MRI of Labral and Chondral Lesions of the Hip

The Association Between the Development of Cam Morphology During Skeletal Growth in High-Impact Athletes and the Presence of Cartilage Loss and Labral Damage in Adulthood: A Prospective Cohort Study With a 12-Year Follow-up

BACKGROUND

Cam morphology develops during skeletal growth, but its influence on cartilage and the labrum in high-impact athletes later in life is unknown.

PURPOSE

To (1) explore the association between the presence and duration of cam morphology during adolescence and the cartilage and labral status 7 to 12 years later and (2) report the prevalence of cartilage loss and labral damage in a population of young male athletes (<32 years old) who played professional soccer during skeletal growth.

STUDY DESIGN

Cohort study (Prognosis); Level of evidence, 2.

METHODS

A total of 89 healthy male academy soccer players from the Dutch soccer club Feyenoord (aged 12-19 years) were included at baseline. At baseline and 2.5- and 5-year follow-ups, standardized supine anteroposterior pelvis and frog-leg lateral radiographs of each hip were obtained. At 12-year follow-up, magnetic resonance imaging of both hips was performed. Cam morphology was defined by a validated alpha angle ≥60° on radiographs at baseline or 2.5- or 5-year follow-up when the growth plates were closed. Hips with the presence of cam morphology at baseline or at 2.5-year follow-up were classified as having a "longer duration" of cam morphology. Hips with cam morphology only present since 5-year follow-up were classified as having a "shorter duration" of cam morphology. At 12-year follow-up, cartilage loss and labral abnormalities were assessed semiquantitatively. Associations were estimated using logistic regression, adjusted for age and body mass index.

RESULTS

Overall, 35 patients (70 hips) with a mean age of 28.0 ± 2.0 years and mean body mass index of 24.1 ± 1.8 participated at 12-year follow-up. Cam morphology was present in 56 of 70 hips (80%). The prevalence of cartilage loss was 52% in hips with cam morphology and 21% in hips without cam morphology (adjusted odds ratio, 4.52 [95% CI, 1.16-17.61]; P = .03). A labral abnormality was present in 77% of hips with cam morphology and in 64% of hips without cam morphology (adjusted odds ratio, 1.99 [95% CI, 0.59-6.73]; P = .27). The duration of cam morphology did not influence these associations.

CONCLUSION

The development of cam morphology during skeletal growth was associated with future magnetic resonance imaging findings consistent with cartilage loss in young adults but not with labral abnormalities.

Comparison of MRI and arthroscopy findings for transitional zone cartilage damage in the acetabulum of the hip joint

OBJECTIVE

To assess the performance of morphologic and hypointense signal changes on MRI to predict grades and types of acetabular cartilage damage in the chondrolabral transitional zone (TZ) of the hip identified at arthroscopy.

MATERIALS AND METHODS

This retrospective single-center study reviewed conventional 3T MRI hip studies from individuals with symptomatic femoroacetabular impingement (FAI) and subsequent hip arthroscopy surgery within 6 months. Independent review was made by three radiologists for the presence of morphologic damage or a hypointense signal lesion in the TZ on MRI. Fleiss' kappa statistic was used to assess inter-reader agreement. The degree of TZ surfacing damage (modified Outerbridge grades 1-4) and presence of non-surfacing wave sign at arthroscopic surgery were collected. Relationship between sensitivity and lesion grade was examined.

RESULTS

One hundred thirty-six MRI hip studies from 40 males and 74 females were included (mean age 28.5 years, age range 13-54 years). MRI morphologic lesions had a sensitivity of 64.9-71.6% and specificity of 48.4-67.7% for arthroscopic surfacing lesions, with greater sensitivity seen for higher grade lesions. Low sensitivity was seen for wave sign lesions (34.5-51.7%). MRI hypointense signal lesions had a sensitivity of 26.3-62% and specificity of 43.8-78.0% for any lesion. Inter-reader agreement was moderate for morphologic lesions (k = 0.601) and poor for hypointense signal lesions (k = 0.097).

CONCLUSION

Morphologic cartilage damage in the TZ on MRI had moderate sensitivity for any cartilage lesion, better sensitivity for higher grade lesions, and poor sensitivity for wave sign lesions. The diagnostic value of hypointense signal lesions was uncertain.

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.

The Role of MRI in Groin Pain Syndrome in Athletes

Groin pain syndrome (GPS) is one of the most frequent injuries in competitive sports. Stresses generated in the lower limbs by quick turns and accelerations, such as in soccer, basketball or hockey, can produce localized regions of increased forces, resulting in anatomical lesions. The differential diagnoses are numerous and comprise articular, extra-articular, muscular, tendinous and visceral clinical conditions and a correct diagnosis is crucial if treatment is to be efficient. MRI is the gold standard of diagnostic techniques, especially when an alternative pathology needs to be excluded and/or other imaging techniques such as ultrasound or radiography do not lead to a diagnosis. This paper, based on the current literature, gives a comprehensive review of the anatomy of the pubic region and of the typical MRI findings in those affected by GPS. Many clinical conditions causing GPS can be investigated by MRI within appropriate protocols. However, MRI shows limits in reliability in the investigation of inguinal and femoral hernias and therefore is not the imaging technique of choice for studying these clinical conditions.

No Difference in Patient-Reported Outcomes for Periacetabular Osteotomy and Hip Arthroscopy With Capsular Plication in the Setting of Borderline Hip Dysplasia: A Propensity-Matched Multicenter Study With Minimum 5-Year Follow-Up

PURPOSE

To compare minimum 5-year patient-reported outcome measures after hip arthroscopy (HA) and periacetabular osteotomy (PAO) for borderline hip dysplasia.

METHODS

Hips with a lateral center-edge angle (LCEA) between 18° and less than 25° that underwent either PAO or HA were selected from 2 institutions. The exclusion criteria were as follows: LCEA less than 18°, Tönnis osteoarthritis grade greater than 1, prior hip surgical procedures, active inflammatory disease, Workers' Compensation, and concomitant surgery. Patients underwent propensity matching based on age, sex, body mass index, and Tönnis osteoarthritis grade. Patient-reported outcome measures included the modified Harris Hip Score, as well as calculation of the minimal clinically important difference, patient acceptable symptom state, and maximum outcome improvement satisfaction threshold. Preoperative radiographic predictors included comparison of the Femoro-epiphyseal Acetabular Roof index and ligamentum teres lesions.

RESULTS

A total of 28 PAO patients underwent propensity matching to 49 HA patients. The 2 groups were similar in terms of mean age, sex, preoperative body mass index, and LCEA. The PAO group had a longer mean follow-up period (95.8 months vs 81.3 months, P = .001). The mean Femoro-epiphyseal Acetabular Roof index was significantly lower preoperatively in the HA group (P < .001). The 2 groups showed similar and significant improvements in the mean modified Harris Hip Score from preoperatively to latest follow-up (P < .001). The relative risk of subsequent surgery in the PAO group was 3.49 (P = .024), mostly attributed to hardware removal (25%). The revision rate was 3.6% in the PAO group and 8.2% in the HA group (P = .65). One patient in the PAO group required revision HA for intra-articular adhesions. Three of the patients requiring revision in the HA group underwent PAO because of persistent pain, and one underwent revision HA alone. Conversion to total hip arthroplasty was required in 1 patient in the HA group and no patients in the PAO group.

CONCLUSIONS

Both PAO and HA with capsular plication provide borderline hip dysplasia patients with clinically significant improvements and low revision rates at a minimum of 5 years postoperatively.

LEVEL OF EVIDENCE

Level III, retrospective, comparative therapeutic trial.

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.

Factors influencing patient-reported outcomes following periacetabular osteotomy and open osteochondroplasty in the setting of borderline hip dysplasia

Aims

This study reports mid-term outcomes after periacetabular osteotomy (PAO) exclusively in a borderline hip dysplasia (BHD) population to provide a contrast to published outcomes for arthroscopic surgery of the hip in BHD.

Methods

We identified 42 hips in 40 patients treated between January 2009 and January 2016 with BHD defined as a lateral centre-edge angle (LCEA) of ≥ 18° but < 25°. A minimum five-year follow-up was available. Patient-reported outcomes (PROMs) including Tegner score, subjective hip value (SHV), modified Harris Hip Score (mHHS), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were assessed. The following morphological parameters were evaluated: LCEA, acetabular index (AI), α angle, Tönnis staging, acetabular retroversion, femoral version, femoroepiphyseal acetabular roof index (FEAR), iliocapsularis to rectus femoris ratio (IC/RF), and labral and ligamentum teres (LT) pathology.

Results

The mean follow-up was 96 months (67 to 139). The SHV, mHHS, WOMAC, and Tegner scores significantly improved (p < 0.001) at last follow-up. According to SHV and mHHS, there were three hips (7%) with poor results (SHV < 70), three (7%) with a fair score (70 to 79), eight (19%) with good results (80 to 89), and 28 (67%) who scored excellent (> 90) at the last follow-up. There were 11 subsequent operations: nine implant removals due to local irritation, one resection of postoperative heterotopic ossification, and one hip arthroscopy for intra-articular adhesions. No hips were converted to total hip arthroplasty at last follow-up. The presence of preoperative labral lesions or LT lesions did not influence any PROMs at last follow-up. From the three hips that had poor PROMs, two have developed severe osteoarthritis (> Tönnis II), presumably due to surgical overcorrection (postoperative AI < -10°).

Conclusion

PAO is reliable in treating BHD with favourable mid-term outcomes. Concomitant LT and labral lesions did not negatively influence outcomes in our cohort. Technical accuracy with avoidance of overcorrection is essential in achieving successful outcomes.

Acetabular cartilage delamination: performance of MRI using arthroscopy as the standard of reference

BACKGROUND

Femoroacetabular impingement (FAI) frequently leads to acetabular chondral delamination. Early identification and treatment of these cases is crucial to prevent further damage to the hip.

PURPOSE

To evaluate the accuracy of morphological signs of cartilage acetabular delamination in non-arthrographic magnetic resonance imaging (MRI) using intra-articular arthroscopic findings in patients undergoing FAI surgery.

MATERIAL AND METHODS

All hip MRI scans were assessed individually by three independent radiologists. Images were assessed for signs of delamination including the presence of a linear area of bright signal intensity along the acetabular subchondral bone and an area of darker tissue at the surface of the acetabular cartilage. All FAI patients underwent surgery; arthroscopy served as the standard of reference.

RESULTS

The mean age of participants was 36.1±10.9 years with 36 (48.6%) women. In the FAI group, arthroscopic surgery showed acetabular chondral delamination in 37 hips. In all hips (including the controls), MRI signs of acetabular cartilage delamination showed an average sensitivity across the three raters of 73.0% with a specificity of 71.0%. In a separate analysis of only the FAI patients, a slightly higher sensitivity (77.7%) but lower specificity (66.7%) was demonstrated. The interrater reliability showed a moderate agreement (average [k]) across the raters (0.450).

CONCLUSION

Performance of non-arthrographic MRI in diagnosing acetabular chondral delamination showed good results, yet inter-observer reproducibility among different radiologists was only moderate. Our results suggest that an increased level of awareness, for signs of delamination using MRI, will be helpful for detecting chondral delamination in patients with a history of FAI.

Radiographic Parameters of Adult Hip Dysplasia

As knowledge about the origin and morphologic characteristics of hip pain in the young adult has evolved, so too has the clinician's ability to assess for various pathologies of the hip on radiographs, magnetic resonance imaging (MRI)/magnetic resonance arthrography (MRA), and computed tomography (CT). Because there is no algorithm at this time directly indicating what to do in more subtle hip morphologies, such as microinstability and borderline hip dysplasia (BHD), a skilled hip preservation specialist must use multiple imaging sources and know how to interpret them correctly. Imaging parameters used in the workup for hip dysplasia and BHD include the lateral center-edge angle, Tönnis angle, iliofemoral line, and presence of an upsloping lateral sourcil or everted labrum, among many others. The purpose of this narrative review was to detail various established criteria and parameters on anteroposterior pelvis plain radiographs, MRI/MRA, and CT that assist in defining the nature and severity of instability present in a dysplastic hip, thereby aiding in the development of patient-specific surgical treatment plans.

Combined 3-Dimensional CT and Multidirectional CT Arthrography for Femoroacetabular Impingement and Hip Lesions: A Cross-sectional Study Comparing Imaging and Hip Arthroscopic Surgery Findings

Background

There is limited research investigating the diagnostic strength of 3-dimensional computed tomography (3D-CT) and multidirectional CT arthrography (CTA) for femoroacetabular impingement (FAI) and related hip lesions.

Purpose

To evaluate the diagnostic strength of combined 3D-CT and CTA in patients with FAI and related hip lesions by comparing it with hip arthroscopic surgery findings.

Study Design

Cohort study (diagnosis); Level of evidence, 2.

Methods

This study included patients who were suspected of having FAI and related hip lesions and who underwent a combination of 3D-CT and CTA and subsequent hip arthroscopic surgery between December 2013 and December 2017. The CT and intraoperative arthroscopic findings were recorded and compared. The sensitivity, specificity, and accuracy of 3D-CT for FAI and those of CTA for related hip lesions were calculated.

Results

A total of 114 patients with 114 hips were included in our study. There were 101 patients with positive findings and 13 patients with negative findings for FAI (including cam, pincer, and combined morphology) according to 3D-CT. The sensitivity, specificity, and accuracy of 3D-CT for FAI were 91.58%, 57.14%, and 89.47%, respectively. The sensitivity, specificity, and accuracy of CTA for labral tears were 94.64%, 100.00%, and 94.73%, respectively. For acetabular cartilage defects, the sensitivity, specificity, and accuracy of CTA were 60.71%, 91.37%, and 76.31%, respectively. For femoral cartilage defects, the sensitivity, specificity, and accuracy of CTA were 82.22%, 76.81%, and 78.94%, respectively.

Conclusion

The study results indicated that 3D-CT was able to provide excellent accuracy for FAI compared with hip arthroscopic surgery findings. In addition, multidirectional CTA demonstrated promising diagnostic strength for hip lesions such as labral tears and chondral defects.

Acetabular paralabral cysts demonstrating perineural propagation

OBJECTIVE

Acetabular paralabral cysts are common and are almost always associated with labral tears. Uncommonly, they extend into the periacetabular soft tissues or may propagate along peripheral nerves causing pain and hip dysfunction. The aim was to evaluate the clinical and MRI presentations of such cases including perineural propagation.

METHODS

Retrospective cross-sectional study with a search of electronic health records for cases of acetabular paralabral cysts demonstrating perineural propagation was performed. Clinical and MR imaging features were tabulated after re-review by experienced musculoskeletal radiologists, and available outcomes were recorded. Descriptive statistics were performed.

RESULTS

14 cases were recorded. The mean age was 56.9 years (range = 30-79 years) and female:male ratio was 1:2.6. The commonest presenting complaint was hip pain (10/14, 71.4%). Other complaints included groin pain, perineal pain and hip dysfunction. No symptoms were attributed to the acetabular paralabral cyst in 3/14 patients (21.4%). None had foot drop. The cysts were multilocular in all cases and were homogenously T2 hyperintense in 13/14 (92.9%). Labral tears were identified in 11/14 cases (78.6%). The sciatic nerve was most commonly involved in 5/14 cases (35.7%) with the obturator, medial femoral cutaneous nerve, femoral nerve, superior and inferior gluteal nerves also affected.No intervention was undertaken in 9/14 cases (64.3%). 5/14 (35.7%) underwent image guided aspiration and corticosteroid injection. 4/5 such patients reported reduced pain following the procedure.

CONCLUSION

Paralabral cysts demonstrating perineural propagation are uncommon and exhibit varied presentations. Most patients who underwent image-guided or surgical interventions reported an improvement in symptoms.

ADVANCES IN KNOWLEDGE.

This is the first description of a series of patients with acetabular paralabral cysts demonstrating perineural propagation in the literature. A comprehensive description of their clinical and imaging characteristics and interventions/outcomes where relevant is provided.

Can Non-Contrast 3T MRI scans predict the type of labral procedure in hip arthroscopy?

PURPOSE

The study proposed a simple classification system that aimed at predicting the labral procedure during hip arthroscopy using images from unenhanced 3T MRI scans.

PATENTS AND METHODS

Forty patients undergoing hip arthroscopy had their MRI scans reviewed pre-operatively by one of two senior radiologists and classified into: type 1: stable labrum with intra-substance degeneration (no labral repair required), type 2: unstable labrum, no intra-substance degeneration (labral repair required), or type 3: unstable labrum with intra-substance degeneration (Labral repair not feasible). Hip arthroscopy is carried out by one of two surgeons and classified accordingly while blinded to the radiologists' assessment.

RESULTS

The pre-operative radiological classification managed to predict the labral procedure in 29 cases out of 40 (72.5%). The gamma value was 0.83, and the kappa value was 0.46 denoting moderate agreement. The inter-class correlation coefficient was 0.52 indicating moderate reliability.

CONCLUSION

The proposed classification showed a moderate agreement between the radiological findings and arthroscopic findings. As we cannot accurately correlate the MRI findings with the type of surgical management, the surgeon should be prepared for all scenarios of labral procedures.

LEVEL OF EVIDENCE

Level IV (case series).

A Deep Learning Approach for MRI in the Diagnosis of Labral Injuries of the Hip Joint

BACKGROUND

The diagnosis of labral injury on MRI is time-consuming and potential for incorrect diagnoses.

PURPOSE

To explore the feasibility of applying deep learning to diagnose and classify labral injuries with MRI.

STUDY TYPE

Retrospective.

POPULATION

A total of 1016 patients were divided into normal (n = 168, class 0) and abnormal labrum (n = 848) groups. The abnormal group consisted of n = 111 with class 1 (degeneration), n = 437 with class 2 (partial or complete tear), and n = 300 with unclassified injury. Patients were randomly divided into training, validation, and test cohort according to the ratio of 55%:15%:30%.

FIELD STRENGTH/SEQUENCE

Fat-saturation proton density-weighted fast spin-echo sequence at 3.0 T.

ASSESSMENT

Convolutional neural network-6 (CNN-6) was used to extract, discriminate, and detect oblique coronal (OCOR) and oblique sagittal (OSAG) images. Mask R-CNN was used for segmentation. LeNet-5 was used to diagnose and classify labral injuries. The weighting method combined the models of OCOR and OSAG. The output-input connection was used to correlate the whole diagnosis/classification system. Four radiologists performed subjective diagnoses to obtain the diagnosis results.

STATISTICAL TESTS

CNN-6 and LeNet-5 were evaluated by area under the receiver operating characteristic (ROC) curve and related parameters. The mean average precision (MAP) evaluated the Mask R-CNN. McNemar's test was used to compare the radiologists and models. A P value < 0.05 was considered statistically significant.

RESULTS

The area under the curve (AUC) of CNN-6 was 0.99 for extraction, discrimination, and detection. MAP values of Mask R-CNN for OCOR and OSAG image segmentation were 0.96 and 0.99. The accuracies of LeNet-5 in the diagnosis and classification were 0.94/0.94 (OCOR) and 0.92/0.91 (OSAG), respectively. The accuracy of the weighted models in the diagnosis and classification were 0.94 and 0.97, respectively. The accuracies of radiologists in the diagnosis and classification of labrum injuries ranged from 0.85 to 0.92 and 0.78 to 0.94, respectively.

DATA CONCLUSION

Deep learning can assist radiologists in diagnosing and classifying labrum injuries.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 2.

Functional Outcomes of Arthroscopic Acetabular Labral Repair with and without Bone Marrow Aspirate Concentrate

BACKGROUND

Osteoarthritis (OA) of the hip is a debilitating condition associated with inferior outcomes in patients undergoing hip arthroscopy. To provide symptom relief and improve outcomes in these patients, bone marrow aspirate concentrate (BMAC) has been applied as an adjuvant therapy with the hope of halting progression of cartilage damage. The current study examined the clinical efficacy of BMAC application in patients undergoing arthroscopic acetabular labral repair by comparing patient-reported outcome measures (PROMs) between groups with and without BMAC application.

METHODS

Patients who received BMAC during arthroscopic acetabular labral repair from December 2016 to June 2019 were compared with a control cohort that underwent the same procedure but did not receive BMAC from November 2013 to November 2016. Patients in both cohorts were asked to prospectively complete PROMs prior to surgery and at 3, 6, 12, and 24-month follow-up intervals; those who completed the PROMs at enrollment and the 12-month follow-up were included in the study. An a priori subgroup analysis was performed among patients with moderate cartilage damage (Outerbridge grade 2 or 3). The analyses were adjusted for any differences in baseline factors between groups.

RESULTS

Sixty-two patients with BMAC application were compared with 62 control patients without BMAC application. When compared with the no-BMAC cohort, the BMAC cohort did not report significantly different mean International Hip Outcome Tool-33 (iHOT-33) scores at any postoperative time point. However, when patients with moderate cartilage damage were compared across groups, the BMAC cohort reported significantly greater mean (95% confidence interval) scores than the no-BMAC cohort at the 12-month (78.6 [72.4 to 84.8] versus 69.2 [63.3 to 75.2]; p = 0.035) and 24-month (82.5 [73.4 to 91.6] versus 69.5 [62.1 to 76.8]; p = 0.030) follow-up. Similarly, these patients reported greater score improvements at 12 months (37.3 [30.3 to 44.3] versus 25.4 [18.7 to 32.0]; p = 0.017) and 24 months (39.6 [30.4 to 48.7] versus 26.4 [19.1 to 33.8]; p = 0.029).

CONCLUSIONS

Patients with moderate cartilage injury undergoing arthroscopic acetabular labral repair with BMAC application reported significantly greater functional improvements when compared with similar patients without BMAC application.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

How to Report: Hip MRI

Writing a good magnetic resonance imaging (MRI) hip report requires a sound understanding of hip anatomy, imaging, and related pathologies. The structures of the hip most prone to pathology are the articular surfaces, labrum, subchondral bone, and gluteal tendons. Particular attention should be paid to abnormal hip morphology that is relatively common and can manifest as internal or external hip derangement. It is essential to appreciate and report the specific features of each pathology that carry clinical significance to aid patient management. This article is aimed at trainee radiologists and those less experienced with reporting hip MRI, focusing on the essential features to comment on and providing examples of terminology to use and MR images to illustrate these features.

High-Resolution Imaging for the Analysis and Reconstruction of 3D Microenvironments for Regenerative Medicine: An Application-Focused Review

The rapid evolution of regenerative medicine and its associated scientific fields, such as tissue engineering, has provided great promise for multiple applications where replacement and regeneration of damaged or lost tissue is required. In order to evaluate and optimise the tissue engineering techniques, visualisation of the material of interest is crucial. This includes monitoring of the cellular behaviour, extracellular matrix composition, scaffold structure, and other crucial elements of biomaterials. Non-invasive visualisation of artificial tissues is important at all stages of development and clinical translation. A variety of preclinical and clinical imaging methods-including confocal multiphoton microscopy, optical coherence tomography, magnetic resonance imaging (MRI), and computed tomography (CT)-have been used for the evaluation of artificial tissues. This review attempts to present the imaging methods available to assess the composition and quality of 3D microenvironments, as well as their integration with human tissues once implanted in the human body. The review provides tissue-specific application examples to demonstrate the applicability of such methods on cardiovascular, musculoskeletal, and neural tissue engineering.

Acetabular labral tears in the adolescent athlete: results of a graduated management protocol from therapy to arthroscopy

This study sought to determine outcomes of a graduated management protocol from therapy to arthroscopy for adolescents presenting with hip pain and an associated acetabular tear. Thirty-seven hips with an MRI confirmed labral tear were prospectively enrolled in a graduated management protocol created for adolescents. The protocol began with activity modification and focused physical therapy. Patients with persistent symptoms were offered an intraarticular corticosteroid injection. Those with continued symptoms were treated with arthroscopic surgery. The modified Harris hip score (mHHS) and nonarthritic hip score (NAHS) were recorded at the initial visit. Patients were contacted by telephone at 1, 2, and 5 years from enrollment for repeat assessment with mHHS and NAHS. At presentation, the mean mHHS and NAHS for the entire cohort was 66.4  ±  11.4 and 70.2  ±  12.6, and these values improved significantly to 89.3  ±  10.6 and 87.0  ±  11.4 at a mean follow-up of 35.7  ±  18.3 months (range 11.7-64.4 months). Forty-two percent of hips were managed with physical therapy and activity modifications alone, 28% of hips progressed to a steroid injection but did not require surgery, and 31% required arthroscopic intervention. Seventy-three percent of hips treated with activity modification alone, 80% treated with an injection, and 82% of hips treated with arthroscopic repair met the minimal clinically significant difference (MCID) (P = 0.859). At an average of 36 months follow-up, the majority (78%) of adolescent patients with an acetabular labral tear will achieve the MCID utilizing a graduated management protocol.

India ink artifact on Dixon out-of-phase images can be used as a landmark to measure joint space width at MRI

PURPOSE

The purpose of this study was to test the feasibility of joint space width (JSW) measurement on Dixon MR images with the "India ink" artifact between cartilage and bone marrow as a landmark for the subchondral plate and to correlate it with radiographic JSW.

MATERIALS AND METHODS

Both hands of six volunteers (three women, three men; mean age, 36.7 ± 10.4 [SD] years) and 24 patients with early rheumatoid arthritis (16 women, 8 men; mean age, 45.7 ± 14.5 [SD] years) were imaged with MRI Dixon sequences and radiographs. Two radiologists (R1, R2) separately measured JSW in 11 joints per hand on all Dixon images in volunteers, on contrast-enhanced T1-weighted out-of-phase images in patients and on radiographs in both groups. Inter-technique, intra-observer and inter-observer agreements were assessed using intraclass correlation coefficient (ICC) and Bland Altman analysis.

RESULTS

In volunteers, agreement between JSW measurements on MRI and radiographs was the highest with T1-weighted Dixon out-of-phase images (mean ICC ranging from 0.69 to 0.76 for R1 and 0.65 to 0.74 for R2). In patients, median bias between JSW measurements at first and second readings was not statistically significantly different from 0 on T1-weighted Dixon out-of-phase images (mean bias of 0.00 and + 0.01 mm) and radiographs (mean bias of 0.00 and +0.01 mm). Median bias of the difference between measurements of R1 and R2 was statistically significantly different from 0 on T1-weighted Dixon out-of-phase images (mean bias of -0.11 and -0.09 mm; P < 0.039) and radiographs (mean bias of -0.24 and -0.20 mm; P < 0.035).

CONCLUSION

Measurement of hand JSW on T1-weighted Dixon out-of-phase images using India ink artifact as a landmark for the subchondral plate is repeatable and reproducible.

[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.

Magnetic Resonance Imaging Predictors of Chondral Lesions in Patients With Femoroacetabular Impingement: An Analysis of 545 Cases

PURPOSE

A large prospective cohort was used (1) to evaluate the overall ability of magnetic resonance imaging (MRI) to detect Outerbridge grade III and IV cartilage defects found during surgery and (2) to identify the specific MRI findings most associated with these cartilage defects so that the practicing hip arthroscopist can better predict cartilage injury before surgery.

METHODS

All patients undergoing hip arthroscopy between February 2015 and May 2017 at 1 institution were enrolled in a prospective cohort. Intra-articular findings were documented at the time of surgery. MRI reports were retrospectively reviewed for radiologist-reported articular cartilage, osseous, or synovial abnormalities. Sensitivity and specificity of MRI findings were calculated; multivariate logistic regression analysis determined which findings were associated with high-grade chondral damage at the time of arthroscopy and used to create an online risk calculator, https://orthop.washington.edu/hiprisk/.

RESULTS

Of 598 patients who underwent hip arthroscopy, 550 had MRI reports available for review (92%). Grade III and IV cartilage injuries were reported on arthroscopy in 70 patients (13%) of average age 33 ± 13 years. On univariate analyses, individual MRI findings were not sensitive in detection of articular cartilage injury (mean 22%; range, 1.4%-46%), but positive findings were highly specific (mean 90%,; range, 76%-99%). Multivariate analysis revealed that older age (odds ratio [OR] 1.09 [1.06-1.11], P < .001) and osseous findings such as subchondral cyst or edema (OR 4.77 [2.51-9.05], P < .001) were most predictive of grade III and IV defects (P < .001).

CONCLUSION

MRI was a specific but not sensitive tool in diagnosing articular cartilage injury. Surgeons should be aware that osseous findings such as cysts or edema are highly predictive of full-thickness cartilage loss in FAI.

LEVEL OF EVIDENCE

Level III, development of diagnostic criteria (consecutive patients with consistently applied reference standard, no blinding).

Prevalence of early hip OA features on MRI in high-impact athletes. The femoroacetabular impingement and hip osteoarthritis cohort (FORCe) study

OBJECTIVE

To compare early hip osteoarthritis (OA) features on magnetic resonance imaging (MRI) in high-impact athletes with and without hip and/or groin pain, and to evaluate associations between early hip OA features, the International Hip Outcome Tool (iHOT33) and Copenhagen Hip and Groin Outcome Score (HAGOS).

DESIGN

This case-control study evaluated data of the femoroacetabular impingement and hip osteoarthritis cohort (FORCe). One hundred and eighty-two symptomatic (hip and/or groin pain >6 months and positive flexion-adduction-internal-rotation (FADIR) test) and 55 pain-free high-impact athletes (soccer or Australian football (AF)) without definite radiographic hip OA underwent hip MRI. The Scoring Hip Osteoarthritis with MRI (SHOMRI) method quantified and graded the severity of OA features. Each participant completed the iHOT33 and HAGOS.

RESULTS

Hip and/or groin pain was associated with higher total SHOMRI (0-96) (mean difference 1.4, 95% CI: 0.7-2.2), labral score (adjusted incidence rate ratio (aIRR) 1.33, 95% CI: 1.1-1.6). Differences in prevalence of cartilage defects, labral tears and paralabral cysts between symptomatic and pain-free participants were inconclusive. There was a lower prevalence of effusion-synovitis in symptomatic participants when compared to pain-free participants (adjusted odds ratio (aOR) 0.46 (95% CI: 0.3-0.8). Early hip OA features were not associated with iHOT33 or HAGOS.

CONCLUSIONS

A complex and poorly understood relationship exists between hip and/or groin pain and early hip OA features present on MRI in high-impact athletes without radiographic OA. Hip and/or groin pain was associated with higher SHOMRI and labral scores.

Comparison of 2D, 3D, and radially reformatted MR images in the detection of labral tears and acetabular cartilage injury in young patients

OBJECTIVE

The purpose of this study was to compare the utility of two-dimensional high-resolution (2D), 3-dimensional with multiplanar reconstruction (3D MPR), and radially reformatted (RR) MRIs when evaluating the complexities of the hip joint in patients with femoroacetabular impingement (FAI). We hypothesized RR would be superior in detecting labral pathology and 2D would be superior in detecting transition zone and acetabular cartilage injury.

MATERIALS AND METHODS

2D, 3D MPR, and RR MRIs of 33 patients, who later underwent surgical treatment for FAI, were evaluated for sensitivity, specificity, and accuracy. Bland-Altman methods were used to estimate agreement between each method and the gold-standard, arthroscopic visualization of the hip joint, regarding the percentage of the hip joint affected by each injury type.

RESULTS

3D MPR and RR groupings were associated with the highest sensitivity and accuracy for labral injury. 3D MPR demonstrated the smallest bias in assessing the percentage of joint affected by labral injury and was the most accurate in identifying acetabular cartilage injury, whereas RR had the smallest mean difference in assessing the percentage of joint affected by acetabular cartilage injury. 2D was the most accurate in identifying transition zone injuries, while RR was superior in assessing the percentage of the joint affected by transition zone injury.

CONCLUSIONS

Our results suggest that including both 3D MPR and RR MRI groupings is favorable for accurate joint visualization and well-informed treatment planning, especially given that labral injury is a main source of pain and dysfunction for FAI patients.

Arthroscopic assessment of concomitant intraarticular pathologies in patients with osteonecrosis of the femoral head

This study's purpose is to arthroscopically assess the occurrence of intraarticular pathologies in patients with osteonecrosis of the femoral head (OFNH) and to compare arthroscopic with radiologic findings. In a retrospective cohort analysis of ONFH patients undergoing combined core decompression (CD) and hip arthroscopy, concomitant intraarticular pathologies were qualitatively and quantitatively assessed by means of arthroscopy. Intraoperative findings were compared with preoperative radiodiagnostics. Descriptive statistics were performed with results displaying type, degree and prevalence of co-pathologies. Based on a cohort of 27 hips with ONFH at ARCO stages II and III, 26 (96.3%) presented with concomitant intraarticular findings. Cam-deformity (n = 22; 81.5%), labral defects (n = 23; 85.2%) and chondral defects (n = 20; 74.1%) were the most frequent. Four hips (14.8%) had foveal ligament anomalies. Intraoperative detection of cam-deformity positively correlated with radiologically assessed pathologic α angles (p = 0.09). Radiologic evaluation of the acetabular labrum distinctly differed from arthroscopic findings. Reliable statements concerning the cartilage status were not possible due to the great difference in quality of the magnetic resonance imaging (MRIs). The results of this study revealed an arthroscopically proven prevalence of co-pathologies in >95% of patients with ONFH. Cam-type deformity, labral anomalies and chondral defects were the most frequent. Comparison of arthroscopic and radiologic findings showed coherent results regarding cam-deformity but revealed distinct difficulties in the assessment of the labral and chondral status emphasizing the need for standardization of preoperative radiodiagnostics. Moreover, it still has to be evaluated whether combined CD and arthroscopy can improve on the overall outcomes achieved by performance of CD only.

Microinstability of the hip: a systematic review of the imaging findings

OBJECTIVES

To undertake a systematic review of the morphologic features associated with hip microinstability and determine whether there are suggestive or diagnostic imaging findings.

METHODS

Four electronic databases were searched up to September 2019 to identify original research reporting morphologic features in individuals with either a clinical diagnosis of hip microinstability (instability without overt subluxation/dislocation) or those with symptomatic laxity demonstrated on imaging (increased femoral head translation/distraction or capsular volume). Studies focussing on individuals with pre-existing hip conditions (including definite dysplasia (lateral centre edge angle < 20°), significant trauma, previous dislocation or surgery were excluded. Methodological quality was assessed by the Quality Assessment of Diagnostic Accuracy Studies 2 tool.

RESULTS

Twenty-two studies met inclusion criteria (clinical diagnosis of microinstability n = 15 and demonstration of laxity n = 7). Imaging information gathered from the studies includes radiographs (n = 14), MRI (n = 6), MR arthrography (n = 4), CT (n = 1) and intraoperative examination. Most studies exhibited design features associated with an overall high or unclear risk of bias. Some dysplastic features are associated with microinstability or laxity reference measures; however, microinstability is frequently diagnosed in those with a lateral centre edge angle > 25°. Other associated imaging findings reported include impingement morphology, anterior labral tearing, femoral head chondral injury, ligamentum teres tears and capsular attenuation.

CONCLUSIONS

The current literature does not provide strong evidence for imaging features diagnostic of microinstability. In the appropriate clinical context, dysplastic morphology, anterior labral tears and ligamentum teres tears may be suggestive of this condition although further research is needed to confirm this.

PROSPERO REGISTRATION

CRD42019122406.

Magnetic resonance imaging of the hip: anatomy and pathology

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

Hip Joint Pathology Among Men Referred to Urology for Chronic Orchialgia: A Source for Misdiagnosis and Opportunity for Quality Improvement

OBJECTIVE

To evaluate the findings of magnetic resonance imaging (MRI) of the ipsilateral hip(s) as part of the workup of men with chronic orchialgia (CO).

METHODS

Following IRB approval, a retrospective chart review was performed from a single surgeon database of all men with a diagnosis of CO from June 2018 to October 2019 who underwent subsequent hip MRI evaluation.

RESULTS

Ten men were identified. Median age was 51 years and median duration of pain was 10 months. MRI was obtained after testis pathology was ruled out. Pain was noted in the groin (100%) and hip (50%). Hip MRI identified overt labral tears in 8 men (10/12 hips evaluated, 83%) and labral fraying in the remaining 2 (16.7%). Standard plain film radiography was performed in 6 men prior to MRI, all of which were negative. Following MRI, 5 men underwent hip injection with steroid and local analgesic with lasting resolution (2 men) or significant improvement in pain (2 men; 80%, follow-up 3-15 months). Two men had complete resolution of pain with 8 weeks of physical therapy.

CONCLUSION

Hip MRI has a high rate of diagnosis of labral tear in appropriately selected men referred to the urologist for CO. Identification of orthopedic pathology may avoid unnecessary antibiotics, opiates, or urological surgery. Referrals to orthopedics and/or physical therapy for intervention may lead to resolution of pain.

Does gadolinium improve magnetic resonance arthrography of the hip beyond fluid distension alone?

AIM

To determine if there is a difference in the detection of labral tears and cartilage lesions using the T2-weighted sequences of magnetic resonance arthrography (MRA) only, which simulate MRA with saline alone, compared with the full examination including T1-weighted sequences.

MATERIALS AND METHODS

One hundred hip MRA examinations performed at 3 T were identified retrospectively. Each study was reviewed by a musculoskeletal radiologist using either the T2-weighted sequences only (without gadolinium-based contrast agent [GBCA] effect) or the entire examination, including T1-weighted sequences (with GBCA effect). Receiver operating characteristic (ROC) curves were calculated for both groups and compared within a non-inferiority framework, using - 0.10 as the limit of non-inferiority.

RESULTS

For labral tears, the difference area under the curve (AUC) was -0.004 (95% confidence interval [CI]: -0.064-0.056, p=0.90). For acetabular cartilage lesions, the difference AUC was 0.011 (95% CI: -0.073-0.096, p=0.79). For femoral cartilage lesions, the difference AUC was -0.059 (95% CI: -0.206-0.087, p=0.43).

CONCLUSION

T2-weighted sequences alone were not inferior in diagnostic accuracy compared with the full examination (including T1-weighted sequences with intra-articular GBCA) in detecting acetabular cartilage lesions and labral tears. Further study with prospective comparison of saline injectate to GBCA-containing injectate may help clarify the necessity of continued GBCA use in MRA of the hip.

Diagnosing acetabular labral tears with hip traction sonography: a case series

PURPOSE

Three cases of acetabular labral tear (ALT) diagnosed with sonography (US) are reported. We aim to show utility for US with the addition of manual hip traction as an adjunctive modality to the current diagnostic imaging of choice, magnetic resonance arthrography (MRA), for diagnosing ALT.

METHODS

Three cases of young athletic patients with similar clinical presentations are reported. All received US examination of the hip with attention to the labrum that included a novel long-axis hip traction technique which assisted in diagnosing ALT.

RESULTS

In the first and second cases, MRA and orthopedic consult were obtained for confirmation of the diagnosis. Arthroscopy was performed to correct the ALT. The third patient declined an MRA. Conservative management consisted of McKenzie method active care, resulting in return to sport in the third case.

CONCLUSION

These three cases demonstrate the clinical and sonographic presentation of ALT. The dynamic long-axis hip traction protocol facilitated the use of US as an adjunctive modality for diagnosing ALT by increasing the visualization of the defect.

Value of response to anesthetic injection during hip MR arthrography to differentiate between intra- and extra-articular pathology

PURPOSE

To determine the value of anesthetic injection during hip MR arthrography (anesthetic MRA) to differentiate between intra- and extra-articular pathology in patients with hip pain.

MATERIALS AND METHODS

This retrospective study was IRB-approved and HIPAA-compliant. We included 75 consecutive adult patients (46 women, mean age 38 ± 13 years) who were referred for MRA. All patients underwent a focused hip examination including active flexion, passive flexion, and passive flexion with internal and external rotation, immediately prior to injection. Anesthetic MRA was performed following fluoroscopically guided intra-articular injection of contrast mixed with anesthetic. Following the injection, the hip examination was repeated, and the pain response was recorded. Clinical records, including response to corticosteroid injections, physical therapy notes, and operative reports were reviewed for verification of intra- and extra-articular pathology as the source of hip pain (gold standard). The positive (PPV) and negative predictive values (NPP) of anesthetic MRA to differentiate between intra- and extra-articular pathology were calculated.

RESULTS

On MRI, 41 patients had only intra-articular and 5 patients only extra-articular pathology, while 29 patients had both, intra- and extra-articular pathology. Forty-three patients had pain relief and 32 patients had no pain relief after anesthetic injection. PPV of anesthetic MRA to detect intra-articular pathology was 91% and NPV was 67%.

CONCLUSION

Anesthetic MRA can be used as an adjunct to define the origin of hip pain. A positive response suggests intra-articular pathology which can be helpful to localize the source of pain in equivocal cases where both intra- and extra-articular pathology are evident on MRI.

Validity of direct magnetic resonance arthrogram in patients with femoroacetabular impingement and their outcome post hip arthroscopy

Femoroacetabular Impingement is an established cause of labral tears and chondral delamination. The aim was to test the validity of direct magnetic resonance arthrogram [dMRA] in the diagnosis of the same. We also looked at the short term functional outcome in these patients post hip arthroscopy. The dMRA is valuable in diagnosing labral tears nevertheless poor in detecting cartilage delamination. Hip arthroscopic intervention provided a good short-term functional outcome; however, should be offered with caution in patients over 40 years. To our knowledge, this is the single largest series published with similar methodology.

Single-Stage Arthroscopic Autologous Matrix-Enhanced Chondral Transplantation (AMECT) in the Hip

Chondral defects of the acetabulum in patients with femoroacetabular impingement syndrome are an increasingly recognized cause of worse outcomes after treatment. Multiple procedures have been described for the treatment of hip cartilage lesions including microfracture, autologous chondrocyte implantation, matrix-induced autologous chondrocyte implantation, and autograft and allograft transplantation. However, many of these techniques have poor long-term outcomes, require multiple surgical procedures, or rely on planned preoperative identification of the chondral lesion. This Technical Note describes our technique of autologous matrix-enhanced chondral transplantation, a single-stage treatment for acetabular cartilage lesions that harvests chondral tissue from the femoral cam deformity and combines it with chondral extracellular matrix, growth factors, and autologous peripheral blood.

Magnetic Resonance Arthrography, a valuable pre-operative imaging modality in femoro-acetabular impingement

Background

The diagnostic accuracy of MR arthrography in preoperative assessment of labral tears and chondral abnormalities in femoroacetabular impingement patients.

A non-randomized control study including 31 FAI patients (17 male and 14 females, mean age 31.9 years). All patients underwent MR arthrography after US-guided intra-articular contrast injection. Conventional and MR arthrography images were evaluated for bone abnormalities (including alpha angle and acetabular depth measurements), labral tears, and chondral abnormalities. The results were correlated to arthroscopy as the gold standard. Sensitivity, specificity, PPV, and NPV in the detection of labral tears and chondral abnormalities were statistically calculated.

Results

The included FAI patients presented cam (mean age 30.4 years ± 6.8 years), pincer (mean age 33.6 years ± 9.8 years), and mixed (mean age 36.6 years ± 12.9 years) types with the predominance of cam type. Cam type predominated in the male, while pincer and mixed types predominated in female patients. MR arthrography detected 41 labral tears in 23 patients with 87.5%, 71.4%, 91.3%, and 62.5% sensitivity, specificity, PPV, and NPV, respectively, and detected chondral abnormalities in 13 patients with 66.7%, 92.3%, 92.3%, and 66.7% sensitivity, specificity, PPV, and NPV, respectively.

Conclusion

MR arthrography is a valuable imaging modality in preoperative assessment of FAI patients. Besides identifying the type of impingement through alpha angle and acetabular depth measurements, it detects labral tears with high sensitivity and PPV. Although less sensitive in detection of chondral abnormalities, our results showed high specificity.

The Extension-Thickness-Damage (ETD) score: a pre-operative hip MR arthrography-based classification to predict type of labrum surgery

INTRODUCTION

Hip magnetic resonance arthrography (MRA) is the pre-operative imaging modality of choice in patients with labral damage, with several classifications of labral tears having been reported based on MRA findings. Nevertheless, none of the available classification systems allows the surgeon to predict before surgery how a labral tear could be treated. Our purpose was to develop a new MRA-based scoring system of labral tears to predict before surgery the treatment option more suitable for labral tears.

MATERIALS AND METHODS

Forty-seven patients (29 males and 18 females; mean age: 35.9 ± 12.4) performed hip MRA for suspicious of femoroacetabular impingement and were afterwards subjected to arthroscopic treatment. Two musculoskeletal radiologists reviewed all pre-operative examinations and provided the Extension-Thickness-Damage score for each patient, based on Extension of tear, Thickness of labrum, and type of Damage. Chondral lesions grading was based on the arthroscopic findings according to Konan classification. For statistical purposes, patients were divided into two groups, depending on the type of treatment: labral repair or debridement. Mann-Whitney U, Chi-square, receiver operator curves, and Cohen kappa statistics were used.

RESULTS

35/47 underwent repair, while 12/47 were debrided. In both groups, the median chondral damage was grade III, with no significant differences (p = 0.439). The median Extension-Thickness-Damage score in the repair group (6) was significantly lower (p < 0.001) than that in the debridement group (8). The highest diagnostic performance (area under the curve) of Extension-Thickness-Damage was 0.819. The inter-observer agreement was substantial in the evaluation of Extension (k = 0.626) and Thickness (k = 0.771), and almost perfect for Damage (k = 0.827). Higher scores of Extension and Thickness were more frequently associated with debridement (p < 0.001; p = 0.0016, respectively), with no significant differences on the basis of Damage parameter (p = 0.284).

CONCLUSIONS

The MRA-based Extension-Thickness-Damage score could represent a helpful pre-operative tool, expressing the extent of the damage and its reparability before arthroscopy.

Chondral lesions in the hip: a review of relevant anatomy, imaging and treatment modalities

The diagnosis and treatment of chondral lesions in the hip is an ongoing challenge in orthopedics. Chondral lesions are common and several classification systems exist to classify them based on severity, location, radiographic parameters, and potential treatment options. When working up a patient with a potential hip chondral lesion, a complete history, thorough physical exam, and ancillary imaging are necessary. The physical exam is performed with the patient in standing, supine, prone, and lateral positions. Plain film radiographs are indicated as the first line of imaging; however, magnetic resonance arthrogram is currently the gold standard modality for the diagnosis of chondral lesions outside of diagnostic arthroscopy. Multiple treatment modalities to address chondral lesions in the hip exist and new treatment modalities continue to be developed. Currently, chondroplasty, microfracture, cartilage transplants (osteochondral autograft transfer, mosaicplasty, Osteochondral allograft transplantation) and incorporation of orthobiologics (Autologous chondrocyte implantation, Autologous matrix-induced chondrogenesis, Mononuclear concentrate in platelet-rich plasma) are some techniques that have been successfully applied to address chondral pathology in the hip. Further refinement of these modalities and research in novel techniques continues to advance a surgeon’s ability to address chondral lesions in the hip joint.

Simultaneous multi-slice MR imaging of the hip at 3 T to reduce acquisition times and maintain image quality

Background

Newly developed simultaneous multi-slice (SMS) scans are now being introduced as a clinical application in neuroimaging. We examined the feasibility of SMS scans for joint imaging. The purpose of the present study was to prospectively compare the resolution and specific absorption rate (SAR) obtained using SMS to those of conventional methods in hip joint magnetic resonance imaging (MRI) and establish whether imaging times may be reduced using SMS in 3 T MRI and if image quality is affected.

Methods

Twenty-one patients (4 men and 17 women, average age, 51.5 years, range: 22 to 76 years) with hip pain underwent MR examinations of the unilateral hip joint. Three board-certified radiologists independently and blindly evaluated the images obtained with and without SMS using window and level settings and magnification according to personal preferences. Individual SAR values were measured for each protocol. A Wilcoxon signed-rank test and a t-statistic test were used for statistical analyses. Signal-to-noise ratio (SNR) was also compared using a phantom.

Results

SMS imaging maintained equivalent image quality to conventional imaging for evaluating the morphology of the hip joint, and also reduced imaging times by approximately 40%. SMS images had significantly higher SAR values than conventional images. The rate of difference (SMS/conventional) in SNR ranged between 80 and 111%.

Conclusions

Based on its significantly lower acquisition times and the maintenance of similar image quality to conventional imaging, SMS may be applied to morphological evaluations of hip joint disorders without significantly increasing SAR.

Validation of scoring hip osteoarthritis with MRI (SHOMRI) scores using hip arthroscopy as a standard of reference

PURPOSE

To validate SHOMRI gradings in preoperative hip magnetic resonance imaging (MRI) with intra-arthroscopic evaluation of intraarticular hip abnormalities.

METHODS

Preoperative non-arthrographic 3.0-T MRIs of 40 hips in 39 patients (1 patient with bilateral hip surgery) with femoroacetabular impingement (FAI) syndrome (mean age, 34.7 years ± 9.0; n = 16 females), refractory to conservative measures, that underwent hip arthroscopy were retrospectively assessed by two radiologists for chondrolabral abnormalities and compared with intra-arthroscopic findings as the standard of reference. Arthroscopically accessible regions were compared with the corresponding SHOMRI subregions and assessed for the presence and grade of cartilaginous pathologies in the acetabulum and femoral head. The acetabular labrum was assessed for the presence or absence of labral tears. For the statistical analysis sensitivity and specificity as well as intraclass correlation (ICC) for interobserver agreement were calculated.

RESULTS

Regarding chondral abnormalities, 58.8% of the surgical cases showed chondral defects. SHOMRI scoring showed a sensitivity of 95.7% and specificity of 84.8% in detecting cartilage lesions. Moreover, all cases with full-thickness defects (n = 9) were identified correctly, and in n = 6 cases (out of n = 36 with partial-thickness defects) the defective cartilage was identified but the actual depth overestimated. Labral tears were present in all cases and the MR readers identified 92.5% correctly. ICC showed a good interobserver agreement with 86.3% (95% CI 80.0, 90.6%) CONCLUSION: Using arthroscopic correlation, SHOMRI grading of the hip proves to be a reliable and precise method to assess chondrolabral hip joint abnormalities.

KEY POINTS

• Assessment of hip abnormalities using MRI with surgical correlation. • Comparing surgery and MRI by creating a hybrid anatomic map that covers both modalities. • Non-arthrographic use of 3.0-T MRI provides detailed information on cartilage and labral abnormalities in hip joints.

A posterior labral cyst associated with an anterior labral tear of the hip

Paralabral cysts are often associated with labral and other intraarticular hip pathology; MRI as well as diagnostic ultrasound can assist in diagnosis. Although often considered a coincidental finding, paralabral cysts can be a separate pain generator about the hip through compression of surrounding anatomy. They can also be initially mistaken for malignancy or other pathology by providers unfamiliar with their appearance. We present the case of an active 33-year-old female with right hip pain secondary to a large symptomatic posterior acetabular paralabral cyst with concomitant anterior labral tear. Following diagnosis on MRI, treatment included ultrasound-guided aspiration of the cyst, followed by arthroscopic anterior labral repair and separate cyst decompression from a posterior portal. The patient had complete resolution of her symptoms.

What is the prevalence of imaging-defined intra-articular hip pathologies in people with and without pain? A systematic review and meta-analysis

BACKGROUND

Intra-articular hip pathologies are thought to be associated with the development of hip and groin pain. A better understanding of the relationship between symptoms and imaging findings may improve the management of individuals with intra-articular hip pathologies.

OBJECTIVE

To undertake a systematic review and meta-analysis to determine the prevalence of intra-articular hip pathologies in individuals with and without pain.

METHODS

Seven electronic databases were searched in February 2017 for studies investigating the prevalence of intra-articular hip pathologies using MRI, MRA or CT. Two independent reviewers conducted the search, study selection, quality appraisal and data extraction. Meta-analysis was performed when studies were deemed homogenous, with a strength of evidence assigned to pooled results.

RESULTS

In general, studies were moderate to high risk of bias, with only five studies adjudged to be low risk of bias. The 29 studies reporting on the prevalence of intra-articular hip pathologies identified limited evidence of a labral tear prevalence of 62% (95% CI 47% to 75%) in symptomatic individuals, with moderate evidence identifying a labral tear prevalence of 54% (95% CI 41% to 66%) in asymptomatic individuals. Limited evidence demonstrated a cartilage defect prevalence of 64% (95% CI 25% to 91%) in symptomatic individuals, compared with moderate evidence of a cartilage defect prevalence of 12% (95% CI 7% to 21%) in asymptomatic individuals.

CONCLUSION

The prevalence of intra-articular hip pathologies is highly variable in both symptomatic and asymptomatic populations. The prevalence of intra-articular hip pathologies appears to be higher in symptomatic individuals. However, imaging-defined intra-articular hip pathologies are also frequently seen in asymptomatic individuals, highlighting a potential discordant relationship between imaging pathology and pain.

PROSPERO REGISTRATION NUMBER

CRD42016035444.

Preventing Overdiagnosis of Acetabular Labral "Tears" in 40-Plus-year-old Patients: Shouldn't these be called Labral "Fissures" Instead?

Acetabular labral tears represent a common finding on magnetic resonance imaging of the hip. Labral tears can arise from a multitude of underlying pathological processes or they may be an asymptomatic incidental finding. The prevalence of labral tears and their lack of specificity make this an area vulnerable to potential overdiagnosis. The overdiagnosis of labral tears leads to overtreatment by exposing patients to unnecessary surgeries as well as complications ranging from unsatisfying outcomes to deep venous thrombosis. This risk is compounded by the tabloid popularization of labral surgeries by celebrities such as Lady Gaga, which could potentiate patient perception of a two-tiered level of health care. Following a similar situation with spine nomenclature, one solution to this issue is to reclassify "labral tears" as "labral fissures" in some or all cases to mitigate the acute traumatic connotation of the term "tear."

Comprehensive Clinical Evaluation of Femoroacetabular Impingement: Part 3, Magnetic Resonance Imaging

Radiologic imaging is an essential supplement to the physical examination in the evaluation of a patient with femoroacetabular impingement. Plain radiographs are the initial modality of choice for the evaluation of bony anatomy and pathology. Magnetic resonance imaging supplements the physical examination and standard radiographs by enabling qualitative and quantitative evaluation of both articular cartilage and soft tissues about the hip. Magnetic resonance imaging also provides improved 3-dimensional characterization of the bony anatomy owing to the multiplanar nature of this technique. This article describes a comprehensive approach to interpretation of magnetic resonance examination of the hip.

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.