The temporomandibular joint

MRI is the procedure of choice for diagnosing most internal derangements. MRI provides images that not only demonstrate bony detail but show excellent representation of soft tissues in both anatomic and semifunctional relationships. MRI does not use ionizing radiation and has no known adverse effects. Multiplanar imaging allows a three-dimensional analysis of the TMJ, providing a more complete assessment of the condyle, articular disc, fossa relationships. Whenever capsular adhesions or disc perforations are suspected and are not demonstrated with MRI, then arthrography should be performed.     

Traumatic temporomandibular joint injuries

Injuries of the temporomandibular joint are mostly due to injuries or fractures of the mandibular condyle. Fractures of the skull base involving the temporomandibular joint are rare. Classification of fractures refers to their anatomical positions and the presence or absence of a luxation. Further, it is important whether the fracture is intra- or extracapsular. The primary imaging method should be orthopantomography. As for therapy planning, especially surgery, also evaluation of soft tissue is necessary, computed tomography is the imaging method of choice. For diagnosis of complications or internal derangement of the temporomandibular joint, magnetic resonance imaging is to be recommended.     

Postoperative temporomandibular joint diagnosis

Postoperative management of patients suffering from symptoms of the temporomandibular joint does not differ considerably from the one of preoperative examination protocols. Knowledge of previous surgery helps to plan patient work-up and to interpret normal postoperative findings (eminectomy, discectomy, susceptibility artefacts from metallic residues...) and typical complications (intraarticular loose bodies, dislocations, avascular necrosis, foreign body granulomatous reactions) appropriately.     

超声引导关节腔内注射富血小板血浆治疗颞下颌关节紊乱的疗效分析

【摘要】　目的?评估超声引导下关节腔中注射富小板血浆（PRP）治疗颞下颌关节紊乱病的有效性。方法?2016年4月至2018年4月,门诊诊治45例确诊为颞下颌关节紊乱患者,超声引导将采集于患者自身的PRP注射于患者病变的颞下颌关节腔内。观察患者在治疗前和治疗后1、3和6个月的最大张口度,及颞下颌关节在静息、运动和咀嚼时VAS评分。结果?关节腔内注射PRP可有效改善最大口腔开放程度,颞下颌关节在静息,运动和咀嚼时VAS评分与治疗前相比显著降低。结论?超声引导下关节腔内注射PRP可显著改善颞下颌关节紊乱患者的体征和症状。     

Imaging of the temporomandibular joint

The recent advances in imaging of the temporomandibular joint (TMJ), especially the introduction of MR imaging and surface colls allowing precise visualization of superficial structures led us to reconsider the different techniques used in this very complex anatomical region, due to both its morphology and function. We also tried to determine their respective role, especially in the study of TMJ dysfunction syndromes, that represent the most frequent pathology of this region. Conventional radiography allows us to appreciate the overall amplitude of the joint movements, and to study bone abnormalities, but CT is much more precise in the study of cortical bone. In TMJ dysfunction, the joint itself is studied by either arthrography or MRI, but both techniques have their limitations and remain complementary in some aspects, which are detailed here, so that the choice between them depends on availability and therapeutic indications.     

Imaging of the temporomandibular joint

Both arthrography and MR imaging are of proven value in the evaluation of internal derangements of the TMJ. Arthrography provides the advantages of a dynamic display of joint mechanics and the easy detection of disc perforation. Its disadvantages include its technical difficulty and its poor visualization of the disc in the medial-lateral plane. MR imaging of the TMJ provides excellent soft-tissue detail and more readily demonstrates medial and lateral displacements of the disc. Unfortunately, perforations of the disc or ligaments are not usually visualized, and bony detail is not seen as well as on plain radiographs or computed tomography. In addition, real-time dynamic imaging of joint mechanics is not readily available. Currently, the choice of imaging modality is based on the specific diagnostic question, and availability of arthrography and MR imaging.     

CT morphology and function of the temporomandibular joint following conservative functional treatment of temporomandibular joint fractures

In 8 adult and 13 adolescent individuals who had undergone conservative treatment for condylar fractures 4.2 and 4.5 years earlier, respectively computed tomography was performed. In addition, joint mobility was examined clinically in 18 of these patients. The results of the radiological examination allow discrimination between high-grade and low-grade remodeling and excessive bone formation. With one exception, high-grade remodeling was invariably observed after childhood fractures. In the adult patients new bone formation was rarely observed. Correlation between the morphologic appearance and joint mobility was detectable only in cases of severely limited function. In the presence of less severe functional lesions, the size of the insertion area of the lateral pterygoid muscle might indicate the degree of functional rehabilitation. The radiological procedure is discussed.     

Pathologic-sonographic correlation in temporomandibular joint pathology

The accuracy of high-resolution ultrasonography (HR-US) in detecting disk displacement and condylar erosion of the temporomandibular joint (TMJ) was evaluated, using corresponding cryosections as a “gold standard”. HR-US of the TMJ was performed with a high frequency 12 MHz transducer on 30 preserved autopsy specimens. Succeeding sonography, the autopsy specimens were deep-frozen and cut in paracoronal planes corresponding to the sonographic images. HR-US diagnoses were compared with cryosectional findings in a blinded fashion. HR-US detected 19 (95%) of 20 instances of condylar erosion and 16 (73%) of 22 instances of disk displacement. There were one false-positive finding for condylar erosion and two false-positive findings for disk displacement. The accuracy of HR-US evaluating condylar erosion and disk displacement rated 93% and 73%, respectively. In conclusion, condylar erosion was reliably assessed by HR-US, but the evaluation of disk position was less accurate.     

Non-neoplastic arthropathies of the temporomandibular joint

The pathologic conditions that involve the TMJ are similar to those conditions that involve other joints in the body. Therefore, many of the radiologic characteristics are also similar. Nevertheless, because of the complex structure and function of this small joint, it is essential to know the variety of diseases that can involve the temporomandibular joint. It is also important to understand that functionally both TMJ's act as a single unit and that any alteration in function caused by a pathologic process on one side may lead to dysfunction on the contralateral side. It is essential that the radiologist is familiar with the principles of TMJ function as well as TMJ pathology.     

The temporomandibular joint in rheumatoid arthritis

The temporomandibular joint (TMJ) was investigated clinically and by orthopantomography in 110 patients with rheumatoid arthritis (RA) and in 73 control subjects. Clinical symptoms in the TMJ were established in 34 per cent of the RA patients and in 18 per cent of the controls. Radiographic abnormalities were found in 60 per cent of the RA patients compared with 15 per cent in the controls. No single radiographic abnormality was characteristic of joint involvement by RA. The most common radiologic features in RA patients were changes in the morphology of the condylar head and articular eminentia, marginal irregularities, reduced mobility, and an anterior position of the condylar head. No abnormalities were encountered in the early stage of the disease, which at least in part could be attributed to the inherent limitations of orthopantomography. The incidence of joint lesions increased with duration of the RA.     

Surgical indications in temporomandibular joint dysfunction

There has been a renewed interest in diseases of the temporomandibular joint over recent years due to a better understanding of the pathophysiology improvement in surgical techniques and, most importantly, the development of multidisciplinary teams. The indication for surgery is still essentially clinical, although medical imaging is increasingly informative. Arthrotomography provides the most reliable information. However, continuing progress in magnetic resonance imaging will probably provide surgeons with the best indications in the future. In this article, the authors clearly distinguish between intra-articular disk and muscular diseases. The operative indications are discussed in relation to the clinical signs and the condition of the joint.     

Common abnormalities in temporomandibular joint imaging

Magnetic resonance imaging has evolved as a prime diagnostic method for soft-tissue abnormalities of the temporomandibular joint. The most common temporomandibular joint abnormalities are internal derangement and osteoarthritis, but there are many other reasons for pain and dysfunction that are often overlooked. The purpose of this paper is to illustrate several of these more unusual and less well-recognized causes for temporomandibular joint pain and dysfunction. For example, internal derangement is often seen in asymptomatic individuals. Another purpose is to illustrate the difference in magnetic resonance imaging of asymptomatic and symptomatic internal derangement.     

Osteochondritis dissecans of the temporomandibular joint

A case is reported of a 43-year-old female patient presenting bilateral osteochondritis dissecans (OCD) of the temporomandibular joint (TMJ), in different stages for each side, associated with avascular necrosis (AVN) of the right condyle. Additionally observed was anterior disk displacement without reduction for both sides. We have proposed an adaptation of the previous classification of OCD for cases affecting the TMJ. We have also stressed the fundamental role of panoramic radiography on the diagnosis of stage 3 and stage 4 OCD of the TMJ. In relation to MRI, we have recommended sagittal (slice thickness of 2 mm) and coronal (slice thickness of 1 mm) fast spin-echo proton density-weighted sequences to better identify bone lesions (stage 1 and 2) and also localize osteochondral loose bodies; and coronal (slice thickness of 1 mm) fat-suppressed fast spin-echo T2 weighted sequence to better evaluate OCD (stable or unstable) and the features of the occasionally associated AVN (acute or chronic).     

Decompression sickness affecting the temporomandibular joint

Two cases of pain-only decompression sickness of the temporomandibular joint following altitude chamber exposure are presented. A detailed interview of both individuals revealed no other joint involvement or other complaints. A careful neurologic examination failed to disclose abnormalities. In both cases, the pain resolved completely with compression therapy, supporting the diagnosis of decompression sickness. Decompression sickness limited to this small joint is extremely rare, and may be easily confused with other causes of joint pain.     

Influence of mouthguard on temporomandibular joint

The aim of this study is to examine whether wearing a mouthguard (MG) has an influence on temporomandibular joint (TMJ) components (i.e., the condyle and the articular disk) and whether clenching with a resilient MG has an effect on the same components. Twenty-six healthy volunteers (15 females, 11 males) with an age range of 26-42 years old (median 28 years) participated in this study. Among all 52 joints in the 26 subjects, anterior disk displacement (AntDD) was recognized in 15. Thus, we classified the 52 joints into two groups, the AntDD group and the Normal group. Resilient thermoplastic materials were used to fabricate two types of MG, one that raised the vertical dimension height by 3 mm and another that raised it by 6 mm. Subjects were scanned with/without two types of MG with/without clenching by magnetic resonance imaging (MRI). The movement of the condylar head and articular disk was measured in the magnetic resonance images using the special subtraction technique. Wearing the MG without clenching did not have a negative influence on the TMJ and clenching in the Normal group. In the AntDD group, however, the relationship between the disk and condyle was affected by clenching and the degree of disk displacement was worsened by clenching with the thicker MG. From our results, we recommend that athletes with an internal derangement of the TMJ not wear the thicker MG and attention should be paid to its setting. And the subtraction technique using MRI was thought as a good tool for detecting a slight change in the TMJ.