Injured condylar cartilage leads to traumatic temporomandibular joint ankylosis

Clinical course of masticatory function recovery following endoscopic-assisted open reduction and internal fixation in patients with unilateral mandibular condyle fracture

The purpose of this study was to investigate the clinical course of masticatory function recovery following an endoscopic-assisted open reduction and internal fixation (EAORIF) procedure. Patients with a unilateral mandibular condylar fracture who underwent EAORIF for therapeutic purposes were evaluated, with comparisons made between those who underwent the procedure for base or neck fractures. At each time point analyzed after treatment, the occlusal contact area and maximum bite force in patients with a base fracture were greater, although the differences between the groups were not significant. Moreover, at 12 months following EAORIF for a base fracture, occlusal contact area and maximum bite force on the fractured and non-fractured sides were nearly equal, whereas these were significantly reduced in the fractured as compared with the non-fractured side in patients who underwent that treatment for a neck fracture. Additionally, after 12 months in the neck fracture cases, both occlusal contact area and maximum bite force on the fractured side were lower as compared with those on the non-fractured side. These findings indicate that EAORIF is an optimal method for base fracture treatment with regard to masticatory function.

Animal models of temporomandibular joint heterotopic ossification: a scoping review

There are few animal models for heterotopic ossification of the temporomandibular joint (TMJ-HO). This scoping review provides an overview of current knowledge on the induction methods and specific conditions required to produce TMJ-HO in various animal models. Two independent reviewers selected papers from the PubMed, Web of Science, and Cochrane Library databases. The inclusion criteria were articles in English, in vivo studies, and a TMJ-HO induction method. Observational, in vitro, human studies, reviews, and book chapters were excluded. Twenty-four publications were included. HO was surgically, genetically, or chemically induced through single or combined defects in the condyle, articular disc, and temporal bone in animal models (sheep=9 studies, mouse=5, rat=4, rabbit=2, pig=2, goat=1, dog=1, monkey=1) specific for traumatic TMJ-HO (n=4), ankylosis (n=9), osteoarthritis (n=8), experimental disc perforation (n=1), status post-TMJ replacement (n=1), and status post bilateral sagittal split osteotomy (n=1). TMJ-HO remains challenging to study due to its multifactorial etiology and largely unknown pathogenesis, which varies between species. There is a need for more accurate, reproducible animal models that can be extrapolated to human TMJ-HO and a consolidated clinical classification system to allow for meaningful future research.

Ultrasound-guided arthrocentesis for condylar head fracture: a technical report

OBJECTIVES

Double puncture arthrocentesis (DPA) of the temporomandibular joint (TMD) is considered an effective preservative option for managing mandibular condylar head fractures. However, the procedure is commonly performed by a traditional "blind" method using anatomical characteristics. In the present study, an ultrasonography (US) device was applied for the treatment of a case with a fractured mandibular condyle.

METHODS

A 79-year-old female was diagnosed right side condylar head fracture complaining pain of right TMD and reduced mouth opening range: inter-incisor distance of 20 mm. Since the fracture position was high and inoperable, the decision was made to perform DPA of the TMD. The US probe was positioned parallel and slightly oblique to the major axis of the mandibular ramus. Both the posterior and anterior insertions into the joint space were performed according to the axis mentioned above, which enabled the operator to visualize the entirety of the needle.

RESULTS

The device offered safety and ensured accuracy by providing real-time visual aid to the surgeon. The procedure provided an early increase in the inter-incisor distance (31 mm) and pain relief.

CONCLUSIONS

Hence, for the preservative treatment of mandibular condylar head fractures, based on the present study, we recommend US-guided arthrocentesis as a safe, feasible, and effective therapeutic option instead of the conventional "blind" method.

EFFICACY OF ARTHROCENTESIS FOR TREATMENT OF INTERNAL POST-TRAUMATIC TEMPOROMANDIBULAR JOINT DISORDERS

OBJECTIVE

The aim: To study the consequences of temporomandibular joint injury and efficacy of arthrocentesis for treatment of post-traumatic internal temporoman-dibular disorders.

PATIENTS AND METHODS

Materials and methods: 24 patients who experienced trauma history in the head without jaw fractures underwent CT, ultrasound and/or MRI. TMJ ar¬throcentesis was performed according to a modified method of D. Nitzan (1991) under local anesthesia by means of blockade of the peripheral branch of the auricular-temporal nerve on the background of intravenous sedation.

RESULTS

Results: The ages of the patients varied between 18 and 44 years, and mean was 32,58 years. The causes of trauma were diverse, as traffic accident - 3 (12,5%), assault 12 (50%), hit by materials 3 (12, 5%), and fall-down 6 (25%). According to clinical and radiological signs after traumatic temporomandibular disorders, patients were divided into two groups according to Wilkes classification (1989): 13 patients with stage II (early-middle) and 11 - with stage III (middle).The control ultrasound and MRI carried out 3-6 months after arthrocentesis showed no signs of hemarthrosis in 84.61% of patients with intra-articular disorders of the second degree, and in 72.72% of patients with internal disorders of the third degree, the position and function of the articular disc was restored.

CONCLUSION

Conclusions: Arthrocentesis with TMJ lavage is a minimally invasive surgical manipulation that has proven itself in temporomandibular disorders of traumatic origin, in particular after fractures of the articular process of the mandible.

Traumatic temporomandibular joint bony ankylosis in growing rats

BACKGROUND

The pathogenesis of traumatic temporomandibular joint (TMJ) bony ankylosis remains unknown. This study aimed to explore the pathogenesis of traumatic TMJ bony ankylosis in a rat model.

METHODS

Twenty-four 3-week-old male Sprague-Dawley rats were used in this study. Excision of the whole disc, the fibrocartilage damage of the condyle and glenoid fossa, and narrowed joint space were performed in the left TMJ of the operation group to induce TMJ bony ankylosis (experimental side). The right TMJ underwent a sham operation (sham side). The control group did not undergo any operations. At 1, 4, and 8 weeks postoperatively, rats of the operation group were sacrificed and TMJ complexes were evaluated by gross observation, Micro-CT, histological examinations, and immunofluorescence microscopy. Total RNA of TMJ complexes in the operation group were analyzed using RNA-seq.

RESULTS

Gross observations revealed TMJ bony ankylosis on the experimental side. Micro-CT analysis demonstrated that compared to the sham side, the experimental side showed a larger volume of growth, and a considerable calcified bone callus formation in the narrowed joint space and on the rougher articular surfaces. Histological examinations indicated that endochondral ossification was observed on the experimental side, but not on the sham side. RNA-seq analysis and immunofluorescence revealed that Matrix metallopeptidase 13 (MMP13) and Runt-related transcription factor 2 (RUNX2) genes of endochondral ossification were significantly more downregulated on the experimental side than on the sham side. The primary pathways related to endochondral ossification were Parathyroid hormone synthesis, secretion and action, Relaxin signaling pathway, and IL-17 signaling pathway.

CONCLUSIONS

The present study provided an innovative and reliable rat model of TMJ bony ankylosis by compound trauma and narrowed joint space. Furthermore, we demonstrated the downregulation of MMP13 and RUNX2 in the process of endochondral ossification in TMJ bony ankylosis.

Clinical course of masticatory function recovery following arthrocentesis in patients with unilateral mandibular condyle head fracture

The aim of this study was to investigate the clinical course of masticatory function recovery following arthrocentesis. Patients with a unilateral condylar head fracture who underwent arthrocentesis for therapeutic reasons were evaluated and compared with patients with a unilateral condylar head fracture who did not undergo arthrocentesis. At 3 months after treatment, the occlusal contact area and maximum bite force in patients with a fracture treated with arthrocentesis were greater than in those who did not receive arthrocentesis at the same time points, although the differences were not significant. Moreover, at 1 and 3 months following arthrocentesis, mean (±SD) occlusal contact area (1 month: 1.99 ± 0.55 mm², p = 0.01; 3 months: 2.90 ± 1.36 mm², p = 0.03) and maximum bite force (1 month: 82.45 ± 15.04 N, p = 0.01; 3 months: 101.11 ± 14.53 N, p = 0.01) on the fractured side in patients who underwent that treatment were significantly reduced when compared with those on the non-fractured side. The authors conclude that if the priority is to avoid open reduction and internal fixation, then the arthrocentesis approach might be a less invasive alternative, albeit with the price of a prolonged healing interval.

Clinical outcomes of open treatment of old condylar head fractures in adults

The aim of this study was to classify the clinical feasibility and outcomes of open reduction treatment of old condylar head fractures (CHFs). This was a retrospective case series study of patients with old CHFs that were treated with open reduction and internal fixation, with anatomic reduction and sutured fixation of the articular disc. Preoperative and postoperative examinations were recorded and analyzed, including temporomandibular joint (TMJ) symptoms, occlusion, maximum interincisal opening (MIO), and mandibular deviation. Computed tomography (CT) was used to assess condylar morphology and position. Eleven patients with old CHFs were included (nine unilateral and two bilateral). The mean period from condylar fracture to operation was 8.9 months (ranging from 6 to 14 months). The mean follow-up period after surgery was 16.1 months (ranging from 12 to 22 months). At the end of follow-up period, no malocclusion was found, and the MIO had expanded considerably to 37.4 ± 3.8 mm. Postoperative CT showed that all fragments were properly reduced and the condyles were in the normal position. All patients showed apparently improved TMJ function, occlusion, and facial appearance. Our results showed that open reduction treatment could be an effective method for the treatment of old CHFs.

Induction, Treatment, and Prevention of Temporomandibular Joint Ankylosis-A Systematic Review of Comparative Animal Studies

PURPOSE

Several animal models of temporomandibular joint ankylosis (TMJA) have been described for more than the past 2 decades. The aim of this study was 2-fold: 1) to compile and summarize the evidence of animal studies that compare different forms to induce, treat (disease already established), or prevent (after trauma) TMJA; and 2) to address the following focused question: what is the quality of reporting in these studies?

MATERIALS AND METHODS

A systematic review was conducted. Animal studies conducted up to October 2019 comparing at least 2 procedures to induce, treat (disease already established), or prevent (after trauma) TMJA were considered. Compliance with the Animal Research Reporting In Vivo Experiments guidelines was checked for all studies. Studies evaluating treatment of TMJA or preventive measures also were evaluated using the SYstematic Review Center for Laboratory animal Experimentation's risk of bias tool for animal studies.

RESULTS

A total of 24 studies were included. The studies were evaluated for feasibility regarding data synthesis, and a meta-analysis was not suitable because of methodological differences, mainly regarding the animal model chosen and surgical procedures performed to induce TMJA. In 17 articles, authors aimed to investigate different procedures to induce TMJA (fibrous, fibro-osseous, or bony). In 7 articles, different treatment or preventive strategies were compared. The sheep was the most used animal in models of TMJA. Only 25% (6 of 24) of studies reported some step to minimize bias (ie, blinding of investigators, randomization procedures, or allocation concealment). Approximately 54% (13 of 24) of articles clearly commented on study limitations and potential sources of bias. Further animal studies on TMJA should consider improving their reporting standards to increase their validity and improve the reproducibility of animal experiments.

Stimulating Factors and Origins of Precursor Cells in Traumatic Heterotopic Ossification Around the Temporomandibular Joint in Mice

The contributing factors and the origins of precursor cells in traumatic heterotopic ossification around the temporomandibular joint (THO-TMJ), which causes obvious restriction of mouth opening and maxillofacial malformation, remain unclear. In this study, our findings demonstrated that injured chondrocytes in the condylar cartilage, but not osteoblasts in the injured subchondral bone, played definite roles in the development of THO-TMJ in mice. Injured condylar chondrocytes without articular disc reserves might secrete growth factors, such as IGF1 and TGFβ2, that stimulate precursor cells, such as endothelial cells and muscle-derived cells, to differentiate into chondrocytes or osteoblasts and induce THO-TMJ. Preserved articular discs can alleviate the pressure on the injured cartilage and inhibit the development of THO-TMJ by inhibiting the secretion of these growth factors from injured chondrocytes. However, the exact molecular relationships among trauma, the injured condylar cartilage, growth factors such as TGFβ2, and pressure need to be explored in detail in the future.

The effect of celecoxib in traumatic heterotopic ossification around temporomandibular joint in mice

OBJECTIVE

In this study, the role of inflammation in traumatic heterotopic ossification around temporomandibular joint (THO-TMJ), as well as the preventive and treatment effect of celecoxib in THO-TMJ both in vivo and in vitro were explored.

DESIGN

A surgically-induced THO-TMJ mouse model and a co-culture model of ATDC-5 or MC3T3-E1 and RAW-264.7 cells were used in this study for in vivo and in vitro research.

RESULTS

A series of inflammatory factors, such as CD3, CD68, CD20, IL-10, IL-6 and TNF-α, were activated 48 h after trauma in a THO-TMJ model. Local trauma initiated systemic inflammatory responses as well as T cell- and macrophage-mediated local inflammatory responses around TMJ. In addition, expression of COX-2 was significantly elevated. The findings also showed that local injection of celecoxib could effectively alleviate the inflammatory response around TMJ at the early stage of trauma and inhibit the formation of THO-TMJ in vivo. Meanwhile, celecoxib could inhibit chondrogenic differentiation of ATDC-5 and osteogenic differentiation of MC3T3-E1 under inflammatory condition in vitro. Furthermore, celecoxib could inhibit the expression of Bmpr1b in the injured condylar cartilage at the initiation stage of THO-TMJ, which implied that Bmpr1b expressed by the residual condylar cartilage might be related to the pathogenesis of THO-TMJ.

CONCLUSIONS

Inflammation played a crucial role in the pathogenesis of THO-TMJ, and anti-inflammation might be a possible choice to inhibit THO-TMJ, which provided scientific clues for the mechanisms, pharmacotherapy and molecular intervention of THO-TMJ.

In vivo investigation of temporomandibular joint regeneration: development of a mouse model

Temporomandibular joint (TMJ) reconstruction is traditionally invasive. Several investigators have developed animal models, including mouse models, to study the TMJ. However, there are no detailed descriptions of a mouse model to be followed for additional research. The goal of this project was to study minimally invasive TMJ regeneration using tissue engineering in mice. As part of the project, a detailed mouse model was developed, which is described in this article. Eight carcasses were used to study the anatomy of the TMJ of the mouse and 36 mice were used to describe the surgical approach and perioperative management. The study showed similarities and differences when compared to humans. One mouse died suddenly 10 days postoperatively, while 35 mice survived the operation. Keratitis and wound dehiscence were the most common complications. Investigators reviewing this paper should be able to use this mouse model to further study TMJ regeneration in mice.

Removal of the articular fibrous layers with discectomy leads to temporomandibular joint ankylosis

OBJECTIVE

The aim of this study was to investigate whether direct damage of the articular fibrous layers without condylar fracture, combined with discectomy, was enough to induce temporomandibular joint (TMJ) ankylosis.

STUDY DESIGN

Bilateral TMJ surgery was performed in 8 growing sheep. Disk removal (DR) was performed in the lateral two-thirds on the control side, and disk and articular fibrous layers removal (DFLR) was performed in the lateral two-thirds on the experimental side. Four animals were sacrificed for each side at 1 and 3 months postoperatively.

RESULTS

Fibrous ankylosis was achieved on the DFLR side in 2 of 4 sheep and fibro-osseous ankylosis in the other 2 sheep at 1 month after surgery. Fibro-osseous ankylosis developed on the DFLR side in 4 sheep at 3 months postoperatively. On the DR side, pathologic characteristics of TMJ osteoarthritis could be seen; however, no evidence of ankylosis was observed. The scores of TMJ ankylosis for the DR side were significantly lower than those for the DFLR side at different time points (P < .05).

CONCLUSIONS

This study demonstrated that removal of articular fibrous layers combined with discectomy can lead to traumatic TMJ ankylosis.

Preserving the Fibrous Layer of the Mandibular Condyle Reduces the Risk of Ankylosis in a Sheep Model of Intracapsular Condylar Fracture

PURPOSE

The aim of this experimental study was to investigate the role of the fibrous layer of the condylar head in the formation of temporomandibular joint (TMJ) ankylosis in a sheep model of intracapsular condylar fracture.

MATERIALS AND METHODS

Six growing Xiao-wei Han sheep were used in the study, and bilateral TMJ surgery was performed in each sheep. In the left TMJ, sagittal fracture of the condyle, removal of the fibrous layer of the condylar head, excision of two thirds of the disc, and removal of the fibrous zone of the glenoid fossa were performed. In the right TMJ, the same surgical management was performed, except that in each sheep, the fibrous layer of the condylar head was preserved. Three sheep were killed humanely at 1 month postoperatively, and the other 3 sheep were killed humanely at 3 months postoperatively. The TMJ complexes were examined by histologic evaluation.

RESULTS

Fibrous ankylosis was observed on the left side in 3 sheep at 1 month postoperatively and in 2 of 3 sheep at 3 months postoperatively. Fibro-osseous ankylosis was achieved on the left side in 1 sheep at 3 months postoperatively. In the right TMJ, the main postoperative histologic findings included condylar fracture healing, topical rupture or exfoliation of the fibrous layer of the condyle, and fissure between the fibrous layer and the proliferative zone of the condyle. However, no evidence of ankylosis was observed. The TMJ ankylosis scores on the right side were significantly lower than those on the left side at different time points (P < .05).

CONCLUSIONS

This study showed that the presence of the fibrous layer of the condylar head prevented the development of TMJ ankylosis in a sheep model of intracapsular condylar fracture.

Relationship Between Intracapsular Fracture Patterns and Arthroscopic Findings

PURPOSE

To observe the superior joint compartment (SJC) using ultrathin arthroscopy in intracapsular condylar fracture (ICF) of the temporomandibular joint, describe the changes, and evaluate the relations among fracture pattern, arthroscopic findings, and clinical outcome.

PATIENTS AND METHODS

Twenty patients with 27 ICFs were the subject group. Thirteen patients had unilateral ICFs and 7 had bilateral ICF. The fracture patterns were classified into 9 categories, and all patients had arthroscopic examination of the traumatized joint at the time of definitive treatment. At 4 months after treatment of the injury, all patients had a secondary arthroscopy of the ICF joint. In all patients, range of motion (ROM) was measured as the interincisal distance (millimeters) at the first visit to 12 months after the first treatment, and the data were statistically evaluated.

RESULTS

Intra-articular hyperemia, hypervascularity, and temporal bone damage were found, and 4 patients had disc perforations at the first examination. At the second arthroscopy 4 months later, normal healing occurred in 11 joints, all of which had minimally displaced fractures. Fifteen joints showed complete filling of the SJC, all of which had a displaced minor fragment from the fossa. Comparison of the effect of the presence versus absence of SJC fibrosis on ROM showed marked differences from 1 to 12 months. The effect of early versus delayed definitive treatment showed marked differences at 4 and 12 months.

CONCLUSION

The intra-articular condition at 4 months after ICF as observed arthroscopically was related to the minor fragment position. If the minor fragment is nondisplaced, then it will heal to a normal state; however, if the minor fragment is displaced from the fossa, then the SJC shows disc damage and fibrosis. This could lead to fibrous ankylosis.

Traumatic Bony Ankylosis of Temporomandibular Joint as a Complication After Reduction Malarplasty

Reduction malarplasty is one of the most commonly performed cosmetic and plastic surgery in Asian countries. Bony ankylosis of the temporomandibular joint (TMJ) occurs usually as a result of trauma, infection, failed surgeries, and autoimmune diseases. Reduction malarplasty has low incidence of TMJ-related complications. A 33-year-old female patient came with complaint of restricted mouth opening around 18 mm, which was developed immediately after the reduction malarplasty 2 years before. On computed tomography image, bony adhesion and the defect from the surgical drilling were found around right TMJ.The TMJ interpositional gap arthroplasty with temporalis myofascial pedicled flap was done with simultaneous right coronoidectomy. Interincisal opening increased up to 47 mm intraoperatively.

Stereolithographic model-assisted reconstruction of the mandibular condyle with a vascularized fibular flap following hemimandibulectomy: Evaluation of morphological and functional outcomes

The vascularized fibular flap is one of the standard treatment choices for the reconstruction of the mandible; however, the consequences of condylar restoration have not previously been reported. The use of three-dimensional models allows for a more predictable reconstruction. The purpose of the present study was to assess the outcome of stereolithographic model-assisted reconstruction of the mandibular condyle with a vascularized fibular flap. A total of 5 patients underwent mandibular resection including the condyle and immediate reconstruction with a vascularized fibular flap. A stereolithographic model was used to determine the length and angle of the bony reconstruction. In all patients, the temporomandibular joint (TMJ) disc was preserved, and the contoured fibular end was placed directly into the glenoid fossa under the TMJ disc. To investigate the morphological and functional outcomes, radiographic and clinical examinations were performed, and a food scale questionnaire was administered. The mean period of follow-up was 23 months, and all the flaps were viable. Cosmetic results were generally satisfactory. Radiographic assessment revealed that the end of the fibular graft became round-shaped. None of the patients had abnormal bone resorption, dislocation or ankylosis. The mean value of maximum mouth opening was 31 mm. No patients exhibited difficulties with occlusion. All patients recovered their ability to ingest nearly the same foods that were ingested prior to surgery. The stereolithographic model-assisted reconstruction of mandibular condyle with a vascularized fibular flap is therefore useful for morphological and functional reconstructions of the hemimandible, including condylar defects.