Changes in temporomandibular joint spaces after arthroscopic disc repositioning: a self-control study.

Disc repositioning is a common procedure for patients with anterior disc displacement (ADD). The purpose of this retrospective record-based study was to evaluate changes in the widths of joint spaces and condylar position changes in patients with unilateral ADD following arthroscopic disc repositioning, with the healthy sides as self-control, using magnetic resonance images (MRI).Widths of anterior, superior, and posterior joint spaces (AS, SS, and PS) were measured. The condylar position was described as anterior, centric or posterior, expressed as . Paired-t test and Chi-square test were used to analyze the data. Fifty-four records conformed to the inclusion criteria (mean age of 21.02 years). Widths of SS and PS increased significantly after surgery (P < 0.001) on the operative sides, while joint spaces of healthy sides and AS of operative sides had no significant changes. Dominant location of condyles of operative sides changed from a posterior position to an anterior position, while healthy sides were mostly centric condylar position no matter preoperatively or postoperatively. Therefore, the results of this study indicate that unilateral arthroscopic disc repositioning significantly increases the posterior and superior spaces of the affected joints, without affecting spaces of the healthy sides.

Does condylar height decrease more in temporomandibular joint nonreducing disc displacement than reducing disc displacement?: A magnetic resonance imaging retrospective study.

The aim of the study was to compare condylar height changes of anterior disc displacement with reduction (ADDwR) and anterior disc displacement without reduction (ADDwoR) in temporomandibular joint (TMJ) quantitatively, to get a better understanding of the changes in condylar height of patients with anterior disc displacement who had received no treatment, and to provide useful information for treatment protocol. This longitudinal retrospective study enrolled 206 joints in 156 patients, which were divided into ADDWR group and ADDwoR group based on magnetic resonance imaging examination. The joints were assessed quantitatively for condylar height at initial and follow-up visits. Also, both groups were further divided into 3 subgroups according to age: <15 years group, 15 to 21 years group, and 22 to 35 years group. Paired t test and independent t test were used to assess intra- and intergroup differences. The average age of the ADDwR group was 19.65 years with a mean of 9.47 months' follow-up. The follow-up interval of the patients with ADDwoR was 7.96 months, with a mean age of 18.51 years. Condylar height in ADDwoR tended to decrease more than those in ADDwR, especially during the pubertal growth spurt and with the presence of osteoarthrosis, meaning ADDwoR could cause a severe disturbance in mandibular development. Thus, an early disc repositioning was suggested to avoid decrease in condylar height.

Pigmented villonodular synovitis of the temporomandibular joint with intracranial extension.

Pigmented villonodular synovitis is an uncommon benign tumor-like proliferative lesion with an undetermined origin. Involvement of the temporomandibular joint is uncommon. Although pigmented villonodular synovitis is a benign lesion, it can grow with an aggressive pattern, and it extends extra-articularly in most of the reported cases, about one-third of them exhibiting intracranial involvement. The authors reported an additional case of a 47-year-old woman with intracranial extension, who had a history of joint pain and trismus. The preoperative diagnosis was made with arthroscopy. The lesion was completely excised via preauricular approach and condylotomy. The bone defect was covered by the pedicled temporalis myofascial fat flap. The patient has been symptom-free for 40 months postoperatively.

Magnetic resonance imaging applied to the diagnosis of perforation of the temporomandibular joint.

OBJECTIVE: To investigate the diagnostic accuracy of magnetic resonance imaging (MRI) for perforation of temporomandibular joint (TMJ). METHODS: Consecutive 1845 patients (2524 joints) diagnosed as internal derangement (ID) of TMJ were collected from April 2003 to March 2010 in our department. All the patients were examined by MRI and treated by arthroscopy or open surgeries. The findings of interpreting MRI were recorded as positive, suspicious and negative according to the MRI radiographic criteria. After comparing the findings of MRI with those of arthroscopy or open surgeries, the numbers of true positive, true negative, false positive and false negative were obtained. Through SPSS16.0, receiver operator characteristic curve (ROC curve) was made with 1-specificity as abscissa and the sensitivity as ordinate, and the area under the ROC curve was calculated. According to the area, the diagnostic value of MRI was evaluated. RESULTS: Arthroscopic or open surgeries findings confirmed that 207 joints had disc perforation among all joints. MRI findings showed 189 joints were positive, 197 joints suspicious, and 2138 joints negative. The true positive accuracy of MRI findings was 102/189 while true negative accuracy was 2075/2138. 42 of the 197 suspicious joints had perforation. The area under the ROC curve was 0.808 (0.77, 0.85), P < 0.05. CONCLUSION: We concluded that MRI proved to be a good modality to diagnose disc perforation of TMJ, and the diagnostic result of disc perforation by MRI had certain guiding significance in our clinical work.

Can puncture increase the risk of intra-articular adhesion in the temporomandibular joint?

PURPOSE: This study aims to compare the incidence and severity of intra-articular adhesion under arthroscopy between patients with and without a history of joint puncture. PATIENTS AND METHODS: Eighty-nine patients with internal derangements of TMJ who underwent arthroscopic disc repositioning and suturing surgery from February 2008 to September 2008 were included in this study. Patients were divided into 2 groups based on whether the patient had undergone joint puncture before surgery or not. The diagnosis of intra-articular adhesion was made according to the manifestation under arthroscopy. Incidence and severity of intra-articular adhesion between these 2 groups was compared. RESULTS: The incidence of intra-articular adhesion in the patients with a history of puncture was 69.23%, which was higher than that in the patients without a history of puncture (24.36%). The difference was statistically significant (P < 0.05). The incidence of severe adhesions in patients with a history of joint puncture was also higher than that in patients without a history of puncture (26.09% vs. 2.56%, P < 0.01). CONCLUSIONS: Puncture may increase the risk of intra-articular adhesion in patients with internal derangement.

Marsupialization facilitates eruption of dentigerous cyst-associated mandibular premolars in preadolescent patients.

PURPOSE: The purpose of the present study was to investigate the eruption of dentigerous cyst (DC)-associated mandibular premolars after marsupialization in preadolescents. PATIENTS AND METHODS: The present study was a retrospective cohort study of preadolescent patients with DCs who were treated as outpatients at the Department of Oral and Maxillofacial Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine. For our study, the data from these patients were collected, and the eruption of the premolar teeth, along with related factors, such as the interval to eruption, cusp depth, angulation, cyst size, and eruption space, were analyzed for the cyst group compared with the noncyst control group. RESULTS: The mean age of the patients was 9.1 years. All teeth associated with DCs erupted successfully after marsupialization. The follow-up panoramic radiograph showed that the cysts had disappeared and had been replaced by regenerated bone. The initial panoramic radiograph showed the angulation of the teeth in the cyst group had a significantly larger inclination angle than did the teeth in the noncyst group (P < .05). However, no significant difference was found for cusp depth, root formation, or space measurement. The gender, age, cusp depth, angulation, and eruption space were not factors influencing the eruption of the DC-associated tooth for preadolescent patients in the present study. In addition, the cyst-associated teeth took less time to erupt than the teeth in the control group. CONCLUSIONS: The results of the present study suggest that DC-associated mandibular premolars can erupt spontaneously after marsupialization in preadolescents.

An orthodontic technique for minimally invasive extraction of impacted lower third molar.

PURPOSE: To present a novel orthodontic approach for minimally invasive extraction of impacted mandibular third molars (M3s) close to the inferior alveolar nerve (IAN). PATIENTS AND METHODS: Eight patients (8 M3s) requiring extraction of M3s were included in this study; there were 2 cases of horizontal impaction, 4 of mesioangular impaction, and 2 of vertical impaction. Cone-beam computed tomogram showed that the roots of impacted M3s in 2 cases interrupted the cortices of the mandibular canal, and those in the other 6 cases were very close to the IAN. Orthodontic treatment was performed in this study. The crowns of 5 impacted teeth were surgically exposed before the application of the orthodontic device, whereas bonding was performed directly to the occlusal surface of the other 3 M3s, which had partially erupted. The opposing maxillary M3s were removed in 3 cases. One-step orthodontic extraction was applied to vertically impacted M3s and 2-step treatment was applied to horizontally or mesioangularly impacted M3s. Success was defined as the separation of the impacted tooth from the IAN as visualized on cone-beam computed tomogram. RESULTS: After orthodontic treatment, all impacted M3s were extruded and separated from the IAN (mean, 6.6 months; range, 4 to 10 months), without any neurologic consequences. The average time of extraction was 5 minutes. In all 8 cases, new bone formation occurred distal to the adjacent second molar. CONCLUSION: This orthodontic technique may be a minimally invasive approach for the extraction of impacted M3s adjacent to the IAN, with a decreased risk of paresthesias and with osteoperiodontal advantages.

Anatomic relationship between impacted third mandibular molar and the mandibular canal as the risk factor of inferior alveolar nerve injury.

Our aim was to explore the relation between the site of the mandibular canal and neurosensory impairment after extraction of impacted mandibular third molars. We organised a retrospective study of 537 extractions in 318 patients in which the affected tooth was intersected by the mandibular canal. This was verified by cone-beam computed tomography (CBCT), and we analysed the relation between the site of the canal and the likelihood of injury to the inferior alveolar nerve (IAN) after extraction of the third molar. The relation between the position of the root of the tooth and the mandibular canal was categorised into 4 groups: I=root above the canal; II=on the buccal side; III=on the lingual side; and IV=between the roots. The overall rate of neurosensory impairment after extraction was 6% (33/537). It occurred in 9/272 patients (3%) in group 1, 16/86 (19%) in group II, and in 8/172 (5%) in group III. There was no neurosensory impairment in group IV where the canal was between the roots. There were significant differences between group II and groups I and III (p<0.01), but not between groups I and III (p=0.32). The risk of damage to the inferior alveolar nerve is increased if third molars intersect with the mandibular canal, particularly on its buccal side.

Synovial chondromatosis of the temporomandibular joint with articular eminence extension.

Synovial chondromatosis (SC) of the temporomandibular joint is a rare benign lesion that can extend to the adjacent bony tissue. Most studies in the literature reported cases of SC of the temporomandibular joint with extension to the skull base, but there has been no report of intracranial extension through the articular eminence. The current study reports on the case of SC with articular eminence extension that was treated via combined trans-zygomatic tempora and preauricular approach and acquired good effect with 44 months of follow-up.

Arthroscopic management for synovial chondromatosis of the temporomandibular joint: a retrospective review of 33 cases.

PURPOSE: To present clinical, radiologic, and arthroscopic results of patients with synovial chondromatosis of the temporomandibular joint; to introduce a technique for removal of loose bodies in different areas; and to summarize the indications of therapeutic arthroscopy according to the magnetic resonance imaging (MRI) features. PATIENTS AND METHODS: From April 2001 to April 2010, 33 consecutive patients underwent arthroscopy. Their demographics, clinical manifestations, imaging studies, arthroscopic findings, treatments, and outcomes were reviewed. RESULTS: The predominant symptoms were pain, limitation of mouth opening, and joint sounds. Obvious joint effusion was shown on MRI in 21 of 33 patients. Mass lesions were shown on MRI in 29 of 33 cases. The presence of loose bodies was shown in 31 cases under an arthroscope. Synovial hyperplasia was noted in 12 patients. Bony erosion of the articular surface was discovered in 11 patients. Thirty-two patients underwent therapeutic arthroscopy. Smaller loose bodies were commonly removed with joint lavage or biopsy forceps in 24 patients. Fragmentation with forceps or a wider additional incision was applied to remove larger loose bodies in 7 patients. Debridement was applied to remove intrasynovial lesions in 7 patients. Coblation was used to remove the hyperplastic synovium in 10 of 32 patients. Eight patients were lost to follow-up. The mean follow-up period was 38 months. No recurrence was suspected clinically and radiologically. CONCLUSIONS: Therapeutic arthroscopy was appropriate for patients with separate mass lesions and no extra-articular extension. Surgical treatment comprised thorough removal of loose bodies and affected synovial tissues.

Problem-based learning in oral and maxillofacial surgery education: the Shanghai hybrid.

PURPOSE: A new hybrid course was designed for the practice of oral and maxillofacial surgery education, which included a problem-based learning (PBL) preclinical course and a 1-year clinical rotation under supervision. The aim of this study was to evaluate the effect of this hybrid course. MATERIALS AND METHODS: Eighty-seven students were included from 2006 to 2008. Of these students, 43 received PBL courses and 44 received traditional lecture-based courses. All the students took multiple-choice examinations before and after their clinical rotations. A self-assessment questionnaire was completed after completion of all preclinical courses. At the end of the 1-year clinical rotation, all students were asked to take the clinical skill test. We used t tests to assess the statistical significance of any changes in their scores. RESULTS: Students' scores on the multiple-choice examination showed significant improvement after taking both the PBL courses and the traditional lecture-based courses. The PBL group had better results regarding their overall scores than did the traditional group. The PBL group received higher scores in the "case analysis" and "operational skills" categories. The self-assessment showed that PBL students had more initiative to study in the library, a greater inclination toward teamwork, and more self-confidence before clinical practice. CONCLUSIONS: PBL courses combined with supervised clinical rotation were shown to improve students' operative skill, enhance their ability to perform case analysis, and improve their self-confidence. However, to determine the long-term effect after graduation, further series of testing should be performed in these students over the next few years.

Synovial chondromatosis in the inferior compartment of the temporomandibular joint: different stages with different treatments.

PURPOSE: To discuss a new classification and the treatment principles of synovial chondromatosis (SC) in the inferior compartment of the temporomandibular joint (TMJ). PATIENTS AND METHODS: Five cases of SC in the inferior compartment were treated in an open manner between January 2008 and May 2011. Each case had different clinical and radiologic aspects and was treated with different surgical therapies. SC in the inferior compartment of the TMJ is classified into 3 stages. All patients were evaluated by computed tomography, magnetic resonance imaging, and clinical manifestations preoperatively and postoperatively. RESULTS: There were 3 kinds of manifestation modes from radiologic findings. Case 1 was in stage 1, in which multiple loose bodies are noted without bony erosion. This patient was treated by removal of loose bodies and affected synovium. Case 2 was in stage 2, in which multiple calcified nodules were conglutinated to the condyle; the condyle was enlarged with pressure erosions. This patient was treated by condylectomy and reconstruction with costochondral graft. Case 3, case 4, and case 5 were all in stage 3, in which the condyle was destroyed as a result of pressure erosions or by direct bony invasion of the mass and the inferior surface of the disc was involved. These patients were treated by condylectomy together with discectomy, as well as reconstruction with costochondral graft and pedicled deep temporal fascial fat flap. No recurrence occurred. The height of the ramus and the occlusion were maintained in the same condition as preoperatively. CONCLUSIONS: Our new classification of SC in the inferior compartment of the TMJ can better guide clinical treatment.

Changes in disc position, disc length, and condylar height in the temporomandibular joint with anterior disc displacement: a longitudinal retrospective magnetic resonance imaging study.

PURPOSE: To quantitatively assess the changes in disc position relative to the condyle, disc length, and condylar height, with magnetic resonance imaging in patients with anterior disc displacement of the temporomandibular joint who had received no treatment, to provide useful information regarding treatment planning. PATIENTS AND METHODS: The study included 83 joints in 62 patients. The joints were assessed quantitatively for the disc position relative to the condyle, disc length, and condylar height on magnetic resonance imaging scans of the temporomandibular joint at initial and follow-up visits. Student t tests were used to assess the statistical significance of the changes. RESULTS: The mean age at first visit was 30.4 years. The mean follow-up interval was 10.9 months. Thirty-nine joints were shown to have disc displacement with reduction at the initial visit. Of these joints, 27 changed to having disc displacement without reduction after follow-up. The mean disc position relative to the condyle changed from 5.28 to 6.73 mm, whereas the mean disc length changed from 8.31 to 6.91 mm and the mean condylar height from 5.21 to 4.65 mm. Differences were all statistically significant. CONCLUSIONS: The disc would likely become more anteriorly displaced and shortened and the condylar height would decrease during its natural course. However, further stratified studies with longer follow-up are necessary.

Malocclusion as a common occurrence in temporomandibular joint arthroscopic disc repositioning: outcomes at 49 days after surgery.

PURPOSE: To evaluate the incidence, clinical manifestation, and prognosis of malocclusion after arthroscopic disc repositioning and suturing of the temporomandibular joint (TMJ). PATIENTS AND METHODS: The study included 211 patients (270 joints) with internal derangement of the TMJ who underwent arthroscopic disc repositioning and suturing from November 2005 to August 2006. The occlusion was checked and recorded preoperatively and at different intervals (0, 3, 7, 14, 21, 28, 35, 42, and 49 days after surgery) for all patients. The incidence of malocclusion after surgery was determined for every follow-up period. The χ(2) test was applied to assess the statistical significance of the changes of the incidence of malocclusion. RESULTS: The incidences of malocclusion were 100%, 80.1%, 67.8%, 46.9%, 28.9%, 18.0%, 15.7%, 14.6%, and 14.2% at 0, 3, 7, 14, 21, 28, 35, 42, and 49 days after surgery, respectively. There was a significant difference between neighboring follow-up periods within 28 days after surgery, whereas there was no significant difference from 28 to 49 days after surgery (P > .05). The main clinical manifestations of malocclusion were posterior open bite on the surgery side, incisal prematurities, and mandible midline deviated or nondeviated. CONCLUSION: Malocclusion commonly occurs after TMJ arthroscopic disc repositioning and suturing. However, it will improve within 28 days after surgery in most patients. If malocclusion lasts over 28 days, appropriate treatments should be considered.

Use of Coblation in arthroscopic surgery of the temporomandibular joint.

PURPOSE: To evaluate the effectiveness of Coblation in temporomandibular joint (TMJ) arthroscopic surgeries and to preliminarily evaluate the clinical effects. MATERIALS AND METHODS: Arthroscopic Coblation, combined with disc suturing, was performed in 419 TMJs from July 2001 to March 2007 by use of the ArthroCare System 2000 radiofrequency machine (ArthroCare, Sunnyvale, CA). All patients had stage II to V internal derangement, according to the classification of Wilkes. Besides disc suturing, the technique of Coblation was used in procedures of adhesion ablation, anterior release, chondroplasty, and discoplasty. All patients were followed up for 3 months and evaluated based on immediate arthroscopic findings, by clinical examination, and by magnetic resonance imaging examination. RESULTS: During the TMJ arthroscopic surgeries, the adhesion, unhealthy disc, and cartilage were ablated completely. The surface of the cartilage and disc were smooth without cautery damage and hemorrhage. During the clinical follow-up period, 76.37% of TMJs (320/419) had excellent results and 16.47% (69/419) had good results. The success rate was 92.84%. Masseter muscle atrophy occurred in 4 patients, and 30 TMJs required second arthroscopic surgeries or open surgeries. CONCLUSIONS: The technique of Coblation has proved to be an effective and minimally invasive option for the treatment of TMJ internal derangement, with advantages such as offering a high degree of precision and control, causing little or no thermal damage to surrounding tissue, leaving smooth anatomic surfaces, and achieving hemostasis of smaller blood vessels.

Arthroscopic management of septic arthritis of temporomandibular joint.

This article reports on 7 patients with septic arthritis of the temporomandibular joint (TMJ) who were managed with arthroscopy between 1998 and 2007. The common symptoms were trismus and pain. A series of imaging studies showed widening of joint space in 1 patient with plain film; MRI demonstrated increased joint effusion in 4 patients; accompanying cellulitis in adjacent tissues was discerned by CT in 2 patients. Under the arthroscope, a reddened and swollen synovial membrane was found in 2 patients who were in the acute stage, whereas strong adhesions, destruction of cartilage, and bony defects were discovered in other 5 patients in the chronic stage. Additionally, the disc was ruptured in 3 patients, and fibrosis was confirmed for 2 patients. Lavage, lysis of adhesion, and debridement of articular surface were common procedures for treatments. The average follow-up period was 57.4 months, and no recurrence was found. Arthroscopy has proven to be a useful method for management of septic arthritis of TMJ, especially for patients in the chronic stage.

New arthroscopic disc repositioning and suturing technique for treating internal derangement of the temporomandibular joint: part II--magnetic resonance imaging evaluation.

PURPOSE: To evaluate the efficiency of an arthroscopic suturing technique for stabilizing anteriorly displaced discs in patients with internal derangement of the temporomandibular joint (TMJ) by magnetic resonance (MR) imaging. PATIENTS AND METHODS: Six hundred thirty-nine patients (764 joints) diagnosed as having stages II to V of internal derangement were treated with arthroscopic disc repositioning and suturing from August 2004 to March 2007. Consecutive MR images were used to evaluate internal derangement before and approximately 1 to 7 days after the operation for all 639 patients. The disc position of the TMJ was judged according to the success criteria, which included 3 different sagittal planes (lateral, central, and medial). Operative efficiency in those patients, whose discs of the TMJ were affirmed to be in a normal position in all 3 planes, was evaluated to be excellent. Those patients whose discs were in a normal position in 2 planes were evaluated to be good. The others were evaluated to be poor. Cases evaluated as excellent and good were considered success cases (if the disc is displaced only in 1 or 2 planes before operation, the efficiency of the operation would be evaluated as a success only if the whole disc was in normal position). RESULTS: Postoperative consecutive MR images for all 764 joints confirmed that 95.42% (729/764) of the joints were excellent, 3.14% (24/764) were good, and only 1.44% (11/764) were poor. Repeated arthroscopic surgery or open surgery was carried out for the joints that were evaluated as poor. CONCLUSION: This study indicates that the TMJ arthroscopic suturing technique is effective in repositioning the TMJ disc as confirmed by an MR imaging examination, but long-term follow-up is necessary.

Septic arthritis of the temporomandibular joint: a retrospective review of 40 cases.

PURPOSE: Septic arthritis of the temporomandibular joint is an uncommonly reported entity. The aim of the present study was to review the cases treated at our clinic, analyze the characteristics of this disease and the responses to management, and recommend a protocol for managing suspected cases. PATIENTS AND METHODS: A total of 40 consecutive patients were included from 1995 to 2007. Their demographics, predisposing factors, clinical manifestations, radiologic findings, joint fluid analysis results, treatment, and outcomes were reviewed. RESULTS: The 40 patients included 26 men and 14 women, with an average age of 36 years. Original infections were found in 15 patients (local spread in 4 and hematogenous dissemination from a distant site in 11). All patients complained of trismus and tenderness in the temporomandibular joint. Sudden malocclusion was found in 33 patients. Joint space widening and limitation of condyle movement were demonstrated by plain film in 33 patients. Increased joint effusion was confirmed by magnetic resonance imaging in 7 patients. Joint fluid was obtained from 35 patients. A high level of neutrophils and fibrin were found under microscopy with hematoxylin-eosin staining. Staphylococcus saprophyticus and S. aureus were cultured from 5 patients. Arthrocentesis under low pressure was applied to 35 patients, and arthroscopy was used in 9 patients. Major sequelae occurred in 11 patients, including fibrosis in 2 and postinfectious osteoarthritis in 9. CONCLUSIONS: Septic arthritis of the temporomandibular joint mainly arises from hematogenous spread, but the original infection is often occult. Antibiotic therapy, arthrocentesis under low pressure, and joint immobilization are recommended for patients in the acute stage. The common sequela is osteoarthritis.

Simultaneous pigmented villonodular synovitis and synovial chondromatosis of the temporomandibular joint: case report.

Pigmented villonodular synovitis and synovial chondromatosis are benign nonneoplastic proliferations originating in the synovium of unknown cause. Involvement of the temporomandibular joint (TMJ) is rare. Only 3 cases of simultaneous pigmented villonodular synovitis and synovial chondromatosis involving the TMJ have been reported. The authors report the case of a 21-year-old female with simultaneous involvement of pigmented villonodular synovitis and synovial chondromatosis in the left TMJ. Clinical examination and magnetic resonance imaging did not reveal the synovial lesions, and the diagnosis was made by arthroscopy and histological examination. The lesions were removed with arthroscopy, and the displaced disc was repositioned. The patient has been symptom-free for 13 months postoperatively.

A murine model for septic arthritis of the temporomandibular joint.

PURPOSE: This study was designed to establish a murine model of hematogenously acquired bacterial arthritis of the temporomandibular joint (TMJ) to investigate the pathogenesis of this rare TMJ infection. MATERIALS AND METHODS: One hundred forty mice were inoculated intravenously with 3 different staphylococcal suspensions. They were sacrificed at intervals between 1 day and 2 months. Bacterial cultures were obtained from peripheral blood, liver, kidney, TMJs, knees, and interphalangeal joints. The TMJs were collected for histopathological examination. RESULTS: Staphylococcus aureus, isolated from the joint fluid of a patient with septic arthritis of the TMJ, was recovered from the liver, kidneys, knees, interphalangeal joints, and TMJs of several animals. Blood cultures were negative. Acute septic arthritis of the TMJs was confirmed in several animals as soon as 4 days after inoculation. Histopathology showed severe damage to chondrocytes and collagen fibers in the condyles and discs, leading to extensive degenerative changes. All cultures were negative, and there were no histopathologic changes in animals inoculated with bacteria from the other sources. CONCLUSIONS: A murine model for hematogenous septic arthritis of the TMJ was successfully developed with S. aureus isolated from a patient with a TMJ infection. The bacteria induced multiple organ and joint infections. Septic arthritis of the TMJ occurred in 21% of the animals inoculated. Onset was rapid. It produced extensive degenerative changes. The study confirms the need for prompt diagnosis and treatment of patients with septic arthritis. The model may prove to be very useful in the study of this rare infection.