Bilateral Femoroacetabular Impingement: What is the Fate of the Asymptomatic Hip?

Radiomics features outperform standard radiological measurements in detecting femoroacetabular impingement on three-dimensional magnetic resonance imaging

Femoroacetabular impingement (FAI) is a cause of hip pain and can lead to hip osteoarthritis. Radiological measurements obtained from radiographs or magnetic resonance imaging (MRI) are normally used for FAI diagnosis, but they require time-consuming manual interaction, which limits accuracy and reproducibility. This study compares standard radiologic measurements against radiomics features automatically extracted from MRI for the identification of FAI patients versus healthy subjects. Three-dimensional Dixon MRI of the pelvis were retrospectively collected for 10 patients with confirmed FAI and acquired for 10 healthy subjects. The femur and acetabulum were segmented bilaterally and associated radiomics features were extracted from the four MRI contrasts of the Dixon sequence (water-only, fat-only, in-phase, and out-of-phase). A radiologist collected 21 radiological measurements typically used in FAI. The Gini importance was used to define 9 subsets with the most predictive radiomics features and one subset for the most diagnostically relevant radiological measurements. For each subset, 100 Random Forest machine learning models were trained with different data splits and fivefold cross-validation to classify healthy subjects versus FAI patients. The average performance among the 100 models was computed for each subset and compared against the performance of the radiological measurements. One model trained using the radiomics features datasets yielded 100% accuracy in the detection of FAI, whereas all other radiomics features exceeded 80% accuracy. Radiological measurements yielded 74% accuracy, consistent with previous work. The results of this preliminary work highlight for the first time the potential of radiomics for fully automated FAI diagnosis.

Increased Alpha Angles and Younger Age Increase the Risk of Contralateral Femoral Acetabular Impingement Syndrome Symptom Development and Surgical Intervention: A Systematic Review

PURPOSE

To identify the preoperative risk factors associated with contralateral symptom development and surgical intervention for patients presenting with unilateral femoral acetabular impingement (FAI) syndrome.

METHODS

A literature search was performed using PubMed and Scopus computerized databases according to the 2020 Preferred Reporting Items for Systematic Meta-Analyses guidelines. Studies evaluating preoperative risk factors associated with the contralateral progression of FAI were included. Quality assessment was completed using the Methodological Index for Non-Randomized Studies criteria.

RESULTS

A total of 5 studies (n = 1,011 patients; mean age, 29.9 years) published from 2013 to 2022 met the inclusion/exclusion criteria. Mean follow-up ranged from 12 to 132 months. The overall rate of contralateral progression of symptomatic FAI ranged from 32.4% to 81%. Increased alpha angle was frequently reported factor associated with contralateral symptom progression, followed by decreased total arc of rotation, decreased internal rotation, reduced neck-shaft angle, and head-neck offset. The incidence rate of progression to contralateral surgery ranged from 15.7% to 24% of patients. Younger age was frequently reported factor associated with contralateral surgical intervention, followed by male sex, increased level of activity, and increased alpha angle.

CONCLUSIONS

Increased alpha angle and younger age were commonly reported risk factors associated with an increased risk of symptom development and surgical progression of contralateral FAI, respectively. The overall rate of contralateral progression of symptomatic FAI and the rate of progression to surgical intervention ranged up to 81% and 24%, respectively. This information may help both patients and surgeons to establish expectations regarding development of contralateral hip symptoms and possible need for surgery.

LEVEL OF EVIDENCE

Level III; systematic review of Level II-III studies.

Accelerated Bilateral Hip Arthroscopy (1 Week Apart): Outcomes Compared With Delayed Bilateral Procedure (4-12 Weeks) and Case-Control Matched Unilateral Arthroscopy

BACKGROUND

Staged bilateral hip arthroscopy is an option for athletes who have symptomatic bilateral femoroacetabular impingement; however, the optimal timing of the second procedure is unknown.

PURPOSE

To evaluate minimum 2-year outcomes for patients undergoing accelerated bilateral arthroscopy against those undergoing (1) delayed bilateral and (2) unilateral arthroscopy.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A retrospective review was performed of prospectively collected data from patients undergoing bilateral primary hip arthroscopy for femoroacetabular impingement between 2009 and 2022. Inclusion criteria entailed competitive athletes with concurrent bilateral symptoms at initial presentation. Exclusion criteria (either hip) were Tönnis grade >1, dysplasia (lateral center-edge angle <25°), Perthes disease, protrusio acetabuli, and avascular necrosis. Two groups were established based on the duration between procedures: within 7 days (accelerated group) and within 4 to 12 weeks (delayed group). Patients from the accelerated group were matched in a 1:2 ratio with patients undergoing unilateral surgery based on age ±2 years, sex, and athletic status. Minimum 2-year postoperative patient-reported outcomes (PROs) (including modified Harris Hip Score, University of California Los Angeles activity scale, 36-Item Short Form Health Survey, and Western Ontario and McMaster Universities Osteoarthritis Index), rates of achieving the minimal clinically important difference, rates of continuing to play main sport, and satisfaction were compared between groups.

RESULTS

A total of 131 athletes (262 hips) with bilateral femoroacetabular impingement were included: 91 in the accelerated group and 40 in the delayed group. Duration between surgeries was 0.99 ± 0.02 and 6.35 ± 2.18 weeks, respectively. All accelerated athletes were each successfully matched to 2 athletes with unilateral procedures (N = 182). All 3 groups demonstrated significant improvement from baseline across all PROs (P < .001 for all). Acquired change in PROs was similar and not significantly different between groups (P > .05). Satisfaction with relief from pain was achieved by 85.9% of patients in the accelerated group compared with 83.1% in the delayed group (P = .053) and 87.3% in the unilateral group (P = .933). The minimal clinically important difference for the modified Harris Hip Score was achieved by 84.9% of patients in the accelerated group compared with 91.5% in the delayed group (P = .212) and 87.6% in the unilateral group (P = .456). At 2 years postoperatively, the continue-to-play rate was 73.6% for the accelerated group compared with 77.1% for the delayed group (P = .577) and 73.0% for the unilateral group (P = .903). There were no increased complications associated with the accelerated group.

CONCLUSION

Accelerated bilateral hip arthroscopy 1 week apart was a safe and effective treatment option for athletes with bilateral symptoms. Improvement in PROs and continue-to-play rates were comparable with those after a delayed duration between procedures and with those case-control matched athletes undergoing unilateral arthroscopy.

Factors Associated With Disease Progression in the Contralateral Hip of Patients With Symptomatic Femoroacetabular Impingement: A Minimum 5-Year Analysis

BACKGROUND

Femoroacetabular impingement (FAI) is one of the most common causes of hip osteoarthritis, yet the factors controlling disease progression are poorly understood.

PURPOSE

To investigate rates of initial and subsequent symptoms in the contralateral hip of patients with FAI, and identify predictors of disease progression (symptom development and surgical intervention) in the contralateral hip.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

This prospective study included a minimum 5-year follow-up of the contralateral hip in 179 patients undergoing FAI surgery. Symptoms (moderate pain) and surgical progression were monitored. Univariate and multivariate analyses compared patient-specific and imaging characteristics of symptomatic patients with those who remained asymptomatic to identify factors associated with disease progression.

RESULTS

A total of 150 patients (84% follow-up) were followed for a mean of 7.1 years (range, 5-11 years). Thirty-nine of these patients (26% [39/150]) had contralateral hip symptoms at initial evaluation. Of those without contralateral hip symptoms at initial evaluation, 32% (36/111) had developed contralateral hip symptoms by latest follow-up. Those who developed symptoms during the study period had a lower anteroposterior head-neck offset ratio (0.153 vs 0.165; P = .005), decreased total arc of rotation in 90° of flexion (39.9° vs 51.1°; P = .005), and decreased external rotation in 90° of flexion (28.6° vs 37.1°; P = .003) compared with those who never developed symptoms. Age, sex, body mass index, alpha angle, lateral center-edge angle, internal rotation in flexion, and University of California, Los Angeles (UCLA), activity score were similar between these groups. Those with contralateral symptoms at initial evaluation progressed to contralateral surgery at a rate of 41% (16/39) and those who developed contralateral symptoms during the study period progressed to contralateral surgery at a rate of 28% (10/36). Among those with contalateral hip symptoms (either present initially or developed during study period)), younger age (24.6 vs 34.1 years; P < .001) and baseline UCLA activity score ≥9 (P = .003) were associated with progression to surgery. By Kaplan-Meier analysis, 64%, 54%, and 48% of patients remained free of contralateral hip symptoms at 2, 5, and 10 years.

CONCLUSION

At a mean follow-up of 7.1 years, significant symptoms in the contralateral hip of patients with FAI were present in approximately 50% of patients. FAI disease progression (symptom development and surgical intervention) was associated with decreased hip rotation arc, decreased external rotation, and decreased head-neck offset ratio. In symptomatic patients, younger age and UCLA activity score ≥9 were associated with progression to surgery. These findings represent important factors for patient counseling and risk modeling in FAI.

Bilateral hip arthroscopy for treating femoroacetabular impingement: a systematic review

PURPOSE

Femoroacetabular impingement (FAI) is a hip disorder which can often present bilaterally. The purpose of this systematic review was to explore the current practices for bilateral hip arthroscopy in treating FAI as they relate to outcomes and complications.

METHODS

This review has been conducted according to the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA). The electronic databases PubMed, MEDLINE, EMBASE, and CENTRAL (Cochrane Central Register of Controlled Trials) were searched from data inception to October 18th, 2020. The Methodological Index for Non-randomized Studies (MINORS) was used to assess study quality. Data are presented descriptively.

RESULTS

Overall, 19 studies were identified, comprising 957 patients (48.6% male) with a mean age of 27.9 ± 7.1 years and a mean follow-up of 31.7 ± 20.8 months. The majority of patients were treated with a staged bilateral hip arthroscopy (78.5%) with a mean duration between surgeries of 7.1 ± 4.0 months. Significant preoperative-to-postoperative improvements for clinical outcomes such as pain, hip function, and health-related daily living as well as radiographic outcomes were reported in six studies for staged procedures (p < 0.05) and three studies for simultaneous procedures (p < 0.02). Significant improvements in patient-reported outcomes (e.g., HOS-ADL, Pain, HOS-SS, mHHS, and NAHS) were found in favor of those undergoing a shorter delay between surgeries in three studies (i.e., < 3, 10 or 17 months) (p < 0.05) compared to those who had delayed surgeries (i.e., > 3, 10, or 17 months). The overall complication rate was 10.1% (97/957).

CONCLUSIONS

Bilateral surgery for FAI yields improved outcomes postoperatively and complication rates similar to unilateral surgery. The overall complication rate was 10.1% with the most common complication being revision surgery. Staged bilateral surgery is more commonly performed than simultaneous surgery. Clinicians should consider preoperative imaging, clinical history, and patient values when deciding between staged and simultaneous procedures for bilateral FAI surgery. Future studies are required to determine the optimal indications for simultaneous versus staged procedures, as well as the ideal timing between surgeries for the latter.

LEVEL OF EVIDENCE

Level IV.

Good Outcome Scores and Low Conversion Rate to THA 10 Years After Hip Arthroscopy for the Treatment of Femoroacetabular Impingement

BACKGROUND

Arthroscopic treatment of symptomatic femoroacetabular impingement (FAI) has promising short-term to mid-term results. In addition to treating acute pain or impaired function, the goal of hip-preserving surgery is to achieve a lasting improvement of hip function and to prevent the development of osteoarthritis. Long-term results are necessary to evaluate the effectiveness of surgical treatment and to further improve results by identifying factors associated with conversion to THA.

QUESTIONS/PURPOSES

(1) How do the Merle d'Aubigné-Postel scores change from before surgery to follow-up of at least 10 years in patients undergoing hip arthroscopy for the treatment of FAI? (2) What is the cumulative 10-year survival rate of hips with the endpoints of conversion to THA or a Merle d'Aubigné-Postel score less than 15? (3) Which factors are associated with conversion to THA?

METHODS

Between 2003 and 2008, we treated 63 patients (65 hips) for symptomatic FAI with hip arthroscopy at our institution. During that period, the indications for using arthroscopy were correction of anterior cam morphology and anterolateral rim trimming with debridement or reattachment of the labrum. We excluded patients who were younger than 16 years and those who had previous trauma or surgery of the hip. Based on that, 60 patients (62 hips) were eligible. A further 17% (10 of 60) of patients were excluded because the treatment was purely symptomatic without treatment of cam- and/or pincer-type morphology. Of the 50 patients (52 hips) included in the study, 2% (1) of patients were lost before the minimum study follow-up of 10 years, leaving 49 patients (51 hips) for analysis. The median (range) follow-up was 11 years (10 to 17). The median age at surgery was 33 years (16 to 63). Ninety percent (45 of 50) of patients were women. Of the 52 hips, 75% (39 of 52) underwent cam resection (femoral offset correction), 8% (4 of 52) underwent acetabular rim trimming, and 17% (9 of 52) had both procedures. Additionally, in 35% (18 of 52) of hips the labrum was debrided, in 31% (16 of 52) it was resected, and in 10% (5 of 52) of hips the labrum was reattached. The primary clinical outcome measurements were conversion to THA and the Merle d'Aubigné-Postel score. Kaplan-Meier survivorship and Cox regression analyses were performed with endpoints being conversion to THA or Merle d'Aubigné-Postel score less than 15 points.

RESULTS

The clinical result at 10 years of follow-up was good. The median improvement of the Merle d'Aubigné-Postel score was 3 points (interquartile range 2 to 4), to a median score at last follow-up of 17 points (range 10 to 18). The cumulative 10-year survival rate was 92% (95% CI 85% to 99%) with the endpoints of conversion to THA or Merle d'Aubigné-Postel score less than 15. Factors associated with conversion to THA were each year of advancing age at the time of surgery (hazard ratio 1.1 [95% CI 1.0 to 1.3]; p = 0.01) and preoperative Tönnis Grade 1 compared with Tönnis Grade 0 (no sign of arthritis; HR 17 [95% CI 1.8 to 166]; p = 0.01).

CONCLUSION

In this series, more than 90% of patients retained their native hips and reported good patient-reported outcome scores at least 10 years after arthroscopic treatment of symptomatic FAI. Younger patients fared better in this series, as did hips without signs of osteoarthritis. Future studies with prospective comparisons of treatment groups are needed to determine how best to treat complex impingement morphologies.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Editorial Commentary: Bilateral Femoroacetabular Impingement Syndrome: What We Know Now and Where Do We Go From Here?

Patients with bilateral femoroacetabular impingement syndrome treated with either staged or simultaneous hip arthroscopy have similar postoperative outcomes compared with patients undergoing unilateral procedures. A longer duration between surgeries is associated with inferior outcomes; however, the reasons underlying this trend are unclear. Identifying prognostic variables that are associated with contralateral symptom onset and disease progression are important goals for future investigation.

Editorial Commentary: Modified False-Profile View-Two Birds With One Stone?

Pathology in the hip is most commonly described using radiographic parameters. Accurately delineating this pathology is paramount in proper diagnosis and care. The anterior center-edge angle measures the anterior coverage of the acetabulum, which has implications in treating the hip. The modified false-profile view will allow visualization of not only the anterior coverage of the femoral head but also the patient's alpha angle. As such, the modified false-profile view could replace both the standard false-profile view and the 45° Dunn view, essentially reducing by 1 the number of images required to evaluate patients presenting with hip symptoms. A disadvantage is that hip instability may be more difficult to identify radiographically.