Table 1 Items included for data extraction in selected studies

Study details

Reference, year of publication, geographical location of study, study design, ethical approval, funding, pre-registered protocol

Population details

Number of patients, age, sex, comorbidities, inclusion/exclusion critieria, duration of follow-up, DDH severity or classification, presence of ossific nucleus

Surgical intervention

Anaesthetic used (incl. Nerve blocks/ spinal), single stage or sequential surgery, Surgical approach, anatomical details of the approach, blocks to reduction addressed and how addressed, presence or absence of ligamentum teres, surgical duration, the volume of blood loss, details of additional procedures (e.g. pelvic osteotomy/femoral osteotomy), method of post-operative immobilisation, duration of post-operative immobilisation

Clinical outcomes including hip-specific outcome scores and general quality of life scores

E.g. Modified McKay criteria [33], Children’s Hospital of Oakland Hip Evaluation Scale [34], Pediatric Outcomes Data Collection Instrument (PODCI) [35]

Radiological outcomes including hip and age-specific outcome scores

E.g. rate and severity of AVN (Kalamchi and MacEwen [30] or Bucholz and Ogden classification [31]), acetabular index measured in degrees, Severin Score [32]

Surgical outcomes

Surgical compilation rate, surgical complications according to Clavien-Dindo classification, dislocation rate, secondary surgery