Serial Magnetic Resonance Imaging Analysis Reveals Acetabular Labral Volume Decreases After Labral Reconstruction and Returns to Native Size.

Abstract

Purpose: To investigate the consecutive changes in labral size and signal-to-noise ratio (SNR) on magnetic resonance imaging after labral reconstruction and to determine factors including patient characteristics and graft diameter associated with postoperative labral size and their effect on clinical outcomes.

Methods: Data between October 2021 and December 2023 were reviewed. Patients diagnosed with femoroacetabular impingement syndrome and who underwent hip arthroscopy for labral reconstruction (irreparable nondiminutive labrum) were included. Exclusion criteria were incomplete magnetic resonance imaging data and concomitant hip conditions. The cross-sectional area of the labral size at 11:30, 1:30, and 3:00 o'clock positions and SNR at 11:30 position was measured on magnetic resonance imaging at preoperative, immediate postoperative, 3/6/12-month postoperative timepoint. Visual analog pain scale (VAS), modified Harris Hip Score, and 12-component International Hip Outcome Tool were collected preoperatively and at follow-up. The achievement of a minimal clinically important difference was calculated.

Results: Twenty patients were included. The labral size significantly decreased at postoperative 3 months (11:30, P = .007; 1:30, P < .001; 3:00, P = .018), 6 months (11:30, P < .001; 1:30, P < .001; 3:00, P = .018), and 12 months (11:30, P < .001; 1:30, P < .001; 3:00, P = .012) compared to the immediate postoperative value and returned to its preoperative native size at 6 months (3:00, P = .310) and 12 months (11:30, P = .778, 1:30, P = .500). The SNR presented a significant increase at all postoperative timepoints (3 months, P = .004; 6 months, P = .001; and 12 months, P < .001) compared with the immediate postoperative value and returned to its preoperative level at 6 months (P = .215) and 12 months (P = .370). Graft diameter was positively correlated with 12-month postoperative labral size at both 11:30 and 1:30 positions. Graft diameter was positively associated with VAS improvement. A total of 85%, 90%, and 80% of patients achieved a minimal clinically important difference of VAS, modified Harris Hip Score, and 12-component International Hip Outcome Tool, respectively. The cutoff value of graft diameter predicting the achievement of a minimal clinically important difference of VAS was 5.5 mm.

Conclusions: In patients with a nondiminutive native labrum preoperatively, the reconstructed labral size gradually decreased and returned to its preoperative native size by 6 to 12 months. The SNR of reconstructed labrum gradually increased and returned to its preoperative level by 6 to 12 months. Larger graft diameter was associated with greater 12-month postoperative labral size and reduction of pain.

Level of evidence: Level IV, retrospective case series.