Hip joint contact pressure and force: a scoping review of in vivo and cadaver studies.

Aims: Research on hip biomechanics has analyzed femoroacetabular contact pressures and forces in distinct hip conditions, with different procedures, and used diverse loading and testing conditions. The aim of this scoping review was to identify and summarize the available evidence in the literature for hip contact pressures and force in cadaver and in vivo studies, and how joint loading, labral status, and femoral and acetabular morphology can affect these biomechanical parameters. Methods: We used the PRISMA extension for scoping reviews for this literature search in three databases. After screening, 16 studies were included for the final analysis. Results: The studies assessed different hip conditions like labrum status, the biomechanical effect of the cam, femoral version, acetabular coverage, and the effect of rim trimming. The testing and loading conditions were also quite diverse, and this disparity limits direct comparisons between the different researches. With normal anatomy the mean contact pressures ranged from 1.54 to 4.4 MPa, and the average peak contact pressures ranged from 2 to 9.3 MPa. Labral tear or resection showed an increase in contact pressures that diminished after repair or reconstruction of the labrum. Complete cam resection also decreased the contact pressure, and acetabular rim resection of 6 mm increased the contact pressure at the acetabular base. Conclusion: To date there is no standardized methodology to access hip contact biomechanics in hip arthroscopy, or with the preservation of the periarticular soft-tissues. A tendency towards improved biomechanics (lower contact pressures) was seen with labral repair and reconstruction techniques as well as with cam correction.

Interdisciplinary consensus statements on imaging of DRUJ instability and TFCC injuries.

OBJECTIVES: The purpose of this agreement was to establish evidence-based consensus statements on imaging of distal radioulnar joint (DRUJ) instability and triangular fibrocartilage complex (TFCC) injuries by an expert group using the Delphi technique. METHODS: Nineteen hand surgeons developed a preliminary list of questions on DRUJ instability and TFCC injuries. Radiologists created statements based on the literature and the authors' clinical experience. Questions and statements were revised during three iterative Delphi rounds. Delphi panelists consisted of twenty-seven musculoskeletal radiologists. The panelists scored their degree of agreement to each statement on an 11-item numeric scale. Scores of "0," "5," and "10" reflected complete disagreement, indeterminate agreement, and complete agreement, respectively. Group consensus was defined as a score of "8" or higher for 80% or more of the panelists. RESULTS: Three of fourteen statements achieved group consensus in the first Delphi round and ten statements achieved group consensus in the second Delphi round. The third and final Delphi round was limited to the one question that did not achieve group consensus in the previous rounds. CONCLUSIONS: Delphi-based agreements suggest that CT with static axial slices in neutral rotation, pronation, and supination is the most useful and accurate imaging technique for the work-up of DRUJ instability. MRI is the most valuable technique in the diagnosis of TFCC lesions. The main indication for MR arthrography and CT arthrography are Palmer 1B foveal lesions of the TFCC. CLINICAL RELEVANCE STATEMENT: MRI is the method of choice for assessing TFCC lesions, with higher accuracy for central than peripheral abnormalities. The main indication for MR arthrography is the evaluation of TFCC foveal insertion lesions and peripheral non-Palmer injuries. KEY POINTS: • Conventional radiography should be the initial imaging technique in the assessment of DRUJ instability. CT with static axial slices in neutral rotation, pronation, and supination is the most accurate method for evaluating DRUJ instability. • MRI is the most useful technique in diagnosing soft-tissue injuries causing DRUJ instability, especially TFCC lesions. • The main indications for MR arthrography and CT arthrography are foveal lesions of the TFCC.

Transforaminal Endoscopic Approach to L5S1: Imaging Characterization of the Lower Lumbar Spine and Pelvis for Surgical Planning.

OBJECTIVE: To determine and compare pelvic and lumbosacral reference parameters with computed tomography in patients with low back pain (LBP) and a control group of asymptomatic patients to provide quantification data and morphological correlations for L5S1 transforaminal endoscopic approach (L5S1TEA). METHODS: We prospectively evaluated 100 patients with LBP and a control group of 100 individuals, with spinopelvic computed tomography. We measured lumbopelvic and L5S1 transforaminal approach parameters: maximum approach angle (maxAA) and minimum approach angle (minAA) and skin incision (maxSI and minSI), iliac crest (IC) projection at intersection point (ICPi), distance between the projected intersection of maxAA with the ilium (ICi) and the posterior limit of the IC (ΔICi-ICpost), and distance between ICi and spinous process (ΔICi-SP). RESULTS: Females and ICPi were increased in the LBP group: maxAA: 48.38° ± 5.09°; minAA:32.5° ± 3.90°; maxSI: 11.39 ± 1.86 cm; and minSI: 8.30 ± 1.48 cm. Ilium intersection was increased in males; IC projection at the highest point (ICPh) was higher than ICPi; maxAA intersected the ilium in 28% and minAA in 1.5% of cases; ICi was positively correlated with facet angle, ICPh, and ICPi and negatively with ΔICi-SP. CONCLUSIONS: Our results set preliminary reference values for L5S1TEA surgical planning. Besides higher ICPi, there were no differences between groups in measured parameters. Traditional IC height (ICPh) does not correspond to the point of intersection of the approach and is significantly higher than ICPi. ICi correlated to higher facet angle values, ICPh and ICPi grades, and lower ΔICi-SP. Potential conflict with the ilium is increased in the male population. IC is not impeditive of L5S1TEA in most cases.

Adding false-profile radiographs improves detection of developmental dysplasia of the hip, data from the CHECK cohort.

The aim of this study was to determine the additional value of the false-profile (FP) view radiograph in the diagnosis of developmental dysplasia of the hip (DDH), as compared with an anteroposterior (AP) pelvic radiograph only, and evaluate the correlation between the Wiberg-lateral center edge angle (W-LCEA) and Wiberg-anterior center edge angle (W-ACEA). We used baseline data from a nationwide prospective cohort study (Cohort Hip and Cohort Knee). DDH was quantified on AP pelvic and FP hip radiographs using semi-automatic measurements of the W-LCEA and W-ACEA. A threshold of <20° was used to determine DDH for both the W-LCEA and the W-ACEA. The proportion of DDH only present on the FP view determined the FP view additional value. The correlation between the W-LCEA and W-ACEA was determined. In total 720 participants (1391 hips) were included. DDH was present in 74 hips (5.3%), of which 32 were only present on the FP view radiograph (43.2%). The Pearson correlation coefficient between W-LCEA and W-ACEA of all included hips was 0.547 (95% confidence interval: 0.503-0.591) and 0.441 (95% confidence interval: 0.231-0.652) in hips with DDH. A mean difference of 9.4° (SD 8.09) was present between the W-LCEA and the W-ACEA in the hips with DDH. There is a strong additional value of the FP radiograph in the diagnosis of DDH. Over 4 out of 10 (43.2%) individuals' DDH will be missed when only using the AP radiograph. In hips with DDH a moderate correlation between W-LCEA and W-ACEA was calculated indicating that joints with normal acetabular coverage on the AP view can still be undercovered on the FP view.

Magnetic Resonance Imaging Versus Computed Tomography for Three-Dimensional Bone Imaging of Musculoskeletal Pathologies: A Review.

Magnetic resonance imaging (MRI) is increasingly utilized as a radiation-free alternative to computed tomography (CT) for the diagnosis and treatment planning of musculoskeletal pathologies. MR imaging of hard tissues such as cortical bone remains challenging due to their low proton density and short transverse relaxation times, rendering bone tissues as nonspecific low signal structures on MR images obtained from most sequences. Developments in MR image acquisition and post-processing have opened the path for enhanced MR-based bone visualization aiming to provide a CT-like contrast and, as such, ease clinical interpretation. The purpose of this review is to provide an overview of studies comparing MR and CT imaging for diagnostic and treatment planning purposes in orthopedic care, with a special focus on selective bone visualization, bone segmentation, and three-dimensional (3D) modeling. This review discusses conventional gradient-echo derived techniques as well as dedicated short echo time acquisition techniques and post-processing techniques, including the generation of synthetic CT, in the context of 3D and specific bone visualization. Based on the reviewed literature, it may be concluded that the recent developments in MRI-based bone visualization are promising. MRI alone provides valuable information on both bone and soft tissues for a broad range of applications including diagnostics, 3D modeling, and treatment planning in multiple anatomical regions, including the skull, spine, shoulder, pelvis, and long bones. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY: Stage 3.

Clinical indications for image-guided interventional procedures in the musculoskeletal system: a Delphi-based consensus paper from the European Society of Musculoskeletal Radiology (ESSR)-part VII, nerves of the lower limb.

OBJECTIVES: To perform a Delphi-based consensus on published evidence on image-guided interventional procedures for peripheral nerves of the lower limb (excluding Morton's neuroma) and provide clinical indications. METHODS: We report the results of a Delphi-based consensus of 53 experts from the European Society of Musculoskeletal Radiology who reviewed the published literature for evidence on image-guided interventional procedures offered around peripheral nerves in the lower limb (excluding Morton's neuroma) to derive their clinical indications. Experts drafted a list of statements and graded them according to the Oxford Centre for evidence-based medicine levels of evidence. Consensus was considered strong when > 95% of experts agreed with the statement or broad when > 80% but < 95% agreed. The results of the Delphi-based consensus were used to write the paper. RESULTS: Nine statements on image-guided interventional procedures for peripheral nerves of the lower limb have been drafted. All of them received strong consensus. Image-guided pudendal nerve block is safe, effective, and well tolerated with few complications. US-guided perisciatic injection of anesthetic provides good symptom relief in patients with piriformis syndrome; however, the addition of corticosteroids to local anesthetics still has an unclear role. US-guided lateral femoral cutaneous nerve block can be used to provide effective post-operative regional analgesia. CONCLUSION: Despite the promising results reported by published papers on image-guided interventional procedures for peripheral nerves of the lower limb, there is still a lack of evidence on the efficacy of most procedures. KEY POINTS: • Image-guided pudendal nerve block is safe, effective, and well tolerated with few complications. • US-guided perisciatic injection of anesthetic provides good symptom relief in patients with piriformis syndrome; however, the addition of corticosteroids to local anesthetics still has an unclear role. • US-guided lateral femoral cutaneous nerve block can be used to provide effective post-operative regional analgesia. The volume of local anesthetic affects the size of the blocked sensory area.

Clinical indications for image-guided interventional procedures in the musculoskeletal system: a Delphi-based consensus paper from the European Society of Musculoskeletal Radiology (ESSR)-part VI, foot and ankle.

OBJECTIVES: Clarity regarding accuracy and effectiveness for interventional procedures around the foot and ankle is lacking. Consequently, a board of 53 members of the Ultrasound and Interventional Subcommittees of the European Society of Musculoskeletal Radiology (ESSR) reviewed the published literature to evaluate the evidence on image-guided musculoskeletal interventional procedures around this anatomical region. METHODS: We report the results of a Delphi-based consensus of 53 experts from the European Society of Musculoskeletal Radiology who reviewed the published literature for evidence on image-guided interventional procedures offered around foot and ankle in order to derive their clinical indications. Experts drafted a list of statements and graded them according to the Oxford Centre for evidence-based medicine levels of evidence. Consensus was considered strong when > 95% of experts agreed with the statement or broad when > 80% but < 95% agreed. The results of the Delphi-based consensus were used to write the paper that was shared with all panel members for final approval. RESULTS: A list of 16 evidence-based statements on clinical indications for image-guided musculoskeletal interventional procedures in the foot and ankle were drafted after a literature review. The highest level of evidence was reported for four statements, all receiving 100% agreement. CONCLUSION: According to this consensus, image-guided interventions should not be considered a first-level approach for treating Achilles tendinopathy, while ultrasonography guidance is strongly recommended to improve the efficacy of interventional procedures for plantar fasciitis and Morton's neuroma, particularly using platelet-rich plasma and corticosteroids, respectively. KEY POINTS: • The expert panel of the ESSR listed 16 evidence-based statements on clinical indications of image-guided musculoskeletal interventional procedures in the foot and ankle. • Strong consensus was obtained for all statements. • The highest level of evidence was reached by four statements concerning the effectiveness of US-guided injections of corticosteroid for Morton's neuroma and PRP for plantar fasciitis.

Clinical indications for image-guided interventional procedures in the musculoskeletal system: a Delphi-based consensus paper from the European Society of Musculoskeletal Radiology (ESSR)-part V, knee.

OBJECTIVES: Interventional procedures around the knee are widely adopted for treating different musculoskeletal conditions. A panel of experts from the Ultrasound and Interventional Subcommittees of the European Society of Musculoskeletal Radiology (ESSR) reviewed the existing literature to assess the evidence on image-guided musculoskeletal interventional procedures around the knee, with the goal of highlighting some controversies associated with these procedures, specifically the role of imaging guidance, as well as the efficacy of the medications routinely injected. METHODS: We report the results of a Delphi-based consensus of 53 experts in musculoskeletal radiology, who reviewed the published literature for evidence on image-guided interventional procedures around the knee to derive a list of pertinent clinical indications. RESULTS: A list of 10 statements about clinical indications of image-guided procedures around the knee was created by a Delphi-based consensus. Only two of them had the highest level of evidence; all of them received 100% consensus. CONCLUSIONS: Ultrasonography guidance is strongly recommended for intra-articular and patellar tendinopathy procedures to ensure the precision and efficacy of these treatments. Prospective randomized studies remain warranted to better understand the role of imaging guidance and assess some of the medications used for interventional procedures around the knee. KEY POINTS: • A list of 10 evidence-based statements on clinical indications of image-guided interventional procedures around the knee was produced by an expert panel of the ESSR. • Strong consensus with 100% agreement was obtained for all statements. • Two statements reached the highest level of evidence, allowing us to strongly recommend the use of ultrasonography to guide intra-articular and patellar tendon procedures to ensure higher accuracy and efficacy of these treatments.

Clinical indications for image-guided interventional procedures in the musculoskeletal system: a Delphi-based consensus paper from the European Society of Musculoskeletal Radiology (ESSR)-part IV, hip.

OBJECTIVES: Image-guided musculoskeletal interventional procedures around the hip are widely used in daily clinical practice. The need for clarity concerning the actual added value of imaging guidance and types of medications to be offered led the Ultrasound and the Interventional Subcommittees of the European Society of Musculoskeletal Radiology (ESSR) to promote, with the support of its Research Committee, a collaborative project to review the published literature on image-guided musculoskeletal interventional procedures in the lower limb in order to derive a list of clinical indications. METHODS: In this article, we report the results of a Delphi-based consensus of 53 experts who reviewed the published literature for evidence on image-guided interventional procedures offered in the joint and soft tissues around the hip in order of their clinical indications. RESULTS: Ten statements concerning image-guided treatment procedures around the hip have been collected by the panel of ESSR experts. CONCLUSIONS: This work highlighted that there is still low evidence in the existing literature on some of these interventional procedures. Further large prospective randomized trials are essential to better confirm the benefits and objectively clarify the role of imaging to guide musculoskeletal interventional procedures around the hip. KEY POINTS: • Expert consensus produced a list of 10 evidence-based statements on clinical indications of image-guided interventional procedures around the hip. • The highest level of evidence was only reached for one statement. • Strong consensus was obtained for all statements.

EULAR points to consider for the use of imaging to guide interventional procedures in patients with rheumatic and musculoskeletal diseases (RMDs).

OBJECTIVES: To develop evidence-based Points to Consider (PtC) for the use of imaging modalities to guide interventional procedures in patients with rheumatic and musculoskeletal diseases (RMDs). METHODS: European Alliance of Associations for Rheumatology (EULAR) standardised operating procedures were followed. A systematic literature review was conducted to retrieve data on the role of imaging modalities including ultrasound (US), fluoroscopy, MRI, CT and fusion imaging to guide interventional procedures. Based on evidence and expert opinion, the task force (25 participants consisting of physicians, healthcare professionals and patients from 11 countries) developed PtC, with consensus obtained through voting. The final level of agreement was provided anonymously. RESULTS: A total of three overarching principles and six specific PtC were formulated. The task force recommends preference of imaging over palpation to guide targeted interventional procedures at peripheral joints, periarticular musculoskeletal structures, nerves and the spine. While US is the favoured imaging technique for peripheral joints and nerves, the choice of the imaging method for the spine and sacroiliac joints has to be individualised according to the target, procedure, expertise, availability and radiation exposure. All imaging guided interventions should be performed by a trained specialist using appropriate operational procedures, settings and assistance by technical personnel. CONCLUSION: These are the first EULAR PtC to provide guidance on the role of imaging to guide interventional procedures in patients with RMDs.

Oxford consensus on primary cam morphology and femoroacetabular impingement syndrome: part 1-definitions, terminology, taxonomy and imaging outcomes.

INTRODUCTION: Primary cam morphology is a mostly benign bony prominence that develops at the femoral head-neck junction of the hip, but it is highly prevalent in many athlete populations. In the small proportion of athletes for whom it is not benign, the resulting hip osteoarthritis can be debilitating. Clinicians, athletes, patients and researchers do not yet agree on important primary cam morphology elements. We aimed to ascertain and improve the level of agreement on primary cam morphology definitions, terminology, taxonomy and imaging outcome measures. METHODS: To collect and aggregate informed opinions, an expert panel-the Young Athlete's Hip Research Collaborative-rated primary cam morphology definition, terminology, taxonomy and imaging outcome statements through an online Delphi exercise followed by an online meeting to explore areas of tension and dissent. Reporting followed Conducting and REporting DElphi Studies. RESULTS: A diverse and inclusive Delphi panel (n=65 for rounds 1 and 2, representing 18 countries; 6 stakeholder groups; 40% women) agreed on 35 of 47 statements in 4 domains, while surfacing areas of tension and dissent. This Delphi panel agreed on four key issues essential to moving research and clinical care forward around primary cam morphology. They agreed on: (1) definition, confirming its conceptual attributes (tissue type, size, location, shape and ownership); (2) terminology-use 'morphology' and not terms with a negative connotation like 'lesion', 'abnormality' or 'deformity'; (3) taxonomy, distinguishing between primary and secondary cam morphology, and (4) imaging outcomes, a continuous bone/cartilage alpha angle on radial femoral head-neck MRI for primary cam morphology aetiology research. CONCLUSION: This consensus provides athletes, patients, clinicians and researchers with a strong foundation to guide more precise communication, better clinical decision-making and higher value research about primary cam morphology and its natural history.

Oxford consensus on primary cam morphology and femoroacetabular impingement syndrome: part 2-research priorities on conditions affecting the young person's hip.

INTRODUCTION: Primary cam morphology is highly prevalent in many athlete populations, causing debilitating hip osteoarthritis in some. Existing research is mired in confusion partly because stakeholders have not agreed on key primary cam morphology elements or a prioritised research agenda. We aimed to inform a more rigorous, inclusive and evidence-based approach to research on primary cam morphology and its natural history by working towards agreement on a set of research priorities for conditions affecting the young person's hip. METHODS: An international expert panel-the Young Athlete's Hip Research (YAHiR) Collaborative-rated research priority statements through an online two-round Delphi exercise and met online to explore areas of tension and dissent. Panellists ranked the prioritised research statements according to the Essential National Health Research (ENHR) ranking strategy. Reporting of results followed REPRISE (REporting guideline for PRIority SEtting of health). RESULTS: A diverse Delphi panel (n=65, Delphi rounds 1 and 2; three ENHR strategy surveys: n=49; n=44; n=42) from 18 countries representing six stakeholder groups, prioritised and ranked 18 of 38 research priority statements. The prioritised statements outlined seven research domains: (1) best practice physiotherapy, (2) rehabilitation progression and return to sport, (3) exercise intervention and load management, (4) primary cam morphology prognosis and aetiology, (5) femoroacetabular impingement syndrome prognosis and aetiology, (6) diagnostic criteria, and (7) screening. The panel recommended areas of tension and dissent for the research community to focus on immediately. CONCLUSION: While informing more rigorous, inclusive and evidence-based research, this consensus is a roadmap for researchers, policy-makers and funders to implement research dedicated to reducing the cost and burden of hip disease related to primary cam morphology.

The role of muscle in the susceptibility and progression of axial Spondyloarthritis: The MyoSpA Study Protocol.

BACKGROUND: Axial Spondyloarthritis (axSpA) is a chronic, inflammatory rheumatic disease that affects the axial skeleton, causing pain, stiffness, and fatigue. Genetics and environmental factors such as microbiota and microtrauma are known causes of disease susceptibility and progression. Murine models of axSpA found a decisive role for biomechanical stress as an inducer of enthesitis and new bone formation. Here, we hypothesize that muscle properties in axSpA patients are compromised and influenced by genetic background. OBJECTIVES: To improve our current knowledge of axSpA physiopathology, we aim to characterize axial and peripheral muscle properties and identify genetic and protein biomarker that might explain such properties. METHODS: A cross-sectional study will be conducted on 48 participants aged 18-50 years old, involving patients with axSpA (according to ASAS classification criteria, symptoms duration < 10 years) and healthy controls matched by gender, age, and levels of physical activity. We will collect epidemiological and clinical data and perform a detailed, whole body and segmental, myofascial characterization (focusing on multifidus, brachioradialis and the gastrocnemius lateralis) concerning: a) Physical Properties (stiffness, tone and elasticity), assessed by MyotonPRO®; b) Strength, by a dynamometer; c) Mass, by bioimpedance; d) Performance through gait speed and 60-second sit-to-stand test; e) Histological and cellular/ molecular characterization through ultrasound-guided biopsies of multifidus muscle; f) Magnetic Resonance Imaging (MRI) characterization of paravertebral muscles. Furthermore, we will perform an integrated transcriptomics and proteomics analysis of peripheral blood samples. DISCUSSION: The innovative and multidisciplinary approaches of this project rely on the elucidation of myofascial physical properties in axSpA and also on the establishment of a biological signature that relates to specific muscle properties. This hitherto unstudied link between gene/protein signatures and muscle properties may enhance our understanding of axSpA physiopathology and reveal new and useful diagnostic and therapeutic targets.

Interdisciplinary consensus statements on imaging of scapholunate joint instability.

OBJECTIVES: The purpose of this agreement was to establish evidence-based consensus statements on imaging of scapholunate joint (SLJ) instability by an expert group using the Delphi technique. METHODS: Nineteen hand surgeons developed a preliminary list of questions on SLJ instability. Radiologists created statements based on the literature and the authors' clinical experience. Questions and statements were revised during three iterative Delphi rounds. Delphi panellists consisted of twenty-seven musculoskeletal radiologists. The panellists scored their degree of agreement to each statement on an eleven-item numeric scale. Scores of '0', '5' and '10' reflected complete disagreement, indeterminate agreement and complete agreement, respectively. Group consensus was defined as a score of '8' or higher for 80% or more of the panellists. RESULTS: Ten of fifteen statements achieved group consensus in the second Delphi round. The remaining five statements achieved group consensus in the third Delphi round. It was agreed that dorsopalmar and lateral radiographs should be acquired as routine imaging work-up in patients with suspected SLJ instability. Radiographic stress views and dynamic fluoroscopy allow accurate diagnosis of dynamic SLJ instability. MR arthrography and CT arthrography are accurate for detecting scapholunate interosseous ligament tears and articular cartilage defects. Ultrasonography and MRI can delineate most extrinsic carpal ligaments, although validated scientific evidence on accurate differentiation between partially or completely torn or incompetent ligaments is not available. CONCLUSIONS: Delphi-based agreements suggest that standardized radiographs, radiographic stress views, dynamic fluoroscopy, MR arthrography and CT arthrography are the most useful and accurate imaging techniques for the work-up of SLJ instability. KEY POINTS: • Dorsopalmar and lateral wrist radiographs remain the basic imaging modality for routine imaging work-up in patients with suspected scapholunate joint instability. • Radiographic stress views and dynamic fluoroscopy of the wrist allow accurate diagnosis of dynamic scapholunate joint instability. • Wrist MR arthrography and CT arthrography are accurate for determination of scapholunate interosseous ligament tears and cartilage defects.

Axial Spondyloarthritis: Mimics and Pitfalls of Imaging Assessment.

Axial spondyloarthritis (axSpA) is a chronic inflammatory disorder that predominantly involves the axial skeleton. Imaging findings of axSpA can be divided into active changes, which include bone marrow edema, synovitis, enthesitis, capsulitis, and intra-articular effusion, and structural changes, which include erosions, sclerosis, bone fatty infiltration, fat deposition in an erosion cavity, and bone bridging or ankylosis. The ability to distinguish between imaging lesions suggestive of axSpA and artifacts or lesions suggestive of other disorders is critical for the accurate diagnosis of axSpA. Diagnosis may be challenging, particularly in early-stage disease and magnetic resonance imaging (MRI) plays a key role in the detection of subtle or inflammatory changes. MRI also allows the detection of structural changes in the subchondral bone marrow that are not visible on conventional radiography and is of prognostic and monitoring value. However, bone structural changes are more accurately depicted using computed tomography. Conventional radiography, on the other hand, has limitations, but it is easily accessible and may provide insight on gross changes as well as rule out other pathological features of the axial skeleton. This review outlines the imaging evaluation of axSpA with a focus on imaging mimics and potential pitfalls when assessing the axial skeleton.

The Lisbon Agreement on femoroacetabular impingement imaging-part 2: general issues, parameters, and reporting.

OBJECTIVES: Imaging assessment for the clinical management of femoroacetabular impingement (FAI) is controversial because of a paucity of evidence-based guidance and notable variability among practitioners. Hence, expert consensus is needed because standardised imaging assessment is critical for clinical practice and research. We aimed to establish expert-based statements on FAI imaging by using formal methods of consensus building. METHODS: The Delphi method was used to formally derive consensus among 30 panel members from 13 countries. Forty-four questions were agreed upon, and relevant seminal literature was circulated and classified in major topics to produce answering statements. The level of evidence was noted for all statements, and panel members were asked to score their level of agreement (0-10). This is the second part of a three-part consensus series and focuses on 'General issues' and 'Parameters and reporting'. RESULTS: Forty-seven statements were generated and group consensus was reached for 45. Twenty-five statements pertaining to 'General issues' (9 addressing diagnosis, differential diagnosis, and postoperative imaging) and 'Parameters and reporting' (16 addressing femoral/acetabular parameters) were produced. CONCLUSIONS: The available evidence was reviewed critically, recommended criteria for diagnostic imaging highlighted, and the roles/values of different imaging parameters assessed. Radiographic evaluation (AP pelvis and a Dunn 45° view) is the cornerstone of hip-imaging assessment and the minimum imaging study that should be performed when evaluating adult patients for FAI. In most cases, cross-sectional imaging is warranted because MRI is the 'gold standard' imaging modality for the comprehensive evaluation, differential diagnosis assessment, and FAI surgical planning. KEY POINTS: • Diagnostic imaging for FAI is not standardised due to scarce evidence-based guidance on which imaging modalities and diagnostic criteria/parameters should be used. • Radiographic evaluation is the cornerstone of hip assessment and the minimum study that should be performed when assessing suspected FAI. Cross-sectional imaging is justified in most cases because MRI is the 'gold standard' modality for comprehensive FAI evaluation. • For acetabular morphology, coverage (Wiberg's angle and acetabular index) and version (crossover, posterior wall, and ischial spine signs) should be assessed routinely. On the femoral side, the head-neck junction morphology (α° and offset), neck morphology (NSA), and torsion should be assessed.

The Lisbon Agreement on Femoroacetabular Impingement Imaging-part 3: imaging techniques.

OBJECTIVES: Imaging diagnosis of femoroacetabular impingement (FAI) remains controversial due to a lack of high-level evidence, leading to significant variability in patient management. Optimizing protocols and technical details is essential in FAI imaging, although challenging in clinical practice. The purpose of this agreement is to establish expert-based statements on FAI imaging, using formal consensus techniques driven by relevant literature review. Recommendations on the selection and use of imaging techniques for FAI assessment, as well as guidance on relevant radiographic and MRI classifications, are provided. METHODS: The Delphi method was used to assess agreement and derive consensus among 30 panel members (musculoskeletal radiologists and orthopedic surgeons). Forty-four questions were agreed on and classified into five major topics and recent relevant literature was circulated, in order to produce answering statements. The level of evidence was assessed for all statements and panel members scored their level of agreement with each statement during 4 Delphi rounds. Either "group consensus," "group agreement," or "no agreement" was achieved. RESULTS: Forty-seven statements were generated and group consensus was reached for 45. Twenty-two statements pertaining to "Imaging techniques" were generated. Eight statements on "Radiographic assessment" and 12 statements on "MRI evaluation" gained consensus. No agreement was reached for the 2 "Ultrasound" related statements. CONCLUSION: The first international consensus on FAI imaging was developed. Researchers and clinicians working with FAI and hip-related pain may use these recommendations to guide, develop, and implement comprehensive, evidence-based imaging protocols and classifications. KEY POINTS: • Radiographic evaluation is recommended for the initial assessment of FAI, while MRI with a dedicated protocol is the gold standard imaging technique for the comprehensive evaluation of this condition. • The MRI protocol for FAI evaluation should include unilateral small FOV with radial imaging, femoral torsion assessment, and a fluid sensitive sequence covering the whole pelvis. • The definite role of other imaging methods in FAI, such as ultrasound or CT, is still not well defined.

Hip arthroscopy with initial access to the peripheral compartment provides significant improvement in FAI patients.

PURPOSE: This study was designed to evaluate the clinical and radiographic results of arthroscopic treatment of femoroacetabular impingement (FAI) using the technique of initial access to the peripheral compartment. It is based on a single surgeon large case series with a minimum of 2 years follow-up. METHODS: Prospective longitudinal study with consecutive patients. Inclusion criteria were the presence of FAI syndrome that had failed non-operative treatment and had a hip arthroscopy with initial access to the peripheral compartment. Exclusion criteria were previous hip surgery, patients younger than 16 or older than 60 years, Tönnis grade ≥ 2 osteoarthritis, hip dysplasia based on radiographic evidence of LCEA less than 25° and workers compensation cases. One hundred and sixty hips met the inclusion criteria, 84 were female and 70 were male patients (six bilateral cases), with a median age of 36 years (range 16-59). RESULTS: The median alpha angle correction was 22.6º (range 5.9-46.7) (p < 0.01) and the average LCEA correction when acetabuloplasty was undertaken was 6.5º (range - 1.4-20.8) (p < 0.01). The mean NAHS at baseline was 56.1 (range 16-96) and improved to 83.2 at the last follow up (range 44-100) for the patients that had no additional procedure (p < 0.01). The mean average improvement was 27.7º points (range - 16-73). No iatrogenic labral perforation and no full-thickness chondral damage were recorded during the arthroscopic procedures. CONCLUSIONS: Favourable outcomes are reported for the arthroscopic treatment of FAI with initial access to the peripheral compartment. The technique is protective against iatrogenic chondral and labral damage, more conservative to the joint capsule, but the mean traction time was relatively long when suture anchors were used. The results are comparable to the classic initial central compartment approach. LEVEL OF EVIDENCE: Level IV.

The dimensions of the hip labrum can be reliably measured using magnetic resonance and computed tomography which can be used to develop a standardized definition of the hypoplastic labrum.

PURPOSE: The purpose of this study was to examine the existing literature to determine the dimensions of the acetabular labrum, with a focus on hypotrophic labra, including the modalities and accuracy of measurement, factors associated with smaller labra, and any impacts on surgical management. METHODS: Four databases (PubMed, Ovid [MEDLINE], Cochrane Database, and EMBASE) were searched from database inception to January 2020. Two reviewers screened the literature independently and in duplicate. Methodological quality of included papers was assessed using the Methodological Index for Non-Randomized Studies (MINORS) criteria. Where possible, data on labral size were combined using a random effects model. RESULTS: Twenty-one studies (5 level II, 9 level III, 7 level IV) were identified. This resulted in 6,159 patients (6,436 hips) with a mean age of 34.3 years (range 8.4-85). The patients were 67.3% female with an average follow-up of 57.3 months. There was no consistent definition of labral size quoted throughout the literature. The mean width on MRI/MRA was 7.3 mm (95% CI 6.9-7.8 mm), on computed tomography arthrography was 8.7 mm (95% CI 8.0-9.3), and during arthroscopy was 5.0 mm (95% CI 4.9-5.2). Inter-observer reliability was good to excellent in all modalities. Labral hypotrophy may be associated with increased acetabular coverage. Hypertrophic labra were highly associated with acetabular dysplasia (r = - 0.706, - 0.596, - 0.504, respectively; P < 0.001). CONCLUSION: Labral width can reliably be measured utilizing imaging techniques including magnetic resonance and computed tomography. The pooled mean labral width was 6.2 mm, and height 4.6 mm. The establishment of a gold-standard of measurement on arthroscopy and advanced imaging would aid in clinical decision-making regarding treatment options for patients presenting with a painful hip, particularly those with hypoplastic labra, and provide radiological guidelines for standardized labrum size classifications. LEVEL OF EVIDENCE: Level IV.