Hip MRI: Prevalence of articular cartilage defects and labral tears in asymptomatic volunteers. A comparison with a matched population of patients with femoroacetabular impingement

Femoroacetabular impingement syndrome in middle-aged individuals is strongly associated with the development of hip osteoarthritis within 10-year follow-up: a prospective cohort study (CHECK)

OBJECTIVE

The objective is to determine the association and absolute risk of femoroacetabular impingement syndrome (FAIS) for the development of radiographic hip osteoarthritis (RHOA).

METHODS

This is a nationwide, multicentre prospective cohort study (Cohort Hip and Cohort Knee) with 1002 individuals aged between 45 and 65 years. Hips without definitive RHOA (Kellgren-Lawrence (KL) grade≤1) at baseline and with anteroposterior pelvic radiographs at baseline and 10-year follow-up available (n=1386 hips) were included. FAIS was defined by the baseline presence of a painful hip, limited internal hip rotation≤25° and cam morphology defined by an alpha angle>60°. The outcomes were incident RHOA (KL grade≥2 or total hip replacement (THR)) and incident end-stage RHOA (KL≥3 or THR) within 10 years.

RESULTS

Of the 1386 included hips (80% women; mean age 55.7±5.2 years), 21 hips fulfilled criteria for FAIS and 563 hips did not fulfil any of the FAIS criteria (reference group; no symptoms, no signs, no cam morphology). Within 10-year follow-up, 221 hips (38%) developed incident RHOA and 15 hips (3%) developed end-stage RHOA (including 9 hips with THR). Adjusted for sex, age and body mass index, FAIS with cam morphology resulted in an OR of 6.85 (95% CI 2.10 to 22.35) for incident RHOA and 47.82 (95% CI 12.51 to 182.76) for incident end-stage RHOA, compared with hips not having any FAIS criteria. The absolute risk of FAIS was 81% for incident RHOA and 33% for incident end-stage RHOA.

CONCLUSION

FAIS was strongly associated with the development of RHOA within 10 years. Although the baseline prevalence of FAIS was low, the high absolute risk of FAIS for RHOA warrants further studies to determine preventive strategies.

Diagnostic Capability of Intra-Articular Injections for Femoroacetabular Impingement Syndrome: A Systematic Review

OBJECTIVE

To review and critically appraise available literature concerning the diagnostic capability of intra-articular injections for femoroacetabular impingement (FAI) syndrome.

DESIGN

Systematic review.

SETTING

N/A.

PARTICIPANTS

N/A.

INTERVENTIONS

N/A.

MAIN OUTCOME MEASURES

Studies assessing pain relief following intra-articular injections for the diagnosis of FAI syndrome, compared with arthroscopy as diagnostic reference standard, were considered eligible. Searches were performed across 8 databases, and the risk of bias was evaluated through the Quality Assessment of Diagnostic Accuracy Studies tool.

RESULTS

From 489 articles identified, 4 were included for analysis. Intra-articular injections were composed of anesthetic agents (such as lidocaine, bupivacaine, and ropivacaine), combined or not with corticosteroids (triamcinolone and betamethasone). All studies were judged as "at risk of bias", and a substantial heterogeneity was found considering assessment methods and pain relief thresholds for a positive response to intra-articular injections. Overall, 2 studies reported that intra-articular injections presented a high accuracy in determining the presence of FAI syndrome. However, the remaining 2 studies indicated that intra-articular injections might present restricted diagnostic capability to discriminate FAI syndrome from healthy individuals or those with other hip pathologies.

CONCLUSIONS

Based on limited evidence, the diagnostic capability of intra-articular injections for FAI syndrome cannot be supported. It remains unclear which pain relief thresholds are related to a higher diagnostic capability. The combination of anesthetics with corticosteroids should also be further explored, including multiple pain assessments for evaluation of prolonged effects.

Editorial Commentary: Standardized Evaluation of Cartilage Damage and Restoration in Hip Arthroscopy Requires Consideration of Clinical, Imaging, and Patient-Reported Outcomes

Articular cartilage lesions of the acetabulum may result in significant pain and dysfunction for patients with treatment options consisting of either microfracture or various forms of cartilage restoration procedures. A systematic review of 529 patients demonstrated similar, if not lower, reoperation rates and patient-reported outcomes in patients receiving cartilage restoration procedures compared with microfracture. The primary outcomes examined in this review were reoperation rates and patient-reported outcomes with no clear mention of radiographic outcomes and no clearly defined indications as to who would benefit from a cartilage-based procedure. This raises the question as to whether there should be a consensus-based and standardized criteria established and standardized among the hip preservation expert community to evaluate the success of these cartilage restoration procedures from an imaging standpoint. These criteria can also be incorporated into a composite evaluation that combines clinical, imaging, and patient-reported outcomes to determine optimal patient candidacy for cartilage procedures as well. This would be a very useful steppingstone for much-needed future Level I randomized studies or prospective, registry-based data on this topic.

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.

Anterior Electronic Hip Pain Drawings Are Helpful for Diagnosis of Intra-articular Sources of Pain: Lateral or Posterior Drawings Are Unreliable

Purpose

The purpose of this study was to determine the accuracy of electronic hip pain drawing to diagnose intra-articular source of pain in nonarthritic hips, defined by response to an intra-articular injection.

Methods

A retrospective assessment was performed in consecutive patients who had an intra-articular injection completed within a 1-year period. Patients were classified as responders or nonresponders to intra-articular hip injection. A positive injection was defined as greater than 50% hip pain relief within 2 hours after injection. Electronic pain drawings collected before injection were then evaluated according to the hip region marked by the patients.

Results

Eighty-three patients were studied after applying inclusion and exclusion criteria. Anterior hip pain on drawing had a sensitivity of 0.69, specificity of 0.68, positive predictive value (PPV) of 0.86, and negative predictive value (NPV) of 0.44 for intraarticular source of pain. Posterior hip pain on drawing had a sensitivity of 0.59, specificity of 0.23, PPV of 0.68, and NPV of 0.17 for intra-articular source of pain. Lateral hip pain on drawing had a sensitivity of 0.62, specificity of 0.50, PPV of 0.78, and NPV of 0.32 for intraarticular source of pain.

Conclusion

Anterior hip pain on electronic drawing has a sensitivity of 0.69 and specificity of 0.68 for intra-articular source of pain in nonarthritic hips. Lateral and posterior hip pain on electronic pain drawings are not reliable to rule out intra-articular hip disease.

Level of Evidence

Level III, case-control study.

Editorial Commentary: Routine Preoperative Magnetic Resonance Imaging for Hip Arthroscopy Is Wasting Health Care Dollars and Delaying Surgical Intervention: Decision Making Should Be at the Discretion of the Health Care Provider Not Mandated by Health Care Insurers

Making an accurate preoperative diagnosis is critical to optimizing outcomes after hip arthroscopy. A detailed history, thorough physical examination, imaging studies, and diagnostic injections must all be considered in the decision-making process. In today's health care climate, it is imperative to obtain essential and indicated preoperative information while being mindful of health care dollars. Magnetic resonance imaging (MRI) of the hip has been shown to be a highly sensitive modality for hip and pelvis disorders. However, it is critical to recognize that acetabular labral tears and other hip pathology are highly prevalent in an asymptomatic young adult population. There are certainly situations when an MRI should be obtained (suspected arthritic symptoms, avascular necrosis, synovial disorders, uncommon osseous tumors); however, these patients generally present with atypical symptoms. In addition, obtaining an MRI can delay surgical intervention, which has been shown to lead to inferior outcomes in prior studies. MRI is not imperative when patients present with typical intermittent, deep anterior, lateral, groin pain with prolonged sitting, twisting and pivoting, and transitioning from sitting to standing. The typical physical examination includes positive hip impingement testing (FADIR / anterior impingement test) that recreates the patients presenting complaints. Appropriate imaging includes plain radiographs revealing adequate acetabular coverage (not significantly dysplastic) or acetabular overcoverage (pincer-type femoracetabular impingement), cam-type femoracetabular impingement, and well-maintained joint space on all views, including a false profile radiograph to further evaluate the anterior joint space. Finally, a diagnostic injection can be invaluable to further confirm the hip joint proper as the source of pain. If all of the above criteria are met, I strongly believe an MRI is unlikely to alter the surgical decision-making process. In the end, the treating clinician should determine when an MRI is necessary based on the presenting symptoms and examination, rather than insurers applying a blanket requirement for preauthorization. This physician autonomy would ultimately lead to more efficient and cost-effective patient care. Medicine is an art, and unjustified handcuffing of the artist without evidence could result in inferior results.

Patterns of labral tears and cartilage injury are different in femoroacetabular impingement and dysplasia

The aim of this study was to assess injury patterns and risk factors of the acetabular labrum and associated cartilage in patients with femoroacetabular impingement (FAI) versus dysplasia. We retrospectively reviewed 137 patients diagnosed with labral tears and FAI or dysplasia (74 or 63 cases, respectively) through an arthroscopic procedure. Labral and concomitant cartilage injuries were evaluated. Demographics and radiological variables [lateral center-edge angle (LCEA), anterior center-edge angle, acetabular index (AI), acetabular version and alpha angle] were evaluated as risk factors for labral and cartilage injuries. Detachment of acetabular cartilage with intact labro-cartilaginous junction was the most common in dysplasia, whereas cartilage delamination from the labro-cartilaginous junction was more common in FAI (P < 0.001). A higher body mass index was significantly associated with delamination injury in FAI (odds ratio 1.226; 95% CI 1.043–1.441; P = 0.013). A significant correlation was evident between detachment injury and a larger AI in dysplasia (odds ratio 1.127; 95% CI 1.000–1.270; P = 0.049). In addition, symptom duration was positively correlated with the extent of labral tearing in FAI (P = 0.013), whereas the smaller LCEA was correlated with the larger extent of labral tearing in dysplasia (P = 0.044). FAI and dysplasia patients exhibited different labral and cartilage injury patterns. Increased body mass index was correlated with delamination injury in FAI, whereas an increased AI was associated with detachment injury in dysplasia. Greater tearing was associated with a longer symptom duration in FAI, and a decreased LCEA was a risk factor for the extent of tearing in dysplasia.

Level of evidence

Level III. Case–control study.

Quantitative and Qualitative Ultrasound Evaluation for the Diagnosis of an Anterosuperior Acetabular Labral Tear

We investigated the diagnostic performance of qualitative and quantitative ultrasound criteria for anterosuperior acetabular labral tears (ALTs). In all, 118 people with ALTs (120 hips; case group) and 31 asymptomatic volunteers (42 hips; control group) at Peking University Third Hospital between August 2018 and November 2019 were consecutively included. The labral cleft, labral heterogeneous echogenicity, labral plump morphology, paralabral cyst and labral focal hyperechoic area were used as the qualitative criteria. The anterosuperior labral cross-section area (CSA) was measured as the quantitative criterion. The diagnostic utility of the quantitative and qualitative criteria were explored with magnetic resonance imaging as the diagnostic gold standard. Labral heterogeneous echogenicity was the most sensitive criterion for diagnosing ALTs (up to 80.00%), and the specificity of diagnosing ALTs with paralabral cysts, labral focal hyperechoic area and subcortical cysts of the femoral head and neck was as high as 90.48%-100%. The labral CSA in the case group was 0.27 cm² (0.21-0.39 cm²), which was significantly larger compared with the control group (0.18 cm² [0.14-0.23 cm²]; p < 0.001). The area under the receiver operating characteristic curve was 0.802 for diagnosing ALTs according to the labral CSA. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of the combined qualitative criteria for diagnosing ALTs were 90.00%, 71.43%, 90.00%, 71.43% and 85.19%, respectively. Labral heterogeneous echogenicity is a sensitive criterion for diagnosing ALTs, and paralabral cysts, labral focal hyperechoic, area and subcortical cysts of the femoral head and neck are specific criteria. The CSA of the anterosuperior acetabular labrum measured by ultrasound can be used as a quantitative criterion to diagnose ALTs. The combination of labral qualitative criteria provides higher sensitivity and accuracy in diagnosing ALTs.

MRI-- and CT--based metrics for the quantification of arthroscopic bone resections in femoroacetabular impingement syndrome

The purpose of this in vitro study was to quantify the bone resected from the proximal femur during hip arthroscopy using metrics generated from magnetic resonance imaging (MRI) and computed tomography (CT) reconstructed three-dimensional (3D) bone models. Seven cadaveric hemi-pelvises underwent both a 1.5 T MRI and CT scan before and following an arthroscopic proximal femoral osteochondroplasty. The images from MRI and CT were segmented to generate 3D proximal femoral surface models. A validated 3D--3D registration method was used to compare surface--to--surface distances between the 3D models before and following surgery. The new metrics of maximum height, mean height, surface area and volume, were computed to quantify bone resected during osteochondroplasty. Stability of the metrics across imaging modalities was established through paired sample t--tests and bivariate correlation. Bivariate correlation analyses indicated strong correlations between all metrics (r = 0.728--0.878) computed from MRI and CT derived models. There were no differences in the MRI- and CT-based metrics used to quantify bone resected during femoral osteochondroplasty. Preoperative- and postoperative MRI and CT derived 3D bone models can be used to quantify bone resected during femoral osteochondroplasty, without significant differences between the imaging modalities.

Understanding hip pathology in ballet dancers

PURPOSE

The literature on hip injuries in ballet dancers was systematically evaluated to answer (1) whether the prevalence of morphological abnormalities and pathology of hip injuries in dancers differs from the general population (2) if there are any specific risk factors which contribute to a higher rate of hip injury and (3) what are the outcomes of primary and secondary intervention strategies.

METHODS

A systematic literature search of Medline, EMBASE and the Cochrane Library was undertaken for all literature relating to hip injuries in ballet dancers using the PRISMA guidelines. Reference lists were also searched for relevant literature. Clinical outcome studies, prospective/retrospective case series published between 1989 and October 2021 were included. Review articles (non-original data), case reports, studies on animals as well as book chapters were excluded.

RESULTS

The search yielded 445 studies, of which 35 were included for final analyses after screening. This included 1655 participants, of which 1131 were females. The analyses revealed that damage at the chondrolabral junction and degenerative disease of the hip may develop at a higher rate in ballet dancers than in the general population (odds ratio > 1 in 15/18 cohorts). The intra-articular lesions were more frequently found in postero-superior region of the hip suggesting an alternative impingement mechanism. Furthermore, numerous risk factors specific for hip injury in ballet were highlighted amidst a wide body of literature which consistently reports risk factors for a more generic 'dancer vulnerability'.

CONCLUSION

Ballet dancers may suffer from both higher rates of chondrolabral damage and degenerative disease in their hips. In contrast to other sports, the intra-articular lesions are more frequently found in postero-superior region of the hip. Future research clarifying the prevalence of osseous abnormalities and prevention strategies in dancers may be pivotal in delaying the development of hip disease in this cohort.

LEVEL OF EVIDENCE

Level IV.

Biological Augments for Acetabular Chondral Defects in Hip Arthroscopy-A Scoping Review of the Current Clinical Evidence

PURPOSE OF REVIEW

A wide array of joint-preserving surgical techniques exists in the management of acetabular chondral defects (ACDs). The purpose of this review is to summarize the clinical outcomes of the recent biologics used to treat ACDs during hip arthroscopy.

RECENT FINDINGS

Increasing evidence is available for different biological solutions used in the hip. Studies have shown promising outcomes with minimal complications when using biologics as augmentation to microfracture (MF), including different scaffolds or stem cells, or to enhance autologous chondrocyte implantation (ACI). However, data so far is scarce, and more trials and longer follow-ups are needed to better delineate the appropriate indications and benefits for each technique. Presently, the level of evidence is low, but in general, biologics appear safe and trend toward beneficial compared to standard surgical techniques. Augmented MF is recommended for small to medium ACDs, and matrix-assisted ACI or three-dimensional ACI is recommended for medium to large defects.

Magnetic Resonance Arthrographic Findings After Hip Labrum Resection Versus Refixation

The aim of this study was to evaluate whether new tissue formation occurs after labral debridement/excision, and, if so, which morphological features are typical for a neo-labrum. The authors further compared the findings after labrum resection with those seen after labrum refixation. Patients with femoroacetabular impingement who underwent hip arthroscopy or surgical hip dislocation to address a labrum pathology were retrospectively included, and postoperative magnetic resonance arthrography studies were assessed. Forty-two patients had undergone either labrum resection (n=25) or refixation (n=17), performed arthroscopically (47.6%) or via surgical hip dislocation (52.4%). In the subgroup of patients after debridement/resection, there was anterosuperior/superior scar tissue in 83.5%, with amorphous configuration in 92%, irregular surface in approximately two-thirds of the cases, and a mean±SD thickness of 7.0±2.7 mm. A labrum-like shape of the scar plate was seen in 7.7%. Regarding the subgroup of patients who had undergone labral refixation, an irregular or rounded labrum shape was noted in 26.5% and 51.3% of cases, respectively, with a triangular shape in less than one-fourth of cases. Labrum re-tears (35.7%) were mainly observed at the base (71.7%), rather than within the labral substance (28.4%). New tissue formation can be observed in the majority of cases after excision of the hip labrum, with amorphous and irregular surface configuration compared with a native labrum. This new tissue should therefore be referred to as scar tissue rather than as neo-labrum. Whether scar tissue is inferior to a refixed labrum needs to be further elucidated in follow-up studies. [Orthopedics. 2021;44(4):e607-e613.].

The correlation between the labrum size and the labral tear in asymptomatic volunteers and symptomatic patients

BACKGROUND

Some studies have proved that labrum size is associated with symptoms in patients with hip labral tear. The correlation between the labrum size and the labral tear in asymptomatic volunteers and symptomatic patients is still uncertain.

METHODS

The volunteers with no history of pain, injury, or surgery were recruited from the community. Patients who were diagnosed with labral tear and underwent hip arthroscopic surgery in this period in our hospital were also included. The length and height of the acetabular hip labrum were measured at three separate anatomic sites through magnetic resonance imaging (MRI) along the acetabular rim: lateral, anterior, and anteroinferior.

RESULTS

A total of 70 volunteers (125 hips) and 70 patients (70 hips) were included in this study. Sixty-six (52.8%) hips had labral tears in all 125 hips of volunteers. The lateral labral length of volunteers with labral tears was significantly larger than those without labral tears (P < .05). In 14 volunteers with unilateral labral tears, length of lateral, anterior, and anteroinferior labrum in the side with tear were significantly larger than normal on the other side. The anterior labral height of volunteers was significantly larger than that of patients (P < .05).

CONCLUSIONS

In conclusion, asymptomatic volunteers with larger length of lateral, anterior, and anteroinferior labrum are more prone to present with labral tears. Symptomatic patients with labral tears exhibited thinner anterior labrum. Further studies are warranted to explore the mechanisms of labral tears in asymptomatic people and validate the use of labral size as a guide to differential diagnosis and treatment.

Consistency of 3D femoral torsion measurement from MRI compared to CT gold standard

Background

Several hip and knee pathologies are associated with aberrant femoral torsion. Diagnostic workup includes computed tomography (CT) and magnetic resonance imaging (MRI). For three-dimensional (3D) analysis of complex deformities it would be desirable to measure femoral torsion from MRI data to avoid ionizing radiation of CT in a young patient population. 3D measurement of femoral torsion from MRI has not yet been compared to measurements from CT images. We hypothesize that agreement will exist between MRI and CT 3D measurements of femoral torsion.

Methods

CT and MRI data from 29 hips of 15 patients with routine diagnostic workup for suspected femoroacetabular impingement (FAI) were used to generate 3D bone models. 3D measurement of femoral torsion was performed by two independent readers using the method of Kim et al. which is validated for CT. Inter-modalitiy and inter-reader intraclass correlation coefficients (ICC) were calculated.

Results

Between MRI and CT 3D measurements an ICC of 0.950 (0.898; 0.976) (reader 1) respectively 0.950 (0.897; 0.976) (Reader 2) was found. The ICC (95% CI) expressing the inter-reader reliability for both modalities was 0.945 (0.886; 0.973) for MRI and 0.957 (0.910; 0.979) for CT, respectively. Mean difference between CT and MRI measurement was 0.42° (MRI – CT, SD: 2.77°, p = 0.253).

Conclusions

There was consistency between 3D measurements of femoral torsion between computer rendered MRI images compared to measurements with the “gold standard” of CT images. ICC for inter-modality and inter-reader consistency indicate excellent reliability. Accurate, reliable and reproducible 3D measurement of femoral torsion is possible from MRI images.

3.0 T MRI findings of 104 hips of asymptomatic adults: from non-runners to ultra-distance runners

Objectives

To determine and compare the health status of hip joints of individuals undertaking various lengths of long-distance running and of those who are not running.

Methods

Fifty-two asymptomatic volunteers underwent bilateral hip 3.0 Tesla MRI: (1) 8 inactive non-runners; (2) 28 moderately active runners (average half a marathon (21 km)/week) and (3) 16 highly active runners (≥ marathon (42 km)/week). Two musculoskeletal radiologists reported the hip MRI findings using validated scoring systems. Study participants completed a Hip disability and Osteoarthritis Outcome Score (HOOS) questionnaire to indicate their perceived hip function.

Results

The MRI findings show that there were no significant differences among inactive non-runners, moderately active runners and highly active runners in the amount of labral abnormalities (p=0.327), articular cartilage lesions (p=0.270), tendon abnormalities (p=0.141), ligament abnormalities (p=0.519). Bone marrow oedema was significantly more common in moderately active runners than in non-runners and highly active runners (p=0.025), while small subchondral cysts were more common in runners than in non-runners (p=0.017), but these were minor/of small size, asymptomatic and did not indicate specific exercise-related strain. Articular cartilage lesions and bone marrow oedema were not found in highly active runners. HOOS scores indicate no hip symptoms or functional problems among the three groups.

Conclusion

The imaging findings were not significantly different among inactive non-runners, moderately active runners and highly active runners, in most hip structures, suggesting that long-distance running may not add further damage to the hip joints.

Influence of simulated hip muscle weakness on hip joint forces during deep squatting

This study aimed to determine the effects of simulated hip muscle weakness on changes in hip joint forces during deep squat motion. Ten healthy individuals performed squat motion at three different positions (0° foot angle [N-squat], 10° toe-in [IN-squat], and 30° toe-out [OUT-squat]). A scaled musculoskeletal model for each participant was used to calculate the muscle and hip joint forces. For each hip muscle, models of full strength, mild muscle weakness (15% decrease), and severe muscle weakness (30% decrease) were created. The muscles affecting the hip joint forces were identified, and the rate of change in the joint forces was compared among the three squat conditions. The anterior hip joint force was increased in the muscle weakness models of the inferior gluteus maximus (iGlutMax) and iGlutMax+deep external rotator (ExtRot) muscles. With 30% muscle weakness of these muscles, statistically significant differences in the rate of increase in the anterior joint force were observed in the following order: IN-squat (iGlutMax, 29.5%; iGlutMax+ExtRot, 41.4%), N-squat (iGlutMax, 18.3%; iGlutMax+ExtRot, 27.8%), and OUT-squat (iGlutMax, 5.6%; iGlutMax+ExtRot, 9.3%). OUT-squat may be recommended to minimize the increase in hip joint forces if accompanied by hip muscle weakness.

Association between severity of hip chondrolabral injuries, dynamic hip muscle strength and quality of life: A cross-sectional study in patients with femoroacetabular impingement syndrome scheduled for hip arthroscopy

BACKGROUND

We assessed the association between: the severity of hip chondral or labral pathology with dynamic hip muscle strength or quality of life in patients with femoroacetabular impingement syndrome scheduled for hip arthroscopy. We also assessed the association between dynamic hip muscle strength with quality of life.

METHODS

Eighty-three participants with femoroacetabular impingement syndrome scheduled for hip arthroscopy were included. We measured dynamic hip abduction and adduction muscle strength with an isokinetic dynamometer (Nm/kg), and quality of life with the iHoT-33 questionnaire. The severity of hip chondrolabral pathologies was scored using the modified Beck classification. Linear regression analyses were conducted to assess the association between severity of hip chondral or labral pathology with dynamic hip muscle strength and quality of life.

FINDINGS

The regression analyses showed no association between the (i) severity of hip chondral (adjusted r²: 0.14) or labral (adjusted r²: 0.08) pathology and quality of life (P > 0.05), (ii) between the severity of hip chondral or labral pathology and dynamic hip abduction and adduction muscle strength (P > 0.05). Significant correlation was observed for quality of life and hip abduction (adjusted r²:0.29; P < 0.001) or adduction (adjusted r²: 0.32; P < 0.001) muscle strength.

INTERPRETATION

The severity of hip chondral or labral pathologies were not associated with quality of life or dynamic hip muscle strength in participants with femoroacetabular impingement syndrome. Greater dynamic hip abduction and adduction muscle strength were associated with better quality of life in participants with femoroacetabular impingement syndrome scheduled for hip arthroscopy.

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

OBJECTIVES

Imaging diagnosis of femoroacetabular impingement (FAI) remains controversial due to a lack of high-level evidence, leading to significant variability in patient management. Optimizing protocols and technical details is essential in FAI imaging, although challenging in clinical practice. The purpose of this agreement is to establish expert-based statements on FAI imaging, using formal consensus techniques driven by relevant literature review. Recommendations on the selection and use of imaging techniques for FAI assessment, as well as guidance on relevant radiographic and MRI classifications, are provided.

METHODS

The Delphi method was used to assess agreement and derive consensus among 30 panel members (musculoskeletal radiologists and orthopedic surgeons). Forty-four questions were agreed on and classified into five major topics and recent relevant literature was circulated, in order to produce answering statements. The level of evidence was assessed for all statements and panel members scored their level of agreement with each statement during 4 Delphi rounds. Either "group consensus," "group agreement," or "no agreement" was achieved.

RESULTS

Forty-seven statements were generated and group consensus was reached for 45. Twenty-two statements pertaining to "Imaging techniques" were generated. Eight statements on "Radiographic assessment" and 12 statements on "MRI evaluation" gained consensus. No agreement was reached for the 2 "Ultrasound" related statements.

CONCLUSION

The first international consensus on FAI imaging was developed. Researchers and clinicians working with FAI and hip-related pain may use these recommendations to guide, develop, and implement comprehensive, evidence-based imaging protocols and classifications.

KEY POINTS

• Radiographic evaluation is recommended for the initial assessment of FAI, while MRI with a dedicated protocol is the gold standard imaging technique for the comprehensive evaluation of this condition. • The MRI protocol for FAI evaluation should include unilateral small FOV with radial imaging, femoral torsion assessment, and a fluid sensitive sequence covering the whole pelvis. • The definite role of other imaging methods in FAI, such as ultrasound or CT, is still not well defined.

Osseous defect of the anteroinferior femoral head: is it associated with femoroacetabular impingement (FAI)?

OBJECTIVE

To evaluate the prevalence, morphology, and clinical significance of a repeatedly observed yet not examined circumscript osseous defect at the anteroinferior aspect of the femoral head, termed femoral head defect.

MATERIALS AND METHODS

Retrospective study with approval of the institutional review board. There was informed consent by all individuals. Magnetic resonance imaging (MRI) hip examinations of 970 individuals (age 15 to 55) were analyzed for femoral head defect. Patients with femoral head defect were matched for age and gender with patients without defect. Two readers independently assessed MRI images regarding presence, location, and morphology of the defect. MR images and radiographs were analyzed for findings of femoroacetabular impingement (FAI). Femoral torsion was measured. Independent t test and chi-square test were used for statistics.

RESULTS

Sixty-eight (7%) of 970 MRI examinations exhibited a femoral head defect in an anteroinferior location of the femoral head (29/400 men, 7.3%; 39/570 women, 6.8%; p = 0.8). The most frequent morphology of femoral head defect was type I, dent-like (34; 50%), followed by type II, crater-like (27; 40%), and III, cystic (7; 10%). Femoral head defect was slightly more common on the right hip (39 individuals; 57%) compared to left (29 individuals; 43%), non-significantly (p = 0.115). There was no association between FAI or its subtypes and the presence of femoral head defect (p = 0.890). Femoral antetorsion was reduced in patients with femoral head defect (12.9° ± 8.6) compared to patients without defect (15.2° ± 8.5), without statistical significance (p = 0.121).

CONCLUSION

The femoral head defect is a common finding in MRI examinations of the hip and is situated in the anteroinferior location. There was no association with FAI yet a non-significant trend towards lower femoral antetorsion in patients with femoral head defects.

Mid-term results after in situ pinning and hip arthroscopy for mild slipped capital femoral epiphysis: a minimum five-year follow-up

PURPOSE

In situ pinning of mild slipped capital femoral epiphysis (SCFE) results in an aspherical head-neck junction and arthroscopic osteochondroplasty can successfully correct the head-neck junction. However, whether the correction stays stable over at least five years remains unknown.

METHODS

In a retrospective and consecutive series, 11 patients with a mean age of 12 years (range, 10 years to 15 years) were included. All patients were treated for mild SCFE with in situ pinning and staged hip arthroscopy correcting the head-neck junction. All patients were assessed clinically and radiographically (radiograph and magnetic resonance imaging (MRI)) pre-operatively, 12 weeks and at least five years' post-operatively.

RESULTS

The mean range of motion (ROM) for flexion and internal rotation was stable over time with 100° (sd 4) and 21° (sd 6), respectively at the last follow-up. The mean alpha angle decreased from pre-operative 64° (range 61° to 68°) to 12 weeks post-operative 49° (range 46° to 52°; p = 0.001) and stayed stable over time. New superficial cartilage damage on either the acetabular or femoral side was seen in each three patients. Progressive labral degeneration was present in two patients.

CONCLUSION

In situ pinning and staged hip arthroscopy for the correction of mild SCFE is safe, restores normal alpha angles and reveals stable morphological correction at mid-term follow-up. Furthermore, the clinical results were excellent with almost normalized internal hip rotation at mid-term follow-up in patients who had reached adulthood. However, there was some joint deterioration, but without negative impact on subjective and clinical outcome after at least five years.

LEVEL OF EVIDENCE

IV.

1.5 T magnetic resonance imaging generates accurate 3D proximal femoral models: Surgical planning implications for femoroacetabular impingement

The objective of this study was to validate three-dimensional (3D) proximal femoral surface models generated from a 1.5 T magnetic resonance imaging (MRI) by comparing these 3D models to those derived from the clinical "gold standard" of computed tomography (CT) scan and to ground-truth surface models obtained by laser scans (LSs) of the excised femurs. Four intact bilateral cadaveric pelvis specimens underwent CT and MRI scans and 3D surface models were generated. Six femurs were extracted from these specimens, and the overlying soft tissues were removed. The extracted femurs were then laser scanned to produce a ground-truth surface model. A 3D-3D registration method was used to compare the signed and absolute surface-to-surface distances between the 3D models. Absolute agreement was evaluated using a 95% confidence interval (CI) derived from the precision of the LS ground-truth. Paired samples t tests and Kolmogrov-Smirnov tests were performed to compare the differences between the signed and absolute surface-to-surface distances between the models. The average signed surface-to-surface distances for the MRI vs LS and MRI vs CT models were 0.07 and 0.16 mm, respectively. These differences fell within the 95% CI of ±0.20 mm indicating absolute agreement between the surface models generated from these modalities. The signed surface-to-surface distance was significantly smaller for MRI vs LS ground truth model as compared with the CT vs LS model. Femoral models derived from a 1.5 T MRI scan demonstrated absolute agreement with the clinical gold standard of CT-derived models and were most like LS ground truth models of the excised femurs.

Prediction of intra-articular pathology and arthroscopic outcomes for femoroacetabular impingement and labral tear based on the response to preoperative anaesthetic hip joint injections

OBJECTIVE

This study investigated whether the preoperative response to intra-articular injections is associated with intra-articular pathological findings and arthroscopy outcomes.

METHODS

This study included 49 patients who underwent arthroscopic hip surgery for femoroacetabular impingement and labral tear after receiving preoperative hip joint injections. The response to anaesthetic injections was categorized as poor (0-50%) or good (51-100%). With respect to anatomical indices, we evaluated the lateral centre-edge angle (LCEA), acetabular roof obliquity (ARO), vertical-centre-anterior angle (VCA), and the alpha angle (on a lateral view). We evaluated the association between these indices (including the types of hip labral tears and cartilage damage) and the effectiveness of intra-articular injections.

RESULTS

The study included 22 men and 27 women, and the mean age of patients was 36.4 years. No statistically significant association was observed between the response to preoperative anaesthetic hip joint injections and patient demographics (age, sex) and anatomical indices (LCEA, ARO, VCA, and alpha angle) (p > 0.05). All patients showed labral damage; however, labral tear classification or cartilage damage was not significantly associated with the effectiveness of joint injections. At the 1-year post-operative follow-up, patients with a good response to anaesthetic hip joint injections showed a significantly better outcome than patients with a poor response to these injections (p < 0.01).

CONCLUSION

The response to preoperative anaesthetic hip joint injections may indicate the presence of intra-articular pathology. Furthermore, this association may have predictive value in determining post-operative outcomes following hip arthroscopy.

Glossary of terms for musculoskeletal radiology

Members of the International Skeletal Society compiled a glossary of terms for musculoskeletal radiology. The authors also represent national radiology or pathology societies in Asia, Australia, Europe, and the USA. We provide brief descriptions of musculoskeletal structures, disease processes, and syndromes and address their imaging features. Given the abundance of musculoskeletal disorders and derangements, we chose to omit most terms relating to neoplasm, spine, intervention, and pediatrics. Consensus agreement was obtained from 19 musculoskeletal radiology societies worldwide.

Contributions of the Capsule and Labrum to Hip Mechanics in the Context of Hip Microinstability

Background

Hip microinstability and labral pathology are commonly treated conditions with increasing research emphasis. To date, there is limited understanding of the biomechanical effects of the hip capsule and labrum on controlling femoral head motion.

Purpose/Hypothesis

The purpose of this study was to determine the relative role of anterior capsular laxity and labral insufficiency in atraumatic hip microinstability. Our hypotheses were that (1) labral tears in a capsular intact state will have a minimal effect on femoral head motion and (2) the capsule and labrum work synergistically in controlling hip stability.

Study Design

Controlled laboratory study.

Methods

Twelve paired hip specimens from 6 cadaveric pelvises (age, 18-41 years) met the inclusion criteria. Specimens were stripped of all soft tissue except the hip capsule and labrum, then aligned, cut, and potted using a custom jig. A materials testing system was used to cyclically stretch the anterior hip capsule in extension and external rotation, while rotating about the mechanical axis of the hip. Labral insufficiency was created with a combined radial and chondrolabral tear under direct visualization. A motion tracking system was used to record hip internal-external rotation and displacement of the femoral head relative to the acetabulum in the anterior-posterior, medial-lateral, and superior-inferior directions. Testing variables included baseline, postventing, postcapsular stretching, and postlabral insufficiency.

Results

When comparing the vented state with each experimental pathologic state, increases in femoral head motion were noted in both the capsular laxity state and the labral insufficiency state. The combined labral insufficiency and capsular laxity state produced statistically significant increases (P < .001) in femoral head translation compared with the vented state in all planes of motion.

Conclusion

Both the anterior capsule and labrum play a role in hip stability. In this study, the anterior hip capsule was the primary stabilizer to femoral head translation, but labral tears in the setting of capsular laxity produced the most significant increases in femoral head translation.

Clinical Relevance

This study provides a physiologic biomechanical assessment of the hip constraints in the setting of hip microinstability. It also sheds light on the importance of the hip capsule in the management of labral tears. Our study demonstrates that labral tears in isolation provide minimal changes in femoral head translation, but in the setting of a deficient capsule, significant increases in femoral head translation are seen, which may result in joint-related symptoms.

Magnetic Resonance Arthrography, a valuable pre-operative imaging modality in femoro-acetabular impingement

Background

The diagnostic accuracy of MR arthrography in preoperative assessment of labral tears and chondral abnormalities in femoroacetabular impingement patients.

A non-randomized control study including 31 FAI patients (17 male and 14 females, mean age 31.9 years). All patients underwent MR arthrography after US-guided intra-articular contrast injection. Conventional and MR arthrography images were evaluated for bone abnormalities (including alpha angle and acetabular depth measurements), labral tears, and chondral abnormalities. The results were correlated to arthroscopy as the gold standard. Sensitivity, specificity, PPV, and NPV in the detection of labral tears and chondral abnormalities were statistically calculated.

Results

The included FAI patients presented cam (mean age 30.4 years ± 6.8 years), pincer (mean age 33.6 years ± 9.8 years), and mixed (mean age 36.6 years ± 12.9 years) types with the predominance of cam type. Cam type predominated in the male, while pincer and mixed types predominated in female patients. MR arthrography detected 41 labral tears in 23 patients with 87.5%, 71.4%, 91.3%, and 62.5% sensitivity, specificity, PPV, and NPV, respectively, and detected chondral abnormalities in 13 patients with 66.7%, 92.3%, 92.3%, and 66.7% sensitivity, specificity, PPV, and NPV, respectively.

Conclusion

MR arthrography is a valuable imaging modality in preoperative assessment of FAI patients. Besides identifying the type of impingement through alpha angle and acetabular depth measurements, it detects labral tears with high sensitivity and PPV. Although less sensitive in detection of chondral abnormalities, our results showed high specificity.

Editorial Commentary: Consider the Sacroiliac Joint: Imaging a Source of Pain Can Feel Compelling. Orthopaedists Would Do Well to Remain Skeptical

With regard to the association of sacroiliac (SI) pain and hip arthroscopy outcomes, it is vital to understand that imaging the SI joint may be unreliable. A recent systematic review on diagnostic accuracy for SI joint pain concluded that more reliable criteria are strongly positive responses to diagnostic injection and a physical examination in which 3 or more provocative maneuvers are positive. SI joint degenerative changes can be found in a majority of asymptotic patients and might be considered normal finding until proven otherwise. When it comes to the spine and pelvis, radiologic changes should be interpreted by caution by both hip surgeons and spine surgeons.

The Diagnostic Value of Ultrasound in Anterosuperior Acetabular Labral Tear

PURPOSE

To investigate diagnostic value of ultrasound in acetabular labral tears compared with magnetic resonance (MR) imaging, using arthroscopic surgery as the gold standard in a relatively large sample size.

METHODS

We retrospectively evaluated patients who attended the sports medicine clinic of our department and underwent arthroscopic surgery for the diagnosis of an anterosuperior acetabular labral tear between June 2014 and April 2018. All the patients received hip joint ultrasound examination and MR imaging evaluation before arthroscopic surgery. The sensitivity, specificity, and accuracy of ultrasound and MR imaging were calculated and compared.

RESULTS

A total of 195 patients were enrolled in this study. Of these, 184 had arthroscopically confirmed anterosuperior acetabular labral tear. The sensitivity, specificity, positive predictive value (PPV), negative predictive value, and accuracy by ultrasound were, respectively, 68.5%, 81.8%, 98 4%, 13.4%, and 69.2%, retrospectively. For MR imaging, the sensitivity, specificity, PPV, negative predictive value, and accuracy were 84.8%, 63.6%, 97.5%, 20.0%, and 83.6%, respectively.

CONCLUSIONS

Although ultrasound had a slightly lower sensitivity for detecting anterosuperior acetabular labral tear, it had a higher specificity and PPV than MR imaging. With the advantages of being inexpensive, relatively quick, noninvasive, and having dynamic evaluation, ultrasound could be used as a feasible method to evaluate anterosuperior acetabular labral tear.

LEVEL OF EVIDENCE

Level IV, case series.

Acetabular Labral Tears Are Common in Asymptomatic Contralateral Hips With Femoroacetabular Impingement

BACKGROUND

The number of patients undergoing hip arthroscopy for labral tears has increased, but labral tears are sometimes seen in asymptomatic patients with femoroacetabular impingement (FAI). The frequency of this finding, however, has not been well characterized nor is the proportion of patients with previously asymptomatic labral tears who may later become symptomatic.

QUESTIONS/PURPOSES

The purpose of this study was to determine (1) the prevalence of labral tears and other intraarticular pathology in the asymptomatic contralateral hip of patients undergoing surgery for symptomatic FAI; (2) the likelihood that the asymptomatic hip had become symptomatic at latest followup; and (3) any association between MRI findings and age, sex, and body mass index (BMI) in both symptomatic and asymptomatic sides.

METHODS

This study included patients who were diagnosed with unilateral symptomatic FAI between 2013 and 2015 and who had an available MRI of both hips. The study included 100 patients (47 females, 53 males) with a mean age of 33 years (range, 17-57 years). Patients with a symptomatic contralateral hip (n = 56) or an unsuitable MRI for review based on both reviewers' consensus (n = 344) were excluded. The MRI of both hips was independently evaluated by two orthopaedic surgeons and interobserver reliability tested. The interobserver reliability for the two surgeons' MRI ratings was almost perfect (κ ≥ 0.85). The presence of a labral tear, an acetabular chondral lesion, subchondral acetabular cysts, and fibrocystic changes in the femoral head-neck junction was documented for both hips. At latest followup, asymptomatic hips were investigated for any symptomatic labral tears or surgical procedures resulting from FAI.

RESULTS

A labral tear was recorded in 97 (97%) and 96 (96%) of symptomatic hips, respectively, for each surgeon's evaluation. A labral tear was also detected in 41 (41%) and 43 (43%) of asymptomatic hips. In addition, an acetabular chondral lesion was detected in 32 (32%) and 35 (35%) of the symptomatic hips and 15 (15%) and 17 (17%) of the asymptomatic hips. At latest followup, nine of the patients were diagnosed with symptomatic labral tears in the contralateral asymptomatic hip and were treated. None of the radiologic parameters examined demonstrated an association with patient age, sex, or BMI in either symptomatic or asymptomatic hips.

CONCLUSIONS

Labral tears and acetabular chondral lesions are common in the asymptomatic contralateral hip of patients undergoing surgery for FAI. The incidence of a symptomatic labral tear in these asymptomatic hips was 9% during 2 years of followup. We suggest that the decision to perform chondral or labral surgery in patients with FAI should be made with caution considering the relatively high prevalence of labral tears in asymptomatic hips and the low chance of development of symptoms.

LEVEL OF EVIDENCE

Level IV, case-series study.

The Role of Anterior Capsular Laxity in Hip Microinstability: A Novel Biomechanical Model

BACKGROUND

Hip microinstability is an increasingly recognized source of hip pain and disability. Although the clinical entity has been well described, the pathomechanics of this disease remain poorly understood.

PURPOSE/HYPOTHESIS

The purpose of this study was to determine the role of capsular laxity in atraumatic hip microinstability. Our hypothesis was that cyclic stretching of the anterior hip capsule would result in increased hip range of motion and femoral head displacement.

STUDY DESIGN

Controlled laboratory study.

METHODS

In this study, 7 hip specimens met inclusion criteria (age, 18-46 years). Specimens were stripped of all soft tissue, aligned, cut, and potted by use of a custom jig. A materials testing system was used to cyclically stretch the anterior hip capsule in extension and external rotation while rotating about the mechanical axis of the hip. A motion tracking system was used to record hip rotation and displacement of the femoral head relative to the acetabulum in the anterior-posterior, medial-lateral, and superior-inferior directions. Testing was conducted at baseline, after venting, and after capsular stretching.

RESULTS

With the hip in anatomic neutral alignment, cyclic stretching of the anterior hip capsule resulted in increased hip rotation ( P < .001). Femoral head displacement significantly increased relative to the vented state in the medial-lateral ( P < .001), anterior-posterior ( P = .013), and superior-inferior ( P = .036) planes after cyclic stretching of the anterior hip capsule.

CONCLUSION

The anterior hip capsule plays an important role in controlling hip rotation and femoral head displacement. This study is the first to display significant increases in femoral head displacement through a controlled cyclic stretching protocol of the anterior hip capsule.

CLINICAL RELEVANCE

This study is directly applicable to the treatment of atraumatic hip microinstability. The results quantitatively define the relative importance of the hip capsule in controlling femoral head motion. This allows for a better understanding of the pathophysiological process of hip microinstability and serves as a platform to develop effective surgical techniques for treatment of this disease.

Risk Factors for Bilateral Femoroacetabular Impingement Syndrome Requiring Surgery

Purpose:

To identify the risk factors for contralateral surgery in patients undergoing hip arthroscopy for femoroacetabular impingement syndrome (FAIS).

Methods:

Patients who underwent unilateral surgery were compared with those who underwent staged bilateral surgery to identify risk factors associated with bilateral surgery. Variables examined included demographics, comorbidities, and radiographic features. Binary logistic regression was used to identify predictors of bilateral FAIS.

Results:

A total of 694 patients with an average age of 34.0 ± 13.1 years met were included in the analysis. Overall, 109 patients (15.3%) had staged bilateral hip arthroscopy for FAIS. Risk factors associated for bilateral FAIS requiring surgery were decreased age and lower Charlson Comorbidity Index (CCI). Compared with patients aged <25 years, those aged 25 to 34 years (odds ratio [OR], 0.5; P = 0.031), 35 to 44 years (OR, 0.5; P = 0.034), and ≥45 years (OR, 0.3; P = 0.002) had lower odds of bilateral labral tear. In addition, patients with a CCI <2 were three times more likely to require bilateral FAIS surgery (OR, 3.4; P = 0.044). None of the radiographic parameters predicted bilateral labral tears.

Conclusion:

Patients younger than 25 years and those with a CCI <2 had markedly increased rates of bilateral FAIS necessitating surgery compared with older patients. This study may be of value in preoperative counseling.

Pincer-type MRI morphology seen in over a third of asymptomatic healthy volunteers without femoroacetabular impingement

BACKGROUND

In daily routine, pincer femoroacetabular impingement (FAI) findings are often seen without a clinical diagnosis of pincer FAI.

PURPOSE

To assess the presence of pincer FAI MRI findings in asymptomatic volunteers with negative impingement test versus patients with clinically confirmed FAI.

STUDY TYPE

Case-control study.

POPULATION

Sixty-three asymptomatic volunteers and 63 matched patients with FAI were included.

FIELD STRENGTH/ SEQUENCE

A coronal T₁ -weighted turbo spin-echo sequence as well as a 3D oblique transverse water-excitation true fast imaging sequence at 1.5T.

ASSESSMENT

The volunteers underwent standard MRI of the hip, and patients underwent MR arthrography of the symptomatic hip using the same MR sequences. Measurements of cranial acetabular version, acetabular depth, and lateral center-edge angle were performed independently by three fellowship-trained musculoskeletal radiologists.

STATISTICAL TESTS

Descriptive statistics, Mann-Whitney U-test, Unpaired t-test, receiver operating characteristics (ROC), Intraclass correlation coefficient (ICC).

RESULTS

Forty-one percent (26/63, reader 1), 32% and 37% (20 and 23/63, reader 2/3) of asymptomatic volunteers had at least one positive MR finding for pincer-FAI. Patients with pincer or mixed-type FAI had cranial retroversion of the acetabulum of -0.2° ± 7.1 (mean ± standard deviation) for reader 1 and -0.3° ± 5.5/-0.2° ± 4.8 for reader 2 / reader 3, while asymptomatic volunteers had an anteversion of 6.2° ± 6.4 (reader 1) and 3.2° ± 4.9/3.1° ± 6.5 (readers 2/3): This difference was statistically significant (P ≤ 0.002), but there was a large overlap between the groups. Acetabular depth measurements were very similar for patients with either pincer or mixed-type FAI (5.1-5.3 mm ± 3.1) and volunteers (5.2-6.1 mm ± 2.6), without a statistically significant difference (P ≤ 0.50). Lateral center-edge angle was also similar in patients with either pincer or mixed-type FAI (32.1-35.1° ± 9.1) and volunteers (30.7-33.2° ± 6.5), without a statistically significant difference (P ≤ 0.28).

DATA CONCLUSION

There is a large overlap in pincer-type MRI findings between patients with symptomatic FAI and asymptomatic volunteers. More than a third of volunteers exhibited at least one positive pincer-type MRI finding.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1296-1303.

Differences in Hip Joint Biomechanics and Muscle Activation in Individuals With Femoroacetabular Impingement Compared With Healthy, Asymptomatic Individuals: Is Level-Ground Gait Analysis Enough?

Background:

Femoroacetabular impingement (FAI) is a recognized cause of hip and groin pain and a significant factor in hip joint function during sport. Objective tests for understanding hip function are lacking in this population.

Purpose:

To determine whether biomechanical and electromyographic features of hip function during level-ground walking differ between a group diagnosed with FAI and those with no symptoms of FAI.

Study Design:

Controlled laboratory study.

Methods:

A total of 20 asymptomatic individuals and 20 individuals with FAI walked on a dual-belt instrumented treadmill at self-selected walking velocities. Sagittal and frontal plane joint motions, moments, and muscle activation for the gluteus medius, gluteus maximus, rectus femoris, and medial and lateral hamstrings were analyzed. Discrete measures were extracted from each biomechanical waveform, and principal component analysis was used to determine hip joint muscle activation and hip adduction moment patterns. Statistical significance was determined by use of Student t tests with Bonferroni adjustments for multiple comparisons (α = .05).

Results:

Individuals with FAI walked more slowly (P = .015) and had lower self-reported function (P < .001). No differences in muscle strength were found between the symptomatic and contralateral legs in the FAI group (P > .017), but those with FAI had lower strength in the knee extensors and flexors and the hip extensors, flexors, and adductors compared with the asymptomatic group (P < .017). Individuals with unilateral symptomatic FAI walked with similar biomechanical and hip muscle electromyographic results bilaterally. The only differences found were a greater amplitude of gluteus maximus activation in the FAI symptomatic leg compared with the asymptomatic group and greater medial hamstring activation than lateral hamstring activation in the FAI group in both limbs compared with the asymptomatic group.

Conclusion:

Individuals with FAI were generally deconditioned and reported significantly more functional limitations. No biomechanical differences existed between groups during level walking, yet hamstring and gluteus maximus activation differed when the symptomatic group was compared with the asymptomatic group.

Clinical Relevance:

The field lacks objective testing of hip joint function to understand implications of FAI for dynamic movements, particularly with applications to biomechanics and electromyography. Level walking was of limited value for understanding FAI hip function, and the development of a more challenging gait assessment is warranted.

What is the prevalence of imaging-defined intra-articular hip pathologies in people with and without pain? A systematic review and meta-analysis

BACKGROUND

Intra-articular hip pathologies are thought to be associated with the development of hip and groin pain. A better understanding of the relationship between symptoms and imaging findings may improve the management of individuals with intra-articular hip pathologies.

OBJECTIVE

To undertake a systematic review and meta-analysis to determine the prevalence of intra-articular hip pathologies in individuals with and without pain.

METHODS

Seven electronic databases were searched in February 2017 for studies investigating the prevalence of intra-articular hip pathologies using MRI, MRA or CT. Two independent reviewers conducted the search, study selection, quality appraisal and data extraction. Meta-analysis was performed when studies were deemed homogenous, with a strength of evidence assigned to pooled results.

RESULTS

In general, studies were moderate to high risk of bias, with only five studies adjudged to be low risk of bias. The 29 studies reporting on the prevalence of intra-articular hip pathologies identified limited evidence of a labral tear prevalence of 62% (95% CI 47% to 75%) in symptomatic individuals, with moderate evidence identifying a labral tear prevalence of 54% (95% CI 41% to 66%) in asymptomatic individuals. Limited evidence demonstrated a cartilage defect prevalence of 64% (95% CI 25% to 91%) in symptomatic individuals, compared with moderate evidence of a cartilage defect prevalence of 12% (95% CI 7% to 21%) in asymptomatic individuals.

CONCLUSION

The prevalence of intra-articular hip pathologies is highly variable in both symptomatic and asymptomatic populations. The prevalence of intra-articular hip pathologies appears to be higher in symptomatic individuals. However, imaging-defined intra-articular hip pathologies are also frequently seen in asymptomatic individuals, highlighting a potential discordant relationship between imaging pathology and pain.

PROSPERO REGISTRATION NUMBER

CRD42016035444.

Imaging evaluation of the hip after arthroscopic surgery for femoroacetabular impingement

Arthroscopic surgery for femoroacetabular impingement (FAI) is increasingly frequently performed. Initial reports were that complications were very low, but as experience has increased, a number of long-term complications, in addition to factors related to poor clinical outcomes, have been identified. This review describes the normal and abnormal postoperative imaging appearance of the hip after arthroscopy for FAI. Abnormalities discussed include incomplete resection or over-resection of the impingement lesion, heterotopic ossification, cartilage damage, chondrolysis, instability and dislocation, recurrent labral tear, adhesions, psoas atrophy, infection, and avascular necrosis.