UTE T2* cartilage mapping in the hip: a pilot study assessing cartilage in patients with femoroacetabular impingement

BACKGROUND

UTE T2* cartilage mapping use in patients undergoing femoroacetabular impingement (FAI) has been lacking but may allow the detection of early cartilage damage.

PURPOSE

To assess the reproducibility of UTE T2* cartilage mapping and determine the difference in UTE T2* values between FAI and asymptomatic patients and to evaluate the correlation between UTE T2* values and patient-reported symptoms.

MATERIAL AND METHODS

Prospective evaluation of both hips (7 FAI and 7 asymptomatic patients). Bilateral hip 3-T MRI scans with UTE T2* cartilage maps were acquired. A second MRI scan was acquired 1-9 months later. Cartilage was segmented into anterosuperior, superior, and posterosuperior regions. Assessment was made of UTE T2* reproducibility (ICC). Mean UTE T2* values in patients were compared (t-tests) and correlation was made with patient-reported outcomes (Spearman's).

RESULTS

ICCs of mean UTE T2* were as follows: acetabular, 0.82 (95% CI=0.50-0.95); femoral, 0.76 (95% CI=0.35-0.92). Significant strong correlation was found between mean acetabular UTE T2* values and iHOT12 (ρ = -0.63) and moderate correlation with mHHS (ρ = -0.57). There was no difference in mean UTE T2* values between affected vs. non-affected FAI hips. FAI-affected hips had significantly higher values in acetabulum vs. asymptomatic patients (13.47 vs. 12.55 ms). There was no difference in mean femoral cartilage values between the FAI-affected hips vs. asymptomatic patients. The posterosuperior femoral region had a higher mean value in non-affected FAI hips vs. asymptomatic patients (12.60 vs. 11.53 ms).

CONCLUSION

UTE T2* cartilage mapping had excellent reproducibility. Affected FAI hips had higher mean acetabular UTE T2* values than asymptomatic patients. Severity of patient-reported symptoms correlates with UTE T2* acetabular cartilage values.

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.

Effects of the location of both anterior and lateral boundaries of the necrotic lesion on collapse progression in osteonecrosis of the femoral head

BACKGROUND

The location of the lateral boundary of the necrotic lesion to the weight-bearing portion of the acetabulum (Type classification) is an important factor for collapse in osteonecrosis of the femoral head (ONFH). Recent studies also reported the significance of the location of the anterior boundary of the necrotic lesion on the occurrence of collapse. We aimed to assess the effects of the location of both anterior and lateral boundaries of the necrotic lesion on collapse progression in ONFH.

METHODS

We recruited 55 hips with post-collapse ONFH from 48 consecutive patients, who were conservatively followed for more than one year. Using a plain lateral radiograph (Sugioka's lateral view), the location of the anterior boundary of the necrotic lesion to the weight-bearing portion of the acetabulum was classified as follows: Anterior-area I (two hips) occupying the medial one-third or less; Anterior-area II (17 hips) occupying the medial two-thirds or less; and Anterior-area III (36 hips) occupying greater than the medial two-thirds. The amount of femoral head collapse was measured by biplane radiographs at the onset of hip pain and each follow-up period, and Kaplan-Meier survival curves with collapse progression (≥1 mm) as the endpoint were produced. The probability of collapse progression was also assessed by the combination of Anterior-area and Type classifications.

RESULTS

Collapse progression was observed in 38 of the 55 hips (69.0%). The survival rate of hips with Anterior-area III/Type C2 was significantly lower. Among hips with Type B/C1, collapse progression occurred more frequently in hips with Anterior-area III (21 of 24 hips) than in hips with Anterior-area I/II (3 of 17 hips, P < 0.0001).

CONCLUSIONS

Adding the location of the anterior boundary of the necrotic lesion to Type classification was useful to predict collapse progression especially in hips with Type B/C1.

Hip Disorders in Bull Riders: Clinical Observations and Outcomes of Arthroscopy

Bull riders represent a microcosm of athletes in whom severe consequences of femoroacetabular impingement may challenge the limits of arthroscopic intervention. Observations of this cohort may provide meaningful insight into the treatment of other populations. All patients undergoing hip arthroscopy are prospectively assessed with a modified Harris Hip Score. Sixteen consecutive bull riders (21 hips) with minimum 2-year follow-up are reported. The average age was 26 years, duration of symptoms was 33 months, and follow-up was 57 months. Arc of rotational hip motion averaged 31°. All had femoroacetabular impingement (17 combined and 4 cam impingements). Among the cam impingements, 1 also had dysplasia and 1 also had borderline dysplasia. Radiographic Tönnis grades were as follows: 2 Tönnis 1; 18 Tönnis 2; and 1 Tönnis 3. All had acetabular articular damage (14 Outerbridge grade 4; 6 Outerbridge grade 3; and 1 Outerbridge grade 1). Nine underwent microfracture. Four had accompanying femoral chondral lesions (3 grade 3; 1 grade 4). There were 20 labral tears (14 repaired and 6 debrided). All but 1 (95%) improved after surgery. One bilateral case underwent conversion to resurfacing arthroplasty on one side and revision arthroscopy on the other. The average improvement was 21.3 points. Thirteen (81.25%) returned to bull riding at an average of 7 months. Among the 3 who did not return, each had undergone bilateral procedures. There were no complications. Femoroacetabular impingement can be a significant problem among bull riders. Limited range of motion, grade 4 articular damage, and Tönnis 2 radiographic changes may not preclude successful arthroscopic treatment, but advanced bilateral disease may be too much even for these hardened athletes. [Orthopedics. 2024;47(2):79-82.].

Editorial Commentary: Small Labral Size on Magnetic Resonance Imaging Is an Indication for Labral Reconstruction in the Setting of Revision Hip Arthroscopy

Revision hip arthroscopy is an increasingly common procedure as rates of primary hip arthroscopy rise. Etiologies for symptom recurrence may include residual femoroacetabular impingement, cam over-resection, labral pathology, chondral wear, adhesions, and instability. This has spawned sophisticated surgical techniques in hip arthroscopy including labral reconstruction. Indications for labral reconstruction in the revision setting obviously include labral deficiency. In addition, in the absence of other obvious reasons for failure of the primary procedure, a labral reconstruction should be considered for diminutive labra. The ability to predict labral size before surgery based on magnetic resonance imaging can be invaluable.

Editorial Commentary: Concomitant Hip Arthroscopy and Periacetabular Osteotomy Treat Both the Cause and the Effects of Hip Dysplasia: The Best of Both Worlds

In the management of true hip dysplasia, the bony deformity is nearly always accompanied by, and often causal of, intra-articular pathology. It is strongly recommended to conduct a comprehensive preoperative evaluation as well as arthroscopic evaluation and treatment of coexisting hip joint conditions prior to performing an open Bernese periacetabular osteotomy. The osteotomy improves coverage of the femoral head and corrects the abnormal joint mechanics and loading patterns, which result in cartilage damage and subsequent osteoarthritis. Arthroscopy allows treatment of the intra-articular pathology. Combining the hip arthroscopy and periacetabular osteotomy procedures into a single surgical intervention, performed by either a single surgeon or a collaborative surgical team, allows us to address both the cause and the effects of dysplasia. This once-controversial combined technique has become a standard practice in the field with widespread adoption.

Analysis of cam location characteristics in FAI syndrome patients from 3D MR images demonstrates sex-specific differences

Cam femoroacetabular impingement (FAI) syndrome is associated with hip osteoarthritis (OA) development. Hip shape features, derived from statistical shape modeling (SSM), are predictive for OA incidence, progression, and arthroplasty. Currently, no three-dimensional (3D) SSM studies have investigated whether there are cam shape differences between male and female patients, which may be of potential clinical relevance for FAI syndrome assessments. This study analyzed sex-specific cam location and shape in FAI syndrome patients from clinical magnetic resonance examinations (M:F 56:41, age: 16-63 years) using 3D focused shape modeling-based segmentation (CamMorph) and partial least squares regression to obtain shape features (latent variables [LVs]) of cam morphology. Two-way analysis of variance tests were used to assess cam LV data for sex and cam volume severity differences. There was no significant interaction between sex and cam volume severity for the LV data. A sex main effect was significant for LV 1 (cam size) and LV 2 (cam location) with medium to large effect sizes (p < 0.001, d > 0.75). Mean results revealed males presented with a superior-focused cam, whereas females presented with an anterior-focused cam. When stratified by cam volume, cam morphologies were located superiorly in male and anteriorly in female FAI syndrome patients with negligible, mild, or moderate cam volumes. Both male and female FAI syndrome patients with major cam volumes had a global cam distribution. In conclusion, sex-specific cam location differences are present in FAI syndrome patients with negligible, mild, and moderate cam volumes, whereas major cam volumes were globally distributed in both male and female patients.

Hip Capsulolabral Complex: Anatomy, Disease, MRI Features, and Postoperative Appearance

The hip is a uniquely constrained joint with critical static stability provided by the labrum, capsule and capsular ligaments, and ligamentum teres. The labrum is a fibrocartilaginous structure along the acetabular rim that encircles most of the femoral head. Labral tears are localized based on the clock-face method, which determines the extent of the tear while providing consistent terminology for reporting. Normal labral variants can mimic labral disease and can be differentiated by assessment of thickness or width, shape, borders, location, and associated abnormalities. The Lage and Czerny classification systems are currently the most well-known arthroscopic and imaging systems, respectively. Femoroacetabular impingement is a risk factor for development of labral tears and is classified according to bone dysmorphisms of the femur ("cam") or acetabulum ("pincer") or combinations of both (mixed). The capsule consists of longitudinal fibers reinforced by ligaments (iliofemoral, pubofemoral, ischiofemoral) and circular fibers. Capsular injuries occur secondary to hip dislocation or iatrogenically after capsulotomy. Capsular repair improves hip stability at the expense of capsular overtightening and inadvertent chondral injury. The ligamentum teres is situated between the acetabular notch and the fovea of the femoral head. Initially considered to be inconsequential, recent studies have recognized its role in hip rotational stability. Existing classification systems of ligamentum teres tears account for injury mechanism, arthroscopic findings, and treatment options. Injuries to the labrum, capsule, and ligamentum teres are implicated in symptoms of hip instability. The authors discuss the labrum, capsule, and ligamentum teres, highlighting their anatomy, pathologic conditions, MRI features, and postoperative appearance. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

The correlation between hip alpha angle and acetabular labral tear location and size: A cross-sectional study

BACKGROUND

Explore the correlation between hip morphology and labral tear location/size.

METHODS

This retrospective study analyzed patients with hip pain who received magnetic resonance (MR) arthrography at our institution, between January 2017 and December 2020. Imaging analysis includes labral tear location and size, and hip morphology measurement with alpha angle, lateral center-edge (CE) angle, anterior CE angle, and femoral neck version. The correlation between hip morphology angles and labral tear location/size was evaluated using multiple regression, followed by stratification analysis with Chi-square test to investigate interactions between the variables.

RESULTS

A total of 103 patients (105 hips) with hip pain who received MR arthrography (mean age, 50 years ± 15 [SD]) were included, with mean alpha angle of 57.7° ± 9.9° [SD], mean lateral CE angle of 32.6° ± 6.8° [SD], mean anterior CE angle of 58.2° ± 8.1° [SD], mean femoral neck version of 17.1° ± 8.2° [SD]. Large alpha angle (>57°) and older age were both correlated with superior and posterosuperior labral tear incidence ( p < 0.05) and larger tear size ( p < 0.05). Furthermore, alpha angle is significantly correlated with superior labral tear incidence in young-age subgroup (age <45 years) ( p < 0.05), also significantly correlated with posterosuperior labral tear incidence and larger tear size in middle-age subgroup (45 ≤ age ≤ 60 years) ( p < 0.05).

CONCLUSION

A large alpha angle (>57°) is significantly correlated with increased incidence of superior and posterosuperior labral tear, and larger tear size in patients with hip pain, and the relationships depend on age.

Combined femoral and acetabular version and synovitis are associated with dGEMRIC scores in people with femoroacetabular impingement (FAI) syndrome

This study sought to explore, in people with symptoms, signs and imaging findings of femoroacetabular impingement (FAI syndrome): (1) whether more severe labral damage, synovitis, bone marrow lesions, or subchondral cysts assessed on magnetic resonance imaging (MRI) were associated with poorer cartilage health, and (2) whether abnormal femoral, acetabular, and/or combined femoral and acetabular versions were associated with poorer cartilage health. This cross-sectional study used baseline data from the 50 participants with FAI syndrome in the Australian FASHIoN trial (ACTRN12615001177549) with available dGEMRIC scans. Cartilage health was measured using delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) score sampled at the chondrolabral junction on three midsagittal slices, at one acetabular and one femoral head region of interest on each slice, and MRI features were assessed using the Hip Osteoarthritis MRI Score. Analyses were adjusted for alpha angle and body mass index, which are known to affect dGEMRIC score. Linear regression assessed the relationship with the dGEMRIC score of (i) selected MRI features, and (ii) femoral, acetabular, and combined femoral and acetabular versions. Hips with more severe synovitis had worse dGEMRIC scores (partial η2  = 0.167, p = 0.020), whereas other MRI features were not associated. A lower combined femoral and acetabular version was associated with a better dGEMRIC score (partial η2  = 0.164, p = 0.021), whereas isolated measures of femoral and acetabular version were not associated. In conclusion, worse synovitis was associated with poorer cartilage health, suggesting synovium and cartilage may be linked to the pathogenesis of FAI syndrome. A lower combined femoral and acetabular version appears to be protective of cartilage health at the chondrolabral junction.

Feasibility of feline coxofemoral arthroscopy using a supratrochanteric lateral portal: A cadaveric study

OBJECTIVE

To evaluate the feasibility of feline diagnostic coxofemoral arthroscopy.

STUDY DESIGN

Ex vivo feline cadaveric descriptive study.

ANIMALS

Seven feline cadavers (14 hips).

METHODS

Gross dissection of two feline hips was performed to evaluate anatomic landmarks, guide arthroscopic portal development, and determine optimal limb positioning. A 1.9 mm, 0° arthroscope, inserted through a supratrochanteric lateral portal, was used to assess intraarticular structures in 12 feline cadaver hips. Arthroscopy was followed by gross dissection of periarticular soft tissues. Relative portal locations and damage to periarticular structures were recorded. Hips were disarticulated, and an India ink assay was performed to assess whether there was iatrogenic cartilage injury (ICI).

RESULTS

Scope insertion was achieved in all hips. Articular cartilage of the femoral head and acetabulum, round ligament, joint capsule, transverse acetabular ligament, and dorsal acetabular rim were identified arthroscopically in all hips. Probe insertion and intra-articular structure palpation was achieved in all hips. Scope and instrument portals resulted in minimal periarticular muscle trauma. No sciatic nerve damage was detected. Minor partial thickness ICI was observed in all hips at the site of scope insertion. Focal full thickness ICI was noted in one hip.

CONCLUSION

Arthroscopy of the feline coxofemoral joint allowed visual and probe evaluation of intra-articular structures without evidence of major periarticular neurovascular trauma. Iatrogenic cartilage injury occurred in all hips but severity of lesions was considered mild.

CLINICAL SIGNIFICANCE

Coxofemoral arthroscopy is feasible in cats and can be utilized as a diagnostic tool for minimally invasive joint evaluation.

The correlation between transient osteoporosis of the hip and pregnancy: A review

Transient osteoporosis of the hip is indubitably a comparatively infrequent entity affecting both men and women worldwide. Its occurrence in the course of pregnancy, specifically in the third trimester, and lactation are of paramount concernment. The exact association between transient hip osteoporosis and pregnancy is precarious. Etiology and potential pathophysiological mechanisms behind this correlation are still to be utterly defined. Magnetic resonance imaging is highly regarded as the gold standard imaging method for assiduous assessment of this disorder. Physicians of copious medical specialties should practice scrupulous techniques for early and pertinent diagnosis when pregnant women are presented with persistent hip pain, as differential diagnosis with femoral head avascular necrosis can be exceedingly arduous. Treatment is predominantly conservative with protected weight-bearing and analgesic medication in the first line of management. In terms of prognosis, the disease ordinarily resolves spontaneously after a few months. Further research is required in order to elucidate the ambiguity surrounding the establishment of globally approved diagnosis and treatment guidelines for pregnancy-associated transient hip osteoporosis. This paper aims to accentuate the significance of this particular disorder by providing a succinct review of the existing literature, augmenting clinicians' knowledge about the features of pregnancy-related transient proximal femur osteoporosis.

[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.

Relationship between the Hip Abductor Muscles and Abduction Strength in Patients with Hip Osteoarthritis

This study aimed to determine which muscle the gluteus maximus, gluteus medius, gluteus minimus (Gmin), or tensor fasciae latae (TFL) contributes most to hip abduction strength and to identify effective sites for cross-sectional area (CSA) Gmin and TFL measurement in hip osteoarthritis (OAhip) patients. Twenty-eight patients with OAhip were included. The muscle CSA and volume were determined using magnetic resonance imaging. Peak isometric strength was determined using hand-held dynamometry. Muscle volumes were normalized to the total muscle volume of hip abductors. Multiple regression analysis was performed. The difference between the CSA of Gmin and TFL was calculated, and correlations with volume and muscle strength were determined. Gmin volume was related to abductor muscle strength (p=0.042). The peak CSA of the Gmin correlated with muscle volume and strength. The CSA of the TFL correlated with volume, with no difference between the CSA of the most protruding part of the lesser trochanter and peak CSA. Gmin volume was strongly related to abductor muscle strength. Peak CSA is a useful parameter for assessing the CSA of the Gmin among patients with OAhip. The CSA of the TFL should be measured at the most protruding part of the lesser trochanter.

[Septic arthritis and transient synovitis of the hip]

CLINICAL/METHODICAL ISSUE

Differentiating between septic arthritis and transient synovitis can be challenging but is very important as a late diagnosis of septic arthritis can lead to sepsis and joint damage. For correct diagnosis and prediction of complications, the right combination of physical examination, laboratory and radiological studies is needed.

STANDARD RADIOLOGICAL METHODS

Hip ultrasound is easy to learn and has a high sensitivity for joint effusion. Faster diagnosis and therapy are possible due to increasing use of ultrasound. Magnetic resonance imaging (MRI) is primarily used to rule out co-infections (osteomyelitis, pyomyositis) and differential diagnoses. X‑ray is typically nonremarkable in septic arthritis.

PRACTICAL RECOMMENDATIONS

Routine use of ultrasound in nontraumatic pediatric hip pain. Generous use of MRI in case of elevated inflammatory markers or inconclusive clinical findings. Using only few sequences may be appropriate to avoid sedation, primarily fluid sensitive sequences (fat-saturated T2, TIRM, STIR), in case of positive findings, accompanied by T1-weighted images.

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).

Epigenetic dysregulation of articular cartilage during progression of hip femoroacetabular impingement disease

Femoroacetabular impingement (FAI) is an important trigger of hip osteoarthritis (OA). Epigenetic changes in DNA methyltransferase 3B (DNMT3B) attenuate catabolic gene expression in cartilage hemostasis. This study aimed to examine the articular chondrocyte catabolic state and DNMT3B and 4-aminobutyrate aminotransferase promoter (ABAT) expression during OA progression in FAI. Cartilage samples were collected from the impingement zone of 12 patients with cam FAI (early-FAI) and 12 patients with advanced OA secondary to cam FAI (late-FAI-OA). Five healthy samples were procured from cadavers (ND: nondiseased). Explants were cultured under unstimulated conditions, catabolic stimulus (IL1β), or anabolic stimulus (TGFβ). Histology was performed with safranin-O/fast-green staining. Gene expression was analyzed via qPCR for GAPDH, DNMT3B, ABAT, MMP-13, COL10A1. Methylation specific PCR assessed methylation status at the ABAT promoter. Cartilage samples in early-FAI and late-FAI-OA showed a histological OA phenotype and increased catabolic marker expression (MMP13/COL10A1, ND vs. early-FAI, p = 0.004/p < 0.001, ND vs. late-FAI-OA, p < 0.001/p < 0.001). RT-PCR confirmed DNMT3B underexpression (ND vs. early-FAI, p < 0.001, early-FAI vs. late-FAI-OA, p = 0.016) and ABAT overexpression (ND vs. early-FAI, p < 0.001, early vs. late-FAI-OA, p = 0.035) with advanced disease. End-stage disease showed ABAT promoter hypomethylation. IL1β stimulus accentuated ABAT promoter hypomethylation and led to further ABAT and catabolic marker overexpression in early-FAI and late-FAI-OA while TGFβ normalized these alterations in gene expression. Catabolic and epigenetic molecule expression suggested less catabolism in early-stage disease. Sustained inflammation induced ABAT promoter hypo-methylation causing a catabolic phenotype. Suppression of ABAT by methylation control could be a new target for therapeutic intervention to prevent OA progression in hip FAI.

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.

Magnetic resonance-based hip muscles retrospective analysis shows deconditioning and recovery after total hip arthroplasty surgery

PURPOSE

The purpose of this study is to estimate the effect of unilateral hip osteoarthritis (OA) on hip muscle volume and fatty infiltration and to evaluate changes of muscles after total hip arthroplasty (THA) surgery.

METHODS

A retrospective analysis was conducted on patients with unilateral hip OA subjected to THA with perioperative pelvic girdle 1.5 T magnetic resonance imaging (MRI). Thirty-five patients were included. Ten of these have also postoperative MRIs. Medius gluteus (MG) and iliopsoas (IP) muscles were manually segmented on the MRI scans, the corresponding 3D muscle geometries were reconstructed, and the volumes extracted. Muscle quality was assessed using the Goutallier classification on coronal MRI images. Volume and muscle quality differences were calculated between healthy and affected side.

RESULTS

Pre-operatively, MG and IP on the affected side presented a mean muscle volume 17.5 ± 18% (p < 0.001) and 14.4 ± 15.8% (p < 0.001) smaller than the healthy counterpart, respectively. Muscles on the affected side showed a significant higher grade of fatty infiltration compared to the healthy side (p < 0.05 for MG; p < 0.001 for IP). At an average follow-up of 13 ± 5.3 months after THA, MG, and IP muscles of the affected hip showed an average 22.8% (p < 0.001) and 28.2% (p < 0.001) volume increase after THA. Also, the healthy side showed a significant increase of muscle volume for IP (17.1% p < 0.001). No significant change for MG muscle was observed.

CONCLUSIONS

The study demonstrated preoperative reduced muscle volume and higher fatty infiltration at the muscles of the OA hip compared to the contralateral healthy one. A significant positive effect of THA on hip muscle volume was observed. These findings give an interesting insight on muscle deconditioning and recovery in patients undergoing THA.

The Cartilage Protective Effect of Labrum Reconstruction Using Meniscus Allograft Compared with Labrum Resection in a Porcine Model

PURPOSE

This study aimed to verify the femoral head cartilage protective effect of labral reconstruction in a porcine model.

METHODS

Twelve pigs (24 hips) were divided into 3 groups: labrum defect group, lateral meniscus (LM) allograft group, and LM allograft wrapped with acellular peritoneum matrix (LM-APM) group before undergoing bilateral hip surgery. The pigs were sacrificed at 12 and 24 weeks postoperatively, while the femoral head cartilage was retrieved and then subjected to imaging measurement, macroscopic observations, and biomechanical and histological assessment.

RESULTS

Imaging measurement and macroscopic observations revealed that the defect area of the labrum was filled in LM and LM-APM allograft groups after 24 weeks, whereas the labrum defect remained at 24 weeks in the control group. The femoral head cartilage corresponding to the area of labral resection in the labral defect group had worse macroscopic Osteoarthritis Research Society International (OARSI) scores, uneven and discontinuous cartilage on hematoxylin and eosin (H&E) staining and Safranin O staining, decreased histopathology OARSI Osteoarthritis Cartilage Histopathology Assessment System (OOCHAS) scores, and decreased elastic modulus and hardness at 12 and 24 weeks after surgery compared with the meniscus allograft groups.

CONCLUSION

This study demonstrated that the LM allograft with or without APM for labral reconstruction had a chondroprotective effect on the femoral head in a porcine model.

Acetabular cartilage delamination: performance of MRI using arthroscopy as the standard of reference

BACKGROUND

Femoroacetabular impingement (FAI) frequently leads to acetabular chondral delamination. Early identification and treatment of these cases is crucial to prevent further damage to the hip.

PURPOSE

To evaluate the accuracy of morphological signs of cartilage acetabular delamination in non-arthrographic magnetic resonance imaging (MRI) using intra-articular arthroscopic findings in patients undergoing FAI surgery.

MATERIAL AND METHODS

All hip MRI scans were assessed individually by three independent radiologists. Images were assessed for signs of delamination including the presence of a linear area of bright signal intensity along the acetabular subchondral bone and an area of darker tissue at the surface of the acetabular cartilage. All FAI patients underwent surgery; arthroscopy served as the standard of reference.

RESULTS

The mean age of participants was 36.1±10.9 years with 36 (48.6%) women. In the FAI group, arthroscopic surgery showed acetabular chondral delamination in 37 hips. In all hips (including the controls), MRI signs of acetabular cartilage delamination showed an average sensitivity across the three raters of 73.0% with a specificity of 71.0%. In a separate analysis of only the FAI patients, a slightly higher sensitivity (77.7%) but lower specificity (66.7%) was demonstrated. The interrater reliability showed a moderate agreement (average [k]) across the raters (0.450).

CONCLUSION

Performance of non-arthrographic MRI in diagnosing acetabular chondral delamination showed good results, yet inter-observer reproducibility among different radiologists was only moderate. Our results suggest that an increased level of awareness, for signs of delamination using MRI, will be helpful for detecting chondral delamination in patients with a history of FAI.

Lateral to Medial Joint Space Ratio is Predictive of Survivorship After Primary Hip Arthroscopy

PURPOSE

To assess whether preoperative joint space measures would be predictive of survivorship in patients undergoing hip arthroscopy (HA) for femoroacetabular impingement (FAI).

METHODS

Data on consecutive patients who underwent hip arthroscopy between February 2008 and February 2018 were retrospectively reviewed. To be eligible for final analysis, patients were required to have preoperative radiographs for joint space measurements and data indicating conversion to a total hip arthroplasty (THA), hip resurfacing, or neither; at a minimum of 2 years after primary hip arthroscopy. Survivorship following HA was defined as remaining conversion free and served as the primary outcome. A multivariate logistic regression analysis and receiver operator curve (ROC) were used to evaluate the correlation between joint space measurements and survivorship following HA.

RESULTS

A total of 1,885 primary arthroscopy cases were included in this study. The multivariate regression analysis found preoperative lateral-to-medial joint space ratio (L/M ratio) to be the strongest predictive factor of survivorship after primary hip arthroscopy (OR = 2.084, CI_95% = 1.239-3.503; P = .006). The ROC curve for the model demonstrated acceptable discrimination with an area under the curve (AUC) of 0.792. Patients with an L/M ratio ≥0.75 had a survivorship rate of 91.7% compared to a rate of 75% for patients with an L/M ratio <0.75 (OR: 3.68).

CONCLUSIONS

This study found that, of the factors evaluated in this study, the most significant factor in predicting survivorship at 2 years after undergoing primary hip arthroscopy was a larger lateral-to-medial joint space ratio. This may suggest an initiation of primary arthritis at the edge-loading area of the lateral acetabulum. LEVEL OF EVIDENCE: III, retrospective comparative observation study.

Amorphous calcium deposits of the hip joint: current observations and state of the scientific discussion

INTRODUCTION

As a result of increasing hip arthroscopies, rare pathologies as intra-articular amorphous calcium deposits in the capsule-labral (perilabral) recess can be recognized. There is a lack of publications on this pathology. The largest case series included 18 patients. An association between femoroacetabular impingement syndrome (FAIS) and female sex was observed. Furthermore, a correlation between the size of the calcific deposit and the preoperative hip function score was reported. Our hypothesis was that the data of our patient collective with intraoperative amorphous calcium deposits of the hip joint are comparable to the existing data to confirm previous observations.

MATERIALS AND METHODS

From 01/2018 to 08/2020, a total of 714 hip arthroscopies were performed. 12 (1.7%) patients who presented intra-articular amorphous calcium deposits during arthroscopy were included. On radiographs, signs of impingement and osteoarthritis were determined. Characteristics and size of the calcific deposits were examined. Preoperative and at the time of follow-up (23 months), patient-reported outcome scores (PROS) were evaluated. Duration of symptoms, pain medication, comorbidities, and return-to-work were evaluated too.

RESULTS

The PROS of the four female and eight male patients improved significantly. The average size of the calcific deposit was 6.9 mm in the anteroposterior radiographs. Separation of the calcific deposit from the acetabular rim was seen in nine cases. No correlation between deposit sizes and PROS was found. Cam morphology was treated in ten cases. All patients returned to work after a median of 7 weeks (2.5-13 weeks).

CONCLUSION

Amorphous calcium deposits were found in approximately 1% of all hip joints with indication for hip arthroscopy. They are not consistently associated with gender, intra-articular hip pathologies or comorbidities. The clustered occurrence in cam FAI can be justified solely by the fact that impingement is by far the most common indication for hip arthroscopy.

[Acquired hip joint pathologies in childhood]

A number of different acquired pathologies can affect the pediatric hip joint. The classical and relatively common reactive, inflammatory or traumatic entities have to be differentiated from each other. Rarer and very rare pathologies, such as neoplastic entities or tenosynovial giant cell tumor, must also be considered in the differential diagnostics. The correct diagnosis, treatment planning and follow-up monitoring require close coordination between the departments of pediatric radiology and pediatric orthopedics. Sonography often represents the initial diagnostic step, followed by conventional radiography. Further evaluation of hip joint pathologies requires magnetic resonance imaging. In selected cases computed tomography can also be indicated.

High bone mass and cam morphology are independently related to hip osteoarthritis: findings from the High Bone Mass cohort

BACKGROUND

High bone mass (HBM, BMD Z-score ≥  + 3.2) and cam morphology (bulging of lateral femoral head) are associated with greater odds of prevalent radiographic hip osteoarthritis (rHOA). As cam morphology is itself a manifestation of increased bone deposition around the femoral head, it is conceivable that cam morphology may mediate the relationship between HBM and rHOA. We therefore aimed to determine if individuals with HBM have increased odds of prevalent cam morphology. In addition, we investigated whether the relationship between cam and prevalent and incident osteoarthritis was preserved in a HBM population.

METHODS

In the HBM study, a UK based cohort of adults with unexplained HBM and their relatives and spouses (controls), we determined the presence of cam morphology using semi-automatic methods of alpha angle derivation from pelvic radiographs. Associations between HBM status and presence of cam morphology, and between cam morphology and presence of rHOA (or its subphenotypes: osteophytes, joint space narrowing, cysts, and subchondral sclerosis) were determined using multivariable logistic regression, adjusting for age, sex, height, weight, and adolescent physical activity levels. The association between cam at baseline and incidence of rHOA after an average of 8 years was determined. Generalised estimating equations accounted for individual-level clustering.

RESULTS

The study included 352 individuals, of whom 235 (66.7%) were female and 234 (66.5%) had HBM. Included individuals contributed 694 hips, of which 143 had a cam deformity (20.6%). There was no evidence of an association between HBM and cam morphology (OR = 0.97 [95% CI: 0.63-1.51], p = 0.90) but a strong relationship was observed between cam morphology and rHOA (OR = 3.96 [2.63-5.98], p = 5.46 × 10-11) and rHOA subphenotypes joint space narrowing (OR = 3.70 [2.48-5.54], p = 1.76 × 10-10), subchondral sclerosis (OR = 3.28 [1.60-6.60], p = 9.57 × 10-4) and osteophytes (OR = 3.01 [1.87-4.87], p = 6.37 × 10-6). Cam morphology was not associated with incident osteoarthritis (OR = 0.76 [0.16-3.49], p = 0.72).

CONCLUSIONS

The relationship between cam morphology and rHOA seen in other studies is preserved in a HBM population. This study suggests that the risk of OA conferred by high BMD and by cam morphology are mediated via distinct pathways.

[Labral lesions in femoroacetabular impingement syndrome: evidence-based treatment]

BACKGROUND

The acetabular labrum and the adjacent rim cartilage are the primary targets of primary or secondary degeneration processes in the hip joint. Currently, femoroacetabular impingement syndrome (FAIS) is considered the main mechanical pathology leading to chondrolabral damage. The treatment options for labrum tears range from a debridement/resection, repair to augmentation or transplantation.

AIM

Description of surgical treatment options for pathologic changes of the acetabulare labrum and their results with a focus on FAIS.

MATERIALS AND METHODS

A literature search was performed on https://pubmed.ncbi.nlm.nih.gov using the following key words: hip, labrum, therapy, resection, repair, augmentation, reconstruction.

RESULTS

The different surgical procedures as labrum therapy reduce pain and increase the joint function. Labral repair, augmentation, and reconstruction tend to have better results compared to resection but are associated with a higher rate of postoperative intraarticular adhesions.

DISCUSSION

In addition to reducing pain and improving function, the goal of surgical treatment of labrum lesions should be to maintain the functions of the labrum. The labrum should be preserved, in cases of adequate tissue quality and width. In the setting of resective procedures, the resection should be limited to the unstable parts of the labrum. The results of labral augmentation and reconstruction are promising, allowing these procedures to be considered for patients with ongoing symptoms in the revision situation with labral defects or an insufficient residual labrum.

Simultaneous bilateral T1 , T2 , and T1ρ relaxation mapping of the hip joint with magnetic resonance fingerprinting

Quantitative MRI can detect early biochemical changes in cartilage, but its bilateral use in clinical routines is challenging. The aim of this prospective study was to demonstrate the feasibility of magnetic resonance fingerprinting for bilateral simultaneous T₁ , T₂ , and T_1ρ mapping of the hip joint. The study population consisted of six healthy volunteers with no known trauma or pain in the hip. Monoexponential T₁ , T₂ , and T_1ρ relaxation components were assessed in femoral lateral, superolateral, and superomedial, and inferior, as well as acetabular, superolateral, and superomedial subregions in left and right hip cartilage. Aligned ranked nonparametric factorial analysis was used to assess the side's impact on the subregions. Kruskal-Wallis and Wilcoxon tests were used to compare subregions, and coefficient of variation to assess repeatability. Global averages of T₁ (676.0 ± 45.4 and 687.6 ± 44.5 ms), T₂ (22.5 ± 2.6 and 22.1 ± 2.5 ms), and T_1ρ (38.2 ± 5.5 and 38.2 ± 5.5 ms) were measured in the left and right hip, and articular cartilage, respectively. The Kruskal-Wallis test showed a significant difference between different subregions' relaxation times regardless of the hip side (p < 0.001 for T₁ , p = 0.012 for T₂ , and p < 0.001 for T_1ρ ). The Wilcoxon test showed that T₁ of femoral layers was significantly (p < 0.003) higher than that for acetabular cartilage. The experiments showed excellent repeatability with CV_rms of 1%, 2%, and 4% for T₁ , T₂ , and T_1ρ, respectively. It was concluded that bilateral T₁ , T₂ , and T_1ρ relaxation times, as well as B₁⁺ maps, can be acquired simultaneously from hip joints using the proposed MRF sequence.

Editorial Commentary: Low-Radiation Dose 3-Dimensional Computed Tomography Scan Reconstruction Is the Best Way to Visualize the Anterior Inferior Iliac Spine-For Now

Femoroacetabular impingement comes in several anatomic variations that may coexist, and subspine impingement is a commonly discussed cause of indirect extra-articular hip pathology. Although a classification system to identify and understand anterior inferior iliac spine morphology has been in place for some time, attempts have been made to visualize and understand the anatomy based on other imaging modalities. Standard radiographs are a common part of the initial patient evaluation pathway, along with thorough history taking and physical examination findings. Magnetic resonance imaging scans are obtained typically to evaluate the soft tissue, muscle, ligaments, articular cartilage, and labrum for pathology. For many hip preservation surgeons, a computed tomography scan with 3-dimensional reconstruction is standard protocol for patients who progress along the treatment pathway toward a surgical procedure because understanding the complex hip anatomy is key to successful surgical treatment. Many hip arthroscopy patients are in their young adult years, and we always attempt to reduce the amount of radiation exposure. Eliminating this computed tomography scan and using standard-of-care magnetic resonance imaging to simplify patient care, reduce radiation, and reduce health care costs would certainly be beneficial to our hip preservation patients.

Safe surgical hip dislocation for acetabular osteoid osteoma excision

Excision of acetabular osteoid osteoma is technically difficult. We report osteoid osteoma of the quadrilateral plate in a 9-year-old girl who presented to us with persistent nocturnal pain, limp and restricted hip joint movement. The child was investigated with CT scan, MRI and triple-phase bone scan. The 0.7 cm nidus was located in the central portion of the cancellous bone in the quadrilateral plate, 1.94 cm inferior to the triradiate cartilage. The child was operated on through the safe surgical dislocation of the left hip. The location of the lesion was gauged from the preoperative CT scan measurement data and intraoperative fluoroscopic aid. The nidus with a sclerotic rim was burred down completely. Postoperative X-ray and CT scan revealed complete excision of the tumour, and the patient was pain-free. At 18 months follow-up, the patient is completely asymptomatic and walking normally.

Adverse Local Tissue Reactions are Common in Asymptomatic Individuals After Hip Resurfacing Arthroplasty: Interim Report from a Prospective Longitudinal Study

BACKGROUND

The evaluation of the natural history prevalence of adverse local tissue reactions (ALTRs) using MRI has focused only on metal-on-metal (MoM) bearing surfaces without comparison to nonMoM bearing surfaces.

QUESTIONS/PURPOSES

To determine (1) the longitudinal changes and differences in blood metal ion levels in patients with hip resurfacing arthroplasty (HRA), ceramic-on-ceramic (CoC) THA, and metal-on-polyethylene (MoP) THA compared with those undergoing ceramic-on-polyethylene (CoP) THA; (2) how the longitudinal change of synovial reaction classification in patients with HRA, CoC THA, and MoP THA compares with those undergoing CoP THA, and whether there is an association between the presence of an ALTR or metallosis on MRI with corresponding patient-reported outcomes, or the presence of capsular dehiscence; and (3) differences in blood metal ion levels between patients undergoing HRA with an ALTR or metallosis on MRI and those with HRA without these conditions.

METHODS

Between March 2014 and February 2019, 22,723 patients underwent primary HRA and THA at one center. Patients received an HRA based on their desired athletic level after surgery and the presence of normal acetabular and proximal femoral bone morphology without osteopenia or osteoporosis. Two percent (342 of 22,723) of patients were contacted to participate, and 71% (243 of 342 hips in 206 patients) were enrolled for analysis at baseline. The patients underwent arthroplasty for degenerative joint disease, and 25 patients withdrew over the course of the study. We included patients who were more than 1 year postarthroplasty. All participants had an MRI examination and blood serum ion testing and completed a Hip Disability and Osteoarthritis Outcome Score survey annually for four years (baseline, year 1, year 2, year 3). Morphologic and susceptibility-reduced MR images were evaluated by a single radiologist not involved in the care of patients for the presence and classification of synovitis (Gwet AC1: 0.65 to 0.97), synovial thickness, and volume (coefficient of repeatability: 1.8 cm3). Linear mixed-effects models were used to compare the mean synovial thickness, synovial volume, and Hip Disability and Osteoarthritis Outcome Score subscales between bearing surfaces at each timepoint and within each bearing surface over time. Marginal Cox proportional hazards models were used to compare the time to and the risk of developing ALTR only, metallosis only, and ALTR or metallosis between bearing surfaces. All models were adjusted for age, sex, BMI, and length of implantation based on known confounders for hip arthroplasty. Adjustment for multiple comparisons was performed using the Dunnett-Hsu method.

RESULTS

Patients with unilateral HRA had higher cobalt and chromium serum ion levels (baseline: 1.8 ± 0.8 ppb, year 1: 2.0 ± 1.5 ppb, year 2: 2.1 ± 1.2 ppb, year 3: 1.6 ± 0.7 ppb) than those with unilateral CoP bearings (baseline: 0.0 ± 0.1 ppb, year 1: 0.1 ± 0.3 ppb, year 2: 0.0 ± 0.2 ppb, year 3: 0.0 ± 0.0 ppb) at all timepoints (p < 0.001 for each time point). More patients who received an HRA developed ALTR or metallosis on MRI than did patients with CoP bearings (hazard ratio 4.8 [95% confidence interval 1.2 to 18.4]; p = 0.02). There was no association between the longitudinal change of synovial reaction to ALTR or metallosis on MRI with patient-reported outcomes. In addition, there was no association between the presence of dehiscence at baseline and the subsequent development of ALTR or metallosis, as seen on MRI. There were elevated cobalt (4.7 ± 3.5 ppb) and chromium (4.7 ± 2.6 ppb) serum levels in patients with unilateral HRA who had an ALTR or metallosis present on MRI at year 1 compared with patients without an ALTR or metallosis on MRI (cobalt: 1.8 ± 1.0 ppb, mean difference 4.7 ppb [95% CI 3.3 to 6.0]; p < 0.001; chromium: 2.3 ± 0.5 ppb, mean difference 3.6 ppb [95% CI 2.2 to 5.0]; p < 0.001) as well as for chromium at year 3 (3.9 ± 2.4 ppb versus 2.2 ± 1.1 ppb, mean difference 1.3 ppb [95% CI 0.3 to 2.4]; p = 0.01).

CONCLUSION

We found a higher proportion of ALTR or metallosis on MRI in patients with HRA compared with patients with CoP, even when patient self-assessed symptomatology of those with an ALTR or metallosis on MRI was not different than the absence of these features. MRI detected ALTRs in high-function patients, emphasizing that an annual clinical assessment dependent on survey or blood ion testing alone may not detect soft tissue complications. The results of this study are in line with prior consensus recommendations of using MRI as part of a routine follow-up protocol for this patient population.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Hip Morphology in Early-stage LCPD: Is There an Argument for Anatomic-specific Containment?

BACKGROUND

Early containment surgery has become increasingly popular in Legg-Calvé-Perthes Disease (LCPD), especially for older children. These procedures treat the proximal femur, the acetabulum, or both, and most surgeons endorse the same surgical option regardless of an individual patient's anatomy. This "one-surgery-fits-all" approach fails to consider potential variations in baseline anatomy that may make one option more sensible than another. We sought to describe hip morphology in a large series of children with newly diagnosed LCPD, hypothesizing that variation in anatomy may support the concept of anatomic-specific containment.

METHODS

A retrospective review of a prospectively collected multicenter database was conducted for patients aged 6 to 11 at diagnosis. To assess anatomy before significant morphologic changes secondary to the disease itself, only patients in Waldenström stages IA/IB were included. Standard hip radiographic measurements including acetabular index, lateral center-edge angle, proximal femoral neck-shaft angle (NSA), articulotrochanteric quartiles, and extrusion index (EI) were made on printed anteroposterior pelvis radiographs. Age-specific percentiles were calculated for these measures using published norms. Significant outliers (≤10th/≥90th percentile) were reported where applicable.

RESULTS

A total of 168 patients with mean age at diagnosis of 8.0±1.3 years met inclusion criteria (81.5% male). Mean acetabular index for the entire cohort was 16.8±4.1 degrees; 58 hips (34.5%) were significantly dysplastic compared with normative data. Mean lateral center-edge angle was 15.9±5.2 degrees at diagnosis; 110 (65.5%) were ≤10th percentile indicating dysplasia (by this metric). Mean NSA overall was 136.5±7.0 degrees. Fifty-one (30.4%) and 20 (11.9%) hips were significantly varus (≤10th percentile) or valgus (≥90th percentile), respectively. Thirty-five hips (20.8%) were the third articulo-trochanteric quartiles or higher suggesting a higher-riding trochanter at baseline. Mean EI was 15.5%±9.0%, while 63 patients (37.5%) had an EI ≥20%.

CONCLUSIONS

The present study finds significant variation in baseline anatomy in children with early-stage LCPD, including a high prevalence of coexisting acetabular dysplasia as well as high/low NSAs. These variations suggest that the "one-surgery-fits-all" approach may lack specificity for a particular patient; a potentially wiser option may be an anatomic-specific containment operation (eg, acetabular-sided osteotomy for coexisting dysplasia, varus femoral osteotomy for valgus NSA).

LEVEL OF EVIDENCE

Level IV.

The New Bern Chondrolabral Classification Is Reliable and Reproducible

BACKGROUND

Several classification systems have been used to describe early lesions of hip cartilage and the acetabular labrum in young adults with hip pain. Some of them were introduced before the concept of femoroacetabular impingement was proposed. Others were developed for other joints (such as the patellofemoral joint). However, these often demonstrate inadequate reliability, and they do not characterize all possible lesions. Therefore, we developed a novel classification system.

QUESTION/PURPOSE

We asked: What is the (1) intraobserver reliability, (2) interobserver reproducibility, and (3) percentage of nonclassifiable lesions of the new classification system for damage to the hip cartilage and labrum compared with six established classification systems for chondral lesions (Beck et al. [4], Konan et al. [10], Outerbridge et al. [14]) and labral lesions (Beck et al. [3], Lage et al. [12], Peters and Erickson [15])?

METHODS

We performed a validation study of a new classification system of early chondrolabral degeneration lesions based on intraoperative video documentation taken during surgical hip dislocations for joint-preserving surgery in 57 hips (56 patients) performed by one surgeon with standard video documentation of intraarticular lesions. The exclusion criteria were low-quality videos, inadequate exposure angles, traumatic lesions, and incomplete radiographic documentation. This left 42 hips (41 patients) for the blinded and randomized analysis of six raters, including those with cam-pincer-type femoroacetabular impingement (FAI) (19 hips in 18 patients), isolated cam-type FAI (10 hips), extraarticular FAI due to femoral anteversion (seven hips), isolated pincer-type FAI (two hips), focal avascular necrosis (two hips), localized pigmented villonodular synovitis (one hip), and acetabular dysplasia as a sequelae of Perthes disease (one hip). The raters had various degrees of experience in hip surgery: Three were board-certified orthopaedic fellows and three were orthopaedic residents, in whom we chose to prove the general usability of the classification systems in less experienced readers. Every rater was given the original publication of all existing classification systems and a visual guide of the new Bern classification system. Every rater classified the lesions according the existing classifications (cartilage: Beck et al. [4], Konan et al. [10], and Outerbridge et al. [14]; labrum: Beck et al. [3], Peters and Erickson [15], and Lage et al. [12]) and our new Bern chondrolabral classification system. The intraclass correlation coefficient with 95% confidence interval was used to assess the intraobserver reliability and interobserver reproducibility. The percentage of nonclassifiable lesions was calculated as an absolute number and percentage.

RESULTS

The intraobserver intercorrelation coefficients (ICCs) for cartilage lesions were as follows: the Bern classification system (0.68 [95% CI 0.61 to 0.70]), Beck (0.44 [95% CI 0.34 to 0.54]), Konan (0.39 [95% CI 0.29 to 0.49]), and the Outerbridge classification (0.57 [95% CI 0.48 to 0.65]). For labral lesions, the ICCs were as follows: the Bern classification (0.70 [95% CI 0.63 to 0.76]), Peters (0.42 [95% CI 0.31 to 0.51]), Lage (0.26 [95% CI 0.15 to 0.38]), and Beck (0.59 [95% CI 0.51 to 0.67]). The interobserver ICCs for cartilage were as follows: the Bern classification system (0.63 [95% CI 0.51 to 0.75), the Outerbridge (0.14 [95% CI 0.04 to 0.28]), Konan (0.58 [95% CI 0.40 to 0.76]), and Beck (0.52 [95% CI 0.39 to 0.66]). For labral lesions, the ICCs were as follows: the Bern classification (0.61 [95% CI 0.49 to 0.74]), Beck (0.31 [95% CI 0.19 to 0.46]), Peters (0.28 [95% CI 0.16 to 0.44]), and Lage (0.20 [95% CI 0.09 to 0.35]). The percentage of nonclassifiable cartilage lesions was 0% for the Bern, 0.04% for Beck, 17% for Konan, and 25% for the Outerbridge classification. The percentage of nonclassifiable labral lesions was 0% for Bern and Beck, 4% for Peters, and 25% for Lage.

CONCLUSION

We have observed some shortcomings with currently used classification systems for hip pathology, and the new classification system we developed seems to have improved the intraobserver reliability compared with the Beck and Konan classifications in cartilage lesions and with the Peters and Lage classifications in labral lesions. The interrater reproducibility of the Bern classification seems to have improved in cartilage lesions compared with the Outerbridge classification and in labral lesions compared with the Beck, Peters, and Lage classifications. The Bern classification identified all present cartilage and labral lesions. It provides a solid clinical basis for accurate descriptions of early degenerative hip lesions independent of etiology, and it is reproducible enough to use in the reporting of clinical research. Further studies need to replicate our findings in the hands of nondevelopers and should focus on the prognostic value of this classification and its utility in guiding surgical indications.

LEVEL OF EVIDENCE

Level II, diagnostic study.

Differences between 3D isovoxel fat suppression VIBE MRI and CT models of proximal femur osseous anatomy: A preliminary study for bone tumor resection planning

Purpose

To evaluate the osseous anatomy of the proximal femur extracted from a 3D-MRI volumetric interpolated breath-hold (VIBE) sequence using either a Dixon or water excitation (WE) fat suppression method, and to measure the overall difference using CT as a reference standard.

Material and methods

This retrospective study reviewed imaging of adult patients with hip pain who underwent 3D hip MRI and CT. A semi-automatically segmented CT model served as the reference standard, and MRI segmentation was performed manually for each unilateral hip joint. The differences between Dixon-VIBE-3D-MRI vs. CT, and WE-VIBE-3D-MRI vs. CT, were measured. Equivalence tests between Dixon-VIBE and WE-VIBE models were performed with a threshold of 0.1 mm. Bland–Altman plots and Lin’s concordance-correlation coefficient were used to analyze the agreement between WE and Dixon sequences. Subgroup analyses were performed for the femoral head/neck, intertrochanteric, and femoral shaft areas.

Results

The mean and maximum differences between Dixon-VIBE-3D-MRI vs. CT were 0.2917 and 3.4908 mm, respectively, whereas for WE-VIBE-3D-MRI vs. CT they were 0.3162 and 3.1599 mm. The mean differences of the WE and Dixon methods were equivalent (P = 0.0292). However, the maximum difference was not equivalent between the two methods and it was higher in WE method. Lin’s concordance-correlation coefficient showed poor agreement between Dixon and WE methods. The mean differences between the CT and 3D-MRI models were significantly higher in the femoral shaft area (P = 0.0004 for WE and P = 0.0015 for Dixon) than in the other areas. The maximum difference was greatest in the intertrochanteric area for both techniques.

Conclusion

The difference between 3D-MR and CT models were acceptable with a maximal difference below 3.5mm. WE and Dixon fat suppression methods were equivalent. The mean difference was highest at the femoral shaft area, which was off-center from the magnetization field.

Comparison of clinical and radiographic signs of hip osteoarthritis in contralateral hip joints of fifty working dogs

OBJECTIVE

This study aimed to compare the symmetry of clinical and radiographic signs of right and left pelvic limbs of dogs with bilateral hip osteoarthritis (OA) and evaluate the association of physical findings and radiographic abnormalities.

PATIENTS AND METHODS

One hundred pelvic limbs of police working dogs with bilateral hip OA were evaluated, following a screening program. Weight distribution, joint range of motion at flexion and extension, thigh girth, and radiographic signs were recorded and compared with the results of the contralateral limb and by breed, age, and sex with the Paired Samples T-Test and Pearson correlation coefficient, with p<0.05.

RESULTS

The sample mean age was 6.5±2.2 years, and the bodyweight of 26.7±5.3kg. No significant differences were observed when comparing weight distribution, joint range of motion, and thigh girth of left and right limbs. Weight distribution and age showed a statistically significant correlation with joint extension. The right limbs showed a significantly higher frequency of circumferential femoral head osteophyte (CFHO) regarding radiographic signs. Limbs with CFHO or caudolateral curvilinear osteophyte had significantly larger joint flexion angle (p = 0.02) and smaller extension angle (p<0.01), respectively, compared to those that did not. Age showed a significant correlation with the presence of several radiographic findings, as did different breeds.

CONCLUSION

Clinical and radiographic signs occur symmetrically in naturally occurring hip OA in police working dogs. Several correlations were observed between the evaluations performed and differences between breeds, which can be useful in assessing and early diagnosis of hip OA.

Why Does Hip Arthroscopy Fail? Indications and PEARLS for Revision Success

The surgical treatment of femoroacetabular impingement has been shown to have successful early and mid-term clinical outcomes. Despite these favorable clinical outcomes that have been published in the literature, there is a subgroup of patients that present with continued or recurrent symptoms after surgical treatment. Not only has there been an increase in the number of hip arthroscopy procedures, but also there has been a corresponding increase in the number of revision hip arthroscopy and hip preservation surgeries. Previous studies have reported residual deformity to be the most common reason for revision hip arthroscopy. However, chondral, labral, and capsular considerations also are important when addressing patients not only in the primary but also, the revision setting. In this review, we outline the evaluation and treatment of the patient that presents with continued hip and groin pain after undergoing a hip.

[A man with groin pain]

A 78-year-old man was evaluated at the outpatient orthopaedic clinic with progressive pain in the right groin. X-ray revealed osteoarthritis of the right hip and fibrous dysplasia of the proximal femur. Total hip arthroplasty was performed using a cemented long-stem femoral component spanning the entire lesion.

Retroperitoneal Approach for Excision of Wear-Debris Pseudotumor: A Case Report

CASE

Pelvic pseudotumors may occur as a reaction to wear-debris after hip arthroplasty and are rarely treated with surgery. We describe an instance in which a pelvic pseudotumor along the iliopsoas muscle tendon sheath was debulked using a retroperitoneal approach in a patient presenting for treatment of a prosthetic hip infection. The patient recovered uneventfully and was ambulatory with a new hip prosthesis at 3 months after procedure.

CONCLUSIONS

Retroperitoneal exposure provided safe, excellent exposure to a wear-debris pelvic pseudotumor in this case.

Circ_0088194 Promotes the Invasion and Migration of Rheumatoid Arthritis Fibroblast-Like Synoviocytes via the miR-766-3p/MMP2 Axis

Dysregulation of circular RNAs (circRNAs) is involved in various human diseases. Fibroblast-like synoviocytes (FLSs), which form the lining of the joint, are epigenetically imprinted with an aggressive phenotype and contribute to joint destruction in rheumatoid arthritis (RA). In the present study, we identified a novel circRNA, Circ_0088194, which was upregulated in RA fibroblast-like synoviocytes (RA-FLSs) and correlated with the disease activity score in 28 joints. Overexpression of Circ_0088194 promoted RA-FLS migration and invasion, while inhibition of Circ_0088194 had the opposite effect. Mechanistically, Circ_0088194 acted as a miR-766-3p sponge to relieve the repressive effect of miR-766-3p on its target, MMP2 (encoding matrix metalloproteinase 2), thereby promoting migration and invasion. The expression level of Circ_0088194 was inversely correlated with that of miR-766-3p in RA-FLSs. Importantly, overexpression of miR-766-3p partially blocked the migration and invasion induced by Circ_0088194 overexpression. Collectively, this study identified a novel circRNA Circ_0088194 that promotes RA-FLS invasion and migration via the miR-766-3p/MMP2 axis. Circ_0088194 might represent a novel therapeutic target to prevent and treat RA.

Evaluation of Hip Pain and Management of Toxic Synovitis in the Ultrasound Era

ABSTRACT

The cause of acute onset hip pain in children can be difficult to determine. Once trauma is excluded, the workup revolves around determining whether there is a hip effusion and eliminating orthopedic emergencies. Point-of-care-ultrasound can be used as an adjunct in the workup. In this article, we review (1) differential diagnosis of hip pain, with a focus on toxic synovitis; (2) the evaluation of a hip for the presence of effusion, including the point-of-care ultrasound technique; and (3) the management of toxic synovitis.

Asymmetric midshaft femur remodeling in an adult male with left sided hip joint ankylosis, Metal Period Nagsabaran, Philippines

OBJECTIVE

This study investigated microstructural changes of the right and left midshaft femur in an archaeological individual afflicted with left-sided hip joint ankylosis to assess whether increased cortical porosity was present as a result of leg disuse.

MATERIALS

The individual is a middle-aged adult male excavated from the Metal Period (∼2000 BP) Nagsabaran, Luzon Island, Philippines.

METHODS

Following standard examination of femur gross anatomy and differential diagnosis of the hip joint fusion, ∼1 cm thick posterior midshaft femur samples were removed for microstructural examination. Using static histomorphometry, bone multi-cellular unit activity from Haversian canal (vascular pore) density, area, and circularity was reconstructed. Spatial positioning of Haversian canals was mapped using Geographic Information Systems software. Phosphate, carbonate, and carbonate:phosphate ratios were obtained using synchrotron-sourced Fourier transform infrared microspectroscopy.

RESULTS

The left femur had greater cortical pore density, with smaller and rounder vascular canals, in addition to lower matrix levels of phosphate and carbonate, when compared to the right femur.

CONCLUSIONS

Our data indicate compromised bone tissue in the left femur, and conform to expected bone functional adaptation paradigms of remodeling responses to pathological and biomechanical changes.

SIGNIFICANCE

The preservation of this individual's hip abnormality created a unique opportunity to evaluate intra-skeletal bone health asymmetry, which may help other researchers evaluate the presence of limb disuse in archaeological samples.

LIMITATIONS

A lack of lower limb data limits our interpretations to femur remodeling only.

SUGGESTIONS FOR FURTHER RESEARCH

Future research efforts should aim to examine the presence of remodeling changes in all bones of the lower limb.

LAYUNIN

Gamit ang buto ng magkabilang pemur ng isang taong natagpuan sa isang archaeological site na may sakit na ankylosis sa kaliwang balakang, pinag-aralan ang iba't-ibang microstructures galing sa gitnang bahagi o midshaft ng pemur upang malaman kung may makikitang mataas na cortical porosity ang buto dahil hindi ito malimit gamitin.

GAMIT

Ang pinag-aaralang buto ay galing sa isang indibidwal na tinatayang middle-age na lalaki na namuhay noong Panahon ng Metal (∼2000 BP) sa Nagsabaran, Cagayan, Republika ng Pilipinas.

PAMAMARAAN

Matapos ang unang pagkilatis sa femur at ang pagkilala ng sakit sa balakang, kumuha ng ∼1 sentimetro ng buto galing sa midshaft ng pemur upang lalong mapag-aralan ang kanyang microstructure. Gamit ang static histomorphometry, napag-aralan ang mga naiwang bakas ng multi-cellular unit activity ayon sa kapal, laki at pagkakabilog ng Haversian canal (vascular pore). Gumamit din ng Geographic Information Systems (GIS) software upang mapag-aralan ang kaugnayan ng posisyon ng Haversian canal. Panghuli, gumamit din ng synchroton-sourced Fourier transform infrared (sFTIR) microspectroscopy upang makuha ang bilang ng phosphate, carbonate, at carbonate:phosphate ratio.

RESULTA

Napag-alaman na ang kaliwang pemur ay mayroong higit na maraming cortical pores, maliit at mabilog na vascular canals, at mababang bilang ng phosphate, carbonate kung ihahambing sa kanang pemur.

KONKLUSYON

Ayon sa aming datos, ang kaliwang pemur ay umaayon sa mga katangian ng isang butong may sakit. Sumunod din ito sa inaasahang bone functional adaptation paradigms of remodeling ng buto dahil may sakit at hindi nagamit.

KAHALAGAHAN

Dahil maganda ang pagkakalibing ng buto ng balakang, nagkaroon ng pagkakataong makilatis ang kalusugan ng sinaunang-tao sa pamamagitan ng pag-aaral ng kalusugan ng buto. Dagdag pa, makakatulong din ito upang malaman kung ibang mananaliksik ang pag-aaral ng ibang butong hindi nagagamit mula sa archaeological site.

LIMITASYON

Dahil walang nakuhang ibang buto mula sa binti at paa, ang pemur lang ang naimbestigahan.

MUNGKAHI PARA SA MGA SUSUNOD NA PAG-AARAL

Kung magkakaroon ng pagkakataon sa susunod, dapat maimbistigahan ang lahat ng buto ng binti (lower limb).

The Effect of Total Hip Arthroplasty Surgical Technique on Postoperative Muscle Atrophy

A variety of surgical approaches are used for total hip arthroplasty (THA). Controversy still exists regarding whether the direct anterior approach truly minimizes muscle damage. The purpose of this study was to determine the effect of surgical approach for THA on muscle atrophy quantified through magnetic resonance imaging (MRI). The study included 25 hips in patients with a mean age of 64.72±8.35 years who underwent a primary unilateral THA for severe osteoarthritis. Patients were grouped according to surgical approach: direct anterior (n=9), direct lateral (n=9), and posterior (n=7). Magnetic resonance images were collected at the 24-week postoperative time point to assess atrophy/fatty infiltration of the hip musculature. All MRIs were assessed by a fellowship-trained radiologist who was blinded to all clinical information. There were no significant differences preoperatively and 1 year postoperatively between the surgical approach groups in terms of patient-reported outcome measures (P>.05). Significant differences in fatty infiltration differences between surgical approaches were observed in the gluteus medius, gluteus minimus, iliacus, obturator externus, obturator internus, pectineus, psoas, quadratus femoris, sartorius, and vastus intermedius (P<.05). The direct anterior approach to THA resulted in less atrophy of the hip musculature compared with a direct lateral or posterior approach; however, there were no differences in patient-reported clinical outcome scores at 1 year between the surgical approaches. [Orthopedics. 2020;43(6):361-366.].

Correlations Between Hip Extension Range of Motion, Hip Extension Asymmetry, and Compensatory Lumbar Movement in Patients with Nonspecific Chronic Low Back Pain

BACKGROUND This study aimed to confirm the correlations among hip extension range of motion, hip extension asymmetry, pain intensity, disability index, and compensatory lumbar movement in patients with nonspecific chronic low back pain. MATERIAL AND METHODS Of 66 patients with nonspecific chronic low back pain and limited hip extension, 59 met the inclusion criteria and were enrolled in the study. Pain intensity, Oswestry Disability Index (ODI), hip range of motion, compensatory lumbar extension, and compensatory lumbar rotation of the subjects were assessed. Pain was measured using a numeric pain rating scale (NPRS), and hip extension range of motion and compensatory lumbar movement were evaluated using a digital dual inclinometer (Dualar IQ, JTech Medical, United States). Correlation analysis was used to analyze the data. RESULTS A strong correlation was observed among hip extension asymmetry, pain intensity, and disability index (P<0.05). However, no correlation was observed among compensatory lumbar rotation and extension, pain intensity, and ODI. A strong correlation also was observed between limited hip extension range of motion and compensatory lumbar rotation (P<0.05) but not between limited hip extension range of motion and compensatory lumbar extension (P>0.05). CONCLUSIONS The results of this study showed that hip extension asymmetry might be a more critical factor than hip extension range of motion. The strong correlation between limited hip extension and compensatory lumbar rotation suggests a risk of micro-trauma due to compensatory lumbar rotation.

Unusual presentation of rheumatic fever in a 3-year-old child in the UK

In the developed world, acute rheumatic fever (ARF) is rare. When it does arise, symptoms commonly include fever, arthralgia and rash. We describe a presentation of a 3-year-old child with ARF in a UK District General Hospital. The patient had a 6-week history of diarrhoea, rash and intermittent right hip arthralgia. This was initially thought to be a viral illness until she re-presented with shortness of breath and fever with a pan-systolic murmur. A throat-culture was negative, but an anti-streptolysin titre was elevated, with a bedside echocardiogram demonstrating moderate to severe mitral regurgitation. The young child was transferred to the local tertiary centre for further management; however, she went on to develop acute left ventricular failure. This case illustrates the need to be vigilant for the presentation of a rare illness, such as rheumatic fever, as there can be significant impacts on the quality of life of young patients.

A Clinician's Guide to Femoacetabular Impingement in Athletes

Femoroacetabular impingement (FAI) is the most common cause of hip pain in both professional and recreational athletes. It is caused by abnormal bone development on both the acetabulum and proximal femur as a result of genetic factors and in reaction to high-volume athletics participation. Athletes typically become symptomatic after reaching skeletal maturity and commonly describe deep groin pain that worsens with activities such as squatting, cutting, or pivoting motions. For this reason, sports such as hockey, football, and soccer can be particularly irritating to an athlete with FAI. Moreover, the athlete with FAI often presents with contaminant hip and pelvis pathologies such as athletic pubalgia and iliopsoas tendinopathy that must also be addressed. While this pain often limits performance or participation in sports, perhaps the most significant ramification of FAI is the role it plays in driving early onset osteoarthritis. Fortunately, FAI can be reliably diagnosed through careful history taking, appropriate provocative physical exam maneuvers, and familiarity with hallmark radiographic features. The aims of this review are to provide clinicians with information regarding the pathogenesis of FAI, to thoroughly describe the classic history and physical exam elements, and to introduce various management strategies for athletes suffering from FAI.

Bifid iliopsoas tendon as a cause for internal snapping hip syndrome: A case report

Snapping hip syndrome, or coxa saltans, can result in significant clinical manifestations in patients including pain and limited mobility. A variety of both intra- and extra-articular pathologies have been implicated in snapping hip, including an anatomic variant known as the bifid iliopsoas tendon which has been briefly described in the literature. We report a case of a bifid iliopsoas tendon leading to internal snapping hip syndrome which was ultimately successfully treated with surgical release, including review of the clinical presentation, pathophysiology, and dynamic sonographic findings.

Ultrasound Definitions and Findings in Greater Trochanteric Pain Syndrome: A Systematic Review

Ultrasound (US) assists in the determination of the pathology underlying greater trochanteric pain syndrome (GTPS); however, there exists no consensus regarding the US criteria used to define these pathologies. We aim to explore these US definitions and their associated prevalence. "Trochanteric bursitis" was defined in 10 studies (13 included studies) and was heterogeneously described. "Tendinopathy" was defined in 4 studies, while 7 studies defined "tendinosis." "Tendon tears" were defined in 8 studies, 6 of which distinguished between "partial- and full-thickness tears." Tendon pathology was most frequent in 5 studies (prevalence: 7%-93%), and bursitis in 2 studies (prevalence: 10%-75%); 3 studies had equal distribution. Methodological quality was limited in the descriptions of GTPS and US approaches. Together, we document the lack of standardized US definitions of the pathologies underlying GTPS. This may explain the heterogenous prevalence of US findings. Standardized definitions are needed to improve the reliability of future GTPS studies.

Multivariate use of MRI biomarkers to classify histologically confirmed necrosis in symptomatic total hip arthroplasty

The failure of total hip arthroplasty (THA) is commonly associated with the necrosis of the periprosthetic tissue. To date, there is no established method to noninvasively quantify the progression of such necrosis. Magnetic resonance imaging (MRI) of soft tissues near implants has undergone a recent renaissance due to the development of multispectral metal-artifact reduction techniques. Advanced analysis of multispectral MRI has been shown capable of detecting small magnetism effects of metallic debris in periprosthetic tissue. The purpose of this study is to demonstrate the diagnostic utility of these MRI-based tissue-magnetism signatures. Together with morphological MRI metrics, such as synovial volume and thickness, these measurements are utilized as biomarkers to noninvasively detect soft-tissue necrosis in symptomatic THA patients ( N = 78 ). All subjects underwent an advanced MRI scan before revision surgery and tissue biopsies utilized for necrosis grading. Statistical analyses demonstrated a weak, but significant positive correlation (P = .04) between MRI magnetism signatures and necrosis scores, while indicating no meaningful association between the latter and serum cobalt and chromium ion levels. Receiver-operating characteristic (ROC) analyses were then performed based on uni- and multivariate logistic regression models utilizing the measured MRI biomarkers as predictors of severe necrosis. The area under the curve of the ROC plots for MRI biomarkers as combined predictors were found to be 0.70 and 0.84 for cross-validation and precision-recall tests, respectively.

Piezo2 expressed in proprioceptive neurons is essential for skeletal integrity

In humans, mutations in the PIEZO2 gene, which encodes for a mechanosensitive ion channel, were found to result in skeletal abnormalities including scoliosis and hip dysplasia. Here, we show in mice that loss of Piezo2 expression in the proprioceptive system recapitulates several human skeletal abnormalities. While loss of Piezo2 in chondrogenic or osteogenic lineages does not lead to human-like skeletal abnormalities, its loss in proprioceptive neurons leads to spine malalignment and hip dysplasia. To validate the non-autonomous role of proprioception in hip joint morphogenesis, we studied this process in mice mutant for proprioceptive system regulators Runx3 or Egr3. Loss of Runx3 in the peripheral nervous system, but not in skeletal lineages, leads to similar joint abnormalities, as does Egr3 loss of function. These findings expand the range of known regulatory roles of the proprioception system on the skeleton and provide a central component of the underlying molecular mechanism, namely Piezo2.