The Lisbon Agreement on Femoroacetabular Impingement Imaging-part 1: overview

The different subtypes of cam morphology as defined by statistical shape modeling and their relationship with the development of hip osteoarthritis: A nationwide prospective cohort study (CHECK) with 10 years follow-up

OBJECTIVE

To determine if subtypes of cam morphology on anteroposterior radiographs exist using statistical shape modeling (SSM), and to assess their association with incident radiographic hip osteoarthritis (RHOA) within 10 years.

DESIGN

The nationwide prospective Cohort Hip and Cohort Knee (CHECK) study included 1002 participants aged 45-65 years with 10-year follow-up. Subtypes of cam morphology were defined as SSM-based shape variations of femoral head-neck junction that are associated with baseline cam morphology (alpha angle ≥60°). The association between each subtype in hips free of osteoarthritis at baseline (Kellgren & Lawrence (KL) grade <2) and incident RHOA (KL grade≥2, or a total hip replacement) was estimated using logistic regression at 10-year follow-up and stratified by sex.

RESULTS

In sex-combined group, but also for males and females separately, cam morphology subtypes were captured in modes 1, 3, 4, and 5 with odds ratios (ORs) ranging from 0.39 (0.27-0.58) to 2.25 (1.64-3.10). For sex-combined group, only mode 3, a flattened head-neck junction, was associated with incident RHOA (OR:1.14, 1.02-1.27). Males' modes 1 and 3 and females' modes 3 and 4 were associated with RHOA. Notably, the female mode 4, a slightly flattened neck but with subtle curvature, was significantly protective for RHOA (OR:0.88, 0.80-0.98).

CONCLUSIONS

We identified four distinct morphological subtypes of cam morphology defined by alpha angle. Only some subtypes were found acting as risk factors for RHOA at 10-year follow-up, which differed between males and females. This highlights the need to study cam morphology beyond the alpha angle alone.

Are hip joint imaging findings associated with symptoms and early hip osteoarthritis features in elite male Australian Football League draftees?

1) describe intra-articular features (prevalence and severity) and bony hip morphology (prevalence and size) in elite male Australia Football League (AFL) draftees; 2) examine the relationship between bony hip morphology (cam and pincer morphology) and intra-articular features (cartilage defects and labral tears); and 3) examine the relationship between intra-articular features, bony hip morphology, and the Copenhagen Hip and Groin Outcome Score (HAGOS). Cross-sectional study. 58 male AFL draftees underwent 3-tesla hip MRI. Alpha angle determined cam morphology and acetabular depth defined pincer morphology. For each hip, intra-articular features were scored semi-quantitatively. All players completed the HAGOS to determine hip/groin symptoms and sports function. Logistic regression determined whether bony hip morphology was associated with labral tears and cartilage defects. Mann-Whitney U tests evaluated the difference in HAGOS subscale scores between football players with and without intra-articular features and bony hip morphology. Cam and pincer morphology were evident in 20% and 19% of hips, respectively. Nearly half of hips (41%) had a labral tear, with only 14% having a cartilage defect. Greater alpha angle was associated with the presence of labral tears (OR 1.14, 95%CI 1.07 to 1.21, p < 0.001) but not cartilage defects. Hip imaging findings were not associated with lower (worse) HAGOS scores. Hip joint imaging findings were common in elite male AFL draftees but not associated with worse pain, symptoms, or sport function. Cam morphology may contribute to the development of labral tears in male AFL draftees.

Femoral head decentration on hip MRI: comparison between imaging planes, methods of contrast administration, and hip deformities

OBJECTIVES

To compare the prevalence of femoral head decentration (FHD) on different MR imaging planes in patients undergoing direct/indirect hip MR arthrography (MRA) with asymptomatic controls and to evaluate its association with osseous deformities.

METHODS

IRB-approved retrospective single-center study of symptomatic hips undergoing direct or indirect hip MRA at 3 T. Asymptomatic participants underwent non-contrast hip MRI at 3 T. FHD was defined as a continuous fluid layer between the acetabulum and femoral head and assessed on axial, sagittal and radial images. The association of intra-articular/intra-venous contrast agents and the prevalence of FHD was evaluated. The association of FHD with osseous deformities and joint damage was assessed using multiple logistic regression analysis.

RESULTS

Three-hundred ninety-four patients (447 hips, mean age 31 ± 9 years, 247 females) were included and compared to 43 asymptomatic controls (43 hips, mean age 31 ± 6 years, 26 females). FHD was most prevalent on radial images and more frequent in symptomatic hips (30% versus 2%, p < 0.001). FHD prevalence was not associated with the presence/absence of intra-articular contrast agents (30% versus 22%, OR = 1.5 (95% CI 0.9-2.5), p = 0.125). FHD was associated with hip dysplasia (OR = 6.1 (3.3-11.1), p < 0.001), excessive femoral torsion (OR = 3.0 (1.3-6.8), p = 0.010), and severe cartilage damage (OR = 3.6 (2.0-6.7), p < 0.001).

CONCLUSION

While rare in asymptomatic patients, femoral head decentration in symptomatic patients is associated with osseous deformities predisposing to hip instability, as well as with extensive cartilage damage.

CRITICAL RELEVANCE STATEMENT

Decentration of the femoral head on radial MRA may be interpreted as a sign of hip instability in symptomatic hips without extensive cartilage defects. Its presence could unmask hip instability and yield promise in surgical decision-making.

KEY POINTS

The best method of identifying femoral head decentration is radial MRI. The presence/absence of intra-articular contrast is not associated with femoral head decentration. Femoral head decentration is associated with hip deformities predisposing to hip instability.

Imaging of Disease and Normal Variant Patterns in Pediatric Hips

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

Soft tissue tumor imaging in adults: whole-body staging in sarcoma, non-malignant entities requiring special algorithms, pitfalls and special imaging aspects. Guidelines 2024 from the European Society of Musculoskeletal Radiology (ESSR)

OBJECTIVES

The revised European Society of Musculoskeletal Radiology (ESSR) consensus guidelines on soft tissue tumor imaging represent an update of 2015 after technical advancements, further insights into specific entities, and revised World Health Organization (2020) and AJCC (2017) classifications. This second of three papers covers algorithms once histology is confirmed: (1) standardized whole-body staging, (2) special algorithms for non-malignant entities, and (3) multiplicity, genetic tumor syndromes, and pitfalls.

MATERIALS AND METHODS

A validated Delphi method based on peer-reviewed literature was used to derive consensus among a panel of 46 specialized musculoskeletal radiologists from 12 European countries. Statements that had undergone interdisciplinary revision were scored online by the level of agreement (0 to 10) during two iterative rounds, that could result in 'group consensus', 'group agreement', or 'lack of agreement'.

RESULTS

The three sections contain 24 statements with comments. Group consensus was reached in 95.8% and group agreement in 4.2%. For whole-body staging, pulmonary MDCT should be performed in all high-grade sarcomas. Whole-body MRI is preferred for staging bone metastasis, with [18F]FDG-PET/CT as an alternative modality in PET-avid tumors. Patients with alveolar soft part sarcoma, clear cell sarcoma, and angiosarcoma should be screened for brain metastases. Special algorithms are recommended for entities such as rhabdomyosarcoma, extraskeletal Ewing sarcoma, myxoid liposarcoma, and neurofibromatosis type 1 associated malignant peripheral nerve sheath tumors. Satisfaction of search should be avoided in potential multiplicity.

CONCLUSION

Standardized whole-body staging includes pulmonary MDCT in all high-grade sarcomas; entity-dependent modifications and specific algorithms are recommended for sarcomas and non-malignant soft tissue tumors.

CLINICAL RELEVANCE STATEMENT

These updated ESSR soft tissue tumor imaging guidelines aim to provide support in decision-making, helping to avoid common pitfalls, by providing general and entity-specific algorithms, techniques, and reporting recommendations for whole-body staging in sarcoma and non-malignant soft tissue tumors.

KEY POINTS

An early, accurate, diagnosis is crucial for the prognosis of patients with soft tissue tumors. These updated guidelines provide best practice expert consensus for standardized imaging algorithms, techniques, and reporting. Standardization can improve the comparability examinations and provide databases for large data analysis.

Imaging Modalities in the Preoperative Assessment of Femoroacetabular Impingement and Hip Dysplasia: Determining Best Practices

» In the last decade, significant progress has been made in understanding hip pain, especially related to femoroacetabular impingement (FAI) and hip dysplasia (HD), which collectively affect over 20% of the population.» Preoperative imaging, including plain radiographs, computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound (US), plays a pivotal role in diagnosing FAI and HD. Imaging precision, standardized techniques, and accurate interpretation are crucial for effective treatment planning.» The continual advancements in imaging techniques, especially seen in MRI (arthrograms, application of leg traction, and delayed gadolinium-enhanced MRI of cartilage), represent important strides in the precise assessment of pathology associated with FAI and HD.» By incorporating these advancements into routine imaging protocols, healthcare providers can ensure a comprehensive understanding of hip joint dynamics, enabling more accurate diagnosis and effective management strategies for patients with FAI and HD, ultimately leading to improved clinical outcomes.

Prevalence and radiological definitions of acetabular dysplasia after the age of 2 years: a systematic review

Acetabular dysplasia is one of the most common causes of early hip osteoarthritis and hip replacement surgery. Recent literature suggests that acetabular dysplasia does not always originate at infancy, but can also develop later during childhood. This systematic review aims to appraise the literature on prevalence numbers of acetabular dysplasia in children after the age of 2 years. A systematic search was performed in several scientific databases. Publications were considered eligible for inclusion if they presented prevalence numbers on acetabular dysplasia in a general population of healthy children aged 2-18 years with description of the radiological examination. Quality assessment was done using the Newcastle-Ottawa score. Acetabular dysplasia was defined mild when: the center-edge angle of Wiberg (CEA-W) measured 15-20°, the CEA-W ranged between -1 to -2SD for age, or based on the acetabular index using thresholds from the Tönnis table. Severe dysplasia was defined by a CEA-W < 15°, <-2SD for age, or acetabular index according to Tönnis. Of the 1837 screened articles, four were included for review. Depending on radiological measurement, age and reference values used, prevalence numbers for mild acetabular dysplasia vary from 13.4 to 25.6% and for severe acetabular dysplasia from 2.2 to 10.9%. Limited literature is available on prevalence of acetabular dysplasia in children after the age of 2 years. Prevalence numbers suggest that acetabular dysplasia is not only a condition in infants but also highly prevalent later in childhood.

Soft tissue tumor imaging in adults: European Society of Musculoskeletal Radiology-Guidelines 2023-overview, and primary local imaging: how and where?

OBJECTIVES

Early, accurate diagnosis is crucial for the prognosis of patients with soft tissue sarcomas. To this end, standardization of imaging algorithms, technical requirements, and reporting is therefore a prerequisite. Since the first European Society of Musculoskeletal Radiology (ESSR) consensus in 2015, technical achievements, further insights into specific entities, and the revised WHO-classification (2020) and AJCC staging system (2017) made an update necessary. The guidelines are intended to support radiologists in their decision-making and contribute to interdisciplinary tumor board discussions.

MATERIALS AND METHODS

A validated Delphi method based on peer-reviewed literature was used to derive consensus among a panel of 46 specialized musculoskeletal radiologists from 12 European countries. Statements were scored online by level of agreement (0 to 10) during two iterative rounds. Either "group consensus," "group agreement," or "lack of agreement" was achieved.

RESULTS

Eight sections were defined that finally contained 145 statements with comments. Overall, group consensus was reached in 95.9%, and group agreement in 4.1%. This communication contains the first part consisting of the imaging algorithm for suspected soft tissue tumors, methods for local imaging, and the role of tumor centers.

CONCLUSION

Ultrasound represents the initial triage imaging modality for accessible and small tumors. MRI is the modality of choice for the characterization and local staging of most soft tissue tumors. CT is indicated in special situations. In suspicious or likely malignant tumors, a specialist tumor center should be contacted for referral or teleradiologic second opinion. This should be done before performing a biopsy, without exception.

CLINICAL RELEVANCE

The updated ESSR soft tissue tumor imaging guidelines aim to provide best practice expert consensus for standardized imaging, to support radiologists in their decision-making, and to improve examination comparability both in individual patients and in future studies on individualized strategies.

KEY POINTS

• Ultrasound remains the best initial triage imaging modality for accessible and small suspected soft tissue tumors. • MRI is the modality of choice for the characterization and local staging of soft tissue tumors in most cases; CT is indicated in special situations. Suspicious or likely malignant tumors should undergo biopsy. • In patients with large, indeterminate or suspicious tumors, a tumor reference center should be contacted for referral or teleradiologic second opinion; this must be done before a biopsy.

Are degenerative findings detected on traction MR arthrography of the hip associated with failure of arthroscopic femoroacetabular impingement surgery?

OBJECTIVES

To identify preoperative degenerative features on traction MR arthrography associated with failure after arthroscopic femoroacetabular impingement (FAI) surgery.

METHODS

Retrospective study including 102 patients (107 hips) undergoing traction magnetic resonance arthrography (MRA) of the hip at 1.5 T and subsequent hip arthroscopic FAI surgery performed (01/2016 to 02/2020) with complete follow-up. Clinical outcomes were assessed using the International Hip Outcome Tool (iHOT-12) score. Clinical endpoint for failure was defined as an iHOT-12 of < 60 points or conversion to total hip arthroplasty. MR images were assessed by two radiologists for presence of 9 degenerative lesions including osseous, chondrolabral/ligamentum teres lesions. Uni- and multivariate Cox regression analysis was performed to assess the association between MRI findings and failure of FAI surgery.

RESULTS

Of the 107 hips, 27 hips (25%) met at least one endpoint at a mean 3.7 ± 0.9 years follow-up. Osteophytic changes of femur or acetabulum (hazard ratio [HR] 2.5-5.0), acetabular cysts (HR 3.4) and extensive cartilage (HR 5.1) and labral damage (HR 5.5) > 2 h on the clockface were univariate risk factors (all p < 0.05) for failure. Three risk factors for failure were identified in multivariate analysis: Acetabular cartilage damage > 2 h on the clockface (HR 3.2, p = 0.01), central femoral osteophyte (HR 3.1, p = 0.02), and femoral cartilage damage with ligamentum teres damage (HR 3.0, p = 0.04).

CONCLUSION

Joint damage detected by preoperative traction MRA is associated with failure 4 years following arthroscopic FAI surgery and yields promise in preoperative risk stratification.

CLINICAL RELEVANCE STATEMENT

Evaluation of negative predictors on preoperative traction MR arthrography holds the potential to improve risk stratification based on the already present joint degeneration ahead of FAI surgery.

KEY POINTS

• Osteophytes, acetabular cysts, and extensive chondrolabral damage are risk factors for failure of FAI surgery. • Extensive acetabular cartilage damage, central femoral osteophytes, and combined femoral cartilage and ligamentum teres damage represent independent negative predictors. • Survival rates following hip arthroscopy progressively decrease with increasing prevalence of these three degenerative findings.

Direct MR arthrography without image guidance: a practical guide, joint-by-joint

Direct MR arthrography (dMRA) is a fundamental technique in diagnosing pathology in major peripheral joints, allowing for precise evaluation of intra-articular structures. Although injection guidance is typically performed using imaging techniques such as ultrasound or fluoroscopy, puncture via anatomical landmarks may be useful in certain circumstances where it has been proven to be a safe and effective procedure. This paper describes the indications and injection technique of dMRA, joint by joint, focusing on the different technical details, from the most common locations, like the shoulder or hip, to those with more restricted clinical indications, such as the wrist, knee, elbow, or ankle. The most relevant anatomical landmarks are detailed for each joint, aiding in the intra-articular introduction of diluted contrast, highlighting the most accessible trajectories and structures to avoid when inserting the needle. Additionally, tips are provided to facilitate proper joint distension. With all this information, this paper aims to serve as a suitable reference guide for performing dMRA without image guidance if needed.

Canadian Association of Radiologists Musculoskeletal System Diagnostic Imaging Referral Guideline

The Canadian Association of Radiologists (CAR) Musculoskeletal System Expert Panel consists of musculoskeletal radiologists, a family physician, a sports and exercise medicine physician, emergency medicine physicians, a patient advisor, and an epidemiologist/guideline methodologist. After developing a list of 25 musculoskeletal clinical/diagnostic scenarios, a systematic rapid scoping review was undertaken to identify systematically produced referral guidelines that provide recommendations for 1 or more of these clinical/diagnostic scenarios. Recommendations from 41 guidelines (50 publications) and contextualization criteria in the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) for guidelines framework were used to develop 124 recommendation statements across the 25 scenarios related to the evaluation of the musculoskeletal system. This guideline presents the methods of development and the recommendations for imaging in the context of musculoskeletal pain, infection, tumors, arthropathies, metabolic bone disease, stress injuries, orthopedic hardware, avascular necrosis/bone infarction, and complex regional pain syndrome.

Impact of gadolinium-based MRI contrast agent and local anesthetics co-administration on chondrogenic gadolinium uptake and cytotoxicity

The gadolinium-based contrast agent DOTA-Gd is clinically used in combination with local anesthetics for direct magnetic resonance arthrography. It remains unclear whether gadolinium uptake into cartilage is influenced by co-administration of bupivacaine or ropivacaine and whether DOTA-Gd alters their chondrotoxicity. Gadolinium quantification of chondrogenic spheroids revealed enhanced gadolinium uptake after simultaneous exposure to local anesthetics. Analyses of the spatial gadolinium distribution using synchrotron X-ray-fluorescence scanning indicates gadolinium exposed chondrocytes. In vitro exposure to DOTA-Gd does not alter viability and proliferation of human chondrocytes and the chondrotoxic potential of the anesthetics. Reduced viability induced by ropivacaine was found to be reversible, while exposure to bupivacaine leads to irreversible cell death. Our data suggest that ropivacaine is more tolerable than bupivacaine and that DOTA-Gd exposure does not alter the cytotoxicity of both anesthetics. Enhanced gadolinium uptake into cartilage due to co-administration of anesthetics should find attention.

Direct MR arthrography of the hip joint: anterior approach without imaging guidance

PURPOSE

The purpose of this study is to describe the anterior injection approach, with anatomical landmark guidance, for direct MR arthrography (dMRA) of the hip joint, and to evaluate the effectiveness in joint distension and the security of the technique.

MATERIAL AND METHODS

Retrospective review of hip dMRAs was conducted on patients with suspected intra-articular pathology from two MR outpatient centers, performed by two radiologists with 25 and 5 years of experience, respectively. The analysis included assessing the presence of intra-articular contrast material (gadolinium-based solution), the number of injections performed, the degree of joint distension, and the degree of contrast extravasation. A multi-variant analysis was carried out to determine if the procedure success depend on any of the demographic variants or on the radiologist experience. Additionally, the presence of immediate and medium-term post-puncture complications was evaluated.

RESULTS

One hundred patients with 104 hip dMRA were included; 60 were men, with mean age of 38 years (16-63 years). Contrast material was successfully introduced intra-articularly in 100% of patients, being necessary a second puncture only in 6% of procedures. The capsular distension was considered optimal for diagnosis in 97% of cases. Different degrees of contrast extravasation were found in 30% of dMRA. There was no statistically significant relationship observed between patient variables and the performance of dMRA, nor did it show any correlation with the experience of the radiologists. No puncture-derived complications were found.

CONCLUSION

Hip dMRA through anterior injection guided by anatomical references is an effective and safe alternative for patients with suspected intra-articular pathology.

Femoroacetabular impingement - What the rheumatologist needs to know

Femoroacetabular impingement (FAI) syndrome is a common cause of hip and groin pain in young individuals. FAI syndrome is a triad of signs, symptoms, and imaging findings. Necessary but not sufficient for the diagnosis of FAI syndrome is the presence of cam and/or pincer morphology of the hip. However, pathological thresholds for cam and pincer morphologies are not well-established. Management of FAI syndrome is typically through either physiotherapist-led therapy or surgical intervention. Physiotherapist-led management involves exercises aimed to optimise movement patterns of the hip and pelvis to prevent impingement from occurring, activity modification and analgesia, whereas surgical management involves arthroscopic resection of the cam/pincer morphology and treatment of concomitant soft tissue pathologies such as labral tears, cartilage lesions or ligamentum teres tears. Careful consideration of intervention is required given that FAI syndrome may predispose those affected to developing future osteoarthritis of the hip. In most clinical trials, hip arthroscopy has been found to provide greater improvement in patient-reported outcomes in the short-term compared to physiotherapy, however it is unknown whether this is sustained in the long-term or affects the future development of hip osteoarthritis.

Discrepancies in MR- and CT-Based Femoral Version Measurements Despite Strong Correlations

PURPOSE

To determine the correlation and classification consistency of femoral version measurements between magnetic resonance (MR) and computed tomography (CT) using 4 commonly used measurement methods.

METHODS

A retrospective study was performed on patients with femoroacetabular impingement (FAI) who received preoperative CT and MR imaging assessment of the surgical hip and ipsilateral distal femur. Femoral version was measured using the Murphy method, the oblique method, the Reikerås method, and the Lee method. Intra- and inter-rater agreements were calculated. Linear regression and Bland-Altman analysis were performed for measurements using different imaging modalities and measurement methods. Femoral version measurements within the lower quartile, the middle 2 quartiles, and the upper quartile were classified into different groups based on their percentile within the sample population. Classification consistency rates between modalities and methods were calculated and compared.

RESULTS

Fifty-three patients (39.4 ± 9.1 years; 32 female) were included for analysis. Intra- and inter-rater reliability were high for all modalities and methods (intrarater intraclass correlation coefficient [ICC] range, 0.963-0.993; inter-rater ICC range, 0.871-0.960). MR- and CT-based femoral version measurements showed strong correlations for all methods, with the Lee method demonstrating the strongest association (r = 0.904), while the oblique method exhibited the lowest correlation (r = 0.684) (all P < .001). MR-based measurements were smaller than CT-based measurements, with mean differences ranging from 4.5° to 10.3°. Classification consistency between MR and CT ranged from 51% to 74%, whereas the consistency between different measurement methods ranged from 68% to 85%.

CONCLUSIONS

While strong correlations were observed between MR- and CT-based femoral version measurements, MR-based measurements were significantly smaller than their CT counterparts. Classification consistency between the modalities was moderate to high. Measurements between different methods showed strong correlations with high consistency rates.

LEVEL OF EVIDENCE

Level III, retrospective case series.

Osteoarthritis of the hip: is radiography still needed?

Diagnosis of hip osteoarthritis (OA) is based on clinical arguments, and medical imaging is obtained to confirm the diagnosis and rule out other possible sources of pain. Conventional radiographs are recommended as the first line imaging modality to investigate chronic hip pain. They should be obtained in a rigorous technique that includes an antero-posterior (AP) radiograph of the pelvis. The choice of the appropriate lateral view depends on the clinical indication, Lequesne's false profile being valuable in the assessment of OA. Magnetic resonance imaging (MRI) is more sensitive to detect joint effusion/synovitis, cartilage, labral, and bone marrow lesions. However, structural joint changes are frequent in asymptomatic population and neither radiographs nor MRI have shown a good correlation with pain and functional impairment. MRI seems to be more suitable than radiographs as a biomarker for clinical trials addressing early OA. The absence of a validated MR biomarker of early OA, together with issues related to machine availability and MRI protocol repeatability, prevent the widespread use of MRI in clinical trials.

Hip MRI in flexion abduction external rotation for assessment of the ischiofemoral interval in patients with hip pain-a feasibility study

OBJECTIVES

To assess the feasibility of flexion-abduction-external rotation (FABER) magnetic resonance imaging (MRI) of the hip to visualize changes in the ischiofemoral interval and ability to provoke foveal excursion over the acetabular rim.

METHODS

IRB-approved retrospective single-center study. Patients underwent non-contrast 1.5-T hip MRI in the neutral and FABER position. Two readers measured the ischiofemoral interval at three levels: proximal/distal intertrochanteric distance and ischiofemoral space. Subgroup analysis was performed for hips with/without high femoral torsion, or quadratus femoris muscle edema (QFME), respectively. A receiver operating curve with calculation of the area under the curve (AUC) for the prediction of QFME was calculated. The presence of foveal excursion in both positions was assessed.

RESULTS

One hundred ten patients (121 hips, mean age 34 ± 11 years, 67 females) were evaluated. FABER-MRI led to narrowing (both p < .001) of the ischiofemoral interval which decreased more at the proximal (mean decrease by 26 ± 7 mm) than at the distal (6 ± 7 mm) intertrochanteric ridge. With high femoral torsion/ QFME, the ischiofemoral interval was significantly narrower at all three measurement locations compared to normal torsion/no QFME (p < .05). Accuracy for predicting QFME was high with an AUC of .89 (95% CI .82-.94) using a threshold of ≤ 7 mm for the proximal intertrochanteric distance. With FABER-MRI foveal excursion was more frequent in hips with QFME (63% vs 25%; p = .021).

CONCLUSION

Hip MRI in the FABER position is feasible, visualizes narrowing of the ischiofemoral interval, and can provoke foveal excursion.

CRITICAL RELEVANCE STATEMENT

FABER MRI may be helpful in diagnosing ischiofemoral impingement and detecting concomitant hip instability by overcoming shortcomings of static MR protocols that do not allow visualization of dynamic changes in the ischiofemoral interval and thus may improve surgical decision making.

KEY POINTS

• FABER MRI enables visualization of narrowing of the ischiofemoral interval proximal to the lesser trochanter. • Proximal intertrochanteric distance of ≤ 7 mm accurately predicts quadratus femoris muscle edema. • Foveal excursion was more frequent in hips with quadratus femoris muscle edema.

Does response to preoperative intra-articular anesthetic injections predict outcomes of femoroacetabular impingement syndrome?

INTRODUCTION

Some patients with femoroacetabular impingement syndrome (FAIS) who undergo surgery do not show satisfactory outcomes. Reliable tests that can inform prognosis of FAIS surgery are needed for optimized indications and contraindications to surgery. We aimed to review and critically appraise available literature on the capability of patient response to preoperative intra-articular anesthetic injections (PIAI) to predict post-surgical outcomes in patients with FAIS.

MATERIALS AND METHODS

This study was conducted in accordance with the PRISMA statement. Studies that assessed the patient pain response to PIAI and post-surgical outcomes in patients with FAIS were considered eligible. Study selection and data collection were performed by three independent reviewers. Main outcomes evaluated were those measured by hip outcome scales often used in assessing postoperative pain and functional recovery, such as the modified Harris Hip Score (mHHS) and international Hip Outcome Tool (iHOT). The likelihood ratio of achieving satisfactory postoperative outcomes at the mHHS (LHR) was extracted or calculated-for patients with significant response to PIAI and for those without a significant response to PIAI. The risk of bias was assessed using the Quality In Prognosis Studies (QUIPS) tool.

RESULTS

Six studies were considered eligible for analysis. Five studies indicated that patient response to PIAI are associated to surgical outcomes for patients with FAIS, with a greater reduction in pain typically indicating a better surgical outcome. Additionally, the LHR ranged from 1.15 to 1.92 for patients with significant response to PIAI (I2 = 90.6%). For patients without a significant response, the LHR ranged from 0.18 to 0.65 (I2 = 87.5). An overall high risk of bias was observed for all studies included in the analysis. Study attrition, the prognostic factor measurement and the presence of confounding factors were the main sources of bias.

CONCLUSIONS

Greater reductions in pain with preoperative intra-articular anesthetic injections were found to be associated to better outcomes after FAIS surgery, but all available studies contain a high risk of bias.

[Femoroacetabular impingement in adolescents]

Femoroacetabular impingement syndrome (FAIS) is caused by a repetitive mechanical conflict between the acetabulum and the proximal femur, occurring in flexion and internal rotation. In cam impingement, bony prominences of the femoral head-neck junction induce chondrolabral damage. The acetabular type of FAIS, termed pincer FAIS, may be either due to focal or global retroversion and/or acetabular overcoverage. Combinations of cam and pincer morphology are common. Pathological femoral torsion may aggravate or decrease the mechanical conflict in FAI but can also occur in isolation. Of note, a high percentage of adolescents with FAI-like shape changes remain asymptomatic. The diagnosis of FAIS is therefore made clinically, whereas imaging reveals the underlying morphology. X‑rays in two planes remain the primary imaging modality, the exact evaluation of the osseous deformities of the femur and chondrolabral damage is assessed by magnetic resonance imaging (MRI). Acetabular coverage and version are primarily assessed on radiographs. Evaluation of the entire circumference of the proximal femur warrants MRI which is further used in the assessment of chondrolabral lesions, and also bone marrow and adjacent soft tissue abnormalities. The MRI protocol should routinely include measurements of femoral torsion. Fluid-sensitive sequences should be acquired to rule out degenerative or inflammatory extra-articular changes.

Anterior and Lateral Femoroacetabular Excursion Angles Are Helpful for Assessing Femoroacetabular Impingement Syndrome: A Cross-Sectional Cohort Study

PURPOSE

To develop a radiographic measurement to evaluate the femoroacetabular space using 3-dimensional (3D) hip models in asymptomatic hips, and to evaluate the reliability and validity of the femoroacetabular excursion angle (FAEA) in symptomatic patients.

METHODS

From January 2020 to December 2020, we recruited patients with healthy hips to establish 3D models. Through the simulation of 14 activities of daily living (ADLs), anterior and lateral impingement-free FAEAs were measured. Another cross-sectional cohort was formed from consecutive symptomatic subjects with impingement signs during the same period. In the validation cohort, anterior and lateral FAEAs were assessed on modified Dunn's and anteroposterior views of the hip, respectively. We evaluated the reliability and clinical implications of the FAEAs.

RESULTS

In the discovery cohort (n = 33), hips with collisions tended to have smaller computed tomography-based FAEAs than collision-free hips, although alpha and lateral center-edge (CE) angles were comparable. Additionally, hips with a lower quartile of FAEAs had a significantly higher number of ADLs with collisions. In the validation cohort (n = 411), the FAEA measurement was highly reliable (kappa statistics >0.95 for both interobserver and intraobserver reliabilities). The femoroacetabular impingement syndrome (FAIS) group (n = 165) showed significantly smaller anterior and lateral FAEAs than the non-FAIS group (all P < .001, Cramer V = .420). The optimal cut-off values for anterior and lateral FAEAs were 32.6° and 48.9°, respectively. In univariate regression, anterior (odds ratio [OR] = 0.91; 95% confidence interval [CI] = 0.89-0.94) and lateral (OR = 0.91; 95% CI = 0.89-0.93) FAEAs were significantly associated with FAIS. Moreover, in multivariate regression adjusted for alpha and lateral CE angles, anterior FAEA remained a significant predictor (OR = 0.96; 95% CI = 0.93-0.99), and small FAEA was an independent risk factor for FAIS (OR = 1.99; 95% CI = 1.06-3.71) for any small FAEA (OR = 2.88; 95% CI = 1.32-6.31) for both small FAEAs.

CONCLUSION

The FAEA is a valid measurement for FAIS with high reliability. Small FAEA was an independent risk factor for FAIS in the multivariate regression model, even after adjusting for alpha and lateral CE angles.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Can gadolinium contrast agents be replaced with saline for direct MR arthrography of the hip? A pilot study with arthroscopic comparison

OBJECTIVE

To compare image quality and diagnostic performance of preoperative direct hip magnetic resonance arthrography (MRA) performed with gadolinium contrast agent and saline solution.

METHODS

IRB-approved retrospective study of 140 age and sex-matched symptomatic patients with femoroacetabular impingement, who either underwent intra-articular injection of 15-20 mL gadopentetate dimeglumine (GBCA), 2.0 mmol/L ("GBCA-MRA" group, n = 70), or 0.9% saline solution ("Saline-MRA" group, n = 70) for preoperative hip MRA and subsequent hip arthroscopy. 1.5 T hip MRA was performed including leg traction. Two readers assessed image quality using a 5-point Likert scale (1-5, excellent-poor), labrum and femoroacetabular cartilage lesions. Arthroscopic diagnosis was used to calculate diagnostic accuracy which was compared between groups with Fisher's exact tests. Image quality was compared with the Mann-Whitney U tests.

RESULTS

Mean age was 33 years ± 9, 21% female patients. Image quality was excellent (GBCA-MRA mean range, 1.1-1.3 vs 1.1-1.2 points for Saline-MRA) and not different between groups (all p > 0.05) except for image contrast which was lower for Saline-MRA group (GBCA-MRA 1.1 ± 0.4 vs Saline-MRA 1.8 ± 0.5; p < 0.001). Accuracy was high for both groups for reader 1/reader 2 for labrum (GBCA-MRA 94%/ 96% versus Saline-MRA 96%/93%; p > 0.999/p = 0.904) and acetabular (GBCA-MRA 86%/ 83% versus Saline-MRA 89%/87%; p = 0.902/p = 0.901) and femoral cartilage lesions (GBCA-MRA 97%/ 99% versus Saline-MRA 97%/97%; both p > 0.999).

CONCLUSION

Diagnostic accuracy and image quality of Saline-MRA and GBCA-MRA is high in assessing chondrolabral lesions underlining the potential role of non-gadolinium-based hip MRA.

KEY POINTS

• Image quality of Saline-MRA and GBCA-MRA was excellent for labrum, acetabular and femoral cartilage, ligamentum teres, and the capsule (all p > 0.18). • The overall image contrast was lower for Saline-MRA (Saline-MRA 1.8 ± 0.5 vs. GBCA-MRA 1.1 ± 0.4; p < 0.001). • Diagnostic accuracy was high for Saline-MRA and GBCA-MRA for labrum (96% vs. 94%; p > 0.999), acetabular cartilage damage (89% vs. 86%; p = 0.902), femoral cartilage damage (97% vs. 97%; p > 0.999), and extensive cartilage damage (97% vs. 93%; p = 0.904).

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.

Stratified care in hip arthroscopy: can we predict successful and unsuccessful outcomes? Development and external temporal validation of multivariable prediction models

OBJECTIVE

Although hip arthroscopy is a widely adopted treatment option for hip-related pain, it is unknown whether preoperative clinical information can be used to assist surgical decision-making to avoid offering surgery to patients with limited potential for a successful outcome. We aimed to develop and validate clinical prediction models to identify patients more likely to have an unsuccessful or successful outcome 1 year post hip arthroscopy based on the patient acceptable symptom state.

METHODS

Patient records were extracted from the Danish Hip Arthroscopy Registry (DHAR). A priori, 26 common clinical variables from DHAR were selected as prognostic factors, including demographics, radiographic parameters of hip morphology and self-reported measures. We used 1082 hip arthroscopy patients (surgery performed 25 April 2012 to 4 October 2017) to develop the clinical prediction models based on logistic regression analyses. The development models were internally validated using bootstrapping and shrinkage before temporal external validation was performed using 464 hip arthroscopy patients (surgery performed 5 October 2017 to 13 May 2019).

RESULTS

The prediction model for unsuccessful outcomes showed best and acceptable predictive performance on the external validation dataset for all multiple imputations (Nagelkerke R2 range: 0.25-0.26) and calibration (intercept range: -0.10 to -0.11; slope range: 1.06-1.09), and acceptable discrimination (area under the curve range: 0.76-0.77). The prediction model for successful outcomes did not calibrate well, while also showing poor discrimination.

CONCLUSION

Common clinical variables including demographics, radiographic parameters of hip morphology and self-reported measures were able to predict the probability of having an unsuccessful outcome 1 year after hip arthroscopy, while the model for successful outcome showed unacceptable accuracy. The externally validated prediction model can be used to support clinical evaluation and shared decision making by informing the orthopaedic surgeon and patient about the risk of an unsuccessful outcome, and thus when surgery may not be appropriate.

Anterior Center-Edge Angle Is Less Reliable Than Anterior Wall Index to Predict Anterior Coverage of the Femoral Head

BACKGROUND

No consensus is available regarding which radiographic measurement most accurately correlates with anterior coverage of the femoral head.

PURPOSE

(1) To determine the correlation between 2 measurements of anterior wall coverage: total anterior coverage (TAC) calculated from radiographs and equatorial anterior acetabular sector angle (eAASA) calculated from computed tomography (CT) scans; (2) to define the correlation between anterior center-edge angle (ACEA) and anterior wall index (AWI) with TAC and eAASA; and (3) to investigate what other radiographic metrics may help predict anterior coverage.

STUDY DESIGN

Cohort study (Diagnosis); Level of evidence, 3.

METHODS

The authors retrospectively reviewed 77 hips (48 patients) for which radiographs and CT scans were obtained for reasons other than hip-related pain. Mean age of the population was 62 ± 22 years; 48 (62%) hips were from female patients. Two observers measured lateral center-edge angle (LCEA), AWI, Tönnis angle, ACEA, CT-based pelvic tilt, and CT-based acetabular version, with all Bland-Altman plots within 95% agreement. Correlation between intermethod measurements was estimated with a Pearson coefficient. Linear regression was used to test the ability of baseline radiographic measurements to predict both TAC and eAASA.

RESULTS

Pearson coefficients were r = 0.164 (ACEA vs TAC; P = .155), r = 0.170 (ACEA vs eAASA; P = .140), r = 0.58 (AWI vs TAC; P = .0001), and r = 0.693 (AWI vs eAASA; P < .0001). Multiple linear regression model 1 showed that AWI (β = 17.8; 95% CI, 5.7 to 29.9; P = .004), CT acetabular version (β = -0.45; 95% CI, -0.71 to -0.22; P = .001), and LCEA (β = 0.33; 95% CI, 0.19 to 0.47; P = .001) were useful to predict TAC. Multiple linear regression model 2 revealed that AWI (β = 25; 95% CI, 15.67 to 34.4; P = .001), CT acetabular version (β = -0.48; 95% CI, -0.67 to -0.29; P = .001), CT pelvic tilt (β = 0.26; 95% CI, 0.12 to 0.4; P = .001), and LCEA (β = 0.21; 95% CI, 0.1 to 0.3; P = .001) accurately predicted eAASA. Model-based estimates and 95% CIs using 2000 bootstrap samples from the original data were 6.16 to 28.6 for AWI in model 1 and 15.1 to 34.26 for AWI in model 2.

CONCLUSION

There was a moderate to strong correlation between AWI and both TAC and eAASA, whereas ACEA correlated weakly with the former measurements, thus not being useful to quantify anterior acetabular coverage. Other variables such as LCEA, acetabular version, and pelvic tilt may also help predict anterior coverage in asymptomatic hips.

Can a Computational Model Predict the Effect of Lesion Location on Cam-type Hip Impingement?

BACKGROUND

The Warwick consensus defined femoroacetabular impingement syndrome as a motion-related clinical disorder of the hip with a triad of symptoms, clinical signs, and imaging findings representing symptomatic premature contact between the proximal femur and acetabulum. Several factors appear to cause labral and cartilage damage, including joint shape and orientation and patient activities. There is a lack of tools to predict impingement patterns in a patient across activities. Current computational modeling tools either measure pure ROM of the joint or include complexity that reduces reliability and increases time to achieve a solution.

QUESTIONS/PURPOSES

The purpose of this study was to examine the efficacy of a low computational cost approach to combining cam-type hip shape and multiple hip motions for predicting impingement. Specifically, we sought to determine (1) the potential to distinguish impingement in individual hip shapes by analyzing the difference between a cam lesion at the anterior femoral neck and one located at the superior femoral neck; (2) sensitivity to three aspects of hip alignment, namely femoral neck-shaft angle, femoral version angle, and pelvic tilt; and (3) the difference in impingement measures between the individual activities in our hip motion dataset.

METHODS

A model of the shape and alignment of a cam-type impinging hip was created and used to describe two locations of a cam lesion on the femoral head-neck junction (superior and anterior) based on joint shape information available in prior studies. Sensitivity to hip alignment was assessed by varying three aspects from a baseline (typical alignment described in prior studies), namely, femoral neck-shaft angle, femoral version, and pelvic tilt. Hip movements were selected from an existing database of 18 volunteers performing 13 activities (10 male, eight female; mean age 44 ± 19 years). A subset was selected to maximize variation in the range of joint angles and maintain a consistent number of people performing each activity, which resulted in nine people per activity, including at least three of each sex. Activities included pivoting during walking, squatting, and golf swing. All selected hip motion cases were applied to each hip shape model. For the first part of the study, the number of motion cases in which impingement was predicted was recorded. Quantitative analyses of the depth of penetration of the cam lesion into the acetabular socket and qualitative observations of impingement location were made for each lesion location (anterior and superior). In the second part of the study, in which we aimed to test the sensitivity of the findings to hip joint orientation, full analysis of both cam lesion locations was repeated for three modified joint orientations. Finally, the results from the first part of the analysis were divided by activity to understand how the composition of the activity dataset affected the results.

RESULTS

The two locations of cam lesion generated impingement in a different percentage of motion cases (anterior cam: 56% of motion cases; superior cam: 13% of motion cases) and different areas of impingement in the acetabulum, but there were qualitatively similar penetration depths (anterior cam: 6.8° ± 5.4°; superior cam: 7.9° ± 5.8°). The most substantial effects of changing the joint orientation were a lower femoral version angle for the anterior cam, which increased the percentage of motion cases generating impingement to 67%, and lower neck-shaft angle for the superior cam, which increased the percentage of motion cases generating impingement to 37%. Flexion-dominated activities (for example, squatting) only generated impingement with the anterior cam. The superior cam generated impingement during activities with high internal-external rotation of the joint (for example, the golf swing).

CONCLUSION

This work demonstrated the capability of a simple, rapid computational tool to assess impingement of a specific cam-type hip shape (under 5 minutes for more than 100 motion cases). To our knowledge, this study is the first to do so for a large set of motion cases representing a range of activities affecting the hip, and could be used in planning surgical bone removal.

CLINICAL RELEVANCE

The results of this study imply that patients with femoroacetabular impingement syndrome with cam lesions on the superior femoral head-neck junction may experience impinging during motions that are not strongly represented by current physical diagnostic tests. The use of this tool for surgical planning will require streamlined patient-specific hip shape extraction from imaging, model sensitivity testing, evaluation of the hip activity database, and validation of impingement predictions at an individual patient level.

Patient characteristics cannot predict the long-term effect of an intra-articular bupivacaine and corticosteroid injection in patients with femoroacetabular impingement: A retrospective cohort study

Background

To evaluate predictors for effect of an intra-articular (IA) bupivacaine and corticosteroid injection in patients with femoroacetabular impingement syndrome (FAIS).

Methods

All patients between 18 and 50 years old with FAIS who received an intra-articular (IA) bupivacaine and corticosteroid injection between 2016 and 2019 were eligible for this retrospective study. Two groups were made, the non-arthroscopy group (patients for whom conservative treatment with physiotherapy and an IA bupivacaine and corticosteroid injection was sufficient) and the arthroscopy group (patients who needed an arthroscopy because conservative treatment and an IA bupivacaine and corticosteroid injection failed). Multiple regression analysis was performed to analyse the effect of the IA corticosteroid injection and to predict arthroscopic intervention based on sex, age, body mass index, duration of complaints, alpha angle and abnormal bone morphology.

Results

In total 103 patients were included; 46 in the arthroscopy group and 57 in the non-arthroscopy group. The groups had similar baseline characteristics. A total of 37 (36%) patients had an effect of 3 months or longer from the IA corticosteroid injection; 31 (54%) were patients in the non-arthroscopy group versus 6 (13%) patients in the arthroscopy group (P < 0.001). Male sex seems to have an negative influence on the duration of the effect of the injection. None of the variables could significantly predict if a patient would undergo arthroscopic intervention (F(7,103) = 8.54, p = 0.3, R2 = 0.11). The effect of the IA injection could not be predicted (p = 0.1; R2 = 0.13).

Conclusion

There are no patient characteristics that predict who would and who would not benefit from the IA bupivacaine and corticosteroid injection in patients with FAIS and who would need an arthroscopic intervention within 1 year after the injection. Only male sex seems to have an negative influence on the duration of the effect of the injection.

Does the dGEMRIC Index Recover 3 Years After Surgical FAI Correction and an Initial dGEMRIC Decrease at 1-Year Follow-up? A Controlled Prospective Study

BACKGROUND

Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) allows objective and noninvasive assessment of cartilage quality. An interim analysis 1 year after correction of femoroacetabular impingement (FAI) previously showed that the dGEMRIC index decreased despite good clinical outcome.

PURPOSE

To evaluate dGEMRIC indices longitudinally in patients who underwent FAI correction and in a control group undergoing nonoperative treatment for FAI.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

This prospective, comparative longitudinal study included 39 patients (40 hips) who received either operative (n = 20 hips) or nonoperative (n = 20 hips) treatment. Baseline demographic characteristics and presence of osseous deformities did not differ between groups. All patients received indirect magnetic resonance arthrography at 3 time points (baseline, 1 and 3 years of follow-up). The 3-dimensional cartilage models were created using a custom-developed deep learning-based software. The dGEMRIC indices were determined separately for acetabular and femoral cartilage. A mixed-effects model was used for statistical analysis in repeated measures.

RESULTS

The operative group showed an initial (preoperative to 1-year follow-up) decrease of dGEMRIC indices: acetabular from 512 ± 174 to 392 ± 123 ms and femoral from 530 ± 173 to 411 ± 117 ms (both P < .001). From 1-year to 3-year follow-up, dGEMRIC indices improved again: acetabular from 392 ± 123 to 456 ± 163 ms and femoral from 411 ± 117 to 477 ± 169 ms (both P < .001). The nonoperative group showed no significant changes in dGEMRIC indices in acetabular and femoral cartilage from baseline to either follow-up point (all P > .05).

CONCLUSION

This study showed that 3 years after FAI correction, the dGEMRIC indices improved compared with short-term 1-year follow-up. This may be due to normalized joint biomechanics or regressive postoperative activation of the inflammatory cascade after intra-articular surgery.

[Minced cartilage procedure for the treatment of acetabular cartilage lesions of the hip joint]

OBJECTIVE

Treatment of acetabular cartilage defects using autologous cartilage fragments.

INDICATIONS

Acetabular cartilage damage (1-6 cm2) associated with femoroacetabular impingement syndrome (FAIS).

CONTRAINDICATIONS

Advanced osteoarthritis (≥ 2 according to Tönnis) and extensive acetabular cartilage damage > 6 cm2. Lack of labral containment due to irreparable labral damage.

SURGICAL TECHNIQUE

Arthroscopic preparation of the acetabular cartilage damage and removal of unstable cartilage fragments using a 4.0 mm shaver, which minces the cartilage fragments. If necessary, additional cartilage harvesting over the CAM morphology requiring resection. Collection of the cartilage fragments using GraftnetTM and augmentation with autologous conditioned plasma (ACP). Treatment of associated pathologies such as CAM morphology, pincer morphology, and labral refixation or reconstruction. Implantation of cartilage mass and remodeling into the defect zone. Final sealing with autologous fibrin.

POSTOPERATIVE MANAGEMENT

Postoperatively, weight bearing is restricted to 20 kg and range of motion to 90° of flexion for 6 weeks. This is supplemented by passive movement using a continuous passive motion (CPM) device.

RESULTS

Since 2021, 13 patients treated with the described method were followed up for at least 6 months. A significant increase in the International Hip Outcome Tool (iHot)-12 and a significant reduction of pain were observed. No severe complications occurred.

The Effect of a Formal Nonoperative Management Program Combining a Hip Injection With Structured Adjunctive Exercise Rehabilitation in Patients With Symptomatic Femoroacetabular Impingement Syndrome

BACKGROUND

Although the initial treatment recommendations for femoroacetabular impingement syndrome (FAIS) may include nonsurgical therapies such as injections and rehabilitation, many patients undergo isolated injections or a rudimentary exercise regimen.

PURPOSE

To investigate the benefit of an intra-articular hip injection and concomitant structured exercise rehabilitation program in patients with symptomatic FAIS ≥6 months.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

For this study we recruited 49 patients with a mean age of 32.8 years (range, 16-56 years) and symptoms ≥6 months (range, 6-250 months) associated with FAIS, as confirmed via magnetic resonance imaging and radiography. After a guided intra-articular injection of corticosteroid and local anesthetic, patients underwent a structured 12-week rehabilitation program. Patients were assessed before and after injection (8 weeks and 4, 6, 12, and 24 months) with a range of patient-reported outcome measures (PROMs), including the 33-item International Hip Outcome Tool, Hip Outcome Score, modified Harris Hip Score, the Tegner Activity Score, a visual analog scale assessing the frequency and severity of hip pain, and a Global Rating of Change scale. Range of motion, peak isometric hip strength, and hop tests were assessed. Absolute scores and limb symmetry indices were calculated. The percentage of patients transitioning toward surgery over the period was evaluated.

RESULTS

Of the 44 patients who underwent the injection and completed the initial 8-week rehabilitation component, 14 (31.8%) progressed toward surgical intervention over the 24-month postinjection period owing to dissatisfaction and/or symptom recurrence. Patients who progressed toward surgery, as compared with those who did not, reported significantly worse (P < .05) PROMs presurgery and more pain within the first 4 weeks after injection. In the nonoperative cohort, a significant improvement (P < .05) in all PROMs was observed, with 93% of these patients satisfied overall. The Global Rating of Change did not improve, although this was measured only after the injection, reflecting no further significant perceived global change from 8 weeks to 24 months. A significant increase (P < .05) in all hip range of motion and most isometric strength measures was observed at 8 weeks after injection, with these improvements largely sustained until 24 months. Bilateral improvements in hop capacity were observed, with hop test LSIs significantly improving for the single (p = 0.009), triple (p = 0.029) and triple crossover (p = 0.005) hop tests for distance.

CONCLUSION

Although 32% of patients progressed toward surgery, significant improvement in hip pain, symptoms, and physical function was observed in the majority of patients with symptomatic FAIS as a result of a targeted nonoperative management pathway consisting of an intra-articular injection and a structured exercise program.

Evaluating the Need for Preoperative MRI Before Primary Hip Arthroscopy in Patients 40 Years and Younger With Femoroacetabular Impingement Syndrome: A Multicenter Comparative Analysis

Background

Routine hip magnetic resonance imaging (MRI) before arthroscopy for patients with femoroacetabular impingement syndrome (FAIS) offers questionable clinical benefit, delays surgery, and wastes resources.

Purpose

To assess the clinical utility of preoperative hip MRI for patients aged ≤40 years who were undergoing primary hip arthroscopy and who had a history, physical examination findings, and radiographs concordant with FAIS.

Study Design

Cohort study; Level of evidence, 3.

Methods

Included were 1391 patients (mean age, 25.8 years; 63% female; mean body mass index, 25.6) who underwent hip arthroscopy between August 2015 and December 2021 by 1 of 4 fellowship-trained hip surgeons from 4 referral centers. Inclusion criteria were FAIS, primary surgery, and age ≤40 years. Exclusion criteria were MRI contraindication, reattempt of nonoperative management, and concomitant periacetabular osteotomy. Patients were stratified into those who were evaluated with preoperative MRI versus those without MRI. Those without MRI received an MRI before surgery without deviation from the established surgical plan. All preoperative MRI scans were compared with the office evaluation and intraoperative findings to assess agreement. Time from office to arthroscopy and/or MRI was recorded. MRI costs were calculated.

Results

Of the study patients, 322 were not evaluated with MRI and 1069 were. MRI did not alter surgical or interoperative plans. Both groups had MRI findings demonstrating anterosuperior labral tears treated intraoperatively (99.8% repair, 0.2% debridement, and 0% reconstruction). Compared with patients who were evaluated with MRI and waited 63.0 ± 34.6 days, patients who were not evaluated with MRI underwent surgery 6.5 ± 18.7 days after preoperative MRI. MRI delayed surgery by 24.0 ± 5.3 days and cost a mean $2262 per patient.

Conclusion

Preoperative MRI did not alter indications for primary hip arthroscopy in patients aged ≤40 years with a history, physical examination findings, and radiographs concordant with FAIS. Rather, MRI delayed surgery and wasted resources. Routine hip MRI acquisition for the younger population with primary FAIS with a typical presentation should be challenged.

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.

A Deep Learning Algorithm for Radiographic Measurements of the Hip in Adults-A Reliability and Agreement Study

Hip dysplasia (HD) is a frequent cause of hip pain in skeletally mature patients and may lead to osteoarthritis (OA). An accurate and early diagnosis may postpone, reduce or even prevent the onset of OA and ultimately hip arthroplasty at a young age. The overall aim of this study was to assess the reliability of an algorithm, designed to read pelvic anterior-posterior (AP) radiographs and to estimate the agreement between the algorithm and human readers for measuring (i) lateral center edge angle of Wiberg (LCEA) and (ii) Acetabular index angle (AIA). The algorithm was based on deep-learning models developed using a modified U-net architecture and ResNet 34. The newly developed algorithm was found to be highly reliable when identifying the anatomical landmarks used for measuring LCEA and AIA in pelvic radiographs, thus offering highly consistent measurement outputs. The study showed that manual identification of the same landmarks made by five specialist readers were subject to variance and the level of agreement between the algorithm and human readers was consequently poor with mean measured differences from 0.37 to 9.56° for right LCEA measurements. The algorithm displayed the highest agreement with the senior orthopedic surgeon. With further development, the algorithm may be a good alternative to humans when screening for HD.

Quantification of femoral position on radiographic acetabular coverage in children

An accurate assessment of the radiographic acetabular coverage is essential for clinical diagnosis or surgical decision-making in hip disorders. This study aimed to evaluate the effect of femoral position on acetabular coverage and to predict the actual acetabular coverage from nonstandard radiographs. A total of 21 children (34 hips) with normative acetabular coverage were screened in this retrospective study. The Mimics-based local-rotation fluoroscopy simulation method was used to tilt, incline, and rotate the femur in 4° increments within the range of femoral motion. The acetabular coverage, namely acetabular-head index (AHI) and center-edge angle (CEA), increased with femoral abduction but decreased with other motions. Compared to the femoral neutral position, no significant differences were identified in AHI with the rotation (range: 0°-16°) and in CEA with the tilt (range: -20°-4°), inclination (range: 0°-4°), or rotation (range: -8°-40°). The linear regression analysis showed that the CEA increased by about 0.20° for each 1° increase in femoral inclination and decreased by about 0.01°, 0.07°, 0.06°, or 0.07° for each 1° increase in internal rotation, external rotation, flexion, or extension, respectively. And a more significant change in AHI was observed. All femoral malpositions, especially the inclination, affected radiographic acetabular coverage in children. Therefore, each pelvic radiograph should assess potential femoral malpositioning before diagnosing hip disorders. This study will assist surgeons in predicting the acetabular coverage on nonstandard radiographs.

Coxa valga and antetorta increases differences among different femoral version measurements

Aims

To evaluate how abnormal proximal femoral anatomy affects different femoral version measurements in young patients with hip pain.

Methods

First, femoral version was measured in 50 hips of symptomatic consecutively selected patients with hip pain (mean age 20 years (SD 6), 60% (n = 25) females) on preoperative CT scans using different measurement methods: Lee et al, Reikerås et al, Tomczak et al, and Murphy et al. Neck-shaft angle (NSA) and α angle were measured on coronal and radial CT images. Second, CT scans from three patients with femoral retroversion, normal femoral version, and anteversion were used to create 3D femur models, which were manipulated to generate models with different NSAs and different cam lesions, resulting in eight models per patient. Femoral version measurements were repeated on manipulated femora.

Results

Comparing the different measurement methods for femoral version resulted in a maximum mean difference of 18° (95% CI 16 to 20) between the most proximal (Lee et al) and most distal (Murphy et al) methods. Higher differences in proximal and distal femoral version measurement techniques were seen in femora with greater femoral version (r > 0.46; p < 0.001) and greater NSA (r > 0.37; p = 0.008) between all measurement methods. In the parametric 3D manipulation analysis, differences in femoral version increased 11° and 9° in patients with high and normal femoral version, respectively, with increasing NSA (110° to 150°).

Conclusion

Measurement of femoral version angles differ depending on the method used to almost 20°, which is in the range of the aimed surgical correction in derotational femoral osteotomy and thus can be considered clinically relevant. Differences between proximal and distal measurement methods further increase by increasing femoral version and NSA. Measurement methods that take the entire proximal femur into account by using distal landmarks may produce more sensitive measurements of these differences.

Cite this article: Bone Jt Open 2022;3(10):759–766.

A systematic approach to CT evaluation of non-arthritic hip pain

Bone morphology has been increasingly recognized as a significant variable in the evaluation of non-arthritic hip pain in young adults.

Increased availability and use of multidetector CT in this patient population has contributed to better characterization of the osseous structures compared to traditional radiographs.

Femoral and acetabular version, sites of impingement, acetabular coverage, femoral head–neck morphology, and other structural abnormalities are increasingly identified with the use of CT scan.

In this review, a standard CT imaging technique and protocol is discussed, along with a systematic approach for evaluating pelvic CT imaging in patients with non-arthritic hip pain.

An Updated Review of Femoroacetabular Impingement Syndrome

Femoroacetabular impingement (FAI) is a chronic hip condition caused by femoral head and acetabular malformations resulting in abnormal contact across the joint. FAI often leads to labral, cartilaginous, and tissue damage that predispose this patient population to early osteoarthritis (OA). There are a variety of factors that increase the risk for FAI including younger age, Caucasian background, familial FAIS morphology, and competing in high-intensity sports during adolescence. Slow-onset, persistent groin pain is the most frequent initial presenting symptom. On physical examination, patients will typically have a positive FADIR test (flexion, adduction, internal rotation), also known as a positive impingement sign. FAI syndrome can be organized into three classifications; cam, pincer, or mixed. This classification refers to the characteristic morphological changes of the bony structures. The primary imaging modality for diagnosing FAI is a plain radiograph of the pelvis, which can be used to measure the alpha angle and the lateral center edge angle used to quantify severity. Conservative treatment is typically considered first-line treatment for mild to moderate FAI syndrome; however, the outcomes following postoperative surgical intervention have demonstrated excellent results. The most common surgical treatment option for FAI is done arthroscopically.

Male Gender and Competitive Athlete Status Are Associated With Better Outcomes Following Hip Arthroscopy In Patients With Global Acetabular Retroversion

Purpose

To evaluate outcomes of hip arthroscopy in patients with global acetabular retroversion and to identify correlations between sex, radiographic measurements, athlete status, and return to play with patient-reported outcomes (PROs).

Methods

Retrospective study of patients with global acetabular retroversion who underwent arthroscopic femoroacetabular impingement (FAI) surgery was performed. Global acetabular retroversion was defined by 3 criteria: the crossover sign, ischial spine sign, and posterior wall sign on an anteroposterior (AP) pelvic radiograph. Radiographs were used to measure lateral center edge angle, alpha angle, and anterior and posterior wall indices. Femoral version was measured with 3-dimensional computed tomography. Demographics included age, gender, athlete status, return to play, and reoperation. PROs included modified Harris Hip Score, Hip Outcome Score (HOS), Hip Disability and Osteoarthritis Outcome Score, visual analog scale (VAS), and Veterans RAND-12. Spearman correlation determined correlation with perioperative PROs. Generalized estimating equation determined independent predictors. Significance was set at P = .05.

Results

From 2013 to 2019, 149 patients (65.0% female) with 160 hips with FAI and global acetabular retroversion underwent hip arthroscopy. Follow-up averaged 29.6 months. All PROs demonstrated significant improvement with the exception of the Veterans RAND-12 Mental. Female patients scored significantly lower on most postoperative PROs and had greater VAS scores (P = .0002-0.0402). A greater proportion of male subjects met the minimum clinically important difference for the modified Harris Hip Score (88.00% vs 78.79%) Low femoral version correlated with greater HOS ADL, HOS Sport, and Hip Disability and Osteoarthritis Outcome Score Sport scores (P = .0077-0.0177). Athletes reported lower preoperative VAS scores, and higher perioperative scores in multiple PROs (P = .0004-0.0486). Nine hips (5.63%) underwent reoperation.

Conclusions

Patients with global acetabular retroversion and FAI undergoing hip arthroscopy report good outcomes at short-term follow-up. Male subjects and athletes had superior outcomes compared to female subjects and nonathletes. Radiographic measurements did not correlate with outcomes with exception of low femoral version. Athletes reported lower preoperative pain scores and greater postoperative PROs than nonathletes.

Level of Evidence

Level IV, therapeutic case series.

Zero Echo Time Musculoskeletal MRI: Technique, Optimization, Applications, and Pitfalls

Zero echo time (ZTE) imaging is an MRI technique that produces images similar to those obtained with radiography or CT. In ZTE MRI, the very short T2 signal from the mineralized trabecular bone matrix and especially cortical bone-both of which have a low proton density (PD)-is sampled in a unique sequence setup. Additionally, the PD weighting of the ZTE sequence results in less contrast between soft tissues. Therefore, along with gray-scale inversion from black to white and vice versa, ZTE imaging provides excellent contrast between cortical bone and soft tissues similar to that of radiography and CT. However, despite isotropic or near-isotropic three-dimensional (3D) imaging capabilities of the ZTE sequence, spatial resolution in this technique is still inferior to that of radiography and CT, and 3D volume renderings are currently time-consuming and require postprocessing software that features segmentation and manual contouring. Optimization of ZTE MRI mostly entails adjustments of bandwidth, flip angle, field of view, and image matrix. A wide range of structural abnormalities and disease or healing processes in the musculoskeletal system are well delineated with ZTE MRI, including conditions that involve bone-based morphometric analyses (which aid diagnosis, help prognostication, and guide surgery), impaction, avulsion and stress fractures, loose bodies or erosions in and around joints, soft-tissue calcifications and ossifications, and bone tumors (including treatment response). The pitfalls of ZTE imaging include mimics of foci of calcification or ossification such as intra-articular gas and susceptibility artifacts from surgical materials and hemosiderin deposition, which can be avoided in many instances by cross-referencing images obtained with other MRI sequences. Online supplemental material is available for this article. ^©RSNA, 2022.

Juxtaneural ganglia arising from the hip joint: focus on magnetic resonance imaging findings and clinical manifestations

OBJECTIVE

To present cases of juxtaneural ganglia arising from the hip with a discussion of the magnetic resonance imaging (MRI) findings, presenting symptoms, and possible treatment option.

MATERIALS AND METHODS

Two radiologists performed a consensus review of MRI scans obtained between January 2013 and March 2021 to identify patients with juxtaneural ganglia around the hip. A total of 11 patients with 11 juxtaneural ganglia were identified. Medical records and MRI findings were retrospectively reviewed.

RESULTS

Eight patients had lesions involving the sciatic nerve, and three patients had lesions involving the obturator nerve. Sciatic ganglia arose from a paralabral cyst in the posteroinferior quadrant and continued through a narrow channel running along the posterior acetabulum, showing increased diameter in the sciatic foramen and intrapelvic portion. Obturator ganglia showed a J- or reverse J-shape on the coronal imaging plane and extended from a paralabral cyst in the anteroinferior quadrant via the obturator canal. Nine patients (9/11, 81.8%) had symptoms resembling those of lumbosacral radiculopathy. Four patients underwent arthroscopic surgery, and one patient underwent ultrasound-guided aspiration, all of whom showed partial improvement. Spontaneous decrease in the extent of the ganglion was observed in three patients (3/11, 27.3%).

CONCLUSION

This article describes rare cases of juxtaneural ganglia arising from the hip joint and involving the sciatic and obturator nerves. The lesions share similar MRI findings, and each type of cyst (sciatic or obturator ganglia) involves a specific labral quadrant.

Significant improvement after hip arthroscopy for femoroacetabular impingement in women

PURPOSE

This study was designed to evaluate outcomes in women after hip arthroscopy (HA) for femoroacetabular impingement syndrome (FAIS) and compare these results with men.

METHODS

Retrospective study of a prospective database of patients undergoing hip arthroscopy between 2015 and 2018. Inclusion criteria were patients between 18 and 50 years of age, diagnosis of FAIS, complete clinical patient-reported outcomes (PROs), radiographic measurements, and underwent at least a 2-year HA follow-up. For each woman, two men underwent HA were matched in a 1:2 ratio based on age within 5 years, and date of surgery within 6 months. Diagnostic arthroscopy was performed to evaluate labral and chondral status. Radiographic evaluation, a self-administered Hip Outcome Score (HOS) questionnaire, with activity of daily living (ADL) and sports subscale (SSS), and a self-administered short version of the International Hip Outcome Tool (iHOT-12) were assessed at 6 months, 12 months, and then yearly. Clinical relevance was measured with the minimal clinical important difference (MCID), patient acceptable symptom state (PASS), and substantial clinical benefit (SCB) for HOS-ADL, HOS-SSS, and iHOT-12.

RESULTS

One hundred and eighty-five patients met the inclusion criteria. Fifty-two women were matched with 104 men. Significant differences in terms of demographics, radiographic results, intraoperative findings and arthroscopic procedures were found between women and men. Mean follow-up was 48.4 months in women and 50.2 months in men. Both groups showed significant improvement from preoperative PROs to the latest follow-up. There were no significant differences between groups in preoperative PROs, latest follow-up PROs and PROs improvements. The difference in frequency of patients achieving MCID, PASS, and SCB was only significant greater for iHOT-12 PASS in women compared with men.

CONCLUSION

Significant improvements in PROs in women after HA for FAIS at 4-year follow-up were found. Differences between women and men in PROs and rates of achieving MCID, SCB and PASS were only significant for iHOT-12 PASS.

LEVEL OF EVIDENCE

IV.

[Imaging in joint-preserving hip surgery]

Instabilität und Impingement stellen die Hauptpathomechanismen dar, die bereits bei jungen Patienten durch erhöhten mechanischen Stress zu chondrolabralen Schäden, schmerzhafter Bewegungseinschränkung und frühzeitiger Coxarthrose führen können. Ziele der gelenkerhaltenden Chirurgie an der Hüfte sind die Korrektur der knöchernen Deformitäten und chondrolabraler Schäden sowie die Wiederherstellung der Gelenkfunktion. Voraussetzung dafür ist die Identifikation der ursächlichen Pathologien an der Hüfte, welche zudem in Kombination auftreten können. Die dezidierte Röntgen- und Magnetresonanzbildgebung der knöchernen Morphologie und der degenerativen Gelenkbinnenläsionen liefern einen essenziellen Beitrag für die Behandlungsindikation und die Behandlungsplanung. Der vorliegende Artikel soll einen kurzen Überblick über die Hüftdeformitäten mit deren Prävalenz, Pathomechanismus und indizierter Therapie sowie detaillierte Empfehlungen über die spezifische radiologische Abklärung geben.

High prevalence of hip lesions secondary to arthroscopic over- or undercorrection of femoroacetabular impingement in patients with postoperative pain

Objectives

To compare the prevalence of pre- and postoperative osseous deformities and intra-articular lesions in patients with persistent pain following arthroscopic femoroacetabular impingement (FAI) correction and to identify imaging findings associated with progressive cartilage damage.

Methods

Retrospective study evaluating patients with hip pain following arthroscopic FAI correction between 2010 and 2018. Pre- and postoperative imaging studies were analyzed independently by two blinded readers for osseous deformities (cam-deformity, hip dysplasia, acetabular overcoverage, femoral torsion) and intra-articular lesions (chondro-labral damage, capsular lesions). Prevalence of osseous deformities and intra-articular lesions was compared with paired t-tests/McNemar tests for continuous/dichotomous data. Association between imaging findings and progressive cartilage damage was assessed with logistic regression.

Results

Forty-six patients (mean age 29 ± 10 years; 30 female) were included. Postoperatively, 74% (34/46) of patients had any osseous deformity including 48% (22/46) acetabular and femoral deformities. Ninety-six percent (44/46) had an intra-articular lesion ranging from 20% (9/46) for femoral to 65% (30/46) for acetabular cartilage lesions. Prevalence of hip dysplasia increased (2 to 20%, p = 0.01) from pre- to postoperatively while prevalence of cam-deformity decreased (83 to 28%, p < 0.001).

Progressive cartilage damage was detected in 37% (17/46) of patients and was associated with extensive preoperative cartilage damage > 2 h, i.e., > 60° (OR 7.72; p = 0.02) and an incremental increase in postoperative alpha angles (OR 1.18; p = 0.04).

Conclusion

Prevalence of osseous deformities secondary to over- or undercorrrection was high. Extensive preoperative cartilage damage and higher postoperative alpha angles increase the risk for progressive degeneration.

Key Points

• The majority of patients presented with osseous deformities of the acetabulum or femur (74%) and with intra-articular lesions (96%) on postoperative imaging.

• Prevalence of hip dysplasia increased (2 to 20%, p = 0.01) from pre- to postoperatively while prevalence of a cam deformity decreased (83 to 28%, p < 0.001).

• Progressive cartilage damage was present in 37% of patients and was associated with extensive preoperative cartilage damage > 2 h (OR 7.72; p = 0.02) and with an incremental increase in postoperative alpha angles (OR 1.18; p = 0.04).

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-021-08398-4.

Inter-observer concordance in normal and pathological findings of the hip joint in plain radiographs

Background and aim:

The purpose of the study was to compare the data obtained by two independent observers and statistically analyse the results using Cohen’s K to highlight the concordance or discordance in the diagnosis of normality, pathology and, in particular, the type of femoroacetabular impingement (FAI) on plain films.

Methods:

the study was conducted retrospectively. The only inclusion criterium was the minimum age of 20 years. All patients underwent a radiographic examination of the pelvis in standard anteroposterior projection in orthostasis.

Results:

A hundred patients were evaluated. A good concordance between the two operators in the examination of normal hip joint (k= 0.68 right/ 0,74 left) was found; a similar grade of agreement was found for the analysis of “pincer” type FAI (k = 0.73 right, 0,67 left). The best results in concordance were achieved in the examination of “cam” type FAI (k= 0.82 right, 0,88 left), “mixed” type FAI (k = 0.85 right, 0,86 left), and in findings of “coxa profunda” (k = 0.92 right, 0,88 left).

Conclusion:

We found a good concordance between the two readers; a few cases of disagreement were found in the diagnosis of “pincer” type FAI and absence of disease. This discrepancy may be due to the different weight given by the single observer to the clinical indication that leads the patient to examination, but also by the difficulty of a not dedicated radiologist to show some subtle signs indicative of early FAI.

There is no definite consensus on the adequate radiographic correction in arthroscopic osteochondroplasty for femoroacetabular impingement: a systematic review and meta-analysis

PURPOSE

The purpose of this study is to evaluate and define what is considered an adequate radiographic correction in arthroscopic osteochondroplasty for FAI and to secondarily assess how radiographic outcomes relate to patient reported outcomes and complications.

METHODS

The databases EMBASE, PubMed, and MEDLINE were searched for relevant literature from database inception until January 2021. Studies were screened by two reviewers independently and in duplicate for studies reporting on post-operative radiographic outcomes in arthroscopic osteochondroplasty for FAI. Data on radiographic outcomes as well as data reporting functional outcomes and complications were recorded. A meta-analysis was used to combine the mean pre- and post-operative radiographic outcomes using a random effects model. A risk of bias assessment was performed for all included studies using the MINORS score.

RESULTS

The most commonly reported radiographic outcome was the alpha angle with a pooled mean post-operative angle of 44° (95% CI 41°-46°), and mean pre- to post-surgical difference of - 19° (- 22 to - 16, I² = 96%), followed by the LCEA with a pooled mean post-operative angle of 30° (95% CI 29-31) and mean difference after surgery of - 4° (- 6 to - 1, I² = 97%,). Eleven studies reported on the correlation between radiographic and clinical outcomes with no consistent consensus correlation found amongst the included studies. Similarly, six studies correlated radiographic outcomes with conversion to THA with no consistent consensus correlation found amongst the included studies.

CONCLUSION

Based on this review, the main conclusion is that there is no consensus definition on the optimal radiographic correction for FAI and there was no consistent correlation between radiographic correction and functional outcomes. However, based on the uniform improvement in functional outcomes, this review suggests a post-operative alpha angle target of 44° with a correction target of 19° and LCEA target of 30° with a correction target of 3°.

LEVEL OF EVIDENCE

IV.

Benefits of a Specific and Supervised Rehabilitation Program in Femoroacetabular Impingement Patients Undergoing Hip Arthroscopy: A Randomized Control Trial

(1) To assess the efficacy of a specific rehabilitation protocol for femoroacetabular impingement syndrome (FAIS), patients who underwent hip arthroscopy (HA) were compared with a control group. (2) Patients with symptomatic FAIS who were scheduled for HA were randomized either to a control group (n = 45, 66.6% men, 41.8 ± 12.4 years) following a general post-surgical treatment protocol or to an experimental group (n = 45, 71.2% men, 40.9 ± 7.6 years) following a specific rehabilitation protocol supervised by a physiotherapist. Range of motion (ROM), orthopedic tests and pain were assessed immediately before surgery and at 4 and 14 weeks after surgery. The hip functional status was assessed by the modified Harris Hip Score (mHHS) before surgery and at the end of follow-up. (3) At 14 weeks after surgery and compared with the control group, the experimental group showed a lower percentage of positives for hip provocation tests (15.6% vs. 46.6% on Faber test; 15.6% vs. 77.8% on Fadir test; 2.2% vs. 20% on Ober test, experimental vs. control group, p < 0.001), a greater improvement in mHHS (27.2 vs. 10.7 points, p < 0.001) and higher ROM for all the movements evaluated: flexion (99.6 ± 12.2 vs. 89.6 ± 4.5, p < 0.001), extension (20.6 ± 5.8 vs. 13.3 ± 2.6, p < 0.001), adduction (30.6 ± 5.7 vs. 23.4 ± 8.4, p < 0.001), abduction (43.4 ± 10.7 vs. 32.8 ± 8.4, p < 0.001) and both internal (28.2 ± 8.5 vs. 18.7 ± 6.1, p < 0.001) and external hip rotation (36.8 ± 9.3 vs. 27.4 ± 5.6. p < 0.001). The pain decreased after surgery for both groups, although the reduction was greater in the experimental group at the end of intervention (13.8 ± 16.1 vs. 34.9 ± 16.3 mm, experimental vs. control group, p < 0.001). (4) The specific and supervised rehabilitation program in patients with FAIS undergoing HA showed better benefits at 14 weeks of treatment than the benefits achieved by a care protocol in terms of pain reduction and recovery of hip motion.

A three-dimensional measurement method on MR arthrography of the hip to classify femoro-acetabular impingement

PURPOSE

(1) To investigate correlations between different types of FAI and the ratio of acetabular volume (AV) to femoral head volume (FV) on MR arthrography. (2) To assess 2D/3D measurements in identifying different types of FAI by means of cut-off values of AV/FV ratio (AFR).

MATERIALS AND METHODS

Alpha angle, cranial acetabular version, acetabular depth, lateral center edge angle, AV, and FV of 52 hip MR arthrography were measured. ANOVA test correlated different types of FAI with AFR. ROC curves classified FAI by cut-off values of AFR. Accuracy of 2D/3D measurements was calculated.

RESULTS

ANOVA test showed a significant difference of AFR (p value < 0.001) among the three types of FAI. The mean values of AFR were 0.64, 0.74, and 0.89 in cam, mixed, and pincer types, respectively. Cut-off values of AFR were 0.70 to distinguish cam types from mixed and pincer types, and 0.79 to distinguish pincer types from cam and mixed types. Cut-off values identified 100%, 73.9%, and 55.6% of pincer, cam, and mixed types. 2D and 3D classifications of FAI showed accuracy of 40.4% and 73.0%.

CONCLUSIONS

3D measurements were clearly more accurate than 2D measurements. Distinct cut-off values of AFR discriminated cam types from pincer types and identified pincer types in all cases. Cam and mixed types were not accurately recognized.