Developmental dysplasia of the hip (DDH), which is a common congenital hip disease with an incidence between 0.16 % and 2.85 %,1 is associated with an increased risk of secondary osteoarthritis (OA) and premature total hip arthroplasty (THA). This disorder is responsible for 9 % of all THAs and nearly one-third of those in patients 60 years old and younger.2 Although patients with DDH tend to be younger and more tolerant of THA than patients with primary OA, various anatomical abnormalities in DDH, such as small native acetabula, insufficient bone stock, and dislocation of the femoral head, may increase their surgical complexity and influence postoperative outcomes.3

Limited studies have reported short-term complications following THA in patients with DDH.4,5 Seo et al. studied 336 patients with DDH in a single center and found that DDH patients had a low incidence of dislocation and all-cause readmission; however, this study did not establish a control group of patients who underwent THA without DDH.4 In a retrospective study of 603 DDH patients, Siddiqi et al. found that there was no significant difference regarding in-hospital complications between the DDH and OA groups.5 However, only five patients in the OA group and four patients in the DDH group had in-hospital complications in that study, which limits the validity and generalizability of these results. Therefore, a well-designed study with a large sample size is needed to identify whether DDH increases the incidence of complications following THA. DDH occurs at a rate of 1.52 % in Chinese adults,6 which is nearly five to ten times higher than that in Western countries.2 According to Chinese national population statistics, there are an estimated 16.05 million Chinese adults with DDH.7 Studies based on numerous cases will provide important references for the clinical management of patients with DDH.

Moreover, DDH and OA patients have very different patient characteristics, which may lead to different readmission causes and management strategies. Recently, there has been growing interest in defining readmissions that occur from surgical causes as a more accurate reflection of preventability and hospital quality.8 However, the relationship between DDH and surgical readmission is still unclear. Clarifying the prognosis and readmission patterns of patients with DDH would provide an important reference for clinical management and policy formulation for this population.

Using the Chinese national database (i.e., Hospital Quality Monitoring System [HQMS]), we conducted this study to determine in-hospital complications, 90-day all-cause, and surgical readmission of THA in patients with DDH and primary OA.