A nationwide study of Perthes’ disease in Norway was undertaken over a five-year period from January 1996. There were 425 patients registered, which represents a mean annual incidence of 9.2 per 100 000 in subjects under 15 years of age, and an occurrence rate of 1:714 for the country as a whole. There were marked regional variations. The lowest incidence was found in the northern region (5.4 per 100 000 per year) and the highest in the central and western regions (10.8 and 11.3 per 100 000 per year, respectively). There was a trend towards a higher incidence in urban (9.5 per 100 000 per year) compared with rural areas (8.9 per 100 000 per year). The mean age at onset was 5.8 years (1.3 to 15.2) and the male:female ratio was 3.3:1. We compared 402 patients with a matched control group of non-affected children (n = 1 025 952) from the Norwegian Medical Birth Registry and analysed maternal data (age at delivery, parity, duration of pregnancy), birth length and weight, birth presentation, head circumference, ponderal index and the presence of congenital anomalies. Children with Perthes’ disease were significantly shorter at birth and had an increased frequency of congenital anomalies. Applying Sartwell’s log-normal model of incubation periods to the distribution of age at onset of Perthes’ disease showed a good fit to the log-normal curve. Our findings point toward a single cause, either genetic or environmental, acting prenatally in the aetiology of Perthes’ disease

Aims. To explore the of age of onset distribution for Perthes’ disease of the hip, with particular reference to gender, laterality and conformity to the lognormal distribution. Patients and Methods. A total of 1082 patients were identified from the Liverpool Perthes’ Disease Register between 1976 and 2010, of which 992 had the date of diagnosis recorded. In total, 682 patients came from the geographical area exclusively served by Alder Hey Hospital, of which 673 had a date of diagnosis. Age of onset curves were analysed, with respect to the predefined subgroups. Results. The age of onset demonstrated a positive skew with a median of 5.8 years (interquartile range 4.6 to 7.5). Disease onset was a mean five months earlier in girls (p = 0.01) and one year earlier in those who went on to develop bilateral disease (p < 0.001). There was no difference in the age of onset between geographical districts with differing incidence rates. The entire dataset (n = 992) conformed to a lognormal distribution graphically and with the chi-squared test of normality (p = 0.10), but not using the Shapiro-Wilk test (p = 0.01). The distribution for the predefined geographical subgroup (n = 673) conformed well to a lognormal distribution (chi-squared p = 0.16, Shapiro-Wilk p = 0.08). Given the observed lognormal distribution it was assumed that Perthes’ disease followed on incubation period consistent with a point-source disease exposure. The incubation period was further examined using Hirayama’s method, which suggested that the disease exposure may act in the prenatal period. Conclusion. The age of onset in Perthes’ disease conforms to a lognormal distribution, which allows comparisons with infectious disease epidemiology. Earlier onset in girls and those who develop bilateral disease may offer clues to understanding the aetiological determinants of the disease. The analysis suggests that an antenatal aetiological determinant may be responsible for disease. Take home message: Perthes’ disease age of onset conforms to a lognormal model, which is most typical of infectious diseases. The shape of the distribution suggests that an aetiological trigger in the pre-natal period may be an important determinant of disease. Cite this article: Bone Joint J 2016;98-B:710–14

Children presenting with Perthes’ disease before their sixth birthday are considered to have a good prognosis. We describe 166 hips in children in this age group. The mean age at onset of the disease was 44 months (22 to 72). Mild forms (Catterall I and II) were treated conservatively and severe forms (Catterall III and IV) either conservatively or operatively. The aim of the former treatment was to restrict weight-bearing. Operative treatment consisted of innominate osteotomy and was indicated by a Conway type-B appearance on the bone scan. All the patients were followed to skeletal maturity with a mean follow-up of 11 years (8 to 15). The end results were evaluated radiologically using the classifications of Stulberg and Mose. A total of 50 hips were Catterall grade-I or grade-II, 65 Catterall grade-III and 51 Catterall grade-IV. All hips with mild disease had a good result at skeletal maturity. Of the hips with severe disease 78 (67.3%) had good (Stulberg I and II), 26 (22.4%) fair (Stulberg III) and 12 (10.3%) poor results (Stulberg IV and V). Of the Catterall grade-III hips 38 were treated conservatively of which 31 (81.6%) had a good result, six (15.8%) a fair and one (2.6%) a poor result. Operative treatment was carried out on 27 Catterall grade-III hips, of which 21 (77.8%) had a good, four (14.8%) a fair and two (7.4%) a poor result. By comparison conservative treatment of 19 Catterall grade-IV hips led to ten (52.7%) good, seven (36.8%) fair and two (10.5%) poor results. Operative treatment was carried out on 32 Catterall grade-IV hips, of which 16 (50.0%) had a good, nine (28.1%) a fair and seven (21.9%) a poor result. We confirm that the prognosis in Perthes’ disease is generally good when the age at onset is less than six years. In severe disease there is no significant difference in outcome after conservative or operative treatment (p > 0.05). Catterall grade-III hips had a better outcome according to the Stulberg and Mose criteria than Catterall grade-IV hips, regardless of the method of treatment

Aims. The aims of this study were to describe the course of non-operatively managed, bilateral Perthes’ disease, and to determine specific prognostic factors for the radiographic and clinical outcome. . Patients and Methods. We identified 40 children with a mean age of 5.9 years (1.8 to 13.5), who were managed non-operatively for bilateral Perthes’ disease from our prospective, multicentre study of this condition, which included all children in Norway who were diagnosed with Perthes’ disease in the five-year period between 1996 and 2000. All children were followed up for five years. . The hips were classified according to the Catterall classification. A modified three-group Stulberg classification was used as an outcome measure, with a spherical femoral head being defined as a good outcome, an oval head as fair, and a flat femoral head as a poor outcome. . Results. Concurrent, simultaneous bilateral Perthes’ disease was seen in 23 children and 17 had the sequential onset of bilateral disease. The mean delay in onset for the second hip in the latter group was 1.9 years (0.3 to 5.5). . The five-year radiographic outcome was good in 30 (39%), fair in 25 (33%) and poor in 21 (28%) of the hips. The strongest predictors of poor outcome were > 50% necrosis of the femoral head, with odds ratio (OR) 19.6, and age at diagnosis > 6 years (OR 3.3). Other risk factors for poor outcome were the timing of the onset of disease, where children with the sequential onset of bilateral disease had a higher risk than those with the concurrent onset of bilateral disease (p = 0.021, chi-squared test). . Following a diagnosis of Perthes’ disease in one hip, there was a 5% chance of developing it in the contralateral hip. . Conclusion. These results imply that we need to distinguish between children with concurrent onset and those with sequential onset of bilateral Perthes’ disease, as the outcomes may be different. This has not been previously described. Children with concurrent onset of bilateral disease had a similar outcome to our previous series of those with unilateral disease, whereas children with sequential onset of bilateral disease had a worse prognosis. The increased risk of developing Perthes’ disease in the contralateral hip in those with unilateral disease is important information for the child and parents. . Cite this article: Bone Joint J 2016;98-B:569–75

The purpose of this study was to determine the annual incidence of Perthes’ disease in Korea and compare this with other populations. A survey identified all newly diagnosed children with Perthes’ disease aged 14 years or younger in South Honam, Korea, between January 1999 and December 2001. A total of 84 children were included: 29 in 1999, 28 in 2000 and 27 in 2001. The mean annual incidence was 3.8 per 100 000. This is similar to that reported in other Asian countries, but higher than in black populations and lower than in Caucasians

We studied 16 patients suffering from osteoarthritis of the hip who had had Perthes’ disease during childhood. They were compared clinically and radiologically with a control group who had not had Perthes’ disease, in order to assess whether a generalised, pre-existing constitutional disorder was present. Nine patients with a previous history of Perthes’ disease had some other skeletal abnormality, but only three presented with clinical symptoms. Only one patient in the control group was found to have an abnormality but was symptom-free. Our findings provide further evidence that patients with Perthes’ disease may have a generalised abnormality related to chondrogenesis which can produce other skeletal anomalies that persist into adult life

This nationwide prospective study was designed to determine prognostic factors and evaluate the outcome of different treatments of Perthes’ disease. A total of 28 hospitals in Norway were instructed to report all new cases of Perthes’ disease over a period of five years and 425 patients were reported and followed for five years. Of these, 368 with unilateral disease were included in the present study. The hips were classified radiologically according to a modified two-group Catterall classification and the lateral pillar classification. A total of 358 patients (97%) attended the five-year follow-up, when a modified three-group Stulberg classification was used as a radiological outcome measure. For patients over six years of age at diagnosis and with more than 50% necrosis of the femoral head (152 patients), the surgeons at the different hospitals had chosen one of three methods of treatment: physiotherapy (55 patients), the Scottish Rite abduction orthosis (26), and proximal femoral varus osteotomy (71). Of these hips, 146 (96%) were available for the five-year follow-up. The strongest predictor of outcome was femoral head involvement of more or less than 50% (odds ratio (OR) = 7.76, 95% confidence interval (CI) 2.82 to 21.37), followed by age at diagnosis (OR = 0.98, 95% CI 0.92 to 0.99) and the lateral pillar classification (OR = 0.62, 95% CI 0.40 to 0.98). In children over six years at diagnosis with more than 50% of femoral head necrosis, proximal femoral varus osteotomy gave a significantly better outcome than orthosis (p = 0.001) or physiotherapy (p = 0.001). There was no significant difference between the physiotherapy and orthosis groups (p = 0.36), and we found no difference in outcome after any of the treatments in children under six years (p = 0.73). We recommend proximal femoral varus osteotomy in children aged six years and over at the time of diagnosis with hips having more than 50% femoral head necrosis. The abduction orthosis should be abandoned in Perthes’ disease

The deformity index is a new radiological measurement of the degree of deformity of the femoral head in unilateral Perthes’ disease. Its values represent a continuous outcome measure of deformity incorporating changes in femoral epiphyseal height and width compared with the unaffected side. The sphericity of the femoral head in 30 radiographs (ten normal and 20 from patients with Perthes’ disease) were rated blindly as normal, mild, moderate or severe by three observers. Further blinded measurements of the deformity index were made on two further occasions with intervals of one month. There was good agreement between the deformity index score and the subjective grading of deformity. Intra- and interobserver agreement for the deformity index was high. The intraobserver intraclass correlation coefficient for each observer was 0.98, 0.99 and 0.97, respectively, while the interobserver intraclass correlation coefficient was 0.98 for the first and 0.97 for the second set of calculations. We also reviewed retrospectively 96 radiographs of children with Perthes’ disease, who were part of a multicentre trial which followed them to skeletal maturity. We found that the deformity index at two years correlated well with the Stulberg grading at skeletal maturity. A deformity index value above 0.3 was associated with the development of an aspherical femoral head. Using a deformity index value of 0.3 to divide groups for risk gives a sensitivity of 80% and specificity of 81% for predicting a Stulberg grade of III or IV. We conclude that the deformity index at two years is a valid and reliable radiological outcome measure in unilateral Perthes’ disease

It has been shown that in the puppy, two infarcts separated by an interval of four weeks produce a disorder of long duration which results in flattening and broadening of the femoral head and which reproduces the radiological changes seen in Perthes' disease in man. The histological appearances produced by two infarcts are characteristic. In this study the histological appearance of fifty-seven femoral head biopsy specimens in Perthes' disease in man have been studied. In 51 per cent of hips histopathological changes characteristic of double infarction were present, and there were grounds for postulating that double infarction might eventually occur in all cases. The findings support the concept that the deformation of the femoral head and the chronicity of Perthes' disease in man may be due at least as much or even more to repeated episodes of infarction and the ensuing abnormalities of growth as to mechanical factors related to weight-bearing

1. Perthes' disease is an ischaemic lesion of the ossific nucleus of the head of the femur which may vary both in extent and degree. It is probably never quite complete. 2. When part of the ossific nucleus only is affected, as is usually the case, it is almost invariably the antero-lateral part. 3. The process of absorption of the damaged bone is complete radiologically before there is radiological evidence of reossification. 4. Reossification always occurs in Perthes' disease. 5. The aim of treatment must be to see that the mould in which the head is shaped is the right shape when ossification occurs. 6. The deformity of the head of the femur does not occur from pressure alone, but from pressure combined with subluxation. Full unrestricted weight-bearing can be allowed with safety on a femoral head in which there are ischaemic changes provided the femoral head is well contained. 7. The time of treatment can be very greatly reduced by using operation to correct the subluxation instead of relying on external splintage. This can be achieved by subtrochanteric osteotomy with rotation, or rotation combined with varus angulation. 8. Perthes' disease and avascular necrosis of the head of the femur are different conditions with different characteristics. 9. Suggestions are made as to the nature of the disease in relation to absorption, continued growth and reossification

Recent reports have suggested an association between Perthes’ disease and an underlying thrombophilic or hypofibrinolytic tendency. In Northern Ireland there is a high incidence of Perthes’ disease (11.7 per 100 000 or 1 in 607 children) in a stable paediatric population. We reviewed 139 children with Perthes’ disease and compared them with a control group of 220 aged- and gender-matched healthy primary schoolchildren with similar racial and ethnic backgrounds. There were no significant deficiencies of antithrombotic factors protein C, protein S, antithrombin III or resistance to activated protein C. A total of 53 (38.1%) of the children with Perthes’ disease had a prolonged activated partial thromboplastin time (> 38) compared with 13 (5.9%) of the control group (p < 0.001). Our findings have shown that using standard assays, thrombophilia secondary to antithrombotic factor deficiency or resistance to activated protein does not appear to be an aetiological factor for Perthes’ disease. The cause of the prolonged activated partial thromboplastin time, usually associated with a clotting factor deficiency, is under further investigation

Radiographs of 155 Indian children were examined to identify the acetabular changes which occur in Perthes' disease. These changes included osteoporosis of the acetabular roof, irregularity of contour, premature fusion of the triradiate cartilage, hypertrophy of articular cartilage and changes in dimensions. These changes tended to be more marked in older children and when more than half of the femoral epiphysis was involved. Comparison with 25 cases of Perthes' disease from Liverpool showed the same picture. Several of the acetabular changes noted during the active stages were also seen in a series of 24 adult hips after Perthes' disease. Radio-isotope scans of the hips of 27 children with Perthes' disease showed a consistently increased uptake in the acetabulum on the affected side, indicative of a local increase in vascularity and metabolic activity. It was possible to postulate a working model for the pathogenesis of all the acetabular changes. A number of statistical correlations suggest that most of the changes have a bearing on the final outcome

Perthes' disease is common in certain urban areas within Britain. It is one manifestation of a generalised growth disorder and nutritional causes are suspected. Orthopaedic surgeons throughout the Yorkshire region recorded all new patients with Perthes' disease over two years. There were large geographical differences in incidence which could not be explained by urban-rural or social class differences. No cases were recorded in a large area within the eastern part of the region, which is in high-grade farming land and has had a relatively low infant mortality throughout this century

The radiographs of 153 children suffering from Perthes' disease of one hip were studied to examine the bony outline of the femoral capital epiphysis in the unaffected hip. In 48.4 per cent of patients irregularity of the surface, flattening or dimpling, were noted; in the majority of instances (37.2 per cent) these changes were present in the initial anteroposterior radiograph. By contrast, these changes were present in only 10.4 per cent of a control series of 153 children in whom intravenous urography was being performed, these children being matched for age and sex with the children with Perthes' disease. A second unmatched control series of 49 children whose pelves were being radiographed after injury showed a 6.1 per cent incidence of contour irregularities in 98 femoral capital epiphyses. In the patients with Perthes' disease and in the control series obtained at urography the incidence of changes was inversely related to age. The possible cause and significance of contour irregularities in normal children and in those with Perthes' disease is disscussed

There is a high incidence of Perthes' disease among the children of unskilled manual workers in underprivileged urban areas in Britain. The skeletal measurements of 38 Liverpool children with Perthes' disease were compared with those of their siblings and of normal children from the inner and outer city. Children in families where Perthes' disease occurs have retarded growth of the trunk, with reduced sitting height and bi-acromial diameter. Among those who develop the disease there is also retarded limb growth, most evident as unusually small feet

We used ultrasonography to examine 36 children suffering from transient synovitis and 12 children with early Perthes' disease. Widening of the joint space was revealed by ultrasonography in all affected hips with either disease. In the patients with transient synovitis, capsular distension was attributed to synovial effusion, while in the patients with Perthes' disease it was produced by thickening of the synovial membrane. Neither capsular distension nor thickening of the joint cartilage was seen in the contralateral normal hip in the patients with transient synovitis, but they were common in early Perthes' disease. Ultrasonography may provide significant diagnostic clues to differentiate early Perthes' from transient synovitis

A prospective study was made of 119 children with transient synovitis or any other cause for synovial effusion and elevated intra-articular pressure. During a follow-up of one year not one case of Perthes' disease was diagnosed and the late clinical and radiographic changes were minimal with moderate overgrowth of the femoral head in 33% and widening of the joint space in 14.2%. Our results do not support the widely accepted concept that Perthes' disease develops as a result of the period of elevated intra-articular pressure found in transient synovitis. Further research into this and Perthes' disease should follow the premise that they are two different diseases without any aetiological connection

Serum immunoglobulin concentrations in 41 children with Perthes' disease and 82 age and sex matched controls were measured by radial immunodiffusion. Significant increases in IgG and IgM were seen in children with Perthes' disease

It has been suggested that Perthes’ disease is more prevalent in urban areas, and that the risk increases with deprivation. We present the findings of a preliminary analysis of Perthes’ disease in Northern Ireland, which is shown to have one of the highest national annual rates of incidence in the world (11.6 per 100 000). Of the 313 children diagnosed over a seven-year period, 311 were allocated to the enumeration districts of the 1991 census, thus allowing the incidence to be calculated using both spatial and non-spatial aggregation. The cases were grouped according to the size of the settlement from highly urbanised to open countryside and by level of area deprivation. While the incidence of Perthes’ disease was found to be associated with indicators of the level of deprivation for areas, there was no evidence to suggest that there was an increased risk in urban areas; the highest rate was found in the most deprived rural category

Recent work has suggested that thrombophilia may be an aetiological factor in up to 50% of children with Perthes’ disease, and that up to 75% may have a coagulopathy. Our aim was to test these findings in the local population of children with Perthes’ disease and attempt to correlate them with the severity of the condition. In 64 children there were only eight (12%) with low levels of clotting proteins, as defined by normal paediatric ranges. Of these eight, only five could be said to show any thrombophilic tendency