Contrast-enhanced microCT (EPIC-µCT) ex vivo applied to the mouse and human jaw joint.

OBJECTIVES: The temporomandibular joint (TMJ) is susceptive to the development of osteoarthritis (OA). More detailed knowledge of its development is essential to improve our insight into TMJ-OA. It is imperative to have a standardized reliable three-dimensional (3D) imaging method that allows for detailed assessment of both bone and cartilage in healthy and diseased joints. We aimed to determine the applicability of a contrast-enhanced microCT (µCT) technique for ex vivo research of mouse and human TMJs. METHODS: Equilibrium partitioning of an ionic contrast agent via µCT (EPIC-µCT) was previously applied for cartilage assessment in the knee joint. The method was ex vivo, applied to the mouse TMJ and adapted for the human TMJ. RESULTS: EPIC-µCT (30-min immersion time) was applied to mouse mandibular condyles, and 3D imaging revealed an average cartilage thickness of 110 ± 16 µm. These measurements via EPIC-µCT were similar to the histomorphometric measures (113 ± 19 µm). For human healthy OA-affected TMJ samples, the protocol was adjusted to an immersion time of 1 h. 3D imaging revealed a significant thicker cartilage layer in joints with early signs of OA compared with healthy joints (414.2 ± 122.6 and 239.7 ± 50.5 µm, respectively). A subsequent significant thinner layer was found in human joints with late signs of OA (197.4 ± 159.7 µm). CONCLUSIONS: The EPIC-µCT technique is effective for the ex vivo assessment of 3D cartilage morphology in the mouse as well as human TMJ and allows bone-cartilage interaction research in TMJ-OA.

Mineral heterogeneity affects predictions of intratrabecular stress and strain.

Knowledge of the influence of mineral variations (i.e., mineral heterogeneity) on biomechanical bone behavior at the trabecular level is limited. The aim of this study is to investigate how this material property affects the intratrabecular distributions of stress and strain in human adult trabecular bone. Two different sets of finite element (FE) models of trabecular samples were constructed; tissue stiffness was either scaled to the local degree of mineralization of bone as measured with microCT (heterogeneous) or tissue stiffness was assumed to be homogeneous. The influence of intratrabecular mineral heterogeneity was analyzed by comparing both models. Interesting effects were seen regarding intratrabecular stress and strain distributions. In the homogeneous model, the highest stresses were found at the surface with a significant decrease towards the core. Higher superficial stresses could indicate a higher predicted fracture risk in the trabeculae. In the heterogeneous model this pattern was different. A significant increase in stress with increasing distance from the trabecular surface was found followed by a significant decrease towards the core. This suggests trabecular bending during a compression. In both models a decrease in strain values from surface to core was predicted, which is consistent with trabecular bending. When mineral heterogeneity was taken into account, the predicted intratrabecular patterns of stress and strain are more consistent with the expected biomechanical behavior as based on mineral variations in trabeculae. Our findings indicate that mineral heterogeneity should not be neglected when performing biomechanical studies on topics such as the (long-term or dose dependent) effects of antiresorptive treatments.

Biomechanical effect of mineral heterogeneity in trabecular bone.

Due to daily loading, trabecular bone is subjected to deformations (i.e., strain), which lead to stress in the bone tissue. When stress and/or strain deviate from the normal range, the remodeling process leads to adaptation of the bone architecture and its degree of mineralization to effectively withstand the sustained altered loading. As the apparent mechanical properties of bone are assumed to depend on the degree and distribution of mineralization, the goal of the present study was examine the influences of mineral heterogeneity on the biomechanical properties of trabecular bone in the human mandibular condyle. For this purpose nine right condyles from human dentate mandibles were scanned and evaluated with a microCT system. Cubic regional volumes of interest were defined, and each was transformed into two different types of finite element (FE) models, one homogeneous and one heterogeneous. In the heterogeneous models the element tissue moduli were scaled to the local degree of mineralization, which was determined using microCT. Compression and shear tests were simulated to determine the apparent elastic moduli in both model types. The incorporation of mineralization variation decreased the apparent Young's and shear moduli by maximally 21% in comparison to the homogeneous models. The heterogeneous model apparent moduli correlated significantly with bone volume fraction and degree of mineralization. It was concluded that disregarding mineral heterogeneity may lead to considerable overestimation of apparent elastic moduli in FE models.

Regional variations in mineralization and strain distributions in the cortex of the human mandibular condyle.

The strain (i.e. deformation) history influences the degree of mineralization of cortical bone (DMB) as well as its osteonal microstructure. This study aimed to examine the relationships of stress and strain distributions with the variations in DMB and the osteonal orientations in the cortical bone of the human mandibular condyle. It was hypothesized that strains are inversely proportional to local DMB and that the principal strains are oriented parallel to the osteons. To test this, ten human mandibular condyles were scanned in a microCT system. Finite element models were created in order to simulate static clenching. Within each condyle, 18 volumes of interest were selected to analyze regional differences in DMB, stress and strains. Subchondral bone showed a lower equivalent strain (2652+/-612 muepsilon) as compared to the anterior (p=0.030) and posterior cortex (p=0.007) and was less mineralized. Contrary to our hypothesis, the results show that strains correlated positively with regional variations in DMB (r=0.750, p<0.001). In the anterior and the posterior cortex, the first principal strain was parallel to the cortical surface and oriented supero-inferiorly with a fan-like shape. In subchondral bone, the first and the second principal strain were parallel to the surface and oriented antero-posteriorly and medio-laterally, respectively. It was concluded that the strain distributions, by themselves, cannot explain the regional differences found in DMB. In agreement with our second hypothesis, the orientation of the osteonal network of the mandibular condyle was closely related to the strain orientations. The results of this study suggest that the subchondral and the cortical bone are structured to ensure an optimal load distribution within the mandibular condyle and have a different mechanical behaviour. Subchondral bone plays a major role in the transmission of the strains to the anterior and posterior cortex, while these ensure an optimal transmission of the strains within the condylar neck and, eventually, to the mandibular ramus.

Porosity of human mandibular condylar bone.

Quantification of porosity and degree of mineralization of bone facilitates a better understanding of the possible effects of adaptive bone remodelling and the possible consequences for its mechanical properties. The present study set out first to give a three-dimensional description of the cortical canalicular network in the human mandibular condyle, in order to obtain more information about the principal directions of stresses and strains during loading. Our second aim was to determine whether the amount of remodelling was larger in the trabecular bone than in cortical bone of the condyle and to establish whether the variation in the amount of remodelling was related to the surface area of the cortical canals and trabeculae. We hypothesized that there were differences in porosity and orientation of cortical canals between various cortical regions. In addition, as greater cortical and trabecular porosities are likely to coincide with a greater surface area of cortical canals and trabeculae available for osteoblastic and osteoclastic activity, we hypothesized that this surface area would be inversely proportional to the degree of mineralization of cortical and trabecular bone, respectively. Micro-computed tomography was used to quantify porosity and mineralization in cortical and trabecular bone of ten human mandibular condyles. The cortical canals in the subchondral cortex of the condyle were orientated in the mediolateral direction, and in the anterior and posterior cortex in the superoinferior direction. Cortical porosity (average 3.5%) did not differ significantly between the cortical regions. It correlated significantly with the diameter and number of cortical canals, but not with cortical degree of mineralization. In trabecular bone (average porosity 79.3%) there was a significant negative correlation between surface area of the trabeculae and degree of mineralization; such a correlation was not found between the surface area of the cortical canals and the degree of mineralization of cortical bone. No relationship between trabecular and cortical porosity, nor between trabecular degree of mineralization and cortical degree of mineralization was found, suggesting that adaptive remodelling is independent and different between trabecular and cortical bone. We conclude (1) that the principal directions of stresses and strains are presumably directed mediolaterally in the subchondral cortex and superoinferiorly in the anterior and posterior cortex, (2) that the amount of remodelling is larger in the trabecular than in the cortical bone of the mandibular condyle; in trabecular bone variation in the amount of remodelling is related to the available surface area of the trabeculae.

Degree and distribution of mineralization in the human mandibular condyle.

The degree of mineralization of bone (DMB) in the mandibular condyle reflects the age and remodeling rate of the bone tissue. Quantification of DMB facilitates a better understanding of possible effects of adaptive remodeling on mineralization of the condyle and its possible consequences for its mechanical quality. We hypothesized differences in the degree and distribution of mineralization between trabecular and cortical bone and between various cortical regions. Microcomputed tomography was used to measure mineralization in 10 human mandibular condyles. Mean DMB was higher in cortical (1,045 mg hydroxyapatite/cm(3)) than in trabecular bone (857 mg/cm(3)) and differed significantly between cortical regions (anterior 987 mg/cm(3), posterior 1,028 mg/cm(3), subchondral 1,120 mg/cm(3)). The variation of DMB distribution was significantly larger in the anterior cortex than in the posterior and subchondral cortex, indicating a larger amount of heterogeneity of mineralization anteriorly. Within the cortical bone, DMB increased with the distance from the cortical canals to the periphery. Similarly, the DMB of trabecular bone increased with the distance from the surface of the trabeculae to their cores. It was concluded that the rate of remodeling differs between condylar trabecular and cortical bone and between cortical regions and that DMB is not randomly distributed across the bone. The difference in DMB between condylar cortical and trabecular bone suggests a large difference in Young's modulus.

True hermaphroditism with hydrocolpos.

A case of true hermaphroditism with hydrocolpos in a 7-month-old infant is presented. This is, to the authors' knowledge reported case of association of both anomalies. Hydrocolpos is a clinical entity characterized by vaginal distension with accumulation of fluid, which can cause respiratory embarrassment and urinary, intestinal and circulatory obstruction. It is a condition of great rarity. It is usually detected in the neonatal period, although it has been reported in older children, and it calls for urgent treatment. True hermaphroditism is a rare form of intersexuality, which can only be considered to exist if both male and female elements can be identified in the gonad.

Cold knife optical urethrotomy.

Cold knife optical urethrotomy with the Sachse urethrotome was used in 44 patients with urethral strictures. Appraisal if the results, after a mean follow-up of fourteen months, showed 77.3 per cent success rate regarding urine flow rates and 81.8 per cent regarding subjective response of the patient.

[The place of surgery in the treatment of testicular tumors other than seminoma (author's transl)]. / Het aandeel van de chirurgie bij de behandeling van niet-seminomateuze testistumoren.

Surgery plays an important part in the treatment of non seminomatous testicular tumors. An oncologically correct technique of orchidectomy is the first essential if the better prognosis of these tumors, noted in the past decade, is to be further improved. The testis should be removed through an inguinal approach. Radical retroperitoneal lymphadenectomy is gaining more favour at the present time. This operation, routinely performed in the US. is being performed more frequently in Europe. The justification for this major operation with a definite morbidity is to be found in the better survival rate achieved in patients undergoing surgery as compared to that achieved using other treatment modalities. A description of the operative technique delineates the magnitude of the surgery but also shows that, working methodically the operation is feasible.

Anterior vaginal repair, cause of troublesome voiding disorders?

Clinical experience and urodynamic observations in 85 female patients with voiding disorders after anterior vaginal repair are presented. Iatrogenic or persistent urinary stress incontinence (72%), irritable trigone syndrome (48%), bladder outlet obstruction (40%), unstable bladder (25%) and recurrent cystitis (23.5%) were the most frequent findings. Also, 5 cases of urogenital fistula and 2 cases of loss of a great part of the urethra were noted. Attempts to cure these complications with different pharmacologic agents and/or surgical methods were often disappointing.

Uretero-neo-cystostomy in renal transplantation. Is an antireflux mechanism mandatory?

We report a retrospective analysis of 120 kidney transplantations in which a simple end-to-end ureteric implantation in the bladder without antireflux mechanism was made. From this study no greater incidence of vesico-ureteric reflux could be demonstrated and, even when present, reflux neither interfered with graft function nor caused an increased incidence of recurrent urinary tract infections. The incidence of other urological complications (leakage, obstruction) being equal, this very simple technique yielded in our hands the best results and we recommend its use in kidney transplantation.

Successful management of postoperative hemorrhage of the kidney by selective transcatheter embolization.

A case is reported where postoperative hemorrhage from the kidney was successfully managed by selective transcatheter embolization of the bleeding vessel. A review of the literature reveals that only three papers have been published dealing with selective embolization for controlling hemorrhage from the kidney. Our case is another illustration of the possibilities and usefulness of this method of treatment in the management of persistent postoperative hemorrhage.

Intrarenal arteriovenous fistula following renal allograft biopsy.

Arteriovenous fistulae in renal allograft are rarely mentioned in papers dealing with vascular complications after renal transplantations. 2 cases of such central fistulae are reported. In our patients the fistulae remained asymptomatic and were incidentally detected, so that neither surgical nor medical measures had to be taken. Reviewing the rather scarce literature on this subject the etiology, symptomatology, prevention and therapy of these fistulae are discussed.

Epidermoid cyst of the testis.

Surgical exploration of a mass in the right testis revealed an epidermoid cyst. In the literature some controversy exists on surgical treatment of this lesion. Orchiectomy seems to be recommended although several patients treated by simple enucleation had an uneventful follow-up from 6 to 15 years.