Aims. To identify a suite of the key physical, emotional, and social outcomes to be employed in clinical practice and research concerning Perthes' disease in children. Methods. The study follows the guidelines of the COMET-Initiative (Core Outcome Measures in Effectiveness Trials). A systematic review of the literature was performed to identify a list of outcomes reported in previous studies, which was supplemented by a qualitative study exploring the experiences of families affected by Perthes’ disease. Collectively, these outcomes formed the basis of a Delphi survey (two rounds), where 18 patients with Perthes’ disease, 46 parents, and 36 orthopaedic surgeons rated each outcome for importance. The International Perthes Study Group (IPSG) (Dallas, Texas, USA (October 2018)) discussed outcomes that failed to reach any consensus (either ‘in’ or ‘out’) before a final consensus meeting with representatives of surgeons, patients, and parents. Results. In total, 23 different outcome domains were identified from the systematic review, and a further ten from qualitative interviews. After round one of the Delphi survey, participants suggested five further outcome domains. A total of 38 outcomes were scored in round two of the Delphi. Among these, 16 outcomes were scored over the prespecified 70% threshold for importance (divided into six main categories: adverse events; life impact; resource use; pathophysiological manifestations; death; and technical considerations). Following the final consensus meeting, 14 outcomes were included in the final Core Outcome Set (COS). Conclusion. Core Outcome Sets (COSs) are important to improve standardization of outcomes in clinical research and to aid communication between patients, clinicians, and funding bodies. The results of this study should be a catalyst to develop high-quality clinical research in order to determine the optimal treatments for children with Perthes’ disease. Cite this article: Bone Joint J 2020;102-B(5):611–617

Aims. The aim of this study was to produce clinical consensus recommendations about the non-surgical treatment of children with Perthes’ disease. The recommendations are intended to support clinical practice in a condition for which there is no robust evidence to guide optimal care. Methods. A two-round, modified Delphi study was conducted online. An advisory group of children’s orthopaedic specialists consisting of physiotherapists, surgeons, and clinical nurse specialists designed a survey. In the first round, participants also had the opportunity to suggest new statements. The survey included statements related to ‘Exercises’, ‘Physical activity’, ‘Education/information sharing’, ‘Input from other services’, and ‘Monitoring assessments’. The survey was shared with clinicians who regularly treat children with Perthes’ disease in the UK using clinically relevant specialist groups and social media. A predetermined threshold of ≥ 75% for consensus was used for recommendation, with a threshold of between 70% and 75% being considered as ‘points to consider’. Results. A total of 40 participants took part in the first round, of whom 31 completed the second round. A total of 87 statements were generated by the advisory group and included in the first round, at the end of which 31 achieved consensus and were removed from the survey, and an additional four statements were generated. A total of 60 statements were included in the second round and 45 achieved the threshold for consensus from both rounds, with three achieving the threshold for ‘points to consider’. The recommendations predominantly included self-management, particularly relating to advice about exercise and education for children with Perthes’ disease and their families. Conclusion. Children’s orthopaedic specialists have reached consensus on recommendations for non-surgical treatment in Perthes’ disease. These statements will support decisions made in clinical practice and act as a foundation to support clinicians in the absence of robust evidence. The dissemination of these findings and the best way of delivering this care needs careful consideration, which we will continue to explore. Cite this article: Bone Joint J 2024;106-B(5):501–507

Aims. This study aimed to evaluate the relationship between hip shape and mid-term function in Perthes’ disease. It also explored whether the modified three-group Stulberg classification can offer similar prognostic information to the five-group system. Methods. A total of 136 individuals aged 12 years or older who had Perthes’ disease in childhood completed the Patient-Reported Outcomes Measurement Information System (PROMIS) Mobility score (function), Nonarthritic Hip Score (NAHS) (function), EuroQol five-dimension five-level questionnaire (EQ-5D-5L) score (quality of life), and the numeric rating scale for pain (NRS). The Stulberg class of the participants’ hip radiographs were evaluated by three fellowship-trained paediatric orthopaedic surgeons. Hip shape and Stulberg class were compared to PROM scores. Results. A spherical hip was associated with the highest function and quality of life, and lowest pain. Conversely, aspherical hips exhibited the lowest functional scores and highest pain. The association between worsening Stulberg class (i.e. greater deviation from sphericity) and worse outcome persisted after adjustment for age and sex in relation to PROMIS (predicted mean difference -1.77 (95% confidence interval (CI) -2.70 to -0.83)), NAHS (-5.68 (95% CI -8.45 to -2.90)), and NRS (0.61 (95% CI 0.14 to 1.08)), but not EQ-5D-5L (-0.03 (95% CI -0.72 to 0.11)). Conclusion. Patient-reported outcomes identify lower function, quality of life, and higher pain in aspherical hips. The magnitude of symptoms deteriorated with time. Hip sphericity (i.e. the modified three-group classification of spherical, oval, and aspherical) appeared to offer similar levels of detail to the five-group Stulberg classification. Cite this article: Bone Joint J 2023;105-B(6):711–716

Aims. The aim of this study was to assess the prognostic value of the modified three-group Stulberg classification, which is based on the sphericity of the femoral head, in patients with Perthes’ disease. Methods. A total of 88 patients were followed from the time of diagnosis until a mean follow-up of 21 years. Anteroposterior pelvic and frog-leg lateral radiographs were obtained at diagnosis and at follow-up of one, five, and 21 years. At the five- and 21-year follow-up, the femoral heads were classified using a modified three-group Stulberg classification (round, ovoid, or flat femoral head). Further radiological endpoints at long-term follow-up were osteoarthritis (OA) of the hip and the requirement for total hip arthroplasty (THA). Results. There were 71 males (81%) and 17 females. A total of 13 patients had bilateral Perthes’ disease; thus 101 hips were analyzed. At five-year follow-up, 37 hips were round, 38 ovoid, and 26 flat. At that time, 66 hips (65%) were healed and 91 (90%) were skeletally immature. At long-term follow-up, when the mean age of the patients was 28 years (24 to 34), 20 hips had an unsatisfactory outcome (seven had OA and 13 had required THA). There was a strongly significant association between the modified Stulberg classification applied atfive-year follow-up and an unsatisfactory outcome at long-term follow-up (p < 0.001). Between the five- and 21-year follow-up, 67 hips (76%) stayed in their respective modified Stulberg group, indicating a strongly significant association between the Stulberg classifications at these follow-ups (p < 0.001). Conclusion. The modified Stulberg classification is a strong predictor of long-term radiological outcome in patients with Perthes’ disease. It can be applied at the healing stage, which is usually reached five years after the diagnosis is made and before skeletal maturity. Cite this article: Bone Joint J 2021;103-B(12):1815–1820

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

Aims. Modular or custom-made femoral components have been preferred for total hip arthroplasty (THA) in patients with a history of Perthes’ disease because of the distortion in the anatomy of the proximal femur. However, it has not been established whether a monobloc cementless stem will fit the distorted proximal femur or whether the results of the procedure are satisfactory in this group of patients. Patients and Methods. We reviewed 68 consecutive patients who had undergone THA for childhood Perthes’ disease between June 2003 and December 2008. There were 35 men and 33 women with a mean age of 48 years (16 to 73) at the time of index arthroplasty. Their mean body mass index was 24.4 (18.3 to 32.9). Of the 68 hips, 32 were classified as Stulberg class III and 36 as class IV. The mean pre-operative shortening of the affected leg was 17.2 mm (5 to 34). The minimum follow-up was five years (mean 8.5 years; 5.2 to 10). Results. An intra-operative calcar fracture occurred in eight hips (11.8%) and was successfully treated by cerclage wiring. The mean stem version was 14.6° (-2.3 to 30; standard deviation (. sd. ) 7.3). The mean acetabular component abduction was 40.2° (23.7 to 56.0; . sd. 6.5) and the mean anteversion 28.3° (6.4 to 43.0; . sd. 7.6), respectively. The mean follow-up was 8.5 years (5.2 to 10). No dislocations occurred and no hips were revised during the course of the study. At final follow-up, the mean Harris Hip Score was 91 points (59 to 100) and the mean University of California, Los Angeles activity score was 3.2 (2 to 8). Conclusion. Monobloc cementless stems reliably restore the anatomy in Perthes’ disease at THA without the need for custom-made or modular implants. Cite this article: Bone Joint J 2017;99-B:440–444

This paper reports a high incidence of minor congenital anomalies in boys and girls with Perthes' disease compared with that in a control population. There is a similarity of the incidence of minor anomalies in the children with Perthes' disease to that in babies with a single major congenital defect. Multiple major defects were more numerous and more severe than in the control children. It is speculated that there may be a congenital abnormality affecting skeletal development which in some way makes the hip susceptible to Perthes' disease at a later date

Aims. The aim of this study was to evaluate the epidemiology and treatment of Perthes’ disease of the hip. Methods. This was an anonymized comprehensive cohort study of Perthes’ disease, with a nested consented cohort. A total of 143 of 144 hospitals treating children’s hip disease in the UK participated over an 18-month period. Cases were cross-checked using a secondary independent reporting network of trainee surgeons to minimize those missing. Clinician-reported outcomes were collected until two years. Patient-reported outcome measures (PROMs) were collected for a subset of participants. Results. Overall, 371 children (396 hips) were newly affected by Perthes’ disease arising from 63 hospitals, with a median of two patients (interquartile range 1.0 to 5.5) per hospital. The annual incidence was 2.48 patients (95% confidence interval (CI) 2.20 to 2.76) per 100,000 zero- to 14-year-olds. Of these, 117 hips (36.4%) were treated surgically. There was considerable variation in the treatment strategy, and an optimized decision tree identified joint stiffness and age above eight years as the key determinants for containment surgery. A total of 348 hips (88.5%) had outcomes to two years, of which 227 were in the late reossification stage for which a hip shape outcome (Stulberg grade) was assigned. The independent predictors of a poorer radiological outcome were female sex (odds ratio (OR) 2.27 (95% CI 1.19 to 4.35)), age above six years (OR 2.62 (95% CI (1.30 to 5.28)), and over 50% radiological collapse at inclusion (OR 2.19 (95% CI 0.99 to 4.83)). Surgery had no effect on radiological outcomes (OR 1.03 (95% CI 0.55 to 1.96)). PROMs indicated the marked effect of the disease on the child, which persisted at two years. Conclusion. Despite the frequency of containment surgery, we found no evidence of improved outcomes. There appears to be a sufficient case volume and community equipoise among surgeons to embark on a randomized clinical trial to definitively investigate the effectiveness of containment surgery. Cite this article: Bone Joint J 2022;104-B(4):510–518

Perthes’ disease is an osteonecrosis of the juvenile hip, the aetiology of which is unknown. A number of comorbid associations have been suggested that may offer insights into aetiology, yet the strength and validity of these are unclear. This study explored such associations through a case control study using the United Kingdom General Practice Research database. Associations investigated were those previously suggested within the literature. A total of 619 cases of Perthes’ disease were included, as were 2544 controls. The risk of Perthes’ disease was significantly increased with the presence of congenital anomalies of the genitourinary and inguinal region, such as hypospadias (odds ratio (OR) 4.04 (95% confidence interval (CI) 1.41 to 11.58)), undescended testis (OR 1.83 (95% CI 1.12 to 3.00)) and inguinal herniae (OR 1.79 (95% CI 1.02 to 3.16)). Attention deficit hyperactivity disorder was not associated with Perthes’ disease (OR 1.01 (95% CI 0.48 to 2.12)), although a generalised behavioural disorder was (OR 1.55 (95% CI 1.10 to 2.17)). Asthma significantly increased the risk of Perthes’ disease (OR 1.44 (95% CI 1.17 to 1.76)), which remained after adjusting for oral/parenteral steroid use. Perthes’ disease has a significant association with congenital genitourinary and inguinal anomalies, suggesting that intra-uterine factors may be critical to causation. Other comorbid associations may offer insight to support or refute theories of pathogenesis

The role of heritable thrombophilic risk factors in the pathogenesis of the Perthes’ disease is controversial. The clinical and radiological findings of Perthes’ disease may be indistinguishable from those of Gaucher’s disease, and the most common Jewish N370S Gaucher mutation is threefold greater in patients with Perthes’ disease. Familial osteonecrosis of the femoral head is associated with variant mutations of collagen type II (COL2A1 mutations). We therefore studied the potential role of genetic thrombophilia and the Gaucher and COL2A1 mutations in children with Perthes’ disease. Genomic DNA of 119 children with radiologically-confirmed Perthes’ disease diagnosed between 1986 and 2005 was analysed for the thrombophilic polymorphisms Factor V Leiden, 677T-MTHFR and FIIG20210A. The results were compared with those of a group of 276 children without Perthes’ disease. DNA was also analysed for the Gaucher mutations N370S, G insertion (84GG), L444P, Intron 2 (IVS2+1G> A) and R496H. Enzymic assays confirmed the Gaucher disease status. Collagen (COL2A1) mutations of the 12q13 gene were also analysed. The prevalence of thrombophilic markers was similar among the 119 patients with Perthes’ disease and the 276 control subjects. The prevalence of the Gaucher mutation was consistent with Israeli population carriership data and did not confirm an earlier-claimed association with Perthes’ disease. All 199 patients were negative for the studied COL2A1 mutations. We found no genetic association between Perthes’ disease and either Gaucher’s disease or COL2A1 mutations or increased genetic thrombophilia among our patients compared with the control group. A systematic review of case-control studies suggested that there was a positive association between Perthes’ disease and Factor V Leiden. The impact of this association upon the disease, although not consistent across the studies, remains unclear

Aims. Ganz’s studies made it possible to address joint deformities on both the femoral and acetabular side brought about by Perthes’ disease. Femoral head reduction osteotomy (FHRO) was developed to improve joint congruency, along with periacetabular osteotomy (PAO), which may enhance coverage and containment. The purpose of this study is to show the clinical and morphological outcomes of the technique and the use of an implemented planning approach. Methods. From September 2015 to December 2021, 13 FHROs were performed on 11 patients for Perthes’ disease in two centres. Of these, 11 hips had an associated PAO. A specific CT- and MRI-based protocol for virtual simulation of the corrections was developed. Outcomes were assessed with radiological parameters (sphericity index, extrusion index, integrity of the Shenton’s line, lateral centre-edge angle (LCEA), Tönnis angle), and clinical parameters (range of motion, visual analogue scale (VAS) for pain, Merle d'Aubigné-Postel score, modified Harris Hip Score (mHHS), and EuroQol five-dimension five-level health questionnaire (EQ-5D-5L)). Early and late complications were reported. Results. The mean follow-up was 39.7 months (standard deviation (SD) 26.4). The mean age at surgery was 11.4 years (SD 1.6). No major complications were recorded. One patient required a total hip arthroplasty. Mean femoral head sphericity increased from 46.8% (SD 9.34%) to 70.2% (SD 15.44; p < 0.001); mean LCEA from 19.2° (SD 9.03°) to 44° (SD 10.27°; p < 0.001); mean extrusion index from 37.8 (SD 8.70) to 7.5 (SD 9.28; p < 0.001); and mean Tönnis angle from 16.5° (SD 12.35°) to 4.8° (SD 4.05°; p = 0.100). The mean VAS improved from 3.55 (SD 3.05) to 1.22 (1.72; p = 0.06); mean Merle d’Aubigné-Postel score from 14.55 (SD 1.74) to 16 (SD 1.6; p = 0.01); and mean mHHS from 60.6 (SD 18.06) to 81 (SD 6.63; p = 0.021). The EQ-5D-5L also showed significant improvements. Conclusion. FHRO associated with periacetabular procedures is a safe technique that showed improved functional, clinical, and morphological outcomes in Perthes’ disease. The newly introduced simulation and planning algorithm may help to further refine the technique. Cite this article: Bone Joint J 2024;106-B(5 Supple B):40–46

It has been reported that there is an association between Perthes’ disease and poverty. We examined the demographic data of a group of 240 children (263 hips) who presented with Perthes’ disease in Greater Glasgow, where the mean deprivation scores are substantially greater than in the rest of Scotland, to see if this association applied and whether other clues to the aetiology of Perthes’ disease could be found. There were 197 boys and 43 girls; 39 (16.25%) had a family history of Perthes’ disease. Bone age in this series was heavily skewed towards the lower percentiles. The mean number of siblings was 1.9, with 31 (12.9%) being an only child. Maternal age at the birth of the first child showed no preponderance of older mothers. Maternal smoking during and after pregnancy was noted in 132 (55%), which compared with the 52% reported in the population of Greater Glasgow in general. Of the children in our series, 60 (25%) were in social class IV and V. However, this applies to more than half of the population of Greater Glasgow. There was no significant evidence of a preponderance of Perthes’ disease in the most deprived groups. The aetiology of Perthes’ disease is likely to be multifactorial and may include a genetic or deprivation influence resulting in delayed bone age

We have investigated the annual incidence of Perthes’ disease in Dumfries and Galloway (Southwest Scotland), in relation to the population density and socio-economic status. The incidence of Perthes’ disease in rural Scotland is comparable with that in urban areas (15.4 per 100 000). There was a direct association between the incidence of Perthes’ disease and deprivation scores, with the highest incidence in the most deprived areas. A higher incidence of Perthes’ disease was noted in areas with a lower population density compared with those with a higher density. We found no correlation between population density and deprivation scores for individual electoral wards within the region

Our aim was to investigate the relationship between urinary excretion of deoxypyridinoline (DPD) as a marker of bone resorption, and Perthes’ disease. There were 39 children with Perthes’ disease in the florid stage who collected first-morning urine samples at regular intervals of at least three months. The level of urinary DPD was analysed by chemiluminescence immunoassay and was correlated with the radiological stage of the disease as classified by Waldenström, and the severity of epiphyseal involvement according to the classification systems of Catterall and Herring. The urinary DPD levels of a group of 44 healthy children were used as a control. The median urinary DPD/creatinine (CREA) ratio was significantly reduced (p < 0.0001) in the condensation stage and increased to slightly elevated values at the final stage (p = 0.05) when compared with that of the control group. Herring-C patients showed significantly lower median DPD/CREA ratios than Herring-B patients (p = 0.03). The significantly decreased median DPD/CREA ratio in early Perthes’ disease indicated a reduced bone turnover and supports the theory of a systemic aetiology. Urinary levels of DPD may therefore be used to monitor the course of Perthes’ disease

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. Perthes’ disease (PD) is a childhood hip disorder that can affect the quality of life in adulthood due to femoral head deformity and osteoarthritis. There is very little data on how PD patients function as adults, especially from the patients’ perspective. The purpose of this study was to collect treatment history, demographic details, the University of California, Los Angeles activity score (UCLA), the 36-Item Short Form survey (SF-36) score, and the Hip disability and Osteoarthritis Outcome score (HOOS) of adults who had PD using a web-based survey method and to compare their outcomes to the outcomes from an age- and sex-matched normative population. Methods. The English REDCap-based survey was made available on a PD study group website. The survey included childhood and adult PD history, UCLA, SF-36, and HOOS. Of the 1,182 participants who completed the survey, the 921 participants who did not have a total hip arthroplasty are the focus of this study. The mean age at survey was 38 years (SD 12) and the mean duration from age at PD onset to survey participation was 30.8 years (SD 12.6). Results. In comparison to a normative population, the PD participants had significantly lower HOOS scores across all five scales (p < 0.001) for all age groups. Similarly, SF-36 scores of the participants were significantly lower (p < 0.001) for all scales except for age groups > 55 years. Overall, females, obese participants, those who reported no treatment in childhood, and those with age of onset > 11 years had significantly worse SF-36 and HOOS scores. Pairwise correlations showed a strong positive correlation within HOOS scales and between HOOS scales and SF-36 scales, indicating construct validity. Conclusion. Adult PD participants had significantly worse pain, physical, mental, and social health than an age- and sex-matched normative cohort. The study reveals a significant burden of disease on the adult participants of the survey, especially females. Cite this article: Bone Joint J 2022;104-B(12):1304–1312

Aims. Perthes’ disease (PD) often results in femoral head deformity and leg length discrepancy (LLD). Our objective was to analyze femoral morphology in PD patients at skeletal maturity to assess where the LLD originates, and evaluate the effect of contralateral epiphysiodesis for length equalization on proximal and subtrochanteric femoral lengths. Methods. All patients treated for PD in our institution between January 2013 and June 2020 were reviewed retrospectively. Patients with unilateral PD, LLD of ≥ 5 mm, and long-leg standing radiographs at skeletal maturity were included. Total leg length, femoral and tibial length, articulotrochanteric distance (ATD), and subtrochanteric femoral length were compared between PD side and the unaffected side. Furthermore, we compared leg length measurements between patients who did and who did not have a contralateral epiphysiodesis. Results. Overall, 79 patients were included, of whom 21 underwent contralateral epiphysiodesis for leg length correction. In the complete cohort, the mean LLD was 1.8 cm (95% confidence interval (CI) 1.5 to 2.0), mean ATD difference was 1.8 cm (95% CI -2.1 to -1.9), and mean subtrochanteric difference was -0.2 cm (95% CI -0.4 to 0.1). In the epiphysiodesis group, the mean LLD before epiphysiodesis was 2.7 cm (95% CI 1.3 to 3.4) and 1.3 cm (95% CI -0.5 to 3.8) at skeletal maturity. In the nonepiphysiodesis group the mean LLD was 2.0 cm (95% CI 0.5 to 5.1; p = 0.016). The subtrochanteric region on the PD side was significantly longer at skeletal maturity in the epiphysiodesis group compared to the nonepiphysiodesis group (-1.0 cm (95% CI -2.4 to 0.6) vs 0.1 cm (95% CI -1.0 to 2.1); p < 0.001). Conclusion. This study demonstrates that LLD after PD originates from the proximal segment only. In patients who had contralateral epiphysiodesis to balance leg length, this is achieved by creating a difference in subtrochanteric length. Arthroplasty surgeons need to be aware that shortening of the proximal femur segment in PD patients may be misleading, as the ipsilateral subtrochanteric length in these patients can be longer. Therefore, we strongly advise long-leg standing films for THA planning in PD patients in order to avoid inadvertently lengthening the limb. Cite this article: Bone Joint J 2021;103-B(11):1736–1741

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

Skeletal age was estimated by examination of radiographs of the carpus in 182 children suffering from Perthes' disease after the reliability of the Greulich and Pyle Atlas had been checked for a control group of British children. A striking tendency to delayed skeletal maturation was shown in the children with Perthes' disease. This trait was also found in ninety-three unaffected siblings of the patients. The velocity of skeletal ageing as the disease progressed was estimated. In some patients the carpal skeleton failed to mature at all for periods of up to three years and the term "skeletal standstill" is applied to this phenomenon. The significance of these findings is discussed and it is suggested that the maturation defect may have aetiological significance

The bicompartmental acetabulum is one of the morphological changes which may be seen in children with Legg-Calvé-Perthes’ disease. Three-dimensional CT and MRI were used to analyse the detailed morphology of the acetabulum with special reference to its inner surface, in 16 patients with Perthes’ disease and a bicompartmental acetabulum. The bicompartmental appearance was seen on the coronal plane image through the acetabular fossa. The lunate surface was seen to grow laterally resulting in an increased mediolateral thickness of the triradiate cartilage. On the horizontal plane images, the acetabular fossa had deepened and had a distinct prominence at its posterior border. The combination of these morphological changes resulted in a bicompartmental appearance on plain radiography. Acetabular bicompartmentalisation appears to be the result of an imbalance of growth between the cartilage-covered lunate surface and the cartilage-devoid acetabular fossa

We performed superselective angiography in 28 hips in 25 patients with Perthes’ disease in order to study the blood supply of the lateral epiphyseal arteries (LEAs). Interruption of the LEAs at their origin was observed in 19 hips (68%). Revascularisation in the form of numerous small arteries was seen in ten out of 11 hips in the initial stage of Perthes’ disease, in seven of eight in the fragmentation stage and in five of nine in the healing stage. Penetration of mature arteries into the depths of the epiphysis was seen in four of nine hips in the healing stage. Vascular penetration was absent in the weight-bearing portion of the femoral head below the acetabular roof. Interruption of the posterior column artery was seen where it passed through the capsule in seven hips when they lay either in internal rotation or in abduction with internal rotation. We suggest that in Perthes’ disease the blood supply of the LEAs is impaired at their origin and that revascularisation occurs from this site by ingrowth of small vessels into the femoral epiphysis. This process may be the result of recurrent ischaemic episodes

1. The findings in a femoral head obtained at necropsy on a boy aged nine suffering from Perthes' disease are described. 2. The findings revealed that there had been avascular necrosis of the epiphysis followed by revascularisation and healing, and there was evidence to suggest a second episode of infarction. 3. The findings provide strong support for the suggestion that Perthes' disease is the result not of one but of more than one episode of major infarction

We treated 98 consecutive patients with Perthes’ disease by a unilateral brace in external rotation, flexion and abduction and a further consecutive 110 by a bilateral cast with the hips in internal rotation and abduction. During treatment in the unilateral brace, six (6.1%) hips on the opposite side developed evidence of Perthes’ disease and one developed this after the brace had been removed. In children managed in bilateral casts, no contralateral Perthes’ disease was seen. Adequate containment of the femoral head may prevent subsequent changes in the opposite hip

The nuclide bone-scan will reliably diagnose Perthes' disease with a sensitivity of 0.98 and a specificity of 0.95. The comparable figures for radiographic sensitivity and specificity are respectively 0.92 and 0.78. In addition, it is possible on the scan to recognise the onset of revascularisation of the femoral capital epiphysis some months before there are radiographic signs of new bone formation. Scintigraphy also suggests that in some cases of transient synovitis there may bae a period of reversible ischaemia of the capital epiphysis, which may have relevance to the pathogenesis of Perthes' disease

We studied, clinically and radiologically, the growth and remodelling of 21 hips after valgus femoral osteotomy with both rotational and sagittal correction for hinge abduction in 21 patients (mean age, 9.7 years) with Perthes’ disease. The exact type of osteotomy performed was based on the pre-operative clinical and radiological assessment and the results of intra-operative dynamic arthrography. The mean IOWA hip score was 66 (34 to 76) before surgery and 92 (80 to 100) at a mean follow-up of 7.1 years (3.0 to 15.0). Radiological measurements revealed favourable remodelling of the femoral head and improved hip joint mechanics. Valgus osteotomy, with both rotational and sagittal correction, can improve symptoms, function and remodelling of the hip in patients with Perthes’ disease

Seventeen patients, with an average age of nine years 11 months, underwent 18 Chiari osteotomies for the treatment of painful subluxation of the hips following Perthes' disease. The average follow-up period was four years three months. The 13 patients reviewed clinically all did well and none complained of pain or instability. The radiographs were examined in all 17 cases. The average centre-edge angle and percentage femoral head cover were definitely improved by the operation. No significant medical displacement of the femoral head was achieved. The clinical success may result from improved femoral head coverage and diminished eccentricity. Chiari's osteotomy is recommended for adolescent patients with painful subluxation of the hip as a consequence of Perthes' disease

Aims. It is well established that there is a strong association between Perthes’ disease and worsening socioeconomic deprivation. It has been suggested that the primary determinant driving this association is exposure to tobacco smoke. This study aimed to examine this hypothesis. Patients and Methods. A hospital case-control study (n = 149/146) examined the association between tobacco smoke exposure and Perthes’ disease, adjusting for area-level socioeconomic deprivation. Tobacco smoke exposure was assessed by parental questionnaire of smoking habits during pregnancy, and by quantitative assay of current exposure using the urinary cotinine-creatinine ratio, which is a widely used and validated measure of tobacco smoke exposure. Results. The odds of Perthes’ disease significantly increased with reported in utero exposure after adjustment for socioeconomic deprivation (maternal smoking odds ratio (OR) 2.06, 95% confidence interval (CI) 1.17 to 3.63; paternal smoking OR 2.09, 95% CI 1.26 to 3.46). The cotinine-creatinine ratio was significantly greater in cases, OR 1.63 (95% CI 1.09 to 2.43), suggesting a greater ‘dose’ of current tobacco exposure. Conclusion. An association exists between tobacco smoke exposure and Perthes’ disease but we remain unable to disentangle the association with socioeconomic deprivation. Cite this article: Bone Joint J 2017;99-B:1102–8

1. Intra-osseous venographs have been obtained in twenty-eight hips affected by Perthes disease and in twenty normal hips after the injection of opaque medium into the femoral neck. 2. In the normal hips the contrast medium drained rapidly into the local veins; none flowed distally into the diaphysis. 3. In the initial and in the fragmentation stages of Perthes' disease some contrast medium always flowed into the diaphysis and the flow into the local veins was greatly reduced. 4. In the restitution stage the venographs approached normal. 5. The implications of these findings are discussed

1. Cancellous bone grafting of the head of the femur in Perthes' disease accelerates reossification and thus shortens the period of treatment. 2. There is no evidence from this series of cases that the final shape of the head is affected for better or for worse by the operation of cancellous chip grafting, by the rate of regeneration of the head after operation or by the stage in the disease process at which the operation is done. 3. No relationship has been found between the shape of the head at the time of operation and its final shape. 4. A larger series of cases is needed to determine the value of bone grafting in Perthes' disease of the hip

The aims of this survey were to establish the familial incidence of Perthes' disease, to note any associated developmental anomalies and to collect information on preceding trauma or synovitis, on the pregnancy and birth, and on various sociological factors. Height and weight measurements were obtained for 217 patients, and comparisons made with those of their parents, unaffected sibs and (local) controls. Results showed an extremely low frequency of Perthes' disease among relatives, with no obvious pattern of inheritance. As genetic factors were not apparent, environmental and sociological causes were sought. The disease occurred particularly in children who were third-born or later in the family, and had older than average parents. Many came from low-income families and one in ten had been a breech birth, shown other malposition or had had a version late in pregnancy. Many children were already undersized at the time of developing Perthes' disease and remained short than average throughout life. Neither their parents nor sibs were shorter than normal, indicating that the patients' short stature was not familial. The child who is going to develop Perthes' disease is already constitutionally and socially at a disadvantage, and during the perinatal period and the first few years of life is perhaps more susceptible to trauma than is a normal child

Perthes' disease involving the whole of the femoral head in 36 children was treated by innominate osteotomy. Radiographs of all cases were reviewed to see the effect of the osteotomy on the shape, the degree of acetabular cover and any subluxation of the diseased femoral head. All femoral heads which were circular before operation remained so, and over half of the previously deformed heads became circular after the osteotomy. The improved acetabular cover provided by the osteotomy resulted in a CE angle of 25 degrees or more in 92% of hips. Possible subluxation of the femoral head was studied by inspecting Shenton's line. If this was intact before operation it remained so; of the 14 which were broken before operation, 11 were restored to normal after osteotomy. We conclude that innominate osteotomy is a worthwhile procedure for Perthes' disease involving the whole of the femoral head

1 . Thirty-four cases of Perthes' disease followed into adult life were reviewed twenty-five to forty years (average thirty years) after diagnosis. 2. Rather more than one-third of the patients developed hips which were good, an equal number were considered fair and about one-quarter were poor. 3. Four out of five patients were fully active and free from pain but only two out of five had hips which were radiologically good. 4. Clinical and/or radiological deterioration had seldom occurred in the last twelve years. 5. A good result in childhood is likely to be maintained with no pain and good function up to the age of forty years and perhaps longer

Valgus extension osteotomy (VGEO) is a salvage procedure for ‘hinge abduction’ in Perthes’ disease. The indications for its use are pain and fixed deformity. Our study shows the clinical results at maturity of VGEO carried out in 48 children (51 hips) and the factors which influence subsequent remodelling of the hip. After a mean follow-up of ten years, total hip replacement has been carried out in four patients and arthrodesis in one. The average Iowa Hip Score in the remainder was 86 (54 to 100). Favourable remodelling of the femoral head was seen in 12 hips. This was associated with three factors at surgery; younger age (p = 0.009), the phase of reossification (p = 0.05) and an open triradiate cartilage (p = 0.0007). Our study has shown that, in the short term, VGEO relieves pain and corrects deformity; as growth proceeds it may produce useful remodelling in this worst affected subgroup of children with Perthes’ disease

We performed a paired study of mature patients with Perthes’ disease to compare the radiological results after treatment between conservatively- and surgically-treated groups. One patient was selected from each group to create the pairs for this study. Each pair was strictly matched for gender, body mass index, age at onset, stage at the first visit, necrotic area and radiological at-risk signs and each was assessed by comparing the values of six radiological measurements. Eighteen pairs (36 hips) fitted the criteria. The radiological measurements which showed a statistically better result in the surgical groups were Mose’s method, the acetabular-head index and leg-length discrepancy. There were no statistical differences in the slope of the acetabular roof and the articulotrochanteric distance. Four hips in the conservative group were in Stulberg class II, five in class III and nine in class IV. In the surgical group, 13 were in Stulberg class II, four in class III and one in class IV. We conclude that surgical treatment improved the sphericity of the femoral head and provided greater acetabular cover, but did not reform the acetabular roof. It was noteworthy that a greater leg-length discrepancy and a smaller articulotrochanteric distance were not seen in the surgical group. Our study suggests that surgical treatment is preferable in patients with severe Perthes’ disease

We evaluated radiological hip remodelling after shelf acetabuloplasty and sought to identify prognostic factors in 25 patients with a mean age of 8.9 years (7.0 to 12.3) who had unilateral Perthes’ disease with reducible subluxation of the hip in the fragmentation stage. At a mean follow-up of 6.7 years (3.2 to 9.0), satisfactory remodelling was observed in 18 hips (72%). The type of labrum in hip abduction, as determined by intra-operative dynamic arthrography, was found to be a statistically significant prognostic factor (p = 0.012). Shelf acetabuloplasty as containment surgery seems to be best indicated for hips in which there is not marked collapse of the epiphysis and in which the extruded epiphyseal segment slips easily underneath the labrum on abduction, without imposing undue pressure on the lateral edge of the acetabulum

It has recently been postulated that thrombophilia may have a role in the aetiology of Perthes’ disease. The published reports, however, remain conflicting. In this study a retrospective analysis of the coagulation parameters was made in 47 patients with Perthes’ disease and the results compared with the clinical data. Five patients with Factor V Leiden mutation were found (10.6%) and surprisingly four of them had a homozygous pattern. These four patients showed the most severe form of the disease, Catterall group IV, with flattening of the entire epiphysis, involvement of the metaphysis, shortening and broadening of the femoral neck, trochanteric overgrowth and developed mushroom-shaped aspherical laterally displaced femoral heads in dysplastic acetabula. We would like to suggest that the homozygous form of Factor V Leiden mutation has some role in the clinical course of Perthes’ disease and particularly its most severe form

We studied the natural history of Perthes’ disease in 62 children in whom the onset of symptoms was in adolescence. Three patterns of disease were noted, namely, late-onset pattern, segmental collapse, or destructive with failure of revascularisation. In the late-onset pattern, the disease followed the sequence of healing seen in younger children, but adequate epiphyseal remodelling did not occur. Consequently, the femoral head was never spherical after revascularisation. With segmental collapse, early and irreversible collapse of part of the epiphysis occurred with gross deformation of the femoral head. The destructive pattern was characterised by a failure of revascularisation and repair of the avascular epiphysis. The radiological outcome was poor in all three patterns. The poorest clinical results were found in the destructive type which was frequently associated with incapacitating pain requiring arthrodesis or excision arthroplasty within three years of onset of the disease

Of 193 children with Perthes' disease at the Texas Scottish Rite Hospital for Cripppled Children, 24 were found to have only minimal changes. The cases were grouped relative to the area of the femoral head involved, with 10 involving the anterior portion, seven the posteromedial, three the lateral, and four the central portion. Almost all hips lost some height as measured by the epiphysial index but all had good results by the Mose criteria irrespective of treatment. The anterior lesion is the same as that described by Catterall as Group 1. The three additional groups have a similar benign natural history but distinct radiographic features. The need for early recognition of these patterns is emphasised if unnecessary treatment is to be avoided. Possible correlations of these lesions with the segmental blood supply of the femoral head are proposed and an hypothesis relating the Catterall classifications to the blood supply is put forward

We have examined the effect of arthrodiastasis on the preservation of the femoral head in older children with Perthes’ disease. We carried out a prospective trial in boys over the age of eight years and girls over seven years at the time of the onset of symptoms. The patients had minimal epiphyseal collapse and were compared with a conventionally treated, consecutive, historical control group. Arthrodiastasis was applied for approximately four months. The primary outcome measure was the extent of epiphyseal collapse at the end of the fragmentation phase. One of the 15 treated hips and nine of the 30 control hips showed a loss of height of 50% or more of the lateral epiphyseal column on the anteroposterior radiographs (Herring grade-C classification). On a Lauenstein view, one of the treated hips and 19 of the control hips showed at least a loss of height of 50% of the anterior epiphyseal column. The complications of arthrodiastasis included pin-site infection in most hips, transient joint stiffness in two, and breakage of a pin in two. The final outcome will be known when all the patients and the control group reach skeletal maturity

1. The progressive radiographic changes in twenty-five patients suffering from Perthes' disease of the hip are described. 2. The prognostic value of lateral views of the hip is emphasised, and the present concepts of pathogenesis in the light of recent observations are discussed

We compared the prognostic value of the Catterall grouping, the Salter-Thompson grading, the arthrographic shape of the femoral head, and the Herring lateral pillar grouping during the fragmentation stage of Perthes’ disease in 73 patients with 81 affected hips. Radiographs were available for study from the onset of the disease until skeletal maturity. We used the Stulberg classification to assess outcome. The Herring grade and arthrographic sphericity proved to be the best predictors of final outcome. Combining these two values further increased the predictive value. All but one patient in Herring group A achieved an excellent outcome. In Herring group B, the age of the child and the sphericity of the femoral head influenced the end result. If the child was less than seven years old at the onset of symptoms the prognosis was invariably good and all spherical hips in group B had a good outcome with Stulberg grades 1 or 2. Moderately and severely deformed hips on arthrography resulted in Stulberg 3 and 4 hips. None of the hips in Herring group C had a normal appearance at maturity and the outcome was not significantly influenced by the age at onset or the arthrographic appearance

Forty-eight images using magnetic resonance imaging (MRI) in 16 hips with Perthes' disease were evaluated over a mean period of two years. MRI depicted exactly the infarcted zone in the femoral head before typical radiological changes were evident. Early determination of the extent of the infarcted bone on MRI benefits those patients who require treatment. Follow-up MRI scans at six-monthly intervals, reflected the chronological stages of the repair process in each group classified according to Catterall

There are differences of opinion about the pathogenesis of Perthes' disease. All are agreed that it is due to ischaemia, but the cause of this and the size and number of infarctions are in dispute. Through the generosity of the contributors six whole femoral heads and core biopsies of five other cases have been studied radiographically and histologically. The findings ranged from an ischaemic arrest of ossification in the capital articular cartilage without infarction to multiple complete infarctions of the epiphysial bone. The ensuing reparative process contributes to the pathology, which is of a range to warrant grading or grouping

1. Eighty-nine cases of Perthes' disease are reviewed. 2. The prognosis varies with the amount of the epiphysis involved. 3. It is possible to assess the amount of epiphysial involvement by a study of the early radiographs. Cases were allocated to four groups on this basis. 4. It is confirmed that both sex and age at the time of diagnosis influence the final prognosis. The reasons for this are discussed. 5. The concept of "the head at risk" is suggested and radiological signs described to diagnose such cases. 6. It is hoped that the classification suggested may in future act as a basis for comparisons of treatment

In a prospective five-year study, 294 episodes of acute transient synovitis of the hip were diagnosed in 275 children. The average annual incidence was 0.2% 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. Perthes' disease was diagnosed from one to five months after the acute attack of synovitis in 10 cases (3.4%). Review of the initial radiographs revealed signs of avascular necrosis in three of the 10 cases, and an increased joint space in five. Only two cases had had completely normal radiographs. The value of routine radiographs taken after three months was minimal. Factors associated with the incidence of Perthes' disease included prolonged time in traction before the range of hip movement became normal, increase in joint space on the initial radiographs and the recurrence of hip symptoms after initial relief

In 40 children with unilateral Perthes' disease, we measured the physeal slope, the angle between the physeal plane and the axis of the femoral shaft, from radiographs taken early in the disease. Thirty-seven of the 40 hips were classified as Catterall grades III and IV. Heat-at-risk signs were present in 23. We found no statistically significant difference in the physeal slope between the involved and normal hips (p = 0.20), those with or without head-at-risk signs (p = 0.96), those with or without lateral epiphyseal subluxation (p = 0.82), and different Catterall (p = 0.56) or lateral pillar (p = 0.67) gradings

Seventy children who had suffered from Perthes' disease were reviewed clinically and radiologically three to eight years from the onset of the condition in order to determine retrospectively the most satisfactory method of assessing the prognosis and the correlation between the clinical and radiological result. In younger children the femoral head was more likely to be spherical at the conclusion of the pathological process but not necessarily of normal proportions nor normally covered by the acetabulum. The prognosis was significantly poorer for girls than for boys. Clinical factors were not an aid to prognosis in the individual cases, but overall there was a close correlation between the clinical and the radiological end-results. The most reliable radiological factors indicating the prognosis were the extent of uncovering of the femoral head, the Catterall grouping, the presence of calcification lateral to the outer limit of the acetabulum and lateral displacement of the femoral head, as measured by comparing the head to tear-drop distances on each side

Premature epiphysial closure is an infrequent complication of Perthes' disease. Twenty-two patients with this condition are reviewed, three of whom were bilaterally affected. The aetiology, radiographic features and effect on function are discussed. The incidence of this complication can be reduced by an awareness of the clinical and radiographic signs which contra-indicate treatment by upper fermoral osteotomy

The pathogenesis of Perthes' disease has been related to increased intra-articular pressure secondary to a joint effusion. The pressure within the hip in different positions was measured in eight children with transient synovitis and four with the synovial stage of Perthes' disease. In the position of comfort for the hip this pressure was always less than the arteriolar blood pressure and in a supine position it did not exceed the systolic blood pressure. However, in extension with medial rotation the intra-articular pressure always became several times the systolic blood pressure. This high pressure was also recorded in the stable lateral position which occurs normally during sleep. It is concluded that in the presence of a synovial effusion in the hip, a position of extension and medial rotation causes an increase in intra-articular pressure which may compromise the blood supply to the capital epiphysis of the femur

1. A rationale of subtrochanteric osteotomy with derotation and varus angulation in the treatment of Perthes' disease is suggested. 2. Three months after operation the child returns to a normal unrestricted life. 3. The anatomical results in twelve such operations with an average follow-up of two years and five months are presented. In five children the results were "very good," in four "good," in one "fair" and in one "bad.". 4. These results seem to compare favourably with those observed after conservative treatment of two, three or more years duration

Fifteen independent observers of three levels of experience (consultant staff, fellows, residents) assessed 40 radiographs of children presenting with Perthes' disease using the Catterall and the Salter-Thompson grading systems. Each observer was supplied with descriptions and illustrations of the classifications and each hip was grouped by both systems by each observer. The results were statistically analysed using 'kappa' statistics. The level of interobserver agreement was higher for the Salter-Thompson system and correlated with the level of experience of the observer. Both systems can give acceptable levels of interobserver agreement, but the Salter-Thompson grouping is simpler and easier to apply in the earlier stages of the disease when treatment must be decided, and has a higher degree of reproducibility amongst more experienced observers

The surgical treatment of Perthes’ disease by femoral or innominate osteotomy is not as effective in those over the age of eight years as it is in the younger child. This has prompted the search for other types of management in those who are older. The preliminary results of the use of a lateral shelf acetabuloplasty for such cases have shown encouraging results at two years. The concern with such an operation is that it might interfere with the growth of the outer aspect of the acetabulum and so prejudice the long-term outcome. We describe a review at maturity of 26 children presenting with early disease after the age of eight years who were treated by lateral shelf acetabuloplasty. The results suggest that the outcome is improved; 22 of 27 hips were rated as Stulberg groups 1 to 3. Poor results occurred in children, particularly girls, presenting with Group-4 disease over the age of 11 years

Upper femoral osteotomy is a recognised treatment for selected patients with Perthes' disease. The results of this procedure were investigated at skeletal maturity in 44 patients (48 hips). The indication for operation was Catterall group II, III, and IV hips with 'head-at-risk' signs. Harris and Iowa scores were calculated clinically, and each hip was assigned radiographically to one of the five Stulberg classes, its initial Catterall grading checked and other relevant indices measured. Results showed excellent clinical function. Shortening was present in 14 hips (29%) and a positive Trendelenburg's sign was seen in 12 (25%). On radiographic assessment 58% of hips were Stulberg class I or II, with a good prognosis. The results of femoral osteotomy were better than those for conservatively treated hips in all age groups except those under five years

A new method of recording the three-dimensional anatomy of the proximal femur from a single anteroposterior radiograph is described. This technique shows that in Perthes' disease the femoral head and neck are in significant anteversion and true varus. This anatomical configuration may be important in the pathogenesis and treatment of this disorder

The results of treating 148 hips in 135 children (aged 7 to 16 at the onset of management) for Perthes' disease are analysed. Cases are classified according to the amount of epiphysial containment and the results assessed according to the degree of preserved sphericity. It is concluded that to obtain satisfactory results in this age group treatment should be prolonged until the restitution of the epiphysis so as to maintain the initially achieved containment throughout the reparative process. Containment should be secured initially as follows: by non-operative treatment, in children aged seven to nine years with contained and also with slightly subluxated epiphyses; by femoral osteotomy, in children aged seven to nine years with severely subluxated epiphyses and also in children aged 10 and more with slightly subluxated epiphyses; by Salter's osteotomy, in children aged 10 years and more with contained epiphyses; by Chiari's osteotomy, in all crushed but smooth epiphyses, and also in children aged 10 and more with severely subluxated epiphyses; and by cheilectomy, in all crushed and saddle-shaped epiphyses, but only during the regenerative stage of the disease

A study was undertaken to assess the degree of inter-observer error when a panel of observers classified the radiographs of patients with early Perthes' disease, using Catterall grouping and "at risk" signs. The anteroposterior and lateral radiographs, taken within three months of diagnosis of Perthes' disease, were available for 69 hips and were shown in turn to 10 observers. The radiological end-results were assessed at least four years from diagnosis. The results showed a poor ability of the observers to delineate Groups 1, 2 and 3, with a more satisfactory performance in Group 4 and when Groups 2 and 3 were combined. Interpretation of "at risk" signs was unsatisfactory except when there was an increase in medial joint space greater than two millimetres. The end-results correlated well with early Catterall grouping and "at risk" signs when these were correctly interpreted

The reliability of the Catterall grouping of Perthes' disease was examined by determining the agreement between pairs of observers using weighted kappa statistics. Anteroposterior and lateral radiographs of 100 hip joints were grouped independently by four experienced observers. There was a low, and in our opinion, unacceptable degree of inter-observer agreement even when Groups 2 and 3 were combined

A prospective survey was carried out on all cases of irritable hip presenting at the Royal Liverpool Children's Hospital over a period of one year. All children had a radioisotope scan of the hips and were then followed for one year by serial radiography. Five of the 50 children seen during the one year had areas of ischaemia in the capital femoral epiphysis demonstrated on the scan. all five developed radiological signs of Perthes' disease within sic months. The remaining 45 had radiographically normal hips at one year

Throughout 1976 orthopaedic surgeons in three regions of England forwarded details of all new patients with Perthes' disease attending outpatient clinics or admitted as inpatients. The incidence in the Mersey region (11.1 per 100 000 children under fifteen years) was twice that in Wessex (5.5) with Trent having an intermediate incidence (7.6). The ratio of male to female incidence varied between the regions as did the age distribution of male cases. These findings point to the importance of environmental factors in the aetiology of the disease, and suggest the need for further epidemiological studies

We have attempted to identify the most important long-term prognostic factors in Perthes' disease by studying 61 patients affected unilaterally. The average age at diagnosis was 7 years 5 months and at follow-up it was 32 years, an average interval of 25 years. The age at diagnosis, age at follow-up, Catterall group, acetabular coverage, femoral head subluxation and the other head-at-risk signs were statistically correlated with Stulberg, Cooperman and Wallensten (1981) radiographic classes and the Iowa hip score. Statistically significant correlations were found between Stulberg class and Iowa hip score; age at diagnosis and Stulberg class; age at follow-up and Iowa hip score; and between lateral subluxation of the femoral head and Iowa hip score. Three age-groups of patients were found to carry different long-term prognoses. Those below five years of age at diagnosis showed a statistically significant correlation between Catterall group and Stulberg Classes I and II. Patients between five and nine years of age at diagnosis showed a significant correlation between Catterall group and Stulberg Classes I, II, III and IV while in patients diagnosed after nine years of age there was no statistical correlation between Catterall group and Stulberg class, all having a poor prognosis and ending up in Stulberg Classes III, IV and V

In order to define the prognostic factors in Perthes’ disease in children older than 12 years, we reviewed 15 patients at the end of growth who were aged 12.1 to 14 years at presentation. The patients with the worst long-term prognosis (Stulberg class V) were compared with the others for age, skeletal maturity and remaining growth (Oxford method), as well as Catterall and Waldenström classifications at presentation. A significant difference (p = 0.001) was found for remaining growth (25% in Stulberg class V and 35% in the others) and also for the results at the end of growth when the remaining growth was over 30%, since this allowed sufficient time for reformation and remodelling of the femoral head

Eighty-four children suffering from Perthes' disease are reviewed. The policy of management for these patients was one by which 55 per cent of the cases had no active treatment and the remainder were treated by operation. Results of the series show an improvement over a previously reported series of untreated controls, particularly where clinical management had been possible throughout the disease process. The importance of early definitive treatment for Group 4 cases is stressed. It is concluded that in the early stages where "head-at-risk" signs are not present, treatment may be conservative. Should these signs develop later the long-term result is not prejudiced if operative treatment is undertaken promptly

The sagging rope sign is the term used to describe the radiographic appearances which sometimes occur after Perthes' disease. It is severe examples of that disease and indicates damage to the growth plate with a marked metaphysial reaction. The same appearance follows severe epiphysitis after forcible reduction of a congenitally dislocated hip, and certain rare epiphysial dysplasias. The origin and significance of the sign are discussed

1. An account is given of a family in which five members in three generations were affected by osteochondritis involving the hips, in three cases bilaterally. 2. One patient showed aseptic osseous necrosis of the epiphyses of the ankles and fingers. 3. The differential diagnosis between Perthes' disease and multiple epiphysial dysplasia is discussed, but it is not certain into which category these patients fall. 4. The assistance of a family history and skeletal survey in diagnosis is illustrated

We reviewed the radiographs of 49 patients with Perthes' disease at the stage of fragmentation and also after the end of skeletal growth to assess the value of the lateral pillar classification of Herring. The average age of the patients at diagnosis was 7 years 6 months and the mean follow-up was 24 years. Ten of the 11 Herring group-A hips showed good reconstruction of the femoral head. There were good results in group-B hips when the patients were less than nine years of age at diagnosis. All 11 group-C patients showed hip deformity at follow-up. The Herring classification provides a valid long-term prognosis in Perthes' disease, although age at diagnosis is also an important prognostic factor. The classification is relatively easy to apply, is reliable, and requires only an anteroposterior radiograph taken during the fragmentation stage of the disease

We have considered the reasons for securing containment of the femoral head in Perthes' disease and have reviewed briefly the methods used. The present investigation describes the outcome in a controlled series of forty-eight hips treated by containment by femoral varus-rotation osteotomy in selected patients. In assessing the results we have emphasised that controls are essential, and for this purpose we have used two comparable groups, one untreated and the other treated by methods other than containment. The same factors were considered in assessment--namely age, duration, group, and the presence or absence of "at risk" signs. The results were graded similarly as good, fair and poor in all groups. We have concluded that containment by femoral osteotomy is the treatment of choice in patients with "at risk" signs provided that severe deformity has not already occurred. There is no evidence that treatment of any kind favourably influences the course of the disorder in the remainder. Although this is predominantly a radiological study some clinical features are discussed

We analysed the short-term outcome after varus osteotomy for Perthes’ disease in 48 older children from south-west India, comparing them with 30 historical controls. The children were between 7 and 12 years of age at the onset of the disease. All had stage-I or stage-II disease, with half or more of the epiphysis involved. The operated children had an open-wedge subtrochanteric varus osteotomy with derotation or extension and a trochanteric epiphyseodesis. Weight-bearing was avoided until late stage III. The non-operated children had been treated symptomatically by conservative methods. At the time of healing, 62.5% of the operated group had spherical femoral heads compared with 20% of those treated non-operatively (p < 0.001). Of the operated children with Catterall group-IV involvement, 48% had good results as against 24% of the non-operated group (p < 0.05). The percentage increase in the radius of the affected femoral head compared with the normal side was significantly lower in children who had operations (14.68 v 25.65; p < 0.001). We have shown that the short-term results of early surgical containment in children over seven years of age are satisfactory

We studied the pattern of proximal femoral growth after severe Perthes' disease (Catterall grade III or IV) by retrospective analysis of serial radiographs in 52 hips (46 patients). Our aim was to determine the relationship between proximal femoral growth abnormalities and metaphyseal cysts, epiphyseal extrusion, physeal narrowing, and extensive epiphyseal necrosis. The average follow-up after treatment was 9.8 years (range 4 to 16 years), and 37 of the hips were followed to skeletal maturity. Slowing of proximal femoral growth was common: symmetrical abnormality was seen in 26 hips and asymmetrical abnormality in nine. However, definite premature closure of the proximal femoral physis was seen in only three hips. Abnormality seemed to be due to altered growth velocity rather than to bar formation in most cases. Metaphyseal cysts, epiphyseal extrusion and physeal narrowing during the active stage of the disease, alone or in combination, were found to be neither sensitive nor specific predictors of the subsequent growth pattern

Twenty-four hips in twenty children affected by Group 1 Perthes' disease have been reviewed to assess the radiographic result after a minimum follow-up of four years. The children were allocated to Group 1 prospectively after examination of the early radiographs and no specific treatment of the affected hip was provided. The radiographic end results assessed by three methods were good even in those cases in which the additional stress of containment splintage of the contralateral hip was applied

Hip arthrography was performed in 19 patients in the initial stage of Perthes' disease. Sphericity and subluxation were measured and it was found that subluxation was independent of the femoral head deformity. We therefore tried to identify the cause of early subluxation: in seven patients a swollen ligamentum teres was thought to be responsible, and was associated with medial pooling of the contrast medium. A swollen ligamentum teres was seen in another seven cases; the other five arthrograms were normal. These findings were further clarified by enhanced CT scans, which confirmed that ligament swelling may be an important cause of early subluxation

The results of a long-term review of 102 hips in eighty-seven patients with Perthes' disease are described, the mean follow-up interval being seventeen years. All had been treated by an extremely rigorous conservative regime in which the patients were kept in hospital for an average period of twenty-six months, during which time they were confined to bed with the legs in wide abduction, first in traction and later in "broomstick" plasters to ensure "containment" of the femoral head. The patients were assessed by the joint clincial and radiological method described by Ratliff (1956). The results were very satisfactory, with only 2 per cent poor results and 10 per cent fair. The remaining 88 per cent were good. The radiological results at the end of treatment have also been compared with control series described by Catterall (1972) and with the osteotomy series of Lloyd-Roberts, Catterall and Salamon (1976). From this it appears that the described regime offers no benefit compared with the natural history in Catterall's Groups I and II, and in Group III the results were only marginally better than those following osteotomy. In Group IV cases, however, where the femoral head was totally involved, the benefit was important, and since these are the cases which carry the worst natural prognosis it is suggested that the use of the method described in such instances must be seriously considered in spite of its social disadvantages. The theoretical implications of the findings are considered, and it is concluded that the benefits of the method cannot be ascribed wholly to the application of the "containment" principle

Perthes' disease is thought to be rare in black children but no figures of incidence have previously been available. A search was therefore made for cases of the disease occurring in the Eastern Cape during the five-year period 1975 to 1979. Of 55 cases found, 38 were in white children, 11 in children of mixed ancestry ("coloured" children) and six in black children. The annual incidence in white children aged 14 years and under was 10.8 per 100 000, in coloured children 1.7 per 100 000, and in black children 0.45 per 100 000. In all races the incidence in the metropolitan area of Port Elizabeth was roughly twice that in the rural part of the region. The reason for the low incidence in coloured and black children is not known but various factors are suggested

We have devised a combined pillar score (CPS) system, based on the lateral pillar (LP) and the posterior pillar (PP) classifications, together with the age at onset of Perthes’ disease, and examined its correlation with prognosis. The correlation coefficient of the Catterall classification, LP, PP, and CPS systems with the Stulberg system was 0.39, 0.52, 0.50, and 0.70, respectively. Overall 21 of the 22 hips (95.4%) with a CPS of 0 to 1 point had a good outcome and 12 of the 13 hips (92.3%) with a CPS of 3 points or more had a fair or poor outcome. None with a CPS of 2 points, had a poor outcome. The study shows that an accurate prediction of the prognosis is not possible with the LP classification alone for patients classified as belonging to group B (LP height 50% to 100% of contralateral height). The CPS system does allow accurate prediction of outcome