Prevalence of pincer, cam, and combined deformities in Japanese hip joints evaluated with the Japanese Hip Society diagnostic guideline for femoroacetabular impingement: A CT-based study

The ability of plain radiography to accurately describe the bone surface at the head-neck junction of the femur: a study using human bone models

In evaluations of a cam deformity on femoroacetabular impingement, the head-neck junction (HNJ) must be accurately assessed. We conducted this study to determine the ability of plain radiography to visualize the end-to-end bone surface of the HNJ. We used six human bone models. Ten examiners evaluated the degree to which attached stainless wire marker at the 1:00, 1:30, and 2:00 radial plane defined in reconstructed computed tomography can be accurately detected on the bone surface on plain radiographies. We employed 13 plain radiographies: the cross-table lateral view, frog-leg lateral view, Espié frog-leg lateral view, false-profile view, modified false-profile view, 30° Dunn view (DV), 45° DV, 60° DV, 90° DV, 30° modified Dunn view (MDV), 45° MDV, 60° MDV, and 90° MDV. Examiners scored the degree to which the radiographic images accurately detected the stainless wire marker on the bone surface of the HNJ on a scale of 1 point (0% match) to 5 points (almost 100% match). The highest score for the 1:00 plane was 4.98 points on the 45° DV. Similarly, the highest scores of the 1:30 and 2:00 planes were 4.98 points for the 45° MDV and 4.68 points for the 90° MDV, respectively. On these bone model studies, the most suitable plain radiography for describing the HNJ at the 1:00, 1:30, and 2:00 planes were both the 45° DV, the 45° MDV, and the 90° MDV, respectively.

Trends in hip preservation surgery in Japan from 2014 to 2019 with a focus on hip arthroscopic surgery

Secondary hip osteoarthritis due to hip dysplasia is common among Japanese populations. This study aimed to investigate the number of hip preservation surgeries performed in Japan and assess trends, by age and sex, from 2014 to 2019, focusing on hip arthroscopic surgery, based on the National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB). We downloaded the files 'Number of calculations by division, sex, and age group' under 'operation (code K)' from 2014 to 2019 from the NDB Open Data Japan database. Data on hip preservation surgeries were extracted, including the number for each surgical procedure and its incidence per year, calculated as the number of surgeries performed for each 10-year age group and by sex, regarding hip arthroscopic surgery. Overall, 14 891 hip preservation surgeries were performed in Japan over the study period, with pelvic osteotomy being the most common procedure. Although the incidence of hip preservation surgeries decreased from 2014 to 2019, there was a specific 1.54-fold higher incidence in hip arthroscopic procedures in 2019 compared to 2014. Hip arthroscopic labral repair was performed more frequently than synovectomy. The highest incidence of hip arthroscopic surgery was in the 40- to 49-years age group, with no difference in incidence between sexes (P = 0.951). In Japan, pelvic osteotomy was performed more often as a hip preservation surgery than hip arthroscopic surgery. Although hip arthroscopic surgery was developed in Japan, its use has not increased from 2017 to 2019.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

Level III, diagnostic study.

The natural history of alpha angle in the last seventeen centuries

INTRODUCTION

Hip osteoarthritis is one of the most important and debilitating diseases affecting thousands of people all over the world. On the other hand, femoroacetabular impingement (FAI) is one of the known important causes of hip osteoarthritis. Cam deformity frequently presents in FAI showing an increased alpha angle. Increased alpha angle has been observed among young patients involved in demanding physical activities such as in sports (40-60%), whereas among the non-athletic population, increased alpha angle was observed in 15-20%. Although femoroacetabular pathology has been described over the recent years, it is not possible to determine when the angle increase actually begins prior to diagnosis. The aim of our study is to evaluate the femoral alpha angle in different human femurs in different civilization eras in West Mediterranean area.

MATERIALS AND METHODS

Available ancient femurs were selected from the Collection Center belonging to the archeological archives (ancient necropolis) from the fourth, fourteenth and eighteenth centuries. A comparison of the alpha angle was made of the measurements from the different groups accompanied by a sample of present-day femurs from the radiology database of CT scans. Data from 243 femoral bones were collected, 50 of which from the fourth century, 26 from the fourteenth century, 68 from the eighteenth century, and 99 femurs from the 20/twenty-first century.

RESULTS

Alpha angles in all historical samples showed pathological values (> 55º) up to a maximum of 11.5% of the cases. Meanwhile, the actual series showed pathological alpha angle in 60.1% of the cases with statistical significant differences.

CONCLUSION

The studied femurs of the western Mediterranean region from the fourth, fourteenth and eighteenth centuries showed pathological alpha angles in a smaller proportion than the actual sample.

LEVEL OF EVIDENCE

Level III, retrospective studies.

Criteria for Return to Play After Hip Arthroscopy in the Treatment of Femoroacetabular Impingement: A Systematic Review

BACKGROUND

Femoroacetabular impingement (FAI) is a common pathology in athletes that often requires operative management in the form of hip arthroscopy.

PURPOSE

To systematically review the rates and level of return to play (RTP) and the criteria used for RTP after hip arthroscopy for FAI in athletes.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

A systematic review of the literature, based on the PRISMA guidelines, was performed using PubMed, Embase, and Scopus databases. Studies reporting outcomes after the use of hip arthroscopy for FAI were included. Outcomes analyzed were RTP rate, RTP level, and criteria used for RTP. Statistical analysis was performed using SPSS software.

RESULTS

Our review found 130 studies, which included 14,069 patients (14,517 hips) and had a mean methodological quality of evidence (MQOE) of 40.4 (range, 5-67). The majority of patients were female (53.7%), the mean patient age was 30.4 years (range, 15-47 years), and the mean follow-up was 29.7 months (range, 6-75 months). A total of 81 studies reported RTP rates, with an overall RTP rate of 85.4% over a mean period of 6.6 months. Additionally, 49 studies reported the rate of RTP at preinjury level as 72.6%. Specific RTP criteria were reported in 97 studies (77.2%), with time being the most commonly reported item, which was reported in 80 studies (69.2%). A total of 45 studies (57.9%) advised RTP at 3 to 6 months after hip arthroscopy.

CONCLUSION

The overall rate of reported RTP was high after hip arthroscopy for FAI. However, more than one-fourth of athletes who returned to sports did not return at their preinjury level. Development of validated rehabilitation criteria for safe return to sports after hip arthroscopy for FAI could potentially improve clinical outcomes while also increasing rates of RTP at preinjury levels.

No linear correlation between pelvic incidence and acetabular orientation: Retrospective observational study

Links between sagittal spinal alignment and acetabular orientation attract considerable research attention with the goal of understanding “hip-spine syndrome.” However, whether pelvic incidence (PI) is related to acetabular orientation remains debatable. The purpose of the present study was to determine: 1. whether the correlation between PI and acetabular orientation is present in pelvises of young healthy adults, and 2. whether the correlation is present in subgroups of sex, or between the left and right pelvis. We analyzed 100 abdominopelvic computed tomography (CT) scans of skeletally healthy young adults. We measured PI and acetabular orientation with three-dimensional (3D) measurements. The orientation of 200 acetabula was measured using 3D reconstructed models of 100 pelvises in the coordinate system based on the anterior pelvic plane (APP). To quantify the acetabular orientation, the radiographic definitions of anteversion and inclination were used. To examine the correlation between acetabular orientation and PI, Pearson's correlation was used. The mean PI was 46.9° ± 10.2°, and the mean acetabular orientation 15.3° ± 5.7° anteverted and 37.5° ± 3.9° inclined. While no significant difference in the PI was observed, the average acetabular orientation of female pelvises (anteversion, 17.5° ± 5.6°; inclination, 36.7° ± 3.7°) was more anteverted and less inclined compared to that of male pelvises (anteversion, 13.2° ± 4.9°; inclination, 38.3° ± 3.9°, respectively; P values < .05). The correlation between PI and acetabular orientation was statistically not significant. After division of study group by sex, the linear correlation between PI and acetabular orientation was not statistically supported. The asymmetry of the acetabular orientation between the left and right sides was not significant. The linear relationship between anatomical acetabular orientation and PI was not evident in the normal population. Our finding thus proves the absence of a linear relationship between the upper and lower articular orientation of the pelvic segment and deepens the understanding of the characteristics of acetabular orientation and PI.

Outcomes of arthroscopic femoroplasty in patients with cam lesions: Minimum 2-year follow-up

PURPOSE

Successful arthroscopic femoroplasty in patients with cam lesions have been reported in Western countries in the last two decades. However, the outcomes after arthroscopic femoroplasty in Asia have thus far only been reported in patients with borderline dysplasia and in the military population. This retrospective study was designed to evaluate the short-term clinical outcomes and radiologic outcomes after hip arthroscopy in patients with cam-type femoroacetabular impingement (FAI) at a minimum postoperative follow-up of 2 years.

METHODS

From January 2013 to December 2016, 204 hip arthroscopy procedures were performed. Of these cases, 62 patients (73 hips) underwent hip arthroscopy for cam-type FAI.

RESULTS

Of the 73 hips, 65 (89.0%) achieved gratified reduction or elimination of preoperative pain. The clinical outcomes showed improvement in scores from before surgery to the last follow-up: 67.1 ± 15.0 to 90.2 ± 6.3 for the modified Harris hip score (p < 0.001), 4.7 ± 2.5 to 7.1 ± 1.4 for the University of California Los Angeles score (p < 0.001), and 7.4 ± 1.9 to 1.8 ± 1.5 for the visual analog scale score (p < 0.001). In radiologic assessments, significant improvement was observed in the alpha angle from a mean 60.9° to 49.5° (p < 0.001) and in the head-neck offset from a mean of 3.3 mm to 6.3 mm (p < 0.001). Of the 73 hips, 65 (89.0%) achieved satisfactory reduction or elimination of preoperative pain. In subgroup analysis for the sufficiency of femoroplasty (alpha angle < 55°), the clinical outcomes were not different between the two groups.

CONCLUSION

Arthroscopic femoroplasty resulted in an 89% satisfaction at the 2-year follow-up. Therefore, hip arthroscopic femoroplasty might be an excellent alternative to open surgery and offers a greater probability of good to excellent results.

Elevated levels of TNF-α, IL-1β and IL-6 in the synovial tissue of patients with labral tear: a comparative study with hip osteoarthritis

BACKGROUND

Labral tear can be the initiating factor in the onset of hip osteoarthritis (HOA). However, the physiopathology of labral tear is not fully understood. Our aim was to compare synovial tissue inflammatory cytokine levels between patients with labral tear and late-stage HOA.

METHODS

Synovial tissue from sites showing the greatest inflammation was harvested from 106 hips from 100 subjects during hip surgery. RNA was extracted, and levels of TNFA, IL1B, IL6 and COX2 mRNA were compared among all patients using real-time PCR. Additionally, we examined whether femoroacetabular impingement (FAI) was associated with elevated levels of inflammatory cytokines in patients with labral tear. To analyze the effects of TNF-α on inflammatory mediators in hip synovial tissue, synovial fibroblasts were extracted from hip synovial tissue of patients with labral tear and late-stage HOA (n = 5 each). Mononuclear cells were extracted from synovial tissue, cultured for 7 days, and stimulated with control or 10 ng/mL human recombinant TNF-α for 1 day. mRNA was extracted from stimulated cells and IL1B, IL6, and COX2 levels were determined using real-time PCR.

RESULTS

TNFA, IL1B, and COX2 expression in synovial tissue were significantly higher in patients with labral tear than late-stage HOA (TNFA, p <  0.001; IL1B, p <  0.001; COX2, p = 0.001). There were no differences in expression between patients with labral tear with and without FAI (TNFA, p = 0.546; IL1B, p = 0.559; IL6, p = 0.599; COX2, p = 0.124). Compared to vehicle control, TNF-α stimulation significantly elevated IL1B, IL6, and COX2 expression in synovial fibroblasts collected from patients with labral tear and late-stage HOA (IL1B, p = 0.043 and p = 0.043; IL6, p = 0.043 and 0.043; COX2, p = 0.043 and p = 0.080, respectively).

CONCLUSIONS

TNFA, IL1B, and COX2 expression were elevated in the synovial tissue of patients with labral tear. Further investigations are needed to reveal the relationship between inflammatory cytokine levels and various aspects of labral tear pathology, including pain and the onset and progression of OA.

Population-based prevalence of femoroacetabular impingement in Japan

OBJECTIVES

The prevalence of femoroacetabular impingement (FAI) was evaluated using a Japanese population-based cohort of participants aged ≥50 years.

METHODS

Radiographs (n = 854) of bilateral hips of 427 participants (279 women, 148 men) were used for the analysis. The prevalence of cam type, pincer type, and mixed type FAI as well as osteoarthritis was evaluated. The association of FAI and osteoarthritis (OA), and pain were also evaluated.

RESULTS

The prevalence of cam type and pincer type FAI were 4.2% and 20.3%, respectively. Mixed type FAI was 0.7%. OA was found in 4.0% of patients, and 17 hips (2.0%) with any FAI also had OA. A significant relationship between cam type FAI and OA was found, whereas no significant relationship between pincer type FAI and OA was seen. Sixty (7.0%) of all the hips were reported to be painful, and 14 of those painful hips (1.6%) had FAI. No significant relationship between FAI and hip pain was found.

CONCLUSION

We reported the first population-based prevalence of FAI in Japan. Radiological FAI was common, and pincer type was more common than cam type. The anatomical abnormalities associated with FAI, although often asymptomatic, are risk factors for OA.

Serial Changes in Image Findings of Herniation Pits from the First Appearance

Backgroud

Herniation pits (HPs) have been considered to be an incidental finding, but recently femoroacetabular impingement (FAI) has been proposed as a possible cause of their formation. The findings on bone scans of HPs are variable in the literature: some showed increased uptake; the majority did not. We hypothesized that serial changes in image findings of HPs would explain the reason for the variable bone scan findings.

Methods

Four patients (5 hips) were followed up for more than 7 years. All patients were women and regularly underwent bone scintigraphy after the diagnosis of breast cancer. Small lesions with increased uptake were first detected on bone scintigraphy at the age of 44 to 64 years. In all cases, the lesions were confirmed by magnetic resonance imaging and follow-up bone scintigrams were taken regularly. Four lesions were also evaluated by computed tomography. Changes in the size of the pits and the intensity of the increased uptake on bone scintigraphy were evaluated.

Results

On the bone scintigrams, the lesions with increased uptake were detected in the femoral neck at 5–20 months after previous negative bone scintigraphy. There had been no events or symptoms associated with the newly detected increased uptake. On follow-up scans, the intensity of the uptake decreased gradually and the areas of increased uptake disappeared completely at 14–50 months after their first appearance. In 3 cases (2 patients), the pit size increased during follow-up.

Conclusions

The areas of increased uptake on bone scintigraphy gradually disappeared in all cases and the increase in pit size was frequent. There was no case in which signs or symptoms suggestive of FAI were noticed.

β-Angles of hips with femoroacetabular impingement versus asymptomatic normal hips in a Japanese population: A CT-based observational clinical study

BACKGROUND

The beta angle (β-angle)-although used to assess femoroacetabular impingement (FAI)-has not been well evaluated. This study aimed to measure the β-angle on multiradial computed tomography (CT) slice images of both hips with symptomatic FAI and asymptomatic normal hips to determine its optimal cutoff value for detecting FAI in a Japanese population.

METHODS

CT was performed with each subject supine. The β-angle was measured on seven radial slices (designated R0, R15, R30, R45, R60, R75, R90) that were generated at 15° intervals from the oblique axial slice through the center of the femoral neck. An a priori power analysis was performed. The measurements were made in 20 FAI hips (FAI group) and 23 asymptomatic normal hips (ANH group). Cutoff values were evaluated using receiver operating characteristic curves.

RESULTS

The mean β-angles of the FAI and ANH groups at R0, R15, R30, R45, R60, R75, and R90° were, respectively, 73.6° and 84.2°, 66.0° and 79.3°, 57.2° and 69.2°, 48.1° and 63.1°, 46.7° and 62.5°, 50.0° and 63.7°, and 53.7° and 65.9°. For all slices, the β-angle was significantly smaller in the FAI group than the ANH group. The optimal β-angle cutoff values for diagnosing FAI at R0, R15, R30, R45, R60, R75, and R90 were 73.9°, 70.2°, 61.4°, 55.7°, 53.6°, 59.4°, and 60.9°, respectively. The respective specificities and sensitivities of the cutoff values at R0, R15, R30, R45, R60, R75, and R90 were 78.3% and 65.0%, 82.6% and 70.0%, 73.9% and 60.0%, 73.9% and 75.0%, 95.7% and 75.0%, 69.6% and 95.0%, and 78.3% and 80.0%.

CONCLUSIONS

In all radial slices, the β-angle was significantly smaller in the hips with symptomatic FAI than in the asymptomatic normal hips. The most useful cutoff value for diagnosing FAI was a β-angle of 53.6° at R60.

Prevalence and morphological features of acetabular dysplasia with coexisting femoroacetabular impingement-related findings in a Japanese population: a computed tomography-based cross-sectional study

The coexistence of acetabular dysplasia (AD) and femoroacetabular impingement (FAI) has not been well discussed. This study was performed to elucidate the prevalence and morphological features of AD with coexisting FAI-related findings in a Japanese population. Computed tomography images were retrospectively evaluated. AD was classified as definite or borderline. The morphological findings that defined cam deformity were an α angle of ≥55°, head–neck offset ratio (HNOR) of <0.13, pistol grip deformity positivity and herniation pit positivity. The morphological findings that defined pincer deformity were acetabular index of ≤0° and a retroverted acetabulum. In total, 128 hips (male, 64; female, 64) were analyzed. The prevalence of coexistence of AD and FAI-related findings was detected in 23.4% of hips (definite AD and FAI, 7.8%; borderline AD and FAI, 15.6%). The percentages of hips with AD containing cam or pincer deformities among all were 54.3% and 4.3%, respectively. The percentage of AD with coexisting cam and that of AD with coexisting combined deformities was significantly higher in men, respectively. On the other hand, the most major morphological feature of FAI detected in hips with AD was a HNOR of <0.13. The coexistence of AD and FAI-related findings was common in a Japanese population, and 65.2% of hips with AD had some FAI-related findings. In discussing and managing AD, we recommend paying attention to the coexistence with FAI-related findings, especially in men and in borderline AD. In such hips, the most notable parameter as a morphological feature of FAI is a reduced HNOR.

Multiplanar evaluation of radiological findings associated with acetabular dysplasia and investigation of its prevalence in an Asian population: a CT-based study

Background

Acetabular dysplasia (AD) is a well-known cause of osteoarthritis (OA) of the hip, with its prevalence previously determined on plain radiography. The prevalence of preexisting AD was reported as 7.3% in a patient-based Asian population. Although computed tomography (CT) could evaluate AD in multiple planes, its prevalence using multiplanar CT images has not been reported. We investigated its prevalence with CT on coronal, axial, and sagittal planes and then determined if adding the axial and sagittal planes enhanced the investigation.

Methods

We retrospectively examined 52 consecutive Japanese individuals (mean age 59.4 years) who had undergone CT for conditions unrelated to hip disorders. The inclusion criteria of CT images were (1) reconstructed axial slice thickness of ≤1 mm and (2) normal pelvic rotations and tilt. Exclusion criteria were (1) age <20 years, (2) neither hip center could be clearly detected, (3) evidence of hip OA. The parameters used to define AD on the coronal plane were the center–edge angle, Sharp angle, acetabular index, acetabular depth ratio, and acetabulum head index. The anterior and posterior acetabular sector angles were used as axial parameters and the vertical-center-anterior margin angle as the sagittal parameter. AD prevalence was calculated using multiplanar images and then compared with the previously reported Asian prevalence using 95% confidence intervals (CI). In this study, we defined “prevalence” as the proportion of subjects who had AD in at least one hip.

Results

The mean prevalence of AD on coronal, axial, and sagittal planes was 16.9, 15.4, and 7.7%, respectively. The lowest prevalence found by combining the three planes was 25.0% (95% CI 15.2–38.2%). This prevalence was significantly higher than that in the previously reported Asian population (7.3%).

Conclusions

At the lowest estimate, the prevalence of AD evaluated in three planes was more than twice as high as the previously reported prevalence in Asians when we investigated its prevalence using multiplanar images. The prevalence of AD in the axial and sagittal planes was not negligible. We therefore suggest that it is important to add axial and sagittal planes’ data when investigating the prevalence of AD.