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Hip disorders in childhood
ORTHOPAEDICS V: PAEDIATRICS
(within 72 hours), and again at 6e8 weeks of age.1 A dislocated hip typically is identified by asymmetric skin creases and a short lower limb with limited abduction. Whilst asymmetric skin creases are a useful sign of DDH they are not specific, as these may be seen in around 25% of normal neonates, and therefore in isolation are of limited use. Hip stability may be tested using two specific movements of the hips termed the Barlow and the Ortolani manoeuvres (Figure 2). The efficacy of clinical screening is debated, as it lacks sensitivity (high false-negative rate), which is problematic as diagnostic delays necessitate greater degrees of operative and nonoperative interventions. Ultrasound is a more sensitive means of hip screening but, in contrast to clinical screening, has a higher false-positive rate resulting in potential for overtreatment. Ultrasound screening can be used to screen an entire population of newborns, or focus on selected groups who are abnormal on clinical screening, or are at particularly high risk of DDH. UK centres have generally adopted the ‘selective screening’ model. The NHS screening programme advocates ultrasound at 2 weeks of age if positive newborn physical examination and by 6 weeks of age if newborn examination negative but risk factors (first-degree relative or breech 36 weeks).2 Ultrasound screening remains controversial on cost/benefit grounds and a meta-analysis of randomized controlled trials has failed to demonstrate a significant reduction in late presenting DDH. Some countries (e.g. Germany and Switzerland) continue to use a population screening approach and therefore the debate of who and how to screen continues. Some children are inevitably not identified by current screening methods and their presentation is delayed. In children over 6 months old the diagnosis may be made with a plain anteroposterior (AP) pelvic radiograph. Children of walking age usually present with an abnormal gait e the result of having a shortened limb and altered joint mechanics, leading to a positive Trendelenburg sign. Figure 3 is a radiograph demonstrating a dislocated hip on the left side in a 14-month-old girl. An arrow indicates the position of the underdeveloped ossific nucleus of the femoral head. Two lines are helpful in assessing plain radiographs. Hilgenreiner’s horizontal line (H) is drawn through the triradiate cartilage at the floor of the acetabulum on each side. Perkins perpendicular (P) line is drawn at the edge of the bony acetabular roof and perpendicular to Hilgenreiner’s line. Together the lines create a ‘cross-wire’. A normal ossific nucleus is located in the lower inner quadrant of these ‘cross-wires’. The treatment of DDH is largely dependent upon the age at which the disease is identified. A neonate in whom DDH is identified is generally successfully treated in a removable split (e.g. Pavlik harness) which is required for around 3 months. Presentation at 6 months would necessitate reduction under anaesthesia, along with 6 months in plaster trousers (spica cast). As identification is increasingly delayed treatment becomes more invasive and the short and long-term morbidity greater. Early identification and treatment of DDH is therefore important to facilitate successful treatment, and minimize patient morbidity (Figure 4).
Hip disorders in childhood Sara Dorman Daniel Perry
Abstract Childhood disorders of the hip are encountered frequently in paediatric orthopaedic practice. They present initially to paediatricians, general practitioners and accident departments, and it is therefore important for both surgeons and generalists to have a good working knowledge of the common presentations. The challenge is to distinguish between disease processes that are benign and self-limiting (e.g. transient synovitis), acute and joint threatening (e.g. septic arthritis) or chronic and disabling (e.g. Perthes’ disease). This review primarily considers the epidemiology and aetiology of childhood hip diseases and provides a diagnostic framework, based upon age and risk factors. The important investigations and treatment options for each of the key differential diagnoses are also considered.
Keywords Developmental dysplasia of the hip; irritable hip; Perthes; septic arthritis; slipped capital femoral epiphysis; transient synovitis
Introduction The hip is a common focus of pathology in children’s orthopaedic surgery. The frequency of various conditions changes at different stages in a child’s development and therefore age is the key consideration when constructing a differential diagnosis for hip pathology in children (Figure 1).
Developmental dysplasia of the hip (DDH) DDH represents a spectrum of disease ranging from a hip which is poorly centred within the acetabulum, to a hip which is completely dislocated. ‘DDH’ has replaced the old term ‘congenital dislocation of the hip’ to recognize the wide spectrum of disease encountered, beyond simply ‘dislocated hips’. DDH affects predominantly girls (80%), and is usually detected in the neonatal period. The incidence of true DDH in the UK population is approximately 1 per 1000 live births. In unilateral disease the left hip is affected three times more commonly than the right. The aetiology of DDH is both genetic and environmental. The intrauterine environment is especially relevant, as ‘packaging’ disorders due to the limited space in-utero is thought to be an important aetiological factor (Box 1). Routine clinical examination of newborn infant hips is mandatory in the UK, and must be carried out at or soon after birth
Sara Dorman MB ChB BMSc (Hons) MRCSEd is a Speciality Registrar at Alder Hey Children’s Hospital, Liverpool, UK. Conflicts of interest: none declared. Daniel Perry MB ChB (Hons) PhD FRCS (Tr&Orth) is an Honorary Consultant Orthopaedic Surgeon and Senior Lecturer at Alder Hey Children’s Hospital and University of Liverpool, UK; NIHR Clinician Scientist. Conflicts of interest: none declared.
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Septic arthritis Septic arthritis is an infection of the synovium and joint space (Figure 5). The hip is the most commonly affected joint.
1
Ó 2016 Published by Elsevier Ltd.
Please cite this article in press as: Dorman S, Perry D, Hip disorders in childhood, Surgery (2016), http://dx.doi.org/10.1016/j.mpsur.2016.10.009
ORTHOPAEDICS V: PAEDIATRICS
Timeline for hip disease in children Birth
5 years old
Developmental hip dysplasia
10 years old
Transient synovitis
15 years old
Slipped capital femoral epiphysis
Perthes’ disease Septic arthritis
Perthes’ disease Septic arthritis Septic arthritis
Figure 1
this then results in dispersion of the infection into the joint space, resulting in septic arthritis (Figure 5c). Staphylococcus aureus is the most common infecting organism in septic arthritis,3 but the clinical context must be considered when predicting likely organisms; for example group B streptococcus is common in neonates and Kingella Kingae in younger children. Typically children are unwell, febrile and with a reluctance to move or put weight through the hip. Children may be immunocompromised or otherwise unwell due to systemic sepsis and often referred from intensive care environments. Ultrasound is useful to confirm a joint effusion, and joint aspiration is the gold standard means of diagnosis, based upon the presence of pus and organisms. In cases of culture-negative septic arthritis supplemental polymerase chain reaction techniques have been reported to improve detection of bacteria within joint fluid, particularly in Kingella Kingae infection. Urgent treatment includes surgical washout and intravenous antibiotics, without which joint destruction and growth arrest may occur.
Risk factors for developmental dysplasia of the hip C
C C C C C C
Positive family history (1 first-degree relative, or 2 second degree relatives) Breech presentation 36 weeks Large for gestational age (birthweight >5 kg) Neonatal foot deformity Oligohydramnios Prematurity Fetal moulding (e.g. torticollis)
Box 1
Infection usually begins as a focus of metaphyseal osteomyelitis. Infection reaches the bone by a blood-borne bacteraemia (Figure 5a). The vascularity of the metaphysis, and the anatomy of its thin-walled blood vessel loops, is thought to facilitate bacterial spread and make the metaphysis particularly vulnerable to infection. The metaphyseal cortex is thin and easily breached to allow infection to enter the subperiosteal space to form an abscess (Figure 5b). The hip, along with several other joints (e.g. shoulder, ankle and elbow), have a metaphysis which lies intraarticular. If a subperiosteal abscess ruptures within these joints
Transient synovitis Transient synovitis is a benign joint effusion. It usually occurs in boys between 4 and 8 years old. The typical presentation is a well
Dislocate Legs held flexed and adducted Femurs axially loaded Examiner’s index finger to feel over the child’s buttocks to detect the femoral head dislocating
Ortolani manoeuvre
Barlow manoeuvre
Clinical hip screening Reduce Hips are gently abducted Examiner feels for a ‘clunk’ to indicate that a dislocated hip has relocated within the acetabulum
Figure 2
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Figure 3 A dislocated hip on the left side in a 14-month-old girl.
2
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Please cite this article in press as: Dorman S, Perry D, Hip disorders in childhood, Surgery (2016), http://dx.doi.org/10.1016/j.mpsur.2016.10.009
ORTHOPAEDICS V: PAEDIATRICS
Treatment ladder for developmental dysplasia of the hip 2.5 years and above
18 months – 2.5 years
12–18 months 3–12 months
Birth – 3 months
Open reduction and pelvic and femoral osteotomy Open reduction and pelvic osteotomy
Open reduction and plaster (6 months)
Closed reduction in theatre and plaster (6 months)
Removable splint in clinic (3 months)
Figure 4 Age at diagnosis determines the entry point on the ladder, and failure of treatment moves an individual to the next step in the ladder. Duration of a typical treatment is shown in brackets. This therefore illustrates the importance of an early diagnosis in minimizing the nature and duration of the intervention required.
child with an unexplained limp, and it is the most common cause of an atraumatic limp in infancy. The cause of transient synovitis is unknown. There is a suggestion that transient synovitis may arise secondary to a viral illness although there is little evidence to support this. Certainly no viral pathogen has been identified with any consistency. The diagnosis is based upon a proven hip effusion with the exclusion of other potential causes. The treatment of transient synovitis is rest and analgesia. Symptoms tend to subside within 2 weeks, and usually within a few days. Ongoing symptoms should prompt the clinician to reconsider their diagnosis and initiate further investigation.
resolves spontaneously. Hip aspiration under general anaesthesia is the ‘gold standard’ means of excluding septic arthritis but is not routinely performed as this would yield a large number of negative results, as transient synovitis is very much more common than septic arthritis. Algorithms exist to help to differentiate between septic arthritis and transient synovitis. The most widely known algorithm was created based upon those children with a proven hip effusion, and uses four commonly recorded parameters to assist in making a diagnosis (Table 1).4 More recent modifications of this algorithm suggest that the inclusion of C-reactive protein (CRP) simplifies the protocol even further, as only CRP (>20 mg/ litre) and not weight bearing are independent predictors of septic arthritis.5 Whilst debate continues as to the validity of these algorithms the general consensus remains that they remain the most useful tools to date.6
Septic arthritis or transient synovitis? The most significant difficulty, when faced with a child with presumed transient synovitis, is excluding septic arthritis. Septic arthritis requires urgent treatment, though transient synovitis
Development of septic arthritis
Vessels
Breached periosteum
Sub-periosteal collection
Abscess Growth plate a
Joint capsule b
c Figure 5
SURGERY --:-
3
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Please cite this article in press as: Dorman S, Perry D, Hip disorders in childhood, Surgery (2016), http://dx.doi.org/10.1016/j.mpsur.2016.10.009
ORTHOPAEDICS V: PAEDIATRICS
Algorithm for differentiating between transient synovitis and septic arthritis Factors for predicting septic arthritis C Fever >38.5 C C Non-weight bearing C Erythrocyte sedimentation rate >40 mm/hour C Serum white cell count >12 10 9 Number of factors present Probability of septic arthritis (%) 0 <0.2 1 3.0 2 40 3 93.1 4 99.6
a
Table 1
Perthes’ disease Perthes’ disease is an idiopathic avascular necrosis of a developing femoral head. It usually affects boys between 4 and 8 years old. The lifetime incidence of Perthes’ disease within the UK is approximately 1 per 1200 children.7 The typical presentation is with hip or knee pain and a limp. Children are thought to have a hyperactive tendency and be generally shorter than their peers. White children are mainly affected, Asian children rarely and black children almost never.8 The incidence also varies with social class, with the most deprived children having the highest incidence.9 The cause of Perthes’ disease is unknown. It is known that around this age a single vessel supplies the epiphysis called the ‘lateral ascending epiphyseal artery’, a branch of the ‘medial circumflex artery’. In Perthes’ disease this vessel is thought to become occluded, resulting in the necrosis of the epiphysis. The origin of the occlusion remains unknown as no extraluminal or intraluminal cause may be identified with any consistency. Recently, investigators have identified associations with parental smoking, and an elevated risk of ischaemic heart disease in middle-aged adults who suffered with Perthes’ disease as
b Figure 7 Anteroposterior and lateral radiograph demonstrating a leftsided slipped capital femoral epiphysis. Klein’s line is drawn on the plain AP radiograph along the upper border of the femoral neck. The line usually intersects the epiphysis. In an abnormal situation the line fails to intersect the epiphysis. The arrow indicates a subtle irregularity within the metaphysis called the ‘blanch sign’. The lateral projection demonstrates the slip more clearly. There is less than 1/3 displacement and therefore the slip is ‘mild’.
infants,10 and thus a common underlying pathology may be responsible. The diagnosis of Perthes’ disease is made by a plain AP radiograph of the pelvis (Figure 6). Classical radiographic features of Perthes’ disease include sclerosis, fragmentation and eventual flattening of the proximal femoral epiphysis. Treatment requires ‘containment’ of the hip within the acetabulum. This works on the assumption that the femoral epiphysis is ‘softened’ by Perthes’ disease. Containment therefore seeks to maintain the epiphysis deep within the hemispherical ‘mould’ of the acetabulum. This maintains the femoral head sphericity until it once again becomes firm e generally occurring after around 3 years. This effect can be achieved by conservative or surgical means. Conservative treatment often makes use of a brace or spica plaster to maintain the legs in abduction, while surgery repositions the femoral head or augments the acetabulum to achieve the goals of ‘containment’. Prognosis depends upon age, sex and extent of epiphyseal involvement.11
Slipped capital femoral epiphysis (SCFE) SCFE is also known as slipped upper femoral epiphysis (SUFE). An SCFE is characterized by an anterior slip of the metaphysis
Figure 6 A radiograph illustrating Perthes’ disease. The right femoral head can be seen to be flattened and more dense (sclerosis).
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4
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Please cite this article in press as: Dorman S, Perry D, Hip disorders in childhood, Surgery (2016), http://dx.doi.org/10.1016/j.mpsur.2016.10.009
ORTHOPAEDICS V: PAEDIATRICS
Overall summary Diagnosis
Lifetime incidence
Typical age of presentation (years)
Male:female ratio
Risk factors
Developmental dysplasia of the hip
1:1000 True dislocation
Neonates
1:4
Septic arthritis
1:1000
Under 3
1.5e2:1
Transient synovitis Perthes’ disease
1:400 1:1000
4e10 4e8
3:1 4:1
Slipped capital femoral epiphysis
1:1000
>10
1.5:1
Breech presentation Family history Oligohydramnios Foot deformity Concurrent disease Immunosuppression Recent viral illness Small for age Socioeconomic deprivation Obesity Endocrinopathies
Table 2
Treatment is by prompt recognition and urgent screw fixation of the slip to prevent further deterioration. In certain situations the slip may have progressed beyond the acceptable limits for fixation, and in such instances an osteotomy can be performed to realign the bones to correct the deformity and facilitate fixation. The prognosis is dependent on the development of avascular necrosis and the severity of the slip (Table 2).
relative to the epiphysis, endangering the blood supply to the epiphysis. It typically occurs above 10 years old, and affects boys 1.5 times more commonly than girls. The physis becomes particularly vulnerable to injury around puberty, which is believed to be associated with rapid growth. Several groups are at particularly high risk of SCFE. Obesity exerts high forces on the physis and this may precipitate a slip.12 Endocrine abnormalities, such as hypothyroidism and treatment with growth hormone, have a tendency to weaken the physis thereby increasing the frequency of SCFE.13 SCFEs may present with acute and sudden pain such that the patient cannot bear weight (unstable slips), or as chronic pain whereby they are still able to bear weight (stable slips).14 Pain may often be referred to the knee such that a patient presents with isolated knee pain. The most sensitive clinical sign of SCFE is pain or discomfort on internal rotation of the hip. A plain AP radiograph of the pelvis may be unremarkable if the slip is subtle. A lateral projection is more sensitive to identify such slips and is therefore essential. Klein’s line may be drawn on the radiograph to help identify the SCFE (Figure 7). SCFE is categorized radiologically into mild, moderate and severe depending on the degree of displacement of the epiphysis on the metaphysis: 0e1/3 mild 1/3e1/2 moderate > 1/2 severe. About 80% of slips are ‘stable’ at presentation, and such cases have a minimal risk of avascular necrosis. There are many reports of stable SCFEs going undetected for many months as the individual complained of ‘knee pain’ and the clinician failed to consider that this pain may be referred from the hips. Diagnostic delays worsen the outcome of stable SCFE as the femoral head progressively deforms,15 or occasionally the slip may suddenly worsen precipitating an unstable slip. Early detection through disease awareness, and considering the hip when presented with knee pain, is important to minimize patient morbidity. Unstable slips carry a poor prognosis because the slip often tears the blood supply leading to avascular necrosis in 50% of cases.
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Other considerations Most childhood hip problems are due to one of the pathologies discussed above in this review. However, other diagnoses should be considered in patients in whom symptoms, signs and investigation results do not conform to the ‘typical’ patterns. Trauma is always a consideration in any orthopaedic presentation and of particular importance in children is the possibility of nonaccidental injury. Other diseases include the inflammatory arthritides, local benign or malignant tumours and systemic disease such as childhood leukaemia. A REFERENCES 1 Standing Medical Advisory Committee and Standing Nursing and Midwifery Advisory Committee Working Party. Screening for the detection of congenital dislocation of the hip. Arch Dis Child 1986; 61: 921e6. 2 Public Health England. Newborn and Infant Physical Examination Screening Programme Handbook 2016/2017. Retrieved 31 May, 2016 from https://www.gov.uk/government/uploads/system/ uploads/attachment_data/file/524425/NIPE_Programme_ Handbook_2016_to_2017_.pdf. 3 Goergens ED, McEvoy A, Watson M, Barrett IR. Acute osteomyelitis and septic arthritis in children. J Paediatr Child Health 2005; 41: 59e62. 4 Kocher MS, Zurakowski D, Kasser JR. Differentiating between septic arthritis and transient synovitis of the hip in children: an evidence-based clinical prediction algorithm. J Bone Joint Surg Am 1999; 81: 1662e70. 5 Singhal R, Perry DC, Khan FN, et al. The use of CRP within a clinical prediction algorithm for the differentiation of septic arthritis
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Please cite this article in press as: Dorman S, Perry D, Hip disorders in childhood, Surgery (2016), http://dx.doi.org/10.1016/j.mpsur.2016.10.009
ORTHOPAEDICS V: PAEDIATRICS
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9
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and transient synovitis in children. J Bone Joint Surg Br 2011; 93: 1556e61. Taekema HC, Landham PR, Maconochie I. Towards evidence based medicine for paediatricians. Distinguishing between transient synovitis and septic arthritis in the limping child: how useful are clinical prediction tools? Arch Dis Child 2009; 94: 167e8. Perry DC, Bruce CE, Pope D, Dangerfield P, Platt MJ, Hall AJ. -Perthes disease in the UK: geographic and temporal Legg-Calve trends in incidence reflecting differences in degree of deprivation in childhood. Arthritis Rheum 2012; 64: 1673e9. Perry DC, Machin DMG, Pope D, et al. Racial and geographic -Perthes’ disease: a sysfactors in the incidence of Legg-Calve tematic review. Am J Epidemiol 2012; 175: 159e66. Perry DC, Bruce CE, Pope D, Dangerfield P, Platt MJ, Hall AJ. Perthes’ disease: deprivation and decline. Arch Dis Child 2011; 96: 1124e8. Hailer YD, Montgomery SM, Ekbom A, Nilsson OS, Bahmanyar S. Legg-Calve-Perthes disease and risks for
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cardiovascular diseases and blood diseases. Pediatrics 2010; 125: e1308e15. Herring JA, Kim HT, Browne R. Legg-Calve-Perthes disease. Part II: prospective multicenter study of the effect of treatment on outcome. J Bone Joint Surg Am 2004; 86: 2121e34. Bhatia NN, Pirpiris M, Otsuka NY. Body mass index in patients with slipped capital femoral epiphysis. J Pediatr Orthop 2006; 26: 197e9. Loder RT, Wittenberg B, DeSilva G. Slipped capital femoral epiphysis associated with endocrine disorders. J Pediatr Orthop 1995; 15: 349e56. Loder RT, Richards BS, Shapiro PS, Reznick LR, Aronson DD. Acute slipped capital femoral epiphysis: the importance of physeal stability. J Bone Joint Surg Am 1993; 75: 1134e40. Lowndes S, Khanna A, Emery D, Sim J, Maffulli N. Management of unstable slipped upper femoral epiphysis: a meta-analysis. Br Med Bull 2009; 90: 133e46.
Ó 2016 Published by Elsevier Ltd.
Please cite this article in press as: Dorman S, Perry D, Hip disorders in childhood, Surgery (2016), http://dx.doi.org/10.1016/j.mpsur.2016.10.009
(within 72 hours), and again at 6e8 weeks of age.1 A dislocated hip typically is identified by asymmetric skin creases and a short lower limb with limited abduction. Whilst asymmetric skin creases are a useful sign of DDH they are not specific, as these may be seen in around 25% of normal neonates, and therefore in isolation are of limited use. Hip stability may be tested using two specific movements of the hips termed the Barlow and the Ortolani manoeuvres (Figure 2). The efficacy of clinical screening is debated, as it lacks sensitivity (high false-negative rate), which is problematic as diagnostic delays necessitate greater degrees of operative and nonoperative interventions. Ultrasound is a more sensitive means of hip screening but, in contrast to clinical screening, has a higher false-positive rate resulting in potential for overtreatment. Ultrasound screening can be used to screen an entire population of newborns, or focus on selected groups who are abnormal on clinical screening, or are at particularly high risk of DDH. UK centres have generally adopted the ‘selective screening’ model. The NHS screening programme advocates ultrasound at 2 weeks of age if positive newborn physical examination and by 6 weeks of age if newborn examination negative but risk factors (first-degree relative or breech 36 weeks).2 Ultrasound screening remains controversial on cost/benefit grounds and a meta-analysis of randomized controlled trials has failed to demonstrate a significant reduction in late presenting DDH. Some countries (e.g. Germany and Switzerland) continue to use a population screening approach and therefore the debate of who and how to screen continues. Some children are inevitably not identified by current screening methods and their presentation is delayed. In children over 6 months old the diagnosis may be made with a plain anteroposterior (AP) pelvic radiograph. Children of walking age usually present with an abnormal gait e the result of having a shortened limb and altered joint mechanics, leading to a positive Trendelenburg sign. Figure 3 is a radiograph demonstrating a dislocated hip on the left side in a 14-month-old girl. An arrow indicates the position of the underdeveloped ossific nucleus of the femoral head. Two lines are helpful in assessing plain radiographs. Hilgenreiner’s horizontal line (H) is drawn through the triradiate cartilage at the floor of the acetabulum on each side. Perkins perpendicular (P) line is drawn at the edge of the bony acetabular roof and perpendicular to Hilgenreiner’s line. Together the lines create a ‘cross-wire’. A normal ossific nucleus is located in the lower inner quadrant of these ‘cross-wires’. The treatment of DDH is largely dependent upon the age at which the disease is identified. A neonate in whom DDH is identified is generally successfully treated in a removable split (e.g. Pavlik harness) which is required for around 3 months. Presentation at 6 months would necessitate reduction under anaesthesia, along with 6 months in plaster trousers (spica cast). As identification is increasingly delayed treatment becomes more invasive and the short and long-term morbidity greater. Early identification and treatment of DDH is therefore important to facilitate successful treatment, and minimize patient morbidity (Figure 4).
Hip disorders in childhood Sara Dorman Daniel Perry
Abstract Childhood disorders of the hip are encountered frequently in paediatric orthopaedic practice. They present initially to paediatricians, general practitioners and accident departments, and it is therefore important for both surgeons and generalists to have a good working knowledge of the common presentations. The challenge is to distinguish between disease processes that are benign and self-limiting (e.g. transient synovitis), acute and joint threatening (e.g. septic arthritis) or chronic and disabling (e.g. Perthes’ disease). This review primarily considers the epidemiology and aetiology of childhood hip diseases and provides a diagnostic framework, based upon age and risk factors. The important investigations and treatment options for each of the key differential diagnoses are also considered.
Keywords Developmental dysplasia of the hip; irritable hip; Perthes; septic arthritis; slipped capital femoral epiphysis; transient synovitis
Introduction The hip is a common focus of pathology in children’s orthopaedic surgery. The frequency of various conditions changes at different stages in a child’s development and therefore age is the key consideration when constructing a differential diagnosis for hip pathology in children (Figure 1).
Developmental dysplasia of the hip (DDH) DDH represents a spectrum of disease ranging from a hip which is poorly centred within the acetabulum, to a hip which is completely dislocated. ‘DDH’ has replaced the old term ‘congenital dislocation of the hip’ to recognize the wide spectrum of disease encountered, beyond simply ‘dislocated hips’. DDH affects predominantly girls (80%), and is usually detected in the neonatal period. The incidence of true DDH in the UK population is approximately 1 per 1000 live births. In unilateral disease the left hip is affected three times more commonly than the right. The aetiology of DDH is both genetic and environmental. The intrauterine environment is especially relevant, as ‘packaging’ disorders due to the limited space in-utero is thought to be an important aetiological factor (Box 1). Routine clinical examination of newborn infant hips is mandatory in the UK, and must be carried out at or soon after birth
Sara Dorman MB ChB BMSc (Hons) MRCSEd is a Speciality Registrar at Alder Hey Children’s Hospital, Liverpool, UK. Conflicts of interest: none declared. Daniel Perry MB ChB (Hons) PhD FRCS (Tr&Orth) is an Honorary Consultant Orthopaedic Surgeon and Senior Lecturer at Alder Hey Children’s Hospital and University of Liverpool, UK; NIHR Clinician Scientist. Conflicts of interest: none declared.
SURGERY --:-
Septic arthritis Septic arthritis is an infection of the synovium and joint space (Figure 5). The hip is the most commonly affected joint.
1
Ó 2016 Published by Elsevier Ltd.
Please cite this article in press as: Dorman S, Perry D, Hip disorders in childhood, Surgery (2016), http://dx.doi.org/10.1016/j.mpsur.2016.10.009
ORTHOPAEDICS V: PAEDIATRICS
Timeline for hip disease in children Birth
5 years old
Developmental hip dysplasia
10 years old
Transient synovitis
15 years old
Slipped capital femoral epiphysis
Perthes’ disease Septic arthritis
Perthes’ disease Septic arthritis Septic arthritis
Figure 1
this then results in dispersion of the infection into the joint space, resulting in septic arthritis (Figure 5c). Staphylococcus aureus is the most common infecting organism in septic arthritis,3 but the clinical context must be considered when predicting likely organisms; for example group B streptococcus is common in neonates and Kingella Kingae in younger children. Typically children are unwell, febrile and with a reluctance to move or put weight through the hip. Children may be immunocompromised or otherwise unwell due to systemic sepsis and often referred from intensive care environments. Ultrasound is useful to confirm a joint effusion, and joint aspiration is the gold standard means of diagnosis, based upon the presence of pus and organisms. In cases of culture-negative septic arthritis supplemental polymerase chain reaction techniques have been reported to improve detection of bacteria within joint fluid, particularly in Kingella Kingae infection. Urgent treatment includes surgical washout and intravenous antibiotics, without which joint destruction and growth arrest may occur.
Risk factors for developmental dysplasia of the hip C
C C C C C C
Positive family history (1 first-degree relative, or 2 second degree relatives) Breech presentation 36 weeks Large for gestational age (birthweight >5 kg) Neonatal foot deformity Oligohydramnios Prematurity Fetal moulding (e.g. torticollis)
Box 1
Infection usually begins as a focus of metaphyseal osteomyelitis. Infection reaches the bone by a blood-borne bacteraemia (Figure 5a). The vascularity of the metaphysis, and the anatomy of its thin-walled blood vessel loops, is thought to facilitate bacterial spread and make the metaphysis particularly vulnerable to infection. The metaphyseal cortex is thin and easily breached to allow infection to enter the subperiosteal space to form an abscess (Figure 5b). The hip, along with several other joints (e.g. shoulder, ankle and elbow), have a metaphysis which lies intraarticular. If a subperiosteal abscess ruptures within these joints
Transient synovitis Transient synovitis is a benign joint effusion. It usually occurs in boys between 4 and 8 years old. The typical presentation is a well
Dislocate Legs held flexed and adducted Femurs axially loaded Examiner’s index finger to feel over the child’s buttocks to detect the femoral head dislocating
Ortolani manoeuvre
Barlow manoeuvre
Clinical hip screening Reduce Hips are gently abducted Examiner feels for a ‘clunk’ to indicate that a dislocated hip has relocated within the acetabulum
Figure 2
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Figure 3 A dislocated hip on the left side in a 14-month-old girl.
2
Ó 2016 Published by Elsevier Ltd.
Please cite this article in press as: Dorman S, Perry D, Hip disorders in childhood, Surgery (2016), http://dx.doi.org/10.1016/j.mpsur.2016.10.009
ORTHOPAEDICS V: PAEDIATRICS
Treatment ladder for developmental dysplasia of the hip 2.5 years and above
18 months – 2.5 years
12–18 months 3–12 months
Birth – 3 months
Open reduction and pelvic and femoral osteotomy Open reduction and pelvic osteotomy
Open reduction and plaster (6 months)
Closed reduction in theatre and plaster (6 months)
Removable splint in clinic (3 months)
Figure 4 Age at diagnosis determines the entry point on the ladder, and failure of treatment moves an individual to the next step in the ladder. Duration of a typical treatment is shown in brackets. This therefore illustrates the importance of an early diagnosis in minimizing the nature and duration of the intervention required.
child with an unexplained limp, and it is the most common cause of an atraumatic limp in infancy. The cause of transient synovitis is unknown. There is a suggestion that transient synovitis may arise secondary to a viral illness although there is little evidence to support this. Certainly no viral pathogen has been identified with any consistency. The diagnosis is based upon a proven hip effusion with the exclusion of other potential causes. The treatment of transient synovitis is rest and analgesia. Symptoms tend to subside within 2 weeks, and usually within a few days. Ongoing symptoms should prompt the clinician to reconsider their diagnosis and initiate further investigation.
resolves spontaneously. Hip aspiration under general anaesthesia is the ‘gold standard’ means of excluding septic arthritis but is not routinely performed as this would yield a large number of negative results, as transient synovitis is very much more common than septic arthritis. Algorithms exist to help to differentiate between septic arthritis and transient synovitis. The most widely known algorithm was created based upon those children with a proven hip effusion, and uses four commonly recorded parameters to assist in making a diagnosis (Table 1).4 More recent modifications of this algorithm suggest that the inclusion of C-reactive protein (CRP) simplifies the protocol even further, as only CRP (>20 mg/ litre) and not weight bearing are independent predictors of septic arthritis.5 Whilst debate continues as to the validity of these algorithms the general consensus remains that they remain the most useful tools to date.6
Septic arthritis or transient synovitis? The most significant difficulty, when faced with a child with presumed transient synovitis, is excluding septic arthritis. Septic arthritis requires urgent treatment, though transient synovitis
Development of septic arthritis
Vessels
Breached periosteum
Sub-periosteal collection
Abscess Growth plate a
Joint capsule b
c Figure 5
SURGERY --:-
3
Ó 2016 Published by Elsevier Ltd.
Please cite this article in press as: Dorman S, Perry D, Hip disorders in childhood, Surgery (2016), http://dx.doi.org/10.1016/j.mpsur.2016.10.009
ORTHOPAEDICS V: PAEDIATRICS
Algorithm for differentiating between transient synovitis and septic arthritis Factors for predicting septic arthritis C Fever >38.5 C C Non-weight bearing C Erythrocyte sedimentation rate >40 mm/hour C Serum white cell count >12 10 9 Number of factors present Probability of septic arthritis (%) 0 <0.2 1 3.0 2 40 3 93.1 4 99.6
a
Table 1
Perthes’ disease Perthes’ disease is an idiopathic avascular necrosis of a developing femoral head. It usually affects boys between 4 and 8 years old. The lifetime incidence of Perthes’ disease within the UK is approximately 1 per 1200 children.7 The typical presentation is with hip or knee pain and a limp. Children are thought to have a hyperactive tendency and be generally shorter than their peers. White children are mainly affected, Asian children rarely and black children almost never.8 The incidence also varies with social class, with the most deprived children having the highest incidence.9 The cause of Perthes’ disease is unknown. It is known that around this age a single vessel supplies the epiphysis called the ‘lateral ascending epiphyseal artery’, a branch of the ‘medial circumflex artery’. In Perthes’ disease this vessel is thought to become occluded, resulting in the necrosis of the epiphysis. The origin of the occlusion remains unknown as no extraluminal or intraluminal cause may be identified with any consistency. Recently, investigators have identified associations with parental smoking, and an elevated risk of ischaemic heart disease in middle-aged adults who suffered with Perthes’ disease as
b Figure 7 Anteroposterior and lateral radiograph demonstrating a leftsided slipped capital femoral epiphysis. Klein’s line is drawn on the plain AP radiograph along the upper border of the femoral neck. The line usually intersects the epiphysis. In an abnormal situation the line fails to intersect the epiphysis. The arrow indicates a subtle irregularity within the metaphysis called the ‘blanch sign’. The lateral projection demonstrates the slip more clearly. There is less than 1/3 displacement and therefore the slip is ‘mild’.
infants,10 and thus a common underlying pathology may be responsible. The diagnosis of Perthes’ disease is made by a plain AP radiograph of the pelvis (Figure 6). Classical radiographic features of Perthes’ disease include sclerosis, fragmentation and eventual flattening of the proximal femoral epiphysis. Treatment requires ‘containment’ of the hip within the acetabulum. This works on the assumption that the femoral epiphysis is ‘softened’ by Perthes’ disease. Containment therefore seeks to maintain the epiphysis deep within the hemispherical ‘mould’ of the acetabulum. This maintains the femoral head sphericity until it once again becomes firm e generally occurring after around 3 years. This effect can be achieved by conservative or surgical means. Conservative treatment often makes use of a brace or spica plaster to maintain the legs in abduction, while surgery repositions the femoral head or augments the acetabulum to achieve the goals of ‘containment’. Prognosis depends upon age, sex and extent of epiphyseal involvement.11
Slipped capital femoral epiphysis (SCFE) SCFE is also known as slipped upper femoral epiphysis (SUFE). An SCFE is characterized by an anterior slip of the metaphysis
Figure 6 A radiograph illustrating Perthes’ disease. The right femoral head can be seen to be flattened and more dense (sclerosis).
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Please cite this article in press as: Dorman S, Perry D, Hip disorders in childhood, Surgery (2016), http://dx.doi.org/10.1016/j.mpsur.2016.10.009
ORTHOPAEDICS V: PAEDIATRICS
Overall summary Diagnosis
Lifetime incidence
Typical age of presentation (years)
Male:female ratio
Risk factors
Developmental dysplasia of the hip
1:1000 True dislocation
Neonates
1:4
Septic arthritis
1:1000
Under 3
1.5e2:1
Transient synovitis Perthes’ disease
1:400 1:1000
4e10 4e8
3:1 4:1
Slipped capital femoral epiphysis
1:1000
>10
1.5:1
Breech presentation Family history Oligohydramnios Foot deformity Concurrent disease Immunosuppression Recent viral illness Small for age Socioeconomic deprivation Obesity Endocrinopathies
Table 2
Treatment is by prompt recognition and urgent screw fixation of the slip to prevent further deterioration. In certain situations the slip may have progressed beyond the acceptable limits for fixation, and in such instances an osteotomy can be performed to realign the bones to correct the deformity and facilitate fixation. The prognosis is dependent on the development of avascular necrosis and the severity of the slip (Table 2).
relative to the epiphysis, endangering the blood supply to the epiphysis. It typically occurs above 10 years old, and affects boys 1.5 times more commonly than girls. The physis becomes particularly vulnerable to injury around puberty, which is believed to be associated with rapid growth. Several groups are at particularly high risk of SCFE. Obesity exerts high forces on the physis and this may precipitate a slip.12 Endocrine abnormalities, such as hypothyroidism and treatment with growth hormone, have a tendency to weaken the physis thereby increasing the frequency of SCFE.13 SCFEs may present with acute and sudden pain such that the patient cannot bear weight (unstable slips), or as chronic pain whereby they are still able to bear weight (stable slips).14 Pain may often be referred to the knee such that a patient presents with isolated knee pain. The most sensitive clinical sign of SCFE is pain or discomfort on internal rotation of the hip. A plain AP radiograph of the pelvis may be unremarkable if the slip is subtle. A lateral projection is more sensitive to identify such slips and is therefore essential. Klein’s line may be drawn on the radiograph to help identify the SCFE (Figure 7). SCFE is categorized radiologically into mild, moderate and severe depending on the degree of displacement of the epiphysis on the metaphysis: 0e1/3 mild 1/3e1/2 moderate > 1/2 severe. About 80% of slips are ‘stable’ at presentation, and such cases have a minimal risk of avascular necrosis. There are many reports of stable SCFEs going undetected for many months as the individual complained of ‘knee pain’ and the clinician failed to consider that this pain may be referred from the hips. Diagnostic delays worsen the outcome of stable SCFE as the femoral head progressively deforms,15 or occasionally the slip may suddenly worsen precipitating an unstable slip. Early detection through disease awareness, and considering the hip when presented with knee pain, is important to minimize patient morbidity. Unstable slips carry a poor prognosis because the slip often tears the blood supply leading to avascular necrosis in 50% of cases.
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Other considerations Most childhood hip problems are due to one of the pathologies discussed above in this review. However, other diagnoses should be considered in patients in whom symptoms, signs and investigation results do not conform to the ‘typical’ patterns. Trauma is always a consideration in any orthopaedic presentation and of particular importance in children is the possibility of nonaccidental injury. Other diseases include the inflammatory arthritides, local benign or malignant tumours and systemic disease such as childhood leukaemia. A REFERENCES 1 Standing Medical Advisory Committee and Standing Nursing and Midwifery Advisory Committee Working Party. Screening for the detection of congenital dislocation of the hip. Arch Dis Child 1986; 61: 921e6. 2 Public Health England. Newborn and Infant Physical Examination Screening Programme Handbook 2016/2017. Retrieved 31 May, 2016 from https://www.gov.uk/government/uploads/system/ uploads/attachment_data/file/524425/NIPE_Programme_ Handbook_2016_to_2017_.pdf. 3 Goergens ED, McEvoy A, Watson M, Barrett IR. Acute osteomyelitis and septic arthritis in children. J Paediatr Child Health 2005; 41: 59e62. 4 Kocher MS, Zurakowski D, Kasser JR. Differentiating between septic arthritis and transient synovitis of the hip in children: an evidence-based clinical prediction algorithm. J Bone Joint Surg Am 1999; 81: 1662e70. 5 Singhal R, Perry DC, Khan FN, et al. The use of CRP within a clinical prediction algorithm for the differentiation of septic arthritis
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Please cite this article in press as: Dorman S, Perry D, Hip disorders in childhood, Surgery (2016), http://dx.doi.org/10.1016/j.mpsur.2016.10.009
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Ó 2016 Published by Elsevier Ltd.
Please cite this article in press as: Dorman S, Perry D, Hip disorders in childhood, Surgery (2016), http://dx.doi.org/10.1016/j.mpsur.2016.10.009