Aims. In this study, we aimed to evaluate incidence trends and potential risk factors associated with Perthes’ disease in Denmark, using publicly available data. Methods. Our population-based case-control study used data from the Danish National Patient Register and Danish Civil Registration System, accessed through the publicly available Danish Biobank Register, to identify 1,924,292 infants born between 1985 and 2016. We estimated age-specific incidence rates for four birth periods of equal duration (1985 to 1992, 1993 to 2000, 2001 to 2008, and 2009 to 2016) and investigated associations with perinatal conditions, congenital malformations, coagulation defects, autism spectrum disorders (ASD), and attention deficit hyperactivity disorders (ADHD). Results. We identified 2,374 (81.6% male) diagnosed with Perthes’ disease aged between two and 12 years, corresponding to an overall incidence of 12.1 per 100,000 live births relative to the year of birth. The incidence declined across all four birth periods, irrespective of sex or age at diagnosis. Several perinatal conditions were associated with higher Perthes’ disease risk. Children with reported birth injuries (vs no reported injuries) exhibited the highest risk (relative risk (RR) 7.48 (95% CI 3.37 to 16.63)) followed by those with versus without coagulation defects (RR 4.77 (95% CI 1.79 to 12.69)). Children diagnosed with syndromic (RR 2.90 (95% CI 2.08 to 4.04)) or non-syndromic major congenital malformations (RR 1.86 (95% CI 1.55 to 2.23)) (vs those with no malformation diagnosis) were also associated with higher Perthes’ disease risk. The development of Perthes’ disease was positively associated with several ASD and ADHD diagnoses. However, once adjusting for the sex of the child and period of birth, the associations with ASD and ADHD were no longer significant. Conclusion. Using publicly available data, we observed a declining incidence of Perthes’ disease in Denmark over a 32-year study period. Our findings also confirm positive associations between Perthes’ disease and various perinatal conditions, coagulation defects, and congenital malformations, highlighting potential aetiological pathways for further investigation. Cite this article: Bone Joint J 2025;107-B(2):268–276

The August 2024 Children’s orthopaedics Roundup³⁶⁰ looks at: Antibiotic prophylaxis and infection rates in paediatric supracondylar humerus fractures; Clinical consensus recommendations for the non-surgical treatment of children with Perthes’ disease in the UK; Health-related quality of life in idiopathic toe walkers: a multicentre prospective cross-sectional study; Children with spinal dysraphism: a systematic review of reported outcomes; No delay in age of crawling, standing, or walking with Pavlik harness treatment: a prospective cohort study; No value found with routine early postoperative radiographs after implant removal in paediatric patients; What do we know about the natural history of spastic hip dysplasia and pain in total-involvement cerebral palsy?; Evaluating the efficacy and safety of preoperative gallows traction for hip open reduction in infants

Aims

The reduction in mobility due to hip diseases in children is likely to affect their physical activity (PA) levels. Physical inactivity negatively influences quality of life and health. Our aim was to objectively measure PA in children with hip disease, and correlate it with the Patient-Reported Outcomes Measurement Information System (PROMIS) Mobility Score.

The August 2014 Children’s orthopaedics Roundup³⁶⁰ looks at: Conservative treatment still OK in paediatric clavicular fractures; Femoral anteversion not the usual suspect in patellar inversion; Shoulder dislocation best treated with an operation; Perthes’ disease results in poorer quality of adult life; Physiotherapy little benefit in supracondylar fractures; Congenital vertical talus addressed at the midtarsal joint; Single-sitting DDH surgery worth the effort; and cubitus valgus associated with simple elbow dislocation