A modified non-contrast MRI in the preoperative examination of periacetabular osteotomy at 3.0T.

PURPOSE

To investigate whether the modified hip non-contrast magnetic resonance imaging (MRI) can replace the direct MRI hip arthrography (d-MRA) at 3.0T in developmental dysplasia of the hip (DDH) patients undergoing periacetabular osteotomy (PAO) preoperative examination, and also to assess the difference between these two methods.

MATERIALS AND METHODS

This retrospective study involved 35 patients (38 hips) with DDH who underwent periacetabular osteotomy, age 9-41 years old (mean age 25), 4 males (4 hips) and 34 females (34 hips). Each patient underwent both d-MRA and modified 3.0T non-contrast MRI examination of the hip joint. All patients underwent hip-preserving PAO surgery subsequently. Statistical analyses were performed to compare the joint injury examined by the two imaging methods.

RESULTS

The modified non-contrast MRI detected the labral injury with a sensitivity of 94%, a specificity of 75%, an accuracy of 92%, and a positive predictive value of 97%. Among the 38 hips, 10 hips had labral varus (i.e., inward deviation or angulation of the acetabular labrum) with an incidence rate of 26% (10/38), 9 hips had acetabular cysts (i.e., the fluid-filled sacs that develop in or around the acetabulum, the socket of the hip joint) with an incidence rate of 23% (9/38). One patient had both the labral cyst and acetabular cartilage injury, and two patients had labral cyst only (overall incidence rate of labral cyst 7% (3/38)). The results were comparable to those of d-MRA in the examination of cartilage injury, labral varus, acetabular cyst, and labral cyst.

CONCLUSION

For preoperative hip-preserving surgery in DDH patients, the modified non-contrast MRI performed similarly to the d-MRA at 3.0T in diagnostic capabilities. The labral injury mostly occurs in the anterior upper quadrant.