Bilateral Slips Research Articles

Presence and magnitude of anterior physeal separation in slipped upper femoral epiphysis helps identifying those at high risk for avascular necrosis

AimsWe sought to determine if the magnitude of anterior physeal separation (APS) in slipped upper femoral epiphysis was a predictor for the subsequent development of avascular necrosis (AVN). Anterior Physeal Separation (APS) is defined as the distance between the anterior lip of the bony capital epiphysis and the lateral corresponding point of the adjacent bony metaphysis on the Lauenstein radiographic view. It represents hinging of the posterior aspect of the metaphysis with the anterior epiphysis lifting away from its adjacent metaphysis, indicating instability and potential vulnerability of the vessels. Patients and MethodsA retrospective review of all patients treated regionally for slipped upper femoral epiphysis over a 9 year period (2010–2018 inclusive) were identified. Data regarding demographics, radiological parameters and outcomes was recorded. APS was measured on a Launestein radiograph view, with the patient supine, the hip and knee are flexed to 40°, and the hip externally rotated 45°, with film-focus distance of 100 cm. Analysis of the APS was performed to validate a threshold above which AVN occurs. ResultsWe identified 147 hips in 142 patients, of which 5 had bilateral slips at the time of presentation. Average anterior physeal separation was 3.8 ± 1.8 mm, with higher grade slips having significantly greater APS values. Increased APS values were seen with Loder “unstable” slips. Seven hips (4.8%) developed AVN, and in these cases the APS was significantly larger than those who did not (8.5 ± 1.4 Vs 3.9 ± 1.7; p < 0.001). Receiver operator curve analysis demonstrated a critical value of 7.5 mm was associated with a 100% sensitivity and 98.6% specificity for AVN. We identified some grade II/moderate slips with high APS values had similar outcomes to grade III/severe slips, and therefore suggest that APS may serve to alert the surgeon on counselling patients on the risk of developing AVN and to consider strategies to minimise the risk of AVN. ConclusionsAPS is sensitive, specific, accurate and reliable for the association with AVN in SUFE. Its values closely reflect the high AVN rates seen in acute and unstable SUFE. This risk is greatest if the magnitude of APS exceeds the critical value of 7.5 mm.

Severity of Unconstrained Simultaneous Bilateral Slips: The Impact of Frontal Plane Feet Velocities Relative to the Center of Mass to Classify Slip-Related Falls and Recoveries.

Targeted interventions to prevent slip-related falls may be informed by specific kinematic factors measured during the reactive response that accurately discriminate recoveries from falls. But reactive responses to diverse slipping conditions during unconstrained simultaneous bilateral slips, which are closely related to real-world slips, are currently unknown. It is challenging to identify these critical kinematic factors due to the wide variety of upper and lower body postural deviations that occur following the slip, which affect stability in both the sagittal and frontal planes. To explore the utility of kinematic measurements from each vertical plane to discriminate slip-related falls from recoveries, we compared the accuracy of four Linear Discriminant Analysis models informed by predetermined sagittal or frontal plane measurements from the lower body (feet velocities relative to the center of mass) or upper body (angular momentum of trunk and arms) during reactive responses after slip initiation. Unconstrained bilateral slips during over-ground walking were repeatedly administered using a wearable device to 10 younger (24.7 ± 3.2 years) and 10 older (72.4 ± 3.9 years) adults while whole-body kinematics were measured using motion capture. Falls (n = 20) and recoveries (n = 40) were classified by thresholding the dynamic tension forces measured in an overhead harness support system and verified through video observation. Frontal plane measurements of the peak feet velocities relative to the center of mass provided the best classification (classification accuracy = 73.3%), followed by sagittal plane measurements (classification accuracy = 68.3%). Measurements from the lower body resulted in higher accuracy models than those from the upper body, but the accuracy of all models was generally low compared to the null accuracy of 66.7% (i.e., predicting all trials as recoveries). Future work should investigate novel models that include potential interactions between kinematic factors. The performance of lower limb kinematics in the frontal plane in classifying slip-related falls demonstrates the importance of administering unconstrained slips and measuring kinematics outside the sagittal plane.

The 2021 Mw 7.4 Madoi Earthquake: An Archetype Bilateral Slip‐Pulse Rupture Arrested at a Splay Fault

AbstractWe combine measurements of ground deformation from Synthetic Aperture Radar images, high‐rate Global Navigation Satellite System and tele‐seismic waveforms to study the rupture kinematics of the Madoi Earthquake, which occurred in eastern Tibet on 21 May 2021 and reached a moment magnitude Mw 7.4. The data show nearly pure left‐lateral motion along a 170 km long rupture and a total duration of 36 s. The earthquake initiated near the middle of the main segment and evolved in a bilateral slip pulse rupture which propagated at a sub‐Rayleigh speed of 2.6–2.8 km/s. In our model, slip is concentrated at depth of less than ∼15 km and reaches a maximum of 4.2 m. The rupture arrested ∼10 s after branching on the extensional splay faults at both extremities. The branching onto the splay faults and the eventual arrest of the rupture is used to provide constraints on the fault frictional properties.

The S Sign: A New Radiographic Tool to Aid in the Diagnosis of Slipped Capital Femoral Epiphysis

BackgroundChildren with slipped capital femoral epiphysis (SCFE) are often seen by an array of medical professionals prior to diagnosis. Patients with mild slips, slips with knee pain, or bilateral slips can occasionally present a diagnostic challenge that increases the risk of a delay in diagnosis and associated complications. ObjectivesThis study introduces a new radiographic parameter, which we refer to as the S-sign, and analyzes its diagnostic utility on a frog-leg lateral radiograph. MethodsTwenty observers reviewed the radiographs from 35 patients with SCFE using Klein's line on anteroposterior pelvis radiographs and the S-sign on frog-leg lateral radiographs to diagnose an SCFE. Analysis included diagnostic outcomes and intraobserver and interobserver reliability. ResultsThe S-sign was more accurate at identifying an SCFE compared with Klein's line (92.4% vs. 79.2%, respectively). Sensitivity and specificity was greater for the S-sign compared with Klein's line (89.0% and 95.2% vs. 68.3% and 89.0%, respectively). A combination of the S-sign and Klein's line yielded a sensitivity of 96.5% and a specificity of 85.0%. The combination of tests was more diagnostic for an SCFE, compared with using the Klein's line, which was statistically significant (p < 0.001). ConclusionsWith increased awareness of the S-sign and a usage of the combined test, clinicians can more reliably and accurately diagnose an SCFE. Clinicians are more likely to diagnose an SCFE using the combined test, compared with solely relying on Klein's line, which we found to be statistically significant.

Bilateral muscular slips between superior and inferior rectus muscles: case report with discussion on classification of accessory rectus muscles within the orbit

Accessory rectus muscles have rarely been reported as muscular ‘bands’ or ‘slips’ originating from the common tendinous ring (annulus of Zinn) and inserting in atypical location. This group of muscles is innervated by the inferior branch of the oculomotor nerve, lies on lateral side of the optic nerve and inserts in rectus muscles. Since there are only few descriptions of such unusual findings in the medical literature, the anatomical data on accessory rectus muscles is limited. Furthermore, existing reports vary in terms of studied objects (cadavers or living subjects), medical history (absence or presence of ocular movement disorders or eye movement abnormalities) and details of anatomical description. This report complements earlier publications and provides complete anatomical description of the accessory rectus muscle observed bilaterally during the dissection of a 68-year-old male cadaver with no eye movement abnormalities reported in the medical history. The accessory rectus muscle was divided into two ‘slips’ or ‘heads’—superior and inferior—running in the sagittal plane (laterally to the optic nerve and the main trunk of the ophthalmic artery) and attached to the superior and inferior rectus muscles. Noticeable thickening of both superior and inferior rectus muscles at the insertion point of the accessory muscle heads was observed only in the sagittal plane. On both sides, the inferior head of the accessory rectus muscle was innervated by one of sub-branches derived from the inferior branch of the oculomotor nerve. No sub-branches to the superior head were macroscopically observed during the dissection. The classification, embryological background and clinical relevance of this variation have been discussed.

Association between body mass index-for-age and slipped capital femoral epiphysis: the long-term risk for subsequent slip in patients followed until physeal closure.

BackgroundChildren who present with idiopathic slipped capital femoral epiphysis (SCFE) have an increased risk of developing bilateral disease. Predicting which patients will develop problems with bilateral hips is important for determining treatment algorithms. This is a retrospective observational study that evaluates the relationship and risk between body mass index (BMI)-for-age and unilateral and bilateral SCFE in patients followed until physeal closure.MethodsThis is a retrospective study of all patients with SCFE presenting to one institution from 1998–2005. Using the Center for Disease Control (CDC) references, BMI-for-age was calculated for each patient. The patients were followed up until complete closure of the bilateral proximal femoral physes, which was considered completion of the study. Statistical analysis for significant differences between groups was performed using the Kruskal–Wallis test for equality of populations. A logistic regression, controlling for age and gender, was used to identify BMI-for-age as a risk factor and to determine the significance of the odds ratios (ORs) for the relevant categorical variables—obese, overweight and healthy weight.ResultsEighty patients (56 male, 24 female) presented to a single institution between 1998 and 2005 with a diagnosis of SCFE. The mean age of patients was 12.2 years at initial presentation (range 8.5–16). Forty-eight patients (32 male, 16 female) presented with unilateral SCFE, with 22 of the 48 patients having a BMI for-age percentile ≥95 %. Thirty-two patients (24 male, 8 female) presented with bilateral SCFE, with 29 of the 32 patients having a BMI-for-age percentile ≥95 %. Patients with a BMI-for-age ≥95 % had a significantly increased risk of presentation with bilateral slips (OR 4.83; relative risk [RR] 3.01; p < 0.05]. All but one patient in this study with bilateral SCFE or unilateral SCFE with subsequent contralateral involvement had a BMI-for-age ≥85 % (44 out of 45 patients). Additionally, the overall risk of developing bilateral SCFE until physeal closure with a BMI-for-age ≥95 % was significantly increased (OR 3.84; RR 2.02; p < 0.05; number needed to treat [NNT] 3.01).ConclusionsPrevious work has established a relationship between BMI and SCFE. The CDC BMI-for-age growth charts more accurately measure obesity in the pediatric population compared to BMI and are therefore a more appropriate reference tool. This study demonstrates an association between obesity measured by BMI-for-age percentiles and SCFE. This study also demonstrates an association between BMI-for-age and risk for bilateral SCFE at presentation as well as overall incidence of developing bilateral SCFE in the obese pediatric population. By defining the at-risk population through BMI-for-age, physicians can screen the pediatric patient population and provide early strategies for therapeutic weight loss which may reduce the incidence of SCFE.

2A2-W02 振動子による滑り覚提示可能なバイラテラル操縦システム

2A2-W02 振動子による滑り覚提示可能なバイラテラル操縦システム

Bilateral traumatic distal femoral physeal slips: A very rare case presentation

Introduction: salter–Harris type 1 injuries of distal femur are very rare accounting for a mere 7.7% of all distal femoral injuries. No report of bilateral slips in otherwise normal child has been ever reported. case report: We herein present a case of a six-year-old boy with one month old trauma that caused bilateral distal femoral physeal slips. Patient was managed conservatively to avoid any further physeal damage. the slips healed completely with excellent range of motion. Due to late presentation, the fracture was already in stage of healing and was not frankly mobile and therefore open reduction or closed manipulation of physis was not possible without causing additional injury to growth plate. therefore, slips were managed conservatively. conclusion: this case presents a number of unique features. salter– Harris type 1 injury is uncommon in the age group presented in our case. secondly, bilateral distal femoral slips in otherwise normal child have never been reported. thirdly, it further shows that remodeling of slips presenting late is possible if the physeal damage is prevented and

Posterior Sloping Angle as a Predictor of Contralateral Slip in Slipped Capital Femoral Epiphysis

Slipped capital femoral epiphysis is a condition with potentially severe complications. Controversy remains as to when to undertake prophylactic pinning. We aimed to assess the utility of the posterior sloping angle as a predictor for contralateral slip in a large, multi-ethnic cohort including Polynesian children with a high incidence of slipped capital femoral epiphysis. All patients presenting to our hospital between 2000 and 2009 were identified and records were reviewed to determine demographic data and determine whether they subsequently developed a contralateral slip. The presenting radiographs were reviewed and the posterior sloping angle was measured. Patients with bilateral slips at presentation and those without initial radiographs were excluded. Records and radiographs of 132 patients were analyzed for the posterior sloping angle in the unaffected hip. Forty-two patients who had subsequently developed a contralateral slip had a mean posterior sloping angle (and standard deviation) of 17.2° ± 5.6°, which was significantly higher (p < 0.001) than that of 10.8° ± 4.2° for the ninety patients who had had a unilateral slip. Children who had developed a subsequent contralateral slip were significantly younger (11.1 years) than those who had developed a unilateral slip (12.2 years) (p < 0.001). If a posterior sloping angle of 14° were used as an indication for prophylactic fixation in this population, thirty-five (83.3%) of forty-two contralateral slips would have been prevented, and nineteen (21.1%) of ninety hips would have been pinned unnecessarily. The number needed to treat to prevent one subsequent contralateral slip is 1.79. To our knowledge, this is the largest study to date that confirms that the posterior sloping angle is a reliable predictor of contralateral slip and can be used to guide prophylactic pinning. The posterior sloping angle is applicable in the high-risk Polynesian population and could be useful in preventing future slips in populations that are difficult to follow up.

Two types of slip-induced falls among community dwelling older adults

Little is known about the landing behavior of the trailing (recovery) foot and ensuing types of falls following a forward slip in walking. The purposes of this study were to (1) determine if community-dwelling older adults experienced bilateral slips at the same rate as had been previously observed for young adults during over-ground walking; (2) determine if fall rate in older adults was dependent on slip type (unilateral vs. bilateral); and (3) identify differences in spatiotemporal variables of the trailing leg step between unilateral and bilateral slips. One-hundred-seventy-four participants experienced an unannounced, unrehearsed slip while walking on a 7-m walkway. Each trial was monitored with a motion capture system and bilateral ground reaction force plates. Although the experimental design, developed with original data from a young adult population, favored bilateral slips, more older adults (35%) than anticipated (10% previously observed in young, p<0.001) displayed a unilateral slip. The probability of fall was equal in the two types of slips. Eighty-two people recovered from the slip, while the remaining 92 (53%) fell. These 92 were classified into two exclusive categories based on the heel distance at the time of fall arrest using cluster analysis: those which resembled a fall into a “splits” position (n=47) or a feet-forward fall (n=45). All (100%) unilateral slips led to splits falls, as expected. Yet, not all bilateral slips (only 83%) resulted in feet-forward falls. A longer forward recovery step with a prolonged step time led to both feet slipping, nearly together, hence a feet-forward fall.

Bilateral Unstable Slipped Capital Femoral Epiphysis: A Look at Risk Factors

Unstable slipped capital femoral epiphysis can have disastrous complications including osteonecrosis and chondrolysis. It has been shown that 20% to 80% of patients may develop a contralateral slip ≤18 months after diagnosis. The purpose of this article is to report and characterize patients who developed bilateral unstable slips. After Institutional Review Board approval, the patients included were only those with bilateral unstable slipped capital femoral epiphyses. A minimum 2-year follow-up was required. Seven patients, all female, were included in the study, with an average age of 11.4 years at the time of their first slips. The interval between slips averaged 127 days (range, 0-245 days). All but 1 patient presented with a severe slip. The second slip was also severe in 3 patients and less severe in 4 patients. The triradiate cartilage was open in 3 patients. Two patients required corrective osteotomies. Chondrolysis developed in 2 patients with no osteonecrosis reported. The incidence of bilateral unstable slips ranged from 4% to 20% of all unstable slipped capital femoral epiphyses based on our findings. Skeletal immaturity was not a risk factor. The surgeon must be vigilant for the possibility of bilateral slips. The family must be instructed on precautions patients must take while recuperating from unstable slipped capital femoral epiphyses. Contralateral fixation of the unaffected side may be warranted in patients with initial severe unstable slipped capital femoral epiphyses to prevent this condition.

In situ fixation of slipped capital femoral epiphysis with Steinmann pins

Background and purpose Slipped capital femoral epiphysis (SCFE) is often treated by surgical fixation; however, no agreement exists regarding technique. We analyzed the outcome of in situ fixation with Steinmann pins.Patients and methods All 67 subjects operated for slipped capital femoral epiphysis at Haukeland University Hospital during the period 1990–2007 were included. All were treated by in situ fixation with 2 or 3 parallel Steinmann pins (8 mm threads at the medial end). The follow-up evaluation consisted of clinical examination and hip radiographs. Radiographic outcome was based on measurements of slip progression, growth of the femoral neck, leg length discrepancy, and signs of avascular necrosis and chondrolysis.Results 67 subjects (41 males) were operated due to unilateral slips (n = 47) or bilateral slips (n = 20). Mean age at time of diagnosis was 13 (7.2–16) years. Mean age at follow-up was 19 (14–30) years, with a mean postoperative interval of 6.0 (2–16) years. The operated femoral neck was 9% longer at skeletal maturity than at surgery, indicating continued growth of the femoral neck. At skeletal maturity, 12 subjects had radiographic features suggestive of a previous asymptomatic slip of the contralateral hip. The total number of bilateral cases of SCFE was 32, i.e half of the children had bilateral SCFE. 3 subjects required additional surgery and mild avascular necrosis of the femoral head was seen in 1 patient. None had slip progression or chondrolysis.Interpretation In situ pinning of SCFE with partly threaded Steinmann pins appears to be a feasible and safe method, with few complications. The technique allows further growth of the femoral neck.

Demographic Predictors of Severity of Stable Slipped Capital Femoral Epiphyses

The outcome of stable slipped capital femoral epiphysis is directly related to the severity of the slip. If it is assumed that the slip will be less severe if it is diagnosed early, then early diagnosis should improve the prognosis. It was our purpose to determine demographic predictors of the severity of a slipped capital femoral epiphysis. A retrospective study of 243 children with a total of 328 stable slipped capital femoral epiphyses was performed. Gender, race, age, and symptom duration were noted. Slip severity was classified as mild (<30 degrees ), moderate (30 degrees to 50 degrees ), or severe (>50 degrees ). Statistical analyses included bivariate, multivariate, linear correlation, and logistic regression techniques. There were 159 boys and eighty-four girls; 149 children had unilateral and ninety-four had bilateral slipped capital femoral epiphysis. Of the bilateral slips, forty-two were simultaneous and fifty-two were sequential. The mean age (and standard deviation) was 12.6 +/- 1.8 years, the mean duration of the symptoms was 5.2 +/- 7.4 months, and the mean slip angle was 29 degrees +/- 20 degrees . There were 199 mild, sixty-eight moderate, and forty-five severe slips. The mean duration of symptoms was 3.5 +/- 5.0 months for the mild slips, 7.7 +/- 9.0 months for the moderate slips, and 8.8 +/- 10.6 months for the severe slips (p < 0.0001). Older children had more severe slips: the average age was 12.3 +/- 1.8 years for the children with a mild slip, 13.0 +/- 1.6 years for those with a moderate slip, and 13.8 +/- 1.8 years for those with a severe slip (p < 0.0001). Multivariate analyses demonstrated that, among the factors studied, only the age of the patient and the duration of the symptoms were associated with the slip severity. Symptom duration and patient age were used as predictors of slip severity in a logistic regression analysis, with > or =30 degrees and <30 degrees used as the categories for slip severity, older than 12.5 years old compared with 12.5 years old or younger used as the categories for age, and more than 2.0 months compared with 2.0 months or less used as the categories for symptom duration. This model predicted the probability of a slip with confidence (p < 0.0001). The odds ratios (with 95% confidence intervals) for age and symptom duration were 2.0 (1.15 to 3.53) and 4.1 (2.34 to 7.12), respectively. Thus, a child with a stable slipped capital femoral epiphysis is 2.0 times more likely to have a moderate or severe slip if he or she is older than 12.5 years of age at the time of the diagnosis and 4.1 times more likely to have a moderate or severe slip if the duration of symptoms was longer than two months. The only two known significant predictors of the severity of a slipped capital femoral epiphysis are age at diagnosis and symptom duration. For any individual child, slip severity and symptom duration are unique; in a large population, there is a general correlation between slip severity and increases in patient age and increases in the duration of symptoms.

The ontogeny of haematopoiesis in the marine teleostLeiostomus xanthurusand a comparison of the site of initial haematopoiesis withOpsanus tau

The ontogeny of haematopoiesis in the perciform fish, spotLeiostomus xanthurus, differed from that reported as the norm for fishes, as exemplified by the cypriniform zebrafishDanio rerio, and observed in the batrachoidiform oyster toadfishOpsanus tau. Erythropoiesis in spot was first evident in the head kidney of yolk‐sac larvae 3 days after hatching (DAH). No embryonic intermediate cell mass (ICM) of primitive stem cells or blood islands on the yolk were apparent within embryos. Erythrocytes were first evident in circulation near the completion of yolk absorption,c. 5 DAH, when larvae werec. 2·0 mm notochord length (LN). Erythrocyte abundance increased rapidly with larval development forc. 14 to 16 DAH, then became highly variable following changes in cardiac chamber morphology and volume. Erythrocytic haemoglobin (Hb) was not detected within whole larvae until they were 12 DAH orc. 3·1 mmLN, well after yolk and oil‐globule absorption. The Hb was not quantified until larvae were &gt;47 DAH or &gt;7 mm standard length. The delayed appearance of erythrocytes and Hb in spot was similar to that reported for other marine fishes with small embryos and larvae. In oyster toadfish, a marine teleost that exhibits large embryos and larvae, the ICM and Hb were first evident in two bilateral slips of erythropoietic tissue in the embryos,c. 5 days after fertilization. Soon thereafter, erythrocytes were evident in the heart, and peripheral and vitelline circulation. Initial haematopoiesis in oyster toadfish conformed with that described for zebrafish. While the genes that code for the development of haematopoiesis are conserved among vertebrates, gene expression lacks phylogenetic pattern among fishes and appears to conform more closely with phenotypic expression related to physiological and ecological influences of overall body size and environmental oxygen availability.

Bilaterality in slipped capital femoral epiphysis: importance of a reliable radiographic method.

One hundred patients treated for slipped capital femoral epiphysis (SCFE) were reviewed to evaluate the incidence of bilateral slipping of the epiphysis at an average follow-up time of 32 years. When the patients were examined during adolescence, repeat lateral radiographs of the hips had been obtained by the frog lateral view in 33 patients and by the standardized lateral view according to the method of Billing in 67 patients. At re-examination, 59 patients (59%) were judged to have had a previous bilateral SCFE; in 42 of these 59 patients (71%), slipping of the contralateral hip was asymptomatic. In 23 patients (23%), the diagnosis of bilateral slipping was established at primary admission, in 18 (18%) later during adolescence, and in 18 (18%) not until the patients were reexamined as adults and the primary radiographs were reviewed. The incidence of bilateral slipping was higher in patients in whom the Billing standardized lateral view was used (63%) than in patients in whom the frog lateral view was used (52%). We conclude that the incidence of bilateral slipping of the epiphysis in patients with SCFE is approximately 60% in Sweden. If repeat radiographs of the contralateral hip are obtained with the Billing standardized lateral view until physeal closure occurs, even minor slipping of the epiphysis, which is often advisable to treat, will be apparent.

The Demographics of Slipped Capital Femoral Epiphysis An International Multicenter Study

One thousand six hundred thirty children with 1993 slipped capital femoral epiphyses were reviewed; 41.2% were girls and 58.8% were boys. There were 47.5% white, 24.8% black, 16.9% Amerindian, 7.4% Indonesian-Malay, 2.1% Native Australian/Pacific Islands, and 1.3% Indo-Mediterranean children. The diseased hip was unilateral in 77.7% and bilateral in 22.3% of the children, and chronic in 85.5% and acute in 14.5% of the children. Of the unilateral slips, 40.3% involved the right hip and 59.7% the left hip. The child's weight was greater than or equal to the ninetieth percentile in 63.2% of the children. The average age for the girls and boys was 12 and 13.5 years. The age at diagnosis decreased with increasing obesity. The youngest children were the Native Australian/Pacific Island children (11.8 years) and the oldest were the white and Indo-Mediterranean children (13 years). The Indonesian-Malay and Indo-Mediterranean children were the lightest in weight, and the black children the heaviest. The Indo-Mediterranean children had the highest proportion of boys (90.5%), and the Native Australian/Pacific Island children the lowest (50%). The highest percentage of bilaterality was in the Native Australian/Pacific Island children (38.2%), and the lowest in the Amerindian children (16.5%). The relative racial frequency of slipped capital femoral epiphysis compared with the white population was 4.5 for the Polynesian, 2.2 for the black, 1.05 for the Amerindian, 0.5 for the Indonesian-Malay, and 0.1 for the Indo-Mediterranean children. In children with unilateral involvement, the age at presentation was younger for those children in whom bilateral disease later developed (12 versus 12.9 years old). In 82% of the children with sequential bilateral slips, the second slip was diagnosed within 18 months of the first slip.

Intersonic Bilateral Slip

SUMMARY Symmetric bilateral slip at constant intersonic velocity is investigated. Linear isotropic elasticity is assumed, and the idealization of a point-sized process region is adopted. The energy release rate is calculated for a slip propagation velocity equal to lh times the S-wave speed, which is the intersonic velocity for which stresses and strains are square-root singular in this idealization. The result shows a smaller energy release rate than at low subRayleigh velocities, but in general not much smaller: it equals approximately the energy release rate at about 95 per cent of the Rayleigh wave velocity for Poisson's ratio around 0.25. For other intersonic velocities the results were modified to include a finite process region, by using previously obtained results concerning steady-state propagation. In this way the energy flow to the process region can be obtained as a function of the slip propagation velocity in the whole intersonic region for each set of process region characteristics assumed. Numerical calculations, assuming a Barenblatt process region model, indicate little sensitivity to process region size and a somewhat flat maximum close to fi times the S-wave speed.

The contralateral hip in patients primarily treated for unilateral slipped upper femoral epiphysis. Long-term follow-up of 61 hips

We reviewed, at an average age of 46 years, a series of 61 patients treated for unilateral slipped upper femoral epiphysis. At maturity there had been slipping of the contralateral hip in 11 patients (18%) and another 14 (23%) had originally had evidence of bilateral slipping when the primary radiographs were reviewed. In only two of these 25 patients (8%) was the slipping of the contralateral hip symptomatic. The incidence of early osteoarthritis of the contralateral hip was 7 of 36 with no slip, 5 of 16 with an untreated slip and 1 of 9 with a slip pinned in situ. If all 61 contralateral hips had been prophylactically pinned at the primary admission, 36 of the operations (59%) would have been unnecessary. We recommend that prophylactic pinning of the contralateral hip should not be standard, but that lateral radiography by the Billing technique be repeated every third to fourth month until closure of the growth plate begins. Hips in which a slip occurs should be pinned in situ.

Review of Slipped Capital Femoral Epiphysis Associated with Endocrine Disease

Review of type and bilaterality of 131 cases (40 bilateral) of slipped capital femoral epiphysis (SCFE) in patients with known endocrinopathies (hypothyroidism, panhypopituitarism, hypogonadism) from 1960 to 1990 showed an increased frequency of patients with endocrine disorders, primarily hypothyroidism (nine of 131 patients, 6.9%); three had bilateral slips; six developed bilateral slips in an average of 11.17 months. Delayed growth plate closure is common in SCFE. Because hypothyroidism can be easily overlooked, all patients with SCFE should be screened for hypothyroidism by measuring serum T4 and TSH (such screening is inexpensive (r = $60). Pituitary deficiency should be considered in children short for their age who have hypogonadism. Any child with a unilateral slip and one of these endocrine deficiencies has a high risk of subsequent bilateral involvement. Prophylactic pinning of the uninvolved hip is recommended because 100% of our patients eventually had bilateral slips.

The epidemiology of bilateral slipped capital femoral epiphysis. A study of children in Michigan.

The records of 224 children who had a slipped capital femoral epiphysis and who had no underlying metabolic or endocrine disorder were studied retrospectively to investigate the epidemiology of bilateral slipped capital femoral epiphysis. Eighty-two (37 per cent) of the 224 children (fifty-one boys and thirty-one girls) had a bilateral slip. Sixty-four of these children were black and eighteen were white. The age at the time of the diagnosis of the first slip was 13 +/- 1.7 years (mean and standard deviation), the duration of the symptoms was 5 +/- 5.0 months, and the angle of the slip was 26 +/- 16 degrees. Obese children were younger at the time of the diagnosis of the first slip (12 +/- 1.6 compared with 13 +/- 1.6 years for the children who were not obese, p = 0.001). The diagnosis of a slipped capital femoral epiphysis was made simultaneously in both hips in forty-one children and sequentially in forty-one children. Compared with the children in whom both hips were diagnosed simultaneously, the children in whom the hips were diagnosed sequentially had had a shorter duration of the symptoms before the diagnosis of the first slip (3 +/- 2.4 compared with 7 +/- 5.9 months, p = 0.0003), were younger at the time of the diagnosis of the first slip (12 +/- 1.9 compared with 13 +/- 1.2 years, p = 0.001), and tended to be more obese (p = 0.025). In 88 per cent of the patients who had sequential slips, the second slip was diagnosed within eighteen months after the diagnosis of the first slip.(ABSTRACT TRUNCATED AT 250 WORDS)