Comparison of 3T MR arthrography and 3T MRI in intra-articular hip pathology: a cost-analysis

BACKGROUND

MR arthrography (MRA) has previously been the radiological gold standard for investigating labral and chondral lesions of the hip joint. In recent years, 3T MRI has demonstrated comparable accuracy, being adopted as the first-line imaging investigation in many institutions.

AIMS

We compare the associated increased cost and radiation dose of the fluoroscopic component of the MRA compared to MRI.

METHODS

In this retrospective review over 2 years, 120 patients (mean age 27.3 years ± 13.2, range 8-67) underwent 3T MRA or non-contrast 3T MRI. Three musculoskeletal radiologists reported the data independently. Primary objectives included cost-comparison between each and radiation dose of the fluoroscopic component of the MRA. Secondary objectives included comparing detection of pathology involving the acetabular labrum, femoral cartilage, and acetabular cartilage.

RESULTS

Then, 58 (48%) underwent 3T MRA and 62 (52%) patients underwent 3T MRI. The added cost of the fluoroscopic injection prior to MRA was €116.31/patient, equating to €7211.22 savings/year. MRA was associated with a small radiation dose of 0.003 mSv.

CONCLUSIONS

Transitioning from 3T MRA to 3T MRI in the investigation of intra-articular hip pathology increases cost savings and reduces radiation dose.

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.

[Direct MR Arthrography of the Hip: Diagnosis and Pitfalls of Acetabular Labral Lesions]

Tearing of the acetabular labrum is a common cause of chronic hip pain. MR arthrography (MRA) of the hip is the imaging procedure of choice for the evaluation of acetabular labrum. Familiarity with the various imaging findings of MRA of the hip allows recognition of normal variants and differentiation from true pathologic conditions. This article comprehensively reviews the technical aspects and interpretation of MRA of the hip. The appearances of normal and abnormal labra in MRA are discussed. Potential pitfalls in labral tear interpretation, such as sulci around the hip, normal variants of the labrum and plicae, and osseocartilaginous and soft tissue lesions identified on MRA of the hip are also described.

Ultrasonography-guided intra-articular steroid injection in the hip for symptomatic round ligament partial tear or degeneration

Purpose

The objectives of this study were to demonstrate the benefits of ultrasonography-guided intra-articular steroid injection in the hip (UISIH) for the treatment of partial tear or degeneration of the round ligament of the femur and to determine the prognostic factors for this treatment.

Methods

We retrospectively analyzed the records of 40 patients who were diagnosed with a partial tear or degeneration of the round ligament of the femur and who underwent UISIH between August 2014 and November 2018. The inclusion criteria were a lack of history of UISIH or other interventional procedure and the presence of follow-up records after the hip injection. The short-term clinical outcome was evaluated at the first follow-up appointment after UISIH. Possible prognostic factors for UISIH such as age, sex, injection side, and average follow-up time were analyzed using the chi-square test, the Fisher exact test, and the t test.

Results

UISIH was found to have been effective in 35 of the 40 patients (87.5%) at the first follow-up visit. The average follow-up time was 43 days. No significant differences were observed in the clinical outcome of UISIH with respect to age, sex, injection side, or follow-up time.

Conclusion

In this study, we demonstrated that UISIH was a safe and effective treatment in patients with a partial tear or degeneration of the round ligament of the femur over the course of short-term follow-up. Age, sex, injection side, and follow-up time were not identified as prognostic factors for this treatment.

Non-traumatic ligamentum teres tears: association with MRI morphometry of the hip

BACKGROUND

The ligamentum teres has been recognized as an important stabilizer of the hip.

PURPOSE

We aimed to examine the relationship between non-traumatic ligamentum teres (LT) tear and hip morphometry on magnetic resonance imaging (MRI).

MATERIAL AND METHODS

Fifty patients who had undergone hip MRI were included (27 men, 23 women; average age = 54.0 years). The status of the LT and the morphometric hip parameters were assessed, including acetabular anteversion angle (AAA), acetabular depth (AD), acetabular index (AI), lateral center edge angle (LCEA), and extrusion index (EI). The morphometric hip parameters were compared between groups with one-way ANOVA, Student's t-test, and Mann-Whitney U test.

RESULTS

A decreased acetabular coverage was noted in the severe tear group compared to the normal group, indicated by a significantly larger AD ( P = 0.001) and smaller LCEA ( P = 0.016). There was a statistically significant difference in the AAA, AD, and LCEA between the normal group and the complete tear group; the AAA was significantly larger ( P = 0.031), the AD was significantly larger ( P = 0.01), and the LCEA was significantly smaller ( P = 0.043) in the complete tear group compared to the normal group.

CONCLUSION

There is an association between LT tears and acetabular bony morphology; an insufficient acetabular coverage is associated with complete tear of the LT. As the insufficient acetabular coverage may predispose to ligamentum teres tear, the ligamentum teres should be thoroughly evaluated in those with insufficient acetabular coverage, as a potential cause of hip pain.

Hip pathology: the diagnostic accuracy of magnetic resonance imaging

Background

Hip arthroscopy has led to a greater understanding of intra-articular hip pathology. Non-contrast magnetic resonance imaging (MRI) is currently the gold standard in non-invasive imaging diagnosis, with high sensitivity in identifying labral pathology but equivocal results for ligamentum teres damage and chondral defects.

The aim of this study is to determine the accuracy of non-contrast MRI for diagnosis of intra-articular hip derangements and identify radiological features that could increase the accuracy of the diagnosis.

Methods

A prospective study of 71 hips on 68 patients undergoing hip arthroscopy was conducted comparing pre-operative analysis of MRI imaging versus an arthroscopic examination. Two musculoskeletal radiologists reported the data independently. All hip arthroscopies were performed by a single surgeon. Patients with MRIs performed within 6 months before hip arthroscopy were included.

Outcome measures included observer accuracy identifying ligamentum teres tears, labral lesions, and chondral rim damage. Secondary outcome measures included inter-observer variability and correctly staged ligamentum teres tears.

Results

The accuracy of radiology reporting for ligamentum teres tears, labral damage, and chondral rim lesions was 85.92% for each instance. The MRI findings most consistent with labral tears include the presence of linear high signal traversing the articular surface into the labrum, presence of intra-labral fluid signal, and loss of homogenous low signal triangular morphology. Chondral rim damage was difficult to diagnose, but abnormal signal at the chondrolabral junction with partial thickness defects would suggest damage. Ligamentum teres tears are commonly found but poorly graded. Thickening and increased signal suggests synovitis while discontinuity and fraying suggests partial tearing.

Conclusion

Conventional non-arthrographic MRI offers an accurate non-invasive method to screen patients with symptoms referable to the hip by revealing the presence of labral tears, chondral defects, and ligamentum teres tears/synovitis. This study demonstrates that tears and synovitis of the ligamentum teres as potential sources of hip pain can be accurately identified on conventional non-arthrographic MRI. However, MRI has poor specificity and negative predictive value, and thus, a negative MRI result may warrant further investigation.

Sports Injuries about the Hip: What the Radiologist Should Know

Injuries of the hip and surrounding structures represent a complex and commonly encountered scenario in athletes, with improper diagnosis serving as a cause of delayed return to play or progression to a more serious injury. As such, radiologists play an essential role in guiding management of athletic injuries. Familiarity with hip anatomy and the advantages and limitations of various imaging modalities is of paramount importance for accurate and timely diagnosis. Magnetic resonance (MR) imaging is often the modality of choice for evaluating many of the injuries discussed, although preliminary evaluation with conventional radiography and use of other imaging modalities such as ultrasonography (US), computed tomography, and bone scintigraphy may be supplementary or preferred in certain situations. Stress fractures, thigh splints, and posterior hip dislocations are important structural injuries to consider in the athlete, initially imaged with radiographs and often best diagnosed with MR imaging. Apophyseal injuries are particularly important to consider in young athletes and may be acute or related to chronic repetitive microtrauma. Femoroacetabular impingement has been implicated in development of labral tears and cartilage abnormalities. Tear of the ligamentum teres is now recognized as a potential cause of hip pain and instability, best evaluated with MR arthrography. Greater trochanteric pain syndrome encompasses a group of conditions leading to lateral hip pain, with US playing an increasingly important role for both evaluation and image-guided treatment. Muscle injuries and athletic pubalgia are common in athletes. Lastly, snapping hip syndrome and Morel-Lavallée lesions are two less common but nonetheless important considerations. ^©RSNA, 2016.

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.

Ligamentum teres tendinopathy and tears

BACKGROUND

The ligamentum teres (LT) consists of two bands that originate on the ischial and pubic sides of the acetabular notch and insert on the fovea capitis of the femoral head. Recent studies have established the LT as an important hip stabilizer in a squatting position, particularly in patients with osseous instability.

PURPOSE

This review aims to concisely present the literature on LT tendinopathy and tears in order to guide health care professionals in the appropriate diagnosis and treatment of these disorders.

METHODS

We reviewed the literature on the diagnosis and surgical management of ligamentum teres tendinopathy and tears.

CONCLUSIONS

The ligamentum teres is an important stabilizer to the hip joint, particularly with hip flexion and external rotation. Older age and acetabular bony pathomorphology are two of the known risk factors for LT tears. Symptoms of LT tendinopathy are largely non-specific, mimicking a wide range of other hip disorders including impingement and instability. Debridement of LT tears or reactive tissue has been reported with good outcomes, with more recent studies describing reconstruction of a completely torn, nonfunctional, or absent LT using various graft sources including synthetic grafts, autografts, and allografts.

LEVEL OF EVIDENCE

II.

Hip instability: a review of hip dysplasia and other contributing factors

BACKGROUND

Hip instability has classically been associated with developmental dysplasia of the hip (DDH) in newborns and children. However, numerous factors may contribute to hip instability in children, adolescents, and adults.

PURPOSE

This review aims to concisely present the literature on hip instability in patients of all ages in order to guide health care professionals in the appropriate diagnosis and treatment of the various disorders which may contribute to an unstable hip.

METHODS

We reviewed the literature on the diagnosis and surgical management of hip dysplasia and other causes of hip instability.

CONCLUSIONS

Multiple intra- and extra-articular variables may contribute to hip instability, including acetabular bony coverage, femoral torsion, femoroacetabular impingement, and soft tissue laxity. Physical examination and advanced imaging studies are essential to accurately diagnose the pathology contributing to a patient's unstable hip. Conservative management, including activity modification and physical therapy, may be used as a first-line treatment in patients with intra-articular hip pathology. Patients who continue to experience symptoms of pain or instability should proceed with arthroscopic or open surgical treatment aimed at correcting the underlying pathology.

LEVEL OF EVIDENCE

V.

Atraumatic tears of the ligamentum teres are more frequent in professional ballet dancers than a sporting population

OBJECTIVES

To compare the frequency of atraumatic ligamentum teres (LT) tear in professional ballet dancers with that of athletes, and to determine the relationship with clinical and imaging findings.

METHODS

Forty-nine male and female professional ballet dancers (98 hips) and 49 age and sex-matched non-dancing athletes (98 hips) completed questionnaires on hip symptoms and physical activity levels, underwent hip rotation range of movement (ROM) and hypermobility testing, and 3.0-Tesla magnetic resonance imaging (3 T MRI) on both hips to detect LT tears, acetabular labral tears, and articular cartilage defects, and to measure the lateral centre edge angles (LCE).

RESULTS

A higher frequency of LT tear was found in dancers (55 %) compared with athletes (22 %, P = 0.001). The frequency and severity of LT tears in dancers increased with older age (P = 0.004, P = 0.006, respectively). The Hip and Groin Outcome Score (HAGOS) pain scores or hip rotation ROM did not differ significantly among participants with normal, partial, or complete tears of LT (P > 0.01 for all). Neither the frequency of generalised joint hypermobility (P = 0.09) nor the LCE angles (P = 0.32, P = 0.16, left and right hips respectively) differed between those with and those without LT tear. In most hips, LT tear co-existed with either a labral tear or a cartilage defect, or both.

CONCLUSION

The higher frequency of atraumatic LT tears in professional ballet dancers suggests that the LT might be abnormally loaded in ballet, and caution is required when evaluating MRI, as LT tears may be asymptomatic. A longitudinal study of this cohort is required to determine if LT tear predisposes the hip joint to osteoarthritis.

Magnetic resonance arthrography of the hip: prevalence of diagnoses not suspected by the referring physician and correlation with clinical examination and pain score

BACKGROUND

Magnetic resonance arthrography (MRA) of the hip is the most sensitive imaging modality for intra-articular pathologies such as labral tears.

PURPOSE

To evaluate the prevalence of non-suspected pathologies revealed by hip MRA and correlate them to physical examination/pain level.

MATERIAL AND METHODS

All hip MRAs (2011-2013) were retrospectively evaluated for intra- and extra-articular pathologies in consensus by two readers. A clinical score (0-7)/pain score (0-10) was calculated for each patient based on orthopedic test results extracted from referral forms/a telephone questionnaire. Patients were divided into four groups according to MRA findings: intra-articular expected (targeted) pathology only; intra-articular targeted and additional non-targeted (unexpected) pathology; non-targeted pathology; and no pathology. Pathologies prevalence/clinical score/pain score were compared between the groups.

RESULTS

A total of 229 MRAs were included (127 men, 102 women; mean age, 36.5 ± 14.17 years): 111(48.4%) patients had solely intra-articular targeted pathology. Significant non-targeted pathologies were detected in 76 (33%) patients (targeted and non-targeted, 51; non-targeted only 25). No significant pathology was detected in 42 patients (18%). Mean physical examination score was 2.77 ± 1.77, range 0-7. There was no significant difference or correlation (r = 0.017, P = 0.804) between the clinical scores of the different MRA pathology groups. Pain score (143 patients) was significantly higher in the non-targeted pathology group compared to the targeted and non-targeted group (P = 0.04) and to the no pathology group (P = 0.04). There was no correlation between the physical examination score and the pain score (r = 0.017, P = 0.804).

CONCLUSION

Unsuspected non-targeted pathologies were detected in 33% of hip MRA. Physical examination/pain level could not differentiate between patients.

MR arthrography of the hip with and without leg traction: Assessing the diagnostic performance in detection of ligamentum teres lesions with arthroscopic correlation

OBJECTIVES

To retrospectively assess the diagnostic performance of hip MR arthrography with and without traction in detecting ligamentum teres (LT) lesions with arthroscopic correlation and to evaluate the effect of traction on the imaging appearance of the LT.

METHODS

73 MR arthrograms (73 consecutive patients, mean age, 34.5 years; range, 14-55 years) obtained without and with leg traction (application of 15-23 kg, use of a supporting plate for the contralateral leg) were included. Two blinded readers independently evaluated LT lesions on MR arthrograms on separate occasions: coronal images without traction; coronal images with traction; a multiplanar traction protocol. MR findings were correlated with arthroscopic records. Sensitivity/specificity of traction and non-traction imaging was compared on coronal images with the exact McNemar test. Imaging appearance of the LT with and without traction was assessed in consensus and compared on coronal images using McNemar and McNemar-Bowker tests. (p<0.05, * corrected for type I error).

RESULTS

With arthroscopy 29 (40%) LT lesions were identified in 73 patients. Sensitivity was 72%/90% (without traction/with traction; p=0.25*), specificity was 89%/77% (p=0.25*) for reader 1 in assessing coronal images and for reader 2 sensitivity was 59%/86% (p=0.044*) and specificity was 93%/82% (p=0.25*). Alterations in fiber orientation, signal intensity, surface, dimension, fiber continuity after application of traction were observed in 33/73 (45%, p=0.002*), 6/73 (8%, p=0.223), 9/73 (12%, p=0.36*), 6/73 (8%, p=0.031) respectively 9/73 (12%, p=0.003) cases. Traction-related alterations in at least one criterion were observed in 41/73 (56%) cases.

CONCLUSION

Application of traction can considerably alter the imaging appearance of the LT and resulted in higher rates of true-positive and false-positive findings compared to conventional MR arthrography.

Usefulness of MR arthrography of the hip with leg traction in the evaluation of ligamentum teres injuries

PURPOSE

To retrospectively evaluate the diagnostic accuracy of magnetic resonance (MR) arthrography of the hip with leg traction in the evaluation of ligamentum teres lesions and to evaluate whether there is increased articular distraction, possibly indicating secondary instability, in hips with ligamentum teres injuries.

MATERIALS AND METHODS

Institutional review board approval and informed consent were obtained for this retrospective study. MR arthrograms of the hip with leg traction of 184 consecutive patients, including 108 men (mean age, 32.6 years; range, 19-53 years) and 76 women (mean age, 38.5 years; range, 18-56 years), who underwent hip arthroscopy were assessed for the presence of ligamentum teres lesions. The MR arthrographic findings were independently assessed by two radiologists who were blinded to the arthroscopic results. The inclusion criteria stipulated no previous surgery, arthroscopy within 1 month after MR arthrography, and availability of a detailed surgical report with ligamentum teres findings. The arthroscopy findings served as the reference standard. Sensitivity, specificity, accuracy, and K statistics for interobserver and intraobserver agreement were calculated.

RESULTS

At arthroscopy, 32 ligamentum teres injuries were found. The ligamentum teres was normal in 152 (82.6%) patients and had suffered low-grade partial tears in 15 (8.1%) patients, high-grade partial tears in 10 (5.4%) patients, and complete ruptures in 7 (3.8%) patients. MR arthrography with axial traction demonstrated moderate sensitivity and high specificity for both low-grade (62/93%) and high-grade (66/96%) partial tears. Grouping low- and high-grade partial tears increased the diagnostic performance of MR arthrography, yielding a sensitivity of 87% and a specificity of 95%. For complete ligamentum teres tears, MR arthrography with leg traction demonstrated high sensitivity (92%) and specificity (98%). Articular distraction was significantly increased in patients with complete ruptures of the ligamentum teres (p = 0.001).

CONCLUSION

MR arthrography with leg traction offers accurate diagnosis of ligamentum teres injuries. Patients with complete tears of the ligamentum teres exhibit increased articular distraction that may indicate secondary hip instability.

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.

Use of MR arthrography in detecting tears of the ligamentum teres with arthroscopic correlation

OBJECTIVE

To demonstrate the normal appearance of the ligamentum teres on MR arthrography (MRA) and evaluate the accuracy of MRA in detecting ligamentum teres tears with arthroscopic correlation.

MATERIALS AND METHODS

Institutional Review Board approval was obtained with a waiver for informed consent because of the retrospective study design. A total of 165 cases in 159 patients (111 females, 48 males; mean age 41 ± 12 years) who underwent both MRA and hip arthroscopy were evaluated for appearance of the ligamentum teres, including the size, number of bundles, and ligamentum teres tears. Marrow edema of the fovea capitis adjacent to the ligamentum teres insertion and the presence of hip plicae were also recorded.

RESULTS

The mean thickness and length of the ligamentum teres were 3.5 ± 1.5 mm and 25.2 ± 3.8 mm, respectively. Sensitivity, specificity, positive and negative predictive value, and accuracy of MRA for the detection of ligamentum teres tears were 78, 97, 74, 97, and 95%, respectively.

CONCLUSION

MRA is an accurate method to evaluate the normal morphology and to detect tears of the ligamentum teres.