Intraoperative complications in temporomandibular joint arthroscopy: A retrospective observational analysis of 899 arthroscopies

This study aims to describe intraoperative complications in temporomandibular joint arthroscopy in patients with Wilkes stage II, III y IV. An analytic observational retrospective study. Inclusion criteria were patients who had no improvement with conservative treatment diagnosed as Wilkes II stage to Wilkes stage IV, and no previous TMJ surgery. Exclusion criteria were disc perforation observed by arthroscopy. Data collected from 458 patients (899 arthroscopies). Of this population, 772 (85.8%) arthroscopies correspond to women, and 127 men (14.1%). Of the sample evaluated, 368 (40.9%) were arthroscopic without discopexy, and 531 (59%) were arthroscopic with discopexy using resorbable pins. In total, 330 complications (36.7%) were found, of which 293 (32.5%) were implicated with iatrogenic damage to the anatomy, and 36 (4%) were associated with some instrument failure. Of this total number of complications, 191 (51.9%) of 386 corresponded to the arthroscopy without discopexy group and 138 (25.9%) of 531 corresponded to the arthroscopy with discopexy group. These study data suggest that the main complications were irrigation fluid extravasation (p = 0.000), and intra-articular bleeding (p = 0.001) followed by pin problems (p = 0.001) in cases of arthroscopies with discopexy. Within the limitations of the study it seems that the learning curve has an important influence on the occurrence of complications. At the beginning of the learning curve, complications are more related to anatomy. Afterwards, the rate of complications decreases but they are more related to the instruments used in advanced techniques. Therefore, proper training and a wide learning curve can reduce the risk of complications and if any occur, more timely management could be given.     

Regulatory effects of biophysical strain on rat TMJ discs

Recent studies have revealed that dynamic biomechanical forces can exert antiinflammatory and antiproteolytic effects on fibrocartitage. Whether the effects of mechanical strain also involve stimulation of the insulin-like growth factor (IGF) system and, therefore, of growth and repair of fibrocartilage has yet to be determined. The objective of this in vitro study was to determine if continuous biophysical strain regulates the gene expression of IGF1, IGF2, IGF1 receptor (IGF1R), insulin receptor substrate (IRS1), and IGF-binding proteins (IGFBP) 3 and 5 in cells from the fibrocartilaginous disc of the temporomandibular joint (TMJ). Rat TMJ disc cells were subjected to continuous biophysical strain (3% and 20%) for 4 and 24 h. Subsequently, RNA was extracted and real-time PCR was performed using an iCycler iQ detection system to analyze the gene expression of the IGF system. The gene expression of IGF1, IGF2, IGF1R, IRS1, IGFBP3, and IGFBP5 was significantly (p < 0.05) inhibited when cells were subjected to continuous biophysical strain, as compared to control at both time points. High strain induced a stronger inhibition of these molecules as compared to strain of Low magnitude. In conclusion, continuous biophysical strain seems to downregulate the expression of the IGF system and may, therefore, reduce the potential of fibrocartilage for growth and repair.     

Correlation of MRT imaging with real-time axiography of TMJ clicks

There is a series of tools useful for gathering diagnostic information on patients with temporomandibular joint disorders. Tracings of the joint movement (axiography) provide useful information about the motion of the joints. Since the availability of electronic axiographic tracers, the movement of the condyles can be resolved with high resolution both in space and in time. In order to obtain information about the anatomical relation of the joint surfaces and the disc, magnetic resonance tomography imaging (MRI) is routinely carried out. It is common practice to take MR images of the joints with the mouth closed and fully open. In order to correlate the MR images with the axiographic tracings, a series of images can provide much more information. In this study we examined patients with distinct temporomandibular joint (TMJ) clicks. In one case, the click occurs once a day, while in the other case the click happens every time the mouth is opened. In order to obtain information about both motion and anatomical relation of the TMJ at and around the position where the clicks occur, we recorded a series of MRI scans with the mouth gradually opened and before and after joint clicks. Real-time axiographic tracings during the click were taken with an optimized system where the polar moments were reduced as much as possible to follow the movement during the click. These tracings were correlated with the MRI scans to determine the exact internal conditions of the TMJ and the changes during the click. In particular cases, the additional information provided by this procedure can be useful in deciding whether and which therapeutic intervention is advisable.     

Design Characteristics for the Tissue Engineering of Cartilaginous Tissues

Tissues like the temporomandibular joint (TMJ) disc and the knee meniscus are often mistakenly viewed as a tantamount to hyaline cartilage, largely due to the absence of a comprehensive understanding of the distinguishing properties of cartilaginous tissues. Because of this confusion, fibrocartilaginous tissue engineering attempts may not be based on suitable experimental designs. Fibrocartilaginous tissues are markedly different than hyaline cartilage; however, the dearth of knowledge related to their cellular and biochemical composition, as well as their biomechanical characteristics, is stunning. Hyaline articular cartilage is exclusively composed of chondrocytes that produce primarily type II collagen, whereas the TMJ disc and the knee meniscus have a mixed cell population of fibroblasts and cells similar to chondrocytes, which predominantly secrete type I collagen. Additionally, fibrocartilaginous tissues have a low glycosaminoglycan content, a low compressive modulus, and a high tensile modulus when compared to hyaline cartilage. Therefore, it is crucial for fibrocartilaginous tissue engineering attempts to be tissue-specific, utilizing the knowledge of the distinct and unique properties of these tissues. At the same time, advances and insights related to the science and engineering aspect of hyaline cartilage regeneration must be carefully considered for the in vitro engineering of fibrocartilaginous tissues.     

Network of telocytes in the temporomandibular joint disc of rats

The phenotypes of the temporomandibular joint (TMJ) disc cells range from fibroblasts to chondrocytes. There are relatively few reported studies using transmission electron microscopy (TEM) to determine the ultrastructural features of these cells. It was hypothesized that at least a subpopulation of TMJ stromal cells could be represented by the telocytes, cells with telopodes. In this regard a TEM study was performed on rat TMJ samples. Collagen-embedded networks were found built-up by cells with telopodes with subplasmalemmal caveolae, moderate content in matrix secretory organelles and well-represented intermediate filaments. Appositions of cell bodies were found. Prolongations of such cells were closely related to nerves and microvessels. Our study indicates that the TMJ disc attachment seems equipped with telocytes capable of stromal signaling. However, further studies are needed to assess whether the telocytes belong to a renewed cell population derived from circulating precursors.     

Biomechanical simulation of temporomandibular joint replacement (TMJR) devices: a scoping review of the finite element method

The aim of this study was to perform a literature review on the use of finite element modeling (FEM) for the evaluation of the biomechanical behavior of temporomandibular joint replacement (TMJR) devices. An electronic search of online medical and scientific literature database was conducted using selected search terms. The search identified 307 studies, of which 19 were considered relevant to this study. Of the 19 selected studies, 10 (52.6%) investigated the influence of geometry and fixation methods, while two (10.5%) evaluated the behavior of artificial condyle–fossa structures. The TMJR devices assessed in these studies included TMJ Inc. (aka Christensen; 63.2%), Zimmer Biomet (15.7%), Stryker (10.5%), and a theoretical intramedullary condylar component (5.3%); 26.3% of the studies evaluated custom TMJR devices. Such studies provided important data on the distribution of strain and stress through TMJR structural components and surrounding bone by using different software systems and methods. The mean stress values were lower on a custom TMJR condyle–ramus component and the supporting bone than on the stock device. FEM proved to be an accurate and valuable biomechanical simulation tool for studying the current TMJR devices and should be considered a useful tool for the improvement and development of future joint replacement devices.     

Editorial: Kungl. Karolinska Medico-Kirurgiska Institutet 1810-1960

Abstract

Objective. The first aim of this study was to examine a contemporary human skull material for possible ethnic differences in respect of degenerative changes in the temporomandibular joints (TMJs). A second aim was to see if there was any correlation between such changes and occlusal support in any of the two groups and, if so, if this correlation was sex-related. Materials and methods: The material consisted of 129 Caucasian skulls and 76 skulls from Afro-Americans. Ninety-four of the Caucasian skulls came from males (73%) and the corresponding figure for the Afro-Americans was 40 (53%). Their mean age at death was 46 years (range: 19–89 years) and 37 years (range: 18–70 years), respectively. Results. Dental status was in general poor and 13% of the Afro-Americans and 26% of the Caucasians were edentulous. Form and surface changes of the TMJs were more common in the present material compared to most previous studies. No differences could be found between the two ethnic groups in respect of degenerative joint changes in the TMJs. In men, no correlation of clinical relevance could be found between severity of joint changes and occlusal support. However, in both Caucasian and Afro-American women, such a correlation was obvious, especially in higher age. Conclusions. The present findings give no evidence for any differences in the prevalence of degenerative changes in the TMJs in Caucasians and Afro-Americans. The strong correlation found between such changes and occlusal support in women but not in men might be explained by hormonal differences.     

Clinical outcome after 36 months of treatment with injections of autologous blood for recurrent dislocation of the temporomandibular joint

We investigated the prognosis after three years of treatment for recurrent dislocation of the temporomandibular joint with autologous blood given intravenously in 21 patients with a mean (range) age 64 (17-92) years of whom 16 had coexisting systemic disease. The mean (range) follow up from the first injection was 64 (41-99) months. Eighteen patients had no recurrence during the first 36 months after their first injection, which showed that this minimally-invasive treatment was effective, particularly for those who had conditions that made a mouthpiece or operation unsuitable.     

Reconstruction of the mandibular condyle using the microvascular lateral femoral condyle flap

The lateral femoral condyle (LFC) flap is a new flap first reported in 2015 for the treatment of osteomyelitis in hand surgery. This paper introduces a technique of osteochondral LFC flap harvest for mandibular condyle reconstruction and reports on the use of this flap in temporomandibular joint reconstruction. For condyle resection, a pre-auricular approach saving the temporal artery and vein is performed. A step osteotomy technique is used for condyle resection. LFC harvesting starts with dissection of the popliteal artery and vein. The superior genicular artery and vein are identified and followed along their periosteal branches. An osteochondral flap according to the condyle defect is harvested from the anterior pole of the knee. The flap is banded according to the defect and fixed to the mandibular neck with three miniscrews. Follow-up computed tomography scans should be performed at 1 week, 6 months, and 1 year after surgery. The case of a 58-year-old female patient with osteomyelitis of the left mandibular condyle after multiple preoperative therapies is reported. The LFC flap technique was used for left condyle reconstruction, resulting in good functional and morphological outcomes at the 6-month postoperative follow-up. In conclusion, the osteochondral LFC flap is a new and promising technique for mandibular condyle reconstruction for special indications.