The prevalence of femoroacetabular impingement in radiographs of asymptomatic subjects: a cross-sectional study

Deletion of Trps1 regulatory elements recapitulates postnatal hip joint abnormalities and growth retardation of Trichorhinophalangeal syndrome in mice

Trichorhinophalangeal syndrome (TRPS) is a genetic disorder caused by point mutations or deletions in the gene-encoding transcription factor TRPS1. TRPS patients display a range of skeletal dysplasias, including reduced jaw size, short stature, and a cone-shaped digit epiphysis. Certain TRPS patients experience early onset coxarthrosis that leads to a devastating drop in their daily activities. The etiologies of congenital skeletal abnormalities of TRPS were revealed through the analysis of Trps1 mutant mouse strains. However, early postnatal lethality in Trps1 knockout mice has hampered the study of postnatal TRPS pathology. Here, through epigenomic analysis we identified two previously uncharacterized candidate gene regulatory regions in the first intron of Trps1. We deleted these regions, either individually or simultaneously, and examined their effects on skeletal morphogenesis. Animals that were deleted individually for either region displayed only modest phenotypes. In contrast, the Trps1Δint/Δint mouse strain with simultaneous deletion of both genomic regions exhibit postnatal growth retardation. This strain displayed delayed secondary ossification center formation in the long bones and misshaped hip joint development that resulted in acetabular dysplasia. Reducing one allele of the Trps1 gene in Trps1Δint mice resulted in medial patellar dislocation that has been observed in some patients with TRPS. Our novel Trps1 hypomorphic strain recapitulates many postnatal pathologies observed in human TRPS patients, thus positioning this strain as a useful animal model to study postnatal TRPS pathogenesis. Our observations also suggest that Trps1 gene expression is regulated through several regulatory elements, thus guaranteeing robust expression maintenance in skeletal cells.

Does Femoral Osteoplasty Improve Long-term Clinical Outcomes and Survivorship of Hip Arthroscopy? A 15-Year Minimum Follow-up Study

BACKGROUND

Although femoral osteoplasty is common practice in treating cam-type femoroacetabular impingement (FAI), long-term data are lacking that support the ability of this procedure to optimize outcomes and alter natural history.

PURPOSE

To compare long-term clinical outcomes and survivorship of treatment for symptomatic FAI via arthroscopic correction of labral or chondral pathology with and without femoral osteoplasty.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A retrospective cohort study was performed across 2 consecutive cohorts of patients with isolated cam-type FAI who underwent hip arthroscopic treatment of labral or chondral pathology without femoral osteoplasty (HS group) or with femoral osteoplasty (HS-OST group). These unique cohorts were established at a distinct transition time in our practice before and after adoption of femoral osteoplasty for treatment of FAI. Clinical outcomes were measured using the modified Harris Hip Score (mHHS). Kaplan-Meier analysis was used to assess for total hip arthroplasty (THA)-free and reoperation-free survivorship.

RESULTS

The final HS group included 17 hips followed for 19.7 ± 1.2 years, and the final HS-OST group included 23 hips followed for 16.0 ± 0.6 years. No significant patient or morphological differences were found between groups. Compared with the HS group, the HS-OST group had significantly higher final mHHS (82.7 vs 64.7 for HS-OST vs HS, respectively; P = .002) and mHHS improvement (18.4 vs 6.1; P = .02). The HS-OST group also had significantly greater 15-year THA-free survivorship versus the HS group (78% vs 41%, respectively; P = .02) and reoperation-free survivorship (78% vs 29%; P = .003).

CONCLUSION

This study demonstrated superior long-term clinical outcomes and survivorship with combined arthroscopy and femoral osteoplasty compared with hip arthroscopy alone. These long-term data strongly support the practice of femoral osteoplasty in patients with cam FAI morphologies and suggest that this treatment alters the natural history of FAI at long-term follow-up.

Hip Preservation Surgery in Osteoarthritis Prevention: Potential Benefits of the Radiographic Angular Correction

Objective: The aim of the study is to describe the morphology associated with the development of osteoarthritis (OA) in three different age groups. These data will contribute to defining the morphology associated with early and late hip OA. Methods: We studied 400 hips in 377 patients who had undergone primary THA due to idiopathic OA. Three groups were compared: group 1 (n = 147), younger patients, aged up to 60 years; group 2 (n = 155), patients aged between 61 and 74 years; and group 3 (n = 98), aged 75 or over. Five independent researchers measured the hip angles and the mean values were used to build a database. Results: No differences between groups in sex distribution and BMI were detected. Less coverage of the head (extrusion index), higher Tönnis angle, lower Wiberg and alpha angles characterized early OA hips. These differences increased with age, being greater between group 2 and group 3 (p < 0.01). However, significant differences were still present in the comparison between group 1 and group 2 (p < 0.01)). No differences were detected between group 2 and group 3. Conclusion: Elevated acetabular angle, head extrusion and decreased Wiberg angle characterize hip osteoarthritis at younger ages and should be the focus of hip preservation surgery in terms of osteoarthritis prevention. Pincer-type FAI (higher Wiberg and lower Tönnis angle) and higher alpha angle (CAM) are correlated with the development of later OA. These results shed doubt on applying the hip preservation surgery concept in terms of osteoarthritis prevention in FAI, especially in Pincer-type FAI patients.

Hip joint motion does not change one year after arthroscopic osteochondroplasty in patients with femoroacetabular impingement evaluated with dynamic radiostereometry

Purpose

Dynamic radiostereometric analysis (dRSA) enables precise non-invasive three-dimensional motion-tracking of bones for assessment of joint kinematics. Hereby, the biomechanical effects of arthroscopic osteochondroplasty of the hip (ACH) can be evaluated in patients with femoroacetabular impingement (FAI).

The aim was to investigate the pre- and postoperative range of motion (ROM) and the CT bone volume removed (BV) after ACH. We hypothesize increase in ROM 1 year after surgery.

Methods

Thirteen patients (6 female) with symptomatic FAI were included prospectively. The patient’s hips were CT-scanned and CT-bone models were created. Preoperative dRSA recordings were acquired during passive flexion to 90°, adduction, and internal rotation (FADIR). ACH was performed, CT and dRSA were repeated 3 months and 1 year postoperatively. Hip joint kinematics before, and 3 months and 1 year after ACH were compared pairwise. The bone volume removal was quantified and compared to change in ROM.

Results

Mean hip internal rotation, adduction and flexion were all unchanged after ACH at 1-year follow-up (p > 0.84). HAGOS scores revealed improvement of quality of life (QOL) from 32 to 60 (p = 0.02). The BV was between 406 and 1783 mm³ and did not correlate to post-operative ROM.

Conclusions

ACH surgery in FAI patients had no impact of ROM at 1-year follow-up. QOL improved significantly. This indicates that the positive clinical effects reported after ACH might be a result of reduced labral stress and cartilage pressure during end-range motion rather than increased ROM.

Level of evidence

Therapeutic prospective cohort study, level II.

Prevalence of Radiographic Signs of Pincer Deformities in Asymptomatic Indian Individuals: A Retrospective Analysis

OBJECTIVE

Femoroacetabular impingement (FAI) is the result of abnormal contact between the proximal femur and the acetabulum rim. Pincer impingement is the result of a globally deep acetabulum, focal anterior overcoverage or less commonly posterior overcoverage. The presence of radiological signs of femoroacetabular impingement (FAI) is not necessarily associated with symptoms. The study aims to find the prevalence of such signs in asymptomatic adult individuals.

METHODS

Data of 714 patients (1428 hips) who have undergone PBH-AP (Pelvis Both hip- Anterior-Posterior view) radiograph for conditions unrelated to the disorders of the hip were taken for study. We evaluated the images for the presence of a cross-over sign (COS) and ischial spine sign (ISS) and measured Lateral Central-Edge (LCE) angle (Wiberg) and Tonnis angle (TA).

RESULTS

Mean age was 33.4 ± 9.8 years. Positive cross-over signs and ischial spine signs were seen in 26.6% and 13.9%, respectively; LCE angle > 40° in 25.5% and Tonnis angle ≤ 0° in 13.5% patients. 36.7% of patients showed atleast one radiological sign of acetabulum overcoverage. There was a significant difference in means of the values of LCE angle and Tonnis angle between males and females (2.9 and - 1.2, respectively). There was no significant difference in prevalence of COS and ISS among the two genders.

CONCLUSION

This study shows that there is higher prevalence of radiographic signs (36.7%) of pincer deformity among asymptomatic adults. Therefore, new clinical studies are required to clarify the actual significance of these findings.

No Association Between Intrauterine Contraceptive Devices and Musculoskeletal Hip Joint Pain

Purpose

To investigate the association between intrauterine device (IUD) use and hip pain, orthopaedic visits for hip pain, and arthroscopic hip surgery.

Methods

This was a retrospective cohort study of patients aged 18-44 years old using either IUDs or subdermal implants for contraception in a large commercial claims database (MarketScan) from 2012 to 2015. All patients had at least 12 months of continuous enrollment both before and after contraceptive placement. Patients with a history of hip pain or surgery were excluded. The primary outcome was new hip pain. Secondary outcomes included visiting an orthopaedic or sports medicine provider for a hip complaint, intra-articular hip injection, and arthroscopic hip surgery. Outcomes were analyzed with Cox proportional-hazard models.

Results

We identified a total of 242,383 patients, including 216,541 (89.3%) with IUDs and 25,842 (10.7%) with subdermal contraceptive implants. In time-to-event analysis, IUDs (vs implants) were not associated with increased risk of new hip pain diagnoses (hazard ratio [HR] 0.95, 95% confidence interval [CI] 0.87-1.03, P = .21). In contrast, both age (P < .001) and region (P < .001) were associated with increased risk of new hip pain. Similar results were seen for the secondary outcomes, including risk of orthopaedic visits for hip complaints (HR 1.06, 95% CI 0.83-1.35, P = .63), intra-articular injections of the hip (HR 0.94, 95% CI 0.63-1.41, P = .77), and hip arthroscopy procedures (HR 1.13, 95% CI 0.53-2.40, P = .75).

Conclusions

In this study, we found no evidence that IUDs were associated with hip pain or surgery.

Level of Evidence

Level III, retrospective cohort.

Prevalence of Morphological Variations Associated With Femoroacetabular Impingement According to Age and Sex: A Study of 1878 Asymptomatic Hips in Nonprofessional Athletes

Background:

Radiographic findings related to the cam and pincer variants of femoroacetabular impingement (FAI) include measurements of the alpha angle and lateral center-edge angle (LCEA). The function of these radiographic findings has been put into question because of high heterogeneity in reported studies.

Purpose:

The aim of this study was 3-fold: (1) to determine the prevalence of cam and pincer variants according to sex and age on anteroposterior (AP) pelvic radiographs from an asymptomatic nonathletic population, (2) to identify the most common radiographic signs of cam- and pincer-type variants, and (3) to determine if there are variations in the prevalence of these radiographic signs according to sex and age.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

There were 3 independent observers who retrospectively analyzed the 939 AP pelvic radiographs (1878 hips) of patients aged 18 to 50 years who did not have hip symptoms and who were not professional athletes. The prevalence of the cam and pincer variants according to the alpha angle and LCEA, respectively, and the presence of other radiographic signs commonly associated with these variables were determined in the overall population and by subgroup according to sex and age group (18-30, 31-40, and 41-50 years). Descriptive and inferential statistics were used to analyze the study sample.

Results:

The mean age of the included population was 31.0 ± 9.2 years, and 68.2% were male. The prevalence of the cam-type variant was 29.7% (558/1878), and that of the pincer-type variant was 24.3% (456/1878). The radiographic signs that were most associated with the cam and pincer variants were a pistol-grip deformity and the crossover sign, respectively. Significant differences (P < .001) in the prevalence of these variants were identified between men and women in both variants. No differences were observed in the alpha angle or LCEA according to sex or age.

Conclusion:

Radiographic findings suggestive of FAI had significant variations with respect to sex and age in this study sample. This study provides information to determine the prevalence of these anatomic variants in the general population.

Radiographic Indices Are Not Predictive of Clinical Outcomes Among 1735 Patients Indicated for Hip Arthroscopic Surgery: A Machine Learning Analysis

BACKGROUND

The relationship between the preoperative radiographic indices for femoroacetabular impingement syndrome (FAIS) and postoperative patient-reported outcome measure (PROM) scores continues to be under investigation, with inconsistent findings reported.

PURPOSE

To apply a machine learning model to determine which preoperative radiographic indices, if any, among patients indicated for the arthroscopic correction of FAIS predict whether a patient will achieve the minimal clinically important difference (MCID) for 1- and 2-year PROM scores.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 1735 consecutive patients undergoing primary hip arthroscopic surgery for FAIS were included from an institutional hip preservation registry. Patients underwent preoperative computed tomography of the hip, from which the following radiographic indices were calculated by a musculoskeletal radiologist: alpha angle, beta angle, sagittal center-edge angle, coronal center-edge angle, neck shaft angle, acetabular version angle, and femoral version angle. PROM scores were collected preoperatively, at 1 year postoperatively, and at 2 years postoperatively for the modified Harris Hip Score (mHHS), the Hip Outcome Score (HOS)-Activities of Daily Living (HOS-ADL) and -Sport Specific (HOS-SS), and the International Hip Outcome Tool (iHOT-33). Random forest models were created for each PROM at 1 and 2 years' follow-up, with each PROM's MCID used to establish clinical meaningfulness. Data inputted into the models included ethnicity, laterality, sex, age, body mass index, and radiographic indices. Comprehensive and separate models were built specifically to assess the association of the alpha angle, femoral version angle, coronal center-edge angle, McKibbin index, and hip impingement index with respect to each PROM.

RESULTS

As evidenced by poor area under the curves and P values >.05 for each model created, no combination of radiographic indices or isolated index (alpha angle, coronal center-edge angle, femoral version angle, McKibbin index, hip impingement index) was a significant predictor of a clinically meaningful improvement in scores on the mHHS, HOS-ADL, HOS-SS, or iHOT-33. The mean difference between 1- and 2-year PROM scores compared with preoperative values exceeded the respective MCIDs for the cohort.

CONCLUSION

In patients appropriately indicated for FAIS corrective surgery, clinical improvements can be achieved, regardless of preoperative radiographic indices, such as the femoral version angle, coronal center-edge angle, and alpha angle. No specific radiographic parameter or combination of indices was found to be predictive of reaching the MCID for any of the 4 studied hip-specific PROMs at either 1 or 2 years' follow-up.

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.

Prevalence of radiographic parameters on CT associated with femoroacetabular impingement in a Chinese asymptomatic population

BACKGROUND

Imaging evaluation of femoroacetabular impingement (FAI) plays a major role in early diagnosis and treatment, preventing irreversible degenerative changes in hip joints.

PURPOSE

To investigate the anatomical parameters associated with FAI in a Chinese asymptomatic population by computed tomography (CT) and to evaluate the prevalence of the radiographic features of cam and pincer types in Chinese patients.

MATERIAL AND METHODS

We reviewed the CT images of 470 hips in 235 Chinese patients who underwent abdominal and pelvic CT scans for reasons unrelated to hip symptoms at our hospital between February and October 2017. The following measurements were made on each hip joint: acetabular version angle (AV); anterior acetabular sector angle (AASA); posterior acetabular sector angle (PASA); the lateral center edge angle (LCE); the alpha angle (AA); and femoral head-neck offset (FHNO).

RESULTS

Significant differences in all parameters were seen between men and women. Young men and elderly women showed more retroversion in our study. LCE, AA, and FHNO were all larger in men than women. The data showed 25% of female joints and 34.5% of male joints had at least one predisposing factor for FAI using measurement parameters by CT images in Chinese asymptomatic patients, and the prevalence of pincer lesion (19.1%) was larger than cam lesion (9.1%).

CONCLUSION

Morphological features associated with FAI are also present in Chinese asymptomatic patients. The threshold values for abnormal parameters should be reconsidered based on gender, age, and other factors in order to improve the accuracy of diagnosis.

How Useful Is the Flexion-Adduction-Internal Rotation Test for Diagnosing Femoroacetabular Impingement: A Systematic Review

OBJECTIVE

Clinicians use the flexion, adduction, and internal rotation (FADIR) test in the diagnosis of femoroacetabular impingement (FAI). However, the diagnostic utility of this test remains unclear. The purpose of this review was to determine the utility of the FADIR test in diagnosing FAI.

DATA SOURCES

MEDLINE, EMBASE, and PubMed were searched using relevant key terms and study screening was performed in duplicate. Patient demographics, diagnostic imaging, and summary measures (eg sensitivity, specificity, etc.) of the FADIR test in patients with FAI were recorded.

MAIN RESULTS

Eight studies of levels III (87.5%) and IV (12.5%) evidence were included. Four hundred fifty-two patients (622 hips) with a mean age of 27.0 ± 9.0 were examined. Alpha (75.1%) and/or center-edge (26.8%) angles were used to diagnose hips with FAI. X-ray (78.9%), magnetic resonance imaging (MRI) (16.2%), and computed tomography (CT) (4.8%) were used to confirm the diagnosis of FAI. The sensitivity when confirmed by x-ray, MRI, or CT was 0.08 to 1, 0.33 to 1 and 0.90, respectively. The specificity when confirmed by x-ray and MRI was 0.11 and 1, respectively.

CONCLUSIONS

Although the overall utility of the FADIR test in diagnosing FAI remains unclear given its moderate sensitivity and specificity, it may be a useful screening tool for FAI because of its low risk. Clinicians should consider the variability in sensitivity and specificity values reported and the low quality of literature available. Future studies should use large sample sizes and consistent radiographic measurements to better understand the usefulness of this physical examination maneuver in diagnosing FAI.

LEVEL OF EVIDENCE

Level IV, Systematic Review of Level III and IV studies.

THE ROLE of a BIKE FIT in CYCLISTS with HIP PAIN. A CLINICAL COMMENTARY

Hip pathology is common amongst athletes and the general population. The mechanics of cycling have the potential to exacerbate symptomatic hip pathology and progress articular pathology in patients with morphologic risk factors such as femoroacetabular impingement. A professional fit of the bicycle to the individual which aims to optimize hip joint function can allow patients with hip pathology to exercise in comfort when alternative high impact exercise such as running may not be possible. Conversely improper fit of the bicycle can lead to hip symptoms in otherwise healthy individuals who present with risk factors for hip pain. Accordingly a bike fit can form part of the overall management strategy in a cyclist with hip symptoms. The purpose of this clinical commentary is to discuss hip pathomechanics with respect to cycling, bicycle fitting methodology and the options available to a physical therapist to optimize hip mechanics during the pedaling action.

Prevalence of Radiographic Signs of Femoroacetabular Impingement in Asymptomatic Patients and Non-Athletes

Objective

Femoroacetabular impingement has been described as an anatomical variation of the proximal femur and/or acetabular rim, impinging the hip joint. A portion of the population asymptomatic in the hip may present radiographic changes from femoroacetabular impingement. The aim of the present study was to evaluate the prevalence of these signs in asymptomatic and sedentary males.

Methods

This was a clinical, observational, primary, cross-sectional, controlled study. A total of 32 male volunteers aged between 18 and 40 years, asymptomatic in the hip and sedentary, were selected from a university hospital orthopedic emergency room. All patients underwent standard anteroposterior pelvic radiographs. The measurements of the alpha angle, the retroversion index, the ischial spine signal, and the posterior wall sign were analyzed.

Results

The mean age was 29 years (18-40 years old). The prevalence of radiographic signs of femoroacetabular impingement using an alpha angle of 67 ^o was of 53.1%; with an alpha angle of 82 ^o , it was of 31.2%. The mean alpha angle was 67 ^o (52.4-88.2 ^o ), with 35.9% of the hips classified as borderline and 6.3% as pathological. The mean alpha angle for the right side was 67.5 ^o (52.5-88.2 ^o ), and, for the left, it was 66.6 ^o (53.1-86.9 ^o ). The mean retroversion index was 0.048 (right side: 0.044; left side: 0.052). The spine signal was positive in 15.6%, and the posterior wall sign, in 20.3% of the cases.

Conclusion

This study showed that the prevalence of radiographic signs in a population of asymptomatic and sedentary adult men was high (31.2%). New studies are required to explian the actual clinical significance of this finding.

Increased Prevalence of Femoroacetabular Impingement in Patients With Proximal Hamstring Tendon Injuries

PURPOSE

To determine the prevalence of clinically diagnosed femoroacetabular impingement (FAI) in a consecutive series of patients presenting with proximal hamstring tendon injury and to correlate this with pelvic anatomic factors.

METHODS

The prevalence of clinically symptomatic cam-, pincer-, and mixed-type and overall FAI was calculated among a consecutive series of patients presenting to a hip preservation clinic with a confirmed clinical and radiographic diagnosis of proximal hamstring tendon injury between 2012 and 2017. The presence of a cam lesion was determined by an alpha angle > 50° on radiographs and computed tomography radial sequences of the head-neck junction and a femoral head-neck offset ratio < 0.18. Clinical diagnoses of osseous impingement were determined according to accepted pathomorphologic signs and measurements. A diagnosis of FAI was confirmed by imaging findings of acetabular overcoverage for pincer-type FAI and the presence of an anterior or lateral cam lesion for cam-type FAI.

RESULTS

Overall, 120 hips in 97 patients (mean age, 45 years) were included in this study. A clinical diagnosis of FAI was noted in 70.8% of hips (pincer-type 9.2%, cam-type 40.8%, mixed-type 20.8%), an approximate 2- to 7-fold increased prevalence in comparison with the general population from prior studies.

CONCLUSIONS

The prevalence of FAI is high in patients with symptomatic proximal hamstring tendon pathology. Because FAI results in restriction of hip range of motion and altered pelvic tilt, future studies are warranted to investigate whether the presence of FAI acts as a predisposing factor for injury to the hamstring muscle complex.

LEVEL OF EVIDENCE

Level IV, case series.

Relationship between crossover sign and anterior center-edge angle

Purpose

The aim of this study was to evaluate the relationship between the anterior center-edge angle (ACEA) and lateral center-edge angle (LCEA) and crossover ratio.

Methods

Consecutive patients presenting for evaluation of hip pain were reviewed. The following measurements were recorded and analyzed: Crossover ratio, LCEA, ACEA, and alpha-angle.

Results

68 patients met inclusion criteria. The only statistically significant radiographic measurement when stratified by gender was alpha angle (P < 0.001). There was moderate correlation between crossover ratio and ACEA and LCEA with coefficients of -0.48 and -0.48, respectively.

Conclusion

A correlation exists between crossover ratio and ACEA and LCEA.

The Importance of Comprehensive Cam Correction: Radiographic Parameters Are Predictive of Patient-Reported Outcome Measures at 2 Years After Hip Arthroscopy

BACKGROUND

The specific influence of preoperative and postoperative radiographic measurements on patient-reported outcome measures after hip arthroscopy for femoroacetabular impingement (FAI) remains unclear.

PURPOSE

To investigate the relationship between radiographic measurements and 2-year outcomes after hip arthroscopy for the treatment of FAI.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A clinical registry of patients undergoing primary hip arthroscopy for FAI between January 1, 2012, and December 31, 2014, was queried. Outcome measures included the Hip Outcome Score (HOS) Activities of Daily Living (ADL), HOS Sport-Specific Subscale (SSS), modified Harris Hip Score (mHHS), and visual analog scale (VAS) for pain and satisfaction. Preoperative and postoperative radiographic measurements were recorded. Univariate analysis was conducted to identify relationships between all radiographic and demographic variables and outcome scores. A multivariate regression analysis, controlling for demographic factors, was used to identify independent associations between radiographic measurements on plain radiographs and patient-reported outcomes.

RESULTS

The authors identified 707 patients who underwent primary hip arthroscopic management for FAI who were included for analysis. Two-year outcome surveys were completed for 78% to 84% of patients. The mean age of the patients was 33.2 ± 12.3 years, and 64.4% of the patients (n = 456) were female. The mean anteroposterior (AP) alpha angle decreased by 34.3° ( P < .0001), false profile alpha angle by 25.2° ( P < .0001), Dunn lateral alpha angle by 28.9° ( P < .0001), lateral center edge angle by 2.6° ( P < .0001), and anterior center edge angle by 3.4° ( P < .0001). The HOS-ADL score increased from 65.7 ± 18.7 preoperatively to 85.9 ± 16.7 postoperatively ( P < .0001), HOS-SSS increased from 43.4 ± 23.1 to 72.6 ± 27.2 ( P < .0001), and mHHS increased from 57.7 ± 14.0 to 79.1 ± 17.2 ( P < .0001). With multivariate analysis, independent predictors of the postoperative HOS-ADL score included the preoperative false profile alpha angle (beta = -0.16, P = .028). Independent predictors of HOS-SSS score were preoperative AP alpha angle (beta = -0.33, P = .032) and preoperative false profile alpha angle (beta = -0.28, P = .041). For the postoperative mHHS score, independent predictors included preoperative AP alpha angle (beta = -0.18, P = .046), preoperative false profile alpha angle (beta = -0.20, P = .014), and postoperative false profile alpha angle (beta = -0.48, P = .035). The preoperative AP alpha angle (beta = 0.28, P = .024) was a significant predictor for the postoperative VAS pain score. The preoperative false profile alpha angle (beta = -0.34, P = .040) was a significant predictor for the postoperative VAS satisfaction score.

CONCLUSION

The authors observed that radiographic measurements, specifically the preoperative false profile alpha angle, AP alpha angle, and postoperative false profile alpha angle, are independent predictors of 2-year clinical outcomes. The femoral-side measurements were the strongest independent predictors of outcomes, especially measurements of the anterior and lateral-based CAM lesion.

Prevalence of asymptomatic femoroacetabular impingement in Turkey; cross sectional study

OBJECTIVES

Femoroacetabular impingement (FAI) is one of the causes of hip pain in young-adult patients. The purpose of our study is to determine the prevalence of radiological FAI findings in asymptomatic population in Turkey.

METHODS

Trauma patients aged 18-65 years who applied to the emergency service between September 2015 and September 2016 were retrospectively evaluated for this study. After a preliminary study and power analysis, 2152 hips of the 1076 previously asymptomatic patients were evaluated radiologically with pelvis antero-posterior and frog-leg radiographs. On radiographs of these patients; alpha angle, lateral central edge angle (LCEA), Tönnis angle (TA) and collodiaphyseal angle were measured. Alpha angle values higher than 55° were noted as cam type FAI. TA values lower than 0° or LCEA values higher than 39° were noted as pincer type FAI. LCEA values lower than 25° or TA values higher than 10° were noted as acetabular dysplasia.

RESULTS

Mean age of 1076 patients (602 female, 474 male) was 42.1 ± 15.6 years. The assessment showed that 15.9% of the patients had cam type, 10.6% had pincer type, 3.1% had combined type FAI and 9.3% had findings of acetabular dysplasia. The prevalence of asymptomatic FAI is significantly more in males (46%) in comparison to females (17%) in Turkey.

CONCLUSION

Even though FAI is considered to be a pathology associated with hip osteoarthritis; it is very common in asymptomatic population. In this respect, our study showed that prevalence of radiological FAI findings in asymptomatic adult population was 29.6% in Turkey.

Population-based prevalence of multiple radiographically-defined hip morphologies: the Johnston County Osteoarthritis Project

OBJECTIVE

To provide the first prevalence estimates of different radiographic hip morphologies relevant to dysplasia and femoroacetabular impingement in a well-characterized USA population-based cohort.

METHODS

Cross-sectional data were from the baseline examination (1991-1997) of a large population-based prospective longitudinal cohort study (The Johnston County Osteoarthritis Project). HipMorf software (Oxford, UK) was used to assess hip morphology on anteroposterior (AP) pelvis radiographs. Weighted, sex-stratified prevalence estimates and 95% confidence intervals for four key hip morphologies (AP alpha angle, triangular index sign, lateral center edge angle (LCEA), and protrusio acetabula) were derived and further stratified by age, race and body mass index (BMI).

RESULTS

A total of 5192 hips from 2596 individuals were included (31% African American, 43% male, mean age 63 years, mean BMI 29 kg/m²). Cam morphology was seen in more than 25% of men and 10% of women. Mild dysplasia was present in about 1/3 of men and women, while pincer morphology was identified in 7% of men and 10% of women. Femoral side (cam) morphologies were more common and more frequently bilateral among men, while pincer morphologies were more common in women; mixed morphologies were infrequent. African-Americans were more likely to have protrusio acetabula than whites.

CONCLUSION

We report the first population-based prevalence estimates of radiographic hip morphologies relevant to femoroacetabular impingement (FAI) and dysplasia in the USA. These morphologies are very common, with ¼ men and 1/10 women having cam morphology, 1/3 of all adults having mild dysplasia, and 1/15 men and 1/10 women having pincer morphology in at least one hip.

Prevalence of Cam and Pincer Deformities in the X-Rays of Asymptomatic Individuals

Objective

The presence of radiological signs of femoroacetabular impingement (FAI) is not necessarily associated with symptoms. Hence, the prevalence of cam and pincer deformities in the overall population may be underestimated. The purpose of this study was to screen an unselected cohort of people without hip symptoms for native radiological signs of cam and pincer deformities to determine their actual prevalence.

Materials and Methods

110 asymptomatic patients had AP pelvis X-rays and cross-table hip X-rays performed. We evaluated the images for the presence of cross-over signs and measured lateral center edge (LCE) angles, alpha angles (α-angles), and femoral offset ratios.

Results

Positive cross-over signs were seen in 34%; LCE angles > 40° in 13%; and femoral offset ratios < 0.18 in 43%. In 41% of the patients, α-angles were >50°. Male patients showed significantly higher α-angles, lower offset ratios, and a higher prevalence of cross-over signs. In contrast, female patients had significantly higher LCE angles.

Conclusion

According to our data, radiological signs of cam and pincer deformities are common in asymptomatic people. In clinical practice, patients presenting with hip pain and radiological signs of FAI should undergo further diagnostic evaluation. However, in asymptomatic patients, no further evaluation is recommended.

Dynamic radiostereometric analysis for evaluation of hip joint pathomechanics

BACKGROUND

Dynamic RSA (dRSA) enables non-invasive 3D motion-tracking of bones and may be used to evaluate in-vivo hip joint kinematics including hip pathomechanics such as femoroacetabular impingement (FAI) and the biomechanical effects of arthroscopic cheilectomy and -rim trimming (ACH). The study aim was to evaluate the kinematic changes in the hip joint after ACH.

METHODS

Seven non-FAI affected human cadaveric hips were CT-scanned and CT-bone models were created. dRSA recordings of the hip joints were acquired at five frames/s during passive flexion, adduction to stop, and internal rotation to stop (FADIR). ACH was performed and dRSA was repeated. dRSA images were analyzed using model-based RSA. Hip joint kinematics before and after ACH were compared pairwise. The volume of removed bone was quantified and compared to the postoperative range of motion (ROM).

RESULTS

Mean hip internal rotation increased from 19.1 to 21.9° (p = 0.04, Δ2.8°, SD 2.7) after ACH surgery. Mean adduction of 3.9° before and 2.7° after ACH surgery was unchanged (p = 0.48, Δ-1.2°; SD 4.3). Mean flexion angles during dRSA tests were 82.4° before and 80.8° after ACH surgery, which were similar (p = 0.18, Δ-1.6°, SD = 2.7). No correlation between volume of removed bone and ROM was observed.

CONCLUSIONS

A small increase in internal rotation, but not in adduction, was observed after arthroscopic cheilectomy and -rim trimming in cadaver hips. The hip flexion angle of the FADIR test was reproducible. dRSA kinematic analysis is a new and clinically applicable method with good potential to evaluate hip joint kinematics and to test FAI pathomechanics and other surgical corrections of the hip.

What is the Prevalence of Radiographic Hip Findings Associated With Femoroacetabular Impingement in Asymptomatic Asian Volunteers?

BACKGROUND

Morphologic features of the proximal femur reminiscent of those seen in patients with femoroacetabular impingement (FAI) have been reported among asymptomatic individuals in Western populations, but whether this is the case in Asian populations is unknown.

QUESTIONS/PURPOSES

The purpose of this study was to determine the prevalence of radiographic findings in the proximal femur that are consistent with FAI in asymptomatic Korean volunteers.

METHODS

Two hundred asymptomatic volunteers with no prior hip surgery or childhood hip problems underwent three-view plain radiographs (pelvis AP view, Sugioka view, and 45° Dunn view) of both hips. There were 146 hips from male volunteers and 254 hips from female volunteers in the study. The mean age of all participants was 34.7 years (range, 21-49 years). Cam-type morphologic features were defined as the presence of the following on one or more of the three views: pistol-grip morphologic features, an osseous bump at the femoral head-neck junction, flattening of the femoral head-neck offset, or alpha angle greater than 55°. Pincer-type morphologic features were determined by radiographic signs, including crossover sign, deficient posterior wall sign, or lateral center-edge angle greater than 40°.

RESULTS

The prevalence of cam-type morphologic features seen on at least one radiograph was 38% (male, 57%; female, 26%). The prevalence of cam-type features (at least one positive cam-type feature) was 2.0% (male, 6%; female, 0%) on the pelvic AP view, 24% (male, 36%; female, 17%) on the Sugioka view, and 30% (male, 47%; female, 20%) on the 45° Dunn view. The prevalence of pincer-type morphologic features (at least one positive pincer-type feature) was 23% (male, 27%; female, 21%) on the pelvic AP view.

CONCLUSION

The prevalence of FAI-related morphologic features in asymptomatic Asian populations was comparable to the prevalence in Western populations. Considering the high prevalence of radiographic hip findings reminiscent of FAI in asymptomatic Asian populations, it will be important to determine whether FAI-related morphologic features are a cause of hip pain when considering surgery in Asian patients.

A retrospective analysis on the correlation between hip pain, physical examination findings, and alpha angle on MR images

BACKGROUND

We aimed to search whether alpha angle, a radiological clue used in the diagnosis of femoroacetabular impingement, is correlated with the presence of hip pain, internal rotation angle, and impingement test results on hip impingement patients (CAM type).

METHODS

Medical records of 334 patients (156 women, 178 men) with an average age of 33.8 ± 8.4 (range 20-50) years were retrospectively studied for the alpha angle of the hip measured on magnetic resonance images (MRI). Hip pain and internal rotation angles as well as results of impingement tests were reviewed.

RESULTS

Hip pain was reported more frequently on the right side (n = 35, 10.5%) compared to the left side (n = 22, 6.6%) (p = 0.047). No difference was observed between the right and left sides regarding alpha angles (p = 0.145), internal rotation angles (p = 0.637), or positivity of impingement test (p = 0.210). Internal rotation angles were significantly higher in cases without hip pain (p < 0.001) and in patients with negative impingement test result (p < 0.001). Internal rotation angle correlated positively with age and negatively with the alpha angle. Alpha angle was increased in cases that report pain, those with an internal rotation angle <20°, or cases with positive impingement test. The pain was more common, internal rotation angle was higher, and positivity for impingement was more frequent if the alpha angle was <55°. Patients with hip pain or positive impingement test or internal rotation angle <20° had increased alpha angles (p < 0.001).

CONCLUSIONS

The pain, impingement test results, and internal rotation angle seem to be associated with alpha angle of the hip measured on MRI in hip impingement patients.

Prevalence of cam hip shape morphology: a systematic review

OBJECTIVE

Cam hip shape morphology is a recognised cause of femoroacetabular impingement (FAI) and is associated with hip osteoarthritis. Our aim was to systematically review the available epidemiological evidence assessing the prevalence of cam hip shape morphology in the general population and any studied subgroups including subjects with and without hip pain.

DESIGN

All studies that reported the prevalence of cam morphology, measured by alpha angles, in subjects aged 18 and over, irrespective of study population or presence of hip symptoms were considered for inclusion. We searched AMED, MEDLINE, EMBASE, CINAHL and CENTRAL in October 2015. Two authors independently identified eligible studies and assessed risk of bias. We planned to pool data of studies considered clinically homogenous.

RESULTS

Thirty studies met inclusion criteria. None of the included studies were truly population-based: three included non-representative subgroups of the general population, 19 included differing clinical populations, while eight included professional athletes. All studies were judged to be at high risk of bias. Due to substantial clinical heterogeneity meta analysis was not possible. Across all studies, the prevalence estimates of cam morphology ranged from 5 to 75% of participants affected. We were unable to demonstrate a higher prevalence in selected subgroups such as athletes or those with hip pain.

CONCLUSIONS

There is currently insufficient high quality data to determine the true prevalence of cam morphology in the general population or selected subgroups. Well-designed population-based epidemiological studies that use homogenous case definitions are required to determine the prevalence of cam morphology and its relationship to hip pain.

Probability and heritability estimates on primary osteoarthritis of the hip leading to total hip arthroplasty: a nationwide population based follow-up study in Danish twins

INTRODUCTION

Primary hip osteoarthritis, radiographic as well as symptomatic, is highly associated with increasing age in both genders. However, little is known about the mechanisms behind this, in particular if this increase is caused by genetic factors. This study examined the risk and heritability of primary osteoarthritis of the hip leading to a total hip arthroplasty, and if this heritability increased with increasing age.

METHODS

In a nationwide population-based follow-up study 118,788 twins from the Danish Twin Register and 90,007 individuals from the Danish Hip Arthroplasty Register for the period 1995 to 2010 were examined. Our main outcomes were the cumulative incidence, proband-wise concordance and heritability on age, within-pair correlations in monozygotic and dizygotic twin pairs, and the genetic and environmental influence estimated in models taking into account that individuals may not have had a total hip arthroplasty at the time of follow-up.

RESULTS

There were 94,063 twins eligible for analyses, comprising 835 cases of 36 concordant and 763 discordant twin pairs. The probability increased particularly from 50 years of age. After sex and age adjustment a significant additive genetic component of 47% (12:79), a shared environmental component of 21% (2:76) and a unique environment component of 32% (21:41) accounted for the variation in population liability to total hip arthroplasty. The sex-adjusted proband-wise concordance and heritability on age indicated an increasing age-associated genetic influence onwards from 60 years of age.

CONCLUSION

The cumulative incidence in primary hip osteoarthritis leading to total hip arthroplasty increases in particular after the age of 50 years in both genders. Family factors of genes and shared environment are highly significant and account for 68% of the variation in the population liability to total hip arthroplasty; however, the genetic influence increases significantly from 60 years of age onwards.