Kenjiro Wakabayashi

MRI Findings in Residual Hip Dysplasia

Background Residual subluxation of the hip is a major problem in pediatric orthopaedics. Corrective surgery by Salter innominate osteotomy is performed for residual subluxation before school age. Common indications for corrective surgery are determined based on the clinical condition, x-ray images, and arthrographic images. However, the surgical indications vary among institutions. Thus, further information that can predict acetabular growth with certainty is needed for precise decision- making. This study focused on signal intensity changes on magnetic resonance (MR) images within the weight-bearing portion of the acetabulum to determine whether these signal intensity changes could predict acetabular growth. Methods Thirty-six patients who showed residual subluxation after reduction of developmental dysplasia of the hip and whose MRIs were taken when they were around 3 years old were studied. Corrective surgery was performed in 14 patients, whereas the remaining 22 patients were followed conservatively. The presence of a high-signal intensity area (HSIA) within the weight-bearing portion of the acetabular cartilage on T2-weighted MR coronal section images was investigated, and the correlation between HSIA presence and acetabular growth was examined. Results All patients who underwent corrective surgery showed an HSIA within the weight-bearing portion of the acetabular cartilage on T2-weighted MR images before surgery. After surgery, all patients showed HSIA disappearance or decrease. In patients who were followed conservatively, HSIA-positive patients had poor acetabular growth, whereas HSIA-negative patients had favorable acetabular growth. Conclusions HSIAs in the acetabular cartilage may be caused by an extraordinary stress load from the femoral head. The presence of HSIA on MRI may prevent acetabular growth. HSIA on MRI appears to be a significant decision-making tool for corrective surgery. Level of Evidence III.

Involvement of the adrenal glands and testis in gap junction formation via testosterone within the male rat anterior pituitary gland.

We investigated the influence of testicular and adrenal androgens on the presence of gap junctions between folliculo‐stellate cells in the anterior pituitary glands of 60‐day‐old Wistar‐Imamichi strain male rats. The animals were separated into six groups: Group A served as the controls and had free access to a normal diet and water, Group B was given a normal diet and 0.9% NaCl for their drinking water as the controls of adrenalectomized groups, Group C was castrated, Group D was adrenalectomized, Group E was both castrated and adrenalectomized, and Group F was also both castrated and adrenalectomized. In addition, the animals of Group F were administered a dose of testosterone that is known to produce high physiological levels of the hormones in plasma. Five rats from each group were sacrificed 1, 2, 3, 4, 5, 6, and 7 days after their respective operation, and the anterior pituitary glands were removed and prepared for observation by transmission electron microscopy. We quantified the number of follicles and gap junctions and calculated the rate of occurrence as the ratio of the number of gap junctions existing between folliculo‐stellate cells per intersected follicle profile. Simultaneous removal of adrenal glands with castration resulted in a significantly decrease in the number of gap junctions, whereas the administration of testosterone to these rats compensated for this change. These observations indicate that the preservation of gap junctions between folliculo‐stellate cells is mainly dependent on androgens from both the testes and adrenal glands in adult male rats. Microsc. Res. Tech., 2012.

Morphometric analysis of the peroneal tubercle using a three-dimensional computed tomography model

BACKGROUND The peroneal tubercle is a small bony ridge located on the lateral wall on the calcaneus immediately inferior to the lateral malleolus and separates the peroneus brevis and peroneus longus tendons. The size and configuration of the peroneal tubercle has been implicated in the pathogenesis of peroneal tendon tears and tenosynovitis and is the increasing object of clinical interest. However, the morphology of the tubercle is difficult to assess with precision. METHODS We utilized a new method to evaluate the three-dimensional (3D) geometry of 46 calcanei from 34 consecutive patients; average patient age was 48.0 years who underwent lower extremity computed tomography (CT) for clinical treatment of non-peroneal tubercle-related conditions. The 3D geometries of calcanei were reconstructed by using the computer software to calculate the surface 3D models. To measure the size of the peroneal tubercle, we virtually excised it from the 3D calcaneus model and made a precise measurement of the height. RESULTS Peroneal tubercles with measured heights of 1mm or more were detected in 65% of the feet, with an average tubercle height of 2.59mm. Peroneal tubercles were larger and more frequent in middle-aged or older than younger patients.

The changes of gap junctions between pituitary folliculo-stellate cells during the postnatal development of zucker fatty and lean rats

We investigated the effect of leptin on the postnatal development of gap junctions between folliculo‐stellate cells by using Zucker fatty (fa/fa) rats that have defects of the functional leptin receptor. Male Zucker fatty rats (fa/fa) and male Zucker lean rats (+/+) were used at each of the following postnatal ages: 20, 30, 40, 50, 60, 70, 80, 90 days, and 1 year. On one of the aforementioned dates, the anterior pituitary glands were prepared for observation by transmission electron microscopy. We quantified the number of follicles and gap junctions, and calculated the rate of occurrence as the ratio of the number of gap junctions existing between folliculo‐stellate cells per intersected follicular profile. In Zucker lean male rats, the number of gap junctions remained relatively constant from days 50 to 90 (0.44 ± 0.02 to 0.49 ± 0.03), and was similar in 1 year old rats (0.47 ± 0.03). These data were statistically higher compared to Zucker fatty male rats. In Zucker fatty male rats, very few gap junctions were observed in 30‐day‐old rats (0.04 ± 0.01: mean ± SE). This disruption of gap junction formation persisted, and the number of gap junctions remained constant and showed a low level from days 40 to 90 (0.11 ± 0.02 to 0.17 ± 0.02); this finding was similar in 1‐year‐old rats (0.17 ± 0.02). These observations indicate that the effect of leptin over the gap junction formation within the anterior pituitary glands was directly mediated by interaction with the functional leptin receptor present on the folliculo‐stellate cells. Microsc. Res. Tech. 77:31–36, 2014.

Reproducibility of acquiring ultrasonographic infant hip images by the Graf method after an infant hip ultrasound training course

PurposeThe objective screening of infant hips using ultrasonography (Graf method) is gaining favor in the diagnosis of developmental dysplasia of the hip in Japan. However, the accuracy of the Graf method is dependent on the examiner’s experience and technique. The purpose of this study was to investigate the reproducibility of acquiring ultrasonic hip images and their evaluation after examiners attended an infant hip ultrasound training course.Materials and methodsUltrasonic images of 70 hips of 35 newborns who were screened by ultrasonography using the Graf method, were evaluated. The images were acquired by two inexperienced examiners who attended the training course. The inter- and intra-examiner measurement errors as well as reproducibility were calculated based on the images obtained.ResultsThe intra-examiner measurement error in the acquired images of the same hip was minor. The inter-examiner measurement error was also small. The intra- and inter-examiner agreements of the Graf classification were high. The intra-examiner reproducibility of the acquired ultrasonic images was substantial, and the inter-examiner reproducibility was almost perfect.ConclusionsOur results demonstrated that inexperienced examiners could obtain ultrasonic infant hip joint images with minor differences and high reproducibility after the training course. Our findings raise the possibility of extending the infant hip ultrasound course in Japan.

Flatfoot in the contralateral foot in patients with unilateral idiopathic clubfoot treated using the foot abduction brace

Abstract While the foot abduction brace (FAB) plays an important role in the Ponseti method, the true function of the FAB in the treatment of idiopathic clubfoot remains unknown. In our clinical experience, we have noted that many patients with unilateral idiopathic clubfoot developed significant flatfoot in the contralateral foot during brace treatment. The purpose of this study was to investigate the natural history of the contralateral foot development during and after brace wear. We also discuss the effect of the FAB on the contralateral foot. We retrospectively reviewed 21 contralateral feet of 21 patients with unilateral idiopathic clubfoot who were treated using the Ponseti method and were conservatively followed up until the FAB was taken off (6 years of age or older). We evaluated flatfoot indicators of the contralateral foot on standing radiographs during and after brace wear and compared them against the normal reference ranges. We also evaluated the changes in the flatfoot indicators of the contralateral foot during and after brace wear. Although there was a significant difference in the flatfoot indicators between the contralateral foot and normal reference ranges during brace wear, there was no significant difference in the flatfoot indicators after brace wear. While there was no significant improvement in flatfoot indicators of the contralateral foot during brace wear, there was a significant improvement or a trend to improve after brace wear. There was no significant correlation between the contralateral flatfoot and original joint laxity. Significant flatfoot deformity was observed in the contralateral foot during brace wear. The contralateral flatfoot persisted during brace wear and improved to within normal reference ranges after brace wear. Our findings suggest that the FAB may influence the development of the contralateral foot, leading to the flatfoot.

Magnetic resonance imaging evaluation of the labrum to predict acetabular development in developmental dysplasia of the hip: A STROBE compliant study

Abstract Recently, more attention has been paid to the role of the acetabular labrum. Therefore, we designed a retrospective cohort study of patients with residual hip dysplasia (RHD) who underwent magnetic resonance imaging (MRI). The objective of this study was to investigate an association between the MRI appearance of the labrum before school age and the natural history of RHD. We retrospectively investigated 45 hips of 40 patients who underwent MRI at about 3 and 4 years of age for RHD and were conservatively followed up with until 6 years of age or older. We evaluated the extent of eversion with a new method that measures the &bgr; angle (MRI &bgr; angle) using landmarks of the Graf method on MRI T2*-weighted images. The outcome measure was the Severin classification at the final follow-up. We compared the radiographic and MRI parameters at approximately 3 and 4 years of age between the good and poor outcome groups. The Student t test or one-way analysis of variance was used to compare the quantitative variables between groups. The Chi-square test was used to perform a ratio comparison. Although there was a significant difference in the center-edge (CE) angle, there was no significant difference in the acetabular index and the ratio of the presence of femoral head necrosis and the break in Shenton line between the good and poor groups. The MRI &bgr; angle was significantly greater in the poor outcome group than in the normal and good outcome groups. The cut-off value of the MRI &bgr; angle to differentiate the good and poor outcome groups was 65°, and its specificity and sensitivity were 92% and 53%, respectively. There was labral eversion on MRI scans in patients with RHD. Acetabular development before adolescence was poorer with greater labral eversion on MRI scans. The specificity for poor acetabular development was high when the MRI &bgr; angle was 65° or more. The MRI &bgr; angle has the potential to predict acetabular development.

Intercellular communications within the rat anterior pituitary. XVI: postnatal changes of distribution of S-100 protein positive cells, connexin 43 and LH-RH positive sites in the pars tuberalis of the rat pituitary gland. An immunohistochemical and electron microscopic study.

The architecture of luteinizing hormone-releasing hormone (LH-RH) nerve ends and the S-100 protein containing folliculo-stellate cells forming gap junctions in the pars tuberalis is basically important in understanding the regulation of the hormone producing mechanism of anterior pituitary glands. In this study, intact male rats 5-60 days old were prepared for immunohistochemistry and electron microscopy. From immunostained sections, the S-100 containing cells in pars tuberalis were first detected on day 30 and increased in number to day 60; this was parallel to the immunohistochemical staining of gap junction protein, connexin 43. LH-RH positive sites were clearly observed on just behind the optic chiasm and on the root of pituitary stalk on day 30. On day 60, the width of layer increased, while follicles and gap junctions were frequently observed between agranular cells in 10 or more layers of pars tuberalis. In the present study, we investigated the sexual maturation of the anterior pituitary glands through the postnatal development of S-100 positive cells, connexin 43 and LH-RH nerves. It is suggested that the folliculo-stellate cell system including the LH-RH neurons in the pars tuberalis participates in the control of LH secretion along with the portal vein system.