The role of the disk in sheep temporomandibular joint ankylosis.

OBJECTIVE: The purpose of this study was to determine the role of the disk in intraarticular ankylosis of the temporomandibular joint. STUDY DESIGN: Twelve adult sheep were divided into 2 groups. In group 1, removal of the temporal and condylar articular surfaces was performed on the right temporomandibular joint and the disk was maintained; in group 2, removal of the articular surfaces and diskectomy were performed on the right temporomandibular joint. One sheep from each group was killed just after surgery and 5 sheep from each group were killed at 3 months. The joints were examined radiologically, macroscopically, and histologically. The range of jaw movements was recorded preoperatively and at sacrifice. RESULTS: Each of 2 sheep in group 2 had lost 4% of their body weight by 3 months; all of the other sheep maintained or increased their weight. The range of jaw motion to the right was significantly lower in group 2 than in group 1 (P<.01). In group 1, fibrous repair of the articular surface and regeneration of the condylar head was seen. In group 2, each of the joints showed a total fibrous ankylosis with some calcification. There was a statistically significant difference in radiologic score between the groups (P<.0001). Histologic scores for group 1 demonstrated significantly lower scores on the degree of ankylosis scale and degree of calcification scale (P<.0001). CONCLUSIONS: This study showed that the presence of the disk prevented the development of fibrous intraarticular ankylosis of the temporomandibular joint.     

翼外肌在创伤性颞下颌关节强直中的作用机制研究

目的 揭示翼外肌在创伤性颞下颌关节（temporomandibular joint, TMJ）强直发病中的作用机制。 方法 本研究纳入6个月大的雄性绵羊8只,双侧髁突均通过手术建立复合创伤继发TMJ强直动物模型,即手术造成双侧髁突矢状骨折、关节盘移位及关节窝损伤。此外,左侧切除部分翼外肌作为实验组,右侧保留翼外肌作为对照组。术后12周,通过用大体观察、螺旋CT扫描、Micro-CT扫描、组织学观察等方法对TMJ样本进行评估与分析。 结果 肉眼观察可见：对照组发生了TMJ骨性强直而实验组仅仅是纤维强直。螺旋CT和Micro-CT结果显示：与实验组相比,对照组关节面粗糙、有新骨形成并突入到关节腔内,且关节腔内有钙化的骨痂形成;对照组髁突的最大内外径和前后径均明显大于实验组（P＜0.05）;Micro-CT扫描结果还显示：对照组新生骨小梁的方向与翼外肌牵拉方向一致,而实验组无此特征。组织学结果也印证了对照组关节内发生了纤维-骨性强直,而实验组仅为纤维强直。 结论 在髁突矢状骨折的愈合过程中,翼外肌发挥了类牵张成骨的作用,从而参与创伤性TMJ强直的发生。     

The role of trauma on temporomandibular joint ankylosis and mandibular growth retardation: an experimental study

The purpose of this pilot study was to analyze the role of different types of trauma in the formation of temporomandibular joint ankylosis. The specific aim was to explore the physical and histological effects of trauma on temporomandibular joint and mandibular growth. Fifty-five growing white male guinea pigs were used for the study. Initially, cadaveric studies were performed (n = 1) to assess the topographic anatomy of the temporomandibular joint region. Animals were then assigned to pilot (n = 4), experimental (n = 40), and control (n = 10) groups. The pilot group was used to assess the technical feasibility of creating various trauma types and endurance of the animals to the surgery. Four types of trauma were carried out in the experimental group: A) intra-articular hematoma (n = 10), B) mechanical damage to the articular surface (n = 10), C) fracture of the condyle neck (n = 10), and D) excision of the condyle head (n = 10). Each trauma group was further divided into two subgroups. Procedures were performed unilaterally or bilaterally in the subgroups. In the control group, no procedure was performed. Subjects were examined after a 2-month follow-up period. The development and anatomical structure of the mandible were evaluated, and histopathological assessment of the temporomandibular joint was carried out in each group. The results revealed that hyaline cartilage of the condylar head had an important role in the development of the mandible and traumas targeting this site may cause ankylosis, growth retardation, and resultant facial malformations. Hence, mechanical damage to the articular surface (B1, B2) and resection of the condylar head (D1, D2) almost always resulted in ankylosis. Intra-articular hematoma alone (A1, A2) was established not be a causative factor for ankylosis formation, however.     

The effect of autogenous costochondral grafts on temporomandibular joint fibrous and bony ankylosis: A preliminary experimental study.

PURPOSE: The purpose of this study was to test the functional and histologic fate of costochondral grafts (CG) in temporomandibular joint (TMJ) reconstruction for unilateral ankylosis in the sheep. MATERIALS AND METHODS: Five pure-bred adult Merino sheep were used. Ankylosis was induced by articular damage, disc removal, and placement of a bone graft. At 3 months, a gap arthroplasty was performed with a CG from the thirteenth rib. The sheep were sacrificed 3 months after CG reconstruction. The range of jaw movements were recorded at first operation, at lysis of ankylosis, and at sacrifice. The joints were examined radiologically, macroscopically, and histologically. RESULTS: All sheep showed a decrease in masticatory function, as shown by weight loss and decreased jaw opening, during the ankylosis period. On release, they regained weight and increased the range of jaw movement. Histologically, the joint space was filled with fibrous tissue. However, the partial spaces around the CG head were covered by fibrous tissue and/or fibrous cartilage. CONCLUSIONS: This study shows that, when CGs are used with a gap arthroplasty in a fibrous and bony ankylosed TMJ, masticatory function is restored.     

Development of temporomandibular joint ankylosis in rats: a preliminary experimental study

The objective of this study was to evaluate a model for the development of temporomandibular joint ankylosis in rats using disc removal and articular damage. In 30 adult male Wistar rats, articular damage was induced and disc removal performed in the right joint to induce ankylosis. The rats were divided into groups according to the time of killing (7, 15, 30, 60 and 90 days). Maximal mouth opening, mandibular deviation, initial and final weights, and duration of surgery were recorded and evaluated. After death, the joints were submitted to histological study in order to score the ankylosis. The mean duration of surgery was 14.23 min. Mean difference between initial and final maximal mouth opening was 3.38 mm, being greatest at the 15-day evaluation and lowest at 90 days, and was statistically significant at 15 days (p=0.043), 30 days (p=0.027) and 60 days (p=0.027). No mandibular deviation was observed at any of the evaluation times. Histological scores increased with time of evaluation from 7 to 30 days, when they started to fall. This study model permitted the development of fibrous ankylosis in the majority of the animals, and no bony bridge was observed between the mandibular condyle and the temporal bone.     

Costochondral grafts in reconstruction of the temporomandibular joint after condylectomy: an experimental study in sheep

The purpose of this study was to investigate the effect of costochondral grafts in the temporomandibular joint (TMJ) in sheep. Five pure-bred adult Merino sheep were used. The condyle alone was resected and replaced with a costochondral graft from the 13th rib. The sheep were killed 3 months after operation. The range of jaw movements before and after operation and at death were recorded. The joints were examined radiologically, macroscopically, and histologically. A new condylar head with normal configuration and function developed. Histologically, the chondrocytes were arranged in a fashion similar to that of a normal joint. All inferior joint spaces showed fibrous adhesions between the condylar head and disc. This study showed that, when such grafts are used to replace the condyle in an otherwise normal sheep TMJ, they fused to the ramus and reconstituted a nearly normal, fully functional joint.     

A sheep model for temporomandibular joint ankylosis.

PURPOSE: The purpose of this study was to develop an animal model for temporomandibular joint (TMJ) ankylosis. MATERIALS AND METHODS: Five sheep had removal of the temporal and condylar articular surface plus discectomy in the right TMJ; the left side was used as a control. One sheep was killed just after operation and four at 3 months. The joints were examined histologically, and a scoring system was developed to evaluate the extent of the ankylosis. The range of jaw movement was compared between preoperatively and 3 months. RESULTS: Two sheep lost 4% of their body weight by 3 months. The range of jaw movement, particularly to the left, decreased at 3 months (P < .001). The joint spaces were filled with fibrous tissue and cartilage-like tissue. Development of new bone from the damaged temporal and condylar surfaces was seen, but full bony fusion did not occur. The average histologic score of a zone was 4.9 on the degree-of-ankylosis scale and 1.7 on the degree-of-calcification scale. There were statistically significant differences between the operated and control TMJs for both changes (P < .0001). CONCLUSION: Fibrous ankylosis occurs rapidly after removal of the TMJ articular surfaces and the disc. This model can be further developed to isolate relative factors in the development of ankylosis and in evaluation of different treatment methods.     

The effect of gap arthroplasty on temporomandibular joint ankylosis: an experimental study.

The aim of this study was to demonstrate the functional and anatomical changes after gap arthroplasty release of unilateral temporomandibular joint (TMJ) ankylosis. Five adult sheep weighing an average of 57 kg were used. All right joints were operated. Ankylosis was induced in the right TMJ by articular damage, disk removal and placement of a bone graft plus immobilization wire. At 3 months the gap arthroplasty were performed. All TMJs were examined functionally, radiologically, macroscopically and histologically. Functionally, the range of jaw movements decreased following induction of ankylosis (P<0.0001), increased immediately on release but was reduced again at 3 months after release (the vertical movement, no statistically significant difference; the right movement, P<0.001; the left movement, P<0.0001). Histologically, all operated joints showed fibrous adhesions across the gap, and further, the articular surface was irregular with osteophytes and with bony islands in the gap. This appearance is more consistent with a fibrous reankylosis than a functioning pseudo joint. This study shows that the gap arthroplasty for TMJ ankylosis did not restore the TMJ functionally and histologically to the preexisting state.     

Induction of traumatic temporomandibular joint ankylosis in growing rats: a preliminary experimental study

Abstract –  There are many reports on the management of pediatric temporomandibular joint (TMJ) ankylosis. However, few authors have investigated the etiology of this disease in children. The purpose of this study was to determine the role of damage to both the condylar cartilage and disk in the induction of traumatic TMJ ankylosis during the growth period. The study was performed in growing rats by a common condyle fracture model. Intentional damage was performed to both the disk and condylar cartilage in the experimental group ( n  = 12), while the disk and condylar cartilage in the control group was left untouched ( n  = 12). Sham-operated growing rats were deemed the blank group ( n  = 10). Two rats from the experimental group and two from the control group were killed 24 h after the operation, and the result following surgical intervention was observed. Each rat's body weight in the three groups was monitored and recorded at 1, 2, 4, 6, 8, 10, and 12 weeks after surgery. Twelve weeks after the operation, all animals were killed. The prognosis was compared by mandible deviation measure, body weight evaluation, and histological observation. Animals from the experimental group presented a slow body weight increase and obvious mandible deviation while all involved TMJs showed fibrous ankylosis in various degrees. The damage to both the condylar cartilage and disk in the condylar fracture might play a vital role in traumatic TMJ ankylosis development during the growth period. The results of this study suggest that more attention should be paid to condylar fractures in children that are accompanied with severe cartilage and disk damage, which is a matter of significance for pediatric TMJ ankylosis prevention.     

A short-term study in sheep with the Groningen temporomandibular joint prosthesis

As part of the pre-clinical testing process of a newly developed temporomandibular joint (TMJ) prosthesis, animal experiments were performed. In 14 sheep, the right TMJ was replaced by the developed TMJ prosthesis. The prosthesis consisted of a skull part, a mandibular part and an intervening polyethylene disc. In the first series (6 sheep), three designs were tested, differing in the applied metal (stainless steel or titanium) and in the fitting method of the skull part (a fitting member or bone cement). The sheep were sacrificed after 8-16 weeks. In the second series (8 sheep), the preferred titanium fitting member design was applied, and the sheep were sacrificed after 2-10 weeks. One sheep was excluded because no correct position of the prosthesis parts could be achieved. At sacrifice, the removal torque of the screws was measured, and the surrounding tissues were harvested for histologic examination. The sheep recovered well and functioned until the end of the scheduled sacrifice date. Encountered problems were two disc dislocations, one fistula formation, and one screw failure. All mandibular parts were clinically stable, as were most skull parts with a fitting member, and one of both skull parts fitted with bone cement. The clinically observed stability was confirmed by the removal torque values, which indicated well-integrated screws. It is concluded that the TMJ prosthesis could remain stable and functional over the initial healing period. The main restriction of the sheep model is the much larger translatory capacity compared with patients, which adversely influences tissue healing.     

创伤性颞下颌关节强直临床分析

目的 分析引发创伤性颞下颌关节(temporomandibular joint,TMJ)强直的高风险髁突骨折类型,初步探讨TMJ强直发生的可能性机制.方法 对18例创伤性TMJ强直进行临床、影像学检查及评估.取纤维性强直外侧变性的关节囊、关节间的致密纤维组织及骨性强直关节外侧骨块和内侧骨块,HE染色,光镜观察.结果 ...     

A clinical study on temporomandibular joint ankylosis in children

Temporomandibular joint (TMJ) ankylosis is a disabling condition of the masticatory system and is most commonly due to trauma, infections, and some systemic diseases. Hypomobility affects the surrounding structures as well as the joint itself. Ankylosis arising in early childhood usually leads to facial asymmetry. Ankylosis in children usually occurs from an intracapsular compression fracture or rarely from a suppurative arthritis of middle ear infection.Treatment of the ankylosis is probably one of the greatest challenges in TMJ surgery, and the treatment of TMJ ankylosis in children is much more challenging than in adults because of high recurrence and the probable change in the unpredictable growth of the mandible. In treatment of TMJ ankylosis in children, to maintain a normal growth and the development of the face is as important as to provide a satisfactory mouth opening with free movement of the mandible.A variety of techniques and various success rates in the treatment of TMJ ankylosis both in adults and in children have been reported. However, no single method has produced uniformly successful results. In this study, gap arthroplasty was applied in 6 patients, and 2 different types of fossa implants were used as interpositional material in the other 8 patients, and the results of the treatments have been evaluated retrospectively.     

Effect of partial immobilization on reconstruction of ankylosis of the temporomandibular joint with an autogenous costochondral graft:an experimental study in sheep

The purpose of this study was to show the effect of partial immobilization of a costochondral graft reconstruction of an ankylosed temporomandibular joint (TMJ) in five adult sheep. Ankylosis was induced in all right TMJs. At three months, a graft was inserted and partially immobilized. Three months after the second operation, four sheep were killed by an overdose with pentothal. One sheep was killed at one month because of infection. Functionally, the body weight, which decreases with ankylosis, did not recover after insertion of the graft and the range of jaw movements got worse. Histologically, the grafts were well attached to the mandibular rami in three of four joints. In one joint, the graft showed signs of resorption and a foreign body reaction. We conclude that, if the reconstructed joint is partially immobilized, then there will be a degree of reankylosis. There was also a high failure rate.     

Silicon in temporomandibular joint ankylosis surgery

Temporomandibular joint ankylosis frequently occurs succeeding untreated or not adequately treated mandible fractures. Treatment of this condition with combined condylectomy and silicon sheet/block application was investigated in the literature. Thirty-eight patients with temporomandibular joint ankylosis were included in this study, and postoperative results were presented. Mean preoperative and postoperative sixth-month interincisor opening values were 5.8 and 28.8 mm, respectively. In two patients (5.2%), another operation to remove silicon material was needed because of infection and exposure of the silicon. One patient (2.6%) was operated on again for limited mouth opening. It was concluded that interpositional arthroplasty with silicon was proved to be a low-cost, easy approach with satisfactory long-term results.     

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.     

Effect of limited jaw motion on ankylosis of the temporomandibular joint in sheep

The purpose of this study was to investigate the effect of limited movement of the jaw on ankylosis of the temporomandibular joint (TMJ). Eighteen adult sheep were divided into two groups. In Group 1, the temporal and condylar articular surfaces were removed together with the disc on the right. In Group 2, we did the same procedures but in addition the jaw movements were limited by a wire. One sheep was killed just after the operation, four at one month, and four at three months, in each group. The range of jaw movements preoperatively and at the time of death were recorded. The joints were examined radiologically, macroscopically, and histologically. We used a scoring system to assess the radiological changes and histological extent of ankylosis. At one month, the joint spaces were filled with fibrous tissue, but a small joint space existed in all four joints in Group 1. In Group 2, there was full ankylosis in two joints and partial ankylosis in two joints. At three months, similar ankylotic changes were seen in both groups. The histological score for ankylosis at one month showed that those in Group 2 were significantly more ankylosed than in Group 1 (P<0.01). The range of jaw movements was more limited at one month in Group 2, both vertically and to the left, and was significantly decreased in both groups (P<0.01) at three months. Limitation of jaw motion hastens the progress of TMJ ankylosis.     

Bony ankylosis of the temporomandibular joint: a computed tomography study

Bony ankylosis of the temporomandibular joint is a disabling disease that almost invariably manifests itself in the first two decades of life. CT of the temporomandibular joints was performed in 50 patients--axial CT in 2 and coronal CT in 48--of whom 43 (86%) had received trauma to the joints. New bone of variable form and thickness was observed in 64 joints (the involvement was bilateral in 14 patients). These joints were classified into one of two categories: type I, medially angulated condyle with deformed articular fossa and a mild-to-moderate amount of new bone formation; and type II, no recognizable condyle or fossa but instead a large mass of new bone. Type I was etiology-specific and seen only when trauma was the antecedent, whereas type II was a sequelae of either insult. A pseudofracture in the new bone was seen in 49 (77%) joints. Six joints showed subtle deformities but no new bone. Since coronal CT fully characterizes the lesion at acceptable radiation exposure levels, it appears to be valuable in the preoperative workup of these patients.     

Surgical correction of temporomandibular joint ankylosis

The correction of temporomandibular joint ankylosis is frequently followed by re-ankylosis, occlusal disturbance and alteration of functional masticatory movements. A multitude of surgical procedures have been devised in an attempt to overcome the complication of re-ankylosis in particular, and to create a functioning pseudoarthrosis where distance between resected bone surfaces and/or interpositional autogenous, homologous or alloplastic material is relied upon to prevent re-ankylosis and facilitate functional joint activity. Success in preventing re-ankylosis is said also to depend on long-term patient compliance in undertaking frequent and usually painful mandibular movement exercises. Achieving a functioning joint often precludes the maintenance of the occlusion and depends on resection of large amounts of bone and the use of alloplastic implants. A surgical technique is presented whereby a minimal gap arthroplasty in the region of the obliterated temporomandibular joint is completed. This minimizes deviation of the mandible to the operated side with the formation of an anterior open bite. Separation of the resected bone surfaces is accomplished using a composite free auricular skin and cartilage graft in order to prevent re-ankylosis as efficaciously as possible, while allowing for the promotion of immediate postoperative mandibular function, continued growth and the construction of a joint similar in broad terms to the pre-existing joint. A two-stage correction of temporomandibular joint ankylosis and concomitant secondary maxillofacial deformity is recommended. The results in 13 patients (17 joints) with a follow-up range of 1.5 to 5.5 years show that in all but one instance (of fibrous re-ankylosis following postoperative joint infection), satisfactory postoperative mandibular function and mouth opening was achieved.