and infection (0.7%; 95% CI 0.1-1.6%, I2 = 22.7%). In conclusion, TMJ replacement has a low prevalence of complications, and most of them can be managed successfully.

Puricelli biconvex arthroplasty as an alternative for temporomandibular joint reconstruction: description of the technique and long-term case report

Background

There are several indications for partial or total replacement of the temporomandibular joint (TMJ), including neoplasms and severe bone resorptions. In this regard, several techniques have been suggested to increase the functionality and longevity of these prosthetic devices. This case report describes the treatment of a TMJ ankylosis patient with the Puricelli biconvex arthroplasty (ABiP) technique, with a long-term follow-up.

Case presentation

In 1978, a 33-year-old male polytraumatised patient developed painful symptoms in the right preauricular region, associated with restricted movement of the ipsilateral TMJ. Due to subcondylar fracture, an elastic maxillomandibular immobilisation (EMMI) was applied. Subsequently, the patient was referred for treatment when limitations of the interincisal opening (10 mm) and the presence of spontaneous pain that increased on palpation were confirmed. Imaging exams confirmed the fracture, with anteromedial displacement and bony ankylosis of the joint. Exeresis of the compromised tissues and their replacement through ABiP was indicated. The method uses conservative access (i.e., preauricular incision), partial resection of the ankylosed mass, and tissue replacement using two poly(methyl methacrylate) components, with minimal and stable contact between the convex surfaces. At the end of the procedure, joint stability and dental occlusion were tested. The patient showed significant improvement at the postoperative 6-month follow-up, with no pain and increased mouth opening range (30 mm). At the 43-year follow-up, no joint noises, pain or movement restrictions were reported (mouth opening of 36 mm). Imaging exams did not indicate tissue degeneration and showed the integrity of prosthetic components.

Conclusions

The present case report indicates that ABiP enables joint movements of the TMJ, allowing the remission of signs and symptoms over more than 40 years of follow-up. These data suggest that this technique is a simple and effective alternative when there is an indication for TMJ reconstruction in adult patients with ankylosis.

Patient specific total temporomandibular joint reconstruction: A review of biomaterial, designs, fabrication and outcomes

Purpose

The aim of this article was to systematically review the available literature on patient specific total temporomandibular joint total joint replacement (PS-TMJR) implants for their biomaterial, designs, fabrication techniques and their outcomes.

Methods

A literature review was conducted using PubMed, and science direct databases using the key words three-dimensional printing, 3D printing, CAD CAM, computer aided designing, computer aided manufacturing, additive technology, custom made implants, patient specific implants in combination with Temporomandibular joint, TMJ surgery.

Results

The search revealed 2760 articles, of which 374 were in English and discussed TMJ reconstruction. Further filtering shortlisted 74 articles that discussed PS-TMJR. Duplicates were removed and additional added from article references. 39 articles describing biomaterial, designing and fabrication of PS-TMJR implants and their outcomes were selected for analysis.

Conclusions

Although PS-TMJR implants allow a better anatomical fit, improved fixation, and safeguard various structures such as the inferior alveolar nerve, they vary in designs, material and fabrication techniques. However, PS-TMJR printed with SLM and EBM technologies have yet to be compared with the conventional ones in terms of mechanical strength, and clinical outcome. With emerging bioprinting technologies, even newer biomaterials should be considered for 3D printing of PS-TMJR devices designed to achieve harmony in function between the joint device, bone and masticatory muscles.

Preparation, characterization, and feasibility study of Sr/Zn-doped CPP/GNS/UHMWPE composites as an artificial joint component with enhanced hardness, impact strength, tribological and biological performance

In order to solve the problem of aseptic loosening of artificial joints resulting from the wear particles of artificial joint components in total joint replacement (TJR), we synthesized a new kind of metalo-organic particle (Sr/Zn-doped CPP/GNS) using spark plasma sintering (SPS) as a filler to enhance the comprehensive performance of UHMWPE. Sr/Zn-doped CPP/GNS was interfused evenly with UHMWPE particles and cured in a hot press instrument to prepare Sr/Zn-doped CPP/GNS/UHMWPE composites. FTIR and SEM were carried out to characterize Sr/Zn-doped CPP/GNS particles. EDS was carried out to characterize Sr/Zn-doped CPP/GNS/UHMWPE. The micro-structure, hardness, impact strength, tribology and bio-activities of Sr/Zn-doped CPP/GNS/UHMWPE composite materials were also investigated. The results confirmed the effectiveness of this method. The hardness, impact strength, and tribology of the composites were enhanced by adding homodispersed Sr/Zn-doped CPP/GNS particles into UHMWPE. In the meantime, Sr/Zn-doped CPP/GNS/UHMWPE composites could significantly promote the growth of osteoblasts due to the bio-activity of Sr/Zn-doped CPP/GNS. Furthermore, the addition of Sr/Zn-doped CPP/GNS particle-fillers into UHMWPE could promote the secretion of OPG from osteoblasts and inhibit the secretion of RANKL from osteoblasts, and thus increase the OPG/RANKL ratio. All the results above showed that Sr/Zn-doped CPP/GNS/UHMWPE composites with appropriate Sr/Zn-doped CPP/GNS content possessed superior physicochemical performances and bio-properties, and could be considered as promising materials to treat aseptic loosening in total joint replacement.

A new kind of metalo-organic particle (Sr/Zn-doped CPP/GNS), synthesized using spark plasma sintering (SPS), was used as a filler to enhance the comprehensive performance of UHMWPE for applications in joint replacement.

Development of 3D-printed myoelectric hand orthosis for patients with spinal cord injury

BACKGROUND

Spinal cord injury (SCI) is a severe medical condition affecting the hand and locomotor function. New medical technologies, including various wearable devices, as well as rehabilitation treatments are being developed to enhance hand function in patients with SCI. As three-dimensional (3D) printing has the advantage of being able to produce low-cost personalized devices, there is a growing appeal to apply this technology to rehabilitation equipment in conjunction with scientific advances. In this study, we proposed a novel 3D-printed hand orthosis that is controlled by electromyography (EMG) signals. The orthosis was designed to aid the grasping function for patients with cervical SCI. We applied this hand exoskeleton system to individuals with tetraplegia due to SCI and validated its effectiveness.

METHODS

The 3D architecture of the device was designed using computer-aided design software and printed with a polylactic acid filament. The dynamic hand orthosis enhanced the tenodesis grip to provide sufficient grasping function. The root mean square of the EMG signal was used as the input for controlling the device. Ten subjects with hand weakness due to chronic cervical SCI were enrolled in this study, and their hand function was assessed before and after wearing the orthosis. The Toronto Rehabilitation Institute Hand Function Test (TRI-HFT) was used as the primary outcome measure. Furthermore, improvements in functional independence in daily living and device usability were evaluated.

RESULTS

The newly developed orthosis improved hand function of subjects, as determined using the TRI-HFT (p < 0.05). Furthermore, participants obtained immediate functionality on eating after wearing the orthosis. Moreover, most participants were satisfied with the device as determined by the usability test. There were no side effects associated with the experiment.

CONCLUSIONS

The 3D-printed myoelectric hand orthosis was intuitive, easy to use, and showed positive effects in its ability to handle objects encountered in daily life. This study proved that combining simple EMG-based control strategies and 3D printing techniques was feasible and promising in rehabilitation engineering.

TRIAL REGISTRATION

Clinical Research Information Service (CRiS), Republic of Korea. KCT0003995. Registered 2 May 2019 - Retrospectively registered.