Condylar Articular Surface Research Articles

Effects of food hardness on temporomandibular joint osteoarthritis: Qualitative and quantitative micro-CT analysis of rats in vivo

BackgroundTemporomandibular joint osteoarthritis (TMJ-OA) is a degenerative joint disease in which quantitative analysis based on magnetic resonance image (MRI) or cone-beam computed tomography (CBCT) remains limited. Moreover, the long-term effects of soft food on the adaptive condylar remodeling process in TMJ-OA remain unclear. This study aimed to assess the effects of food hardness on adaptive condylar remodeling in a healthy TMJ, TMJ-OA, and controlled TMJ-OA. MethodsComplete Freund’s adjuvant (CFA) was used for TMJ-OA induction and Link-N (LN) for TMJ repair. Eighteen mature rats were randomly divided into six groups: (1) control/normal diet (Ctrl-N); (2) control/soft diet (Ctrl-S); (3) TMJ-OA/normal diet (CFA-N); (4) TMJ-OA/soft diet (CFA-S); (5) Link-N-controlled TMJ-OA/normal diet (LN-N); and (6) Link-N-controlled TMJ-OA/soft diet (LN-S). Micro-CT was performed 14, 21, and 28 days after CFA injection to analyze the bone volume, bone volume fraction (BVF), bone mineral density (BMD), and trabecular bone number and thickness (Tb.N, Tb.Th). MRI and histological imaging were performed to support the analysis. ResultsUnder CFA treatment, the BVF and BMD decreased significantly (p < 0.01) and later recovered to normal. However, more significant improvements occurred in normal-diet groups than soft-diet groups. Additionally, bone volume changes were more predictable in the normal-diet groups than in the soft-diet groups. The normal-diet groups presented a significant decrease and increase in the Tb.N and Tb.Th, respectively (p < 0.05), while the Tb.N and Tb.Th in the soft-diet groups remained largely unchanged. Furthermore, a significantly higher frequency of irregularities on the condylar articular surface was found in the soft-diet groups. ConclusionsCompared with a soft diet, a normal diet may be beneficial for preserving condyle articular surface and directing bone remodeling in TMJ-OA rats.

Repair of experimentally induced femoral chondral defect in a rabbit model using Lyophilized growth promoting factor extracted from horse blood platelets (L-GFequina)

Lyophilized equine platelet derived growth factors (LGF) is a novel advanced platelet rich protein growth factor. It has been successfully applied in various fields of regenerative medicine to treat a variety of inflammatory and degenerative musculoskeletal conditions. Our study aimed to evaluate the efficacy of intraarticularly injected LGF for the remedy of articular cartilage injury, commonly characterized by progressive pain and loss of joint function in osteoarthritic rabbits. Full-thickness cylindrical cartilage defects were generated in both femoral condylar articular surfaces in twenty rabbits. The left joint of all animals was injected with the adjuvant as a self-control negative, while the right joint was injected by LGF. Four- and eight-weeks post-surgery, the femoral condyles were harvested, and assessed grossly, microscopically and immunohistochemically. Cytokines (TNF-α, IL-1β, PDGF and TGF-β1) contents of the chondral defects were quantified by ELISA as well as the gene expression of Col I and Col II via RT-qPCR. The LGF treated defects showed significant higher ICRS (International cartilage repair society) healing scores of cartilaginous regeneration with a significant higher histological healing score on using O'Driscoll histological scoring system. Additionally, LGF significantly lowered the levels of the pro-inflammatory cytokines TNF-α and IL-1β. It also significantly increased the anabolic and angiogenic growth factors (PDGF and TGF-β1), and significantly elevated the expression of chondrogenic-related marker genes; Col I and Col II. The current study reveals that LGF improves chondral healing and thus it can be a superior nominee as an adjunctive therapy to positively influence regeneration of chondral defects in osteoarthritic patients.

Digital radiographic measurement of tibial and femoral condylar articular surface asymmetry and knee joint space

Introduction: Knee joint is a major weight bearing synovial joint. In frontal radiograph we can see asymmetrical joint spaces between femoral and tibial components due to asymmetric wear and tear. Articular surfaces of tibial and femoral condyles are also asymmetrical. In frontal radiograph, the tibial condylar articular surface can be seen projected outside laterally or medially with respect to lateral or medial femoral condyle. Objectives: To measure tibial and femoral articular surface asymmetry. Measurement of tibial and femoral joint space. Materials and Methods: This epidemiological study was conducted in Orthopaedic outpatient department (OPD) of Ramakrishna Mission Seva Pratishthan Kolkata. Total 350 patients were selected. Frontal standing radiograph of both knees with 100% magnification were obtained. Tibial condylar asymmetry and joint spaces were measured with calliper. Height and weight measurements were also done. Statistical analysis was done. Results: In right knee 96% patients lateral tibial condyle was projected outside with respect to femoral condyle. In 9.3% patients’ medial tibial condyle was outside. In left knee 92.6% patients lateral tibial condyle was outside and 15.7% patients’ medial tibial condyle was outside. In right knee lateral joint space was mean + sd= 4.45 + 1.06, medial joint space mean + sd= 1.70 + 94. In left knee lateral joint space was mean + sd= 4.59 + 1.00, medial joint space was mean + sd= 1.76 + 1.00. Conclusion: In this study, in most of the patients we found tibial and femoral articular surface asymmetry mainly in lateral side. In joint space measurement, we found that medial joint space was less than lateral joint space in both knees.

Initial radiological signs of dentofacial deformity in juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is the most common rheumatic disease in childhood and the temporomandibular joint (TMJ) is often involved. TMJ arthritis in growing individuals can cause deformation of facial skeleton (dentofacial deformity) and TMJ components (TMJ deformity). Treatment outcome hinges on early initiation of anti-inflammatory treatment and orthopaedic treatment with dental splints. The aim of the present study was to characterize the radiological signs of dentofacial deformity in patients with a JIA-induced need for orthopaedic treatment. We retrospectively studied 96 patients with JIA and 20 non-JIA controls to identify the initial radiological signs of JIA-induced dentofacial deformity leading to initiation of orthopaedic treatment. We found that initial radiological signs of dentofacial deformities were subtle and characterized by minor mandibular asymmetry and occlusal plane steepening. Radiological findings of TMJ deformity associated with initial dentofacial deformity were frequent and characterized by condylar articular surface flattening (OR 8.42), condylar subcortical cyst (OR 5.94), condylar surface erosion (OR 5.38) and condylar deviation in form (OR 25.39). Radiological signs of TMJ deformity were also documented in TMJs considered “healthy” during initial clinical and radiological examination. This study presents new knowledge of importance for early diagnosis of dentofacial deformity in JIA. Early diagnosis of dentofacial deformity is important as treatment outcome is greatly influenced by timely initiation.

Extracapsular Condylar Fractures Treated Conservatively in Children: Mechanism of Bone Remodelling.

This study aims to reveal the reconstruction process in pediatric patients with extracapsular condylar fractures after conservative treatment. We clarify that the "upright" position (or "recontouring" or favorable prognosis) of condyles is not a result of the anatomical reduction of the deviated condylar processes but originates from the remodeling of the skeleton. We also explore the related mechanism. The sample consisted of 27 pediatric patients aged less than 12 years who presented with extracapsular condylar fractures and were treated conservatively within an 8-year period (June 2011-April 2019). Data on the age, gender, date of injury, mechanism of trauma, location and pattern of mandibular condylar fracture and associated injuries and treatment methods of the patients were obtained. The process of bone remodeling in condyles was also recorded and analyzed. The 27 children in this study sustained 33 extracapsular condylar fractures over the 8-year period of record retrieval. Amongst these fractures, 8 (24.2%) and 25 (75.8%) were condylar neck and condylar base fractures, respectively. Deviation and green-stick fractures were the predominant types and accounted for over 3 quarters of the condylar neck and base fractures (28, 84.8%), followed by dislocation fracture (3, 9.1%), displacement fracture (1, 3.0%), and non-displaced fracture (1, 3.0%). The period of follow-up ranged from 2 days to 257 days (average, 58.78 days). Only 1 patient with bilateral extracapsular condylar fractures showed vertically reconstructed condyles, which indicates an upright position of the condylar processes. One patient showed less angulation after treatment than before treatment, 1 patient revealed greater angulation after treatment than before treatment and all other patients (20 patients) showed the same angulation pre- and post-treatment. Both patients with only extracapsular condylar fractures showed no obvious deviations in dentition and facial asymmetry after their injury and treatment. The shortest and longest times observed for bone remodeling were 33 and 256 days, respectively. Children whose condylar head remained completely or at least partly inside the glenoid fossa showed satisfactory remodeling results during follow-up. Computed tomography scan during follow-up generally showed bone regeneration in the lateral condyle articular surface and the medial portion of the ascending ramus and bone resorption in the displaced direction (ie, the medial condyle head became sharp). Condylar heads displaced completely outside of the glenoid fossa showed serious shortening of the ascending ramus, and no obvious bone remodeling was observed. Only 1 patient with bilateral extracapsular condylar fractures showed a normal contour (ie, a vertically reconstructed condyle reflecting the upright position of the condylar processes) after 8 months. Stress stimulation originating from the glenoid fossa and ascending ramus of the mandible is a prerequisite for good condylar reconstruction. Conservative treatment could be carried out if the condylar head remains completely or at least partly inside the glenoid fossa. When the condylar head is dislocated completely outside the glenoid fossa, the glenoid-condylar relationship ceases to exist, joint function is lost and the height of the ascending ramus is significantly reduced. In this case, open reduction may be suitable.

3D Auto-Segmentation of Mandibular Condyles.

Temporomandibular joints (TMJ) like a hinge connect the jawbone to the skull. TMJ disorders could cause pain in the jaw joint and the muscles controlling jaw movement. However, the disease cannot be diagnosed until it becomes symptomatic. It has been shown that bone resorption at the condyle articular surface is already evident at initial diagnosis of TMJ Osteoarthritis (OA). Therefore, analyzing the bone structure will facilitate the disease diagnosis. The important step towards this analysis is the condyle segmentation. This article deals with a method to automatically segment the temporomandibular joint condyle out of cone beam CT (CBCT) scans. In the proposed method we denoise images and apply 3D active contour and morphological operations to segment the condyle. The experimental results show that the proposed method yields the Dice score of 0.9461 with the standards deviation of 0.0888 when it is applied on CBCT images of 95 patients. This segmentation will allow large datasets to be analyzed more efficiently towards data sciences and machine learning approaches for disease classification.

Technique for Treatment of Subchondral Compression Fracture of the Lateral Femoral Condyle Associated With ACL Tear

Excessive knee pivoting that causes a complete anterior cruciate ligament (ACL) tear may result in a subchondral compression fracture on the lateral femoral condyle after impacting the lateral tibial condyle. Because this mechanism is similar to the humeral head that has an impact on the glenoid during an anterior shoulder dislocation, such an osteochondral fracture can be considered equivalent to a “Hill-Sachs lesion of the knee.” Restoring the native anatomy of the lateral femoral condyle articular surface is crucial, because its depression alters knee biomechanics, leading to bony knee instability, potentially greatly elevating the risk of ACL reconstruction failure and meniscal tears. In addition, bony knee instability increases the forces acting on the cartilage, which may impair one's quality of life and lead to the development of osteoarthritis. The fact that many patients with complete ACL tears are relatively young emphasizes the key role of osteoarthritis prevention. The aim of this report is to present a minimally invasive procedure to treat the “Hill-Sachs–like” knee lesion, a tricky enemy of knee stability.

The relationship between the posterior tibial slope and the sagittal femoral condylar shape: Two circles and ellipses.

Whether the posterior tibial slope (PTS) is associated with the femoral condylar shape has remained unclear. Classical anatomical studies considered the sagittal profiles of femoral condyles to consist of two circles. Recently, an elliptical method was described to simplify the "two circles" model. Our purpose was to analyze the relationship between the PTS and the shape of the sagittal femoral condyle, that is, two circles and two ellipses, using magnetic resonance imaging (MRI) scans. Eighty right knees of healthy subjects were scanned by MRI at full extension. The medial and lateral PTS were measured (mPTS and lPTS). On the distal-most medial and lateral slices, the femoral condylar articular surfaces were best fitted by circles or ellipses, respectively. The radii of the medial and lateral posterior circles and inferior circles (rm and rl , Rm and Rl , respectively), the semi-major axes and the semi-minor axes of the medial and lateral ellipses (am and al , bm and bl , respectively), and the rm /Rm , bm /am , rl /Rl , bl /al ratios were measured and calculated. mPTS correlated significantly with the parameters of the medial condyle (all p < .05) and the ratios bm /am and rm /Rm (p = .017 and p = .027, respectively). However, the lPTS did not correlate with the parameters of the lateral condyle (all p > .05) or the ratios bl /al and rl /Rl (p = .461 and p = .241, respectively). The mPTS is associated with the sagittal shape of the medial femoral condyle but the lPTS is not. Both two circles and two ellipses are feasible ways to represent the sagittal femoral condylar shape.

Internal architecture of the mandibular condyle of rabbits is related to dietary resistance during growth.

Although there is considerable evidence that bone responds to the loading environment in which it develops, few analyses have examined phenotypic plasticity or bone functional adaptation in the masticatory apparatus. Prior work suggests that masticatory morphology is sensitive to differences in food mechanical properties during development; however, the importance of the timing/duration of loading and variation in naturalistic diets is less clear. Here, we examined microstructural and macrostructural differences in the mandibular condyle in four groups of white rabbits (Oryctolagus cuniculus) raised for a year on diets that varied in mechanical properties and timing of the introduction of mechanically challenging foods, simulating seasonal variation in diet. We employed sliding semilandmarks to locate multiple volumes of interest deep to the mandibular condyle articular surface, and compared bone volume fraction, trabecular thickness and spacing, and condylar size/shape among experimental groups. The results reveal a shared pattern of bony architecture across the articular surface of all treatment groups, while also demonstrating significant among-group differences. Rabbits raised on mechanically challenging diets have significantly increased bone volume fraction relative to controls fed a less challenging diet. The post-weaning timing of the introduction of mechanically challenging foods also influences architectural properties, suggesting that bone plasticity can extend well into adulthood and that bony responses to changes in loading may be rapid. These findings demonstrate that bony architecture of the mandibular condyle in rabbits responds to variation in mechanical loading during an organism's lifetime and has the potential to track dietary variation within and among species.

TEMPOROMANDIBULAR CONDYLAR OSTEOCHONDROMAS: CHARACTERISTICS AND COMPLICATIONS

<h3>Background</h3> Benign, solitary osteochondromas arise in response to an event (e.g., trauma, x-radiation), rather than as true neoplasms. Typically, osteochondromas represent 10% to 15% of all bone tumors and approximately 35% of benign bone tumors. They usually develop during a known age range and at largely predictable anatomic sites, whether the osteochondroma is benign or malignant. The most important piece of clinical information is the patient's age, although exceptions exist. Most osteochondromas occur on the metaphysis of appendicular long bones. <h3>Clinical and Radiographic findings</h3> Three cases are of temporomandibular condylar osteochondromas are presented. All patients were adult males with ages 29, 55, and 56 years. Each tumor arose from the condylar articular surface and developed into abnormal morphologies that followed the outline of adjacent structures. <h3>Definitive Interpretation</h3> The radiographic findings of an exostotic bony tumor with smooth but irregular outlines, sclerosed cortices, and moderately dense trabeculation confined within the joint capsule were consistent with the radiographic appearance of osteochondroma. <h3>Discussion</h3> Radiographically, 2-D imaging is adequate to establish an initial radiographic diagnosis. However, more advanced modalities (computed tomography/magnetic resonance imaging [CT/MRI) are indicated to better evaluate the orientation of the tumor and assist in the surgical management. The 3-D imaging of the 3 cases presented here emphasize this point. Positron emission tomography/fluorodeoxyglucose (PET/FDG) imaging has also been recommended for specific cases. MRI may overestimate tumor aggressiveness secondary to the influence of bone marrow and soft tissue edema. The recognition of an osteochondroma is significant because it is benign, but it can lead to disfigurement and loss or altered mandibular function, if not treated.

Low-intensity pulsed ultrasound repair in mandibular condylar cartilage injury rabbit model

ObjectivesBeneficial effects of low-intensity pulsed ultrasound(US) have been reported for knee articular cartilage injury. It is unclear whether the same effect could be observed on mandibular condylar cartilage. This study was designed to explore the efficacy of ultrasound cartilage repair via autophagy regulation. MethodsA total of 18 adult rabbits were divided into a sham operation group (exposure to condylar articular surface only), operation without US group (only cartilage surgery), and operation with US group (received ultrasonic therapy daily on day 4 after cartilage surgery). The rabbits were then sacrificed to construct a temporomandibular joint (TMJ) cartilage injury model and HE staining was conducted to observe pathological changes of cartilage in each group. Expression of FGF18, FGFR4, beclin1, ATG3 and ATG7 in rabbit TMJ cartilage were detected using RT-PCR and western blotting. Finally, protein-protein interaction (PPI) analysis was used to observe the interaction among the network of important biomarkers in this injury model. ResultsCompared to the operation without US group, the severity of cartilage injury was decreased in the operation with US group according to HE staining. The expression of autophagy biomarkers, beclin1, ATG3, ATG7, FGF18 and FGFR4, in operation with US group were up-regulated compared with those in sham operation group and operation without US group p < 0.05). In PPI analysis, ATG3, ATG7, PIK3C3, PIK3R4, BECN1 were identified as hub nodes connecting with most proteins network. ConclusionsOur results suggest US has therapeutic potential for the treatment of mandibular condylar cartilage injury, and may affect chondrocyte autophagy.

Restoring Condylar Width: Radiographic Relationship Between the Lateral Tibial Plateau and Lateral Femoral Condyle in Normal Adult Knees.

We hypothesized that a constant radiographic relationship exists between the lateral tibial and femoral condyles and that no side-to-side variation exists. We reviewed anteroposterior x-rays of 217 uninjured adults ages 18-65, Included 109 unilateral and 108 bilateral radiographs with no or minimal osteoarthrosis (Kellgren-Lawrence grades 0-1). The perpendicular distance between the lateral-most margins of the tibial plateau articular surface (A) and the lateral femoral epicondyle (B) and the lateral femoral condyle articular surface (C) was measured in millimeters (mm). Medial and lateral measurements to point (A) were recorded as (-) and (+), respectively. First, the average of measured distances in all unilateral knees and randomly selected either right or left knees from the bilateral group (n = 217) was calculated. Comparison was made between both sexes. Next, A-B and A-C distances were compared between right and left knees in the bilateral group (n = 108) to find any significant difference (2-tailed t test, alpha = 0.05). The average A-B distance was 0.60 ± 2.40 mm (-4.82 to +6.49 mm). The mean A-C distance was -3.96 ± 2.07 mm (-8.51 to +3.98 mm). No significant difference was found between A-B and A-C distances between males (0.40 ± 2.62 mm and -3.91 ± 2.05 mm) and females (0.70 ± 2.28 mm and -3.99 ± 2.09 mm). Similarly, no significant difference was found between A-B and A-C distances between right (1.08 ± 2.31 mm and -3.90 ± 1.73 mm) and left knees (0.90 ± 2.38 mm and -4.31 ± 1.7 mm). Concordance coefficient for interobserver and intraobserver reliability showed substantial agreement. In conclusion, this study provided a "normal" range for the relationship of the proximal lateral tibial plateau relative to the lateral femoral condyle. The lateral femoral epicondyle is generally aligned with the lateral tibial articular margin. The relationship between the lateral tibial plateau, lateral femoral epicondylar surface, and lateral femoral articular surface is constant from side to side. This technique is reproducible in the setting of fracture, and templating off of the contralateral uninjured knee may be beneficial in tibial plateau fracture surgery.

Part I: Development and Physiology of the Temporomandibular Joint.

Investigate the developmental physiology of the temporomandibular joint (TMJ), a unique articulation between the cranium and the mandible. Principal regulatory factors for TMJ and disc development are Indian hedgehog (IHH) and bone morphogenetic protein (BMP-2). The mechanism is closely associated with ear morphogenesis. Secondary condylar cartilage emerges as a subperiosteal blastema on the medial surface of the posterior mandible. The condylar articular surface is immunoreactive for tenascin-C, so it is a modified fibrous periosteum with an underlying proliferative zone (cambrium layer) that differentiates into fibrocartilage. The latter cushions high loads and subsequently produces endochondral bone. The TMJ is a heavily loaded joint with three cushioning layers of fibrocartilage in the disc, as well as in subarticular zones in the fossa and mandibular condyle. The periosteal articular surface produces fibrocartilage to resist heavy loads, and has unique healing and adaptive properties for maintaining life support functions under adverse environmental conditions.

Is Lateral Femoral Notch Depth Associated with Rotatory Instability in ACL Deficient Knees: A Quantitative Pivot Shift Analysis

Objectives:Persistent rotatory knee instability after anterior cruciate ligament (ACL) reconstruction is relatively common. While the causes of this persistent instability are multifactorial, bony morphologic characteristics have been proposed to play a role. Therefore, the purpose of this study was to evaluate the relationship between the well-described lateral femoral notch (LFN) depth and quantitative measures of rotatory knee stability. We hypothesized that greater LFN depth would be associated with increased rotatory knee instability.Methods:A consecutive series of patients undergoing primary ACL reconstruction at our university medical center from June 2014 to April 2016 were analyzed. Inclusion criteria included primary ACL tear, no concurrent ligamentous or bony injury requiring operative treatment, no history of previous knee injury or surgery to the ACL-injured extremity, and no history of injury or surgery to the contralateral knee. A standardized pivot shift test was performed by the senior surgeon preoperatively under anesthesia in both knees and quantified using tablet image analysis software and accelerometer sensors as previously described and validated. Lateral knee radiographs and sagittal magnetic resonance images (MRI) of the injured knee were evaluated for depth of the LFN as previously described. A line tangent to the lateral femoral condyle articular surface was drawn across the notch. Notch depth was measured perpendicular from this line to the deepest point of the LFN. Pearson correlation coefficient was used to analyze correlations between continuous variables. Chi-square test was used to analyze relationships between notch depth and presence/absence of medial or lateral meniscus tears. Analyses were performed with SPSS 22.0 and significance was set at a p<0.05.Results:Fifty patients met inclusion criteria and were included in this study (mean age 24 years, range 13-45; 28 females, 22 males). Mean LFN depth as measured via x-ray was 0.8 mm (SD=0.63, n=50) and via MRI was 1.0 mm (SD=0.73, n=47). Twenty-two (44%) patients had a medial meniscus tear and 27 (54%) had a lateral meniscus tear. LFN on x-ray had moderate but significant positive correlations with ipsilateral lateral compartment acceleration (r=0.402, p=0.004) and acceleration side-to-side differences (r=0.407, p=0.003). LFN depth on MRI had moderate but significant positive correlations with ipsilateral lateral compartment acceleration (r=0.334, p=0.022) and acceleration side-to-side differences (r=0.363, p=0.012). LFN depth on x-ray was significantly associated with the presence of a lateral meniscus tear (p=0.014). There were no significant associations between LFN depth (x-ray or MRI) on ipsilateral or contralateral lateral compartment translation, contralateral lateral compartment acceleration, or the presence of medial meniscus tears.Conclusion:The results from this study demonstrated that a well described bony morphologic feature - LFN depth - was correlated with higher lateral compartment acceleration as measured by quantitative pivot shift analysis. Furthermore, greater LFN depth was associated with an increased incidence of lateral meniscus tears, which supports findings from previous studies. Assessment of LFN depth may help clinicians identify patients with greater rotatory instability prior to ACL reconstruction and potentially direct surgical treatment to account for additional rotatory knee instability.Table 1: Mean Quantitative Pivot Shift Values of the Injured and Uninjured KneeInjuredUninjuredSide-to-Side DifferenceCompartment Acceleration (m/s2)5.14 (SD=0.73)3.45 (SD=0.95)1.68 (SD=2.09)Lateral Compartment Translation (mm)3.67 (SD=2.30)1.22 (SD=0.75)2.46 (SD=2.24)

Computed tomographic study of the patterns of oesteoarthritic change which occur on the mandibular condyle

The aim of this study was to investigate which parts of the articular surface of the mandibular condyle are involved in osteoarthritic (OA) change (the occurring pattern) and the relationship of these patterns to clinical signs and symptoms. The computed tomographic (CT) images and clinical records of patients with OA involvement of one or both of their temporomandibular joints (TMJs) were reviewed (OA changes confirmed by CT; 684 TMJs included). The condylar articular surface was divided into nine imaginary sections on the CT images: antero-medial (AM), antero-central (AC), antero-lateral (AL), centri-medial (CM), centri-central (CC), centri-lateral (CL), postero-medial (PM), postero-central (PC), and postero-lateral (PL) section. The occurring patterns were classified with hierarchical cluster analysis based on the distribution of the sections involved by OA changes. OA changes were observed the most frequently on the AC (62.4%) followed by the AM (55.0%), CC (48.2%), AL (43.0%), CL (43.3%), CM (33.3%), PC (28.9%), PL (25.3%), and PM (23.1%). The occurring patterns were classified into three types among which subjective joint pain (P < 0.001) and noise (P < 0.05) were more frequently reported in the entire-involved type followed by lateral- and antero-medial types in descending order, while no significant differences for age, gender, side, pain on palpation, clicking, crepitus, mouth opening range and craniomandibular index were observed. OA changes are more likely to occur on the anterior than the posterior and on the medial than the lateral surface of the mandibular condyle, while subjective joint pain and noise are more frequently reported with OA changes involving the lateral or entire part. Pain on palpation, noise, and mouth opening range were not related to the occurring pattern of OA changes.

A New Crown-Group Salamander from the Early Cretaceous of Western Siberia

Kiyatriton leshchinskiyi gen. & sp. nov. is based on the atlas centrum and incomplete femora from the Lower Cretaceous (Aptian-Albian) Ilek Formation at Shestakovo 1, Kemerovo region, Western Siberia, Russia It is referred to the crown-group salamanders (Urodela incertae sedis ) because of presence of enclosed spinal nerve foramina in the atlas. The new taxon is distinctive in the moderately dorsoventrally compressed anterior cotylar surfaces and unique tripartite division of the posterior condyle articular surface on the atlas. It is the first «lissamphibian» discovered from the Mesozoic of Siberia.

Subarticular, cystlike lesion associated with avascular necrosis of the mandibular condyle: a case report

Little is known about avascular necrosis of the mandibular condyle, which is necrosis of the epiphyseal or subarticular bone secondary to a diminished or disrupted blood supply in the absence of infection. We present a case of a large subarticular cystlike lesion that was found using cone-beam computed tomography (CBCT). There was an absence of osteoarthrosis, and the condylar articular surface was relatively intact. The patient's history, physical examination, and magnetic resonance images supported the diagnosis of avascular necrosis of the mandibular condyle. After 4 months of conservative therapy, new bone was observed in the cystlike marrow lesion, and a smooth articular surface was reestablished. Subarticular cystlike lesions without the collapse of the articular surface of mandibular condyles may be an early indicator of avascular necrosis.

Condylar cartilaginous changes after mandibular distraction osteogenesis in rabbits

The purpose of this study was to evaluate histologic and immunohistochemical changes in the condylar articular surface in response to distraction osteogenesis (DO) of the mandibular body in rabbits. A unilateral osteotomy of the mandible at the premolar area was performed in 16 rabbits. The animals were divided into 4 groups based on different distraction parameters (rate and rhythm). After a 5-day latency, the mandible was lengthened by 0.5 mm daily for 6 days (group 1); 0.5 mm twice daily for 3 days (group 2); 0.5 mm once daily for 10 days (group 3); or 0.5 mm twice daily for 5 days (group 4). All 4 groups underwent a 14-day consolidation period. Four rabbits were included in the control group. The specimens were stained with hematoxylin-eosin for histologic examination. Immunohistochemical analysis was performed to evaluate the expression of growth factors. None of the groups demonstrated any degenerative changes in the temporomandibular joint (TMJ). On the distraction side in all groups, the histopathological examination revealed a hypertrophic thickening of the cartilage zone. Prominent endochondral ossification and high active osteoblasts were observed in groups 3 and 4. On the nondistraction side, no major changes were observed excluding the appearance of osteoclasts in groups 3 and 4. The immunohistochemical analysis revealed tenascin immunoreactivity in bone marrow mesenchymal cells on the distraction side in group 4. Connexin immunoreactivity did not display a marked change in any of the groups. Osteocalcin was observed on the distraction side in group 2, which suggested that bone formation is increased. Nitric oxide synthase 2 immunoreactivity was observed on the distraction side in group 2, which is associated with stress and inflammation. The results indicated that the hypertrophy of the cartilage zone and endochondral ossification became more pronounced as the extent and rate of distraction increased.

Ten-Year-Old Boy with a Recurrent Knee Effusion

Ten-Year-Old Boy with a Recurrent Knee Effusion

Stress analysis in the mandibular condyle during prolonged clenching: A theoretical approach with the finite element method

Parafunctional habits, such as bruxism and prolonged clenching, have been associated with functional overloading in the temporomandibular joint (TMJ), which may result in internal derangement and osteoarthrosis of the TMJ. In this study, the distributions of stress on the mandibular condylar surface during prolonged clenching were examined with TMJ mathematical models. Finite element models were developed on the basis of magnetic resonance images from two subjects with or without anterior disc displacement of the TMJ. Masticatory muscle forces were used as a loading condition for stress analysis during a 10 min clenching. In the asymptomatic model, the stress values in the anterior area (0.100 MPa) and lateral area (0.074 MPa) were relatively high among the five areas at 10 min. In the middle and posterior areas, stress relaxation occurred during the first 2 min. In contrast, the stress value in the lateral area was markedly lower (0.020 MPa) than in other areas in the symptomatic model at 10 min. The largest stress (0.050 MPa) was located in the posterior area. All except the anterior area revealed an increase in stress during the first 2 min. The present result indicates that the displacement of the disc could affect the stress distribution on the condylar articular surface during prolonged clenching, especially in the posterior area, probably leading to the cartilage breakdown on the condylar articular surface.