Although older children and high dislocations may be more likely to require a femoral shortening osteotomy, the ultimate decision about whether or not to shorten a given femur should depend on the ease of femoral head reduction in that specific patient. Adding a femoral shortening procedure increases operating time and blood loss, adds a second incision, and necessitates future hardware removal. In addition, an unnecessary femoral shortening osteotomy could overly decrease the soft tissue tension around the joint, putting the hip at risk for redislocation. This study was designed to explore an algorithm based on strict age and radiographic criteria that identify those without the need of femoral osteotomy.

Developmental dislocation of the hip (DDH) is a common disease in children, and its incidence in China is about 9 ‰.There are many different methods in the treatment of DDH. Although older children and high dislocations may be more likely to require a femoral shortening osteotomy, the ultimate decision about whether or not to shorten a given femur should depend on the ease of femoral head reduction in that specific patient. Adding a femoral shortening procedure increases operating time and blood loss, adds a second incision, and necessitates future hardware removal. In addition, an unnecessary femoral shortening osteotomy could overly decrease the soft tissue tension around the joint, putting the hip at risk for redislocation. This study was designed to explore an algorithm based on strict age and radiographic criteria that identify those without the need of femoral osteotomy. From the investigators'clinical experiences and the published papers, younger patients (<24 month of age) and low dislocations (Tonnis level I or II) were more likely to avoid a femoral shortening osteotomy.

Inclusion Criteria:

1. Unilateral DDH,age 18-24month.
2. Tonnis degree I or II.
3. Not receive any open treatment.

Exclusion Criteria:

1. Teratologic hip dislocations,
2. Patients with mental, neurological disorders (such as hypoxic-ischemic encephalopathy, epilepsy and dementia) or significant barriers to growth, cerebral palsy, multiple joint contractures disease, dysfunction of liver and kidney , blood disorders, immune deficiency disease and ECG abnormalities.
3. Any children with prior hip surgery were excluded from the series.
4. Parents refused further treatment.

The single-center data will be published in the form of case-control study.