Peripheral tear of the triangular fibrocartilage complex: diagnostic accuracy of magnetic resonance imaging and diagnostic performance of the primary and secondary signs.

OBJECTIVE: This study is to assess the diagnostic performance of magnetic resonance imaging (MRI) findings for type 1B triangular fibrocartilage complex (TFCC) tear of the wrist. MATERIALS AND METHODS: This study retrospectively enrolled 78 patients to examine the diagnostic performance of preoperative MRI examinations in patients with type 1B TFCC tears. Thirty-nine participants had confirmed type 1B TFCC tear. The control group included 39 patients who were randomly selected from 1157 patients who underwent MRI for wrist pain. Both groups underwent a review of 19 MRI findings by two independent radiologists, and the correlation between each diagnostic finding and type 1B TFCC tear was assessed using the chi-squared test. The 19 MRI findings comprised eight primary signs of abnormalities in the distal or proximal lamina, in conjunction with 11 secondary signs suggestive of abnormalities in the surrounding structures. RESULTS: The TFCC tear group demonstrated a significantly higher incidence of two primary MRI signs, i.e., fiber discontinuity and signal alteration in the distal lamina, as observed by both readers (R1, 74.4% vs. 38.5%, p = 0.003, and 87.2% vs. 43.6%, p < 0.001; R2, 74.4% vs. 35.9%, p = 0.001, and 87.2% vs. 53.8%, p < 0.003, respectively). Reader 2 identified a higher prevalence of two additional primary MRI signs: fiber discontinuity and signal alteration in the proximal lamina (all p < 0.05). None of the 11 secondary MRI signs demonstrated statistically significant associations with type 1B TFCC. CONCLUSION: MRI manifestations of fiber discontinuity and signal alteration in the distal lamina may provide predictive markers for type 1B TFCC wrist tear.

Dual-layer spectral detector CT arthrography of the shoulder: assessment of image quality and value in differentiating calcium from iodine.

BACKGROUND: Dual-layer spectral detector computed tomography (DLCT) may potentially improve CT arthrography through enhanced image quality and analysis of the chemical composition of tissue. PURPOSE: To evaluate the image quality of monoenergetic reconstructions from DLCT arthrography of the shoulder and assess the additional diagnostic value in differentiating calcium from iodine. MATERIAL AND METHODS: Images from consecutive shoulder DLCT arthrography examinations performed between December 2016 and February 2018 were retrospectively reviewed for hyperattenuating lesions within the labrum and tendons. The mean attenuation of the target lesion, noise, contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR) of the virtual monoenergetic images obtained at 40-200 keV were compared with conventional 140-kVp images. Two evaluators independently classified each target lesion as contrast media or calcification, without and with DLCT spectral data. Receiver operating curve (ROC) analysis was performed to assess the diagnostic performance of shoulder DLCT arthrography, without and with the aid of spectral data. RESULTS: The study included 20 target lesions (18 DLCT arthrography examinations of 17 patients). The SNRs of the monoenergetic images at 40-60 keV were significantly higher than those of conventional images (P < 0.05). The CNRs of the monoenergetic images at 40-70 keV were significantly higher than those of conventional images (P < 0.001). The ability to differentiate calcium from iodine, without and with DLCT spectral data, did not significantly differ (P = 0.441 and P = 0.257 for reviewers 1 and 2, respectively). CONCLUSION: DLCT had no additive value in differentiating calcium from iodine in small, hyperattenuating lesions in the labrum and tendons.

Utilization of Noncontrast Magnetic Resonance Lymphangiography for Selection of Effective Surgical Method in Breast Cancer-Related Lymphedema.

Background and Objectives: When considering surgery for patients with breast cancer-related lymphedema (BCRL), it is crucial to determine which surgery will be most effective for the patient and establish the indications for each surgery. Our study retrospectively compared the results of preoperative noncontrast MR lymphangiography (NMRL) performed on the lymphedematous limb of patients before surgery, with the aim of analyzing whether preoperative NMRL can be used as a criterion for determining the type of surgery. Materials and Methods: From January 2020 to June 2022, a total of 138 patients with lymphedema underwent surgery at Seoul National University Bundang Hospital. All patients underwent preoperative NMRL imaging and were classified into stages 1-3 based on the MRI severity index using the authors' previous reference. Three types of surgery, LVA, LVA + liposuction, and LVA + VLNT, were conducted on all patients. The effectiveness of the surgery was evaluated one year postoperatively using the interlimb volume difference before and after surgery, the fluid volume of the edematous limb measured by bioimpedance spectroscopy, and the subjective satisfaction of the patients through the Lymph Q questionnaire. Results: In this study, out of a total of 138 patients, 26 (19%) were MRI stage 1, 62 (45%) were stage 2, and 50 (36%) were stage 3. Of the 83 patients who underwent LVA surgery, the greatest decrease in interlimb volume difference was observed in stage 2 patients, and subjective satisfaction was also the most effective in stage 2. In the case of LVA + liposuction patients, a significant volume decrease and a high satisfaction were observed in stage 3 patients. In the case of LVA + VLNT patients, there was no difference in volume decrease according to the stage, but a greater decrease in body fluid volume was observed as the MRI severity index score increased through BIA. Conclusions: In conclusion, this study demonstrates that NMRL imaging is a useful modality for determining the most effective surgical method and predicting the surgical outcome in patients with lymphedema. This highlights the importance of using NMRL in the treatment planning of lymphedema patients.

Effectiveness of epidural steroid injection in patients with lumbar herniated intervertebral disc under a "wait-and-see" policy.

BACKGROUND: There are no consensus and guidelines on the optimal interval of repeat epidural steroid injections (ESI) for patients with lumbar herniated intervertebral disc (HIVD) who respond to initial ESI. PURPOSE: To evaluate the effectiveness of ESI in patients with HIVD under a "wait-and-see" policy, i.e. as-needed injections not on a predetermined schedule. MATERIAL AND METHODS: A total of 592 patients with lumbar HIVD received spine injections between January and December 2017. After excluding patients with excellent (no pain) or poor (>70% residual symptoms) response in the two- or three-week pain assessment, the data of 141 responders were analyzed (60 men, 73 women; age = 50.55±17.25 years). We divided patients into wait-and-see (n=124) and early repeat-ESI (n=17) groups, who received repeat ESIs within three weeks. Evaluations of characteristics and outcomes were performed with the chi-square test or independent Student's t-test. RESULTS: Six patients (4.8%) in the wait-and-see group and 1 (5.9%) in the early repeat-ESI group underwent operation within one year (P=0.85). A mean of 1.52±0.82 ESIs was performed in the wait-and-see and a mean of 2.29±0.47 ESIs in the early repeat-ESI group over one year (P<0.001). The time interval between the first and second ESIs was longer in the wait-and-see group than in the early repeat-ESI group (97.15 vs. 15.47 days, P<0.001). Seventy-eight patients (62.9%) in the wait-and-see group could control their pain with a single ESI. CONCLUSION: A "wait-and-see" policy could be an effective pain management option for patients with lumbar HIVD who respond to initial ESI.

Morphological changes in the superficial medial collateral ligament on knee MR imaging: association with medial meniscal extrusion and posterior root medial meniscus abnormality.

OBJECTIVE: To assess the association between morphological changes in the superficial medial collateral ligament and meniscal extrusion with medial meniscus posterior root tear. MATERIALS AND METHODS: From January 1, 2018, to December 31, 2019, 124 patients who underwent knee MRI within 90 days prior to knee surgery and whose medial meniscus surgically proved intact, with posterior root tear or posterior horn tear, were enrolled. Two radiologists who were blinded to the surgical results assessed the morphological changes in the superficial medial collateral ligament, including thickness, bowing angle, and presence of signal intensity alteration, and medial meniscus extrusion, according to the presence of tears in the posterior root of the medial meniscus or posterior horn of the medial meniscus using the chi-square test, one-way ANOVA, and Cohen's kappa test. RESULTS: Thirty-six posterior root tears, 31 posterior horn tears, and 57 intact medial menisci were observed surgically. The mean values of thickness showed no significant differences among the three groups. The bowing angle was significantly higher in the posterior root tear than in the posterior horn tear (reader 1 = 0.001, reader 2 = 0.002) and normal meniscus groups (readers 1 and 2 < 0.001). The percentage of superficial medial collateral ligament signal intensity alteration and meniscal extrusion was highest in the group with posterior root of the medial meniscus tear (80.6% and 94.4%, respectively) and lowest in the group with normal medial meniscus (17.5% and 10.5%, respectively). CONCLUSION: Morphological changes in the superficial medial collateral ligament and meniscal extrusion were associated with medial meniscus posterior root tears.

The 2021 Association Research Circulation Osseous Classification for Early-Stage Osteonecrosis of the Femoral Head to Computed Tomography-Based Study.

BACKGROUND: The Association Research Circulation Osseous developed a novel classification for early-stage (precollapse) osteonecrosis of the femoral head (ONFH). We hypothesized that the novel classification is more reliable and valid when compared to previous 3 classifications: Steinberg, modified Kerboul, and Japanese Investigation Committee classifications. METHODS: In the novel classification, necrotic lesions were classified into 3 types: type 1 is a small lesion, where the lateral necrotic margin is medial to the femoral head apex; type 2 is a medium-sized lesion, with the lateral necrotic margin being between the femoral head apex and the lateral acetabular edge; and type 3 is a large lesion, which extends outside the lateral acetabular edge. In a derivation cohort of 40 early-stage osteonecrotic hips based on computed tomography imaging, reliabilities were evaluated using kappa coefficients, and validities to predict future femoral head collapse by chi-squared tests and receiver operating characteristic curve analyses. The predictability for future collapse was also evaluated in a validation cohort of 104 early-stage ONFH. RESULTS: In the derivation cohort, interobserver reliability (k = 0.545) and intraobserver agreement (63%-100%) of the novel method were higher than the other 3 classifications. The novel classification system was best able to predict future collapse (P < .05) and had the best discrimination between non-progressors and progressors in both the derivation cohort (area under the curve = 0.692 [0.522-0.863], P < .05) and the validation cohort (area under the curve = 0.742 [0.644-0.841], P = 2.46 × 10-5). CONCLUSION: This novel classification is a highly reliable and valid method of those examined. Association Research Circulation Osseous recommends using this method as a unified classification for early-stage ONFH. LEVEL OF EVIDENCE: Level III, diagnostic study.

Evaluating subscapularis tendon tears on axillary lateral radiographs using deep learning.

OBJECTIVE: To develop a deep learning algorithm capable of evaluating subscapularis tendon (SSC) tears based on axillary lateral shoulder radiography. METHODS: A total of 2,779 axillary lateral shoulder radiographs (performed between February 2010 and December 2018) and the patients' corresponding clinical information (age, sex, dominant side, history of trauma, and degree of pain) were used to develop the deep learning algorithm. The radiographs were labeled based on arthroscopic findings, with the output being the probability of an SSC tear exceeding 50% of the tendon's thickness. The algorithm's performance was evaluated by determining the area under the receiver operating characteristic curve (AUC), sensitivity, specificity, negative predictive value (NPV), and negative likelihood ratio (LR-) at a predefined high-sensitivity cutoff point. Two different test sets were used, with radiographs obtained between January and December 2019; Test Set 1 used arthroscopic findings as the reference standard (n = 340), whereas Test Set 2 used MRI findings as the reference standard (n = 627). RESULTS: The AUCs were 0.83 (95% confidence interval, 0.79-0.88) and 0.82 (95% confidence interval, 0.79-0.86) for Test Sets 1 and 2, respectively. At the high-sensitivity cutoff point, the sensitivity, NPV, and LR- were 91.4%, 90.4%, and 0.21 in Test Set 1, and 90.2%, 89.5%, and 0.21 in Test Set 2, respectively. Gradient-weighted Class Activation Mapping identified the subscapularis insertion site at the lesser tuberosity as the most sensitive region. CONCLUSION: Our deep learning algorithm is capable of assessing SSC tears based on changes at the lesser tuberosity on axillary lateral radiographs with moderate accuracy. KEY POINTS: • We have developed a deep learning algorithm capable of assessing SSC tears based on changes at the lesser tuberosity on axillary lateral radiographs and previous clinical data with moderate accuracy. • Our deep learning algorithm could be used as an objective method to initially assess SSC integrity and to identify those who would and would not benefit from further investigation or treatment.

Predicting the clinically significant subscapularis tendon tear: malposition and tear of the long head of the biceps tendon on shoulder magnetic resonance imaging.

BACKGROUND: The diagnostic accuracy of magnetic resonance imaging (MRI) is low for detecting a subscapularis tendon tear. PURPOSE: To identify MRI findings that may predict the presence of a clinically significant subscapularis tendon tear requiring surgical repair. MATERIAL AND METHODS: We reviewed shoulder MR images of patients who had undergone arthroscopic rotator cuff repair at our institution between June 2018 and May 2019. Patients were divided into two groups: the study group (n = 51), with an intermediate- to high-grade partial thickness tear of the subscapularis tendon suspected on preoperative MRI and intermediate or higher grade of the tendon tear proven on arthroscopy; and the control group (n = 18), with an intermediate- to high-grade partial thickness tear of the subscapularis tendon suspected on preoperative MRI but no tear or low-grade partial thickness tear of the tendon shown on arthroscopy. Preoperative MR images were retrospectively evaluated by two readers for the size of the subscapularis tendon tear, bone reactions at the lesser tuberosity, and long head of the biceps tendon (LHBT) pathology. RESULTS: The subscapularis tendon tear measured by reader 2 was larger in the study group than in the control group. The prevalence of a tear (P = 0.006 for reader 1; P = 0.011 for reader 2) and malposition (P < 0.001 for both readers) of the LHBT were significantly greater in the study group. CONCLUSION: A tear and malposition of the LHBT on MR images may predict the presence of a clinically significant subscapularis tendon tear.

Magnetic resonance imaging evaluation of patients with clinically diagnosed medial Epicondylitis.

OBJECTIVE: We evaluated magnetic resonance imaging (MRI) findings in patients with clinically diagnosed medial epicondylitis (ME) and determined whether any of the MRI findings correlated with the follow-up pain level after nonoperative treatment. MATERIALS AND METHODS: We retrospectively reviewed 83 patients who had undergone elbow MRI examinations for clinically diagnosed ME and who were followed-up for more than 6 months. Five categories of MRI findings were selected for qualitative grading: common flexor tendon (CFT) origin signal changes, ulnar collateral ligament (UCL) insufficiency, ulnar neuritis, bony changes of the medial epicondyle, and calcification. The mean follow-up after MRI examination was 21 months. We performed multivariate regression analysis to analyze whether any of these MRI findings were associated with the follow-up pain level after nonoperative treatment. RESULTS: Positive MRI findings included CFT origin signal changes (66%), ulnar neuritis (40%), UCL insufficiency (30%), calcification (27%), and bony changes (18%). Multivariate analysis indicated that CFT origin signal changes were independently associated with the follow-up pain level (ß = 3.387; p = 0.004). CONCLUSION: In patients with clinically diagnosed ME, MRI demonstrated diverse abnormal findings in the CFT origin, ulnar collateral ligament, ulnar nerve, and bone. Among the findings, the severity CFT origin signal changes, which indicates the severity of tendon degeneration in ME, was associated with the follow-up pain level. This information can be helpful in consulting on the prognosis of nonoperative treatment in patients with clinically diagnosed ME.

Intra-articular facet joint steroid injection-related adverse events encountered during 11,980 procedures.

OBJECTIVES: To analyze the incidence and characteristics of intra-articular facet joint injection (FJI)-related adverse events requiring hospitalization and emergency room visits. METHODS: From January 2007 to December 2017, a total of 11,980 FJI procedures in 6066 patients (mean age 66.8 years, range 15-97 years, M:F = 2004:4062) were performed in our department. Of these, we retrospectively reviewed 489 cases in 432 patients who were hospitalized or visited the emergency room within a month of FJI. FJI-related adverse events were classified as procedure-related complications, drug-related systemic events, or uncertain etiology events, on the basis of consensus of two spine radiologists. This is a descriptive study without statistical analysis. RESULTS: There were 101 FJI-related adverse event cases in 99 patients (mean age 71.8 years, range 39-97 years, M:F = 39:60). The overall incidence of FJI-related adverse events was 0.84% (101/11,980) per case and 1.63% (99/6066) per patient. The incidence of procedure-related complications and drug-related systemic adverse events was 0.07% (8/11,980) and 0.15% (18/11,980), respectively; the rate of uncertain etiology events was 0.63% (75/11,980). All eight procedure-related complication cases involved major complications. There are seven cases of infectious spondylitis and one was progression of systemic aspergillosis to the spine. One patient died of an uncontrolled infection with infective endocarditis, and two patients experienced partial recovery with neurological sequelae. CONCLUSIONS: The overall incidence of FJI-related adverse events is low, and procedure-related major complications are rare without dural puncture or epidural hematoma. Nevertheless, infection can occur, resulting in serious outcomes. KEY POINTS: • The incidence of FJI-related adverse events requiring hospitalization or ER visit was 0.84%. • The incidence of major procedure-related complications was 0.07%. • All major complications were associated with infection and there were no cases of epidural hematoma.

Ruling out rotator cuff tear in shoulder radiograph series using deep learning: redefining the role of conventional radiograph.

OBJECTIVE: To develop a deep learning algorithm that can rule out significant rotator cuff tear based on conventional shoulder radiographs in patients suspected of rotator cuff tear. METHODS: The algorithm was developed using 6793 shoulder radiograph series performed between January 2015 and June 2018, which were labeled based on ultrasound or MRI conducted within 90 days, and clinical information (age, sex, dominant side, history of trauma, degree of pain). The output was the probability of significant rotator cuff tear (supraspinatus/infraspinatus complex tear with > 50% of tendon thickness). An operating point corresponding to sensitivity of 98% was set to achieve high negative predictive value (NPV) and low negative likelihood ratio (LR-). The performance of the algorithm was tested with 1095 radiograph series performed between July and December 2018. Subgroup analysis using Fisher's exact test was performed to identify factors (clinical information, radiography vendor, advanced imaging modality) associated with negative test results and NPV. RESULTS: Sensitivity, NPV, and LR- were 97.3%, 96.6%, and 0.06, respectively. The deep learning algorithm could rule out significant rotator cuff tear in about 30% of patients suspected of rotator cuff tear. The subgroup analysis showed that age < 60 years (p < 0.001), non-dominant side (p < 0.001), absence of trauma history (p = 0.001), and ultrasound examination (p < 0.001) were associated with negative test results. NPVs were higher in patients with age < 60 years (p = 0.024) and examined with ultrasound (p < 0.001). CONCLUSION: The deep learning algorithm could accurately rule out significant rotator cuff tear based on shoulder radiographs. KEY POINTS: • The deep learning algorithm can rule out significant rotator cuff tear with a negative likelihood ratio of 0.06 and a negative predictive value of 96.6%. • The deep learning algorithm can guide patients with significant rotator cuff tear to additional shoulder ultrasound or MRI with a sensitivity of 97.3%. • The deep learning algorithm could rule out significant rotator cuff tear in about 30% of patients with clinically suspected rotator cuff tear.

Prevalence and distribution of MRI abnormalities in the articular cartilage and supporting ligaments in patients with early clinical stage first carpometacarpal joint osteoarthritis.

OBJECTIVE: We used magnetic resonance imaging (MRI) to evaluate where articular degeneration begins and which ligaments are most often involved in the early clinical stage first carpometacarpal joint (CMCJ-1) osteoarthritis. MATERIALS AND METHODS: We retrospectively analyzed the MRI findings of 26 patients with early clinical stage CMCJ-1 osteoarthritis and no radiologic abnormalities and 19 control patients without CMCJ-1 pain or osteoarthritis who underwent MRI for dorsal or ulnar wrist pain. Two observers blinded to group and clinical findings independently assessed the presence of chondral defects in four quadrants of the CMCJ-1: volar-ulnar (VU), volar-radial (VR), dorso-ulnar (DU), and dorso-radial (DR). The integrity of the four major ligaments of the CMCJ-1, i.e., the anterior oblique ligament (AOL), the intermetacarpal ligament (IML), the posterior oblique ligament (POL), and the dorsal radial ligament (DRL), was assessed. The observer reliability was analyzed using Cohen's kappa coefficient. The prevalence of cartilage lesions and ligament abnormalities in the osteoarthritic and control patients was compared using Fisher's exact test. RESULTS: Cartilage lesions were significantly more common in the VU quadrant of the trapezium in the osteoarthritic patients than in the control patients (17/26 vs. 2/19; P = 0.002). AOL abnormalities were more common in the osteoarthritic patients than in the control patients (14/26 vs. 3/19; P = 0.009). CONCLUSION: The MRI findings of early clinical stage CMCJ-1 osteoarthritis commonly demonstrated cartilage lesions in the VU quadrant of the trapezium and ligament abnormalities in the AOL.

Association of meniscal flounce in the knee with the pattern and location of meniscal tear, concomitant ligamentous injury, amount of knee joint effusion, and flexion and rotation angles: a magnetic resonance evaluation.

OBJECTIVE: To determine the association of meniscal flounce with the pattern and location of the meniscal tear, concomitant ligamentous injury, amount of knee joint effusion, and flexion and rotation angles. MATERIALS AND METHODS: A total of 283 knees of 280 patients were retrospectively reviewed over a 9-month period. Thirty-one magnetic resonance images of patients with meniscal flounce were compared with those of age- and sex-matched control group (n = 62) without meniscal flounce. The presence of meniscal tear was evaluated and, if present, its location and pattern were recorded. The amount of joint effusion was graded, and the joint angle was measured. The Fisher's exact, Cochran-Armitage trend, and t tests were performed to compare the findings between the two groups. The decision tree analysis was employed to determine the most significant factor of meniscal flounce. RESULTS: Meniscal flounce was present in 11.0% (31/283) of the adult population. Approximately 80.6% of meniscal flounce occurred in the torn medial menisci. The presence of meniscal flounce was significantly associated with tears at the body (p = 0.007), posterior horn (p = 0.001), and meniscocapsular junction (p = 0.002) of the medial meniscus. The decision tree analysis revealed that the posterior horn tear of the medial meniscus was the most significant predictor of meniscal flounce. CONCLUSION: The most significant factor associated with meniscal flounce is tear at the posterior horn of the medial meniscus, followed by tear at the meniscocapsular junction.

Distinguishing necrotizing from non-necrotizing fasciitis: a new predictive scoring integrating MRI in the LRINEC score.

OBJECTIVES: To develop and validate a scoring system integrating MRI and laboratory findings to differentiate necrotizing fasciitis (NF) from non-necrotizing fasciitis (non-NF). METHODS: This retrospective study included 144 subjects who underwent surgery in one of three tertiary referral centers for NF or cellulitis with non-NF. The development cohort consisted of 96 subjects (NF = 47; non-NF = 49) from one center, and the validation cohort consisted of 48 subjects (NF = 23; cellulitis with non-NF = 25) from two different centers. The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) scoring system and five MRI findings (thickening of the intermuscular deep fascia ≥ 3 mm, extensive involvement of the deep fascia, multi-compartmental involvement in one extremity, presence of gas, and contrast-enhancement pattern) were included in univariate and multivariate logistic regression analysis to identify independent predictors of NF. An additive scoring system was developed using the coefficients of the final regression model. Model performance was assessed for discrimination and calibration. The scoring system was externally validated. RESULT: The final scoring system consisted of three variables: thickening of the deep fascia ≥ 3 mm, multi-compartmental involvement, and LRINEC score. The new predictive model showed improved performance (area under the receiver operating characteristic curve [AUC], 0.862; positive and negative predictive values, 82% and 79%, respectively), compared with the LRINEC score alone (0.814, 77% and 67%, respectively). The model also showed good discrimination with the external validation dataset (AUC, 0.933). CONCLUSIONS: Differentiation of NF from severe cellulitis with non-NF can be achieved with the new predictive scoring system. KEY POINTS: • The new predictive scoring system integrating two MRI findings with the LRINEC score can help in the differentiation of necrotizing fasciitis from severe cellulitis with non-necrotizing fasciitis. • Thickening of the deep fascia ≥ 3 mm and multi-compartmental involvement were the most important MRI findings for the differentiation.

Performance of a Deep Learning Algorithm in Detecting Osteonecrosis of the Femoral Head on Digital Radiography: A Comparison With Assessments by Radiologists.

OBJECTIVE. The objective of our study was to compare the sensitivity of a deep learning (DL) algorithm with the assessments by radiologists in diagnosing osteonecrosis of the femoral head (ONFH) using digital radiography. MATERIALS AND METHODS. We performed a two-center, retrospective, noninferiority study of consecutive patients (≥ 16 years old) with a diagnosis of ONFH based on MR images. We investigated the following four datasets of unilaterally cropped hip anteroposterior radiographs: training (n = 1346), internal validation (n = 148), temporal external test (n = 148), and geographic external test (n = 250). Diagnostic performance was measured for a DL algorithm, a less experienced radiologist, and an experienced radiologist. Noninferiority analyses for sensitivity were performed for the DL algorithm and both radiologists. Subgroup analysis for precollapse and postcollapse ONFH was done. RESULTS. Overall, 1892 hips (1037 diseased and 855 normal) were included. Sensitivity and specificity for the temporal external test set were 84.8% and 91.3% for the DL algorithm, 77.6% and 100.0% for the less experienced radiologist, and 82.4% and 100.0% for the experienced radiologist. Sensitivity and specificity for the geographic external test set were 75.2% and 97.2% for the DL algorithm, 77.6% and 75.0% for the less experienced radiologist, and 78.0% and 86.1% for the experienced radiologist. The sensitivity of the DL algorithm was noninferior to that of the assessments by both radiologists. The DL algorithm was more sensitive for precollapse ONFH than the assessment by the less experienced radiologist in the temporal external test set (75.9% vs 57.4%; 95% CI of the difference, 4.5-32.8%). CONCLUSION. The sensitivity of the DL algorithm for diagnosing ONFH using digital radiography was noninferior to that of both less experienced and experienced radiologist assessments.

Clinical and imaging characteristics of patients with extreme low back pain or sciatica referred for spinal injection.

PURPOSE: To analyze the causes of pain, imaging characteristics, and therapeutic effect of spinal injection in patients with extreme low back pain or sciatica. METHODS: We analyzed 381 consecutive patients with extreme low back pain or sciatica visiting our spinal intervention center between January and December 2017. Clinical and imaging characteristics were analyzed. The treatment response, defined as a numerical pain rating scale decrease of ≥ 30%, was measured. Fisher's exact test was performed to identify the association between the injection response and subsequent lumbar surgery rate. RESULTS: The most frequent cause of pain was spinal stenosis, followed by herniated intervertebral disc, facet osteoarthritis, and osteoporotic compression fracture. A herniated intervertebral disc was the most common disorder in patients < 50 years of age, while spinal stenosis was the most common in patients ≥ 50 years of age. Women comprised 66.4% of the study population. The majority of lumbar pathologies occurred below L3/4. Spinal injection was found to be effective in 44.2% of cases. Those who responded to the injection showed a significantly lower rate of lumbar surgery within 6 months (P = 0.004). CONCLUSIONS: Those with extreme low back pain or sciatica had clinical and imaging characteristics similar to those with typical low back pain referred for spinal injection. Spinal injection could be an effective method of pain control for patients with extreme low back pain or sciatica.

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

BACKGROUND: The ligamentum teres has been recognized as an important stabilizer of the hip. PURPOSE: We aimed to examine the relationship between non-traumatic ligamentum teres (LT) tear and hip morphometry on magnetic resonance imaging (MRI). MATERIAL AND METHODS: Fifty patients who had undergone hip MRI were included (27 men, 23 women; average age = 54.0 years). The status of the LT and the morphometric hip parameters were assessed, including acetabular anteversion angle (AAA), acetabular depth (AD), acetabular index (AI), lateral center edge angle (LCEA), and extrusion index (EI). The morphometric hip parameters were compared between groups with one-way ANOVA, Student's t-test, and Mann-Whitney U test. RESULTS: A decreased acetabular coverage was noted in the severe tear group compared to the normal group, indicated by a significantly larger AD ( P = 0.001) and smaller LCEA ( P = 0.016). There was a statistically significant difference in the AAA, AD, and LCEA between the normal group and the complete tear group; the AAA was significantly larger ( P = 0.031), the AD was significantly larger ( P = 0.01), and the LCEA was significantly smaller ( P = 0.043) in the complete tear group compared to the normal group. CONCLUSION: There is an association between LT tears and acetabular bony morphology; an insufficient acetabular coverage is associated with complete tear of the LT. As the insufficient acetabular coverage may predispose to ligamentum teres tear, the ligamentum teres should be thoroughly evaluated in those with insufficient acetabular coverage, as a potential cause of hip pain.

The pattern of idiopathic isolated teres minor atrophy with regard to its two-bundle anatomy.

OBJECTIVE: We aimed to analyze the pattern of teres minor atrophy with regard to its two-bundle anatomy and to assess its association with clinical factors. MATERIALS AND METHODS: Shoulder MRIs performed between January and December 2016 were retrospectively reviewed. Images were evaluated for the presence and pattern of isolated teres minor atrophy. Isolated teres minor atrophy was categorized into complete or partial pattern, and partial pattern was further classified according to the portion of the muscle that was predominantly affected. The medical records were reviewed to identify clinical factors associated with teres minor atrophy. RESULTS: Seventy-eight shoulders out of 1,264 (6.2%) showed isolated teres minor atrophy; complete pattern in 41.0%, and partial pattern in 59.0%. Most cases of partial pattern had predominant involvement of the medial-dorsal component (82.6%). There was no significant association between teres minor atrophy and previous trauma, shoulder instability, osteoarthritis, and previous operation. The history of shoulder instability was more frequently found in patients with isolated teres minor atrophy (6.4%), compared with the control group (2.6%), although the difference was not statistically significant. CONCLUSION: Isolated teres minor atrophy may be either complete or partial, and the partial pattern may involve either the medial-dorsal or the lateral-ventral component of the muscle. The imaging findings of partial pattern teres minor atrophy indicate that the two muscle components may have separate innervation.

Epidural steroid injection-related events requiring hospitalisation or emergency room visits among 52,935 procedures performed at a single centre.

OBJECTIVES: To analyse the incidence and type of epidural steroid injection (ESI)-related adverse events, including procedure-related complications and drug-related systemic effects requiring hospitalisation or emergency room (ER) visits. METHODS: This study included 52,935 ESI procedures performed in 22,059 patients in our department from March 2004 to February 2016. Of these, we retrospectively reviewed the cases of 1570 patients (1713 procedures) who were hospitalised or visited the ER within 1 month after ESI. ESI-related events were classified as procedure-related complications, drug-related systemic effects, or of uncertain relationship. Descriptive data are provided; no statistical analysis was performed. RESULTS: There were 244 ESI-related events in 235 patients (males:females = 102:133; mean age: 65.7 years; range: 20-93 years). The incidence of ESI-related events was 0.46% per procedure, including 14 procedure-related complications, 56 drug-related systemic effects, and 174 events of uncertain cause. Of the 52,935 patients, 6 (0.011%) experienced major complications (two spine haematomas and four infections), 1 patient died, and 1 experienced neurological sequelae. CONCLUSIONS: Although major procedure-related complications and drug-related systemic effects of ESI requiring hospitalisation are very rare, infection and haematoma can occur, resulting in serious outcomes. Hence, ESI should be carefully considered in high-risk patients. KEY POINTS: • The incidence of ESI-related events requiring hospitalisation was 0.46%. • The incidence of procedure-related complications was 0.026%. • The incidence of drug-related systemic effects was 0.11%. • The incidence of major complication of ESI was 0.011%. • The major complications were spine infection, haematoma, and sepsis.

Uncovered Medial Meniscus Sign on Knee MRI: Evidence of Lost Brake Stop Mechanism of the Posterior Horn Medial Meniscus.

OBJECTIVE: The objective of our study was to evaluate the association between anterior tibial translation and injuries on the posterior horn medial meniscus (PHMM) and the integrity of the brake stop mechanism of the PHMM in the anterior cruciate ligament (ACL)-deficient knee. MATERIALS AND METHODS: This retrospective study included 85 consecutive patients with an arthroscopically confirmed complete ACL tear. Anterior tibial translation was quantitatively measured using sagittal MRI at the midpoint of the lateral femoral condyle. The "uncovered medial meniscus" sign was considered positive if a vertical line tangent to the posteriormost margin of the medial tibial plateau intersected the PHMM at the midpoint of the medial femoral condyle on sagittal MRI. Concomitant injuries on the structures of the posteromedial and posterolateral corners of the knee, including PHMM tear and meniscal ramp lesion, were recorded. Stratified subgroup analysis and multivariable regression analysis were performed to identify factors associated with anterior tibial translation. RESULTS: The uncovered medial meniscus sign was positive in 21.2% (18/85) of patients and was significantly associated with anterior tibial translation. In the stratified subgroup analysis and multivariable regression analysis, positive uncovered medial meniscus sign consistently showed a significant association with anterior tibial translation and generated an additional 2.8 mm of anterior tibial translation. Other injuries, including PHMM tear and meniscal ramp lesion, were not associated with anterior tibial translation. CONCLUSION: The uncovered medial meniscus sign showed a statistically significant correlation with anterior tibial translation and could be a useful marker for the lost brake stop mechanism of PHMM in the ACL-deficient knee.