Anatomical details of neurogenic heterotopic ossification anterior to the ankylotic hip

Neurogenic heterotopic ossification (NHO) is a common complication in patients with spinal cord injury (SCI) and traumatic brain injury (TBI). Although there are many reports regarding the etiology, pathophysiology, and medical management, few studies elaborate the anatomical details of NHO, which leads to ankylosis of the hip joint. A prospective study on surgical resection of NHO in patients with hip ankylosis was conducted. Radiography and magnetic resonance imaging (MRI) were used to assess the relationship of the NHO block with the blood vessels, peripheral nerve, and surrounding muscles and bones. The anatomical relationships were also assessed and documented during the surgical procedures. NHO, which is anterior to the hip and causes hip ankylosis, settles into tissue planes without involving the tissue itself and does not disrupt the femoral neurovascular structures. The NHO bone block can then fuse to the cortex of adjacent bone. During resection, the normal bony contour should be exposed as a marker to guide the resection in order to avoid iatrogenic fracture.     

Characteristics of prosthetic joint infections due to Enterococcus sp. and predictors of failure: a multi-national study

The objective of this study was to review the characteristics and outcome of prosthetic joint infections (PJI) due to Enterococcus sp. collected in 18 hospitals from six European countries. Patients with a PJI due to Enterococcus sp. diagnosed between January 1999 and July 2012 were retrospectively reviewed. Relevant information about demographics, comorbidity, clinical characteristics, microbiological data, surgical treatment and outcome was registered. Univariable and multivariable analyses were performed. A total of 203 patients met the inclusion criteria. The mean (SD) was 70.4 (13.6) years. In 59 patients the infection was diagnosed within the first 30 days (29.1%) from arthroplasty, in 44 (21.7%) between 31 and 90 days, in 54 (26.6%) between 91 days and 2 years and in 43 (21%) after 2 years. Enterococcus faecalis was isolated in 176 cases (89%). In 107 (54%) patients the infection was polymicrobial. Any comorbidity (OR 2.53, 95% CI 1.18–5.40, p 0.01), and fever (OR 2.65, 95% CI 1.23–5.69, p 0.01) were independently associated with failure. The only factor associated with remission was infections diagnosed later than 2 years (OR 0.25, 95% CI 0.09–0.71, p 0.009). In conclusion, prosthetic joint infections due to Enterococcus sp. were diagnosed within the first 2 years from arthroplasty in >70% of the patients, almost 50% had at least one comorbidity and infections were frequently polymicrobial (54%). The global failure rate was 44% and patients with comorbidities, fever, and diagnosed within the first 2 years from arthroplasty had a poor prognosis.     

一种新型人工颞下颌关节的生物力学分析

目的　建立下颌骨髁突缺损有限元模型,研究新型人工颞下颌关节的应力分布及位移改变。 方法　运用Mimics、Geomagic、Solidworks、ANSYS软件建立含完整牙列的下颌骨右侧髁突缺损有限元模型并分析新型人工颞下颌关节在模拟咬合力加载的情况下假体及下颌骨硬组织的应力分布和位移情况。 结果　下颌骨整体等效应力值均低于20 MPa,最大形变值不超过0.05 mm。 结论　新型人工颞下颌关节能避免过大应力导致的假体断裂和骨质吸收,具有良好的生物力学特性。     

Condylar response to functional therapy with Twin-Block as shown by cone-beam computed tomography

Objective:To evaluate the condylar changes through cone-beam computed tomography (CBCT) images in patients treated with Twin-Block functional appliance.Materials and Methods:In this retrospective study, CBCT images of 30 patients who were treated with the Twin-Block appliance were used. Mandible was segmented and pretreatment and posttreatment (T0 and T1) condylar volume was compared. The angle between sella-nasion-Point A (SNA), angle between sella-nasion-Point B (SNB), angle between Point A-nasion-Point B (ANB), midfacial length (Co-A), mandibular length (Co-Gn), and the distances from right condylion to left condylion (Co_R-Co_L) were also measured on three-dimensional images. Differences were analyzed with Wilcoxon signed rank tests, and Mann-Whitney U-tests were used to compare the scores of male and female participants. Significance was set at P < .05.Results:In this study, a decrease in SNA and ANB (P < .05 and P < .01, respectively) and an increase in SNB (P < .01) were found. Additionally, Co_R-Co_L, Co-Gn, and condylar volume increased at both the left and right sides (P < .01). However, increase at Co-A was not statistically significant (P > .05). Comparison of differences by sex was not statistically significant for all measurements (P > .05).Conclusion:Twin-Block appliance increases condylar volume, mandibular length, and intercondylar distance by stimulating growth of condyle in an upward and backward direction.     

Roles of notch signalling in mandibular condylar cartilage

Importance

Notch proteins are cell surface transmembrane spanning receptors which mediate critically important cellular functions through direct cell–cell contact. Interactions between Notch receptors and their ligands regulate cell fate decisions such differentiation, proliferation and apoptosis in numerous tissues. We have previously shown using immunohistochemistry that Notch1 is localized primarily to the prechondroblastic (chondroprogenitor) layer of the mandibular condylar cartilage (MCC).

Objective

To test if Notch signalling changes patterns of proliferation and differentiation in the MCC and to investigate if Notch signalling acts downstream of Fibroblast Growth Factor 2 (FGF-2).

Methods

Condylar cartilage explants were cultured over serum-free DMEM containing either 0 or 50 nM DAPT, a Notch signal inhibitor. Explants were used for RNA extraction and immunohistochemistry.

Results

Analysis of gene array data demonstrated that the perichondrial layer of the MCC is rich in Notch receptors (Notch 3 and 4) and Notch ligands (Jagged and Delta) as well as various downstream facilitators of Notch signalling. Disruption of Notch signalling in MCC explants decreased proliferation (Cyclin B1 expression) and increased chondrocyte differentiation (Sox9 expression). Moreover, we found that the actions of FGF-2 in MCC are mediated in part by Notch signalling.

Conclusion

These data suggest that Notch signalling contributes to the regulation of proliferation and differentiation in the MCC.     

Ruptured disc after arthroscopic repositioning in the temporomandibular joint: a retrospective magnetic resonance imaging study

Our aim was to explore the incidence of rupture after arthroscopic repositioning of the disc of the temporomandibular joint (TMJ) by reviewing magnetic resonance images (MRI) of the TMJ taken before and after operation, and to investigate correlations retrospectively. We studied 247 patients with anterior disc displacement of the TMJ, and categorised them into 3 groups based on the postoperative MRI. The first group comprised those whose disc ruptured after repositioning, the second those who had a possible rupture of the disc after repositioning, and the third had no rupture of the disc after repositioning. Age, sex, duration of symptoms, maximum incisal mouth opening, whether the anterior disc displacement was unilateral or bilateral, and the Wilkes stage, were included in the analysis. The incidence of rupture (5/247) was 2%. Weak points at the intermediate zone of the disc were found in 4 of the 5 joints. The patients whose discs ruptured were significantly younger than the other 2 groups (p = 0.001). There was no statistically significant difference in preoperative duration of symptoms and mouth opening among the groups. The proportions of unilateral and bilateral disc displacement (p = 0.047) and Wilkes stage (p = 0.027) differed among the 3 groups. The Wilkes stages was significantly more advanced in the ruptured group than in the other 2 groups (p = 0.027) with 4/5 being bilateral. The weak point in the intermediate zone of the disc on MRI could be a sign of rupture. Teenagers and young adults with anterior disc displacement without reduction, particularly those in whom it is bilateral, are at a higher risk of a rupture after repositioning of the disc by arthroscopy.     

Transport distraction osteogenesis as a method of reconstruction of the temporomandibular joint following gap arthroplasty for post-traumatic ankylosis in children: a clinical and radiological prospective assessment of outcome

This clinical and radiographic study investigated the use of transport distraction osteogenesis in unilateral temporomandibular joint (TMJ) ankylosis patients. Six patients aged between 4 and 8 years were selected for the study; the mean preoperative maximal inter-incisal opening (MIO) was 3.5 mm without lateral and protrusive mandibular movements. The ankylotic mass along with the posterior border of the ascending ramus was exposed via ‘lazy-S’ incision. A gap arthroplasty was performed, followed by a ‘reverse L’ osteotomy on the posterior border of the ramus. In-house manufactured extraoral distraction devices were used for this prospective study. Follow-up clinical and radiographic evaluation was carried out for 13–27 months after completion of the activation period. After a mean follow-up of 19 months, the mean MIO was 29.1 mm and the lateral and protrusive movements changed from none to slight. Cone beam computed tomography images of all patients showed remodelled neocondyle created by transport distraction osteogenesis with no statistically significant differences observed for average cancellous bone density, trabecular number, and trabecular spacing between the neocondyle of the operated side (test) and the condyle of the non-operated side (control). Neocondyle formation by transport distraction osteogenesis using the in-house distraction device is a promising treatment option for TMJ reconstruction in ankylosis patients.     

Could different TMJ disc positions observed in MRI cause different sounds? Analysis on a group of subjects with ADD with reduction: a pilot study

Aims:

Magnetic resonance imaging (MRI) is the method of choice for examining soft-tissue pathology of the temporomandibular joint (TMJ). MRI shows a high spatial resolution with accuracy for the identification of internal derangement. Tasaki developed a classification system for disc displacement in the TMJ, identifying eight different types of disc displacements in addition to the superior disc position. This study aims to test the ability of electrosonography (ESG) in discriminating different kinds of disc displacement according to the disc position criteria proposed, comparing the ESG results with those obtained by MRI.

Methodology:

Twenty-seven patients were selected from an initial group of 50 patients with articular disc displacement, selected by means of clinical examinations, according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) and who had both MRI and ESG studies performed. For each patient and for each peak in ESG, both in the opening and closing movements, three different parts of the sound were analyzed. The frequency (Hz) and the mean amplitude (μV) of the sounds were calculated in the three analyzed windows. Afterwards, gathering the data for the Tasaki’s classes and dividing opening and closing sounds, the number of peaks was calculated, as well as average and standard deviations for both the Hz and µV.

Results:

The peak frequency shows significant differences between different disc positions during the first and second third of the opening phase and during the first third of the closing phase. The peak amplitude shows significant differences between different disc positions during all of the opening and closing phases.

Conclusions:

Although limited by sample size, the present study shows the presence of different sounds with different Hzs and μVs associated with different disc positions that were recorded with ESG.