Imaging of Disease and Normal Variant Patterns in Pediatric Hips.

The pediatric hip undergoes significant changes from infancy through adolescence. Proper maturation is crucial for the development of a stable and functional hip joint. Imaging interpretation of the pediatric hip requires distinguishing normal variants and maturation patterns from pathology. We review femoral ossification centers, variants, and conditions that affect the proximal femur, such as Legg-Calvé-Perthes disease; the acetabulum, such as developmental hip dysplasia; the acetabular labrum, such as femoroacetabular impingement; and synovial pathology in children through adolescence. Understanding the spectrum of hip conditions and using advanced imaging techniques are essential for the accurate diagnosis and effective management of pediatric hip disorders.

Anatomical Proximity Between Sciatic Nerve and Ischial Spine and its Relationship to the Development of Deep Gluteal Pain Syndrome.

OBJECTIVE: Deep gluteal syndrome (DGS) is a medical diagnosis in which the pathoanatomy of the subgluteal space contributes to pain. The growing recognition that gluteal neuropathies can be associated with the presence of a bone-neural conflict with irritation or compression may allow us to shed some light on this pathology. This study aims to determine whether the location of the sciatic nerve (SN) in relation to the ischial spine (IS) contributes to the development of DGS. METHODS: The SN - IS relationship was analyzed based on magnetic resonance imaging (MRI) in 15 surgical patients (SPs), who underwent piriformis release, and in 30 control patients who underwent MRI of the pelvis for reasons unrelated to sciatica. The SN exit from the greater sciatic foramen was classified as either zone A (medial to the IS); zone B (on the IS); or zone C (lateral to the IS). RESULTS: The SN was significantly closer to the IS in SPs than in MRI controls (P = 0.014). When analyzing patients of similar age, SNs in SPs were significantly closer (P = 0.0061) to the IS, and located in zone B significantly more (P = 0.0216) as compared to MRI controls. Patients who underwent surgery for piriformis release showed a significant decrease in pain postoperatively (P < 0.0001). CONCLUSIONS: The results from this study suggest that the relationship between the IS and SN may play a role in the development of DGS. This may also help establish which patients would benefit more from surgical intervention.

Chronic Nonspinal Osteomyelitis in Adults: Consensus Recommendations on Percutaneous Bone Biopsies from the Society of Academic Bone Radiologists.

The diagnosis and management of chronic nonspinal osteomyelitis can be challenging, and guidelines regarding the appropriateness of performing percutaneous image-guided biopsies to acquire bone samples for microbiological analysis remain limited. An expert panel convened by the Society of Academic Bone Radiologists developed and endorsed consensus statements on the various indications for percutaneous image-guided biopsies to standardize care and eliminate inconsistencies across institutions. The issued statements pertain to several commonly encountered clinical presentations of chronic osteomyelitis and were supported by a literature review. For most patients, MRI can help guide management and effectively rule out osteomyelitis when performed soon after presentation. Additionally, in the appropriate clinical setting, open wounds such as sinus tracts and ulcers, as well as joint fluid aspirates, can be used for microbiological culture to determine the causative microorganism. If MRI findings are positive, surgery is not needed, and alternative sites for microbiological culture are not available, then percutaneous image-guided biopsies can be performed. The expert panel recommends that antibiotics be avoided or discontinued for an optimal period of 2 weeks prior to a biopsy whenever possible. Patients with extensive necrotic decubitus ulcers or other surgical emergencies should not undergo percutaneous image-guided biopsies but rather should be admitted for surgical debridement and intraoperative cultures. Multidisciplinary discussion and approach are crucial to ensure optimal diagnosis and care of patients diagnosed with chronic osteomyelitis.

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.

Ultrasound-guided nerve block prior to biopsy of suspected neurogenic tumors: safety and feasibility in a pilot study.

OBJECTIVE: The aim of this study is to investigate the safety and feasibility of ultrasound-guided nerve block prior to biopsy of potentially neurogenic tumors. MATERIALS AND METHODS: A retrospective review of the medical record from June 2017 to June 2022 identified ultrasound-guided biopsies of potentially neurogenic tumors that were performed with a pre-procedural nerve block. Patient demographics, biopsy site, number of passes, needle gauge, use of sedation, pathology results, and procedural complications were recorded and summarized. RESULTS: The structured search found 16 patients that underwent biopsies of 18 potentially neurogenic tumors with the use of a pre-procedural nerve block at a variety of upper and lower extremity locations. Average patient age was 52 (range 18-78) and 9 patients (56%) were female. Of the 16 patients, 10 were performed without intravenous sedation. Three patients were unable to tolerate biopsy until a nerve block was used. All biopsies yielded a diagnostic sample with 13 of the tumors neurogenic in origin. One patient reported mild postprocedural pain which resolved with conservative treatment; no other complications were reported. CONCLUSION: Nerve block prior to ultrasound-guided biopsy of potentially neurogenic tumors is a safe and feasible technique. Further study is needed to determine the extent to which nerve block can decrease intra-procedural pain and reduce or eliminate the need for sedation during biopsy.

The posterior crescent sign on MRI and MR arthrography: is it a marker of hip dysplasia and instability?

OBJECTIVE: To evaluate the prevalence of the 'posterior crescent sign' in symptomatic patients referred for MRI/MR arthrogram of the hip and identify any correlation with imaging features of joint pathology. MATERIALS AND METHODS: Retrospective imaging assessment of a cohort of 1462 hips, from 1380 included MR examinations (82 bilateral) retrieved from a search of all examinations in patients 16-50 years old from June 2018 to June 2021, with median age 45.8 years (range 17.8-50.0) and 936 hips (64%) in women. Radiographic and MR findings related to hip dysplasia, femoroacetabular impingement and osteoarthritis were assessed. RESULTS: Fifty-one hips (3.5%) were positive for the posterior crescent sign, median age of 45.8 years (range 17.8-50.0) and 29 (58%) in women. Radiographic findings included the following: mean lateral centre edge angle (LCEA) 22.2° (± 7.8°) with LCEA < 20° in 15 (31%) and LCEA 20-25° in 17 (35%) and mean acetabular index (AI) of 13.1° (± 5.8°) with AI > 13° in 22 (45%). MR findings included the following: mean anterior acetabular sector angle (AASA) 54.3° (± 9.8°), mean posterior acetabular sector angle (PASA) 92.7° (± 7.0°), labral tear at 3-4 o'clock in 20 (39%), high-grade acetabular chondral loss in 42 (83%) and ligamentum teres abnormality in 20 (39%). CONCLUSION: The posterior crescent sign occurs in 3.5% of symptomatic young and middle-aged adults on MR. It is associated with overt and borderline hip dysplasia and other findings of hip instability. It is also associated with osteoarthritis in some cases and should be interpreted with caution in these patients.

Contrast-enhanced ultrasound-guided musculoskeletal biopsies: our experience and technique.

OBJECTIVE: To present our experience with contrast-enhanced ultrasound (CEUS)-guided musculoskeletal soft tissue biopsies in a busy interventional clinic. MATERIALS AND METHODS: After IRB approval was obtained and informed consent was waived, we retrospectively reviewed all CEUS-guided musculoskeletal biopsies performed from December 1, 2018 to March 2, 2020. Relevant pre-procedure imaging was reviewed. Number of samples, suspected necrosis on pre-procedure imaging, specimen adequacy for pathologic analysis, correlation with pathologic diagnosis of surgical resection specimens, and procedural complications were recorded. RESULTS: Thirty-six CEUS-guided musculoskeletal biopsies were performed in 32 patients (mean age 57, range 26-88; 22 males, 10 females). All procedures were performed using 16-gauge biopsy needles, and all procedures provided adequate samples for pathologic analysis as per the final pathology report. Between two and seven core specimens were obtained (mean 3.7). In 30/36 cases (83%), a contrast-enhanced MRI was obtained prior to biopsy, and 10/30 (33%) of these cases showed imaging features suspicious for necrosis. In 15/36 cases, surgical resection was performed, and the core biopsy and surgical resection specimens were concordant in 14/15 cases (93%). One patient noted transient leg discomfort at the time of microbubble bursting. Otherwise, no adverse reactions or procedural complications were observed. CONCLUSION: CEUS is an accurate way to safely target representative areas of soft tissue lesions for biopsy and can be implemented in a busy interventional clinic. Our early experience has shown this to be a promising technique, especially in targeting representative areas of heterogeneous lesions and lesions with areas of suspected necrosis on prior imaging.

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.

Preoperative MRI Shoulder Findings Associated with Clinical Outcome 1 Year after Rotator Cuff Repair.

Background Investigation of the use of preoperative MRI for providing prognostic information regarding clinical outcome following rotator cuff repair has been limited. Purpose To determine whether patients with more severe rotator cuff tears of the shoulder at preoperative MRI have a greater degree of residual pain and disability after rotator cuff repair. Materials and Methods This retrospective study included a cohort of 141 patients who underwent surgical repair of a full-thickness rotator cuff tear at a single institution between April 16, 2012, and September 3, 2015. The mean patient age was 56.8 years, and there were 100 men (mean age, 56.1 years) and 41 women (mean age, 56.3 years). Patients completed the Disabilities of the Arm, Shoulder, and Hand (DASH) survey (lower score indicates less pain and disability) before and 1 year after surgery. One musculoskeletal radiologist blinded to the DASH scores measured the maximal anterior-posterior width and medial-lateral retraction of the rotator cuff tear on the preoperative MRI and assessed tendon degeneration and composite muscle atrophy and fatty infiltration using categorical grading scales (grade 0 indicates no tendon degeneration or muscle atrophy and fatty infiltration, and higher grades indicate incrementally more severe tendon degeneration or muscle atrophy and fatty infiltration). Generalized estimating equation models were used to determine the association between preoperative MRI findings and the postoperative DASH score. Results There was a significant positive association (P < .05) between the measured tear width (estimate, 2.05), measured tear retraction (estimate, 3.52), and tendon degeneration grade (estimate, 1.59) and the postoperative DASH score. There was no significant association (P = .49) between the composite muscle atrophy and fatty infiltration grade (estimate, 0.31) and the postoperative DASH score. Conclusion Patients with larger rotator cuff tears, more tendon retraction, and more severe tendon degeneration have worse clinical outcome scores 1 year after rotator cuff repair. © RSNA, 2019.

Deep Learning Approach for Evaluating Knee MR Images: Achieving High Diagnostic Performance for Cartilage Lesion Detection.

Purpose To determine the feasibility of using a deep learning approach to detect cartilage lesions (including cartilage softening, fibrillation, fissuring, focal defects, diffuse thinning due to cartilage degeneration, and acute cartilage injury) within the knee joint on MR images. Materials and Methods A fully automated deep learning-based cartilage lesion detection system was developed by using segmentation and classification convolutional neural networks (CNNs). Fat-suppressed T2-weighted fast spin-echo MRI data sets of the knee of 175 patients with knee pain were retrospectively analyzed by using the deep learning method. The reference standard for training the CNN classification was the interpretation provided by a fellowship-trained musculoskeletal radiologist of the presence or absence of a cartilage lesion within 17 395 small image patches placed on the articular surfaces of the femur and tibia. Receiver operating curve (ROC) analysis and the κ statistic were used to assess diagnostic performance and intraobserver agreement for detecting cartilage lesions for two individual evaluations performed by the cartilage lesion detection system. Results The sensitivity and specificity of the cartilage lesion detection system at the optimal threshold according to the Youden index were 84.1% and 85.2%, respectively, for evaluation 1 and 80.5% and 87.9%, respectively, for evaluation 2. Areas under the ROC curve were 0.917 and 0.914 for evaluations 1 and 2, respectively, indicating high overall diagnostic accuracy for detecting cartilage lesions. There was good intraobserver agreement between the two individual evaluations, with a κ of 0.76. Conclusion This study demonstrated the feasibility of using a fully automated deep learning-based cartilage lesion detection system to evaluate the articular cartilage of the knee joint with high diagnostic performance and good intraobserver agreement for detecting cartilage degeneration and acute cartilage injury. © RSNA, 2018 Online supplemental material is available for this article .

Evaluation of the Articular Cartilage of the Knee Joint Using an Isotropic Resolution 3D Fast Spin-Echo Sequence With Conventional and Radial Reformatted Images.

OBJECTIVE: The purpose of this study was to determine whether the use of radial reformatted images could improve the diagnostic performance of a 3D fast spin-echo (FSE) sequence for detecting surgically confirmed cartilage lesions within the knee joint. MATERIALS AND METHODS: An MRI examination consisting of five 2D FSE sequences and a sagittal 3D FSE sequence was performed at 3 T on the knee joint of 150 patients who underwent subsequent knee arthroscopy, which included grading of the articular cartilage. Conventional axial, sagittal, and coronal reformatted images and radial reformatted images were created from the 3D FSE source data. Two musculoskeletal radiologists independently used the 2D FSE sequences, the 3D FSE sequence with conventional reformatted images only, and the 3D FSE sequence with both radial and conventional reformatted images at three separate sessions to grade each articular surface of the knee joint. McNemar tests were used to compare diagnostic performance for detecting cartilage lesions using arthroscopy as the reference standard. RESULTS: The 3D FSE sequence with radial and conventional reformatted images had higher sensitivity (p < 0.001) and similar specificity (p = 0.73) to the 2D FSE sequences for detecting cartilage lesions and higher sensitivity (p < 0.001) and specificity (p = 0.002) than the 3D FSE sequence with conventional reformatted images for detecting cartilage lesions. The 3D FSE sequence with conventional reformatted images had similar sensitivity (p = 0.93) and lower specificity (p = 0.005) than did the 2D FSE sequences for detecting cartilage lesions. CONCLUSION: A 3D FSE sequence had improved diagnostic performance compared with 2D FSE sequences for detecting cartilage lesions within the knee joint but only when using both radial and conventional reformatted images for cartilage evaluation.

Evaluation of the articular cartilage of the knee joint: value of adding a T2 mapping sequence to a routine MR imaging protocol.

PURPOSE: To determine whether the addition of a T2 mapping sequence to a routine magnetic resonance (MR) imaging protocol could improve diagnostic performance in the detection of surgically confirmed cartilage lesions within the knee joint at 3.0 T. MATERIALS AND METHODS: This prospective study was approved by the institutional review board, and the requirement to obtain informed consent was waived. The study group consisted of 150 patients (76 male and 74 female patients with an average age of 41.2 and 41.5 years, respectively) who underwent MR imaging and arthroscopy of the knee joint. MR imaging was performed at 3.0 T by using a routine protocol with the addition of a sagittal T2 mapping sequence. Images from all MR examinations were reviewed in consensus by two radiologists before surgery to determine the presence or absence of cartilage lesions on each articular surface, first by using the routine MR protocol alone and then by using the routine MR protocol with T2 maps. Each articular surface was then evaluated at arthroscopy. Generalized estimating equation models were used to compare the sensitivity and specificity of the routine MR imaging protocol with and without T2 maps in the detection of surgically confirmed cartilage lesions. RESULTS: The sensitivity and specificity in the detection of 351 cartilage lesions were 74.6% and 97.8%, respectively, for the routine MR protocol alone and 88.9% and 93.1% for the routine MR protocol with T2 maps. Differences in sensitivity and specificity were statistically significant (P < .001). The addition of T2 maps to the routine MR imaging protocol significantly improved the sensitivity in the detection of 24 areas of cartilage softening (from 4.2% to 62%, P < .001), 41 areas of cartilage fibrillation (from 20% to 66%, P < .001), and 96 superficial partial-thickness cartilage defects (from 71% to 88%, P = .004). CONCLUSION: The addition of a T2 mapping sequence to a routine MR protocol at 3.0 T improved sensitivity in the detection of cartilage lesions within the knee joint from 74.6% to 88.9%, with only a small reduction in specificity. The greatest improvement in sensitivity with use of the T2 maps was in the identification of early cartilage degeneration.

MR Appearance and Clinical Significance of Changes in the Hip Muscles and Iliopsoas Tendon After Arthroscopic Iliopsoas Tenotomy in Symptomatic Patients.

BACKGROUND: Iliopsoas tenotomy is a treatment for snapping hip. Does this surgical procedure change the surrounding muscle and tendon anatomy? QUESTIONS/PURPOSES: This study seeks to evaluate the changes in the MR appearance of the hip muscles and iliopsoas tendon in patients following arthroscopic iliopsoas tenotomy. METHODS: One hundred sixty-nine consecutive adults were evaluated after iliopsoas tenotomy at the lesser trochanter. Each MR exam was evaluated independently by three radiologists for muscle edema, atrophy (grade 0-4), compensatory hypertrophy, signal within the iliopsoas tendon (increased on T1 or T2 sequences), and iliopsoas tendon morphology (distorted or disrupted) above, at, and below the iliopectineal eminence. A finding was considered positive if reported by two or three of the radiologists. RESULTS: Twenty subjects met the inclusion criteria. Muscle edema was present in 15% (3/20) of subjects within the iliacus, psoas, and quadratus femoris. Atrophy was observed in the following muscles: iliacus 85% (17/20), psoas 75% (15/20), quadratus femoris 10% (2/20), rectus femoris 5% (1/20), vastus lateralis 5% (1/20), and gluteus maximus 25% (5/20). There was no compensatory hypertrophy. Ninety percent (18/20) had increased T1 and 10% (2/20) had increased T2 signal within the iliopsoas tendon. Thirty-five percent (7/20) of the iliopsoas tendons was disrupted and 85% (17/20) was distorted, most commonly below the iliopectineal eminence. CONCLUSION: The majority of postoperative symptomatic patients has atrophy of the iliacus and psoas muscles and distortion and disruption of the iliopsoas tendon and should be recognized as a normal imaging appearance following iliopsoas tendon release.

Imaging appearance of the normal and partially torn ligamentum teres on hip MR arthrography.

OBJECTIVE: The purpose of this study was to evaluate the MR arthrographic appearance of the normal and partially torn ligament teres and to determine if there are imaging criteria for diagnosing partial tears of the ligamentum teres. MATERIALS AND METHODS: One hundred sixteen patients underwent preoperative MR arthrography and hip arthroscopy. Each MR examination was evaluated independently by two musculoskeletal radiologists for the following: size and width of the ligamentum teres in the proximal, mid, and distal thirds of the ligamentum teres; overall length of the ligamentum; number of bundles (1-3); signal intensity (SI) within the ligamentum teres (low, intermediate, high); ligamentum teres fibers (normal, attenuated, thickened, wavy); ligamentum teres integrity (not torn, degenerated, frayed, partial tear); and femoral head edema at the ligamentum teres origin. Statistical analysis was performed using the Kruskal-Wallis rank sum test and Fisher exact test. RESULTS: Twelve of 116 (10%) subjects had partial ligamentum teres tears. One hundred four subjects had an intact ligamentum teres. The average size and width of the intact ligamentum teres was 12.6 × 4.38, 14.9 × 3.5, and 14.3 × 2.7 mm for proximal, mid, and distal, respectively, with an overall length 27.7 mm. It was most common to visualize two bundles in the proximal portion of the normal ligamentum teres (61 and 64/116). Low, intermediate, and high SI was common on all pulse sequences in normal and partially torn ligamentum teres for both readers (p = 0.33-0.84). For reader 1, there was no statistical difference between ligamentum teres fiber appearance in partial tears (p = 0.20). In contrast, reader 2 found partial tears associated with attenuated and wavy appearance (p = 0.003). Reader 1 diagnosed five of 12 (42%), and reader 2 diagnosed eight of 12 (67%) of the partial ligamentum teres tears (p = 0.47 and p = 0.0004). Edema of the femoral ligamentum teres origin was not associated with partial tears (p = 0.33-0.86). Retrospective review revealed that six partial tears had intra substance linear high SI on T2 images and peripheral irregularity, whereas four other tears had high SI within the ligamentum teres fibers without peripheral irregularity. CONCLUSION: The intact and partially torn ligamentum teres can have similar imaging findings on MR arthrography, making the diagnosis of partial ligamentum teres tears difficult. High SI within the substance of the fibers and irregularity suggest partial tearing; however, further research is warranted.

Labral injuries due to iliopsoas impingement: can they be diagnosed on MR arthrography?

OBJECTIVE: Iliopsoas impingement is a new arthroscopic diagnosis that refers to an anterior labral injury caused by the iliopsoas tendon. Currently, there are no preoperative criteria to establish the diagnosis of iliopsoas impingement. The goal of this study was to determine whether there are imaging criteria that would identify iliopsoas impingement on preoperative MR arthrography. MATERIALS AND METHODS: This study compared the preoperative MR arthrograms of 23 patients who had iliopsoas impingement diagnosed at hip arthroscopy with the arthrograms of 24 patients who did not have iliopsoas impingement found at hip arthroscopy. All of the arthroscopies were performed by a single orthopedic hip surgeon. In all cases of impingement, there was an isolated injury to the labrum at the 3-o'clock position. All were treated by arthroscopic iliopsoas tenotomy performed at the labral level. The MR examinations of the 47 patients were evaluated independently by two musculoskeletal radiologists who were blinded to the diagnosis. The following characteristics of the iliopsoas tendon at the level of the anterior labrum were evaluated: lateral dip, increased signal intensity (SI) between the iliopsoas tendon and labrum, irregularity of the deep margin of the iliopsoas tendon, edema within the iliopsoas tendon or capsule at the 3-o'clock position, presence of a labral tear at the 3-o'clock position, dimensions of the iliopsoas tendon, and location of iliopsoas tendon as it passed the labrum. Statistical analysis was performed using the Kruskal Wallis test, Fisher exact test, and Cohen kappa. Values for p less than 0.05 were considered significant. RESULTS: Nineteen women (mean age, 35 years) and four men (mean age, 36 years) had central iliopsoas impingement. Sixteen women (mean age, 38 years) and eight men (mean age, 35 years) did not have central iliopsoas impingement (p=0.318). For the impingement and nonimpingement groups, lateral dip of the iliopsoas tendon was seen in 15 of 23 (65%) and 17 of 24 (71%) for reader 1 and 18 of 23 (78%) and 11 of 24 (46%) for reader 2, respectively (p=0.76 and 0.036, respectively). There was no difference between the groups for increased SI between the iliopsoas tendon and labrum (p=0.38 and 0.82, respectively), irregular deep margin of the iliopsoas tendon (p=0.61 and 0.35, respectively), thickness of the iliopsoas tendon (p=0.33), or tendon or capsule edema (p=0.37 and 0.77, respectively). Reader 1 found 20 of 23 and reader 2 18 of 23 labral tears at the 3-o'clock position in the iliopsoas impingement group, with 13 of 24 and 10 of 24 in the non-iliopsoas impingement group respectively (p=0.024 and 0.017, respectively). The combined iliopsoas tendon width for both readers was 10.2 mm (range, 8.1-14.3 mm) in women and 11.9 mm (range, 11.1-13.4 mm) in men in the iliopsoas impingement group (p=0.0285), and 11.0 mm (range, 9.0-12.6 mm) for women and 11.8 mm (range, 8.7-15.1 mm) for men in the non-iliopsoas impingement group (p=0.159). The iliopsoas tendon most commonly crossed the labrum at the 3-o'clock position in both groups (p=0.83-0.17). CONCLUSION: An acetabular labral tear at the 3-o'clock position should suggest the diagnosis of iliopsoas impingement.

MR arthrographic appearance of the postoperative acetabular labrum in patients with suspected recurrent labral tears.

OBJECTIVE: The objective of our study was to evaluate the MR arthrographic appearance of the acetabular labrum in patients with a suspected recurrent acetabular labral tear after previous arthroscopic resection of a labral tear. CONCLUSION: The labrum after excision will appear shortened on MR arthrography. A recurrent labral tear can be diagnosed by the identification on MR arthrography of a new line to the labral surface, an enlarged and distorted labrum, or a new paralabral cyst.

MR arthrography of the hip: comparison of IDEAL-SPGR volume sequence to standard MR sequences in the detection and grading of cartilage lesions.

PURPOSE: To compare the diagnostic performance of iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL)-spoiled gradient-recalled echo (SPGR) with that of standard magnetic resonance (MR) arthrography sequences for detecting and grading cartilage lesions within the hip joint during MR arthrography. MATERIALS AND METHODS: Following institutional review board approval, 67 consecutive hip MR arthrograms were retrospectively reviewed independently by three musculoskeletal radiologists and one musculoskeletal fellow. IDEAL-SPGR images and the two-dimensional images, the latter from the routine MR arthrography protocol, were evaluated at separate sittings to grade each articular surface of the hip joint. By using arthroscopy as the reference standard, the sensitivity and specificity of the two techniques for detecting and grading cartilage lesions were determined. The McNemar test was used to compare diagnostic performance. Interreader agreement was calculated using Fleiss κ values. RESULTS: For all readers and surfaces combined, the sensitivity and specificity for detecting cartilage lesions was 74% and 77%, respectively, for IDEAL-SPGR and 70% and 84%, respectively, for the routine MR arthrography protocol. IDEAL-SPGR had similar sensitivity (P = .12) to and significantly lower specificity (P < .001) than the routine MR arthrography protocol for depicting cartilage lesions. When analyzing the differences in sensitivity and specificity by reader, the two readers who had experience with IDEAL-SPGR had no significant difference in sensitivity and specificity for detecting cartilage lesions between the two sequences. For all readers and surfaces combined, IDEAL-SPGR had a higher accuracy in correctly grading cartilage lesion (P = .012-.013). Interobserver agreement for detecting cartilage lesions did not differ between the two techniques. CONCLUSION: IDEAL-SPGR had similar sensitivity and significantly lower specificity for detecting cartilage lesions and higher accuracy for grading cartilage lesions than did a routine MR arthrography protocol; the lower specificity of IDEAL-SPGR for detecting cartilage lesions was not seen in experienced readers.

MR imaging of early hip joint degeneration.

MR imaging is one of the most commonly used imaging techniques to evaluate patients with hip pain. Intra-articular abnormalities of the hip joint are better assessed with recent advances in MR imaging technology, such as high-field strength scanners, improved coils, and more signal-to-noise ratio-efficient sequences. This article discusses the causes of early hip joint degeneration and the current use of morphologic and physiologic MR imaging techniques for evaluating the articular cartilage of the hip joint. The article also discusses the role of MR arthrography in clinical cartilage imaging.

Hip pain referral patterns in patients with labral tears: analysis based on intra-articular anesthetic injections, hip arthroscopy, and a new pain "circle" diagram.

BACKGROUND: Fluoroscopically guided intra-articular (FGIA) anesthetic hip joint injections have been used to determine whether the hip joint is the source of a patient's hip pain. However, there have been no reports documenting the efficacy of their use for defining the pain referral patterns (PRPs) of patients with labral tears. The aim of this study was to determine the PRPs of patients with labral tears and evaluate a new pain "circle" diagram (PCD) developed for this analysis. METHODS: Fifty-two patients were evaluated at our institution who had: 1) a preoperative FGIA anesthetic hip joint injection; 2) completed our PCD and a visual analog pain scale pre- and postinjection; 3) significant (≥ 80%) pain reduction after their FGIA injection; and 4) a labral tear and minimal (≤ grade II) degenerative joint disease, as documented by hip arthroscopy. The PCD had circles in which patients put an "X" in to indicate pain in the following locations: anterior superior spine, lateral peritrochanteric area, central groin, symphysis pubis, proximal inner thigh, anterior thigh, posterior iliac crest, sacroiliac joint, sciatic notch, and ischial tuberosity. RESULTS: Based on the percentage of patients with significant (≥ 80%) pain reduction after administration of FGIA, 2 areas demonstrated substantially more and consistent presence of pain, which improved after injection. These were the central groin (P < 0.001) and the lateral peritrochanteric area (P = 0.02). CONCLUSION: The most common locations of pain were the central groin and the lateral peritrochanteric area. The least common were the ischial tuberosity and the anterior thigh, which are 2 areas often associated with osteoarthritis of the hip. The use of the PCD combined with an FGIA anesthetic injection may help physicians reconcile the expectations of those patients with labral tears who believe that hip arthroscopy will treat their multiple areas of "hip" pain.