Histological findings in soft tissues around temporomandibular joint prostheses after up to eight years of function

Design and Finite Element Analysis of Patient-Specific Total Temporomandibular Joint Implants

In this manuscript, we discuss our approach to developing novel patient-specific total TMJ prostheses. Our unique patient-fitted designs based on medical images of the patient’s TMJ offer accurate anatomical fit, and better fixation to host bone. Special features of the prostheses have potential to offer improved osseo-integration and durability of the devices. The design process is based on surgeon’s requirements, feedback, and pre-surgical planning to ensure anatomically accurate and clinically viable device design. We use the validated methodology of FE modeling and analysis to evaluate the device design by investigating stress and strain profiles under functional/normal and para-functional/worst-case TMJ loading scenarios.

Does Maximum Voluntary Clenching Force Pose a Risk to Overloading Alloplastic Temporomandibular Joint Replacement?-A Prospective Cohort Study

PURPOSE

The amount of maximum voluntary clenching (MVC) force may influence functional loading at the polyethylene/metal bearing surfaces in alloplastic total temporomandibular joint replacement (TMJR). The aim of this study was to measure ipsilateral MVC and estimate the risk for revision due to overloading of the TMJR.

METHODS

A prospective cohort study design was used to study patients who underwent alloplastic TMJR. The primary predictor was time after TMJR, the secondary predictors were age at TMJR placement, coronoidectomy, prior ipsilateral TMJ surgeries, TMJR design (custom, stock), and bite location. The primary outcome variable was MVC, the secondary outcome was need for TMJR revision. Data were collected preoperatively (T0), and 1 year (T1), 2 to 3 years (T2) and ≥4 years postoperatively (T3). Analysis of variance (ANOVA) with post hoc Tukey-HSD and regression analysis was used for statistical analysis. P < .05 was considered significant.

RESULTS

Thirty-seven patients (58 TMJR) with unilateral (n = 16) and bilateral (n = 21) TMJR were enrolled; 8 males (12 TMJR) and 29 females (46 TMJR). Average age was 46.4 ± 14.9 years. MVC increased significantly over the observation period (P = .000). At all observation time points, age at TMJR placement and bite location significantly influenced MVC (P = .000). Coronoidectomy and prior ipsilateral TMJ surgeries did not demonstrate a significant influence on MVC. TMJR design influenced MVC significantly at T3 (P = .006). Regression analysis identified age as a significant factor for higher MVC. No TMJR required revision or replacement.

CONCLUSIONS

Based on this study, ipsilateral MVC increases significantly after TMJR. However, since MVC is significantly lower than in healthy test-patients, a considerably lower functional loading at the polyethylene/metal bearing surfaces can be assumed. Lower loading at the TMJR bearing surfaces and at the cortical screw fixation sites suggest a potential longer lifespan compared to other artificial joints like hip and knee prostheses.

Synovial entrapment in alloplastic temporomandibular joint replacement

Complications of alloplastic temporomandibular joint (TMJ) prostheses can lead to stress and anxiety for the patient and the surgical team, and prosthesis substitution is sometimes required. The aim of this case report is to describe the surgical finding of synovial entrapment with interposed fibrosis in a postoperative alloplastic TMJ revision, managed effectively with adequate surgical debridement. The authors believe that synovial entrapment needs to be considered as a possible postoperative complication of total joint replacement when no clear symptoms of infection, metal hypersensitivity, osteolysis, or heterotopic bone formation are present. The implications of synovial entrapment in TMJ alloplastic replacement remains relatively unpredictable and poorly understood.

Alloplastic Temporomandibular Joint Replacement in Patients With Systemic Inflammatory Arthritis and Connective Tissue Disorders

PURPOSE

We present a retrospective study to report the outcomes of total temporomandibular joint (TMJ TJR) replacement with alloplastic devices in patients suffering from systemic inflammatory arthropathies.

METHODS

A total of 39 patients with a diagnosis of rheumatoid arthritis (RA), ankylosing spondylitis (AS), psoriatic arthritis (PA), juvenile idiopathic rheumatoid arthritis (JIA), or systemic lupus, underwent alloplastic total joint replacement(s) (TJR) from 1999 to 2019. Maximal interincisal opening (in mm) was recorded before surgery (T0), at 1-year post-surgery (T1) and at last follow-up (T2). A visual analog scale (from 0 to 10) was used for subjective examination of pain before surgery (T0) and at last follow-up (T2). Comparisons were conducted with statistical significance set at P < .05.

RESULTS

Seventy-four joints were replaced in 39 patients. Thirty-two were female. The mean age was 36 years old (range 18-61) and the mean follow-up was 45.9 months (SD 49.4). The most common diagnosis was RA (n = 21), followed by JIA (n = 5) and AS (n = 5), PA (n = 4), lupus (n = 3), and mixed connective tissue disorder (n = 1). The mean pain score had fallen from 6.8 (SD 3.2) at T0 to 1.3 (SD 2.4) (P < .001) at T2. The maximal interincisal opening had improved from a mean of 22.1 mm (SD 13.3) at T0 to 34.3 mm (SD 8.5) (P < .001) at T2. One patient got persistent dysesthesia in the V3 distribution. There were no serious late complications.

CONCLUSION

Patients suffering from systemic inflammatory arthropathies involving the TMJs can be successfully treated by TJR with alloplastic devices. The long-term reduction of TMJ symptoms and functional improvement in this initial study suggest good predictability for this treatment.

Clinical guidelines for total temporomandibular joint replacement

Total joint replacement (TJR) of the temporomandibular joint (TMJ) is a promising surgical procedure and device for treating end-stage diseases of the TMJ. For the functional and aesthetic reconstruction of the oral and maxillofacial head and neck region, TMJ TJR significantly helps maintain the patient's quality of life in terms of a better diet, mastication, speech and social interaction. TMJ TJR was approved by regulatory authorities in 2019 in Japan, thus enabling the clinical application of the TJR system. However, the surgery demands particularly difficult and high-risk procedures, necessitating the prudent selection of indicated patients. The joint committee of the Japanese Society of Oral and Maxillofacial Surgeons and Japanese Society for Temporomandibular Joint is working together to develop an appropriate clinical guideline for TMJ TJR.

Clinical assessment of acellular dermal matrix (AlloDerm©) as an option in the replacement of the temporomandibular joint disc: A pilot study

BACKGROUND

There is limited data available in the literature describing the utility of acellular dermal matrix (AlloDerm©) in the replacement of the temporomandibular joint disc. Few reports of clinicians using implantable AlloDerm to replace the disc do exist, however, this has been described for reconstruction after surgical resection of the entire temporomandibular joint complex to treat pathology, as opposed to isolated articular disc disorders. Moreover, there is a lack of description in the literature regarding associated perioperative outcomes after such a procedure. We sought to assess the immediate perioperative outcomes in the form of a pilot study, to determine whether this technique warrants further investigation in the form of prospective clinical studies.

METHODS

The study team conducted a retrospective review of medical records for patients who underwent temporomandibular joint discectomy and replacement with AlloDerm© at a single tertiary care center, from 2011 to 2016. Perioperative outcomes of interest including pain levels and range of motion were recorded and descriptive statistics were utilized for statistical analysis.

RESULTS

15 patients met the inclusion criteria, of which 87% were females and 13% males. The mean age was 47.27±15.93 years. Preoperatively, 74% of the patients reported severe pain (VAS scores of 7-10); in contrast, 73% of the patients reported only mild pain (VAS scores of 1-3) during the postoperative visits, suggesting an overall reduction in pain intensity. Range of motion also improved from an average of 27.73±13.04mm, to an average of 38.60±6.08mm (P<0.01).

CONCLUSIONS

Based on our preliminary data, patients with advanced TMJ articular disc disorders showed clinical improvement from discectomy and replacement with acellular dermal matrix (AlloDerm©). Further longitudinal studies evaluating long-term outcomes need to be conducted to validate this technique, in the form of larger sample sizes with a control group, as well as radiographic assessment of long-term clinical outcomes.

Prospective study of five-year outcomes and postoperative complications after total temporomandibular joint replacement with two stock prosthetic systems

To evaluate and compare outcomes and complications associated with reconstruction of the temporomandibular joint (TMJ), we prospectively analysed the data of 70 patients who had their joints replaced with stock prostheses during the period 2004-14 and who had been followed up for five years. We used two types of stock prostheses: the metal-on-metal Christensen system (CS), and the ultra-high-molecular-weight-polyethylene-on-metal Biomet® system (BS). Data were collected at 3, 6, 12, 24, 36, 48, and 60 months postoperatively and compared with preoperative measurements. Five years after the replacement there was an increase in mean (SD) mouth opening from 2.0 (0.6) to 4.0 (0.5cm) (p=0.012) in the CS, and from 2.5 (1.0) cm to 4.1 (0.6) cm (p=0.018) in the BS. The mean (SD) reductions in visual analogue pain scores were from 6.9 (1.6) to 2.0 (1.4) (p=0.001) in the CS, and 6.5 (1.4) to 1.5 (1.1) (p=0.001) in the BS. There were no significant differences in improvements in mouth opening or reduction in pain between the two groups. However, there were differences in the number of implants that failed, which led to removal and replacement of 2/14 prostheses in the CS group and 3/77 in the BS group (p=0.06). The results supported the placement of stock prostheses, as evidenced by a low incidence of complications and adverse events, and a long-term improvement in function and reduction in pain in the TMJ. The BS group had significantly fewer prosthetic failures than the CS group.

Advancements in temporomandibular joint total joint replacements (TMJR)

The goal of this paper is to review the advantages and disadvantages of the various treatment options of temporomandibular joint (TMJ) total joint replacement (TJR). TMJ articles published within the last 20 years were reviewed to collect the information on non-invasive and invasive TMD treatment methods. Recent technological advancements helped the evolution of treatment methods and offered significant value to TMD patients and surgeons. Considering the TMD levels, the therapeutic procedures can involve general health examiniations, physical therapy, medication, oral rehabilation or as an end stage clinical invention, temporomandibular joint replacement. In fact when intra-articular TMD is present, the effective treatment method appears to be TJR. However, concern for infection, material hypersensitivity, device longevity and screws loosening issues still exists. Further combined research utilizing the knowledge and expertise of, surgeons, material scientists, and bioengineers is needed for the development of improved TMD therapeutic treatment.

Evaluation of Total Alloplastic Temporomandibular Joint Replacement in TMJ Ankylosis

Introduction

Total joint reconstruction using autologous or alloplastic materials is one of the treatment options for the reconstruction of the affected joint in TMJ ankylosis. The clinical results of alloplastic TM joint replacement (Biomet Microfixation system) that was carried out for the treatment and reconstruction of TMJ ankylosis have been summarised.

Materials and Methods

A retrospective analysis of eight cases clinically and radiographically diagnosed as TMJ ankylosis with minimal facial asymmetry presenting beyond the growth period and willing for at least 12 months of follow-up who have been taken up for gap arthroplasty and reconstruction using Biomet Microfixation TMJ replacement system was carried out. Follow-up of these patients was carried out at regular intervals and assessed on the following criteria: maximal interincisal mouth opening, TM joint pain on the affected side (on VAS), lateral mandibular excursions to the unaffected side deviation on mouth opening, occlusal discrepancy and neuromotor deficit of peripheral branches of facial nerve.

Results

The mean maximal interincisal mouth opening pre-surgery and 1 year post-surgery was 2 and 31.8 mm, respectively. The mean lateral excursive movement to the unaffected side was found to be 5.5 mm with mean deviation on mouth opening to be 4.6 mm. No pain, occlusal discrepancy or neurological deficit existed at the end of 1 year.

Conclusion

Biomet Microfixation system is a viable treatment option for reconstruction of TMJ in cases of ankylosis with no major complications.

Evaluation of total alloplastic temporo-mandibular joint replacement with two different types of prostheses: A three-year prospective study

BACKGROUND

Temporo-Mandibular Joint (TMJ) replacement has been used clinically for years. The objective of this study was to evaluate outcomes achieved in patients with two different categories of TMJ prostheses.

MATERIAL AND METHODS

All patients who had a TMJ replacement (TMJR) implanted during the study period from 2006 through 2012 were included in this 3-year prospective study. All procedures were performed using the Biomet Microfixation TMJ Replacement System, and all involved replacing both the skull base component (glenoid fossa) and the mandibular condyle.

RESULTS

Fifty-seven patients (38 females and 19 males), involving 75 TMJs with severe disease requiring reconstruction (39 unilateral, 18 bilateral) were operated on consecutively, and 68 stock prostheses and 7 custom-made prostheses were implanted. The mean age at surgery was 52.6±11.5 years in the stock group and 51.8±11.7 years in the custom-made group. In the stock group, after three years of TMJR, results showed a reduction in pain intensity from 6.4±1.4 to 1.6±1.2 (p<0.001), and an improvement in jaw opening from 2.7±0.9 cm to 4.2±0.7 cm (p<0.001). In the custom-made group, after three years of TMJR, results showed a reduction in pain intensity from 6.0±1.6 to 2.2±0.4 (p<0.001), and an improvement in jaw opening from 1.5±0.5 cm to 4.3±0.6 cm (p<0.001). No statistically significant differences between two groups were detected.

CONCLUSIONS

The results of this three-year prospective study support the surgical placement of TMJ prostheses (stock prosthetic, and custom-made systems), and show that the approach is efficacious and safe, reduces pain, and improves maximum mouth opening movement, with few complications. As such, TMJR represents a viable technique and a stable long-term solution for cranio-mandibular reconstruction in patients with irreversible end-stage TMJ disease. Comparing stock and custom-made groups, no statistically significant differences were detected with respect to pain intensity reduction and maximum mouth opening improvement.

How Many Temporomandibular Joint Total Joint Alloplastic Implants Will Be Placed in the United States in 2030?

PURPOSE

The purpose of this study is to provide a statistical projection of the number of alloplastic temporomandibular joint (TMJ) total joint replacements (TJRs) that will be performed in the United States through the year 2030.

MATERIALS AND METHODS

The program directors of all 101 Commission on Dental Accreditation-accredited oral and maxillofacial surgery training programs in the United States were surveyed online by use of a questionnaire developed using Redcap (Chicago, IL) over a 6-week period (February 2015-March 2015). The questionnaire included 19 questions related to each program's TMJ disorder and TMJ TJR curricula, as well as clinical experience. In addition, members of the American Society of Temporomandibular Joint Surgeons were surveyed online using Redcap and via direct survey forms. Moreover, requests for the total number of TMJ TJR devices produced and implanted during the same period were made to the 3 manufacturers of Food and Drug Administration-approved TMJ TJR devices in the United States.

RESULTS

The response rate among program directors was 52.5%, and the total number of TMJ TJR devices implanted in oral and maxillofacial surgery programs in 2005 was 412. This total increased by 38% to 572 in 2014. Statistically, this projects an increase of 58% over the next 16 years to 902 TMJ TJR operations by 2030 (95% prediction limits, 768 and 1,037). The total number of TMJ TJR devices distributed by one manufacturer increased from 430 in the year 2000 to 1,004 in 2014 (133%). By use of these data, statistically over the next 16 years, the number of TMJ TJR devices distributed by this company is projected to be 1,658 (95% prediction limits, 1,380 and 1,935).

CONCLUSIONS

The data presented in this study show an increasing demand for the use of TMJ TJR devices in the management of end-stage TMJ disorders to the year 2030.

Experimental and numerical predictions of Biomet(®) alloplastic implant in a cadaveric mandibular ramus

The purpose of this study was to evaluate experimentally the behaviors of an intact and an implanted cadaveric ramus, to compare and analyze load mechanism transfers between two validated finite element models. The intact, clean cadaveric ramus was instrumented with four rosettes and loaded with the temporal reaction load. Next, the Biomet microfixation implant was fixed to the same cadaveric mandibular ramus after resection. The mandibular ramus was reconstructed from computed tomographic images, and two finite element models were developed. The experimental results for the mandibular ramus present a linear behavior of up to 300 N load in the condyle, with the Biomet implant influencing strain distribution; the maximum influence was near the implant (rosette #4) and approximately 59%. The experimental and numerical results present a good correlation, with the best correlation in the intact ramus condition, where R(2) reaches 0.935 and the slope of the regression line is 1.045. The numerical results show that screw #1 is the most critical, with maximum principal strains in the bone around 21,000 με, indicating possible bone fatigue and fracture. The experimental results show that the Biomet temporomandibular joint mandibular ramus implant changes the load transfer in the ramus, compared to the intact ramus, with its strain-shielding effect. The numerical results demonstrate that only three screws are important for the Biomet TMJ fixation. These results indicate that including two proximal screws should reduce stresses in the first screws and strains in the bone.

Two-year prospective study of outcomes following total temporomandibular joint replacement

The purpose of this 2-year prospective study was to investigate outcomes achieved with a stock temporomandibular joint (TMJ) replacement system in the management of end-stage TMJ disorders. Fifty-two patients requiring reconstruction (36 unilateral/16 bilateral) were operated on during the period 2006-2012; 68 total prostheses were implanted (Biomet Microfixation TMJ Replacement System). The mean age at surgery was 52.6±11.5 years. Changes in the values of inclusion diagnostic criteria at entry were assessed. These included persistent and significant TMJ pain, functional impairment after failure of other surgical therapies, and imaging evidence consistent with advanced TMJ disease of more than 1-year duration. Subjects were excluded if they presented insufficient quantity/quality of bone to support the TMJ replacement, severe hyperfunctional habits, active infectious disease, or an inability to follow postoperative instructions. Over the 2 years of postoperative follow-up, mean pain intensity was reduced from 6.4±1.4 to 1.6±1.2 (P<0.001), and jaw opening was improved from 2.7±0.9cm to 4.2±0.7cm (P<0.001). During the study period, three of 68 implants (4%) were explanted and new TMJ replacements fitted. The results of this study support the view that the surgical placement of stock TMJ prostheses provides significant long-term improvements in pain and function, with few complications.

Alloplastic total temporomandibular joint replacement using stock prosthesis: a one-year follow-up report of two cases

Alloplastic total replacement of the temporomandibular joint (TMJ) was developed in recent decades. In some conditions, previous studies suggested the rationale behind alloplastic TMJ replacement rather than reconstruction with autogenous grafts. Currently, three prosthetic products are available and approved by the US Food and Drug Administration. Among these products, customized prostheses are manufactured, via computer aided design/computer aided manufacturing (CAD/CAM) system for customized design; stock-type prostheses are provided in various sizes and shapes. In this report, two patients (a 50-year-old female who had undergone condylectomy for the treatment of osteochondroma extending to the cranial base on the left condyle, and a 21-year-old male diagnosed with left temporomandibular ankylosis) were treated using the alloplastic total replacement of TMJ using stock prosthesis. The follow-up results of a favorable one-year, short-term therapeutic outcome were obtained for the alloplastic total TMJ replacement using a stock-type prosthesis.

Alloplastic or autogenous reconstruction of the TMJ

Reconstruction of the irreparably damaged temporomandibular joint (TMJ) is dependent on the cause of damage and the patient's age. In childhood the current preference is for autogenous reconstruction which can potentially "grow" with the child. This is either with soft tissue interposition (temporalis fascial interposition), local osteotomy, distraction osteogenesis, non-vascularised tissue (costochondral, sternoclavicular) or vascularised tissue (second metatarsal). Current debate centres around the possibility of alloplastic reconstruction particularly where autogenous tissue has failed. The resultant failure of growth - if this occurs, can be dealt with in late adolescence with either osteotomy, distraction osteogenesis or replacement of the condylar component of the prosthesis. In the adult the choice is currently in favour of alloplastic reconstruction as this gives a more stable long term result and facilitates early mobilisation. Initial cost is clearly an issue, but when weighted against the reduced length of stay and reduced morbidity, often the costs are equivalent in the short term and come to benefit alloplasts in the medium term. Their long term outcomes beyond 15 years are however not clear.

Anti-fibrosis effect of BMP-7 peptide functionalization on cobalt chromium alloy

Orthopedic metallic prosthetic implants are commonly made of cobalt chromium (CoCr) alloys. However, such metal-based implants are susceptible to fibrous capsule formation on the implant surface after implantation. At the bone-implant interface, this capsule can prevent implant integration, resulting in loosening and failure. Minimizing the development of such a capsule on the CoCr surface would improve direct bone-implant bonding leading to long-term implant functionality. We evaluated the anti-fibrosis effect of bone morphogenic protein-7 (BMP-7) peptide covalently bonded to CoCr alloy. This peptide, a biomimetic derivation of the knuckle epitope of BMP-7, was conjugated at the N-terminus with a cysteine amino acid. X-ray photoelectron spectroscopy (XPS) and probe binding assay were used to evaluate different stages of grafting and surface functionalization using polydopamine coating. Cellular functions were studied using fibroblast attachment, cell proliferation, and MTT assays. Fibroblasts were grown on functionalized and pristine CoCr substrates, and the efficacy of BMP-7 peptide on anti-fibrosis was analyzed via gene expression and protein expression of fibrosis markers ACTA2, Collagen 1A1, and fibronectin. The peptide functionalized substrates showed significant reduction of fibrosis markers expression after 1 week of incubation compared to controls. BMP-7 signaling pathway activation was shown by the presence of phosphorylation of Smad1/5/8. These findings may contribute to the improvement of CoCr implants in orthopedic surgery applications.