Risk factors for developmental hip dysplasia in a single clinical center

Recently, screening for DDH in young children has become widely accepted4.11. Early treatment of DDH might give better results compared to late treatment. Considering that China is a developing country, a new screening system, adapted to our region, should be put in place. There are currently three types of screening systems, which are: clinical examination alone, general ultrasound screening, and a combination of ultrasound and risk factor screening.4. The American Academy of Pediatrics recommends that ultrasound be used to evaluate female breech infants and those with a family history of DDH in the United States.12. In the UK, a family history of DDH, breech position, multiple births and clinical hip instability were the indicators of the US examination for the diagnosis of DDH. In this study, we also attempted to adopt the methods used in the United States and the United Kingdom.13. There are two limitations associated with using US-only screening in our region. Although the American technique is affordable, costing around US$20, the procedure must be performed by an experienced sonographer. The second major reason for not adopting full screening was that American machines were not readily available in some rural areas of our region. In this study, we successfully established our own suitable screening method which combined risk factor assessment and American examination, which effectively increases the screening efficiency and decreases the cost of DDH in our region.

Several risk factors are associated with DDH8.14. Some studies have reported a strong correlation between DDH and a family history of DDH, breech presentation, swaddling, and congenital foot deformity8,11,15,16. In this study, we sought to confirm the correlation between DDH and risk factors for DDH in our region. We have included other risk factors that may also be important, such as diabetes, hyperthyroidism, hypothyroidism, hepatitis B, pulmonary tuberculosis and pregnancy-induced hypertension, during pregnancy. In our country, vaccinations are scheduled at the age of 1, 3, 4 and 5 months. Doctors are advised to examine the hip during these visits. We also analyzed number of pregnancies, number of weeks of gestation, gestational age, oligohydramnios, mode of delivery (cesarean section or vaginal delivery), breech presentation, birth weight, deformity of the foot, congenital torticollis, swaddling, family history (minimal in the control group), and pregnancy-related diseases (diabetes and hyperthyroidism). The results showed that only female sex, vaginal delivery, breech delivery, foot deformity, oligohydramnios were risk factors for DDH in our region, which contradicts the results of previous studies.6.11.

There is no consensus on risk factors for congenital muscular torticollis. Breech presentation is considered one of the risk factors for torticollis. This may lead to misleading conclusions regarding congenital muscular torticollis if breech presentation is included in screening. In our study, 15.20% (31/204) and 0.99% (4/404) of patients in the case and control groups, respectively, had breech presentation, showing a significant difference (p

Some studies have reported that foot deformities, including congenital equinus varus clubfoot, may be correlated with DDH17. In this study, 13 children with DDH and only 2 children in the control group had foot deformity, and the difference was significant (p

Breech presentation is considered a risk factor not only for congenital muscular torticollis but also for DDH. Many studies have reported a strong correlation between breech presentation and DDH15.18. Lambek et al.19 demonstrated that cephalic presentation is associated with a reduced risk of DDH compared to breech presentation, and that girls are at higher risk. In our study, 31 of 204 infants were born by breech delivery (p 18 also reported that infants born breech by caesarean section had a significantly lower risk of DDH; our study showed the same results as the others. However, the DDH group showed a lower incidence of first birth, and first birth was not significantly correlated with DDH. There was a government policy in China in 2016 that allowed families to have a second child. Consequently, there were many second children during the study period. Further studies involving more patients should be conducted to assess this.

Factors related to limited fetal mobility, such as oligohydramnios and high birth weight, had an increased risk of DDH20.21. In our study, we found that oligohydramnios posed an increased risk. In the DDH group, 13 of 204 patients had oligohydramnios, while in the control group, 3 of 408 infants had oligohydramnios (p

The swaddling method is also considered a risk factor. Most surgeons suggest that parents should not tightly swaddle infants. This was confirmed by Yamamuro et al.22, which launched a national campaign in 1975 to prevent prolonged extension of hips and knees in infants during the early postnatal period; as a result of this campaign, the incidence of DDH decreased significantly. In our study, no significant difference was found in the use of the swaddling method between the case and control groups. This is because parents have not adopted the habit of holding infants’ hips in extended extension, as in the swaddling method. The temperature in our region is not low; therefore tight swaddling is not necessary23.

Indications for early treatment of DDH remain controversial24. Some researchers monitor children with type IIa hips and treat those with IIc or D hips, while others follow patients with type IIc and D hips and treat patients with type III and IV hips.25. In our study, 77 patients were diagnosed with type IIc hips; however, retrospective analysis of clinical data showed that only 61.0% (47/77) of patients were treated with the Pavlik sling, and the remaining 30 patients were uncooperative during follow-up or were lost to follow-up. seen ; thus, these 30 patients were excluded from our study. There is a lot of controversy regarding patients who require treatment26. Peled et al.27 reported that the incidence of suspected DDH requiring treatment is

There are some limitations to this study. First, it was a retrospective study. A prospective study should be conducted to validate our methods and our results. Second, the follow-up period was only > 12 months; a longer follow-up period is therefore necessary, in particular for cases of DDH of the acetabular dysplasia type. Third, our sample size was small; future studies should recruit a larger cohort of patients. Fourth, not all of the patients included in this study were neonates; this is a concern because early treatment can produce good results. Fifth, treatment outcomes were not evaluated; this should be a priority in future studies. Sixth, the control group did not include healthy individuals; therefore, our method may also introduce bias. Finally, patients with DDH in this study may have included some patients with syndromic entities, inherited bone or connective tissue disorders, or other related disease, which may also have introduced bias.