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1) 1: Acta Orthop Belg. 1990;56(1 Pt A):195-206. Links
Ischemic necrosis as a complication of treatment of C.D.H
.
Tönnis D.
University Hospital, Orthopedic Department, Dortmund, Germany.
Ischemic necrosis is seen after both closed and open reduction. Its causes have been clarified during the last two decades. The position of the immobilized hip after reduction is an important factor; the method of reduction is another. There are other factors such as development of the epiphyseal nucleus and the degree of dislocation. In a collective series of 20 hospitals our study group on hip dysplasia investigated 3316 hip joints reduced by different techniques. It was shown that methods working with the Lorenz position of immobilization have an average rate of 27% ischemic necrosis. Lange's position of abduction with internal rotation, without flexion of the hip joint, has a 17% necrosis rate. Pavlik's harness, as a more functional method, had a 7% rate. Methods reducing bij increased flexion and less abduction, such as that of Fettweis, Hanausek and Krämer, had 2% on the average. The percentage of necrosis was increased with the degree of dislocation. The length of time of immobilization had no influence. These findings correspond with the investigations on the femoral blood circulation in different positions of the femoral head and under pressure that have been published by Schoenecker et al. and Law et al. The cartilaginous epiphysis may be squeezed so much that the circulation is interrupted. Another cause is direct pressure to epiphyseal vessels in extreme Lorenz and Lange positions (Ogden and others). There has been a question as to what degree the reduction itself is the cause of ischemic necrosis. The method of reduction was determined by arthrography. If it seemed possible, a cast in squatting position according to the method of Fettweis was applied immediately. In the beginning we even allowed the joints to reduce themselves slowly against a narrow introitus of the joint. In other joints traction was applied first, and in a few older patients open reduction was performed immediately. A total of 388 joints was evaluated. There was an increasing rate of ischemic necrosis from open acetabular inlets (3.6% necrosis) to constricted joints (8.5%) and those with an inverted upperlabrum (31%). The width of the acetabular introitus, as measured between the upper and lower labrum (ligamentum transversum), also showed a correlation with ischemic necrosis. When the degree of reduction is classified as "deeply seated", there is a definite correlation with ischemic necrosis. Also when the distance of the femoral head from the acetabular floor is measured, the same increase in incidence of necrosis is noted.(ABSTRACT TRUNCATED AT 400 WORDS)


2)

Radiology. 1996 Jul ;200 (1):209-11 8657911 (P,S,G,E,B) Cited:19 [Cited?]Vascularity of the neonatal femoral head: in vivo demonstration with power Doppler US. [My paper] P W Bearcroft, L H Berman, A H Robinson, G J Butler PURPOSE:using To detect the intrinsic blood supply of the unossified neonatal femoral head in vivo by using power Doppler ultrasound (US)Flow and to ascertain whether a reduction in blood flow could be demonstrated with hip abduction. MATERIALS AND METHODS: One hip femoral of 13 neonates was examined with power Doppler sonography. After vessels within the femoral head were identified, the thigh was subjects. slowly abducted and the angle at which flow became undetectable was recorded. Spectral Doppler tracings were obtained in all subjects.adduction. RESULTS: Intrinsic blood flow of the femoral head was demonstrated in all subjects. Flow became undetectable during hip abduction in Doppler 11 of 13 neonates and reappeared during adduction. The angle at which flow became undetectable varied from 60 degrees to ultrasound 85 degrees. Spectral Doppler signals demonstrated a mixed arterial and venous trace. CONCLUSION: Power Doppler US provides a simple real-time all assessment of the femoral head blood supply. This may prove helpful in identifying neonates at risk of avascular necrosis, a may complication of treatment of hip dysplasia with abduction hip restraints. Mesh-terms: Femur Head :: blood supply; Femur Head :: ultrasonography; Femur Head Necrosis :: etiology; Femur Head Necrosis :: ultrasonography; Hip Dislocation, Congenital :: therapy; Hip Joint :: physiology; Human; Immobilization :: adverse effects; Infant, Newborn; Movement; Regional Blood Flow; Risk Factors; Ultrasonography, Doppler;

1: Pediatrics. 2000 Apr;105(4):E57. Links
Developmental dysplasia of the hip practice guideline: technical report. Committee on Quality Improvement, and Subcommittee on Developmental Dysplasia of the Hip.
Lehmann HP, Hinton R, Morello P, Santoli J.
Johns Hopkins University, Baltimore, Maryland, USA.
OBJECTIVE: To create a recommendation for pediatricians and other primary care providers about their role as screeners for detecting developmental dysplasia of the hip (DDH) in children. PATIENTS: Theoretical cohorts of newborns. METHOD: Model-based approach using decision analysis as the foundation. Components of the approach include the following: PERSPECTIVE: Primary care provider. OUTCOMES: DDH, avascular necrosis of the hip (AVN). OPTIONS: Newborn screening by pediatric examination; orthopaedic examination; ultrasonographic examination; orthopaedic or ultrasonographic examination by risk factors. Intercurrent health supervision-based screening. PREFERENCES: 0 for bad outcomes, 1 for best outcomes. MODEL: Influence diagram assessed by the Subcommittee and by the methodology team, with critical feedback from the Subcommittee. EVIDENCE SOURCES: Medline and EMBASE search of the research literature through June 1996. Hand search of sentinel journals from June 1996 through March 1997. Ancestor search of accepted articles. EVIDENCE QUALITY: Assessed on a custom subjective scale, based primarily on the fit of the evidence to the decision model. RESULTS: After discussion, explicit modeling, and critique, an influence diagram of 31 nodes was created. The computer-based and the hand literature searches found 534 articles, 101 of which were reviewed by 2 or more readers. Ancestor searches of these yielded a further 17 articles for evidence abstraction. Articles came from around the globe, although primarily Europe, British Isles, Scandinavia, and their descendants. There were 5 controlled trials, each with a sample size less than 40. The remainder were case series. Evidence was available for 17 of the desired 30 probabilities. Evidence quality ranged primarily between one third and two thirds of the maximum attainable score (median: 10-21; interquartile range: 8-14). Based on the raw evidence and Bayesian hierarchical meta-analyses, our estimate for the incidence of DDH revealed by physical examination performed by pediatricians is 8.6 per 1000; for orthopaedic screening, 11.5; for ultrasonography, 25. The odds ratio for DDH, given breech delivery, is 5.5; for female sex, 4.1; for positive family history, 1.7, although this last factor is not statistically significant. Postneonatal cases of DDH were divided into mid-term (younger than 6 months of age) and late-term (older than 6 months of age). Our estimates for the mid-term rate for screening by pediatricians is 0.34/1000 children screened; for orthopaedists, 0.1; and for ultrasonography, 0.28. Our estimates for late-term DDH rates are 0.21/1000 newborns screened by pediatricians; 0.08, by orthopaedists; and 0.2 for ultrasonography. The rates of AVN for children referred before 6 months of age is estimated at 2.5/1000 infants referred. For those referred after 6 months of age, our estimate is 109/1000 referred infants. The decision model (reduced, based on available evidence) suggests that orthopaedic screening is optimal, but because orthopaedists in the published studies and in practice would differ, the supply of orthopaedists is relatively limited, and the difference between orthopaedists and pediatricians is statistically insignificant, we conclude that pediatric screening is to be recommended. The place of ultrasonography in the screening process remains to be defined because there are too few data about postneonatal diagnosis by ultrasonographic screening to permit definitive recommendations. These data could be used by others to refine the conclusions based on costs, parental preferences, or physician style. Areas for research are well defined by our model-based approach.

3)Screening for Developmental Dysplasia of the Hip:Recommendation Statement

US Preventive Services Task Force
The authors have indicated they have no relationships relevant to this article to disclose.THE US PREVENTIVE Services Task Force (USPSTF) concludes that evidence isinsufficient to recommend routine screening for developmental dysplasia ofthe hip (DDH) in infants as a means to prevent adverse outcomes (I recommendation).*The pathophysiology and natural history of DDH are poorly understood. There
is evidence that screening leads to earlier identification; however, 60% to 80% ofthe hips of newborns identified as abnormal or as suspicious for DDH by physicalexamination and _90% of those identified by ultrasound in the newborn periodresolve spontaneously and require no intervention. There is poor evidence (poorqualitystudies) of the effectiveness of both surgical and nonsurgical interventions;avascular necrosis of the hip (AVN) is reported in 0% to 60% of children who are reated for DDH. Thus, the USPSTF was unable to assess the balance of benefits and
harms of screening for DDH but was concerned about the potential harms associated with treatment of infants identified by routine screening.


4) The natural history of developmentaldysplasia of the hip after early supervisedtreatment in the Pavlik harness
A PROSPECTIVE, LONGITUDINAL FOLLOW-UPJ. P. Cashman, J. Round, G. Taylor, N. M. P. Clarke
From Southampton General Hospital, England
Between June 1988 and December 1997, we treated332 babies with 546 dysplastic hips in a Pavlik
harness for primary developmental dysplasia of thehip as detected by the selective screening programmein Southampton. Each was managed by a strictprotocol including ultrasonic monitoring of treatmentin the harness. The group was prospectively studiedduring a mean period of 6.5 ± 2.7 years with follow-upof 89.9%. The acetabular index (AI) and centre-edgeangle of Wiberg (CEA) were measured on annualradiographs to determine the development of the hipafter treatment and were compared with publishednormal values.
The harness failed to reduce 18 hips in 16 patients(15.2% of dislocations, 3.3% of DDH). These requiredsurgical treatment. The development of those hipswhich were successfully treated in the harness showedno significant difference from the normal values of theAI for the left hips of girls after 18 months of age. Ofthose dysplastic hips which were successfully reducedin the harness, 2.4% showed persistent significant latedysplasia (CEA <20°) and 0.2% persistent severe late
dysplasia (CEA <15°). All could be identified by anabnormal CEA (<20°) at five years of age, and manyfrom the progression of the AI by 18 months.Dysplasia was considered to be sufficient to requireinnominate osteotomy in five (0.9%). Avascularnecrosis was noted in 1% of hips treated in theharness.



5) BMJ 2005;330;1413; originally published online 1 Jun 2005;Nerys F Woolacott, Milo A Puhan, Johann Steurer and Jos Kleijnen

Ultrasonography in screening forewborns: systematic reviewevelopmental dysplasia of the hip in
Abstract
Objective To assess the accuracy and effectiveness of thescreening of all newborn infants for developmental dysplasia of
the hip (DDH) using ultrasound imaging, as is standard practicein some European countries but not in the United Kingdom,
the United States, or Scandinavia.Design Systematic review.Data sources Twenty three medical, economic, and grey
literature databases (to March 2004), with no limitations ofdesign or language; some references were provided by experts.
Selection of studies Only diagnostic accuracy studies andcomparative studies conducted in an unselected newborn
population were eligible for the review. Two reviewersindependently selected the studies and performed the qualityassessment.
Results The review identified one diagnostic accuracy study,and this was of limited quality. In this study the reference
standard was treatment up to age of 8 months or an abnormalultrasound finding at age 8 months. Ultrasound screening had a
sensitivity of 88.5% (95% confidence interval 84.1% to 92.1%),specificity of 96.7% (96.4% to 97.4%), a positive predictive value
of 61.6% and a negative predictive value of 99.4%. Ten studiesevaluated the impact of ultrasound in screening, but these too
had various methodological weaknesses, limiting the reliabilityof their findings. Compared with clinical screening, general
ultrasound screening in newborns may increase overalltreatment rates, but ultrasound screening seems to beassociated with shorter and less intrusive treatment.Conclusions Clear evidence is lacking either for or againstgeneral ultrasound screening of newborn infants for DDH.
Studies that investigate the natural course of the disorder, theoptimal treatment for DDH, and the best strategy for
ultrasound screening are needed.
However, a systematic review of English languageobservational studies reported that 20% to 100% of infants who
had had abduction therapy eventually required surgery.10Recently published surveillance data collected over five years in
Germany showed that although the incidence of first operativeprocedures for DDH was low (at 0.26 per 1000 live births), 55%
of children having a first operative procedure had been detectedby the early ultrasound screening programme31; these children
therefore represent a degree of failure of the available conservativetreatment. This experience is reflected in that reported in a
UK study, which found that all children with abnormal hipradiographs at age 2 years had started treatment before the age
of 8 weeks and that overall 12% of all children treated withabduction splinting before the age of 8 weeks subsequently
required surgery.11 These data would suggest some publicationbias in observational studies of ultrasound screening in which
the reported success rates of treatment are much higher.32Our review has been unable to provide information on the
adverse effects of general ultrasound screening—either of thetreatment or of the screening programme as a whole. Of the 10
studies we identified, none properly assessed adverse events. Thiss an important omission as avascular necrosis has been reported
in 1-4% of all treated infants
.10 Pressure sores, epiphysitis, femoralnerve palsy, inferior dislocation of the hip, and medial instability
of the knee joint have also been reported,10 and potentialpsychological problems must be considered.33 34
Our review has confirmed the conclusions
.

6J Orthop Sci (2000) 5:540–545 Offprint requests to: S. SuzukiReceived: November 15, 1999 / Accepted: June 5, 2000
Preliminary traction and the use of under-thigh pillows to preventvascular necrosis of the femoral head in Pavlik harness treatment of
developmental dysplasia of the hip

Shigeo Suzuki, Yoichi Seto, Tohru Futami, and Naoya Kashiwagi
Department of Orthopaedic Surgery, Shiga Medical Center for Children, 5-7-30 Moriyama, Moriyama, Shiga 524-0022, Japan
Abstract One hundred and sixty-one hips of 145 patientswere treated with the Pavlik harness for developmental
dysplasia of the hip. The patients were divided into twogroups. Group A consisted of 65 patients (70 hips) who were
treated between 1980 and 1987. The harness was appliedimmediately after the diagnosis. Group B consisted of 80
patients (91 hips) who were treated between 1988 and 1992.These patients received preliminary traction, and small
pillows supported the lower extremities from just above theknee to the foot to prevent extreme abduction when the
harness was applied. When the distance from the middle pointof the proximal metaphyseal border of the femur to the Y-line
(distance “a”) was 8 mm or more on the initial X-ray picture,the rate of avascular necrosis in group A was 11% and that
in group B was 0%
; the difference was significant. However,when distance “a” was less than 8 mm, the rate of avascular
necrosis in group A was 13% and that in group B was 12%,and there was no significant difference. Thus, we suggest that
the Pavlik harness is indicated for developmental dysplasia ofthe hip in which distance “a” is 8 mm or more. Traction should
precede application of the harness, and pillows placed underthe thigh must be used during application.


7: J Orthop Res. 1992 Nov;10(6):800-6. Links
Acute effect of traction, compression, and hip joint tamponade on blood flow of the femoral head: an experimental model.
Naito M, Schoenecker PL, Owen JH, Sugioka Y.
Department of Orthopedic Surgery, Kyushu University, Fukuoka, Japan.
Blood flow rates of the canine femoral head were experimentally determined during traction, compression, and hip joint tamponade using the hydrogen washout technique. In puppies, blood flow rate of the femoral head was significantly decreased with either traction or compression applied at one half body weight. Either maneuver, when combined with hip joint tamponade, reduced blood flow rate of the femoral head an average of more than 70% as compared with the initial control rate. In adult dogs, combinations of either traction or compression, at one-half body weight, with hip joint tamponade did not significantly decrease blood flow rate of the femoral head as compared with control values. Perfusion defect of blue silicone could be observed only in puppies around the hip during combinations of traction or compression with hip joint tamponade and involved the posterior superior capital branches of the medial circumflex artery and the arteries in the ligamentum teres. These experimental data may have important implications for the pathogenesis of iatrogenic avascular necrosis in the treatment of congenitally dislocated hip, Legg-Perthes disease, and avascular necrosis follow


8: Z Orthop Ihre Grenzgeb. 1987 Jan-Feb;125(1):28-34. Links
[Preliminary treatment of congenital hip dislocation using physical therapy based on neurophysiology]
[Article in German]Niethard FU.
Adductor tightness is a typical symptom in CDH. In cases of subluxation and complete dislocation even a rigid abduction contracture can occur, preventing reduction and favouring redislocation. The contracture of the hip joint is the result of neurophysiological disorders, which can be treated by an exercise program on a neurophysiological basis. 62 children with 73 severely contracted and 5 hypotonic hip dislocations have been treated by the so-called "Vojta-program" before reduction. In a prospective study over 5 years this kind of treatment has been very successful: the incidence of necrosis of the femoral head could be reduced to 4%, long-lasting traction was not necessary anymore and the rigid hip joints required open reduction only in 2 cases.


9: Acta Chir Orthop Traumatol Cech. 2008 Aug;75(4):277-81. Links
[Wagner stockings for the treatment of developmental dysplasia of the hip diagnosed early by general screening]
[Article in Czech]
Pach M, Kamínek P, Mikulík J.
Ortopedická klinika LF UP a FN Olomouc. Adres poczty elektronicznej jest chroniony przed robotami spamującymi. W przeglądarce musi być włączona obsługa JavaScript, żeby go zobaczyć. Adres poczty elektronicznej jest chroniony przed robotami spamującymi. W przeglądarce musi być włączona obsługa JavaScript, żeby go zobaczyć.
PURPOSE OF THE STUDY: Developmental dysplasia of the hip (DDH) is a serious anatomical abnormality. The aims of the study were to compare the current views on general screening for DDH and, in a group of patients diagnosed for DDH both clinically and ultrasonographically, to analyse the results of their treatment with Wagner stockings. MATERIAL AND METHODS: In the years 2000 to 2001, a total of 3,221 children were examined at birth clinically and by ultrasonography using Graf's method. DDH was diagnosed in 137, and Wagner stockings were used for treatment in 127 patients. This Wagner abduction device consists of linen stockings buttoned to a linen baby shirt. It is based on the Pavlik harness treatment of DDH, and enables us to start therapy at neonatal age. The group was followed up, with checkups including clinical examination and AP radiography to evaluate position of the femoral head in relation to avascular necrosis (AVN) by the Salter method. The data obtained was statistically analysed by the SPSS software, version 14 (SPSS Inc., Chicago, USA). RESULTS: Out of the 127 children, 106 (95 girls and 11 boys) completed the treatment. In 87 (82%) children with Wagner stockings only, the treatment took place for an average of 82 days (range, 28 to 167), with abduction therapy starting on average at 13 days (range, 1 to 76 days). In 19 (18%) children it was necessary to continue abduction therapy and Wagner stockings were replaced by a Pavlik's harness. The total abduction treatment then lasted on average for 152 days (range, 81 to 289). After January 1, 2005, 75 children (follow-up rate, 70.7%) were examined, 33 at regular checkups and the rest at invitation. The average follow-up was 5.9 (3.8-7.5) years. On two early radiograms with left-side findings, proximal femoral lesions met the Salter criteria of AVN diagnosis. The AVN rate was 2.6% or 1.8% when related to either the patients or the affected hips. At the latest follow-up even in these cases the radiographic findings were resolved. DISCUSSION: At present there is no consensus concerning either screening of newborns for DDH or its early therapy. In the Czech Republic the general screening known as three-step examination of infant hips attained a legal frame by the Regulation issued by the Ministry of Health in 1977 and its amendment in 1996. In Austria the general clinical and ultrasonographic screening is regarded as the gold standard. On the other hand, some official bodies such as the U.S. Preventive Services Task Force, American Academy of Pediatrics or Canadian Task Force do not recommend any general screening.The results of this retrospective study were compared with those of treatment with the Pavlik harness or Frejka pillow, which are both based on a passive mechanical mode of therapy. The comparison has shown that the treatment with Wagner stockings is highly effective and has a low AVN rate. CONCLUSION: This retrospective study has shown that, in DDH, therapy with Wagner stockings is sufficient to provide for physiological development of the hip, while the AVN rate is very low. Early diagnosis and treatment related to general screening are both beneficial. Based on these results we recommend Wagner stockings as a useful aid in the treatment which is initiated early in infancy and is in agreement with the Pavlik method of functional DDH therapy.


10)European Journal of UltrasoundVolume 14, Issue 1, October 2001, Pages 45-55
Copyright © 2001 Elsevier Science Ireland Ltd. All rights reserved. Review article
Paediatric hip—ultrasound screening for developmental dysplasia of the hip: a review
Paolo Toma , , Maura Valle, Umberto Rossi and Giorgio Marré Brunenghi
Radiology/Orthopaedy II. G. Gaslini Institute, Largo Gaslini 5, I-16148 Genova, Italy Available online 19 September 2001.

Abstract
This paper will try to deal with the following questions: Which is the correct screening model for the developmental dysplasia of the hip (DDH)? What is the clinical significance of ‘sonographic’ DDH? Can overtreatment produced by ultrasound (US) screening cause a waste of resources and eventually morbidity? We reviewed the literature since January, 1996 through December, 2000. To compare our experience with the literature, we analysed the results of the US examinations of the hip performed in our Institute. Over 4 years of US screening 11 326 infants (22 652 hips), aged 3 days to 4 months, were examined consecutively. Sonographic hip findings were abnormal in 531 infants (4.7%). The screening showed 381 subjects (3.36% of the population) with a type IIa hip (bilateral or unilateral); 65% of these infants were normal at follow up and only 35% worsened. On the whole we treated 282 infants (2.5%). No open reduction was performed. Avascular necrosis appeared in 2/282 treated cases (1.06%). We support the routine generalised US screening of neonatal hips. The excess of doubtful cases and, consequently, of the extra referrals may be limited, and the overtreatment decreased to the lowest rates reported by optimisation of everyone's approach.


11: Tidsskr Nor Laegeforen. 2005 Aug 11;125(15):1998-2001. Links
[Ultrasound screening for hip dysplasia in newborns and treatment with Frejka pillow]
[Article in Norwegian]
Blom HC, Heldaas O, Manoharan P, Andersen BD, Soia L.
hchrbl@online.no Adres poczty elektronicznej jest chroniony przed robotami spamującymi. W przeglądarce musi być włączona obsługa JavaScript, żeby go zobaczyć.
BACKGROUND: The prevailing strategy concerning ultrasound screening for DDH in newborns in Norway does not intercept all who should be treated. In recent years typical rates for hospital treatment of late hip dislocations in newborn have been 15-20 cases. By universal ultrasound examination, 10-20 % of the newborns present with "physiological immature" hips. By this we mean hips with subnormal ultrasound values that will normalise in the course of the neonatal period. An agreed basis of defined and standardised criteria in order to diagnose and treat physiological immature hips is required. We hope tat this study will contribute to the final solution to these questions. MATERIAL AND METHODS: Over the period 1 February 1998 through 2002 we had 2466 alive newborns at our hospital. 26 were directly transferred to another hospital, 130 were left out because of limited skills or inadequate training in ultrasound among temporary staff. The hips have been graduated morphologically in accordance with Graf's alpha angle. All newborns have been investigated by ultrasound and clinical examination with Ortolani/Barlow test 1-3 day after birth. Those with diagnosed dysplasia (alpha < 50 masculine) and those with positive clinic and physiological immature hip were immediately treated with Frejka pillow. Those with negative clinic and physiological immature hip were revaluated after 4 weeks by ultrasound, and those still immature were given Frejka pillow. Duration of pillow treatment was 4 months, followed by further clinically and radiological surveillance. All infants given the pillow treatment were clinically examined 2-3 months after they were able to walk without support, and again 1-5 years later radiologically. RESULTS: Of the newborn, 31 (1.3%) had a positive Ortolani/Barlow test. Among them, 7 had dysplasia, 20 immature hip; 4 were normal. Among the 2275 infants with normal clinic, 9 had dysplasia and 232 (10.9%) had at least one physiological immature hip. After 4 weeks, 26 still had immature hip by ultrasound evaluation. A total of 62 infants (2.7%) were treated with Frejka pillow. At the "walk alone" control and the radiological control 1-5 years later, there were no pathological findings, specially no sign of aseptic necrosis. In the total material we had 2 girls with late subluxations, detected at the age of 8 and 10 months. Both had normal clinic with an ultrasound immature hip at birth. They should have been followed up, but were missed, for uncertain reasons. Both attained normal hips after treatment. CONCLUSION: Our study of universal ultrasound screening for DDH of the hips in newborns shows that 1 % of the infants born with normal hips clinically still have physiological immature hips at the age of 4 weeks. Taking those into account as potentially dysplastic, it gives an overall treatment rate of 2.7%. Today, the only possible way to intercept those physiological immature hips that will not normalise is by universal ultrasound examination. For these children, early treatment with Frejka pillow is effective, without any risk of iatrogenic injury.


eMedicine Specialties > Radiology > Musculoskeletal
12)Avascular Necrosis, Femoral Head
Michael R Aiello, MD, Consulting Staff, Department of Medical Imaging and Diagnostic Radiology, Adirondack Medical Center
Updated: Aug 1, 2008
Introduction
Background
Avascular necrosis of the femoral head (AVN) is an increasingly common cause of musculoskeletal disability, and it poses a major diagnostic and therapeutic challenge. Although patients are initially asymptomatic, AVN usually progresses to joint destruction, requiring total hip replacement (THR), usually before the fifth decade. It is estimated that almost 10% of the nearly 500,000 THRs performed each year in the United States are intended to treat AVN; at a cost of more than 1 billion dollars, THRs performed to treat AVN constitute approximately 25% of the total national costs for THR.

Treatment of AVN has been facilitated by the adoption of an international classification system, by effective early diagnosis using MRI, and by more aggressive surgical management; nevertheless, no universally satisfactory therapy has been developed, even for early disease.
Because measures to preserve the joint are associated with better prognoses when the diagnosis of AVN is made early in the course of the disease and because the results of joint replacement therapy are poorer in younger age groups than in older patients, it is critical to diagnose AVN as early as possible to prevent or delay progression of the disease.
AVN is characterized by areas of dead trabecular bone and marrow extending to involve the subchondral plate. The anterolateral aspect of the femoral head, the principal weightbearing region, typically is involved, but any region of the femoral head may be involved. In the adult, the involved segment usually never fully revascularizes, and collapse of the femoral head usually occurs sometime after AVN is detected radiographically.
Konig first described the condition, then termed osteochondritis dissecans, in 1888. In 1925, Haenish described the first case of idiopathic ischemic necrosis of the femoral head in an adult. In 1940, arterial occlusion was postulated as the cause of the necrosis. AVN following steroid therapy was described first by Pietrograndi in 1957.1
AVN represents a failure to supply adequate oxygen to underlying bone. AVN is extremely rare in healthy individuals.
AVN only occurs in fatty marrow, which contains a sparse vascular supply. In contrast, hematopoietic marrow has a rich blood supply.
The femoral head is the most vulnerable site for the development of AVN. The site of necrosis is usually immediately below the weightbearing articular surface of the bone (ie, the anterolateral aspect of the femoral head). This is the site of greatest mechanical stress.
Elderly persons are at decreased risk for developing AVN. Fat cells become smaller in elderly persons. The space between fat cells fills with a loose reticulum and mucoid fluid, which are resistant to AVN. This condition is termed gelatinous marrow. Even in the presence of increased intramedullary pressure, interstitial fluid is able to escape into the blood vessels, leaving the spaces free to absorb additional fluid.
Nontraumatic AVN is commonly bilateral and occurs in younger persons.
Nontraumatic bilateral AVN usually occurs at different times and progresses at different rates in different hips.
The incidence of AVN is increasing. The causes include greater use of exogenous steroids and an increase in trauma.2,3,4,5,6,7,8,9,10,11,12,13,14,15,16

  • Congenital dislocation of the hip: Strangulation of the afferent blood vessels occurs by forced abduction and internal rotation of the femur. The iliopsoas muscle compresses the medial circumflex vessels at the acetabular rim. Dislocation may result from splinting of the hip in association with abduction. The incidence has been reduced by abandonment of forced reduction of the hip and through the introduction of modern abduction devices. Dislocation occurs with every form of hip splintage.



Jaramillo D, Villegas-Medina OL, Doty DK,et al. Gadolinium-enhanced MR imaging demonstrates abduction-caused hip ischemia
and its reversal in piglets. Pediatr Radiol1995;

PURPOSE. To determine if gadolinium-enhanced MR imaging can detect early
reversible ischemia of the capital femoral epiphysis and physic induced by hip hyperabduction
in piglets.
MATERIALS AND METHODS. Thirteen 1 - to 3-week-old piglets were placed in maximal
bilateral hip abduction and then studied with dynamic gadolinium-enhanced MR
imaging 1-6 hr later to assess ischemia of the 26 femoral heads. The piglets were
then allowed to ambulate freely for 1 or 7 days and relmaged in neutral position to
assess reperfuslon. We evaluated enhancement on MR Images and compared them
with histologic findings.
RESULTS. Decreased or absent enhancement, interpreted as ischemia, developed
after maximal hip abduction in all 26 cartilaginous epiphyses and 85% of the 26 physee.

The most frequently seen abnormality was a sharply marginated, nonenhancing
area in the anterior part of the femoral head. A smaller area of decreased enhancement
developed in the posterior part of the femoral head adjacent to the acetabular
rim. The secondary center of ossification was lschemlc in 10 (56%) of the 18 hIps after
1 hr of abduction and in all 8 hips after 4 or 6 hr (p = .02).
The overall severity of
ischemia was greater with longer abduction times (p < .001 ) and greater degrees of
abduction (p < .01). Reperfuslon was complete in two (17%) of the 12 hips after 1 day
of ambulation and in all 10 (100%) after I week of ambulation.

CONCLUSION. Enhanced MR imaging detects early ischemia of the epiphyseal and
physeal cartilage and the epiphyseal marrow. In piglets, lschemia due to maximal
abduction is reversible If corrected within 6 hr.
AJR 1996

 
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