Utility of radial reformation of three-dimensional fat-suppressed multi-echo gradient-recalled-echo images for the evaluation of acetabular labral injuries and femoroacetabular impingement

Radial Planes in Hip Magnetic Resonance Imaging: Techniques, Applications, and Perspectives

The hip cartilage and labrum, as the main targets of femoroacetabular impingement, sports-related or traumatic damage, as well as congenital and developmental abnormalities, have attracted increasing attention with the development of magnetic resonance imaging (MRI) and hip arthroscopy. MRI is a commonly used imaging modality to noninvasively visualize the hip cartilage and labral lesions. However, conventional orthogonal MRI planes encounter unique challenges given the ball-and-socket configuration of the hip joint, its anatomically abducted and anteverted orientation, and the thin, closely apposed cartilage enveloping the femoral head and acetabulum. Advancements in hip MRI's radial plane, which is acquired through the center of the hip joint, offer a solution. This technology provides true cross-sectional images of the cartilage and labrum perpendicular to the curvature of the joint, thereby mitigating the partial-volume-averaging effects. The integration of 3.0-Tesla high field strength and three-dimensional (3D) acquisition techniques further enhances the capabilities of the radial plane. This combination yields a high signal-to-noise ratio, high spatial resolution, high contrast between intraarticular structures, while minimizing partial-volume-averaging effects. Such improvements potentially facilitate the comprehensive detection of even minor chondral and labral lesions. The capability for multiplanar reconstruction from a single 3D volumetric acquisition further strengthens the usefulness of the radial plane by aiding in precise localization of hip cartilage and labral lesions, in line with hip arthroscopy findings. These advancements have the potential to standardize MRI evaluations and radiographic reporting systems for hip cartilage and labrum, offering precise guidance for hip arthroscopy. This article presents a comprehensive review of radial plane technology applied to the hip MRI, and discusses the morphological assessment and localization of hip cartilage and labral lesions utilizing this advanced imaging technique. EVIDENCE LEVEL: 5 TECHNICAL EFFICACY: Stage 2.

Acetabular Labral Repair and Selective Labral Debridement Show No Significant Difference in Clinical Outcomes at a Minimum 2-Year Follow-Up

PURPOSE

To compare the outcomes of arthroscopic labral repair using looped type suture with a matched-pair selective labral debridement with a minimum 2-years follow-up.

METHODS

We identified 378 patients undergoing primary arthroscopic labral repair using loop-suture and selective labral debridement from January 2, 2018, to December 28, 2020. The labral repair group was matched 1:1 to a selective labral debridement control group by age, sex, body mass index, follow-up period, lateral center-edge angle, Tönnis grade, and preoperative joint space. Before surgery, 3-Tesla radial magnetic resonance imaging with a 3-dimensional double-echo steady-state sequence was obtained following failed nonoperative treatment lasting more than 3 months. Follow-up imaging was conducted at a minimum of 2 years. In both groups, the ratio of positive slices in which a disrupted chondrolabral junction was observed between the 2 o'clock and 11 o'clock positions was measured. Patient-reported outcome scores included the Harris Hip Score, visual analog score, Hip Outcome Score Activities of Daily Living Subscale, and Hip Outcome Score of Sport-Specific Subscale.

RESULTS

In total, 76 patients of the repair group were matched to 76 controls with a minimum 2-years follow-up (repair vs control: 2.6 ± 0.4 vs 2.6 ± 0.4 years, P = .775). The repair group experienced a 2-fold improvement (0.6 ± 0.1 to 0.3 ± 0.1, P＜.001). Although the selective debridement group experienced a 3-fold improvement (0.3 ± 0.1 to 0.1 ± 0.1, P＜.001). Significant improvement of the patient-reported outcome was shown in both groups at final follow-up without significant difference between the 2 groups.

CONCLUSIONS

The mid-term clinical outcomes are comparable between the labral repair using looped type suture and selective labral debridement group. Although a gap between the labrum and articular cartilage may appear in 3-dimensional double-echo steady-state magnetic resonance imaging results after labral repair, it does not correspond with clinical outcomes.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Microfracture of Acetabular Rim After Segmental Labral Resection to Restore the Morphology and Function of Labrum: A Retrospective Study of More than 2 Years Follow-up

Objective

To report on the clinical outcome of patients undergoing combined arthroscopic treatment of labral resection and microfracture at the rim of acetabulum at a minimum 2‐year follow‐up.

Methods

The retrospective study included 38 patients undergoing hip arthroscopy for irreparable labral injury from 24 February 2014 to 26 February 2018. Thirteen patients were excluded owing to patient refusal of participation and concomitant diseases like synovial chondromatosis and dysplasia hip. The study group consisted of patients undergoing combined arthroscopic labral resection and microfracture at the rim of acetabulum (MICRO Group: 20 patients), arthroscopic labral resection alone (RESEC Group: five patients). Postoperative three‐dimensional (3D) double‐echo steady‐state (DESS) sequence with radial imaging at 3 Tesla were obtained and fluoroscopic image of the involved hip under distraction were used to observe the restoration of vacuum effect. Patient‐reported outcome scores (PROs) including the Harris Hip Score (HHS), Visual Analogue Score (VAS), Hip Outcome Score Activities of Daily Living Subscale (HOS‐ADL), Hip Outcome Score Sport‐Specific Subscale (HOS‐SSS) were collected and compared between two groups.

Results

All patients were followed up for at least 6 months. The follow‐up time of RESEC group is longer than MICRO group (46.6 months vs 23.9 months, P < 0.05). The 3D DESS imaging demonstrated intermediate signal intensity at the relative area where the labrum resected followed by microfracture at the acetabular rim in MICRO group. Meanwhile, regrowth of labrum‐like tissue was not observed in MRI imaging of the RESEC group. Furthermore, vacuum effect was more apparent in MICRO group compared with RESEC group. All PROs in both groups showed a statistically significant improvement at follow‐up compared with preoperative levels. RESEC group: HHS (73.0 vs 93.8, P < 0.05); HOS‐ADL (51.5 vs 89.1, P < 0.05); HOS‐SSS (47.8 vs 88.3, P < 0.05); VAS (6.4 vs 2.0, P < 0.05). MICRO group: HHS (70.5 vs 91.5, P < 0.05); HOS‐ADL (52.4 vs 87.0, P < 0.05); HOS‐SSS (48.1 vs 86.5, P < 0.05); VAS (6.3 vs 1.6, P < 0.05). One patient of MICRO group had transient neurapraxias of the pudendal nerve that resolved completely by 3 months. There showed no statistically significant difference between groups regarding the preoperative and postoperative PROs.

Conclusion

Compared to labral resection, combined arthroscopic labral resection and microfracture at the rim of acetabulum is able to fulfill the labral defect area with the potential to restore the seal effect of labrum as an effective and safe option for irreparable segmental labral tears.