Predictive factors for acetabular labral lesions in osteoarthritis of the hip with radial magnetic resonance imaging – A cross-sectional study

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.

Comparison Between 3-Dimensional Multiple-Echo Recombined Gradient Echo Magnetic Resonance Imaging and Arthroscopic Findings for the Evaluation of Acetabular Labrum Tear

PURPOSE

To evaluate radially reconstructed 3.0-Tesla 3-dimensional multiple-echo recombined gradient echo (MERGE) magnetic resonance imaging (MRI) without arthrography for the assessment of acetabular labrum tears, using arthroscopic evaluation as the reference standard.

METHODS

A total of 71 consecutive hips, including 29 with femoroacetabular impingement, 26 with borderline developmental dysplasia of the hip, and 16 with early-stage osteoarthritis, were evaluated in this retrospective study. MERGE MRI findings were evaluated according to the modified Czerny classification for 3 regions of interest: anterior region, anterolateral region, and lateral region. Cases with severe degeneration that was not concordant with any stage in the original Czerny classification were defined as stage Ⅳ. MERGE MRI findings were compared with arthroscopic findings, and the sensitivity, specificity, positive predictive value, and negative predictive value in terms of the existence of labrum tears were calculated.

RESULTS

MERGE MRI findings revealed labrum tears more frequently in the anterolateral region than in the anterior and lateral regions (P < .01). In cases of femoroacetabular impingement and borderline developmental dysplasia of the hip in particular, labrum tears were more frequently observed on MRI in the anterolateral region than in the lateral region (P < .05). In comparison with MRI findings and arthroscopic findings, our newly defined stage IV in the modified Czerny classification was more frequently observed in cases with a Multicenter Arthroscopy of the Hip Outcomes Research Network (MAHORN) classification of degenerative or complex (P < .01). The average sensitivity and specificity of all regions for the existence of labrum tears were 85% and 56%, respectively. Sensitivity and specificity were 79% and 50%, respectively, in the anterior region; 96% and 50%, respectively, in the anterolateral region; and 70% and 57%, respectively, in the lateral region.

CONCLUSIONS

We validated the diagnostic performance of 3.0-Tesla 3-dimensional MERGE MRI for evaluating acetabular labrum tears and made comparisons with arthroscopic findings. Radially reconstructed MERGE magnetic resonance images showed excellent sensitivity for the diagnosis of labrum tears, particularly in the anterolateral region. The newly defined stage IV was distinctive of early-stage osteoarthritis cases with degeneration and/or complex arthroscopic findings. The noninvasive imaging modality of radially reconstructed MERGE MRI may be an alternative to magnetic resonance arthrography for evaluating labrum tears.

LEVELS OF EVIDENCE

Level Ⅱ, development of diagnostic criteria.

[Labral pathologies of the hip joint]

Magnetic resonance imaging (MRI) of the hip joint is performed for the diagnostics of many clinical pathologies. For clarification of pathologies of the hip joint conventional MRI and MR arthrography are used. The use of MRI either with or without the intravenous administration of contrast material is performed to diagnose bone marrow lesions, necrosis of the femoral head, inflammatory and tumorous lesions affecting the hip joint and its components. After the intra-articular administration of a diluted solution of contrast material, which results in distension of the joint, MR arthrography is performed for the diagnosis of intra-articular pathologies, such as lesions of the labrum acetabulare, chondral lesions and free intra-articular bodies. In recent times, MR arthrography is carried out with continuous traction of the limb to be examined because this leads to a distension of the joint and its components and in this way particularly lesions of the labrum with involvement of cartilage can be visualized even better. This article gives an overview of MRI and the accuracy of detecting lesions of the labrum acetabulare and the influence on the therapeutic approach.

Acetabular labrum of hip joint in osteoarthritis: A qualitative original study and short review of the literature

PURPOSE

Histological architecture of normal acetabular labrum regarding free nerve endings (FNEs) and mechanoreceptors (MRs) has been satisfactorily described in the literature. However, the presence of FNEs and MRs in acetabular labrum of hip joint has been analyzed only once in patients with osteoarthritis (OA). Aim of this article is to report histological distribution pattern of FNEs and MRs in acetabular labrum of patients with severe OA, at the same time conducting a comparison with normal acetabular labrum described in the literature.

METHODS

Seven patients with severe hip OA were enrolled in this study. Patient selection was assisted by the utilization of specific clinical scales delineated by the American College of Rheumatology. After successful total hip arthroplasty, tissue samples of acetabular labra of seven patients were histologically processed and stained with the gold standard chloride method, which was subsequently examined under a compound microscope.

RESULTS

FNEs and MRs constituted the major histological structures. Identified MRs included Pacini corpuscles, Ruffini corpuscles, and Golgi-Mazzoni corpuscles. The presence of FNEs was predominant in the middle part of the acetabular labrum, featuring a remarkable decrease in peripheral parts. In contrast, MRs were detected basically in peripheral parts and less in the middle part.

CONCLUSIONS

Differentiation of the distribution pattern of MRs and FNEs in acetabular labrum of hip joint is remarkable between normal patients and patients with severe OA. The abundance of FNEs in the middle part of the pathologic labrum is mainly responsible for the observed discrimination. A "conversion" of MRs to FNEs may occur during OA progression, modulating therefore this pattern as well as the upcoming clinical manifestations.

A novel rat model of hip pain by intra-articular injection of nerve growth factor-characteristics of sensory innervation and inflammatory arthritis

OBJECTIVES

To determine the direct effects of intra-articular injection of nerve growth factor (NGF) into normal rat hips and the time course of pain-related mediator appearance.

METHODS

Using 36 numbers of 8-week-old male Sprague-Dawley rats, 30 μl of 1% Fluoro-Gold solution (FG) (Sham-operated group; n = 12), 30 μl of 1% FG with 50 μg/ml NGF (NGF50 group; n = 12), and 30 μl of 1% FG with 100 μg/ml NGF (NGF100 group; n = 12) were injected into the left hip joints. Neurons in the dorsal root ganglion (DRG) labeled with FG, and FG and calcitonin gene-related peptide-immunoreactivity (CGRP-IR) were counted. The synovia in the left hip joint was examined histologically.

RESULTS

The NGF50 and NGF100 groups showed evidence of synovitis without cartilage degeneration compared with the Sham-operated group. At 7 days, the proportions of CGRP-IR FG-labeled to total FG-labeled neurons were 12%, 18%, and 36% in the Sham-operated, NGF50, and NGF100 groups, respectively. At 14 days, the proportions were 13%, 22%, and 35% in the Sham-operated, NGF50, and NGF100 groups, respectively. At 7 and 14 days, the NGF50 and NGF100 groups showed a significantly higher proportion of CGRP-IR FG-labeled neurons than the Sham-operated group.

CONCLUSIONS

Intra-articular administration of NGF into the hip joint produces a novel rat model for hip pain.