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Irritable hip
(i) Irritable Hip
J. A. Fernandez de Valderrama cysts, osteoid osteomas and other tumours can also be easily detected with plain radiographs. Lack of symptoms of generalised illness make septic arthritis and osteomyelitis highly improbable, and both may easily be ruled out if the temperature, white blood cell count and erythrocyte sedimentation rate are normal. Tuberculous synovitis has a chronicity which acute synovitis does not have. Hip inflammation by rheumatic fever and juvenile rheumatoid disease may be diagnosed by specific tests as well as their clinical course. Plain radiographs are not reliable for the diagnosis and evaluation of hip joint effusions. Muscle shadows can vary with different positions of the femur, especially abduction. Increase of the medial joint space distance should not be taken as an indication of a hip joint effusion which have always been confirmed by joint aspiration under general anaesthesia, but today they may easily be diagnosed by ultrasonography. In the presence of unilateral hip joint disease, an expert sonographist can detect minor fluid collections of only one or two millilitres, but there is no way to differentiate sterile from purulent or hemorragic effusions which can only be confirmed by joint aspiration. Both CT and MRI are capable of detecting the early epiphyseal changes of Perthes’ disease, and small infiltrations of the bone marrow, like leukaemia, months before they can be detectable in plain radiographs. Nevertheless, quantitative bone scanning of the capital epiphysis with 99m Tc-MDP continues to be the most valuable method for the diagnosis of epiphyseal ischaemia.
Introduction In the growing child a limp, with or without pain, referred to the knee, thigh or groin, is often the first manifestation of hip disease. The term Irritable Hip refers to a syndrome of possible varied aetiology, in which the most common factor is the fleeting nature of the symptoms. Transient synovitis. ‘observation hip’, coxitis fugax, transitory coxitis, acute transient epiphysitis and toxic synovitis, are all synonymous with this common disease of childhood, recognised as a clinical entity since it was first reported by Lovat and Morse in 1892. l The other diagnostic features are the failure to prove a specific etiology and the absence of demonstrable bone or cartilage lesions. Therefore the clinical diagnosis may only be confirmed by excluding more severe processes such as osteomyelitis, septic arthritis, juvenile rheumatoid arthritis, slipped upper femoral epiphysis, Perthes’ disease, fracture and tumours.
Differential Diagnosis All children with symptoms of hip disease should have a careful clinical examination. Limitation, with or without pain of active or passive joint movements should be taken seriously and considered a positive manifestation of hip disease. Routine radiographs, standard AP and frog leg position,‘must be taken. ‘Osteochondritis’ of the femoral head and slipped upper femoral epiphysis have a selective age of appearance and should be easily diagnosed with AP and axial views of the hips and pelvis. Fractures, bone
Clinical Entity
J. A. Femandez de Valderrama MD, Chief of Orthopaedic Service, Hospital Central Cruz Roja, Associate Professor Universidad Computense, Madrid, Spain. Currpnt Orrhopaedrrr (I 991) 5. 151 124 Q 1991 Lon,gnan
Group kK
Ltd
Failure to prove any specific form of hip disease 151
1%
CURRENT
ORTHOPAEDICS-MINI-SYMPOSIUM:
THE HIP IN CHILDHOOD
confirms the diagnosis of irritable hip. Symptoms and signs are well described in the literature.2T3,4 The most common being: onset of hip pain with limitation of active and passive movements, increase or moderate increase of erythrocyte sedimentation rate and absence of bony or cartilaginous lesions on plain radiographs taken in AP, neutral and frog position. Boys are more frequently affected than girls. Right and left hips appear to be equally affected. A few patients may have symptoms from both hips simultaneously or at different periods. The mean age of appearance is around 6 or 7 years. No seasonal variation in the onset of symptoms has been demonstrated. Few of the children may have intermittent pain with or without limping for weeks or months, but in most cases the symptoms settle within 2 or 3 weeks. Recurrence of transient synovitis is not infrequent and has been specifically studied by Illingworth5 who found no difference in the aetiology or clinical course between cases with a single attack and those with a recurrence. Landin et aL6 in another prospective study of a closed population found an annual incidence of 0.2x, and the accumulated risk of suffering at least one episode was 3%. The risk of recurrence was 20 times greater than the risk of having a single episode. The incidence of transient synovitis is equivalent to that of fracture of the clavicle, the fourth most common skeletal injury from birth to 16 years. Aetiology Sometimes an upper respiratory, gastrointestinal or urinary tract infection or minor trauma has preceded the symptoms, and slight pyrexia may be occasionally present. The predominant role of upper respiratory infection claimed by some authors7,* was not significant in our experience.3 Hardinge,9 in a careful prospective study of children with transient synovitis, did not find any connection with infection by staphylococci or streptococci, with allergy or with viral infection; he did find a loose similarity between the monthly incidence of tibia1 fractures and transient synovitis but could not exclude or confirm the relation with trauma. Sainsbury et allo in an extensive seasonal study of irritable hips, fractures and head injuries, discounts trauma as a possible aetiology of irritable hips. Diagnostic Methods Most of the irritable hips will present some degree of synovitis and joint effusion which should be confirmed by sonography. Plain radiographs may show small degrees of widening of the medial joint space of one or two millimetres in unilateral disease at admission, but this sign is more frequent with persistent symptoms and recurrences, and may persist after 1 year of follow-up examination with minor degrees of coxa magna. Widening of the cranial joint space is more difficult to
evaluate. Slight osteoporosis of the epiphysis and metaphysis may be seen in older children with persistent symptoms. Intracapsular pressure measurements in those patients with effusions confirmed by sonography show an increase as compared to normal. l l, l2 Pressures are usually given in KPa (1 KPa = 7,5 mm HG) and are very clearly influenced by the position of the hip. Maximal figures of around 23-26 KPa are recorded with the hip in extension and inward rotation, decreasing to a minimum of 2-3 KPa with the hip in 45% of flexion. Joint aspiration reduces pressure progressively to zero in the neutral position, and the amount of aspirated fluid is usually between 2 and 6 ml. Measurements should be performed under general anaesthesia. Most of the children experience marked relief of pain and increased joint mobility following hip joint aspiration. Serial sonography’ l shows recurrence of the effusion the day after the joint aspiration. Frequently, intracapsular pressure will decrease progressively in the following days while the symptoms subside. The aspirated joint fluid is usually clear. Cultures, cytologic and chemical analysis do not show any specific abnormalities. Wingstrand” has studied the concentration of proteoglycans in joint fluid specimens with an Enzyme Linked Immunoabsorbent Assay (ELISA). This concentration was considerably elevated. He gives figures of 238 g/ml for transient synovitis and 65 g/ml in Perthes’ disease, but found no correlation between the level of proteoglycan antigen concentration and the volume of aspirated fluid, nor with the level of intracapsular pressure. This finding proves that there is an imbalance in articular cartilage metabolism as proteoglycans are molecules that are degraded and released from the articular cartilage into the synovial fluid early in an arthritic process. Bone scintigraphy with 99m Tc-MDP in the irritable hip syndrome is indicated because of its high diagnostic sensitivity and specificity in the diagnosis of Perthes’ disease months before any changes are detectable in plain radiographs. This has led to an extensive experience of the scintigraphic appearance in transient synovitis. Almost constantly, normal or diffusely increased isotope uptake is seen in the affected hip. But some authors”,i3 have reported findings of decreased uptake of the capital epiphysis that has returned to normal spontaneously or after aspiration within 1-15 days. This has been interpreted as possible episodes of transient ischaemia, but according to Kallio i* these changes may be a consequence of the increase in the intracapsular pressure produced by the position of hip extension during the examination. Computed tomography (CT) needs no skill on the part of the examiner and gives an excellent evaluation of hip joint effusions and epiphyseal anomalies, but given the accuracy of sonography, in expert hands, it should be reserved for those infrequent patients where
_~ ___._--bilateral hip joint effusions are suspected. Accurate measurements of the ultrasonographic hip joint space, without an opposite normal joint for comparison, could be a challenge even for the expert sonographist. Magnetic Resonance Imaging (MRI), has become an excellent technique for evaluation of the epiphyseal lesion and soft tissue changes of Perthes’ disease, giving excellent images, in the coronal and axial planes of the articular cartilage, and the degree of joint congruity and head containment. So far, we do not know of any detailed study with MRI of the articular cartilage ‘swelling’ and the slight coxa magna found in some of the patients with transient synovitis.
Treatment There is no specific treatment except rest for the irritable hip. Children with a painful hip with limited range of movement should be kept at rest until the symptoms disappear. The ideal position should be in 45” of flexion and some external rotation, to reduce to a minimum the intracapsular hip joint pressure. The value of continuous traction is argued because of its possible danger in producing epiphyseal ischaemia if applied in extension. Nevertheless, continuous skin traction with one or two kilograms of weight applied in line with the flexion contracture helps to relieve pain and to force rest in bed for the required time. Hip extension should be avoided as it has been shown to increase considerably the intracapsular joint pressure. The symptoms tend to subside when weightbearing is eliminated. The therapeutic value of hip joint aspiration is doubtful as the effusion recurs within 24 h, but if the hip is very painful and sonography shows a large effusion, a joint aspiration may be justified, specially if it can be done without general anaesthesia. Ultrasound guided aspiration with local anaesthesia and heavy sedation has been reported to alleviate pain and reduce hospital stay.’ 4 The use of intraarticular injection of glucocorticoids has been suggested in order to decrease pathological cartilage metabolism and cartilage degradation in arthritis and synovitis. l 3-l 5 Precautions against the possibility of a bacterial synovitis are mandatory. There is no reported experience of its possible beneficial effect in transient synovitis. Aspirin and other non-steroidal anti-inflammatory drugs, are usually given in order to alleviate pain and ‘inflammation’, but their true therapeutic value has not been statistically proven.
Sequelae Irritable hip continues to be the most common and frequent cause of hip pain in childhood, and in the great majority of cases the synovitis heals without long-term ill effects. It has been considered that if the hip synovitis did not produce ischaemia of the capital epiphysis, and consequent Perthes’ disease, the tran-
IRRITABLE
HIP
_.__-_
153
sient hip syndrome will not produce future articular pathology. However in 1963 we presented evidence suggesting that in a few patients irreversible changes of the hip joint could occur, leading to degenerative arthritis.3 Among 23 patients examined for an average period of 2 1 years after the transient hip syndrome, we found that 12 of them presented abnormal radiographic changes in the ‘observed’ hip joint, though they were severe in only two patients. It was significant that the more severe sequelae occurred in the older age group (all above 8 years of age). With few exceptions, they also had a more severe clinical picture. That an increase in blood supply to epiphyseal cartilage will stimulate growth is well known. Therefore it is possible that the inflammatory hypervascularity may produce not only a variable degree of osteoporosis, but also a growth stimulus which, if persistent enough, would result in an enlargement of the corresponding epiphysis (coxa magna). Experimental synovitis of the hip joint in growing rabbits] 6 causes enlargements of the cartilaginous parts of the acetabulum, femoral head and neck that could lead to incongruity and subluxation. Widening of the medial joint space, recognised as an early sign of Perthes’ disease has been found to accompany coxa magna in 88% of patients,” and transient synovitis in up to 58”/;;.‘” Increase of the medial joint space of 1 mm or more at admission is considered the most important risk factor for later development of coxa magna. ’ 9 ‘The late occurrence of osteoarthritis in patients with some persistent degree of coxa magna at the end of growth is a logical consequence of the joint incongruity. but it is more difficult to explain in patients with hips of apparently normal configuration. Chondral damage has been demonstrated in experimental synovitis; the increased levels of proteoglycan fragments found in the joint fluid of some children with transient synovitis are comparable to levels found in adults with reactive arthritis.ls It is possible to speculate that some hips with transient synovitis in the older age group would retain some type of cartilage damage that could lead to a type of osteoarthritis, similar to that developing in joints previously affected by acute or chronic inflammation.“’
Relationship to Perthes’ Disease The possible relation between Perthes’ disease and irritable hip has often been considered. Both entities affect children of the same age group with a similar sex distribution. Several authors have reported cases of Perthes’ disease developing several months after an episode of irritable hip, with apparent normality of the hips on plain radiographs. The reported risk” varies between 0 and 17x, and this has encouraged the search for a common patho-
154
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ORTHOPAEDICS-MINI-SYMPOSIUM:
THE
genesis, despite the fact that only in 15% of the patients the radiologic diagnosis of Perthes’ disease cannot be made on the first consultation.23 It seems logical to think that if transient synovitis produces a joint effusion with significant pressure, this should be able to produce epiphyseal ischaemia in a joint with a unique vascular anatomy.24 This has been proved to occur experimentally in growing animals.25 Reduced radioisotope uptake has been reported in children with various hip joint disorders such as transient synovitis, septic arthritis and traumatic intracapsular bleeding, but the development of Perthes’ disease has not been reported after infective arthritis or joint haemorrhage. The haemophilic hip joint arthropathy could present temporary Perthes’ like changes, but always evolves to joint destruction and ankylosis. The proportion of patients who develop Perthes’ disease after a clinical episode of irritable hip is very small. Most of the patients with irritable hip will make a permanent recovery without any treatment, and the others will develop a minor degree of coxa magna without proof of any bone necrosis. Recent prospective studies show a nil or minimal incidence of Perthes’ disease developing after transient synovitis and joint effusion proven by sonography and/orjoint aspiration. It seems significant that studies of joint effusion in patients with transient synovitis and Perthes’ disease almost consistently show different characteristics. Intra-capsular pressure is consistently lower in patients with Perthes’ disease and the changes in pressure are less influenced by the position of the hip. The amount of aspirated synovial fluid is rather small, and the concentration of proteoglycan fragments is also considerably lower than in transient synovitis. l l These findings support the opinion that the synovitis present in Perthes’ disease is secondary to the osteochondral lesion. Bone scanning with 99m Tc-MDP and pin-hole collimatortechniqueisthemostreliablewayofdetecting the epiphyseal avascular changes characteristic of the earlier stage of Perthes’disease. Transient synovitis may show initially a decrease in isotope uptake in the proximal femoral epiphysis and even in the growth plate, indicating a disturbance in blood supply during the first week of symptoms. l l This decrease of uptake has been shown to be influenced by the position of extension of the hip and disappears by flexing the hip and also by joint aspiration.*l When symptoms have lasted more than 20-30 days, a reactive hyperaemia with increased isotope uptake is very frequent. Children with Perthes’ disease have a significant retardation of skeletal age and growth,24 while the distribution of skeletal age is normal in patients with transient synovitis.*’ Occurrence of symptomatic transient synovitis on one side and symptoms-free Perthes’ disease on the other have been reported in two patients;** in both cases the hips with synovitis made a permanent recovery.
HIP
IN CHILDHOOD
Bilateral hip disease is also much more frequent in Perthes’ than in transient synovitis. Considering all these facts, it seems logical to think that Perthes’ disease and transient synovitis may be two different diseases, each with its own incidence, occurring in the same age group. Perthes’ disease tends to be considered a focal expression of a general minor disorder of skeletal growth, and the etiology of transient synovitis is unknown, but possibly varied. According to Kallio, *l the rare accidental coincidence of transient synovitis and Perthes’ disease in the same patient appears to be statistically possible.
References 1. Lovett R W, Morse J L. A transient or ephemeral form of hip disease, with a report of cases, Boston Med Surg J 1892; 127: 61-63 2. Ferguson A B. Synovitis of the hip and leg-Perthes’ Disease. Clinical Orthop 1954; 4: 18&188 J A Femandez De. The ‘Observation Hip’ 3. Valderrama syndrome and its late sequelae. J Bone Joint Surg 1963; 45B: 462470 4. Sharwood P P. The irritable hip syndrome. A long-term follow-up. Acta Orthop Stand 1981; 52: 633-638 5. Illingworth C M. Recurrence of transient synovitis of the hip. Arch Dis Child 1983; 58 : 620-623 6. Landin LA, Danielson L G, Wattsgard C. Transient synovitis of the hip. Its incidence, epidemiology and relation to Perthes’ disease. J Bone Joint Surg 1987; 69B: 238-242 I. Miller 0 L. Acute transient epiphysitis of the hip joint. JAMA 1931; 96: 575-519 8. Speck A. Transient synovitis of the hip joint in children. Pediatrics 1959; 24: 1042-1049 9. Hardinge K. The etiology of transient synovitis of the hip in childhood. J Bone Joint Surg 1970; 52B: lO(r107 10. Sainsbury C P Q, Newcombe R G, Essex-Cater A. Irritable hips: Relationship with trauma. Letter, Lancet 1986; January 25; 1 (8474): 220 H. Transient synovitis of the hip in the child. Acta 11. Wingstrand Orthop Stand 1986; Supplementum 219 ~0157 12. Kallio P, Ryiippy S. Hyperpressure in juvenile hip disease. ActaOrthop Stand 1985; $6: 211-214. 13. Sutherland A D. Savage J P. Paterson DC. Foster B K. The nuclide bone s&n in tie diagnosis and management of Perthes’ disease. J Bone Joint Surg 1980; 62B: 300-306 14. Hill SA, Maclamon J C. Ultrasound guided aspiration for transient synovitis of the hip. J Bone Joint Surg 1990; 72B: 852-853 effects on 15. Saxne T, Heineg%rd D, Wollheim F. Therapeutic cartilage metabolism in arthritis as measured by release of proteoglycan structures to the synovial fluid. Ann Rheum Dis 1986; 45: 491497 D H, Ayer A. Synovitis of the hip joint. An 16. Gershuni-Gordon experimental model in rabbits. J Bone Joint Surg 1974; 56B: 69-77 17. Harris L J, Graig W A. Acetabular dysplasia following transient synovitis of the hip. Orthop Rev 1979; 8: I55 18. Sharwood P F. The irritable hip syndrome. A long-term follow up. Acta Orthop Stand 1981; 52: 633-638 19. Kallio P E. Coxa magna following transient synovitis of the hip. Clin Orthop 1988; 228 : 49-56 of the 20. Harrison M H M. Schaiowicz F. Trueta J. Osteoarthritis hip: A study of the natire and evolution of the disease. J Bone Joint Surg 1953; 35B: 598-626 21. Kallio P, RyBppy S. Transient synovitis and Perthes’ disease. J Bone Joint Surg 1986; 68B: 808-811 22. Gonzalez Babe-J, Femandez de Valderrama J A. Perthes’ disease and irritable hip. 1966; Unpublished data of intracapsular 23. Kemp H B S. Perthes’ hisease. Theinfluence tamponade on the circulation in the hip joint of the dog. Clin Orthop 1981; 156: 105-114 24. Harrison M H M, Burwell R G. Perthes’ disease: A concept of pathogenesis. ClinOrthop 1981; 156: 115-127
J. A. Fernandez de Valderrama cysts, osteoid osteomas and other tumours can also be easily detected with plain radiographs. Lack of symptoms of generalised illness make septic arthritis and osteomyelitis highly improbable, and both may easily be ruled out if the temperature, white blood cell count and erythrocyte sedimentation rate are normal. Tuberculous synovitis has a chronicity which acute synovitis does not have. Hip inflammation by rheumatic fever and juvenile rheumatoid disease may be diagnosed by specific tests as well as their clinical course. Plain radiographs are not reliable for the diagnosis and evaluation of hip joint effusions. Muscle shadows can vary with different positions of the femur, especially abduction. Increase of the medial joint space distance should not be taken as an indication of a hip joint effusion which have always been confirmed by joint aspiration under general anaesthesia, but today they may easily be diagnosed by ultrasonography. In the presence of unilateral hip joint disease, an expert sonographist can detect minor fluid collections of only one or two millilitres, but there is no way to differentiate sterile from purulent or hemorragic effusions which can only be confirmed by joint aspiration. Both CT and MRI are capable of detecting the early epiphyseal changes of Perthes’ disease, and small infiltrations of the bone marrow, like leukaemia, months before they can be detectable in plain radiographs. Nevertheless, quantitative bone scanning of the capital epiphysis with 99m Tc-MDP continues to be the most valuable method for the diagnosis of epiphyseal ischaemia.
Introduction In the growing child a limp, with or without pain, referred to the knee, thigh or groin, is often the first manifestation of hip disease. The term Irritable Hip refers to a syndrome of possible varied aetiology, in which the most common factor is the fleeting nature of the symptoms. Transient synovitis. ‘observation hip’, coxitis fugax, transitory coxitis, acute transient epiphysitis and toxic synovitis, are all synonymous with this common disease of childhood, recognised as a clinical entity since it was first reported by Lovat and Morse in 1892. l The other diagnostic features are the failure to prove a specific etiology and the absence of demonstrable bone or cartilage lesions. Therefore the clinical diagnosis may only be confirmed by excluding more severe processes such as osteomyelitis, septic arthritis, juvenile rheumatoid arthritis, slipped upper femoral epiphysis, Perthes’ disease, fracture and tumours.
Differential Diagnosis All children with symptoms of hip disease should have a careful clinical examination. Limitation, with or without pain of active or passive joint movements should be taken seriously and considered a positive manifestation of hip disease. Routine radiographs, standard AP and frog leg position,‘must be taken. ‘Osteochondritis’ of the femoral head and slipped upper femoral epiphysis have a selective age of appearance and should be easily diagnosed with AP and axial views of the hips and pelvis. Fractures, bone
Clinical Entity
J. A. Femandez de Valderrama MD, Chief of Orthopaedic Service, Hospital Central Cruz Roja, Associate Professor Universidad Computense, Madrid, Spain. Currpnt Orrhopaedrrr (I 991) 5. 151 124 Q 1991 Lon,gnan
Group kK
Ltd
Failure to prove any specific form of hip disease 151
1%
CURRENT
ORTHOPAEDICS-MINI-SYMPOSIUM:
THE HIP IN CHILDHOOD
confirms the diagnosis of irritable hip. Symptoms and signs are well described in the literature.2T3,4 The most common being: onset of hip pain with limitation of active and passive movements, increase or moderate increase of erythrocyte sedimentation rate and absence of bony or cartilaginous lesions on plain radiographs taken in AP, neutral and frog position. Boys are more frequently affected than girls. Right and left hips appear to be equally affected. A few patients may have symptoms from both hips simultaneously or at different periods. The mean age of appearance is around 6 or 7 years. No seasonal variation in the onset of symptoms has been demonstrated. Few of the children may have intermittent pain with or without limping for weeks or months, but in most cases the symptoms settle within 2 or 3 weeks. Recurrence of transient synovitis is not infrequent and has been specifically studied by Illingworth5 who found no difference in the aetiology or clinical course between cases with a single attack and those with a recurrence. Landin et aL6 in another prospective study of a closed population found an annual incidence of 0.2x, and the accumulated risk of suffering at least one episode was 3%. The risk of recurrence was 20 times greater than the risk of having a single episode. The incidence of transient synovitis is equivalent to that of fracture of the clavicle, the fourth most common skeletal injury from birth to 16 years. Aetiology Sometimes an upper respiratory, gastrointestinal or urinary tract infection or minor trauma has preceded the symptoms, and slight pyrexia may be occasionally present. The predominant role of upper respiratory infection claimed by some authors7,* was not significant in our experience.3 Hardinge,9 in a careful prospective study of children with transient synovitis, did not find any connection with infection by staphylococci or streptococci, with allergy or with viral infection; he did find a loose similarity between the monthly incidence of tibia1 fractures and transient synovitis but could not exclude or confirm the relation with trauma. Sainsbury et allo in an extensive seasonal study of irritable hips, fractures and head injuries, discounts trauma as a possible aetiology of irritable hips. Diagnostic Methods Most of the irritable hips will present some degree of synovitis and joint effusion which should be confirmed by sonography. Plain radiographs may show small degrees of widening of the medial joint space of one or two millimetres in unilateral disease at admission, but this sign is more frequent with persistent symptoms and recurrences, and may persist after 1 year of follow-up examination with minor degrees of coxa magna. Widening of the cranial joint space is more difficult to
evaluate. Slight osteoporosis of the epiphysis and metaphysis may be seen in older children with persistent symptoms. Intracapsular pressure measurements in those patients with effusions confirmed by sonography show an increase as compared to normal. l l, l2 Pressures are usually given in KPa (1 KPa = 7,5 mm HG) and are very clearly influenced by the position of the hip. Maximal figures of around 23-26 KPa are recorded with the hip in extension and inward rotation, decreasing to a minimum of 2-3 KPa with the hip in 45% of flexion. Joint aspiration reduces pressure progressively to zero in the neutral position, and the amount of aspirated fluid is usually between 2 and 6 ml. Measurements should be performed under general anaesthesia. Most of the children experience marked relief of pain and increased joint mobility following hip joint aspiration. Serial sonography’ l shows recurrence of the effusion the day after the joint aspiration. Frequently, intracapsular pressure will decrease progressively in the following days while the symptoms subside. The aspirated joint fluid is usually clear. Cultures, cytologic and chemical analysis do not show any specific abnormalities. Wingstrand” has studied the concentration of proteoglycans in joint fluid specimens with an Enzyme Linked Immunoabsorbent Assay (ELISA). This concentration was considerably elevated. He gives figures of 238 g/ml for transient synovitis and 65 g/ml in Perthes’ disease, but found no correlation between the level of proteoglycan antigen concentration and the volume of aspirated fluid, nor with the level of intracapsular pressure. This finding proves that there is an imbalance in articular cartilage metabolism as proteoglycans are molecules that are degraded and released from the articular cartilage into the synovial fluid early in an arthritic process. Bone scintigraphy with 99m Tc-MDP in the irritable hip syndrome is indicated because of its high diagnostic sensitivity and specificity in the diagnosis of Perthes’ disease months before any changes are detectable in plain radiographs. This has led to an extensive experience of the scintigraphic appearance in transient synovitis. Almost constantly, normal or diffusely increased isotope uptake is seen in the affected hip. But some authors”,i3 have reported findings of decreased uptake of the capital epiphysis that has returned to normal spontaneously or after aspiration within 1-15 days. This has been interpreted as possible episodes of transient ischaemia, but according to Kallio i* these changes may be a consequence of the increase in the intracapsular pressure produced by the position of hip extension during the examination. Computed tomography (CT) needs no skill on the part of the examiner and gives an excellent evaluation of hip joint effusions and epiphyseal anomalies, but given the accuracy of sonography, in expert hands, it should be reserved for those infrequent patients where
_~ ___._--bilateral hip joint effusions are suspected. Accurate measurements of the ultrasonographic hip joint space, without an opposite normal joint for comparison, could be a challenge even for the expert sonographist. Magnetic Resonance Imaging (MRI), has become an excellent technique for evaluation of the epiphyseal lesion and soft tissue changes of Perthes’ disease, giving excellent images, in the coronal and axial planes of the articular cartilage, and the degree of joint congruity and head containment. So far, we do not know of any detailed study with MRI of the articular cartilage ‘swelling’ and the slight coxa magna found in some of the patients with transient synovitis.
Treatment There is no specific treatment except rest for the irritable hip. Children with a painful hip with limited range of movement should be kept at rest until the symptoms disappear. The ideal position should be in 45” of flexion and some external rotation, to reduce to a minimum the intracapsular hip joint pressure. The value of continuous traction is argued because of its possible danger in producing epiphyseal ischaemia if applied in extension. Nevertheless, continuous skin traction with one or two kilograms of weight applied in line with the flexion contracture helps to relieve pain and to force rest in bed for the required time. Hip extension should be avoided as it has been shown to increase considerably the intracapsular joint pressure. The symptoms tend to subside when weightbearing is eliminated. The therapeutic value of hip joint aspiration is doubtful as the effusion recurs within 24 h, but if the hip is very painful and sonography shows a large effusion, a joint aspiration may be justified, specially if it can be done without general anaesthesia. Ultrasound guided aspiration with local anaesthesia and heavy sedation has been reported to alleviate pain and reduce hospital stay.’ 4 The use of intraarticular injection of glucocorticoids has been suggested in order to decrease pathological cartilage metabolism and cartilage degradation in arthritis and synovitis. l 3-l 5 Precautions against the possibility of a bacterial synovitis are mandatory. There is no reported experience of its possible beneficial effect in transient synovitis. Aspirin and other non-steroidal anti-inflammatory drugs, are usually given in order to alleviate pain and ‘inflammation’, but their true therapeutic value has not been statistically proven.
Sequelae Irritable hip continues to be the most common and frequent cause of hip pain in childhood, and in the great majority of cases the synovitis heals without long-term ill effects. It has been considered that if the hip synovitis did not produce ischaemia of the capital epiphysis, and consequent Perthes’ disease, the tran-
IRRITABLE
HIP
_.__-_
153
sient hip syndrome will not produce future articular pathology. However in 1963 we presented evidence suggesting that in a few patients irreversible changes of the hip joint could occur, leading to degenerative arthritis.3 Among 23 patients examined for an average period of 2 1 years after the transient hip syndrome, we found that 12 of them presented abnormal radiographic changes in the ‘observed’ hip joint, though they were severe in only two patients. It was significant that the more severe sequelae occurred in the older age group (all above 8 years of age). With few exceptions, they also had a more severe clinical picture. That an increase in blood supply to epiphyseal cartilage will stimulate growth is well known. Therefore it is possible that the inflammatory hypervascularity may produce not only a variable degree of osteoporosis, but also a growth stimulus which, if persistent enough, would result in an enlargement of the corresponding epiphysis (coxa magna). Experimental synovitis of the hip joint in growing rabbits] 6 causes enlargements of the cartilaginous parts of the acetabulum, femoral head and neck that could lead to incongruity and subluxation. Widening of the medial joint space, recognised as an early sign of Perthes’ disease has been found to accompany coxa magna in 88% of patients,” and transient synovitis in up to 58”/;;.‘” Increase of the medial joint space of 1 mm or more at admission is considered the most important risk factor for later development of coxa magna. ’ 9 ‘The late occurrence of osteoarthritis in patients with some persistent degree of coxa magna at the end of growth is a logical consequence of the joint incongruity. but it is more difficult to explain in patients with hips of apparently normal configuration. Chondral damage has been demonstrated in experimental synovitis; the increased levels of proteoglycan fragments found in the joint fluid of some children with transient synovitis are comparable to levels found in adults with reactive arthritis.ls It is possible to speculate that some hips with transient synovitis in the older age group would retain some type of cartilage damage that could lead to a type of osteoarthritis, similar to that developing in joints previously affected by acute or chronic inflammation.“’
Relationship to Perthes’ Disease The possible relation between Perthes’ disease and irritable hip has often been considered. Both entities affect children of the same age group with a similar sex distribution. Several authors have reported cases of Perthes’ disease developing several months after an episode of irritable hip, with apparent normality of the hips on plain radiographs. The reported risk” varies between 0 and 17x, and this has encouraged the search for a common patho-
154
CURRENT
ORTHOPAEDICS-MINI-SYMPOSIUM:
THE
genesis, despite the fact that only in 15% of the patients the radiologic diagnosis of Perthes’ disease cannot be made on the first consultation.23 It seems logical to think that if transient synovitis produces a joint effusion with significant pressure, this should be able to produce epiphyseal ischaemia in a joint with a unique vascular anatomy.24 This has been proved to occur experimentally in growing animals.25 Reduced radioisotope uptake has been reported in children with various hip joint disorders such as transient synovitis, septic arthritis and traumatic intracapsular bleeding, but the development of Perthes’ disease has not been reported after infective arthritis or joint haemorrhage. The haemophilic hip joint arthropathy could present temporary Perthes’ like changes, but always evolves to joint destruction and ankylosis. The proportion of patients who develop Perthes’ disease after a clinical episode of irritable hip is very small. Most of the patients with irritable hip will make a permanent recovery without any treatment, and the others will develop a minor degree of coxa magna without proof of any bone necrosis. Recent prospective studies show a nil or minimal incidence of Perthes’ disease developing after transient synovitis and joint effusion proven by sonography and/orjoint aspiration. It seems significant that studies of joint effusion in patients with transient synovitis and Perthes’ disease almost consistently show different characteristics. Intra-capsular pressure is consistently lower in patients with Perthes’ disease and the changes in pressure are less influenced by the position of the hip. The amount of aspirated synovial fluid is rather small, and the concentration of proteoglycan fragments is also considerably lower than in transient synovitis. l l These findings support the opinion that the synovitis present in Perthes’ disease is secondary to the osteochondral lesion. Bone scanning with 99m Tc-MDP and pin-hole collimatortechniqueisthemostreliablewayofdetecting the epiphyseal avascular changes characteristic of the earlier stage of Perthes’disease. Transient synovitis may show initially a decrease in isotope uptake in the proximal femoral epiphysis and even in the growth plate, indicating a disturbance in blood supply during the first week of symptoms. l l This decrease of uptake has been shown to be influenced by the position of extension of the hip and disappears by flexing the hip and also by joint aspiration.*l When symptoms have lasted more than 20-30 days, a reactive hyperaemia with increased isotope uptake is very frequent. Children with Perthes’ disease have a significant retardation of skeletal age and growth,24 while the distribution of skeletal age is normal in patients with transient synovitis.*’ Occurrence of symptomatic transient synovitis on one side and symptoms-free Perthes’ disease on the other have been reported in two patients;** in both cases the hips with synovitis made a permanent recovery.
HIP
IN CHILDHOOD
Bilateral hip disease is also much more frequent in Perthes’ than in transient synovitis. Considering all these facts, it seems logical to think that Perthes’ disease and transient synovitis may be two different diseases, each with its own incidence, occurring in the same age group. Perthes’ disease tends to be considered a focal expression of a general minor disorder of skeletal growth, and the etiology of transient synovitis is unknown, but possibly varied. According to Kallio, *l the rare accidental coincidence of transient synovitis and Perthes’ disease in the same patient appears to be statistically possible.
References 1. Lovett R W, Morse J L. A transient or ephemeral form of hip disease, with a report of cases, Boston Med Surg J 1892; 127: 61-63 2. Ferguson A B. Synovitis of the hip and leg-Perthes’ Disease. Clinical Orthop 1954; 4: 18&188 J A Femandez De. The ‘Observation Hip’ 3. Valderrama syndrome and its late sequelae. J Bone Joint Surg 1963; 45B: 462470 4. Sharwood P P. The irritable hip syndrome. A long-term follow-up. Acta Orthop Stand 1981; 52: 633-638 5. Illingworth C M. Recurrence of transient synovitis of the hip. Arch Dis Child 1983; 58 : 620-623 6. Landin LA, Danielson L G, Wattsgard C. Transient synovitis of the hip. Its incidence, epidemiology and relation to Perthes’ disease. J Bone Joint Surg 1987; 69B: 238-242 I. Miller 0 L. Acute transient epiphysitis of the hip joint. JAMA 1931; 96: 575-519 8. Speck A. Transient synovitis of the hip joint in children. Pediatrics 1959; 24: 1042-1049 9. Hardinge K. The etiology of transient synovitis of the hip in childhood. J Bone Joint Surg 1970; 52B: lO(r107 10. Sainsbury C P Q, Newcombe R G, Essex-Cater A. Irritable hips: Relationship with trauma. Letter, Lancet 1986; January 25; 1 (8474): 220 H. Transient synovitis of the hip in the child. Acta 11. Wingstrand Orthop Stand 1986; Supplementum 219 ~0157 12. Kallio P, Ryiippy S. Hyperpressure in juvenile hip disease. ActaOrthop Stand 1985; $6: 211-214. 13. Sutherland A D. Savage J P. Paterson DC. Foster B K. The nuclide bone s&n in tie diagnosis and management of Perthes’ disease. J Bone Joint Surg 1980; 62B: 300-306 14. Hill SA, Maclamon J C. Ultrasound guided aspiration for transient synovitis of the hip. J Bone Joint Surg 1990; 72B: 852-853 effects on 15. Saxne T, Heineg%rd D, Wollheim F. Therapeutic cartilage metabolism in arthritis as measured by release of proteoglycan structures to the synovial fluid. Ann Rheum Dis 1986; 45: 491497 D H, Ayer A. Synovitis of the hip joint. An 16. Gershuni-Gordon experimental model in rabbits. J Bone Joint Surg 1974; 56B: 69-77 17. Harris L J, Graig W A. Acetabular dysplasia following transient synovitis of the hip. Orthop Rev 1979; 8: I55 18. Sharwood P F. The irritable hip syndrome. A long-term follow up. Acta Orthop Stand 1981; 52: 633-638 19. Kallio P E. Coxa magna following transient synovitis of the hip. Clin Orthop 1988; 228 : 49-56 of the 20. Harrison M H M. Schaiowicz F. Trueta J. Osteoarthritis hip: A study of the natire and evolution of the disease. J Bone Joint Surg 1953; 35B: 598-626 21. Kallio P, RyBppy S. Transient synovitis and Perthes’ disease. J Bone Joint Surg 1986; 68B: 808-811 22. Gonzalez Babe-J, Femandez de Valderrama J A. Perthes’ disease and irritable hip. 1966; Unpublished data of intracapsular 23. Kemp H B S. Perthes’ hisease. Theinfluence tamponade on the circulation in the hip joint of the dog. Clin Orthop 1981; 156: 105-114 24. Harrison M H M, Burwell R G. Perthes’ disease: A concept of pathogenesis. ClinOrthop 1981; 156: 115-127