A Retrospective Cohort Study of Risk Factors for Descending Necrotizing Mediastinitis Caused by Multispace Infection in the Maxillofacial Region.

PURPOSE: Descending necrotizing mediastinitis (DNM) has been the most common life-threatening complication of multispace infection (MSI) in the maxillofacial region owing to the lack of a timely diagnosis and treatment. We assessed the clinical characteristics and diagnosis of odontogenic MSI and evaluated the risk factors for DNM caused by MSI. PATIENTS AND METHODS: We performed a retrospective cohort study of inpatients with MSI in the maxillofacial region from January 2012 to October 2016. The patients were classified into a non-DNM group and a secondary DNM group. The information collected included gender, age, systemic comorbidities, source of maxillofacial infection, computed tomography imaging data, and laboratory test results. Univariate analysis (t test and χ2 test, or the Fisher exact test) and logistic regression analysis were applied. RESULTS: A total of 296 patients were included. The mortality was 6.3%. On univariate analysis, the following factors were statistically significant: gender (P = .001); age (P = .003); source of infection (P = .004); number of affected spaces (P < .001); involvement of the parotid space (P < .001), submandibular space (P < .001), subgingival space (P < .001), pterygomandibular space (P < .001), parapharyngeal space (P < .001), and retropharyngeal space (P < .001); and percentage of neutrophils (P < .001). On multivariate analysis, the parapharyngeal space (P = .008), source of infection (P = .037), and number of affected spaces (P < .001) were statistically significant. CONCLUSIONS: Glandular infection, parapharyngeal space involvement, and the presence of multiple affected spaces were risk factors for DNM. Clinicians should vigilantly watch for these factors during clinical treatment and effective measures taken to prevent the occurrence of DNM as soon as possible.

Internal Jugular Vein Thrombosis With Serious Cervical Necrotizing Fasciitis.

Internal jugular vein thrombosis (IJVT) is a rare complication of cervical necrotizing fasciitis (CNF) which may lead to life threat. This article reports a patient with severe CNF complicated with IJVT, and combined with the literature to analyze the diagnosis and treatment of CNF and IJVT.

Risk Factors Affecting the Prognosis of Descending Necrotizing Mediastinitis From Odontogenic Infection.

PURPOSE: Descending necrotizing mediastinitis (DNM) is a serious complication of head and neck infections and has an excessively high mortality rate owing to the lack of understanding of DNM. We assessed the clinical characteristics, diagnosis, treatment, and outcomes of odontogenic DNM and evaluated the risk factors affecting the prognosis of DNM to provide an up-to-date overview for clinical practice. MATERIALS AND METHODS: We performed a retrospective cohort study, enrolling a sample of patients with DNM due to odontogenic infection who had been referred from January 2013 to December 2016. The patients were classified into surviving and deceased groups. The primary predictors in the present study were the presence of multiple comorbidities, complications, demographic data (age, gender), laboratory tests (white blood cell count, percentage of neutrophils), and time (duration before diagnosis, length of hospital stay). The primary outcome variable was the patient outcome (dead or alive). The continuous variables were evaluated using Student's t test or the t test, and the categorical and binary variables were compared using the χ2 test or Fisher exact test. RESULTS: A total of 81 patients (68 men, 13 women; median age of 57.2 ± 12.2 years) were included. The mortality was 4.9%. The most frequent cause of DNM was periapical periodontitis (66.7%). The lower posterior molars were involved in 39.5% of the cases. Treatment consisted of antibiotic therapy, aggressive transcervical mediastinal drainage (n = 74), and thoracotomy (n = 7). The associated risk factors for mortality were complications (P < .005) and severe sepsis or septic shock (P < .001) on bivariate analysis. CONCLUSIONS: Septic shock and complications were the risk factors that correlated with a poor prognosis. A timely diagnosis and use of aggressive mediastinal drainage are fundamental to reducing the incidence of complications and the development of septic shock in odontogenic DNM patients.

Diagnosis and Treatment of Gorham-Stout Disease in Maxillofacial Regions.

PURPOSE: This study was aimed to investigate the clinical features, imaging examination, and treatment of the patients with Gorham-Stout disease (GSD) in maxillofacial region, so as to improve the understanding of GSD. METHODS: The medical records of the patients with GSD who were referred to Shanghai Ninth People's Hospital from January 2010 to May 2016 were reviewed. Their ages, lesion location, imaging results, laboratory examination results, treatment, and therapeutic effects were analyzed. RESULTS: A total of 4 cases were included (males 2, females 2). The average onset age was 40 years. GSD attacked the mandible in 2 cases; mandible and temporal bone in 1 case; and mandible, temporal bone, and zygoma in 1 case. All cases were examined by computed tomography (CT), which showed bone resorption and atrophy of soft tissue in involved region. Four patients were given alendronate for treatment. All of them had no significant signs of progress after treatment. CONCLUSIONS: GSD can affect one single bone or multiple bones in maxillofacial region. The diagnosis mainly depends on the imaging examinations. Enhanced CT or magnetic resonance imaging is advocated for differential diagnosis of this disease. Alendronate was used with apparent good effect in these patients.

Is anterior disc displacement without reduction associated with temporomandibular joint condylar height in juvenile patients younger than 20 years?

PURPOSE: Because disc displacement might be accompanied by degenerative changes in the condyle, this study explored the association between condylar height and anterior disc displacement without reduction in juvenile patients. MATERIALS AND METHODS: This was a retrospective cohort study that enrolled a sample of patients younger than 20 years with unilateral disc displacement without reduction. All patients had 2 magnetic resonance imaging records taken from January 2010 to June 2013 (interval, >6 months). Condylar height, disc length, and displacement distance were measured. The predictor variable was joint status (healthy vs affected side), and the outcome variables were changes in condylar height, displacement distance, and disc length over time. SAS 9.13 was used for analysis and the P value was set at .05. RESULTS: One hundred twenty-four patients (101 female and 23 male; mean age, 16.4 yr; mean interval, 13.6 months) were included. During the interval, the condylar height of the healthy side increased 0.75 mm, whereas the condylar height of the affected side decreased 0.41 mm. The disc of the affected side was shortened and more anteriorly displaced. CONCLUSION: Anterior disc displacement without reduction could be accompanied by a decrease in condylar height in juvenile patients, and the disc might be shortened and more anteriorly displaced.

Multi-Space Infections in the Head and Neck: Do Underlying Systemic Diseases Have a Predictive Role in Life-Threatening Complications?

PURPOSE: To assess the incidence, risk factors, treatment, and outcomes of life-threatening complications of multi-space infections (LCMIs) in the head and neck. PATIENTS AND METHODS: This was a retrospective cohort study that enrolled a sample of patients with multi-space infections who were referred from February 2006 through July 2014. The patients were classified into LCMI and non-LCMI groups. The primary predictor in this study was underlying systemic disease. The primary outcome variable was LCMI. Univariate analyses were used for data statistics. RESULTS: A total of 549 patients were included, and an LCMI was found in 66 patients (12.20%). Descending mediastinitis was the most frequent LCMI (n = 37; 56.06%), followed by airway obstruction (n = 27; 40.91%), pneumonia (n = 12; 18.18%), pericarditis (n = 6; 9.09%), intraorbital infection (n = 2; 3.03%), multiple organ failure (n = 2; 3.03%), intracranial infection (n = 2; 3.03%), and sudden cardiac death (n = 1; 1.52%). Twelve patients with LCMI died during treatment. Elderly patients with an underlying systemic disease more commonly developed an LCMI. CONCLUSIONS: Multi-space infections in the head and neck can cause several life-threatening complications, and the morbidity of LCMI is considerable. Older age and underlying systemic disease can increase the risk of an LCMI.

Changes in the temporomandibular joint space after functional treatment of disk displacement with reduction.

This study aimed to evaluate the changes of temporomandibularjoint (TMJ) space in the treatment of disk displacement with reduction (DDWR) for class II cases. Forty-two adolescent patients with unilateral DDWR, who were successfully treated by functional appliance, were selected in this study. Magnetic resonance imaging scans were used before treatment (T1), at the start of treatment (T2), and after functional treatment (T3). Compared with the normal joint, the change of joint space index was calculated. The anterior, posterior, and superior joint spaces were analyzed on the largest sagittal plane among T1, T2, and T3. Student's t-test was used for statistical analysis. The mean treatment period was 10 months (6-16 mo). Functional appliance was effective in eliminating pain and clicking. During the phase of T1, the value of the joint space index of DDWR was significantly higher than that of the control (P < 0.05). There was a significant decrease in the anterior space and an increase in the postsuperior space at T2 (P < 0.01), and then the contrary changes occurred at T3. However, there was a significant increase in the postsuperior space and no significant decrease in the anterior space when T1 and T3 were compared. This study indicates that the TMJ space is well distributed after disk repositioning with functional treatment of DDWR. It is also suggested that the adaptive remodeling in TMJ occurs via functional treatment.

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.

Comparison of multi-space infections of the head and neck in the elderly and non-elderly people, part II: the influencing factors of the outcomes.

OBJECTIVE: This study aims to identify significant predictors of 3 outcomes in the aged patients and non-elderly with multi-space infections of the head and neck: the number of incisions, the length of hospital stay, and complications. PATIENTS AND METHODS: A retrospective study was conducted on 242 patients receiving treatment for severe multi-space infections of the head and neck region. Study variables were categorized as demographics, clinical parameters, and laboratory values. The outcome variables were the number of incisions, length of hospital stay, and complications. Multivariate linear and logistic regression techniques were used to measure associations between study variables and the outcome variables. Statistical analyses of the results between groups were performed using the Student t test and χ. RESULTS: Multivariate analyses, controlling for confounding variables, indicated that the number of spaces affected was a predictor of the number of incisions and complications in the elderly group. In the non-elderly group, the number of spaces affected was a predictor of the number of incisions and length of hospital stay. Admission blood glucose level and admission white blood cell count were the predictors of complications in the non-elderly. CONCLUSION: This study identifies different study variables as predictors of outcomes in treating multi-space infections of the head and neck in the elderly and non-elderly group. The number of spaces affected is the most important predictor.

Disc positions and condylar changes induced by different stretching forces in the model for anterior disc displacement of temporomandibular joint.

OBJECTIVE: The aim of this study was to compare the disc positions and condylar changes induced by different stretching forces in the modified animal model for anterior disc displacement (ADD) of the temporomandibular joint. METHODS: In the experimental group, 30 rabbits were equally divided into 3 subgroups and underwent surgical ADD via different stretching forces: group A with 0.5 N, group B with 1 N, and group C with 2 N. In the sham group, 6 rabbits underwent the same surgery without the disc being pulled anteriorly. The diagnosis of ADD was made when the anterior band of the disc was located anteriorly to the articular eminence. Histologic and radiographic changes of the condyles were observed under light microscopy and micro-computed tomography scanning 1 week after surgery. RESULTS: The success rates of ADD were both 100% in groups B and C and 70% in group A. The correlations between the stretching force and severity of ADD, the stretching force and severity of cartilage changes, and the severity of ADD and cartilage changes were statistically significant (P < 0.01). The most advanced ADD and severest condylar changes were induced in group C. Condylar remodeling and scleroses were found in micro-computed tomography scans. CONCLUSIONS: The rabbit model for ADD has been successfully established in this study, which is feasible and minimally invasive. The stretching force of at least 1 N could induce the disc displaced successfully. Larger stretching force would induce severer ADD and condylar degenerative changes.

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.

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.

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.

Is there association between severe multispace infections of the oral maxillofacial region and diabetes mellitus?

PURPOSE: This study aims to identify the impact of diabetes on the final outcome (length of hospital stay and development of complications) in patients with severe multispace infections in the head and neck. Furthermore, it intends to characterize significant clinical features of these patients compared with nondiabetics. MATERIALS AND METHODS: A retrospective study was conducted in 117 patients who received treatment for multispace infections of the head and neck region from 2007 through 2010 at the Department of Oral and Maxillofacial Surgery, Shanghai Ninth Hospital. The study identified diabetic patients and compared them with nondiabetic patients. Demographics, etiology of infection, clinical parameters (time from first onset of symptoms to hospital admission, number of spaces affected, and distribution of involved spaces), and laboratory values (bacteriology, admission blood glucose level, admission white blood cell count, and percentage of neutrophils on admission) were analyzed for clinical significance. Statistical analyses of the results between groups were performed using the Student t test, χ(2) test, variance analysis, logistic regression analysis, and linear regression analysis. RESULTS: Admission blood glucose level was the only factor influencing the complications in multispace infections in the oral-maxillofacial region. Compared with nondiabetic patients, diabetics had infections that involved more spaces, longer hospital stays, and more frequent complications. Some diabetic patients died. The disease status (with or without diabetes) was associated with clinical outcomes (length of hospital stay and complications) in the therapy procedures. CONCLUSIONS: This study identifies uncontrolled diabetes mellitus as an important indicator of clinical features and outcomes in treating multispace infections of the oral-maxillofacial region.

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.

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.

Prevention and treatment for the rare complications of arthroscopic surgery in the temporomandibular joint.

PURPOSE: To analyze the rare complications of arthroscopic surgeries in the temporomandibular joint (TMJ) and to investigate the preventive and treating methods. PATIENTS AND METHODS: In this study, 2,034 consecutive patients (2,431 joints), diagnosed as TMJ internal derangement, were treated by arthroscopic surgeries when visiting the TMJ clinic at the Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, between May 2001 and September 2009. The clinical complications were analyzed to investigate cause, prevention, and control measures. RESULTS: Of all 2,034 cases, the complications were shown as follows: 5 joint hemorrhages of the lateral pterygoid muscle vascular, injuries of the lateral pterygoid muscle nerve in 5 joints, 3 joints with broken instruments, rejection reaction in 2 joints, and perforation of tympanic membrane in 2 joints. CONCLUSIONS: Arthroscopic surgery was a safe and effective method to treat TMJ internal derangement; its complications were limited and acceptable, but an experienced operator was required for this surgical technique.