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.

Direct MR arthrography without image guidance: a practical guide, joint-by-joint

Direct MR arthrography (dMRA) is a fundamental technique in diagnosing pathology in major peripheral joints, allowing for precise evaluation of intra-articular structures. Although injection guidance is typically performed using imaging techniques such as ultrasound or fluoroscopy, puncture via anatomical landmarks may be useful in certain circumstances where it has been proven to be a safe and effective procedure. This paper describes the indications and injection technique of dMRA, joint by joint, focusing on the different technical details, from the most common locations, like the shoulder or hip, to those with more restricted clinical indications, such as the wrist, knee, elbow, or ankle. The most relevant anatomical landmarks are detailed for each joint, aiding in the intra-articular introduction of diluted contrast, highlighting the most accessible trajectories and structures to avoid when inserting the needle. Additionally, tips are provided to facilitate proper joint distension. With all this information, this paper aims to serve as a suitable reference guide for performing dMRA without image guidance if needed.

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.

Magnetic Resonance Imaging and Magnetic Resonance Arthrography Are Both Reliable and Similar When Measuring Hip Capsule Thickness in Patients With Femoroacetabular Impingement Syndrome

Purpose

To propose an accurate method of measuring hip capsular thickness in patients with femoroacetabular impingement syndrome and to compare the reliability of these measurements between magnetic resonance imaging (MRI) and magnetic resonance arthrography (MRA).

Methods

A previously established database of patients with femoroacetabular impingement syndrome (FAIS) was used to identify candidates with preoperative MRI or MRA from November 2018 to June 2021. Two reviewers independently examined preoperative imaging for 85 patients. Capsular thickness was measured in 12 standardized locations. Intraclass correlation coefficients (ICCs) were calculated using an absolute-agreement, 2-way random-effects model. Using the same method, 30 patients were randomly selected for repeat measurements by 1 reviewer following a washout period. Ten additional patients with preoperative MRI and MRA of the same hip were identified to compare measurements between modalities using paired samples t test.

Results

ICCs for measurements on MRIs and MRAs using these proposed measurements to compare inter-rater reliability were 0.981 and 0.985. ICCs calculated using measurements by a single reviewer following a washout period for intrarater reliability were 0.998 and 0.991. When comparing MRI and MRA measurements in the same patient, t test for all pooled measurements found no difference between modality (P = .283), and breakdown of measurements by quadrant found no difference in measurements (P > .05), with the exception of the inferior aspect of the capsule on coronal sequences (P = .023).

Conclusions

In patients with FAIS, both MRI and MRA have excellent reliability for quantifying hip capsular thickness. A difference in capsular thickness was found only when comparing MRI and MRA on inferior coronal aspects of the hip capsule, indicating interchangeability of these imaging modalities when measuring the clinically important aspects of the hip capsule.

Level of Evidence

Level IV, diagnostic case series.

SSR white paper: guidelines for utilization and performance of direct MR arthrography

OBJECTIVE

Direct magnetic resonance arthrography (dMRA) is often considered the most accurate imaging modality for the evaluation of intra-articular structures, but utilization and performance vary widely without consensus. The purpose of this white paper is to develop consensus recommendations on behalf of the Society of Skeletal Radiology (SSR) based on published literature and expert opinion.

MATERIALS AND METHODS

The Standards and Guidelines Committee of the SSR identified guidelines for utilization and performance of dMRA as an important topic for study and invited all SSR members with expertise and interest to volunteer for the white paper panel. This panel was tasked with determining an outline, reviewing the relevant literature, preparing a written document summarizing the issues and controversies, and providing recommendations.

RESULTS

Twelve SSR members with expertise in dMRA formed the ad hoc white paper authorship committee. The published literature on dMRA was reviewed and summarized, focusing on clinical indications, technical considerations, safety, imaging protocols, complications, controversies, and gaps in knowledge. Recommendations for the utilization and performance of dMRA in the shoulder, elbow, wrist, hip, knee, and ankle/foot regions were developed in group consensus.

CONCLUSION

Although direct MR arthrography has been previously used for a wide variety of clinical indications, the authorship panel recommends more selective application of this minimally invasive procedure. At present, direct MR arthrography remains an important procedure in the armamentarium of the musculoskeletal radiologist and is especially valuable when conventional MRI is indeterminant or results are discrepant with clinical evaluation.

The use of slice encoding for metal artifact correction (SEMAC) sequencing improves the diagnostic evaluation of graft integrity following anterior cruciate ligament reconstruction

OBJECTIVES

To determine whether magnetic resonance imaging (MRI) with metal artifact reduction sequencing is superior to conventional knee MRI in the evaluation of an injured anterior cruciate ligament (ACL) graft, where visualisation on conventional MRI can be limited by the metal artifact from fixation devices.

METHODS

Eighteen patients underwent conventional MRI sequence (proton density fat saturated [PDFS]) and two types of metal artifact reduction sequencing MRI (WARP, slice encoding for metal artifact correction (SEMAC); Siemens) following a secondary injury to their ACL reconstructed knee. Six raters with experience in knee MRI evaluation reviewed sagittal PDFS, WARP, and SEMAC sequences, providing semi-quantitative grades for visualisation and diagnostic confidence assessing the ACL, posterior cruciate ligament , menisci, tibial and femoral tunnel margins, and articular cartilage. Intra-class correlation coefficients for inter-rater reliability were evaluated. The 6-rater mean scores for the visualisation and diagnostic confidence derived from each sequence were compared using the Friedman test for multiple paired samples.

RESULTS

No statistically significant difference in the ACL visualisation among the sequences was found (p ​= ​0.193). Further, a subgroup analysis was performed in cases evaluated as "moderately blurry" or "indistinct ACL visualisation" on PDFS (58% of cases). SEMAC significantly improved diagnostic confidence in ACL visualisation (p ​= ​0.041) and ACL graft rupture (p ​= ​0.044) compared to PDFS. There was no statistically significant difference in the inter-observer reliability between sequences. The WARP sequence added 2.84 ​± ​0.69 ​min, while SEMAC added 2.95 ​± ​0.40 ​min to the standard knee MRI scan time.

CONCLUSION

use of the SEMAC metal reduction sequence significantly improved diagnostic accuracy and confidence in the detection of ACL graft rupture in cases where the ACL was moderately blurry or indistinct on the PDFS sequence. This sequence should be considered as an adjunct to conventional PDFS in cases where graft visualisation is limited by the metal artifact from fixation devices.

LEVEL OF EVIDENCE

III.

Trends in MR Arthrogram Utilization at a Tertiary Care Academic Center

The purpose is to evaluate the trends in MR arthrogram utilization at a tertiary care academic institution and to determine if there are factors that can be implicated in the utilization trends. Number of MR arthrograms of the shoulder, hip, and elbow from 2013-2020 at our institution were identified (n = 1882). Patient demographics including age, sex, sports participation, history of prior surgery, and physician referral were obtained. Descriptive statistics were performed to determine the prevalence of MR arthrograms. Linear regression analyses were performed to determine the relationship of time with prevalence of arthrograms. Chi-square tests and posthoc analyses with Bonferroni correction were used to assess if categorical variables were different between the years. There was overall decrease in the prevalence of MR arthrograms of the shoulder, hip, and elbow despite an increase in the overall MR volume during the study period. Linear regression models significantly predicated decrease in arthrogram prevalence with each passing year (P < 0.001). The percentage of orthopedic referrals for arthrograms in the hip (P = 0.002) and shoulder (P = < 0.001) decreased significantly towards the end of the study period. None of the other variables assessed were significant. At our tertiary care academic institution, arthrogram utilization has been drastically decreasing over the past 8 years. The percentage of orthopedic referrals for shoulder and hip arthrograms significantly decreased at the end of the study period.

Can gadolinium contrast agents be replaced with saline for direct MR arthrography of the hip? A pilot study with arthroscopic comparison

OBJECTIVE

To compare image quality and diagnostic performance of preoperative direct hip magnetic resonance arthrography (MRA) performed with gadolinium contrast agent and saline solution.

METHODS

IRB-approved retrospective study of 140 age and sex-matched symptomatic patients with femoroacetabular impingement, who either underwent intra-articular injection of 15-20 mL gadopentetate dimeglumine (GBCA), 2.0 mmol/L ("GBCA-MRA" group, n = 70), or 0.9% saline solution ("Saline-MRA" group, n = 70) for preoperative hip MRA and subsequent hip arthroscopy. 1.5 T hip MRA was performed including leg traction. Two readers assessed image quality using a 5-point Likert scale (1-5, excellent-poor), labrum and femoroacetabular cartilage lesions. Arthroscopic diagnosis was used to calculate diagnostic accuracy which was compared between groups with Fisher's exact tests. Image quality was compared with the Mann-Whitney U tests.

RESULTS

Mean age was 33 years ± 9, 21% female patients. Image quality was excellent (GBCA-MRA mean range, 1.1-1.3 vs 1.1-1.2 points for Saline-MRA) and not different between groups (all p > 0.05) except for image contrast which was lower for Saline-MRA group (GBCA-MRA 1.1 ± 0.4 vs Saline-MRA 1.8 ± 0.5; p < 0.001). Accuracy was high for both groups for reader 1/reader 2 for labrum (GBCA-MRA 94%/ 96% versus Saline-MRA 96%/93%; p > 0.999/p = 0.904) and acetabular (GBCA-MRA 86%/ 83% versus Saline-MRA 89%/87%; p = 0.902/p = 0.901) and femoral cartilage lesions (GBCA-MRA 97%/ 99% versus Saline-MRA 97%/97%; both p > 0.999).

CONCLUSION

Diagnostic accuracy and image quality of Saline-MRA and GBCA-MRA is high in assessing chondrolabral lesions underlining the potential role of non-gadolinium-based hip MRA.

KEY POINTS

• Image quality of Saline-MRA and GBCA-MRA was excellent for labrum, acetabular and femoral cartilage, ligamentum teres, and the capsule (all p > 0.18). • The overall image contrast was lower for Saline-MRA (Saline-MRA 1.8 ± 0.5 vs. GBCA-MRA 1.1 ± 0.4; p < 0.001). • Diagnostic accuracy was high for Saline-MRA and GBCA-MRA for labrum (96% vs. 94%; p > 0.999), acetabular cartilage damage (89% vs. 86%; p = 0.902), femoral cartilage damage (97% vs. 97%; p > 0.999), and extensive cartilage damage (97% vs. 93%; p = 0.904).

Gadolinium injected concurrently with anesthetic can result in false-negative diagnostic intra-articular hip injections

PURPOSE

The purpose of this paper was to evaluate the response to intra-articular hip injections with and without concurrent gadolinium administration. Our secondary outcome was to compare post-operative outcomes between patients with an initial false-negative gadolinium-containing injection and a matched control group.

METHODS

Patients receiving a series of two hip diagnostic intra-articular injections (DIAI), the first with gadolinium for concurrent MRA and the second without gadolinium, were retrospectively identified. Pain response to DIAI, injectate volume, local anesthetic volume, inclusion of corticosteroids, and method of injection were compared between injections. False-negative injection was defined as < 50% pain relief with concurrent gadolinium, but ≥ 50% pain relief with subsequent anesthetic injection without gadolinium. False-negative injections in patients that ultimately underwent primary hip arthroscopy were identified from this cohort and matched in a 3:1 ratio to a control cohort to compare short-term post-operative single assessment numerical evaluation (SANE) outcomes.

RESULTS

Forty-three patients underwent a series of anesthetic injections with and without gadolinium and met inclusion and exclusion criteria. Pain response was significantly different in injections performed with and without gadolinium (18% vs. 81%; p < 0.001). There were significant differences in total injectate volume, local anesthetic volume, corticosteroid use, and method of injection between injections, but these variables were not correlated with pain response. Fifteen patients with false-negative responses to injection underwent primary hip arthroscopy and were matched in a 3:1 ratio to a control cohort. There was no difference in short-term post-operative SANE scores between the gadolinium-sensitive and control groups (81.6 vs. 80.0, n.s.).

CONCLUSION

Concurrent administration of intra-articular gadolinium with DIAI may result in a false-negative response to anesthetic. Additionally, in patients with initial false-negative DIAI with gadolinium, short-term post-operative outcomes after hip arthroscopy are similar to a matched cohort.

LEVEL OF EVIDENCE

Level III.

How Safe Is Gadobutrol? Examining the Effect of Gadolinium Deposition on the Nervous System

This study aimed to evaluate the safety of gadobutrol, a gadolinium-based contrast agent used in medical imaging, by investigating its effect on the nervous system under physiological and inflammatory conditions. Male Sprague Dawley rats were divided randomly into four groups, including gadobutrol, saline, LPS + gadobutrol, and LPS + saline, and were given intraperitoneal injections of gadobutrol (2.5 mmol/kg) or saline for 20 days. Weekly sensorimotor and cognitive behavioral tests were performed over 4 weeks, and Gd concentration in nervous tissues was analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Lactate dehydrogenase (LDH) activity was measured to evaluate cytotoxicity, and electromyography (EMG) recordings from the gastrocnemius muscle were also obtained to examine signal transmission in sciatic nerves. The results indicated that gadobutrol did not induce significant behavioral changes under normal conditions. However, when administered along with LPS, the combination led to behavioral dysfunction. ICP-MS analysis revealed a higher concentration of Gd in the cerebrum and spinal cord of gadobutrol + LPS-treated rats, while peripheral nerves showed lower concentrations. In addition, there was a significant increase in LDH activity in the hippocampus of the gadobutrol group. EMG responses to electrical stimulation of the sciatic nerve demonstrated a decreased threshold of nociceptive reflexes in the gadobutrol group. Overall, while gadobutrol may be considered safe under normal physiological conditions, the findings suggest that its safety may be compromised under inflammatory conditions.

Improving visualization of the articular cartilage of the knee with magnetic resonance imaging under axial traction: a comparative study of different traction weights

OBJECTIVE

Lesions of the articular cartilage of the knee, especially early grades, are not always accurately detected by magnetic resonance imaging (MRI) because of contact between the articular cartilage surfaces of the femur and the tibia. This study aimed to assess the effects of axial leg traction during knee MRI examination on joint space widening and articular cartilage visualization and evaluate the ideal weight for traction.

METHODS

MRI was performed on ten healthy volunteers using a 3-T MRI unit with a 3D dual-echo steady-state gradient-recalled echo sequence. Conventional MRI was performed first, followed by traction MRI. The traction weight increased in the order of 5 kg, 10 kg, and 15 kg. Joint space widths were measured, and articular cartilage visualization was assessed at the medial and lateral tibiofemoral joints. Volunteers were asked to evaluate pain and discomfort using a visual analog scale during each procedure with axial traction to assess the safety of traction MRI.

RESULTS

The medial tibiofemoral joint space width significantly increased, and the visualization of the articular cartilage significantly improved by applying traction. The joint space width and the articular cartilage visualization showed no significant differences among traction weights of 5 kg, 10 kg, and 15 kg. Pain and discomfort during traction MRI examination were lowest with a traction weight of 5 kg.

CONCLUSION

Traction MRI examination may be useful in evaluating articular cartilage lesions at the medial tibiofemoral joint. A traction weight of 5 kg may be sufficient with minimum pain and discomfort.

Radio-carpal wrist MR arthrography: comparison of ultrasound with fluoroscopy and palpation-guided injections

OBJECTIVE

To compare ultrasound- (US), fluoroscopy- (FL), and palpation-guided contrast injection techniques used for dorsal radio-carpal wrist MRA.

MATERIALS AND METHODS

Patients with chronic wrist pain were randomized as to which injection technique they underwent into three groups of 50 participants. Dorsal radio-carpal contrast injection was performed under US, FL guidance (one radiologist for each), or palpation guidance by an orthopedic surgeon. The three techniques were compared by procedure time, success rate, number of attempts needed, frequency and grade of extravasation, joint distension, and MRA image quality. Additionally, any change from baseline wrist pain was recorded using the visual analog scale (VAS) at five time points (immediately, 8 h, 24 h, 48 h, and 1 week) after injection.

RESULTS

One hundred and fifty patients (83 males and 67 females; mean age 29 ± 6.5 years) were included. Success rates for US- and FL-guided injections were 100%, while palpation-guided approach was significantly less successful (72%) (P = 0.02) with significantly more frequent extravasation (56%)(P < 0.001). US guidance was the least time-consuming (6.5 ± 1.6 min) compared to FL guidance (12.5 ± 1.9 min) and palpation guidance (8 ± 1.2 min) (all P < 0.001). The mean number of joint puncture attempts was significantly lower with imaging-guided techniques (1.1 ± 0.24 and 1.2 ± 0.4 for US and FL, P = 0.23) compared to palpation-guided one (1.6 ± 0.8) (P = 0.007). The largest increases in baseline-pain were 8-h post-injection, and US guidance was the least painful at all-time points (all P < 0.05). Joint distension and image quality were significantly better with imaging-guided techniques (P < 0.001 and P = 0.003).

CONCLUSIONS

US-guided radio-carpal injection is a less time-consuming, more tolerable, and successful radiation-free method when compared to FL guidance. Palpation-guided injections require multiple attempts to enter the joint with high failure rates and frequent extravasation.

Post-arthrogram synovitis: MRI and histopathologic findings

A 57-year-old patient developed severe, persistent pain following MR arthrography with iodinated contrast. MRI 1 week later showed synovitis which was new compared to the prior MRI. Arthroscopy showed severe synovitis. Histopathology showed synovitis characterized by lymphocytes, neutrophils, and necrosis. One out of 4 intraoperative cultures was positive, but ultimately believed to be due to contaminants. CRP normalized within 1 month. Repeat MRI 2 years later showed progressive degenerative findings, but no evidence of ongoing infection, or stigmata of previous infection. We believe this to be an unusually severe case of reactive synovitis. The purpose of the report is to add to knowledge of reactions to intra-articular contrast injection.

Does an elbow arthrogram change management after closed reduction of mildly displaced lateral condyle fractures in children?

The purpose of this study was to investigate whether an elbow arthrogram after closed reduction and percutaneous fixation of lateral condyle fractures results in a change in surgical management. This is a retrospective review of lateral condyle fractures managed with closed reduction and percutaneous fixation followed by an elbow arthrogram at our institution between 2008 and 2019. Chart and radiographic review was performed and operative notes were reviewed to determine rates of subsequent intervention after arthrogram. Descriptive statistics were used to summarize the data. This study included 47 patients. The majority of patients were male (34 patients, 72%), and the mean age at time of injury was 5.5 ± 2.6 years. The mean radiographic displacement was 2.6 mm (range 0.8-6.9 mm). All fractures were managed by fellowship-trained pediatric orthopaedic surgeons with an average of 10.5 years of experience (range 0-32 years). Fractures were stabilized with percutaneous pins in 44 patients (94%) and percutaneous screws in three patients (6%). No patients had subsequent changes in management after an elbow arthrogram. There were no complications related to performance of the arthrogram. Closed reduction and percutaneous fixation is often indicated for mildly displaced lateral condyle fractures. Articular reduction after percutaneous fixation is commonly assessed using an elbow arthrogram; however, it did not change surgical management in any case reviewed over the 10-year study period. While there seems to be little risk of performing an arthrogram, the clinical utility should be further evaluated.

Preoperative Evaluation and Surgical Simulation for Osteochondritis Dissecans of the Elbow Using Three-Dimensional MRI-CT Image Fusion Images

We used our novel three-dimensional magnetic resonance imaging-computed tomography fusion images (3D MRI-CT fusion images; MCFIs) for detailed preoperative lesion evaluation and surgical simulation in osteochondritis dissecans (OCD) of the elbow. Herein, we introduce our procedure and report the findings of the assessment of its utility. We enrolled 16 men (mean age: 14.0 years) and performed preoperative MRI using 7 kg axial traction with a 3-Tesla imager and CT. Three-dimensional-MRI models of the humerus and articular cartilage and a 3D-CT model of the humerus were constructed. We created MCFIs using both models. We validated the findings obtained from the MCFIs and intraoperative findings using the following items: articular cartilage fissures and defects, articular surface deformities, vertical and horizontal lesion diameters, the International Cartilage Repair Society (ICRS) classification, and surgical procedures. The MCFIs accurately reproduced the lesions and correctly matched the ICRS classification in 93.5% of cases. Surgery was performed as simulated in all cases. Preoperatively measured lesion diameters exhibited no significant differences compared to the intraoperative measurements. MCFIs were useful in the evaluation of OCD lesions and detailed preoperative surgical simulation through accurate reproduction of 3D structural details of the lesions.

Do Techniques for Hill-Sachs Remplissage Matter in Terms of Functional and Radiological Outcomes?

Background:

Different techniques are used for the remplissage procedure, including the double-pulley and mattress suture techniques. Both techniques have shown good results; however, it is unclear if one technique is superior.

Hypothesis:

The remplissage procedure using the double-pulley technique with 2 anchors would have superior functional and radiological outcomes compared with the mattress suture technique with a single anchor.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

This study included patients with anterior shoulder instability who were treated using arthroscopic Bankart repair combined with remplissage between 2012 and 2017. A structured questionnaire was used to gather information on the following metrics: Instability Severity Index Score, hyperlaxity, Sugaya index, presence of a Hill-Sachs defect, number of dislocations before surgery, sports participation, radiological measurement of the Hill-Sachs lesion, postoperative range of motion in both shoulders, Rowe score, Walch-Duplay score, American Shoulder and Elbow Surgeons score, and Filling Index Score of Remplissage grade according to magnetic resonance imaging scans at the last follow-up.

Results:

There were 41 patients included with a mean age of 30 ± 7 years who underwent the Hill-Sachs remplissage procedure using the double-pulley technique with 2 anchors (n = 21; group DA) or the mattress suture technique with a single anchor (n = 20; group SA). At the final follow-up, there were no significant differences between the groups regarding the Instability Severity Index Score (P = .134), the Sugaya index (P = .538), sports participation (P = .41), the radiological measurement of the Hill-Sachs lesion (P = .803), or the Rowe score (P = .182). However, there were significant differences between the groups in the Walch-Duplay score (P = .012), American Shoulder and Elbow Surgeons score (P = .005), and Filling Index Score of Remplissage grade (P = .015), favoring group DA, as well as differences in external rotation in a neutral position (external rotation loss: 9° ± 3° [group SA] vs 12° ± 3° [group DA]; P = .003) and at 90° of abduction (external rotation loss: 8° ± 3° [group SA] vs 11° ± 3° [group DA]; P = .006), favoring group SA.

Conclusion:

In the remplissage procedure, the double-pulley technique provided better filling of the lesion and improvement in functional scores, but external rotation was limited compared with the mattress suture technique.

Indirect Magnetic Resonance Arthrography May Help Avoid Second Look Arthroscopy for Assessment of Healing After Bucket Handle Medial Meniscus Repairs: A Prospective Clinico-Radiological Observational Study

OBJECTIVES

The objectives were: (1) to analyze the MRI healing rates of bucket-handle meniscus repair; (2) to compare the accuracy of assessment of meniscus healing for conventional MRI and Indirect Magnetic Resonance Arthrography (IMRA); and (3) to identify patients who may require second-look arthroscopy after meniscus repair.

METHODS

This is a prospective observational case series of thirty-seven patients with repaired bucket-handle medial meniscus tear with a minimum one year follow-up. Meniscus healing rates were assessed on direct MRI and IMRA using Henning's criteria. At the same time, patients' symptoms were evaluated according to Barrett's criteria and functional outcomes were recorded using International Knee Documentation Committee (IKDC) score, Knee Osteoarthritis and Outcomes Score (KOOS) and Tegner-Lysholm scores. A further clinical review was performed 18 months after the imaging to assess the evolution of symptoms.

RESULTS

At a mean of 22.3 ± 7.8 months after the meniscus repair, 56.7% patients showed complete healing and 40.5% patients demonstrated incomplete repair healing on IMRA. 52% patients with complete healing and 40% patients with incomplete healing demonstrated meniscus symptoms. At the second clinical review, 19% patients with complete healing and 20% patients with incomplete healing had meniscus symptoms. There was no co-relation between symptoms, PROMs and healing on MRI.

CONCLUSION

Indirect MR arthrography offers distinct advantages over direct MRI for assessment of meniscus healing, especially in symptomatic patients. Patient-reported outcome measures and symptomatology are not co-related with the healing status of the meniscus and they resolve in the majority on longer follow-up. A more conservative approach guided by IMRA to assess meniscus healing will avoid early re-operations.

Effect of elbow MRI with axial traction on articular cartilage visibility-a feasibility study

OBJECTIVE

Accurate evaluation of the articular cartilage of the elbow using MRI is sometimes challenging because of its anatomical complexity and relatively small size. Moreover, the articular cartilage of the humerus is in close contact with the opposing cartilage surfaces. Magnetic resonance arthrography with traction was reported to resolve this issue; however, less invasive methods are desirable. This study aimed to assess the effect of MRI with axial traction (without arthrography) on joint space widening and cartilage outline visibility of the elbow.

MATERIALS AND METHODS

We enrolled 10 volunteers (female = 1; mean age, 36.7 ± 8.6; range 28-56) and performed MRI with and without axial traction on the elbow. Joint space widths were measured, and the humeral articular cartilage outline visibility was evaluated at the radiocapitellar joint and lateral one-third and medial one-third of the ulnohumeral joints. Measurements were compared using the Wilcoxon signed-rank test. Significance was set at p < 0.05. Volunteers scored pain and discomfort during MRI with traction using the visual analog scale in a questionnaire format.

RESULTS

Traction significantly increased joint space width at the radiocapitellar joint. Humeral articular cartilage outline visibility also significantly improved at the radiocapitellar joint. Pain and discomfort scores during traction MRI were low.

CONCLUSION

MRI of the elbow with traction widens joint space and enables better articular cartilage visibility at the radiocapitellar joint. Anatomical features of the elbow might have affected these results. Therefore, it would be safe and useful for evaluating elbow injuries involving articular cartilage lesions.

Comparison between conventional MRI and MR arthrography in the diagnosis of triangular fibrocartilage tears and correlation with arthroscopic findings

PURPOSE

The triangular fibrocartilage complex is one of the most important stabilizers of the wrist and a defect in its anatomical structure is a possible cause of ulnar sided wrist pain. The aim of this study is to compare the diagnostic accuracy between conventional MRI and MR arthrography (MRA) in the depiction of triangular fibrocartilage complex (TFCC) tears.

METHODS-MATERIALS

A total of 60 patients with clinical findings that suggested TFCC tears underwent wrist MRI and MRA. All the MRI and MRA results were compared with the arthroscopic findings.

RESULTS

40 tears were confirmed by arthroscopy. 38/40 tears were identified by MRA while MRI identified 26/40 tears. There were also 8 false positives and 13 false negative results identified by MRI. Two false negative results were identified by MRA. No false positive results were identified.

CONCLUSION

MR arthrography is more sensitive and specific method in terms of the diagnosis of TFCC tears compared to conventional wrist MRI. There was no difference in the diagnostic accuracy between wrist arthroscopy and MRA.

How we do it: shifting MR arthrogram compounding from the fluoroscopy suite to the sterile pharmacy

OBJECTIVE

To assess the impact of shifting arthrogram injectate compounding from the fluoroscopy suite to the main hospital sterile pharmacy on cost, examination delays, and infection rates.

MATERIALS AND METHODS

All arthrograms from the 12 months before (629 in total) and the 12 months after (699 in total) the change in arthrogram preparation procedure were compared to identify differences in examination delays and infection rate. The arthrogram formulation was sent to the Compounder's International Analytical Laboratory for stability testing. Finally, cost per injection analysis was performed to compare fluoroscopy suite with sterile pharmacy compounding.

RESULTS

In the 699 arthrograms performed in the 12 months following transfer of arthrogram preparation to the main hospital pharmacy, there were 0 reported examination delays, 0 reported infections, and a 53% decrease in the material cost per arthrogram. There were three recorded instances of fluoroscopy suite preparation of arthrogram injectate due to unexpected add-on patients. Outside stability testing determined that the arthrogram injectate retained at least 90% potency 30 h post-preparation.

CONCLUSION

Shifting the compounding of the arthrogram injectate from the fluoroscopy room to the main hospital sterile pharmacy provides a modest cost saving and can be accomplished without examination delays or any increase in infection rate. It brought our practice into compliance with USP797, which is the current guideline for compounding practitioners, by transferring the compounding preparation of the arthrogram injectate from a procedure room to the sterile pharmacy.

Predictors of Pain and Discomfort Associated with CT Arthrography of the Shoulder

RATIONALE AND OBJECTIVES

The objective of this study was to investigate predictors of pain associated with computed tomographic arthrography of the shoulder.

MATERIALS AND METHODS

Before shoulder arthrography, all participants were assessed with the Hospital Anxiety and Depression Scale (HADS) and the World Health Organization Quality of Life Short Version Instrument (WHOQOL-BREF). The participants were nonrandomized into two groups: the anesthesia group, who underwent prior local infiltration anesthesia before shoulder arthrography, and the nonanesthesia group, who did not undergo prior local infiltration anesthesia. The pain levels at intraprocedure, at 1, 2, 6, and 12 hours, and at 1 and 2 days after injection were assessed by using a visual analog scale. Univariate and multivariate generalized linear model analyses were conducted.

RESULTS

Sixty participants in the anesthesia group and 60 participants in the nonanesthesia group were included. The pain level at intraprocedure (3.37 ± 1.94 in the anesthesia group and 3.20 ± 1.34 in the nonanesthesia group) was the highest of the whole pain course. The psychological domain (P = .0013) of WHOQOL-BREF, gender (P = .042), body mass index (P = .0001), and the total number of reinsertion and redirection of needle (P< .0001) were independent predictors of arthrography-related pain.

CONCLUSIONS

The pain associated with shoulder computed tomographic arthrography depends on the psychological domain of WHOQOL-BREF, gender, body mass index, and the total number of reinsertion and redirection of needle.

Magnetic resonance arthrography of the shoulder: a painful procedure?

Objective

To compare the pain expected to that effectively caused by magnetic resonance arthrography of the shoulder and, secondarily, to describe a simplified approach to the technique for articular access.

Materials and Methods

We prospectively evaluated 40 participants who used a visual analog scale and a simplified categorical scale to indicate the level of pain expected and that experienced after the procedure, comparing the two with the Wilcoxon matched-pairs test. We also determined gender-related differences in pain conditions using the Mann-Whitney U test. In addition, we described a modified technique involving radiographic localization and the use of standard puncture needles for articular access.

Results

Analysis of the visual analog scales showed that the pain experienced was less than had been expected, with median scores of 1.75 and 3.75, respectively (p < 0.001). The level of pain expected was higher among women than among men, with median scores of 8.0 and 3.0, respectively (p = 0.014), as was the level of pain experienced, with median scores of 3.0 and 1.5, respectively (p = 0.139). The overall categorical evaluation corroborated that difference (p = 0.03). Articular access with the modified technique was successful in all patients.

Conclusion

Magnetic resonance arthrography of the shoulder is less painful than patients expect. In addition, digital radiographic guidance combined with the use of standard puncture needles appears to improve the efficiency of the method.

Preoperative planning for redirective, periacetabular osteotomies

Redirective, periacetabular osteotomies (PAO) represent a group of surgical procedures for treatment of developmental dysplasia of the hip (DDH) in skeletally mature and immature patients. The ultimate goal of all procedures is to reduce symptoms, improve function and delay or prevent progression of osteoarthritis. During the last two decades, the understanding of the underlying pathomechanisms has continuously evolved. This is mainly attributable to the development of the femoroacetabular impingement concept that has increased the awareness of the underlying three-dimensional complexity associated with DDH. With increasing knowledge about the pathobiomechanics of dysplastic hips, diagnostic tools have improved allowing for sophisticated preoperative analyses of the morphological and pathobiomechanical features, and early recognition of degenerative changes, which may alter the long-term outcome. As redirective, PAO are technically demanding procedures, preoperative planning is crucial to avoid intraoperative obstacles and to sufficiently address the patient-specific deformity. Although conventional radiography has been used for decades, it has not lost its primary role in the diagnostic work-up of patients with DDH. Furthermore, an increasing number of modern imaging techniques exists allowing for assessment of early cartilage degeneration (biochemical magnetic resonance imaging) as well as 3D planning and computer-based virtual treatment simulation of PAO. This article reviews the literature with regard to the current concepts of imaging of DDH, preoperative planning and treatment recommendations for redirective, PAO.

A prospective randomized study comparing three different approaches to fluoroscopy-guided shoulder arthrography according to the experience of practitioners

OBJECTIVE

To compare three approaches via the anterior and posterior glenohumeral joints, and the rotator interval in fluoroscopy-guided shoulder arthrography according to the experience of the practitioners.

MATERIALS AND METHODS

This prospective randomized study was originally designed to have 34 subjects for each approach, and finally evaluated 98 patients (mean age: 51.5 years; 55 men) from July to December 2014, who had shoulder arthrography via the anterior (n = 41) or posterior glenohumeral joint (n = 27) approaches, or via the rotator interval approach (n = 30) by residents (n=76) or fellows (n=22). The success rate, number of punctures, fluoroscopy time, radiation dose, and complications of the three methods were compared, and according to the practitioners.

RESULTS

The success rate was 100% for the anterior glenohumeral joint approach (34 out of 34), 90.0% for the posterior glenohumeral joint approach (23 out of 30), and 88.2% for the rotator interval approach (30 out of 34; p = 0.013). There was no difference in the success rate according to the practitioners' experience. Fluoroscopy time was longest for the posterior glenohumeral joint approach (mean: 95.44 s) and shortest for the rotator interval approach (mean: 31.57 s, p = 0.006). Radiation dose was larger by 1st- or 2nd-year residents (p = 0.014), with no difference among the three approaches. Only one patient who underwent arthrography using the posterior glenohumeral joint approach complained about post-procedural pain.

CONCLUSION

Fluoroscopy-guided shoulder arthrography via the posterior glenohumeral joint or rotator interval approach may be difficult for trainees, and the posterior glenohumeral joint approach may need a long fluoroscopy time.

Iopromide- and gadopentetic acid-derived preparates used in MR arthrography may be harmful to chondrocytes

Background

Magnetic resonance arthrography, a procedure through which contrast agents containing gadolinium and/or iopromide are administered intra-articularly, has become a useful tool in musculoskeletal diagnosis. Nevertheless, despite being considered safe for systemic use, certain tissue toxicities have been identified for both drugs. In this study, the effects of short-term exposure of human primary chondrocyte cell cultures to gadolinium and/or iopromide contrast agents were examined by assaying for stage-specific embryonic antigen-1 (SSEA-1) protein expression (a chondrogenic differentiation marker), cell viability, toxicity, and proliferation.

Methods

Human articular chondrocytes were grown in monolayer culture and were exposed to iopromide and/or gadolinium diethylenetriamine-pentaacetate (Gd-DPT) for 2 and 6 h. Cell cultures with no drug exposure were used as the control group. Cell differentiation status was assessed according to SSEA-1 protein expression. Contrast agent effects on cell viability and proliferation were analyzed using MTT analysis. Further, changes in cell morphology in relation to the control group were evaluated using inverted light microscopy, environmental scanning electron microscopy (ESEM), and 3-tesla magnetic resonance imaging. The obtained data were statistically compared.

Results

When compared with the control group, both SSEA-1 protein expression and cell proliferation were lowest in the Gd-DPT group (P = 0.000). There was a statistically significant correlation between SSEA-1 expression and MTT results (rho = 0.351; P = 0.003).

Conclusions

Nevertheless, the data obtained from in vitro experiments may not directly correspond to clinical applications. However, the mere fact that a drug used solely for diagnostic purposes may repress chondrocyte cell proliferation should be carefully considered by clinicians.

3D double-echo steady-state sequence assessment of hip joint cartilage and labrum at 3 Tesla: comparative analysis of magnetic resonance imaging and intraoperative data

OBJECTIVES

To assess the diagnostic accuracy of a high-resolution, three-dimensional (3D) double-echo steady-state (DESS) sequence with radial imaging at 3 Tesla (T) for evaluating cartilage and labral alterations in the hip.

METHODS

Magnetic resonance imaging (MRI) data obtained at 3 T, including radially reformatted DESS images and intraoperative data of 45 patients (mean age 42 ± 13.7 years) who underwent hip arthroscopy, were compared. The acetabular cartilage and labrum of the upper hemisphere of the acetabulum and the central femoral head cartilage were evaluated. Sensitivity, specificity, accuracy, and negative and positive predictive values were determined.

RESULTS

Sensitivity, specificity and accuracy of the DESS technique were 96.7%, 75% and 93.7% for detecting cartilage lesions and 98%, 76.2% and 95.9% for detecting labral lesions. The positive and negative predictive values for detecting or ruling out cartilage lesions were 96% and 78.9%. For labral lesions, the positive and negative predictive values were 97.5% and 80%.

CONCLUSION

A high-resolution, 3D DESS technique with radial imaging at 3 T demonstrated high accuracy for detecting hip cartilage and labral lesions with excellent interobserver agreement and moderate correlation between MRI and intraoperative assessment.

KEY POINTS

• High-resolution, 3D DESS with radial imaging allows accurate cartilage and labrum evaluation. • DESS demonstrated high sensitivity, specificity, accuracy for detecting cartilage and labral lesions. • Highly accurate sequence may influence treatment decisions in patients with hip pain.

Distinct Proximal Humeral Geometry in Chinese Population and Clinical Relevance

BACKGROUND

Replicating humeral anatomy during shoulder arthroplasty is important for good patient outcomes. The proximal humeral geometry of the Chinese population has been rarely reported. We analyzed the geometry of the proximal part of the humerus in Chinese subjects and compared it with that of Western populations and the dimensions of available prostheses.

METHODS

Eighty healthy Chinese subjects underwent computed tomography (CT)-arthrography. Three-dimensional (3D) digital humeral and glenoid models were reconstructed, and geometric parameters were measured. Humeral measurements included the radius of curvature, articular surface diameter and thickness, anterior-posterior/superior-inferior (AP/SI) articular surface diameter ratio, articular surface thickness/radius of curvature ratio, surface arc, inclination angle, retroversion angle, and medial and posterior offsets. Glenoid measurements included SI length, AP length, SI radius, and AP radius.

RESULTS

The average radius of curvature (and standard deviation) of the humeral head was 22.1 ± 1.9 mm, the articular surface diameter averaged 42.9 ± 3.6 mm, and the articular surface thickness averaged 16.9 ± 1.5 mm. There was strong linear correlation between the articular surface diameter and thickness (r = 0.696, p = 0.001), with a linear regression relationship of thickness = 0.357 × diameter + 1.615. The AP/SI articular surface diameter ratio averaged 0.93 ± 0.03; the articular surface thickness/radius of curvature ratio, 0.77 ± 0.05; the surface arc, 153° ± 5.6°; the inclination angle, 133° ± 3.1°; and the retroversion angle, 22.6° ± 10.2°. The medial and posterior offsets averaged 6.3 ± 0.9 mm and 0.4 ± 0.78 mm, respectively; the SI and AP lengths, 30.15 ± 3.70 mm and 20.35 ± 2.56 mm; and the SI and AP radii, 23.49 ± 2.48 mm and 25.54 ± 3.07 mm. Compared with the Western population, the Chinese cohort had a smaller radius of curvature (p < 0.001), smaller articular surface diameter (p = 0.009), larger articular surface thickness/radius of curvature ratio (p < 0.001), larger surface arc (p < 0.001), smaller inclination angle (p < 0.001), and smaller posterior offset (p < 0.001). Unlike the Western population, the Chinese population had higher glenohumeral conformity in the coronal plane than in the axial plane. Many manufacturers' shoulder prostheses do not adequately cover the range of humeral head dimensions in our Chinese cohort.

CONCLUSIONS

The geometric parameters of the humeri in the Chinese population differ from those in other populations. These differences have clinical relevance with regard to implant design and arthroplasty technique and likely affect clinical outcomes.

Detour sign in the diagnosis of subluxation of the long head of the biceps tendon with arthroscopic correlation

OBJECTIVE

To determine whether detection of the detour sign via MRI indicates subluxation of the long head of the biceps tendon (SLBT) in the shoulder joint and to investigate the association of SLBT with the degeneration of the long head of the biceps tendon (LBT) and rotator cuff tears.

METHODS

This retrospective study included 65 patients with shoulder pain who underwent shoulder MRI and arthroscopic surgery. When axial images revealed that the LBT was displaced over the inner rim of the bicipital groove with some remaining contact with the groove (Criterion 1), or demonstrated a "detour sign" of the biceps tendon (Criterion 2), the lesion was diagnosed as an SLBT. Shoulder arthroscopy was used as the reference standard.

RESULTS

Arthroscopy identified SLBT in 18 patients. When the MRI diagnosis was based on Criterion 1 alone, SLBT was diagnosed with a sensitivity of 44.4-55.6% and 75.4-80% accuracy. However, when the MRI diagnosis was based on Criteria 1 plus 2, SLBT was diagnosed with a sensitivity of 83.3-94.4% and 78.5-81.5% accuracy. There was a significant difference (p < 0.05) in the diagnostic sensitivity of Criteria 1 and 2.

CONCLUSION

The detour sign based on axial MRI may be regarded an additional useful anatomical feature that improves the diagnostic performance of MRI in the identification of SLBT lesions. Advances in knowledge: Recognition of the detour sign may enhance the diagnostic performance of the conventional MRI protocol over the MR arthrography protocol for SLBT.

Quantitative diffusion-weighted magnetic resonance imaging for the diagnosis of partial-thickness rotator cuff tears

BACKGROUND

This study investigated diffusion-weighted (DWI) magnetic resonance imaging (MRI) as an alternative to fat-suppressed T2-weighted imaging (FS-T2WI) for assessment of partial-thickness rotator cuff tears (RCTs).

METHODS

Patients with arthroscopy proven partial-thickness RCTs who also received MRI (FS-T2WI and DWI) before surgery were prospectively included. Receiver operating characteristic curves were used to compare DWI vs. FS-T2WI using lesion-to-muscle signal intensity ratios. A cutoff point for predicting partial-thickness tears was determined using the Youden index.

RESULTS

Included were 146 patients, with a mean age of 48.3 years (range, 19-86 years), of whom 43 had full-thickness RCTs, 67 had partial-thickness RCTs, and 36 had no tears. Areas under receiver operating characteristic curves for diagnosing partial-thickness tears were significantly higher for DWI (0.910) than for FS-T2WI (0.822, P = .016). Lesion-to-muscle signal intensity ratio cutoff values were 1.06 for DWI vs. 1.65 for FS-T2WI, respectively. The sensitivity and accuracy of DWI (89.1% [98 of 110] and 87.7% [128 of 146], respectively) for diagnosing partial-thickness and full-thickness tears were higher than for FS-T2WI (65.5% [72 of 110] and 72.6% [106 of 146], respectively). FS-T2WI, however, had higher specificity (94.4% [34 of 36]) than DWI (83.3% [30 of 36]).

CONCLUSIONS

DWI is more accurate and sensitive than FS-T2WI for diagnosing partial-thickness RCTs.

Pathomechanics and Magnetic Resonance Imaging of the Thrower's Shoulder

Repetitive, high-velocity overhead throwing can lead to several adaptive changes in the throwing shoulder, which over time lead to structural microtrauma and eventually overt injury. MR imaging is a useful imaging modality to evaluate these changes and to characterize their acuity and severity. Understanding the throwing motion and the effects of this motion on the structures of the shoulder can help radiologists to recognize these findings and provide useful information to referring physicians, which may affect the treatment of these athletes. This article reviews shoulder pathomechanics and MR imaging findings in overhead throwing athletes.

Magnetic Resonance Arthrography of the Wrist and Elbow

Magnetic resonance (MR) arthrography of the wrist and elbow is useful for detecting a variety of intra-articular pathologies. MR dictations should address whether intrinsic ligament tears of the wrist are partial-thickness or full-thickness, and involve the dorsal, membranous, and/or volar components of the ligaments. With regard to elbow soft tissue pathology, partial-thickness tears of the anterior band of the ulnar collateral ligament in overhead-throwing athletes are well evaluated with MR arthrography. MR arthrography also is helpful in staging osteochondritis dissecans of the capitellum, caused by repetitive valgus impaction injury in adolescent or young adult baseball pitchers.

MRI for the preoperative evaluation of femoroacetabular impingement

Femoroacetabular impingement (FAI) refers to a condition characterized by impingement of the femoral head–neck junction against the acetabular rim, often due to underlying osseous and/or soft tissue morphological abnormalities. It is a common cause of hip pain and limited range of motion in young and middle-aged adults. Hip preservation surgery aims to correct the morphological variants seen in FAI, thereby relieving pain and improving function, and potentially preventing early osteoarthritis. The purpose of this article is to review the mechanisms of chondral and labral injury in FAI to facilitate an understanding of patterns of chondrolabral injury seen on MRI. Preoperative MRI evaluation of FAI should include assessment of osseous morphologic abnormalities, labral tears, cartilage status, and other associated compensatory injuries of the pelvis. As advanced chondral wear is the major relative contraindication for hip preservation surgery, MRI is useful in the selection of patients likely to benefit from surgery.

Teaching points

• The most common anatomical osseous abnormalities predisposing to FAI include cam and pincer lesions.

• Morphological abnormalities, labral lesions, and cartilage status should be assessed.

• In cam impingement, chondral wear most commonly occurs anterosuperiorly.

• Pre-existing advanced osteoarthritis is the strongest predictor of poor outcomes after FAI surgery.

• Injury to muscles and tendons or other pelvic structures can coexist with FAI.

Interventional articular and para-articular knee procedures

The knee is a common area of the body to undergo interventional procedures. This article discusses image-guided interventional issues specific to the knee area. The soft tissues in and around the knee are frequently affected by sport-related injuries and often need image-guided intervention. This article details the specific technical issues related to intervention in these soft tissues, including the iliotibial tract, fat pads, patellar tendon and other tendons, bursae and the meniscus. Most often, simple procedures such as injection and aspiration are performed without image guidance. Rarely image-guided diagnostic arthrography and therapeutic joint injections are necessary. The technique, indications and diagnostic considerations for arthrography are discussed in this article. Primary bone and soft-tissue tumours may involve the knee and adjacent soft tissues. Image-guided biopsies are frequently necessary for these lesions; this article details the technical issues related to image-guided biopsy around the knee. A number of newer ablation treatments are now available, including cryoablation, high-frequency ultrasound and microwave ablation. Radiofrequency ablation, however, still remains the most commonly employed ablation technique. The indications, technical and therapeutic considerations related to the application of this technique around the knee are discussed here. Finally, we briefly discuss some newer, but as of yet, unproven image-guided interventions for osteochondral lesions and Brodie's abscess.

Secondary frozen shoulder following septic arthritis - An unusual complication of magnetic resonance arthrogram

INTRODUCTION

Magnetic resonance (MR) arthrogram is a commonly used investigation tool to detect various pathologies in the shoulder. The complications following this procedure is minor and rare. Septic arthritis is one of the rare complications which can develop after MR arthrogram. We report a case of secondary frozen shoulder after MR arthrogram induced septic arthritis.

PRESENTATION OF CASE

A young, fit and well female patient underwent MR arthrogram to detect any labral tears. Two days following the procedure, she developed signs and symptoms suggestive of septic arthritis of the shoulder. The patient underwent repeated arthroscopic debridement and washout. The organisms isolated was Staphylococcus epidermidis. She was treated with six weeks of intravenous antibiotics. The patient developed stiffness of the shoulder due to secondary frozen shoulder which was treated with arthroscopic capsular release with good functional outcomes at three months.

DISCUSSION

MR arthrogram is a rare cause of septic arthritis of the shoulder. The common method introducing the organisms is from the skin flora or contaminated arthrogram trays. The treatment is repeated arthroscopic washouts and six weeks of appropriate intravenous antibiotics. Residual pain, stiffness and chondrolysis are common sequelae of septic arthritis.

CONCLUSION

Septic arthritis is a recognised and rare complication of MR arthrogram. Early and prompt diagnosis with arthroscopic washout and debridement combined with intravenous antibiotics helps to eradicate the infection. Secondary frozen shoulder is a late complication of sepsis in the joint.

Diagnostic performance of direct traction MR arthrography of the hip: detection of chondral and labral lesions with arthroscopic comparison

OBJECTIVES

To assess diagnostic performance of traction MR arthrography of the hip in detection and grading of chondral and labral lesions with arthroscopic comparison.

METHODS

Seventy-five MR arthrograms obtained ± traction of 73 consecutive patients (mean age, 34.5 years; range, 14-54 years) who underwent arthroscopy were included. Traction technique included weight-adapted traction (15-23 kg), a supporting plate for the contralateral leg, and intra-articular injection of 18-27 ml (local anaesthetic and contrast agent). Patients reported on neuropraxia and on pain. Two blinded readers independently assessed femoroacetabular cartilage and labrum lesions which were correlated with arthroscopy. Interobserver agreement was calculated using κ values. Joint distraction ± traction was evaluated in consensus.

RESULTS

No procedure had to be stopped. There were no cases of neuropraxia. Accuracy for detection of labral lesions was 92 %/93 %, 91 %/83 % for acetabular lesions, and 92 %/88 % for femoral cartilage lesions for reader 1/reader 2, respectively. Interobserver agreement was moderate (κ = 0.58) for grading of labrum lesions and substantial (κ = 0.7, κ = 0.68) for grading of acetabular and femoral cartilage lesions. Joint distraction was achieved in 72/75 and 14/75 hips with/without traction, respectively.

CONCLUSION

Traction MR arthrography safely enabled accurate detection and grading of labral and chondral lesions.

KEY POINTS

• The used traction technique was well tolerated by most patients. • The used traction technique almost consistently achieved separation of cartilage layers. • Traction MR arthrography enabled accurate detection of chondral and labral lesions.

Postprocedural pain in shoulder arthrography: differences between using preservative-free normal saline and normal saline with benzyl alcohol as an intraarticular contrast diluent

OBJECTIVE

The purpose of this study was to prospectively evaluate the effect of benzyl alcohol, a common preservative in normal saline, on postprocedural pain after intraarticular injection for direct shoulder MR arthrography.

SUBJECTS AND METHODS

From April 2011 through January 2013, 138 patients underwent direct shoulder MR arthrography. Using the Wong-Baker Faces Pain Scale, patients were asked to report their shoulder pain level immediately before and immediately after the procedure and then were contacted by telephone 6, 24, and 48 hours after the procedure. Fourteen patients did not receive the prescribed amount of contrast agent for diagnostic reasons or did not complete follow-up. Sixty-two patients received an intraarticular solution including preservative-free normal saline (control group) and 62 patients received an intraarticular solution including normal saline with 0.9% benzyl alcohol as a contrast diluent (test group). Patients were randomized as to which intraarticular diluent they received. Fluoroscopic and MR images were reviewed for extracapsular contrast agent administration or extravasation, full-thickness rotator cuff tears, and adhesive capsulitis. The effect of preservative versus control on pain level was estimated with multiple regression, which included time after procedure as the covariate and accounted for repeated measures over patients.

RESULTS

Pain scale scores were significantly (p = 0.0382) higher (0.79 units; 95% CI, 0.034-1.154) with benzyl alcohol preservative compared with control (saline). In both study arms, the pain scale scores decreased slightly after the procedure, increased by roughly 1 unit over baseline for the test group and 0.3 unit over baseline for the control group by 6 hours after the procedure, were 0.50 unit over baseline for the test group and 0.12 unit over baseline for the control group at 24 hours, then fell to be slightly greater than baseline at 48 hours with benzyl alcohol and slightly less than baseline without benzyl alcohol. These trends over time were highly significant (p < 0.0001).

CONCLUSION

Shoulder arthrography is often associated with postprocedural discomfort that begins immediately after the procedure and resolves by 48 hours. There is significantly increased patient discomfort at 6 and 48 hours when using normal saline preserved with benzyl alcohol as a diluent compared with using normal saline without preservative as a diluent.

Improving visualization of the central compartment of the hip with direct MR arthrography under axial leg traction: a feasibility study

RATIONALE AND OBJECTIVES

To evaluate the feasibility of a modified approach for direct magnetic resonance (MR) arthrography of the hip under leg traction in achieving a sufficient femoroacetabular interface and improving the visualization of the ligamentum teres.

MATERIALS AND METHODS

Forty-six MR arthrograms of 44 patients who underwent MR arthrography with and without leg traction were included into the study. Traction approach included injection of 18-27 mL of fluid (local anesthetic, contrast agent), application of weight-adapted traction load (15-23 kg), and the use of a supporting plate. Patients were instructed to report on pain and complications with an integer pain scale. Joint distraction was measured on coronal images obtained with and without traction, and two radiologists independently evaluated whether femoroacetabular cartilage layers and the ligamentum teres could be seen as distinct entities. McNemar test was used and interobserver agreement was assessed.

RESULTS

No patient asked for termination of the examination. There were no cases of neuropraxia. Mean difference in distraction was 3.7 mm/3.6 mm (reader 1/reader 2). Cartilage layers could be seen as distinct entities in 43/43 (93.5%/93.5%) and 6/8 (13%/17.4%) of the joints with/without traction (P < .001/P < .001), respectively. The ligamentum teres could be differentiated in 33/30 (71.7%/65.2%) cases with traction, in 33/30 (71.7%/65.2%) cases without traction (P < .999/P < .999), and in 40/37 (87%/80.4%) cases with both the techniques combined.

CONCLUSIONS

Traction MR arthrography is safe and technically feasible. It enabled the differentiation between femoroacetabular cartilage layers in most cases. Visualization of the ligamentum teres was optimal by combining imaging with both modalities.

MRI of the hip for the evaluation of femoroacetabular impingement; past, present, and future

The concept of femoroacetabular impingement (FAI) has, in a relatively short time, come to the forefront of orthopedic imaging. In just a few short years MRI findings that were in the past ascribed to degenerative change, normal variation, or other pathologies must now be described and included in radiology reports, as they have been shown, or are suspected to be related to, FAI. Crucial questions have come up in this time, including: what is the relationship of bony morphology to subsequent cartilage and labral damage, and most importantly, how is this morphology related to the development of osteoarthritis? In this review, we attempt to place a historical perspective on the controversy, provide guidelines for interpretation of MRI examinations of patients with suspected FAI, and offer a glimpse into the future of MRI of this complex condition.

Preoperative diagnosis of pathologic conditions of the ligamentum teres: is MRI a valuable imaging modality?

PURPOSE

The purpose of this study was to determine the accuracy of 3-Tesla magnetic resonance imaging (MRI) in detecting ligamentum teres (LT) lesions in patients before they undergo hip arthroscopy for the treatment of femoroacetabular impingement.

METHODS

From 2010 to 2011, data were prospectively collected on all patients presenting for treatment of hip pain. All patients underwent MRI followed by arthroscopic surgery. A radiologist prospectively documented MRI findings, and the surgeon recorded the findings at arthroscopy. Radiologic and surgical data included classification of the LT as not torn, hypertrophic, partially torn, or completely torn. All MR images were read by a single radiologist, and all surgery was performed by a single surgeon. Arthroscopy was considered the diagnostic gold standard.

RESULTS

One hundred forty-two patients with a mean patient age of 35 years (range, 19 to 73 years) met the inclusion criteria. Only one complete LT tear was found in the study. The accuracy of MRI for the diagnosis of LT partial tears was 64%. The sensitivity and specificity of MRI for diagnosing partial tears of the LT were 9% and 91%, [corrected] respectively. The positive predictive value and negative predictive value were 31% and 67%, [corrected] respectively. The sensitivity and specificity of MRI for diagnosing hypertrophic LT were 32% and 78%, respectively.

CONCLUSIONS

In this patient population, MRI demonstrated sensitivity and specificity of 34% and 50%, [corrected] respectively, in identifying any pathologic process of the LT. MRI is capable of ruling out [corrected] partial tears of the LT with high sensitivity (91%) and negative [corrected] predictive value (67%).

LEVEL OF EVIDENCE

Level II, development of diagnostic criteria on basis of consecutive patients with universally applied gold standard.

Clinics in diagnostic imaging. 148. Bursal-sided partial-thickness supraspinatus tendon tear

Rotator cuff injury comprises a continual spectrum of lesions ranging from tendinopathy, which may progress to partial- or full-thickness tear. This progression may be influenced by the interplay of extrinsic and intrinsic factors. We describe the case of a 29-year-man who presented with right shoulder pain for one year. His initial magnetic resonance (MR) arthrogram showed supraspinatus tendinopathy. Subsequent MR arthrogram, obtained after a road traffic accident, showed a bursal-sided partial-thickness tear of the supraspinatus tendon. In view of his worsening clinical symptoms, surgery was performed ten months later, revealing a full-thickness rotator cuff tear near the tendon insertion, with a tight subacromial space and bony protuberance of the humeral head. The pathogenesis of rotator cuff injuries, the roles of different imaging modalities in the diagnosis of rotator cuff injuries, as well as the advantages and limitations of various radiological modalities, are discussed.

Outbreak of joint infections associated with magnetic resonance arthrograms performed at an outpatient radiology center

An outbreak of methicillin-susceptible Staphylococcus aureus joint infections occurred at an outpatient radiology center. We identified 7 case patients; all had undergone magnetic resonance arthrograms with intra-articular joint injections. The outbreak was likely due to unsafe injection practices in preparation of contrast solution for intra-articular injection.