Ultrasonography of the borderline between normal and pathological state of the hip in newborn infants (borderline hip)]

Infant hips are classified, according to Graf, in 4 US types on the basis of the morphologic changes in both the cartilaginous and the bony roofs (type I, II, III, IV). Out of 6,000 examined hips, 170 (2.8%) were considered, which could be classified neither as type I (mature) nor as type II (delayed/immature ossification). These hips were called borderline hips. They exhibited some characteristic US features: good bone modeling, rounded cotyle, and alpha angle 60 degrees +/- 2. They were always observed during the first month of the patients' life. Anamnestic data were not specific (27.5% breech delivery, and 13% oligohydramnios); clinics sometimes overestimated the actual anatomic development (64/170 cases with positivity of Ortolani's sign and/or restricted abduction; 25% of patients presented with no suspicious signs). Dynamic hip examination showed only physiological cranial deflection of the cartilaginous roof. Finally, borderline hips developed into type I hips in 99% of cases, within the third month of the patients' life.     

Error in the calibration of the MgATP chemical-shift limit: effects on the determination of free magnesium by 31P NMR spectroscopy.

The measurement of free intracellular magnesium (Mg2+) using the 31P chemical shifts of ATP requires the use of appropriate calibration solutions to determine the chemical-shift limits delta ATP alpha beta and delta MgATP alpha beta. Solutions containing excess Mg2+ contain significant amounts of Mg2ATP and yield positive errors in the value of delta MgATP alpha beta. For physiological applications this may overestimate free intracellular Mg2+ by as much as 300%. This error may be minimized if appropriate mole ratios of Mg2+/ATP are used to calibrate delta MgATP alpha beta.     

Comparable ultrasound measurements of ten anatomical specimens of infant hip joints by the methods of Graf and Terjesen

PURPOSE: To define which sonographic section planes relative to the acetabular inlet plane will produce analyzable images with the methods of Graf and Terjesen. MATERIAL AND METHODS: Anatomical specimens of infant hip joints were investigated in a water bath using the methods of Graf and Terjesen. Acetabular position was varied in defined increments with respect to the ultrasound beam. The alpha angles and the femoral head coverage (FHC) were measured. RESULTS: To obtain images analyzable by the two methods, the ultrasound beam had to intersect with the acetabular inlet plane at defined angles. The acetabular notch had to be anteriorly rotated from the ultrasound beam plane by at least 20 degrees. Beam entry within a 50 degrees sector posterior to the perpendicular on the inlet plane resulted in analyzable images. The stepwise multiple linear regression analysis showed that alpha angles and FHC were much affected by the coronal-plane transducer tilt. CONCLUSION: The fact that caudal tilts of the transducer are associated with reduced alpha angles and FHC values should be kept in mind in clinical ultrasound investigations. It is recommended that the transducer should be put on the greater trochanter perpendicular to the transverse axis of the body.     

Pelvic angles: a mathematically rigorous definition which is consistent with a conventional clinical understanding of the terms

The most common definition of pelvic angles in conventional gait analysis uses the sequence tilt, obliquity, rotation. This is used in most commercially available gait analysis software. This definition of angles, however, is not in agreement with the conventional clinical understanding of the terms when both tilt and rotation are large. This paper shows that by using the sequence rotation, obliquity, tilt it is possible to make a mathematically rigorous definition of pelvic angles which it is consistent with that conventional clinical usage. A model of the pelvis in which the hips are maintained level is developed. It is shown that as tilt and rotation are varied, in a clinically relevant range, that obliquity measured using the conventional sequence can be as much as 10 degrees. By definition it is 0 degrees for the new sequence. A case study shows that measures of obliquity correlate better with the relative height of the hips using the new sequence than the conventional one. It is proposed that use of the new sequence would lead to data which is easier to interpret clinically.     

Role of echography in the diagnosis and treatment monitoring of congenital acetabular dysplasia. Personal experience with 2000 examined children

Since 1987 the authors have used sonography (US) as the means to detect dysplasia and congenital dislocation of infant hips, to define severity of the disease, and to monitor the results during treatment. In this paper the authors report their experience in 2000 examined babies. In 20 young patients, mainly females, 25 pathologic joints were detected and classified as 2c-4 hips. Orthopedic treatment employed Pavlick harness and, in case of partial success, Milgram abduction pillow too. This treatment has always been successful, except for a case with severe dislocation with echostructural changes in the acetabular cartilage. In this case, surgery was necessary. "Delayed ossification" (type 2b hips) and physiological immatury (type 2a hips) with alpha angle greater than or equal to 55 degrees were not splinted in abduction: normal maturity has always been attained without dysplastic involutions. Our experience confirmed US value in the early diagnosis of congenital acetabular dysplasia, when clinics exhibited evident limitations. Nonetheless, management and economical problems are still to be solved, due to the relationship of the widespread use of US in infant population and to its successful results, also considering the low incidence of the examined pathologic condition.     

Comparison of bone mineral density in both hips

Dual-photon absorptiometry (DPA) was performed on both hips of 40 patients to determine if the calculated bone-mineral density (BMD) of one hip could be used to predict the BMD of the opposite hip. For the Ward triangle, femoral neck, and greater trochanter the correlation coefficients between the BMD of the two hips was .920, .917, and .843, and the standard errors (SE) of the estimate for the linear regression of the left hip on to the right were 0.067, 0.063, and 0.077 g cm-2. The absolute error of predicting one hip from the other was not a function of BMD and thus the relative error increases with lower BMD values. The relative errors were 17%, 8%, and 7% for BMDs of 0.4, 0.8, and 1.0 g cm-2, respectively. The interobserver variability was small, with an r value of .96 and an SE of the estimate value of 0.036 g cm-2. The relative error in the mild-to-moderate osteoporosis categories was 2.5 times the precision of the instrument, indicating that the asymmetry of BMD is due to real differences between hips. Therefore the BMD of one hip cannot be used to predict that of the other with sufficient accuracy to discriminate clinically relevant trends in BMD.     

Relative electron density calibration of CT scanners for radiotherapy treatment planning

Several authors have reported data on the variation of Hounsfield numbers with electron density in CT scanners. The data can be fitted with a double straight line approach. For non-bone tissues (or phantom materials with similar atomic numbers) the data from all authors can be fitted to a single straight line. For bone-like materials the line varies between authors. The method used to measure electron density has a greater effect than the differences between scanners, or the kilovoltage used on a given scanner. The effect of variation of these slopes on the accuracy of radiotherapy treatment planning is analysed. For typical radiotherapy beams, to produce a 1% error in dosimetry would require errors of over 8% in bone electron density. Using a single pair of calibration lines for all the scanners reported would give dosimetric errors of under 0.8%. A formula is recommended as a default for use in planning systems in circumstances where no data are available for a particular scanner.     

The effect of computed tomographic scan orientation on information loss in the three-dimensional reconstruction of tripod zygomatic fractures

Fractures modeled in the dried skull indicate that the initial plane of computed tomography (CT) section contributes to the accuracy of three-dimensional (3D) images generated from two-dimensional (2D) CT data. The authors retrospectively analyzed seven clinical cases of tripod zygomatic fractures that were imaged with both axial and coronal CT scan orientations. Ten observers evaluated paired 3D CT images, one generated from 2D CT data in the axial plane and the other generated from coronal 2D CT data, for each of the seven cases of tripod fractures. A G-E 9800 CT scanner with the 3D98 Quick processing system were used for the 3D reconstructions. The axial scan orientation resulted in 3D reconstructions that had significantly less information loss in the display of the tripod fractures than did those based on coronal CT data (P less than .025).     

Predicting postoperative gait in cerebral palsy

In this work, postoperative lower limb kinematics are predicted with respect to preoperative kinematics, physical examination and surgery data. Data of 115 children with cerebral palsy that have undergone single-event multilevel surgery were considered. Preoperative data dimension was reduced utilizing principal component analysis. Then, multiple linear regressions with 80% confidence intervals were performed between postoperative kinematics and bilateral preoperative kinematics, 36 physical examination variables and combinations of 9 different surgical procedures. The mean prediction errors on test vary from 4° (pelvic obliquity and hip adduction) to 10° (hip rotation and foot progression), depending on the kinematic angle. The unilateral mean sizes of the confidence intervals vary from 5° to 15°. Frontal plane angles are predicted with the lowest errors, however the same performance is achieved when considering the postoperative average signals. Sagittal plane angles are better predicted than transverse plane angles, with statistical differences with respect to the average postoperative kinematics for both plane’s angles except for ankle dorsiflexion. The mean prediction errors are smaller than the variability of gait parameters in cerebral palsy. The performance of the system is independent of the preoperative state severity of the patient. Even if the system is not yet accurate enough to define a surgery plan, it shows an unbiased estimation of the most likely outcome, which can be useful for both the clinician and the patient. More patients’ data are necessary for improving the precision of the model in order to predict the kinematic outcome of a large number of possible surgeries and gait patterns.     

Benefits of routine use of coronal and sagittal reformations in multi-slice CT examination of the abdomen and pelvis

AIM: To evaluate the usefulness of coronal and sagittal reformations from isotropic abdomino-pelvic computed tomography (CT) examinations. METHODS: Fifty consecutive abdomino-pelvic CT examinations were reconstructed into two sets of axial source images: 0.9 mm section width with 0.45 mm reconstruction interval (isotropic) and 4 mm section width with 3 mm reconstruction interval. The isotropic dataset was reformatted into coronal and sagittal stacks with 4 mm section widths. Three readers independently reviewed the three image sets with 4 mm section widths. The coronal and sagittal reformations were compared with the axial images, in the same sitting, for depiction of lesions in various abdominal organs. RESULTS: There was better visualization of lesions in the liver, kidneys, mesentery, lumbar spine, major abdominal vessels, urinary bladder, diaphragm and hips on the coronal reformations compared with source axial images (p<0.05). Sagittal reformations scored better than axial source images for showing lesions in the liver, thoracic spine, abdominal vessels, uterus, urinary bladder, diaphragm and hips (p<0.05). The coronal and sagittal series showed significant additional information in 23 and 17% of patients, respectively. CONCLUSION: Radiologists should consider the routine review of at least one additional plane to the axial series in the interpretation of abdomino-pelvic CT studies.     

Accuracy of a 3D temporal scanning system for gait analysis: Comparative with a marker-based photogrammetry system

BackgroundCombining the accuracy of marker-based stereophotogrammetry and the usability and comfort of markerless human movement analysis is a difficult challenge. 3D temporal scanners are a promising solution, since they provide moving meshes with thousands of vertices that can be used to analyze human movements.Research questionCan a 3D temporal scanner be used as a markerless system for gait analysis with the same accuracy as traditional, marker-based stereophotogrammetry systems?MethodsA comparative study was carried out using a 3D temporal scanner synchronized with a marker-based stereophotogrammetry system. Two gait cycles of twelve healthy adults were measured simultaneously, extracting the positions of key anatomical points from both systems, and using them to analyze the 3D kinematics of the pelvis, right hip and knee joints. Measurement differences of marker positions and joint angles were described by their root mean square. A t-test was performed to rule out instrumental errors, and an F-test to evaluate the amplifications of marker position errors in dynamic conditions.ResultsThe differences in 3D landmark positions were between 1.9 and 2.4 mm in the reference pose. Marker position errors were significantly increased during motion in the medial-lateral and vertical directions. The angle relative errors were between 3% and 43% of the range of motion, with the greatest difference being observed in hip axial rotation.SignificanceThe differences in the results obtained between the 3D temporal scanner and the marker-based system were smaller than the usual errors due to lack of accuracy in the manual positioning of markers on anatomical landmarks and to soft-tissue artefacts. That level of accuracy is greater than other markerless systems, and proves that such technology is a good alternative to traditional, marker-based motion capture.     

Conventional radiography in transient synovitis of the hip in children

Conventional radiography was performed at diagnosis and at follow-up 5 to 9 months later in 70 children with transient synovitis of the hip. Twenty-four of the patients also had CT examination at diagnosis. The cartilaginous and osseous reaction in the conventional antero-posterior radiographs was studied as was the relation between the radiographic and CT findings concerning fat planes, joint effusion, and position of the hip joint. At diagnosis there was significant increase in the medial joint space and at follow-up examination there was significant increase in medial and cranial joint space, metaphyseal width and acetabular roof width. There was a correlation of a bulging lateral 'capsular fat plane' to the position of abduction in the affected hip which explains the asymmetry in the lateral fat plane observed in these patients.     

Between-session reliability of skin marker-derived spinal kinematics during functional activities

BackgroundSkin marker-based analysis of functional spinal movement is a promising method for quantifying longitudinal effects of treatment interventions in patients with spinal pathologies. However, observed day-to-day changes might not necessarily be due to a treatment intervention, but can result from errors related to soft tissue artifacts, marker placement inaccuracies or biological day-to-day variability.Research questionHow reliable are skin marker-derived three-dimensional spinal kinematics during functional activities between two separate measurement sessions?MethodsTwenty healthy adults (11 females/9 males) were invited to a movement analysis laboratory for two visits separated by 7–10 days. At each visit, they performed various functional activities (i.e. sitting, standing, walking, running, chair rising, box lifting and vertical jumping), while marker trajectories were recorded using a skin marker-based 10-camera optical motion capture system and used to calculate sagittal and frontal plane spinal curvature angles as well as transverse plane segmental rotational angles in the lumbar and thoracic regions. Between-session reliability for continuous data and discrete parameters was determined by analyzing systematic errors using one sample T-tests as well as by calculating intraclass correlation coefficients (ICCs) and minimal detectable changes (MDCs).Results and SignificanceThe analysis indicated high relative consistency for sagittal plane curvature angles during all activities, but not for frontal and transverse plane angles during walking and running. MDCs were mostly below 15°, with relative values ranging between 10 % and 750 %. This study provides important information that can serve as a basis for researchers and clinicians aiming at investigating longitudinal effects of treatment interventions on spinal motion behavior in patients with spinal pathologies.     

Colour Doppler Ultrasound Assessment of the Normal Neonatal Hip

Objective

To determine the morphology and hemodynamic characteristics of the arterial vessels of the proximal femur according to specific anatomic regions in asymptomatic neonates in 2 pediatric-based health care institutions.

Methods

Forty-three neonates (29 female, 14 male; age range, 2 d–3 mo; median age, 3 d) were enrolled in the study. Thirty-two (37%) of 86 hips were classified as Graf type IIA joints (mean alpha angle, 56.0° ± 2.7°), and 54 (63%) were classified as type I joints (mean alpha angle, 65.0° ± 4.6°).

Results

Colour and spectral Doppler imaging identified vessels running along the acetabular labrum, epiphyseal vessels, and femoral neck. We showed 4 different patterns of vascularity of the hips: radial, parallel, mixed radial–parallel, and indeterminate, however, they were not related to the hip maturity (P = .3, coronal plane; P = .62, transverse plane) or to the amount of colour pixels identified in each region (P = .35). The mean number of pixels in the ligamentum teres region was significantly higher than that in other regions of interest (P = .03). Except for the acetabular labrum arteries, Doppler spectrum waveforms of proximal femur arteries presented with low resistivity. There was a tendency towards females' acetabular arteries presenting with lower peak systolic velocities than males' acetabular arteries (P = .06).

Conclusions

Colour Doppler spectrum waveforms and intensity of vascularity in normal neonatal hips differ according to the anatomic region under evaluation. This observation deserves further investigation on its role on the physiopathogenesis of neonatal hip disorders.     

Neonatal hip: from anatomy to cost-effective sonography

Therapeutic success in treating congenital dysplasia of the hip is associated with early diagnosis, but the specific neonatal anatomy makes screening difficult. The purpose of this study was to determine whether this specific neonatal anatomy is taken into account by current ultrasound (US) techniques. Anatomic studies were performed on 22 hips, US examinations on 7750 neonatal hips; 2370 untreated hips were reexamined at 1 month by US and at 3 months by X-ray. The transformation of the neonatal cartilaginous acetabulum into an osseous cavity is dependent on harmonious metaphyseal growth and a properly seated femoral head. Defects in the acetabular roof, together with displacement of the femoral head, cause an abnormal anatomical relationship which leads to further deformities. The described sonographic techniques give only partial information on these specific abnormalities. The sonographic monoplanar methods as used in Graf's technique, which relies largely on acetabular development, lead to difficulties in assessing posterior coverage of the femoral head and difficulties in assessing alignment of the metaphyseal weight-bearing surface with the femoral head. Combining Graf's morphological analysis with Novick's dynamic technique enables one to more accurately define the relationship of the femoral head and the acetabulum and increases the reliability and predictive value of the examination, while reducing the number of doubtful cases. This makes screening cost effective. Received: 20 February 1997; Revision received: 28 August 1997; Accepted: 7 January 1998     

Quantitative assessment of the influence of location, internal temperature, idle time, and normalization on the sensitivity of a mobile PET/CT scanner

The superiority of PET/CT and (18)F-FDG imaging in cancer assessment has created the need in rural community hospitals to acquire this technology. However, high cost and lack of patient volume have prohibited these institutions from attaining in-house scanners. By using mobile PET/CT scanners, small rural hospitals are able to deliver this valuable clinical tool to their patients. As mobile PET/CT scanners are shifted from one site to another, however, they are exposed to harsher and frequently varying ecologic conditions that can alter their performance. Because of the importance of the standardized uptake value in cancer evaluation and its linear relationship to the sensitivity of the scanner, we investigated conditions affecting the sensitivity of the mobile PET/CT scanner. METHODS: We used a (68)Ge cylindric phantom with 2 bed frames scanned for 3 min each to simulate a patient to assess quantitatively the influence of location, increase in scanner internal temperature, idle time, and normalization on the sensitivity of the mobile PET/CT scanner. The raw phantom data were acquired and reconstructed with the parameters used for oncology patients. The scanner sensitivity values (Bq/mL) were obtained from circular regions of interest drawn on the phantom images. These values were compared with the true phantom activity concentration after it was decay-corrected to the specific scanning day. RESULTS: The average sensitivity errors (mean +/- SD) of this mobile PET/CT scanner at sites 1-4 were 1.84% +/- 0.98%, 2.43% +/- 2.05%, 2.08% +/- 0.91%, and 4.34% +/- 1.93%, respectively. A 41.17% increase in the scanner internal temperature decreased its sensitivity by an average of 16.09% +/- 3.58%. After day 1 and day 2, its average sensitivity errors were 3.27% +/- 0.01% and 2.65% +/- 0.02%, respectively. Before and after normalization, the average sensitivity errors were 3.06% +/- 1.37% and 2.69% +/- 1.69%, respectively. CONCLUSION: Temperature and normalization affected the sensitivity of the scanner the most and should be monitored closely, with normalization performed as recommended by the manufacturer.     

The accuracy of CT in the staging of carcinoma of the prostate

Previous studies have reported the accuracy of CT in distinguishing stages of prostatic carcinoma, but they lack uniform surgical proof of histopathologic stage. We evaluated CT scans in 32 patients who underwent radical prostatectomy to assess its role in the preoperative staging of prostatic carcinoma. Two experienced radiologists blindly interpreted CT scans of the pelvis; they looked for evidence of tumor beyond the prostatic capsule and involvement of the seminal vesicles (stage C) or involvement of pelvic lymph nodes (stage D). Sixty-four interpretations in 32 patients yielded a specificity of 75% for predicting stages A or B disease (local disease), a sensitivity of 50% for the prediction of stages C or D, and an overall accuracy of staging of 67%. Interpretation errors were due to an inability to detect lymph node metastases, errors in evaluating the seminal vesicles, and errors in interpreting densities surrounding the prostate gland. Our data suggest that CT should not be used to influence decisions concerning surgical vs nonsurgical treatment in patients with clinically staged local disease and is only useful when unsuspected metastatic nodal disease is detected.     

The effect of immobilisation on localisation error in the radiotherapy of head and neck cancer.

With the use of treatment verification films for the detection of localisation error (LE), a study was undertaken to determine the effect of change in position and immobilisation on LE in the radiotherapy of patients with head and neck cancer. For those patients not immobilised and treated in the lateral position, 28 errors were recorded in a review of 172 films, giving an error incidence of 16%. For patients immobilised by bite block and treated in the supine position, a total of four errors were recorded on review of 382 films, giving an error incidence of 1%. The reduction of LE from 16% to 1% by supine positioning and bite block immobilisation was significant with a P value of less than 0.001. The potential significance of LE in relation to CNS injury and tumour recurrence is discussed.     

Validity and comparisons of tibiofemoral orientations and displacement using a femoral tracking device during early to mid stance of walking

First, this study compares tibiofemoral motion during walking using a new femoral tracking device (FTD) and bone mounted markers in a single subject (n=1). The results suggest errors of <3 degrees in tibiofemoral angles using the FTD method over the first 85% of stance. Second, this study compares tibiofemoral angles and displacement during walking using the FTD method and a modified Helen Hayes method to track the femur in 13 subjects (n=13). The results suggest similar tibiofemoral angles in the sagittal and frontal planes using the two methods (average root mean square (RMS) differences <3.6+/-1.5 degrees ), and a large decrease in the transverse plane angles (average RMS differences=6.5+/-1.9 degrees ) and estimates of tibiofemoral displacement (P<0.05) using the FTD method. The FTD method presents a practical alternative to recording tibiofemoral transverse plane angles and displacement over the first 85% of stance.