The Optimal Regimen for the Treatment of Temporomandibular Joint Injury Using Low-Intensity Pulsed Ultrasound in Rats with Chronic Sleep Deprivation.

Low-intensity pulsed ultrasound (LIPUS) is an emerging physical therapy for the treatment of early temporomandibular joint injury and has a good effect on promoting cartilage and subchondral bone tissue repair. However, the best LIPUS intensity and treatment duration remain unclear. This study is aimed at observing the preventive and therapeutic effects of different modes of LIPUS and at identifying the optimal LIPUS treatment regimen for temporomandibular joint injury. In the present study, rat models of temporomandibular joint injury were established using a chronic sleep deprivation (CSD) method, and the effect of LIPUS as intensities of 30, 45, and 60 mW/cm2 was observed at 7, 14, and 21 days. After CSD, the condylar cartilage of the rats demonstrated variable degrees of surface roughening, collagen fiber disarrangement or even partial exfoliation, decreased proteoglycan synthesis and cartilage thickness, decreased chondrocyte proliferation, decreased type 2 collagen (COL-2) expression, and increased matrix metalloproteinase- (MMP-) 3 expression at all three time points. When the rats with CSD received different intensities of LIPUS treatment, the pathological changes were alleviated to various extents. The groups receiving 45 mW/cm2 LIPUS showed the most significant relief of cartilage damage, and this significant effect was observed on days 14 and 21. These results demonstrated that LIPUS can effectively inhibit CSD-induced condylar cartilage damage in rats, and LIPUS treatment at an intensity of 45 mW/cm2 for at least 2 weeks is the optimal regimen for temporomandibular joint injury.

Effect of TLR4/MyD88 signaling pathway on expression of IL-1ß and TNF-α in synovial fibroblasts from temporomandibular joint exposed to lipopolysaccharide.

Accumulating evidence from previous studies suggested that interleukin-1 (IL-1ß) and tumor necrosis factor-α (TNF-α) play an important role in pathogenesis of temporomandibular disorders (TMD). However, the cell surface receptors and the intracellular signal pathways leading to these cytokines expression are not fully understood. In the current study, we investigated the roles of Toll-like receptor 4 (TLR4) and its adaptor myeloid differentiation factor 88 (MyD88) in the expression of IL-1ß and TNF-α in synovial fibroblasts (SFs) separated from rat temporomandibular joint (TMJ) with lipopolysaccharide (LPS) stimulation. The results showed that treatment with LPS could increase TLR4, MyD88, IL-1ß, and TNF-α expression at both mRNA and protein levels. In addition, increased expression of IL-1ß and TNF-α could be blocked by treatment with TAK-242, a blocker of TLR4 signaling, and also by MyD88 inhibitory peptide (MIP). These findings suggested that maybe TLR4/MyD88 signal transduction pathway participates in enhanced expression of IL-1 and TNF-α in patients with TMD. The activation of TLR4/MyD88 signal transduction pathway which results in production of proinflammatory factors may play a role in the pathogenesis of TMD.

Cytokines in healthy temporomandibular joint synovial fluid.

Analysis of temporomandibular joint (TMJ) synovial fluid may elucidate the aetiology of temporomandibular disorders and arthritic conditions, as well as the inflammatory mechanisms involved. Knowledge about healthy synovial fluid is necessary to understand TMJ pathologies. We aimed to quantify the proinflammatory cytokines interleukin (IL)-1ß, IL-2, IL-6 and tumour necrosis factor (TNF), and the anti-inflammatory cytokines IL-10 and interferon (IFN)-γ in healthy TMJ synovial fluid to serve as reference values for future studies on TMJ pathologies. Twenty healthy, young adult volunteers without temporomandibular dysfunction were included. Bilateral synovial fluid samples were obtained using the push-pull technique with hydroxocobalamin described by Alstergren in 1999. Cytokines were quantified with Luminex multiplex assays and compared using nonparametric statistical analysis. No serious adverse effects were reported. Of 40 possible samples, 14 fulfilled the strict sampling criteria and were included in the analysis. Cytokine values (reported as medians with interquartile ranges) were as follows: TNF, 23 (13-37) pg mL(-1) ; IL-2, 1·8 (0-22) pg mL(-1) ; and INF-γ, 10 (0-47) pg mL(-1) . IL-1ß, IL-6 and IL-10 were almost undetectable. In addition, TNF and INF-γ cytokine levels correlated. We demonstrated that TNF was consistently detected and IFN-γ and IL-2 sporadically detected in the TMJ synovial fluid of healthy individuals using the hydroxocobalamin method and a multiplex assay. The cytokines IL-10, IL-1ß and IL-6 were barely detectable in this sample of healthy TMJs.

Características fisicoquímicas e citológicas do líquido sinovial da articulação temporomandibular em eqüinos / Physical, biochemical and cytological characteristics of the equine temporomandibular joint synovial fluid

Foram estudadas as características fisicoquímicas e citológicas do líquido sinovial da articulação temporomandibular de dez eqüinos hígidos. Verificou-se que o líquido é viscoso, amarelo claro a citrino, límpido e livre de partículas à temperatura ambiente. Houve contaminação da amostra por sangue em três amostras que se apresentaram amarelo avermelhadas a vermelhas e de aspecto turvo. A taxa de glicose variou entre 100 e 250 e a concentração protéica não ultrapassou 3,8g/dL. O número médio de células nucleadas foi de 417 células/µL, com predominância de grandes células mononucleares e linfócitos. As mensurações das características pesquisadas no líquido sinovial da articulação temporomandibular de eqüinos são de execução simples e passíveis de implantação na rotina de atendimentos clínico-cirúrgicos.

Physical, biochemical and cytological characteristics of the temporomandibular joint synovial fluid were studied in ten clinically normal horses. It is a viscous, pale yellow, clear fluid and without flocculent material at room temperature. There was blood contamination in three samples, they presented red-yellow to red and cloudy. The range of glucose levels were 100 to 250 and its protein concentration was up to 3,8g/dL. Nucleated cells mean number was 417 cells/µL, with predominating large mononuclear cells and lymphocytes. Equine temporomandibular synovial fluids can be easily evaluated, being feasible in clinical and surgical routine, and the information may be useful to the diagnosis, treatment and prognosis of animals with temporomandibular alterations.

Tumoral calcium pyrophosphate dihydrate crystal deposition disease of the temporomandibular joint: identification on crystallography.

This paper reports a case of calcium pyrophosphate dihydrate (CPPD) crystal deposition in the temporomandibular joint (TMJ) of a 59-year-old man with the chief complaint of severe pain in the left TMJ. On CT a radiopaque area was seen around the condylar process of the left TMJ with irregular destructive bony changes. A provisional diagnosis of crystalline-induced arthritis was made on histopathology of a biopsy specimen. Electron probe microanalysis (EPMA), scanning electron microscopy (SEM) and X-ray diffraction showed both CPPD and hydroxyapatite (HA) in the crystalline materials. Identification of these two types of crystal in crystal deposition disease of TMJ, using crystallography, is discussed.

Analysis of estrogen binding sites of the posterior ligament of the human TMJ.

BACKGROUND: Conflicting results have been reported regarding the presence or absence of estrogen-binding sites (EBS) in the human temporomandibular joint (TMJ). The possible role of female sex hormones in the pathophysiology of internal derangement of the TMJ has been suggested to explain the prevalence of TMJ symptoms in female patients. PATIENTS AND METHODS: Posterior bilaminar tissue excised during TMJ articular disc repositioning and posterior ligament repair was taken from 28 patients (26 female, 2 male) for evaluation. Cryosections were stained using a monoclonal antibody (Mab) against EBS. To ensure efficacy of the antibody staining procedure, an internal positive control consisting of human breast tissue previously proven EBS-positive was used. No asymptomatic control TMJ tissue was available for our study. RESULTS: None (0%) of 28 TMJ tissue specimens showed nuclear-staining positive for the presence of EBS in the posterior bilaminar tissue of the TMJ. However, estrogen-binding sites associated with probable inflammatory cells were observed. Our results are consistent with the probability of positives as high as 0.1234 using a 95% confidence interval. CONCLUSIONS: The lack of EBS of the posterior ligament of the TMJ suggests that the role of estrogen contributing to internal derangement of the TMJ appears not to be significant.

Localization of CD44 and hyaluronan in the synovial membrane of the rat temporomandibular joint.

Previous studies have pointed out a lack of adhesion structures in the synovial lining layer of the rat temporomandibular joint (TMJ) despite showing an epithelial arrangement. CD44, a major cell adhesion molecule, plays crucial roles as an anchor between cells and extracellular matrices by binding hyaluronan (HA) for the development of organs or the metastasis of tumors. The present study examined the localization of CD44 in the synovial membrane of the rat TMJ by immunocytochemistry for OX50, ED1, and Hsp25, which are markers for the rat CD44, macrophage-like type A, and fibroblast-like type B synoviocytes, respectively. Histochemistry for HA-binding protein (HABP) was also employed for the detection of HA. OX50 immunoreactions were found along the cell surface and, in particular, accumulated along the surface of the articular cavity. Observations by a double immunostaining and immunoelectron microscopy revealed that all the OX50-immunopositive cells were categorized as fibroblastic type B cells, which had many caveolae and a few vesicles reactive to intense OX50. However, the macrophage-like type A cells did not have any OX50 immunoreaction in the synovial lining layer. A strong HABP reaction was discernable in the extracellular matrix surrounding both OX50-positive and -negative cells in the synovial lining layers, exhibiting a meshwork distribution, but weak in its sublining layer. This localization pattern of CD44 and HABP might be involved in the formation of the epithelial arrangement of the synovial lining layer. Furthermore, OX50 immunonegativity in the type A cells suggests their low phagocytotic activity in the rat TMJ under normal conditions.

Immunocytochemical localization of MAPKAPK-2 and Hsp25 in the rat temporomandibular joint.

One series of our research has shown an intense expression of immunoreaction for heat shock protein 25 (Hsp25) in various cellular elements in the rat temporomandibular joint (TMJ). This protein is the major substrate of mitogen-activated protein kinase-activated protein kinase-2 (MAPKAPK-2), which mediates an intracellular stress-activated signaling pathway to stimulate cytosolic actin reorganization under various stresses. The present study was undertaken to examine the localization of MAPKAPK-2 in the rat TMJ by immunocytochemical techniques. Furthermore, confocal microscopy with double staining was employed to demonstrate the colocalization of MAPKAPK-2 and Hsp25. Immunocytochemistry for MAPKAPK-2 showed an intense immunoreaction in the cytoplasm of the synovial lining cells, the endothelial cells, and the fibroblasts in the synovial membrane of the rat TMJ. Double immunostaining under a confocal microscope succeeded in demonstrating the colocalization of MAPKAPK-2 and Hsp25 immunoreactions in the cytoplasm of fibroblastic type B synoviocytes in the TMJ. On the other hand, the macrophage-like type A-cells expressed MAPKAPK-2 immunoreactions but lacked Hsp25 immunoreactivity. The cells in the articular disk and the chondrocytes in the maturative and hypertrophic layer of the mandibular cartilage also showed intense immunoreactions for MAPKAPK-2 and Hsp25. In addition to cytoplasmic localization, MAPKAPK-2 immunoreactions were found in the nucleus of some synovial lining cells, cells in the articular disk, and chondrocytes. Current observations imply the presence of the phosphorylation of Hsp25 via activated MAPKAPK-2 in the cytoplasm. MAPKAPK-2 and Hsp25 possibly participate in the induction of cytoskeletal changes to the various cellular elements in rat TMJ under normal conditions.

Soluble tumour necrosis factor receptors in synovial fluids from temporomandibular joints with painful anterior disc displacement without reduction and osteoarthritis.

The objective of this study was to detect soluble-form tumour necrosis factor receptors (sTNFRs) in temporomandibular joint (TMJ) synovial fluid aspirates, and to compare the sTNFR concentrations between painful anterior disc displacement without reduction and osteoarthritis (ADDwoR/OA) and asymptomatic TMJs. Synovial fluid was sampled from the superior TMJ cavity of 11 painful ADDwoR/OA cases (mean age: 36.9 years) and 10 asymptomatic females (mean age: 24.7 years) by diluted aspiration. The concentrations of sTNFR-I and -II in the synovial fluid were measured using human sTNFR-I and -II enzyme-linked immunosorbent assays. The total protein concentrations in synovial fluids were measured using a bicinchoninic acid protein assay kit. All data were normalised to the total protein concentration of each sample.Two-way factorial analysis of variance and post hoc multiple comparison revealed that: (1). mean normalised sTNFR-I and -II concentrations were higher in TMJ synovial aspirates from ADDwoR/OA patients than from healthy controls; (2). in the ADDwoR/OA patients and the healthy controls, the sTNFR-I concentration in TMJ synovial aspirates was higher than the sTNFR-II concentration; and (3). high TMJ synovial aspirate sTNFR-II seemed to be associated with less TMJ pain and a less restricted range of mouth opening in the ADDwoR/OA patients. The concentrations of sTNFRs in TMJ synovial fluid are higher in the presence of painful ADDwoR/OA, which could modulate intracapsular inflammation.

Prostaglandin E2 in temporomandibular joint synovial fluid and its relation to pain and inflammatory disorders.

PURPOSE: The aim of this study was to investigate temporomandibular joint (TMJ) synovial fluid (SF) levels of prostaglandin E2 and its relation to general inflammatory activity and its influence on specific TMJ pain in patients with inflammatory TMJ disorders. PATIENTS AND METHODS: The study comprised 24 patients (30 joints) with inflammatory TMJ disorders and 4 healthy persons (6 joints). TMJ pain at rest, tenderness to palpation of the TMJ, and TMJ pressure pain threshold, as well as pain during joint movements (PM), were assessed. PGE2 levels were analyzed in synovial fluid samples (SF-PGE2) and blood plasma (P-PGE2). The erythrocyte sedimentation rate (B-ESR) as well as the serum levels of C-reactive protein (S-CRP) and antinuclear antibodies were determined. RESULTS: PGE2 was undetectable in the plasma and in the TMJ SF of the healthy persons. In the patients, PGE2 was detectable in 20 of the 30 (67%) SF samples. SF-PGE2 was significantly and positively correlated to PM in the patients. There were significant correlations between P-PGE2 and B-ESR as well as the S-CRP. CONCLUSIONS: This study shows that the synovial fluid in patients with TMJ inflammatory disorders frequently has a detectable level of PGE2 that is related to TMJ allodynia. The plasma levels of PGE2 seem to be related to the general inflammatory activity in these patients.

Immunocytochemical demonstration of heat shock protein 25 in the rat temporomandibular joint.

The expression of heat shock protein 25 (Hsp 25) was investigated in the rat temporomandibular joint by immunocytochemistry combined with confocal and electron microscopy. Immunostaining with an antibody to Hsp25 was able to demonstrate various cellular elements in the synovial membrane of the joint. Intense immunoreaction for Hsp25 was recognized in certain cells comprising the synovial lining layer. Confocal microscopic observation revealed two characteristic profiles of the Hsp25-positive cells with cytoplasmic processes: one extended thick and long processes towards the articular cavity, and the other prejected horizontally slender processes which covered the synovial membrane. Under the electron microscope, the immunoreactive synovial lining cells were characterized by a well-developed rough endoplasmic reticulum and secretory granules, suggesting that they can be categorized as fibroblastic type B cells. The covering by the cytoplasmic extensions was confirmed by immuno-electron microscopic observations. This cytoplasmic covering presumably performs a barrier function and expedites the effective secretion/resorption of synovial fluids. Since it has been proposed that Hsp 25 is associated with an estrogen receptor, the immunopositive synovial lining cells were considered estrogen-target cells. Immunoreactivity for Hsp25 was also observed in the chondrocytes of the maturative and hypertrophic cell layers as well as in the cells of the articular disk. A suggestion was made that Hsp25 might be involved in the inhibition of apoptosis of those cells.

Intra-articular levels of prostaglandin E2, hyaluronic acid, and chondroitin-4 and -6 sulfates in the temporomandibular joint synovial fluid of patients with internal derangement.

PURPOSE: This study was conducted to measure the intra-articular levels of prostaglandin E2 (PGE2), hyaluronic acid, and chondroitin-4 and -6 sulfate in patients with temporomandibular joint (TMJ) internal derangement involving a closed lock, and to see if these levels correlate with the clinical or arthroscopic findings. PATIENTS AND METHODS: Fifteen female patients (16 joints) with a mean age of 36.7 years were diagnosed as having a closed lock by clinical examination and diagnostic MR imaging. The patient's subjective pain was assessed by a visual analog scale (VAS) and a pain questionnaire (pain score), and the interincisal opening was measured. TMJ aspirates were obtained by washing of the joint with saline containing vitamin B12 as a marker for calibration of data. The samples were assayed for PGE2 with a radioimmunoassay, and the concentrations of unsaturated disaccaride isomers of hyaluronic acid (delta di-HA), chondroitin-4 sulfate (delta di-4S), and chondroitin-6 sulfate (delta di-6S) were measured by high-performance liquid chromatography. Immediately after collection of the synovial aspirates, diagnostic arthroscopy was performed on all but three joints to evaluate the severity of synovitis and cartilage degeneration. The degree of arthroscopic pathology was scored quantitatively. Intra-articular levels of PGE2, delta di-HA(HA), delta di-4S(C4S), and delta di-6S(C6S) were compared with patient's age, mouth opening, VAS rating, pain scores, and arthroscopic scores for synovitis and cartilage degeneration. RESULTS: The PGE2 level did not correlate with the clinical or arthroscopic parameters. HA had a weak correlation with mouth opening (0.54). C4S and C6S were correlated with arthroscopic scores of TMJ degeneration (0.97, 0.89) and with age (0.75, 0.62). The ratio of C4S and C6S to HA was also correlated with the arthroscopic indices of degeneration (0.93, 0.8) and PGE2 level (0.74, 0.69), but not with age. CONCLUSION: The PGE2 level in the TMJ synovial fluid does not specifically reflect the intensity of pain or synovitis, but the detection of high concentrations of C4S and C6S, compared with the amount of HA, is a possible marker of proteoglycan degradation in the TMJ.

Measurement of joint aspirate dilution by a spectrophotometer capillary tube system.

The amount of synovial fluid in small joints which is available for analysis of endogenous compounds is usually very limited and saline washings are therefore commonly required. However, since the washing fluid is not fully recovered and, furthermore, dilutes the synovial fluid in the joint aspirate, the true synovial fluid concentration of a particular substance is unknown. In the present study we validate the use of vitamin B12 (hydroxocobalamin, 1 mg ml-1) as an internal standard to determine this dilution, since its strong red colour lends itself to spectroscopic measurement by a capillary tube system requiring only 3 microliter per sample. The absorbance of different dilutions of the stock solutions (25, 33 and 50% vitamin B12 in saline) by saline, plasma and hyaluronan was measured in order to establish the optimal wavelength, the lower limit of detection and the interference by plasma or hyaluronan in the absorbance. Furthermore, the interaction of vitamin B12 in the analyses of interleukin-1 beta, serotonin and glucose was investigated. The optimal wavelength was found to be 350 nm and the limit of detection 0.5-0.9% dilution of the vitamin B12 solution. Hyaluronan or plasma did not influence the absorbance measurements and the minute interaction of vitamin B12 in the photometric measurements could be compensated for.

Effects of sex hormones on protein and collagen content of the temporomandibular joint disc of the rat.

PURPOSE: The effect of sex hormones on the protein and collagen content of the temporomandibular joint (TMJ) disc of adult male and female rats. MATERIALS AND METHODS: One hundred forty-four Wistar rats were assigned to 14 groups of 12 each. Two groups, one female and one male, served as a control and received no treatment, and two other groups (one female and one male) received a sham gonadectomy and placebo hormone. The remaining 10 groups (five males and five females) received either orchiectomy or ovariectomy, followed by administration of estrogen, progesterone, combined estrogen and progesterone, or testosterone. The total protein and collagen content of the TMJ disc were determined using the calorimetric hydroxyproline method. RESULTS: The collagen content of TMJ discs of control males was statistically greater than the collagen content of the control female rats. This difference disappeared after ovariectomy of females and orchiectomy of males. Also, there was a general trend for a decrease in collagen and protein content to be produced by estrogen, progesterone, and by estrogen combined with progesterone in castrated male and female rats, and by orchiectomy of male rats. There was also a trend toward an increase in collagen and protein content after ovariectomy in female rats and administration of testosterone to castrated male and female rats. However, the only statistically significant effect of the drugs tested was that of estrogen combined with progesterone in ovariectomized female rats (a lowering effect on the total protein) and of estrogen alone in orchiectomized male rats (a lowering effect on the collagen content). CONCLUSION: Steroid sex hormones have an effect on the collagen and protein content of the TMJ disc of the rat as indicated by the difference in the values between control males and females and by the disappearance of this difference on castration of both male and female animals. This was also manifested by the significant effect of estradiol on collagen content of castrated males, by the effect of estrogen combined with progesterone on the protein content of castrated females.

Endoarticular loose bodies and calcifications of the disk of the temporomandibular joint: morphological features and chemical composition.

We studied articular disks and endoarticular loose bodies taken from patients suffering from different types of temporomandibular joint (TMJ) pathology. The scanning electron microscopy (SEM) analysis of the disks and the endoarticular loose bodies was followed by a chemical-compositional analysis using an energy dispersive spectrometer (EDS) and by characterization of the crystalline phases by X-ray powder diffraction (XRD). The articular disks were composed of a central radiopaque area lacking any evident structural features, surrounded by compact bundles of collagen fibers. EDS and XRD analyses showed that endodiscal radio-opaque areas were hydroxyapatite. By SEM, we observed a fibrous network only in circumscribed areas of the endoarticular loose bodies. The chemical-compositional analysis showed that the loose bodies were composed of calcite (CaCO3). The results of this investigation, along with the clinical history of the patients, allow us to formulate some hypotheses regarding the etiopathogenesis of these structural anomalies. The endodiscal calcifications could be the result of a chronic inflammatory process that produces displastic alterations of the articular disk. Moreover, an acute inflammatory process with modifications in the mechanisms of the synovial fluid turnover seems to be the event that leads to the formation of endoarticular loose bodies.

Efecto del factor de crecimiento insulinico (IGF-1) sobre condrocitos de la articulacion temporomandibular de cerdos in vitro / Condrocytes in vitro cultures of temporomandibular joint executed in a pig fetus

El presente trabajo de investigación realizado en el laboratorio de cultivos celulares del Instituto Colombiano Agropecuario "ICA", reporta los resultados preliminares de un cultivo in vitro de condrocitos de articulación temporomandibular (ATM) de fetos de cerdo, informando los pasos empleados en la técnica de una manera detallada y depurada, para la obtención de dichas células. El objetivo general de la línea era el de lograr, una vez cultivados los condrocitos, aplicar el factor de crecimiento insulínico-1 (IGF-1) al cultivo in vitro y evaluar su crecimiento y viabilidad celular, con el fín de poder aplicar posteriormente dicho factor in vivo, lo cual sería tema de un nuevo proyecto. La literatura desde mediados del siglo xx reporta interesantes investigaciones como las de Takigawa, Demarkay y otros, quienes con base en cultivos celulares de diferentes sitios y de diferentes animales demostraron la posibilidad de mantener dichas células vivas. El trabajo guía, y al cual se le realizaron algunas modificaciones fué el cultivo a gran escala de condrocitos, consignado por Klagsbrun en el Libro de Jakobi en 1979. En el informe preliminar que se presenta, se reportan todas las complicaciones y problemas que surgieron a lo largo de 21 cultivos. De los cuales siete de ellos presentaron resultados positivos como viabilidad y no contaminación superior a las 24 horas. Debido a la dificultad de mantener las células adheridas a los frascos de cultivo y a las láminas de microscopio, no fué posible realizar tinciones ni microfotografías

Experimental temporomandibular joint disc perforation in the rabbit: a gross morphologic, biochemical, and ultrastructural analysis.

This study evaluates the progression of osteoarthritis (OA) in the adult New Zealand white rabbit temporomandibular joint following unilateral disc perforation. Thirty-seven animals were divided into five groups: control (n = 8), 6-week sham (n = 5), and experimental 6-, 12-, and 24-weeks (n = 8 each). Quantitative data was examined with two-way analysis of variance, and followed by Scheffe pair-wise comparisons. Transmission electron microscopy, acid phosphatase [AcP] activity, uronic acid content, and gross morphologic analysis indicated that disc perforation induced remodeling activity and degenerative changes in the condylar cartilage and bone as early as 6 weeks postoperatively. AcP activity of homogenized cartilage samples was significantly increased in experimental joints versus the side that did not undergo surgery at 6 and 12 weeks (P < .05). Uronic acid content was significantly greater in experimental joints versus the side that did not undergo surgery at 6 weeks (P < .05). Heightened cellular activity was present in the deep zone of osteoarthritic fibrocartilage of the 6- and 12-week experimental groups. Degenerating chondrocytes appeared to contain greater proportions of intracytoplasmic filaments and lysosome-like bodies. Disc perforation provided the impetus for degenerative or remodeling changes in the condylar cartilage of experimental joints, and is consistent with secondary OA. These dynamic events were most significant in the deep zone of articular fibrocartilage.

Temporomandibular joint synovial fluid analysis.

A method for the estimation of the synovial fluid volume of the temporomandibular joint (TMJ) is described. Patients are administered 1.2 g of aspirin and the concentration of salicylate in plasma and in saline aspirates of the TMJ is measured by a sensitive high performance liquid chromatography assay. The ratio of the concentration of salicylate in the saline aspirate to that in the plasma allows the volume of the synovial fluid to be calculated. The method would also allow the determination of the concentration and the absolute amount of putative mediators of pathology in the upper joint.