Incidence of risk factors in developmental dysplasia of the hip: a retrospective study on 18,954 cases.

Background: DDH is 1 of the most important causes of childhood disability. A diagnosis of instability can be made in the neonatal period via the Ortolani and Barlow manoeuvres. However, clinical examination, although highly specific, has poor sensitivity as compared to ultrasound. There is controversy between the necessity of universal screening for dysplasia of all newborns or selective screening reserved for those with clinical signs of instability or known risk factors of DDH.

Aim: To analyse the risk factors of congenital hip dysplasia in a consecutive case series of children referred for diagnosis and treatment of DDH.

Materials and methods: This was a cross-sectional study on infants consecutively examined between January 2000 and December 2019 at the Marino Ortolani Centre in Ferrara, Italy. The first 3 types on Graf's classification were considered physiological (1A, 1B, 2A+), while the last 6 pathological (2A-, 2B, 2C, 2D, 3, 4).

Results: 18,954 infants met the inclusion criteria and were therefore considered eligible for the study. Of these 18,954 infants, 56% (n = 10,629) were females and 44% (n = 8325) were males. According to Graf classification, 34.9% (n = 6621) were 1A, 52.7% (n = 9999) were 1B, 4.0% (n = 753) were 2A+, 2.5% (n = 478) were 2A-, 1.5% (n = 284) were 2B, 1% (n = 196) were 2C, 1.3% (n = 243) were 2D, 1% (n = 193) were 3 and 1.0% (n = 187) were 4. The most significant risk factor was the female gender (OR 5.36; 95% CI, 4.63-6.20) followed by a family history (OR 2.35; 95% CI, 2.08-2.65), then skeletal pathologies (OR 2.04; 95% CI, 1.21-3.42), oligohydramnios (OR 1.75; 95% CI, 1.44-2.13), and finally breech presentation (OR 1.42: 95% CI, 1.27-1.60).

Conclusions: Based on our data, family history, musculoskeletal disease, oligohydramnios and breech presentation are the main risk factors for DDH development, as is the female sex.