Radiographic analysis to determine the treatment outcome in developmental dysplasia of the hip.

: The purpose of this retrospective study was to determine whether pretreatment radiographic findings of patients less than 6 months old with developmental dysplasia of the hip can predict treatment outcome. Medical records and radiographs were reviewed in a cohort of 35 patients (44 hips) less than 6 months old with a diagnosis of hip dislocation at one institution. Using pretreatment anteroposterior radiographs, we measured the superior gap (distance between the proximal metaphysis to Hilgenreiner's line) and the medial gap (distance between the femoral calcar and the lateral pelvic wall at that level) and analyzed these data along with the type of splint used (Pavlik harness verses other abduction orthosis). Medical records and radiographs from an aged-matched cohort of 20 patients (23 hips) treated at a second institution were analyzed by using the same clinical and radiographic criteria of hip dislocation. Of the 44 dislocated hips, 29 failed with a trial of splintage (66%). Of the 23 dislocated hips from the second institution, 16 failed a trial of splintage (70%). Statistical analysis evaluating the age of the patient, medial and superior gaps, and harness type revealed that an abnormal superior and medial gap consistently predicted success or failure of splintage. We concluded that infants with pretreatment radiographs revealing a superior gap equal to or less than 3 mm, or a medial gap equal to or greater than 10 mm should not be treated with an initial trial of splintage because failure is likely.