Persistence of Labral Tears and Resolution of Paralabral Cysts with 2-year MRI analysis after Periacetabular Osteotomy (PAO) for Hip Dysplasia.

Purpose: To evaluate the labrum status and paralabral cysts on preoperative and postoperative magnetic resonance imaging (MRI) in patients with developmental dysplasia of the hip (DDH) who underwent periacetabular osteotomy (PAO).

Methods: A retrospective review was conducted using prospectively collected data from patients who had undergone primary PAO between June 1, 2021 and May 30, 2022. Inclusion criteria were an age range of 16 to 55 years and a minimum follow-up of two years. MRI was utilized to evaluate the preoperative and postoperative conditions of the labrum and the presence of paralabral cysts. Furthermore, the correlations between the presence of paralabral cysts and demographic and radiographic variables were investigated. Additionally, patient-reported outcomes (PROs), minimal clinically important difference (MCID), and complications were reported during the final follow-up evaluation.

Results: A total of 23 patients were included in the final analysis, with an average follow-up of 26.6 ± 3.4 months (range, 24-32 months). All patients diagnosed with symptomatic DDH exhibited labrum tears. MRI scans revealed paralabral cysts in ten out of twenty-four (41.6%) patients, with a significant correlation noted between the presence of cysts and preoperative LCEA (ρ=-0.649; P=0.001), ACEA (ρ=-0.637; P=0.001), Tönnis angle (ρ=0.593; P=0.002) and age (ρ=-0.444; P=0.034). Postoperative MRI scans at one year showed resolution of all paralabral cysts, while labral tears were found to persist. At the end of the follow-up period, most patients improved considerably in PROs compared to preoperative values. The probabilities of achieving the MCID were 91.3% on the HOS-ADL, 78.2% on the HOS-SSS, 91.3% on the mHHS, 73.9% on the iHOT-12, and 69.6% on the VAS pain scale.

Conclusion: All symptomatic patients with DDH had labral tears and a high prevalence of paralabral cysts, which were corrected with reduced acetabular coverage. After PAO surgery, patients experienced notable enhancements in PROs, with resolution of paralabral cysts but persistence of labral tears.