Is MRI useful in the postoperative assessment of an open hip reduction in the presence of metal implants?

Developmental dysplasia of the hip (DDH) ranges from mild acetabular dysplasia to complete dislocation and often requires open hip reduction with pelvic and femoral osteotomies using metallic implants when conservative measures fail. Postoperative advanced imaging is essential to confirm hip position. Historically, computed tomography (CT) has been preferred because of metal-induced MRI artifacts, but modern Metal Artifact Reduction Sequences have renewed interest in MRI for this indication. This retrospective, institutional review board–approved study at two pediatric hospitals included patients aged 0–17 years with DDH who underwent open reduction with metallic fixation between November 2017 and September 2025 and had postoperative MRI. Records were screened by CPT codes, and included cases required DDH, metallic implants, and postoperative MRI. Demographics, osteotomy type, implant details, and need for repeat imaging were recorded. A standardized limited protocol with axial and coronal T2 sequences was used. Of 64 eligible cases, 27 hips from 23 patients met criteria. Ages ranged from 10 months to 5 years and were predominantly female. Most underwent combined pelvic and femoral osteotomies; over half had both pelvic and femoral fixation, with a minority having pelvic fixation alone. No patient required repeat advanced imaging for inadequate MRI. These findings suggest that MRI is an effective primary modality for postoperative assessment of hip position in pediatric DDH with metallic implants, while avoiding ionizing radiation and its associated increased lifetime cancer risk compared with CT. Larger, multicenter studies and cost-effectiveness analyses are warranted to refine imaging guidelines in this setting. Level of evidence: IV.