Costochondral Graft as Interpositional material for TMJ Ankylosis in Children: A Clinical Study

Analysis of the effect on costochondral graft for TMJ ankylosis with jaw deformities in pediatrics

OBJECTIVES

To evaluate the effects of costochondral grafting (CCG) used for temporomandibular joint ankylosis (TMJA) in growing patients.

MATERIALS AND METHODS

Pediatric patients with TMJA treated by CCG from 2010.5 to 2021.7 were included in the study. CT scans were performed before and after operations with at least 1 year follow-up. The height of the mandibular ramus, menton deviation or retraction, osteotomy gap, etc. were measured by ProPlan CMF1.4 software. CCG growth, resorption, and relapse were evaluated and analyzed with influencing factors such as age, ostectomy gap, etc. by generalized estimating equation.

RESULTS

There were 24 patients (29 joints) with an average age of 6.30 ± 3.13 years in the study. After operation, the mandibular ramus was elongated by 5.97 ± 3.53 mm. Mandibular deviation or retrusion was corrected by 4.82 ± 2.84 mm and 3.76 ± 2.97 mm respectively. After a mean follow-up of 38.91 ± 29.20 months, 58.62% CCG grew (4.18 ± 7.70 mm), 20.69% absorbed (2.23 ± 1.16 mm), and 20.69% re-ankylosed. The re-ankylosis was negatively correlated with the osteotomy gap (OR:0.348,0.172-0.702 95%CI, critical value = 6.10 mm). CCG resorption was positively correlated with the distance of CCG ramus elongation (OR:3.353,1.173-9.586 95%CI, critical value = 7.40 mm).

CONCLUSIONS

An adequate osteotomy gap and CCG ramus elongation distance are the key factors for successful treatment of TMJA with jaw deformities in growing patients.

CLINICAL RELEVANCE

TMJA affects mouth opening and jaw development in pediatric patients. The most common autogenous bone graft for pediatric patients is CCG due to its growth potential, convenient access and easy contouring. Also, it can simultaneously reconstruct the TMJ and improve jaw deformity by lengthening the mandibular ramus. But the growth of CCG is unpredictable. In this study, we explored several factors that may affect the absorption and re-ankylosis of CCG, expecting to provide several suggestions to improve future CCG treatment.

Surgical Treatment of Temporomandibular Joint Ankylosis: our experience with 36 cases

AIM

To evaluate and compare outcomes of patients with temporomandibular joint ankylosis (TMJA) treated by gap arthroplasty, costochondral graft, and total alloplastic joint reconstruction.

METHODOLOGY

A retrospective cohort study reviewed and analyzed data from patients with TMJA from January 1, 2009 to December 31, 2019, at the Maxillofacial and Oral Surgery Department, University of the Witwatersrand. Patients with TMJA were treated either with gap arthroplasty, costochondral graft, or total alloplastic joint reconstruction. Data collected included age, sex, etiology of ankylosis, sides involved, preoperation and postoperation mouth opening (MO), treatment type, complications, and revision surgery. Patients were followed up for at least 18 months after the surgical procedure. Comparison of means across the treatment groups was analyzed using paired t tests or analysis of variance test. A P value of less than 0.05 was considered statistically significant.

RESULTS

The study sample comprised of 36 patients [bilateral, n=22; unilateral, n=14 (21 male, 15 female)]. Trauma was the most common etiology (n=27, 75%), followed by chronic infections (n=4, 11.11%) and juvenile arthritis (n=3, 8.3%). A paired t test revealed no statistical significance between treatment modality and postoperative MO and complications over 18 months (P=0.5316 and P=0.426, respectively). The mean MO increased from 4 to 28 mm. Reankylosis was the most common complication (n=5).

CONCLUSIONS

All 3 treatment options yield acceptable outcomes in patients with TMJA. Irrespective of surgical technique, early postoperative exercises, active physiotherapy, and follow-up are imperative for successful rehabilitation and prevention of reankylosis.

Facial Deformity in an Operated Case of Bilateral Temporomandibular Joint Ankylosis

Temporomandibular joint (TMJ) ankylosis results in malocclusion, poor feeding, difficulty in maintaining oral hygiene, and facial esthetic deformity. The basic surgical objectives in the treatment of TMJ ankylosis are to establish joint movement, prevent relapse, and achieve normal growth and development. Here, we present an operated case ofsurgical correction of mandibular hypoplasia; however, the patient came back after three years due to unsatisfactory results and underwent bilateral coronoidectomy and gap arthroplasty. Bones were osteotomized at the LeFort I level and the maxillary segment was down-fractured and mobilized to bring into occlusion with the mandible. In the present case, the lower pharyngeal airway changed from 5 mm pre-treatment to 10 mm post-treatment, and the facial angle was changed from 73 to 84 post-treatment. Assessment of the pharyngeal airway is done with a high suspicion of obstructive sleep apnea and facial deformity is mandatory in the management of TMJ ankylosis.

Long term complications of costochondral graft reconstruction in temporomandibular joint ankylosis of the young- a systematic review

Costochondral graft has been a popular reconstruction choice in the past for temporomandibular joint ankylosis in young individuals. However, accounts of growth hampering complications have also been observed. Our systematic review aims to compile all existing evidence to determine the occurrence of these unfavourable clinical outcomes as well as factors affecting them to provide a better judgement on further use of these grafts. A systematic review was conducted following PRISMA guidelines where databases like PubMed, Web of science and Google Scholar were searched for the purpose of data extraction. Observational studies performed on patients younger than 18 years of age with a minimum follow-up of one year were selected. Incidence of long term complications like reankylosis, abnormal graft growth, facial asymmetry and others were considered as outcome variables. Eight articles with a total of 95 patients were selected where complications like reankylosis (6.32%), graft overgrowth (13.70%), insufficient graft growth (22.11%), no graft growth (3.20%) and facial asymmetry (20%) were reported. Other complications like mandibular deviation (3.20%), retrognathia (1.05%) and prognathic mandible (3.20%) were also observed. Our review concludes that the occurrence of these complications was noteworthy. Thus use of costochondral graft for reconstruction in temporomandibular ankylosis in young patients holds significant risk in development of growth abnormalities. However, modifications in surgical procedure such as use of appropriate graft cartilage thickness and the presence and type of interpositional material can favourably affect the frequency and type of growth abnormality.

Temporomandibular Joint Ankylosis in a Girl Child: Immunochemical Evaluation of Tissue Material Obtained from Repeated Arthroplasty Surgeries

Temporomandibular joint ankylosis (TMJA) is a rare, but debilitating, condition that leads to TMJ joint hypomobility. Surgery is the mainstay for treatment, which is accompanied by rehabilitative and psychological support. Despite the advances in surgical techniques, the recurrence of TMJA post-surgery has been reported as a common complication. Therefore, it becomes essential to investigate and understand the histo-morpho-pathological processes governing these ankylotic changes. Given the lack of such studies in the literature, herein we present a case of a girl child who underwent primary surgery at the age of six years, followed by a second surgery at the age of twelve years. Ankylotic tissue samples collected during both surgeries were studied using various immunohistochemical markers for tissue remodeling, inflammation, antimicrobial activity, and transcriptional regulation. The expression of MMP-2 and -9 was downregulated in repeated surgery materials, whilst MMP-13 was rarely detected in both tissues. Strong MMP-8, TIMP-2, and TIMP-4 expressions were noted in both tissues, showing their anti-inflammatory and protective roles. Moderately strong expression of bFGF, FGFR-1, IL-1α, and TNF-α could indicate sustained tissue growth in the background of inflammation (wound healing). Interestingly, the expression of β-defensin-2 was found to be constant in both tissues, thereby indicating possible ECM remodeling and collagen breakdown. Finally, a moderate expression of RUNX-2, coupled with a low expression of WNT-1 and -3a, could indicate a slow and delayed bone regeneration process. Our results showcase the complex myriad of pathways that could be involved in the progression of TMJA and post-surgery healing processes. Immunopathological studies could aid in improving the diagnosis, treatment, and prognosis for patients affected with TMJA.

Autogenous grafts for reconstruction arthroplasty in temporomandibular joint ankylosis: A systematic review and meta-analysis

Autogenous methods for reconstruction arthroplasty (RA) for the surgical management of the temporomandibular joint (TMJ) have been extensively reported. The present review was aimed to systematically review and pool data on clinical outcomes of autogenous grafts for RA in subjects with TMJ ankylosis. Major electronic databases and prominent subject-specific journals were searched up to December 2020. Randomised controlled trials (RCT), cohort studies, and retrospective studies reporting outcomes of autogenous grafts for RA in TMJ ankylosis were included. A total of 35 studies with 700 subjects was included. The most commonly employed grafts were costochondral grafts (CCG) and coronoid process grafts. Postoperative change in maximum incisor opening (MIO) was comparable amongst all grafts and was in the clinically acceptable range (27.21-31.38 mm). The recurrence rate was comparable for all grafts and was ≈ 8% except for coronoid grafts, where the recurrence rate was 2.98%. Growth assessment for CCG revealed that 55.89%, 30.89%, and 13.24% of subjects depicted optimal growth, overgrowth, and undergrowth, respectively. Within the limitations of the present review, the recurrence rate for all grafts was comparable except for coronoid graft, which depicted least recurrence rate and resultant postoperative change in MIO was in the clinically acceptable range.

Classification and surgical management of temporomandibular joint ankylosis: a review

The paper reviews various classifications and surgical techniques for the treatment of temporomandibular joint ankylosis. PubMed, EBSCO, Web of Science, and Google Scholar were searched using a combination of keywords. Articles related to classification, resection-reconstruction of the temporomandibular joint, and management of airway obstruction were considered and categorized based on the objectives. Seventy-nine articles were selected, which included randomized clinical trials, non-randomized controlled cohort studies, and case series. Though several classifications exist, most classifications are centered on the radiographic extent of the ankylotic mass and do not include the clinical and functional parameters. Hence there is a need for a comprehensive staging system that takes into consideration the age of the patient, severity of the disease, clinical, functional, and radiographic findings. Staging the disease will help the clinician to adopt a holistic approach in treating these patients. Interpositional arthroplasty (IA) results in better maximal incisal opening compared with gap arthroplasty, with no significant difference in recurrent rates. Distraction osteogenesis (DO) is emerging as a popular technique for the restoration of symmetry and function as well as for relieving airway obstruction. IA, with a costochondral graft, is recommended in growing patients and may be combined with or preceded by DO in cases of severe airway obstruction. Alloplastic total joint replacement combined with fat grafts and simultaneous osteotomy procedures are gaining popularity. A custom-made total joint prosthesis using CAD/CAM can efficiently overcome the shortcomings of stock prostheses.

Growth Outcome and Jaw Functions Are Better After Gap Arthroplasty Plus Costochondral Graft Reconstruction Than Gap Arthroplasty Alone in Pediatric Temporomandibular Joint Ankylosis Patients: A Cluster Randomized Controlled Trial

PURPOSE

It is not known if the muscle matrix that becomes functional after gap arthroplasty (GA) in temporomandibular joint ankylosis (TMJA), induces growth of the mandible or the reconstructive arthroplasty with costochondral graft (CCG) is responsible for growth. The study aimed to evaluate the mandibular growth and functional outcome with the use of CCG/GA in the management of pediatric TMJA.

METHODS

The investigators designed a cluster randomized controlled trial on pediatric (3 to 16 years) TMJA patients. Treatment applied (CCG and GA), was the primary predictor variable. Patients were divided into CCG and GA groups. The primary outcome variable was growth. Secondary outcome variables included etiology and duration of ankylosis, maximal incisal opening (MIO), reankylosis, occlusion, laterotrusion, chin deviation, facial asymmetry, occlusal tilt, and complications. The distance condylion (Co) to gnathion (Gn) was used to measure mandibular length. Ramal height was measured from Co- gonion (Go). Lower facial height was measured from the anterior nasal spine to Gn. Generalized estimating equations were used to calculate the regression coefficient adjusted for the cluster. The patient was considered as a cluster and the unit of analysis was joint.

RESULTS

Fifty-six {n = 28 in each group, (n = 33 joint in the CCG group and n = 31 joints in GA group)} patients were analyzed. The median follow-up was 33-months (31.93 ± 15.24) in CCG and 32-months (32.85 ± 17.84) in the GA group. Intergroup comparison between the CCG and GA group showed a statistically significant difference in mandibular length (CCG = 77.51 ± 9.31 and GA = 66.66 ± 8.32 mm, P < .001), ramal height (CCG = 44.21 ± 7.3 and GA = 31.87 ± 8.4 mm, P < .001), and statistically insignificant difference in lower facial height (CCG = 52.53 ± 6.1 and GA = 50.19 ± 6.3 mm, P = 0.14) at follow-up. Statistically, significant improvement was seen in MIO in both groups (<.001).

CONCLUSIONS

The results of the present study concluded that growth and jaw functions were better in reconstructive arthroplasty with CCG than GA in pediatric TMJA.

Knee orthopedics as a template for the temporomandibular joint

Although the knee joint and temporomandibular joint (TMJ) experience similar incidence of cartilage ailments, the knee orthopedics field has greater funding and more effective end-stage treatment options. Translational research has resulted in the development of tissue-engineered products for knee cartilage repair, but the same is not true for TMJ cartilages. Here, we examine the anatomy and pathology of the joints, compare current treatments and products for cartilage afflictions, and explore ways to accelerate the TMJ field. We examine disparities, such as a 6-fold higher article count and 2,000-fold higher total joint replacement frequency in the knee compared to the TMJ, despite similarities in osteoarthritis incidence. Using knee orthopedics as a template, basic and translational research will drive the development and implementation of clinical products for the TMJ. With more funding opportunities, training programs, and federal guidance, millions of people afflicted with TMJ disorders could benefit from novel, life-changing therapeutics.

Ankylosis management with autogenous grafts: A systematic review

A systematic review was performed to assess the clinical outcomes of the reconstructive methods using autogenous grafts for the management of temporomandibular joint (TMJ) ankylosis A comprehensive electronic and manual search of the literature without date or language restriction was performed in January 2021 to identify randomized controlled trials, prospective, and retrospective studies with the aim of comparing the various surgical modalities for TMJ ankylosis. Twenty-six publications were included: prospective (n ​= ​17), retrospective (n ​= ​7), randomised control trial (n ​= ​1) and ambispective study (n ​= ​1). Costochondral graft was the most common graft used followed by Coronoid process graft. Meta-analysis was not possible as most of studies were non-controlled in nature. Based on the available data, there was a strong evidence that autogenous grafts especially Costochondral grafts and coronoid grafts have remained one of the most favoured methods of reconstruction. Prospective and randomized control studies are recommended for the best stratification for the use of autogenous grafts for the management of TMJ ankylosis.

Management of cardiorespiratory function of rabbits by a customized chest drain: An experimental study

Objective:

This study aimed to salvage the study population from the fatality that occurs due to iatrogenic injury to the thoracic cavity’s pleural membrane.

Materials and Methods:

An experimental study of temporomandibular joint arthroplasty with costochondral graft was carried out on 72 healthy ‘Oryctolagus cuniculus’ species of male rabbits. The rabbits were distributed into two age groups: growing (3–4 months) and adult (12–18 months). All the procedures were carried out under general anesthesia with xylazine hydrochloride and ketamine hydrochloride after calculating the doses, maintained by halothane and O₂ inhalations. Out of 72 rabbits, 33 rabbits had accidental perforation of the pleural membrane observed that required a chest drain.

Results:

In this study, 21 (63.64%) rabbits received chest drain and salvaged. The rest of the rabbits (n = 12; 36.36%) that did not receive any chest drain and died. Most of the rabbits (n = 17; 81%) were under the growing group, weighing less than 2 kg and four (19%) were adult rabbits.

Conclusion:

This manual chest drain is life-saving for rabbits. It is a new addition to the advancement of thoracic surgery on animals. It is cost-effective and safe. The developed customized drainage system may make it easier to harvest the costochondral graft-related experiments.

Can costochondral grafts fulfil ramus-condyle unit reconstruction goals in children with temporomandibular joint ankylosis?

The purpose of this study was to analyse whether costochondral grafts (CCG) fulfil temporomandibular joint (TMJ) reconstructive goals in children with TMJ ankylosis. A total of 23 patients (12 male, 11 female, aged 3-16 years) with unilateral or bilateral TMJ ankylosis operated on between January 2014 to April 2018 were included in the study. Maximal incisal opening (MIO), frequency of reankylosis, and growth of CCG, were evaluated at one month and six months for one year, and after that once yearly. Mouth opening changes with time were assessed by the Friedman test and growth was compared at follow up and analysed using the paired t test. Mean (range) follow up was 18 (12-48) months. Study results revealed follow up MIO at 12 months was highly significant (p=0.001). Out of 27 CCG studied, only one graft had undergone re-ankylosis. Based on the predetermined criteria using condylion to gnathion (Co-Gn) measurement in the posteroanterior cephalogram, CCG were categorised into optimum, sub-optimum, and overgrowth. However, long-standing TMJ ankylosis cases still displayed mandibular asymmetry at the end of the study, even with "optimal growth" radiographically. Overall comparison between the immediate postoperative and last follow up Co-Gn measurements in either unilateral or bilateral cases was not significant. CCG with functional matrix maintained the growth of the mandible and MIO in TMJ ankylosis. It can be concluded that CCG partially fulfils reconstructive goals; however, patients need to be followed up till the end of puberty for a substantive conclusion.

[Long-term effects of autogenous coronoid grafts on the facial growth of children with unilateral temporomandibular joint ankylosis and reconstructed mandibular condyle]

OBJECTIVE

Mandibular condyle injury usually results in malocclusion and disharmony of facial growth in growing children. This study aimed to evaluate the long-term effects of autogenous coronoid grafts on the facial growth of children with unilateral temporomandibular joint (TMJ) ankylosis who underwent mandibular condyle reconstruction.

METHODS

Ten growing patients with unilateral bony TMJ ankylosis admitted in West China Hospital of Stomatology, Sichuan University between January 1st, 2008 and December 31st, 2016 were followed up and evaluated. These patients include three males and seven females with ages ranging from 5 years to 12 years at the time of surgery. Each patient underwent gap arthroplasty, condyle reconstruction with ipsilateral coronoid, and interposition of the pedicled temporalis fascial flap in a single operation. The postoperative follow-up ranged from 3 years to 8 years with an average of 4.9 years. Postoperative panoramic radiographs determined the growth of the mandibular height and length on the affected side and compared it with those of the healthy side.

RESULTS

All patients recovered uneventfully after surgery. At the end of follow-up period, the maximal mouth opening ranged from 32 mm to 41 mm with an average of 35.6 mm. Mandibular height and length continued to grow after the successful treatment of ankylosis using autogenous coronoid grafts for condyle reconstruction. However, growth deficit still existed. The final ramus height and mandibular length of the affected side at the end of follow-up increased by 25.3% (P<0.05) and 26.1% (P<0.05), respectively, compared with the initial values measured immediately after surgery. Growth rates of ramus height and mandibular length of the affected side were 47.1% and 27.2% lower (P<0.05) than those of the healthy side, respectively.

CONCLUSIONS

Mandibular height and length continued to grow after the successful treatment of ankylosis by using autogenous coronoid grafts for condyle reconstruction. However, growth deficit still existed. The growth rate of the affected mandible was reduced compared with that of the undisturbed side even after treatment of ankylosis.

Remaining Hurdles for Tissue-Engineering the Temporomandibular Joint Disc

The temporomandibular joint (TMJ) disc, a fibrocartilaginous structure between the mandible and temporal bone, is implicated in temporomandibular disorders (TMDs). TMDs symptomatically affect approximately 25% of the population, of which 70% have internal derangement of the disc. Treatments lack efficiency, motivating novel therapies, including tissue-engineering toward TMJ disc regeneration. Recent developments in scaffold-based or scaffold-free approaches, cell sources, and biochemical and mechanical stimulation have resulted in constructs exhibiting native tissue mechanics. Safety and efficacy of tissue-engineered implants have shown promising results in orthotopic animal studies. However, many hurdles need to be overcome in tissue-engineering approaches, and clinical and regulatory pathways. Future studies present an opportunity for clinicians and researchers to work together toward safe and effective clinical trials.

Mandibular ascending branch and condyle reconstruction in adolescence by a costochondral rib graft with an observation period over 8 years

Introduction: The need to resect and reconstruct the condylar process of the mandible in a teenager is rare. Reconstruction strategy must be accurately assessed in terms of donor side morbidity, postoperative risks (ankylosis) and the possibility of sufficient development in a growing patient. Observation: A 14-year-old boy presented with the radiographic finding of a large cystic lesion of the right condylar process. There were no clinical symptoms as pain, a limitation of mouth opening or malocclusion. Pathohistological examination confirmed a solitary bony cyst. The resected ascending jaw and condylar process was reconstructed by a costochondral rib graft. Commentaries: Over 8 years the development of the reconstructed ascending jaw and condyle was observed. There was an undisturbed growth. The cartilaginous part of the costochondral graft remodeled to a sufficient condylar process without ankylosis, resorption or overgrowth. Conclusion: The reconstruction of the growing mandible and condylar process in an adolescent is a challenge. Observation over 8 years showed a sufficient reconstruction. Intraoperative the chondral portion of the graft has to be handled carefully to avoid a separating from the bony part. The growth potential of the costochondral rib transplant allows a functional reconstruction without substantial donor side morbidity in adolescent patients.

Tissue Engineering for the Temporomandibular Joint

Tissue engineering potentially offers new treatments for disorders of the temporomandibular joint which frequently afflict patients. Damage or disease in this area adversely affects masticatory function and speaking, reducing patients' quality of life. Effective treatment options for patients suffering from severe temporomandibular joint disorders are in high demand because surgical options are restricted to removal of damaged tissue or complete replacement of the joint with prosthetics. Tissue engineering approaches for the temporomandibular joint are a promising alternative to the limited clinical treatment options. However, tissue engineering is still a developing field and only in its formative years for the temporomandibular joint. This review outlines the anatomical and physiological characteristics of the temporomandibular joint, clinical management of temporomandibular joint disorder, and current perspectives in the tissue engineering approach for the temporomandibular joint disorder. The tissue engineering perspectives have been categorized according to the primary structures of the temporomandibular joint: the disc, the mandibular condyle, and the glenoid fossa. In each section, contemporary approaches in cellularization, growth factor selection, and scaffold fabrication strategies are reviewed in detail along with their achievements and challenges.

Management of facial asymmetry due to overgrowing costochondral graft: A case report

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Costochondral grafts are the gold standard in TMJ replacement in growing patients.

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On occasion, growth in these grafts can sometimes be unpredictable, resulting in facial asymmetry.

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Careful surgical planning is required to ensure that correction of facial asymmetry does not affect the long term function of the temporomandibular joint.

Costochondral grafts are used to replace the mandibular condyle in cases of TMJ ankylosis, and are generally viewed as a gold standard for autogenous reconstruction of the mandibular condyle (Güven, 2000; Posnick and Goldstein, 1993 [1,2]). We report a case where overgrowth of costochondral grafts is seen, resulting in asymmetric mandibular growth and dentofacial asymmetry (Posnick and Goldstein, 1993 [2]).

A 17 year old male patient presented with an existing costochondral graft performed due to TMJ ankylosis during childhood. He fell from a height at the age of 4, and was lost to follow up through non-attendance until the age of 9, when he presented with a progressive reduction in maximal incisal opening (MIO).

At this stage his maximal incisal opening was noted to be 11 mm, and the CT showed a grossly deformed ankylosed left TMJ. This post traumatic ankyloses was managed with gap arthroplasty and costochondral graft reconstruction. This immediately improved his MIO to 22 mm and at 1 year follow up was noted to be 30 mm.

At age 12 he was noted to have a clinically obvious overgrowth of the left ramus of the mandible, and deviation of the chin point to the right. MIO remained at 38 mm.

He declined orthognathic surgery and represented 2 years later requesting treatment without orthodontic intervention for his facial asymmetry. He subsequently underwent a Le Fort 1 impaction osteotomy, right BSSO and left condylar ostectomy, coronoidectomy and left lower border mandibulectomy. Regrowth of the CCG occurred during the 6 months of follow up.

This case illustrates the problems that can occur after condylar trauma. It also highlights issues with costochondral grafts which can continue to grow.

Potential Indications for Tissue Engineering in Temporomandibular Joint Surgery

PURPOSE

Musculoskeletal tissue engineering has advanced to the stage where it has the capability to engineer temporomandibular joint (TMJ) anatomic components. Unfortunately, there is a paucity of literature identifying specific indications for the use of TMJ tissue engineering solutions. The objective of this study was to establish an initial set of indications and contraindications for the use of engineered tissues for replacement of TMJ anatomic components.

FINDINGS

There was consensus among the authors that the management of patients requiring TMJ reconstruction as the result of 1) irreparable condylar trauma, 2) developmental or acquired TMJ pathology in skeletally immature patients, 3) hyperplasia, and 4) documented metal hypersensitivities could be indications for bioengineered condyle and ramus TMJ components. There was consensus that Wilkes stage III internal derangement might be an indication for use of a bioengineered TMJ disc or possibly even a disc-like bioengineered "fossa liner." However, there was some controversy as to whether TMJ arthritic disease (e.g., osteoarthritis) and reconstruction after failed alloplastic devices should be indications. Further research is required to determine whether tissue-engineered TMJ components could be a viable option for such cases. Contraindications for the use of bioengineered TMJ components could include patients with TMJ disorders and multiple failed surgeries, parafunctional oral habits, persistent TMJ infection, TMJ rheumatoid arthritis, and ankylosis unless the underlying pathology can be resolved.

CONCLUSIONS

Biomedical engineers must appreciate the specific indications that might warrant TMJ bioengineered structures, so that they avoid developing technologies in search of problems that might not exist for patients and clinicians. Instead, they should focus on identifying and understanding the problems that need resolution and then tailor technologies to address those specific situations. The aforementioned indications and contraindications are designed to serve as a guide to the next generation of tissue engineers in their strategic development of technologies to address specific clinical issues.