MR imaging of normal hip anatomy

Osteoarthritis of the hip: is radiography still needed?

Diagnosis of hip osteoarthritis (OA) is based on clinical arguments, and medical imaging is obtained to confirm the diagnosis and rule out other possible sources of pain. Conventional radiographs are recommended as the first line imaging modality to investigate chronic hip pain. They should be obtained in a rigorous technique that includes an antero-posterior (AP) radiograph of the pelvis. The choice of the appropriate lateral view depends on the clinical indication, Lequesne's false profile being valuable in the assessment of OA. Magnetic resonance imaging (MRI) is more sensitive to detect joint effusion/synovitis, cartilage, labral, and bone marrow lesions. However, structural joint changes are frequent in asymptomatic population and neither radiographs nor MRI have shown a good correlation with pain and functional impairment. MRI seems to be more suitable than radiographs as a biomarker for clinical trials addressing early OA. The absence of a validated MR biomarker of early OA, together with issues related to machine availability and MRI protocol repeatability, prevent the widespread use of MRI in clinical trials.

Acupuncture Treatment for Hip Pain: A Systematic Review and Meta-Analysis

Acupuncture treatment (AT) is an effective treatment for pain relief; however, there are few systematic reviews that have reported on the effectiveness of AT for hip pain. This systematic review aimed to evaluate the efficacy and safety of AT of hip pain. We searched eight databases for randomised controlled trials (RCTs) evaluating the effect of AT on hip pain until August 2022. Twelve RCTs (806 patients) were included: two reported a significant effect of AT compared with that of conventional medicine (CM) alone for hip pain; two reported significant effects of AT + CM compared with that of CM alone in terms of Visual Analogue Scale (VAS); two reported a significant effect of AT + CM compared with that of Sham AT + CM in terms of anaesthetic dosage; two reported a significant effect of AT + CM compared with that of Sham AT + CM in terms of the side effects associated with analgesic use; one study reported a significant effect of AT compared to that of no-treatment. No serious adverse events were reported. Our findings demonstrate the potential of AT in managing hip pain. Given the low quality and small sample sizes of the studies, the evidence supporting AT for hip pain management was weak. Further clinical trials and systematic reviews are required. The protocol of the current study was registered in the PROSPERO International prospective register of systematic reviews (CRD42017079586).

Particularities on Anatomy and Normal Postsurgical Appearances of the Hip

Detailed knowledge of anatomy helps to understand pathologic processes. This article focuses on the anatomy and functionality of the hip, with emphasis on recently studied concepts and anatomic features that have an association with the development of symptoms. The most common anatomic variants posing a challenge for diagnosis and other common findings in asymptomatic patients are reviewed. Good understanding of the different surgical procedures helps in providing as much information as possible to guarantee a favorable outcome, improving prognosis. We review what are the commonly expected postsurgical appearances and the most common postsurgical complications.

Age dependent prevalence of the supraacetabular fossa in children, adolescents and young adults

OBJECTIVES

The supraacetabular fossa (SAF) is an anatomical variant of the acetabular roof which may mimic a cartilage defect. Two different subtypes have been described: type 1 fluid-filled and type 2 cartilage-filled. The adult prevalence of SAF was reported between 10.5 and 12.6%. We aimed to determine SAF prevalence in a pediatric and young adult population and examine the potential remodeling of the subtypes over time.

METHODS

A retrospective search of the institutional database for hip MRI of participants aged 4-25 years was carried out between 2010 and 2020. A total of 401 eligible MRIs of 323 participants were analyzed by two readers. The documented features were: existence of SAF, definition of subtype and measurements of the SAF in three dimensions. Logistic regression models were calculated to estimate the influence of age on the presence of SAF.

RESULTS

Out of 323, 115 (35,6%) participants demonstrated a supraacetabular fossa. 63 (19.5%) participants presented subtype 1 and 51 (15.8%) type 2; one participant had both. The predicted probability for SAF increases until the age of 14, beyond 14 years, the combined predicted probability for both subtypes decreased again. In contrast to SAF type 1, SAF type 2 was more prevalent with older age. The size of the SAF decreased with aging.

CONCLUSION

The supraacetabular fossa is most frequent in adolescents. With higher age, the prevalence and the size of the SAF decreased. This data supports the theory that the SAF is a developmental variant.

The Everted Acetabular Labrum: Patho-anatomy, Magnetic Resonance Imaging and Arthroscopic Findings of a Native Variant

PURPOSE

The purpose of this study was to introduce a native labral variant, the everted acetabular labrum, and to describe the patho-anatomy, magnetic resonance imaging and magnetic resonance arthrogram (MRI/MRA) characteristics and the arthroscopic findings in this condition.

METHODS

All primary hip arthroscopy procedures performed by the senior author between June 2013 and January 2020 were reviewed retrospectively. An everted acetabular labrum was identified as a segment of labrum that lacked apposition to the femoral head with the hip off traction. All everted labra were treated with labral advancement and repair with or without augmentation or reconstruction. The labrum-to-femoral head distance was measured in 3T MRI/MRA at the 1-2 o'clock position. A random selection of 38 hips without an everted labrum served as controls to compare radiographic parameters.

RESULTS

A total of 68 hips were identified as having an everted labrum during the study period (mean age, 29.1 years), and 55 hips had advanced imaging available for review. MRI/MRA scans revealed the everted labrum to have a triangular shape in 17 hips (31%) and a blunted/round shape in 38 hips (69%), which differed significantly from controls (triangular 25/38 [66%], blunted 13/38 [34%], P < 0.001). The average labrum-to-femoral head distance was 1.4 mm for everted labra versus 0.0 mm for controls (P < 0.0001) and the mean labral lengths and widths were significantly shorter than those of controls (both P < 0.01). Of the hips, 8 underwent labral reconstruction or augmentation, and 61 underwent labral advancement/repair.

CONCLUSION

The everted acetabular labrum is a native variant that is identifiable during hip arthroscopy by assessing the labral seal off traction. Preoperative MRI/MRA findings can be highly predictive of an everted labrum. Surgical treatment includes labral advancement and repair or reconstruction to restore contact between the labrum and the femoral head.

LEVEL OF EVIDENCE

III, retrospective comparative study.

Hip Pain: Imaging of Intra-articular and Extra-articular Causes

Hip pain is a common and complex clinical entity. The causes of hip injuries in athletes are many and diverse, requiring efficient, accurate diagnosis for proper management. Imaging is an important step in the clinical evaluation of hip pain, and familiarity with multiple imaging modalities as well as characteristic imaging findings is a helpful tool for sports medicine clinicians. This article discusses imaging recommendations and gives imaging examples of common causes of intra-articular and extra-articular hip pain including femoroacetabular impingement, labral tears, cartilage defects, ligamentum teres injuries, snapping hip syndrome, femoral stress injuries, thigh splints, athletic pubalgia, avulsion injuries, and hip dislocation.

Magnetic resonance imaging of the hip: anatomy and pathology

The aim of this review is to outline the normal anatomy of the hip and to discuss common painful conditions of the hip that affect the general adult population. Hip pain is a common complaint with many different etiologies. In this review, hip pathologies are divided by location into osseous, intra-articular and extra-articular lesions. Magnetic resonance imaging (MRI) is the modality of choice for investigating painful hip conditions due to its multiplanar capability and high contrast resolution. This review focuses on the characteristic MRI features of common traumatic and pathologic conditions of the hip.

Hip Imaging in Athletes: Sports Imaging Series

Hip or groin pain in athletes is common and clinical presentation is often nonspecific. Imaging is a very important diagnostic step in the work-up of athletes with hip pain. This review article provides an overview on hip biomechanics and discusses strategies for hip imaging modalities such as radiography, ultrasonography, computed tomography, and magnetic resonance (MR) imaging (MR arthrography and traction MR arthrography). The authors explain current concepts of femoroacetabular impingement and the problem of high prevalence of cam- and pincer-type morphology in asymptomatic persons. With the main focus on MR imaging, the authors present abnormalities of the hip joint and the surrounding soft tissues that can occur in athletes: intraarticular and extraarticular hip impingement syndromes, labral and cartilage disease, microinstability of the hip, myotendinous injuries, and athletic pubalgia. (©) RSNA, 2016.

Longitudinal assessment of MRI in hip osteoarthritis using SHOMRI and correlation with clinical progression

PURPOSE

To assess the evolution of MR imaging findings in normal volunteers and subjects with hip osteoarthritis (OA) over 1.5 years described by the semi-quantitative Scoring Hip OA with MRI (SHOMRI) scoring system and their correlation with the evolution of clinical parameters.

MATERIALS AND METHODS

Hip MRI studies of 18 subjects with [Kellgren-Lawrence (KL) score = 2/3; mean age = 54.4 ± 11.2 years; 27.8% women] and 36 controls without radiographic OA [KL = 0/1; mean age = 43.7 ± 12.8 years; 50.0% women] were assessed at baseline and after 1.5 years by using SHOMRI, and their clinical status was evaluated by using Harris Hip Score and Hip Disability and Osteoarthritis Outcome Score (HOOS). Imaging and clinical parameters at baseline and their change over time were compared between groups using Mann-Whitney U and Fisher׳s exact tests. Spearman׳s rank correlations and generalized linear models adjusted for age, sex, BMI, and KL were used to assess associations between imaging and clinical findings.

RESULTS

At baseline, OA subjects had significantly higher SHOMRI total scores than controls [median (IQR): 12.5 (6-19.5) vs. 7 (4-13.5); p = 0.024]. Over 1.5 years, only the progression rate of subchondral cysts was significantly higher in OA subjects than in controls (16.7% vs. 0.0%; p = 0.033), while no significant differences were found for any of the other SHOMRI subscales. Baseline bone-marrow edema pattern (BMEP) was significantly associated with worsening pain (HOOS subscale; p = 0.018) and hip-related quality of life (HOOS subscale; p = 0.044). Progression of subchondral cysts was significantly associated with worsening symptoms other than pain (HOOS subscale, p = 0.030). Baseline KL did not significantly correlate with worsening of any clinical symptoms (each, p > 0.05).

CONCLUSION

In this relatively young study population without or with mild to moderate radiographic hip OA, only minimal differences were found between groups regarding the progression of hip abnormalities as assessed by SHOMRI over 1.5 years. However, BMEP predicted clinical worsening and subchondral cyst progression was associated with worsening symptoms. Although longer follow-up periods are required, this suggests that SHOMRI is a useful tool to monitor hip abnormalities and their progression longitudinally.

Magnetic Resonance Imaging of the Hip

Hip pain is common in all age groups, and osteoarthritis of this joint is an increasingly recognized problem particularly in aging populations. One of the primary goals in the diagnostic evaluation in patients with hip pain is to identify and correct pathologies that could progress to osteoarthritis. Magnetic resonance imaging (MRI) has become an important noninvasive method for characterizing hip anatomy and pathology in these patients. Improvements in MRI hardware and techniques have allowed high spatial and contrast resolution imaging to detect subtle abnormalities, such as acetabular labral and articular cartilage injuries, which often contribute to patient symptoms. Newer MRI techniques, such as delayed gadolinium-enhanced MRI of cartilage and T2 mapping, can give insight into the biochemical structure of tissues such as the articular cartilage. In turn, these can allow quantitative assessment and enable imagers to more directly compare the findings of patients at earlier stages of disease. It is important to understand the fundamental principles of various MRI techniques and their limitations to know when these techniques can best be applied. In addition, understanding of normal hip anatomy and common anatomic variants is useful for being able to accurately detect and localize areas of pathology and to prevent misinterpreting normal structures as diseased. The aims of this work were to briefly review normal hip anatomy and common anatomic variants seen on routine MRI examination, to discuss principles often used in high-resolution hip MRI and newer techniques for biochemical evaluation, and to examine several intra-articular pathologic conditions of the hip joint that are of current clinical interest.

Is labral hypotrophy correlated with increased acetabular depth?

Labral hypertrophy is a distinct feature in hip dysplasia. Occasionally, very small, hypotrophic labra are observed. However, there is no literature concerning this pathology. We investigated if the size of the labrum correlated with any radiologic parameters reflecting the amount of acetabular coverage. It was hypothezised that there is a negative correlation between labrum size and acetabular coverage. Labra were categorized into three groups depending on the relation between length of the articular sided surface and height of bony attachment. Labra with a height:length ratio of 2 were classified as hypotrophic, with a height:length ratio of 1 as normal and with a ratio of 0.5 as hypertrophic. Labral cross-sectional areas (CSA) were measured on radial magnetic resonance imaging-arthrography slices using the measuring tool of the PACS system of 20 hips with hypotrophic labra (group 1), 20 hips with normal labral appearance (group 2) and 10 hips with hypertrophic labra (group 3). These values were then analyzed against following parameters: neck-shaft-angle (NSA), lateral center-edge angle (LCE), acetabular index (AI), femoral extrusion index (FEI) and acetabular retroversion index (ARI). Analyses of variance were used to determine differences in mean values between the three groups. Mean labral CSA differed significantly between all groups (group 1: 12.1 ± 2.9 mm²; group 2: 25.2 ± 6.2 mm²; group 3: 41.1 ± 12.3 mm²; P < 0.001). NSA, LCE, AI and FEI all showed a significant difference between group 3 and 1 or 2. The ARI showed no difference between groups. Stepwise linear regression analyses showed a significant correlation between LCE angle and labral CSA with a corrected R²-value of 0.301. Labral CSA correlates with the LCE. No statistically significant difference between groups 1 and 2 concerning the LCE, AI or FEI could be identified. Nevertheless, group 1 had the highest mean coverage of all groups, hips with hypertrophic labra the lowest.

OARSI Clinical Trials Recommendations: Hip imaging in clinical trials in osteoarthritis

Imaging of hip in osteoarthritis (OA) has seen considerable progress in the past decade, with the introduction of new techniques that may be more sensitive to structural disease changes. The purpose of this expert opinion, consensus driven recommendation is to provide detail on how to apply hip imaging in disease modifying clinical trials. It includes information on acquisition methods/techniques (including guidance on positioning for radiography, sequence/protocol recommendations/hardware for magnetic resonance imaging (MRI)); commonly encountered problems (including positioning, hardware and coil failures, artifacts associated with various MRI sequences); quality assurance/control procedures; measurement methods; measurement performance (reliability, responsiveness, and validity); recommendations for trials; and research recommendations.

MRI of the hip at 7T: feasibility of bone microarchitecture, high-resolution cartilage, and clinical imaging

PURPOSE

To demonstrate the feasibility of performing bone microarchitecture, high-resolution cartilage, and clinical imaging of the hip at 7T.

MATERIALS AND METHODS

This study had Institutional Review Board approval. Using an 8-channel coil constructed in-house, we imaged the hips of 15 subjects on a 7T magnetic resonance imaging (MRI) scanner. We applied: 1) a T1-weighted 3D fast low angle shot (3D FLASH) sequence (0.23 × 0.23 × 1-1.5 mm(3) ) for bone microarchitecture imaging; 2) T1-weighted 3D FLASH (water excitation) and volumetric interpolated breath-hold examination (VIBE) sequences (0.23 × 0.23 × 1.5 mm(3) ) with saturation or inversion recovery-based fat suppression for cartilage imaging; 3) 2D intermediate-weighted fast spin-echo (FSE) sequences without and with fat saturation (0.27 × 0.27 × 2 mm) for clinical imaging.

RESULTS

Bone microarchitecture images allowed visualization of individual trabeculae within the proximal femur. Cartilage was well visualized and fat was well suppressed on FLASH and VIBE sequences. FSE sequences allowed visualization of cartilage, the labrum (including cartilage and labral pathology), joint capsule, and tendons.

CONCLUSION

This is the first study to demonstrate the feasibility of performing a clinically comprehensive hip MRI protocol at 7T, including high-resolution imaging of bone microarchitecture and cartilage, as well as clinical imaging.