[Imaging of the anterior cruciate ligament and anterolateral rotational instability of the knee joint]. / Bildgebung des vorderen Kreuzbands und der anterolateralen Rotationsinstabilität des Kniegelenks.

The anterior cruciate ligament (ACL) is essential for the stability of the knee joint and ACL tears are one of the most common sports injuries with a high incidence, especially in sports that require rotational movements and abrupt changes in direction. Injuries of the ACL are rarely isolated and are often accompanied by meniscal and other internal knee injuries, which increase the risk of osteoarthritis. The spectrum of ACL injuries includes strains, partial tears and complete tears. Magnetic resonance imaging (MRI) plays a pivotal role in the diagnostics as it can accurately depict not only the ACL but also accompanying injuries. Proton density and T2-weighted sequences are particularly suitable for evaluating the ACL, which is usually well visible and assessable in all planes. In addition to depicting fiber disruption as a direct sign and central diagnostic indicator of an ACL tear, there are numerous other direct and indirect signs of an ACL injury in MRI. These include abnormal fiber orientations, signal increases and an anterior subluxation of the tibia relative to the femur. The bone marrow edema patterns often associated with ACL tears are indicative of the underlying injury mechanism. The treatment of ACL tears can be conservative or surgical depending on various factors, such as the patient's activity level and the presence of accompanying injuries. The precise and comprehensive description of ACL injuries by radiology is crucial for optimal treatment planning. Anterolateral rotational instability (ALRI) of the knee joint characterizes a condition of excessive lateral and rotational mobility of the tibia in relation to the femur in the anterolateral knee region. This instability is primarily caused by a rupture of the ACL, with the anterolateral ligament (ALL) that was rediscovered about 10 years ago, also being attributed a role in stabilizing the knee. Although ALRI is primarily diagnosed through clinical examinations, MRI is indispensable for detecting injuries to the ACL, ALL, and other internal knee structures, which is essential for developing an optimal treatment strategy.

AI-Based Measurement of Lumbar Spinal Stenosis on MRI: External Evaluation of a Fully Automated Model.

OBJECTIVES: The aim of this study was to clinically validate a fully automated AI model for magnetic resonance imaging (MRI)-based quantifications of lumbar spinal canal stenosis. MATERIALS AND METHODS: This retrospective study included lumbar spine MRI of 100 consecutive clinical patients (56 ± 17 years; 43 females, 57 males) performed on clinical 1.5 (51 examinations) and 3 T MRI scanners (49 examinations) with heterogeneous clinical imaging protocols. The AI model performed segmentations of the thecal sac on axial T2-weighted sequences. Based on these segmentations, the anteroposterior (AP) and mediolateral (ML) distance, and the area of the thecal sac were measured in a fully automated manner. For comparison, 2 fellowship-trained musculoskeletal radiologists performed the same segmentations and measurements independently. Statistics included 1-sample t tests, the intraclass correlation coefficient (ICC), Bland-Altman plots, and Dice coefficients. A P value of <0.05 was considered statistically significant. RESULTS: The average measurements of the AI model, reader 1, and reader 2 were 194 ± 72 mm2, 181 ± 71 mm2, and 179 ± 70 mm2 for thecal sac area, 13 ± 3.3 mm, 12.6 ± 3.3 mm, and 12.6 ± 3.2 mm for AP distance, and 19.5 ± 3.9 mm, 20 ± 4.3 mm, and 19.4 ± 4 mm for ML distance, respectively. Significant differences existed for all pairwise comparisons, besides reader 1 versus AI model for the ML distance and reader 1 versus reader 2 for the AP distance (P = 0.1 and P = 0.21, respectively). The pairwise mean absolute errors among reader 1, reader 2, and the AI model ranged from 0.59 mm and 0.75 mm for the AP distance, from 1.16 mm to 1.37 mm for the ML distance, and from 7.9 mm2 to 15.54 mm2 for the thecal sac area. Pairwise ICCs among reader 1, reader 2, and the AI model ranged from 0.91 and 0.94 for the AP distance and from 0.86 to 0.9 for the ML distance without significant differences. For the thecal sac area, the pairwise ICC between both readers and the AI model of 0.97 each was slightly, but significantly lower than the ICC between reader 1 and reader 2 of 0.99. Similarly, the Dice coefficient and Hausdorff distance between both readers and the AI model were significantly lower than the values between reader 1 and reader 2, overall ranging from 0.93 to 0.95 for the Dice coefficients and 1.1 to 1.44 for the Hausdorff distances. CONCLUSIONS: The investigated AI model is reliable for assessing the AP and the ML thecal sac diameters with human level accuracies. The small differences for measurement and segmentation of the thecal sac area between the AI model and the radiologists are likely within a clinically acceptable range.

Multiaxial 3D MRI of the Ankle: Advanced High-Resolution Visualization of Ligaments, Tendons, and Articular Cartilage.

MRI is a valuable tool for diagnosing a broad spectrum of acute and chronic ankle disorders, including ligament tears, tendinopathy, and osteochondral lesions. Traditional two-dimensional (2D) MRI provides a high image signal and contrast of anatomic structures for accurately characterizing articular cartilage, bone marrow, synovium, ligaments, tendons, and nerves. However, 2D MRI limitations are thick slices and fixed slice orientations. In clinical practice, 2D MRI is limited to 2 to 3 mm slice thickness, which can cause blurred contours of oblique structures due to volume averaging effects within the image slice. In addition, image plane orientations are fixated and cannot be changed after the scan, resulting in 2D MRI lacking multiplanar and multiaxial reformation abilities for individualized image plane orientations along oblique and curved anatomic structures, such as ankle ligaments and tendons. In contrast, three-dimensional (3D) MRI is a newer, clinically available MRI technique capable of acquiring high-resolution ankle MRI data sets with isotropic voxel size. The inherently high spatial resolution of 3D MRI permits up to five times thinner (0.5 mm) image slices. In addition, 3D MRI can be acquired image voxel with the same edge length in all three space dimensions (isotropism), permitting unrestricted multiplanar and multiaxial image reformation and postprocessing after the MRI scan. Clinical 3D MRI of the ankle with 0.5 to 0.7 mm isotropic voxel size resolves the smallest anatomic ankle structures and abnormalities of ligament and tendon fibers, osteochondral lesions, and nerves. After acquiring the images, operators can align image planes individually along any anatomic structure of interest, such as ligaments and tendons segments. In addition, curved multiplanar image reformations can unfold the entire course of multiaxially curved structures, such as perimalleolar tendons, into one image plane. We recommend adding 3D MRI pulse sequences to traditional 2D MRI protocols to visualize small and curved ankle structures to better advantage. This article provides an overview of the clinical application of 3D MRI of the ankle, compares diagnostic performances of 2D and 3D MRI for diagnosing ankle abnormalities, and illustrates clinical 3D ankle MRI applications.

Fixed Subluxation of the Distal Radioulnar Joint following Malunion of the Ulnar Styloid Process.

Purpose Recent literature on significance and treatment of ulnar styloid fractures suggest that the ulnar styloid is not the central problem but the radioulnar ligaments and their impact on joint stability. However, specifically displaced ulnar styloid process fractures that secondarily heal in an ectopic position remain a rare situation for which diagnostics and treatment options remain a topic of discussion. Methods This case series presents four patients with limited supination due to a fixed dorsal subluxation of the distal radioulnar joint (DRUJ). The reason here fore was a significant malunion of ulnar styloid fracture that was addressed by corrective ulnar styloid osteotomy. Three of these osteotomies used three-dimensional (3D) preoperative planning and patient specific guides. Results All patients presented with a significant displacement of the malunited ulnar styloid fracture (average 32-degree rotation and 5-mm translation). In all four patients, the fixed subluxation of the ulnar head was resolved clinically and radiographically, and the forearm rotation restored after corrective osteotomy of the ulnar styloid and fixation in an anatomical position. Conclusion This case series presents a very specific subset of patients with nonanatomically healed ulnar styloid fractures responsible for a chronic DRUJ dislocation and limited prosupination and its treatment. Level of evidence This is a Level IV, therapeutic study.

MR Imaging-Ultrasonography Correlation of Acute and Chronic Foot and Ankle Conditions.

Foot and ankle injuries are common musculoskeletal disorders. In the acute setting, ligamentous injuries are most common, whereas fractures, osseous avulsion injuries, tendon and retinaculum tears, and osteochondral injuries are less common. The most common chronic and overuse injuries include osteochondral and articular cartilage defects, tendinopathies, stress fractures, impingement syndromes, and neuropathies. Common forefoot conditions include traumatic and stress fractures, metatarsophalangeal and plantar plate injuries and degenerations, intermittent bursitis, and perineural fibrosis. Ultrasonography is well-suited for evaluating superficial tendons, ligaments, and muscles. MR imaging is best for deeper-located soft tissue structures, articular cartilage, and cancellous bone.

2D versus 3D MRI of osteoarthritis in clinical practice and research.

Accurately detecting and characterizing articular cartilage defects is critical in assessing patients with osteoarthritis. While radiography is the first-line imaging modality, magnetic resonance imaging (MRI) is the most accurate for the noninvasive assessment of articular cartilage. Multiple semiquantitative grading systems for cartilage lesions in MRI were developed. The Outerbridge and modified Noyes grading systems are commonly used in clinical practice and for research. Other useful grading systems were developed for research, many of which are joint-specific. Both two-dimensional (2D) and three-dimensional (3D) pulse sequences are used to assess cartilage morphology and biochemical composition. MRI techniques for morphological assessment of articular cartilage can be categorized into 2D and 3D FSE/TSE spin-echo and gradient-recalled echo sequences. T2 mapping is most commonly used to qualitatively assess articular cartilage microstructural composition and integrity, extracellular matrix components, and water content. Quantitative techniques may be able to label articular cartilage alterations before morphological defects are visible. Accurate detection and characterization of shallow low-grade partial and small articular cartilage defects are the most challenging for any technique, but where high spatial resolution 3D MRI techniques perform best. This review article provides a practical overview of commonly used 2D and 3D MRI techniques for articular cartilage assessments in osteoarthritis.

Cerebrospinal Fluid Pressure Dynamics as a Bedside Test in Traumatic Spinal Cord Injury to Assess Surgical Spinal Cord Decompression: Safety, Feasibility, and Proof-of-Concept.

BACKGROUND: Sufficient and timely spinal cord decompression is a critical surgical objective for neurological recovery in spinal cord injury (SCI). Residual cord compression may be associated with disturbed cerebrospinal fluid pressure (CSFP) dynamics. OBJECTIVES: This study aims to assess whether intrathecal CSFP dynamics in SCI following surgical decompression are feasible and safe, and to explore the diagnostic utility. METHODS: Prospective cohort study. Bedside lumbar CSFP dynamics and cervical MRI were obtained following surgical decompression in N = 9 with mostly cervical acute-subacute SCI and N = 2 patients with non-traumatic SCI. CSFP measurements included mean CSFP, cardiac-driven CSFP peak-to-valley amplitudes (CSFPp), Valsalva maneuver, and Queckenstedt's test (firm pressure on jugular veins, QT). From QT, proxies for cerebrospinal fluid pulsatility curve were calculated (ie, relative pulse pressure coefficient; RPPC-Q). CSFP metrics were compared to spine-healthy patients. computer tomography (CT)-myelography was done in 3/8 simultaneous to CSFP measurements. RESULTS: Mean age was 45 ± 9 years (range 17-67; 3F), SCI was complete (AIS A, N = 5) or incomplete (AIS B-D, N = 6). No adverse events related to CSFP assessments. CSFP rise during QT was induced in all patients [range 9.6-26.6 mmHg]. However, CSFPp was reduced in 3/11 (0.1-0.3 mmHg), and in 3/11 RPPC-Q was abnormal (0.01-0.05). Valsalva response was reduced in 8/11 (2.6-23.4 mmHg). CSFP dynamics corresponded to CT-myelography. CONCLUSIONS: Comprehensive bedside lumbar CSFP dynamics in SCI following decompression are safe, feasible, and can reveal distinct patterns of residual spinal cord compression. Longitudinal studies are required to define critical thresholds of impaired CSFP dynamics that may impact neurological recovery and requiring surgical revisions.

MR Imaging of Acute Knee Injuries: Systematic Evaluation and Reporting.

Acute knee injury ranges among the most common joint injuries in professional and recreational athletes. Radiographs can detect joint effusion, fractures, deformities, and malalignment; however, MR imaging is most accurate for radiographically occult fractures, chondral injury, and soft tissue injuries. Using a structured checklist approach for systematic MR imaging evaluation and reporting, this article reviews the MR imaging appearances of the spectrum of traumatic knee injuries, including osteochondral injuries, cruciate ligament tears, meniscus tears and ramp lesions, anterolateral complex and collateral ligament injuries, patellofemoral translation, extensor mechanism tears, and nerve and vascular injuries.

Radiomics and Deep Learning for Disease Detection in Musculoskeletal Radiology: An Overview of Novel MRI- and CT-Based Approaches.

ABSTRACT: Radiomics and machine learning-based methods offer exciting opportunities for improving diagnostic performance and efficiency in musculoskeletal radiology for various tasks, including acute injuries, chronic conditions, spinal abnormalities, and neoplasms. While early radiomics-based methods were often limited to a smaller number of higher-order image feature extractions, applying machine learning-based analytic models, multifactorial correlations, and classifiers now permits big data processing and testing thousands of features to identify relevant markers. A growing number of novel deep learning-based methods describe magnetic resonance imaging- and computed tomography-based algorithms for diagnosing anterior cruciate ligament tears, meniscus tears, articular cartilage defects, rotator cuff tears, fractures, metastatic skeletal disease, and soft tissue tumors. Initial radiomics and deep learning techniques have focused on binary detection tasks, such as determining the presence or absence of a single abnormality and differentiation of benign versus malignant. Newer-generation algorithms aim to include practically relevant multiclass characterization of detected abnormalities, such as typing and malignancy grading of neoplasms. So-called delta-radiomics assess tumor features before and after treatment, with temporal changes of radiomics features serving as surrogate markers for tumor responses to treatment. New approaches also predict treatment success rates, surgical resection completeness, and recurrence risk. Practice-relevant goals for the next generation of algorithms include diagnostic whole-organ and advanced classification capabilities. Important research objectives to fill current knowledge gaps include well-designed research studies to understand how diagnostic performances and suggested efficiency gains of isolated research settings translate into routine daily clinical practice. This article summarizes current radiomics- and machine learning-based magnetic resonance imaging and computed tomography approaches for musculoskeletal disease detection and offers a perspective on future goals and objectives.

Extent of posterolateral tibial plateau impaction fracture correlates with anterolateral complex injury and has an impact on functional outcome after ACL reconstruction.

PURPOSE: The impact of posterolateral tibial plateau impaction fractures (TPIF) on posttraumatic knee stability in the setting of primary anterior cruciate ligament (ACL) tear is unknown. The main objective was to determine whether increased bone loss of the posterolateral tibial plateau is associated with residual rotational instability and impaired functional outcome after ACL reconstruction. METHODS: A cohort was identified in a prospective enrolled study of patients suffering acute ACL injury who underwent preoperative standard radiographic diagnostics and clinical evaluation. Patients were included when scheduled for isolated single-bundle hamstring autograft ACL reconstruction. Exclusion criteria were concurrent anterolateral complex (ALC) reconstruction (anterolateral tenodesis), previous surgery or symptoms in the affected knee, partial ACL tear, multi-ligament injury with an indication for additional surgical intervention, and extensive cartilage wear. On MRI, bony (TPIF, tibial plateau, and femoral condyle morphology) and ligament status (ALC, concomitant collateral ligament, and meniscus injuries) were assessed by a musculoskeletal radiologist. Clinical evaluation consisted of KT-1000, pivot-shift, and Lachman testing, as well as Tegner activity and IKDC scores. RESULTS: Fifty-eight patients were included with a minimum follow-up of 12 months. TPIF was identified in 85% of ACL injuries (n = 49). The ALC was found to be injured in 31 of 58 (53.4%) cases. Pearson analysis showed a positive correlation between TPIF and the degree of concomitant ALC injury (p < 0.001). Multiple regression analysis revealed an increased association of high-grade TPIF with increased lateral tibial convexity (p = 0.010). The high-grade TPIF group showed worse postoperative Tegner scores 12 months postoperatively (p = 0.035). CONCLUSION: Higher degrees of TPIFs are suggestive of a combined ACL/ALC injury. Moreover, patients with increased posterolateral tibial plateau bone loss showed lower Tegner activity scores 12 months after ACL reconstruction. LEVEL OF EVIDENCE: III.

Performance of a deep convolutional neural network for MRI-based vertebral body measurements and insufficiency fracture detection.

OBJECTIVES: The aim is to validate the performance of a deep convolutional neural network (DCNN) for vertebral body measurements and insufficiency fracture detection on lumbar spine MRI. METHODS: This retrospective analysis included 1000 vertebral bodies in 200 patients (age 75.2 ± 9.8 years) who underwent lumbar spine MRI at multiple institutions. 160/200 patients had ≥ one vertebral body insufficiency fracture, 40/200 had no fracture. The performance of the DCNN and that of two fellowship-trained musculoskeletal radiologists in vertebral body measurements (anterior/posterior height, extent of endplate concavity, vertebral angle) and evaluation for insufficiency fractures were compared. Statistics included (a) interobserver reliability metrics using intraclass correlation coefficient (ICC), kappa statistics, and Bland-Altman analysis, and (b) diagnostic performance metrics (sensitivity, specificity, accuracy). A statistically significant difference was accepted if the 95% confidence intervals did not overlap. RESULTS: The inter-reader agreement between radiologists and the DCNN was excellent for vertebral body measurements, with ICC values of > 0.94 for anterior and posterior vertebral height and vertebral angle, and good to excellent for superior and inferior endplate concavity with ICC values of 0.79-0.85. The performance of the DCNN in fracture detection yielded a sensitivity of 0.941 (0.903-0.968), specificity of 0.969 (0.954-0.980), and accuracy of 0.962 (0.948-0.973). The diagnostic performance of the DCNN was independent of the radiological institution (accuracy 0.964 vs. 0.960), type of MRI scanner (accuracy 0.957 vs. 0.964), and magnetic field strength (accuracy 0.966 vs. 0.957). CONCLUSIONS: A DCNN can achieve high diagnostic performance in vertebral body measurements and insufficiency fracture detection on heterogeneous lumbar spine MRI. KEY POINTS: • A DCNN has the potential for high diagnostic performance in measuring vertebral bodies and detecting insufficiency fractures of the lumbar spine.

Virtual Care in Nephrology: An In-Depth Retrospective Analysis of Outcomes Using the Reset Kidney Health Model.

The advent of virtual healthcare has reshaped patient management paradigms across various medical domains. This analysis examines the potential effectiveness of treating chronic kidney disease (CKD) using Reset Kidney Health's virtual, multidisciplinary, and integrated care approach. The pilot study concentrated on evaluating the impact of this care model on the estimated Glomerular Filtration Rate (eGFR) of CKD patients over an eight-month period. The analyses showed that a majority of patients managed with the Reset Kidney Health Model experienced stability or improvements in their kidney function, as measured by eGFR. While this pilot study has several limitations, these early results suggest the potential benefits of digital healthcare innovations in chronic disease management and provide an argument for the broader integration of virtual care strategies in healthcare systems. These initial findings could lay the groundwork for further research into effectively integrating digital healthcare in chronic disease management.

Diagnostic Performance of Advanced Metal Artifact Reduction MRI for Periprosthetic Shoulder Infection.

BACKGROUND: The diagnosis of periprosthetic shoulder infection (PSI) in patients with a painful arthroplasty is challenging. Magnetic resonance imaging (MRI) may be helpful, but shoulder implant-induced metal artifacts degrade conventional MRI. Advanced metal artifact reduction (MARS) improves the visibility of periprosthetic bone and soft tissues. The purpose of our study was to determine the reliability, repeatability, and diagnostic performance of advanced MARS-MRI findings for diagnosing PSI. METHODS: Between January 2015 and December 2019, we enrolled consecutive patients suspected of having PSI at our academic hospital. All 89 participants had at least 1-year clinical follow-up and underwent standardized clinical, radiographic, and laboratory evaluations and advanced MARS-MRI. Two fellowship-trained musculoskeletal radiologists retrospectively evaluated the advanced MARS-MRI studies for findings associated with PSI in a blinded and independent fashion. Both readers repeated their evaluations after a 2-month interval. Interreader reliability and intrareader repeatability were assessed with κ coefficients. The diagnostic performance of advanced MARS-MRI for PSI was quantified using sensitivity, specificity, and the area under the receiver operating characteristic curve (AUC). When applying the International Consensus Meeting (ICM) 2018 criteria, of the 89 participants, 22 (25%) were deemed as being infected and 67 (75%) were classified as being not infected (unlikely to have PSA and not requiring a surgical procedure during 1-year follow-up). RESULTS: The interreader reliability and intrareader repeatability of advanced MARS-MRI findings, including lymphadenopathy, joint effusion, synovitis, extra-articular fluid collection, a sinus tract, rotator cuff muscle edema, and periprosthetic bone resorption, were good (κ = 0.61 to 0.80) to excellent (κ > 0.80). Lymphadenopathy, complex joint effusion, and edematous synovitis had sensitivities of >85%, specificities of >90%, odds ratios of >3.6, and AUC values of >0.90 for diagnosing PSI. The presence of all 3 findings together yielded a PSI probability of >99%, per logistic regression analysis. CONCLUSIONS: Our study shows the clinical utility of advanced MARS-MRI for diagnosing PSI when using the ICM 2018 criteria as the reference standard. Although the reliability and diagnostic accuracy were high, these conclusions are based on our specific advanced MARS-MRI protocol interpreted by experienced musculoskeletal radiologists. Investigations with larger sample sizes are needed to confirm these results. LEVEL OF EVIDENCE: Diagnostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Bone marrow edema of the medioplantar talar head is associated with severe ligamentous injury in ankle sprain.

PURPOSE: To investigate the predictive value of talar head edema (THE) in acute ankle sprain for the presence of concomitant ligament injuries. METHODS: This retrospective study was approved by the ethics committee and informed consent was obtained. One hundred patients (mean age: 37 years ± 14 [standard deviation], range 13-77 years) with MRI of the ankle after acute trauma were included. The cohort in this matched-pair study consisted of 50 patients with THE (group 1) and 50 patients without THE (group 2). Two readers independently evaluated presence and size of bone marrow edema of the talus head and injuries of the lateral, medial, talonavicular, and spring ligament complex. Statistics included intraclass correlation coefficient (ICC) and Kappa statistics as well as parametric and non-parametric tests. RESULTS: On average, patients with THE demonstrated significantly more ligament injuries in comparison to patients without THE (3.7 vs. 1.3, p ≤ 0.01). Also, in patients with THE, the number of injured ligaments was significantly higher at the lateral (p = 0.03), medial (p ≤ 0.01), and talonavicular (p ≤ 0.01) compartment in comparison to patients without THE. The most frequently injured ligaments in patients with THE were the anterior talofibular ligament (60%) and the anterior tibiotalar ligament (42%). There was no significant correlation between edema size and the number of injured ligaments or compartments (p = 0.5). CONCLUSION: THE is associated with more extensive ligamentous ankle injury, in particular to the medial and lateral collateral ligament complex, and therefore indicative of severe ankle trauma.

Tibial internal rotation in combined anterior cruciate ligament and high-grade anterolateral ligament injury and its influence on ACL length.

BACKGROUND: Assessment of combined anterolateral ligament (ALL) and anterior cruciate ligament (ACL) injury remains challenging but of high importance as the ALL is a contributing stabilizer of tibial internal rotation. The effect of preoperative static tibial internal rotation on ACL -length remains unknown. The aim of the study was analyze the effect of tibial internal rotation on ACL length in single-bundle ACL reconstructions and to quantify tibial internal rotation in combined ACL and ALL injuries. METHODS: The effect of tibial internal rotation on ACL length was computed in a three-dimensional (3D) model of 10 healthy knees with 5° increments of tibial internal rotation from 0 to 30° resulting in 70 simulations. For each step ACL length was measured. ALL injury severity was graded by a blinded musculoskeletal radiologist in a retrospective analysis of 61 patients who underwent single-bundle ACL reconstruction. Preoperative tibial internal rotation was measured in magnetic resonance imaging (MRI) and its diagnostic performance was analyzed. RESULTS: ACL length linearly increased 0.7 ± 0.1 mm (2.1 ± 0.5% of initial length) per 5° of tibial internal rotation from 0 to 30° in each patient. Seventeen patients (27.9%) had an intact ALL (grade 0), 10 (16.4%) a grade 1, 21 (34.4%) a grade 2 and 13 (21.3%) a grade 3 injury of the ALL. Patients with a combined ACL and ALL injury grade 3 had a median static tibial internal rotation of 8.8° (interquartile range (IQR): 8.3) compared to 5.6° (IQR: 6.6) in patients with an ALL injury (grade 0-2) (p = 0.03). A cut-off > 13.3° of tibial internal rotation predicted a high-grade ALL injury with a specificity of 92%, a sensitivity of 30%; area under the curve (AUC) 0.70 (95% CI: 0.54-0.85) (p = 0.03) and an accuracy of 79%. CONCLUSION: ACL length linearly increases with tibial internal rotation from 0 to 30°. A combined ACL and high-grade ALL injury was associated with greater preoperative tibial internal rotation. This potentially contributes to unintentional graft laxity in ACL reconstructed patients, in particular with concomitant high-grade ALL tears. STUDY DESIGN: Cohort study; Level of evidence, 3.

MRI findings of ischiofemoral impingement after total hip arthroplasty are associated with increased femoral antetorsion.

BACKGROUND: Ischiofemoral impingement (IFI) is a known complication after total hip arthroplasty (THA). PURPOSE: To assess if increased postoperative (FA) is associated with magnetic resonance imaging (MRI) findings of IFI. MATERIAL AND METHODS: In 221 patients with THA, two independent readers measured FA, ischiofemoral space (IFS), quadratus femoris space (QFS), edema, and fatty infiltration of quadratus femoris muscle. Three sets of IFI-imaging features were defined: acute IFI (set 1): IFS ≤15 mm or QFS ≤10 mm and edema in the quadratus femoris muscle; chronic IFI (set 2): IFS ≤15 mm or QFS ≤10 mm and fatty infiltration of quadratus femoris muscle Goutallier grade ≥2; acute and chronic IFI (set 3) with both criteria applicable. For each set, FA angles were compared between positive findings of IFI and negative findings of IFI. The t-test for independent samples tested statistical significance. RESULTS: In 7.2% (16/221) of patients, findings of IFI (IFS ≤15 mm or QFS ≤10 mm and edema, n = 1; fatty infiltration, n = 9; or both, n = 6) were observed. In women, 11.4% (14/123) exhibited findings of IFI compared to 2.0% (2/98) in men. Comparison in set 1 (n = 7): mean antetorsion of 23.9° ± 9.8° (findings of acute IFI) compared to 14.4° ± 9.7° (P = 0.01). Comparison in set 2 (n = 15): mean antetorsion of 16.2° ± 6.3° (findings of chronic IFI) compared to 14.5° ± 9.9° (P = 0.49). Comparison in set 3 (n = 6): mean antetorsion of 20.4° ± 3.8° (findings of acute and chronic IFI) compared to 14.5° ± 9.9° (P = 0.01). CONCLUSION: After THA, high postoperative FA is associated with MRI findings of acute as well as acute and chronic IFI. Findings of IFI were commonly seen in women.

Outcomes of Tibialis Anterior Tendon Reconstruction with Autograft or Allograft.

BACKGROUND: In cases of tibialis anterior tendon (TAT) ruptures associated with significant tendon defect, an interposition graft is often needed for reconstruction. Both auto- and allograft reconstructions have been described in the literature. Our hypothesis was that both graft types would have a good integrity and provide comparable outcomes. METHODS: Patients who underwent TAT reconstruction using either an auto- or allograft were identified. Patient-reported outcomes (PROs) were collected using the 12-Item Short Form Health Survey (SF-12) questionnaire, the American Orthopaedic Foot & Ankle Society (AOFAS) hindfoot score, the Foot Function Index (FFI), and the Karlsson-Peterson score. Functional outcome was assessed by isokinetic strength measurement. Outcomes were further assessed with magnetic resonance imaging (MRI) evaluation of graft integrity. All measurements were also performed for the contralateral foot. RESULTS: Twenty-one patients with an average follow-up of 82 months (20-262 months), comprising 12 allograft and 9 autograft TAT reconstructions, were recruited. There were no significant differences in patient-reported outcomes between allograft reconstructions and autografts: SF-12 (30.7 vs 31.1, P = .77); AOFAS (83 vs 91.2, P = .19); FFI (20.7% vs 9.5%, P = .22); and Karlsson-Peterson (78.9 vs 87.1, P = .23). All grafts (100%) were intact on MRI with a well-preserved integrity and no signs of new rupture. There were no major differences in range of motion and functional outcomes as measured by strength testing between the operative and nonoperative side. CONCLUSION: Reconstructions of TAT achieved good PROs, as well as functional and imaging results with a preserved graft integrity in all cases. There were no substantial differences between allograft and autograft reconstructions. LEVEL OF EVIDENCE: Level IV, retrospective case series.

CT-guided transforaminal epidural steroid injection for discogenic lumbar radiculopathy: influence of contrast dispersion and radiologist's experience on clinical outcome.

OBJECTIVE: To investigate the impact of contrast dispersion pattern/location during lumbar CT-guided transforaminal epidural steroid injection (TFESI) and experience of the performing radiologist on therapeutic outcome. MATERIALS AND METHODS: In this single-center retrospective cohort study, two observers analyzed contrast dispersion during CT-guided TFESI of 204 patients (age 61.1 ± 14 years) with discogenic unilateral single-level L4 or L5 radiculopathy. The contrast dispersion pattern was classified as "focal," "linear," or "tram-track"; the location was divided into "extraforaminal," "foraminal," or "recessal." Pain was assessed before and 4 weeks after treatment using a numerical rating scale (0, no pain; 10, intolerable pain). Additionally, the patient global impression of change (PGIC) was assessed. The TFESI was performed by musculoskeletal radiologists (experience range: first year of musculoskeletal fellowship training to 19 years). Contrast pattern/location and radiologist's experience were compared between "good responder" (≥ 50% pain reduction) and "poor responder" (< 50%). A p-value < 0.05 was considered to be statistically significant. RESULTS: Overall, CT-guided TFESI resulted in a substantial pain reduction in 46.6% of patients with discogenic radiculopathy. The contrast dispersion pattern and location had no effect on pain relief (p = 0.75 and p = 0.09) and PGIC (p = 0.70 and p = 0.21) 4 weeks after TFESI. Additionally, the experience of the radiologist had no influence on pain reduction (p = 0.92) or PGIC (p = 0.75). Regarding pre-interventional imaging findings, both the location and grading of nerve compression had no effect on pain relief (p = 0.91 and p = 0.85) and PGIC (p = 0.18 and p = 0.31). CONCLUSION: Our results indicate that neither contrast agent dispersion/location nor the experience of the radiologist allows predicting the therapeutic outcome 4 weeks after the procedure.

Artificial intelligence for MRI diagnosis of joints: a scoping review of the current state-of-the-art of deep learning-based approaches.

Deep learning-based MRI diagnosis of internal joint derangement is an emerging field of artificial intelligence, which offers many exciting possibilities for musculoskeletal radiology. A variety of investigational deep learning algorithms have been developed to detect anterior cruciate ligament tears, meniscus tears, and rotator cuff disorders. Additional deep learning-based MRI algorithms have been investigated to detect Achilles tendon tears, recurrence prediction of musculoskeletal neoplasms, and complex segmentation of nerves, bones, and muscles. Proof-of-concept studies suggest that deep learning algorithms may achieve similar diagnostic performances when compared to human readers in meta-analyses; however, musculoskeletal radiologists outperformed most deep learning algorithms in studies including a direct comparison. Earlier investigations and developments of deep learning algorithms focused on the binary classification of the presence or absence of an abnormality, whereas more advanced deep learning algorithms start to include features for characterization and severity grading. While many studies have focused on comparing deep learning algorithms against human readers, there is a paucity of data on the performance differences of radiologists interpreting musculoskeletal MRI studies without and with artificial intelligence support. Similarly, studies demonstrating the generalizability and clinical applicability of deep learning algorithms using realistic clinical settings with workflow-integrated deep learning algorithms are sparse. Contingent upon future studies showing the clinical utility of deep learning algorithms, artificial intelligence may eventually translate into clinical practice to assist detection and characterization of various conditions on musculoskeletal MRI exams.

External snapping hip syndrome is associated with an increased femoral offset.

BACKGROUND: External snapping hip syndrome (ESH) is postulated to be one of the causes of greater trochanteric pain syndrome, which also includes greater trochanteric bursitis and tendinopathy or tears of the hip abductor mechanism. However, it was not yet described what kind of bony morphology can cause the snapping and whether symptomatic and asymptomatic individuals have different imaging features. PURPOSE: It was the purpose of this study to look for predisposing morphological factors for ESH and to differentiate between painful and asymptomatic snapping. METHODS: A consecutive cohort with ESH and available magnetic resonance imaging (MRI) between 2014 and 2019 was identified. The control group consisted of patients that underwent corrective osteotomies around the knee for mechanical axis correction and never complained of hip symptoms nor had undergone previous hip procedures. The following parameters were blindly assessed for determination of risk factors for ESH: CCD (corpus collum diaphysis) angle; femoral and global offset; femoral antetorsion; functional femoral antetorsion; translation of the greater trochanter (GT); posterior tilt of the GT; pelvic width/anterior pelvic length; intertrochanteric width. Hip and pelvic offset indexes were calculated as ratios of femoral/global offset and intertrochanteric/pelvic width, respectively. For the comparison of symptomatic and asymptomatic snapping, the following soft-tissue signs were investigated: presence of trochanteric bursitis or gluteal tendinopathy; presence of surface bony irregularities on trochanter major and ITB (Iliotibial band) thickness. RESULTS: A total of 31 hips with ESH were identified. The control group (n = 29) consisted of patients matched on both age (± 1) and gender. Multiple regression analysis determined an increased hip offset index to be independent predictor of ESH (r = + 0.283, p = 0.025), most likely due to the higher femoral offset in the ESH group (p = 0.031). Pearson correlation analysis could not identify any significant secondary factors. No differences were found between painful and asymptomatic snapping on MRI. CONCLUSIONS: A high hip offset index was found as an independent predictor for external snapping hip in our cohort, mainly due to increased femoral offset. No imaging soft-tissue related differences could be outlined between symptomatic and asymptomatic external snapping. LEVEL OF EVIDENCE III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors   www.springer.com/00590 .