Radiographic Diagnosis of Pincer-Type Femoroacetabular Impingement: A Systematic Review

Imaging of Disease and Normal Variant Patterns in Pediatric Hips

The pediatric hip undergoes significant changes from infancy through adolescence. Proper maturation is crucial for the development of a stable and functional hip joint. Imaging interpretation of the pediatric hip requires distinguishing normal variants and maturation patterns from pathology. We review femoral ossification centers, variants, and conditions that affect the proximal femur, such as Legg-Calvé-Perthes disease; the acetabulum, such as developmental hip dysplasia; the acetabular labrum, such as femoroacetabular impingement; and synovial pathology in children through adolescence. Understanding the spectrum of hip conditions and using advanced imaging techniques are essential for the accurate diagnosis and effective management of pediatric hip disorders.

Primary Hip Arthroscopy is Associated with Earlier Achievement of Substantial Clinical Benefit Compared to Revision Hip Arthroscopy for Femoroacetabular Impingement Syndrome

PURPOSE

To compare time to achievement of clinically significant outcomes (CSOs) between patients undergoing primary and revision hip arthroscopy (HA) for femoroacetabular impingement syndrome (FAIS).

METHODS

Patients undergoing primary and revision HA for FAIS with complete 6-month, 1-year, and 2-year Hip Outcome Score - Activities of Daily Living (HOS-ADL) and Sport Subscale (HOS-SS) were identified. Revision patients were propensity matched 1:4 to primary HA patients, controlling for age, sex, and body mass index (BMI). Time to achievement of minimal clinically important difference (MCID) and substantial clinical benefit (SCB) were compared alongside cumulative CSO achievement at 6, 12, and 24 months. Hazard ratios (HR) for predictors of earlier CSO achievement were identified with multivariate Cox regressions.

RESULTS

Fifty revision HA patients were propensity-matched to 200 primary HA patients of similar age, sex, and BMI. Primary HA patients demonstrated a greater prevalence of regular preoperative physical activity (87% vs. 59%, p<0.001). Primary HA patients showed significantly greater SCB achievement for HOS-ADL at 6, 12, and 24 months (p<0.001) and significantly greater SCB achievement for HOS-SS at 12 and 24 months (p≤0.001) compared to revision HA patients. Primary HA patients achieved SCB for HOS-ADL (p<0.001) and HOS-SS (p=0.015) quicker than revision HA patients. Predictors of earlier CSO achievement included preoperative PRO score (HR: 0.98-1.02, p≤0.007), lower BMI (HR: 0.97, p=0.038), presence of physical activity (HR: 1.51, p=0.038), and absence of revision status (HR: 0.52-0.56, p≤0.019).

CONCLUSIONS

Primary HA patients showed a quicker time to SCB achievement for HOS-ADL and HOS-SS compared to revision HA patients. Preoperative PRO score, lower BMI, regular physical activity, and primary HA status predicted earlier CSO achievement.

LEVEL OF EVIDENCE

Level III, retrospective comparative series.

Pincer Morphology Is Not Associated With Hip Osteoarthritis Unless Hip Pain Is Present: Follow-Up Data From a Prospective Cohort Study

OBJECTIVE

The objective of this study was to assess the relationship between pincer morphology and radiographic hip osteoarthritis (RHOA) over 2, 5, 8, and 10 years' follow-up and to study the interaction between pincer morphology and pain.

METHODS

Individuals from the prospective Cohort Hip and Cohort Knee study were drawn. Anteroposterior pelvic and false profile radiographs were obtained. Hips free of definite RHOA (Kellgren and Lawrence [KL] grade 0 or 1) at baseline were included. Pincer morphology was defined as a lateral or anterior center edge angle or both ≥40° at baseline. Incident RHOA was defined as KL ≥ 2 or total hip replacement at follow-up. Multivariable logistic regression with generalized estimating equations estimated the associations at follow-up. Associations were expressed as unadjusted odds ratios (ORs) and adjusted ORs with 95% confidence intervals (CIs). An interaction term was added to investigate whether pincer morphology had a different effect on symptomatic hips.

RESULTS

Incident RHOA developed in 69 hips (5%) at 2 years' follow-up, in 178 hips (14%) at 5 years' follow-up, in 279 hips (24%) at 8 years' follow-up, and in 495 hips (42%) at 10 years' follow-up. No significant associations were found between pincer morphology and incident RHOA (adjusted OR 0.35 [95% CI 0.06-2.15]; adjusted OR 1.50 [95% CI 0.94-2.38]). Significant interactions between pain and anterior pincer morphology in predicting incident RHOA were found at 5, 8, and 10 years' follow-up (OR 1.97 [95% CI 1.03-3.78]; OR 3.41 [95% CI 1.35-8.61]).

CONCLUSION

No associations were found between radiographic pincer morphology and incident RHOA at any follow-up moment. Anteriorly located pincer morphology with hip pain, however, was significantly associated with incident RHOA. This highlights the importance of studying symptoms and hip morphology simultaneously.

Hip and Pelvis Movement Patterns in Patients With Femoroacetabular Impingement Syndrome Differ From Controls and Change After Hip Arthroscopy During a Step-Down Pivot-Turn Task

Background

Alterations in hip kinematics during functional tasks occur in positions that cause anterior impingement in patients with femoroacetabular impingement (FAI) syndrome. However, tasks that do not promote motions of symptomatic hip impingement remain understudied.

Purpose

To compare movement patterns of the hip and pelvis during a step-down pivot-turn task between patients with FAI and controls as well as in patients with FAI before and after hip arthroscopy.

Study Design

Controlled laboratory study.

Methods

Three-dimensional motion capture was acquired in 32 patients with FAI and 27 controls during a step-down pivot-turn task. An FAI subsample (n = 14) completed testing 9.2 ± 2.0 months (mean ± SD; range, 5.8-13.1 months) after hip arthroscopy. Statistical parametric mapping analysis was used to analyze hip and pelvis time series waveforms (1) between the FAI and control groups, (2) in the FAI group before versus after hip arthroscopy, and (3) in the FAI group after hip arthroscopy versus the control group. Continuous parametric variables were analyzed by paired t test and nonparametric variables by chi-square test.

Results

There were no significant differences in demographics between the FAI and control groups. Before hip arthroscopy, patients with FAI demonstrated reduced hip flexion (P = .041) and external rotation (P = .027), as well as decreased anterior pelvic tilt (P = .049) and forward rotation (P = .043), when compared with controls. After hip arthroscopy, patients demonstrated greater hip flexion (P < .001) and external rotation of the operative hip (P < .001), in addition to increased anterior pelvic tilt (P≤ .036) and pelvic rise (P≤ .049), as compared with preoperative values. Postoperatively, the FAI group demonstrated greater hip flexion (P≤ .047) and lower forward pelvic rotation (P = .003) as compared with the control group.

Conclusion

Movement pattern differences between the FAI and control groups during the nonimpingement-related step-down pivot-turn task were characterized by differences in the sagittal and transverse planes of the hip and pelvis. After hip arthroscopy, patients exhibited greater hip flexion and external rotation and increased pelvic anterior tilt and pelvic rise as compared with presurgery. When compared with controls, patients with FAI demonstrated greater hip flexion and lower pelvic forward rotation postoperatively.

Clinical Relevance

These findings indicate that hip and pelvis biomechanics are altered even during tasks that do not reproduce the anterior impingement position.

A comprehensive review of hip arthroscopy techniques and outcomes

Transforming the orthopedic landscape, hip arthroscopy pioneers a minimally invasive surgical approach for diagnosing and addressing hip pathologies. With its origins dating back to Burman's 1931 cadaveric study, this groundbreaking technique gained clinical relevance in 1939 through Takagi's report. However, the 1980s marked the actual emergence of hip arthroscopy for treating a wide range of hip disorders. Now, a staple in modern orthopedics, hip arthroscopy empowers patients with previously undiagnosed and untreated hip conditions, enabling them to obtain relief and reclaim their lives. By employing a compact camera and specialized tools, surgeons expertly navigate the hip joint, performing procedures from excising loose bodies and mending labral tears to addressing femoroacetabular impingement and tackling other intricate issues. This innovative approach has dramatically elevated patients' quality of life, allowing them to embrace targeted treatments and resume daily activities without resorting to lifestyle alterations.

Patients Aged 40 Years and Older Demonstrate Durable and Comparable Results to Patients Aged Less Than 40 Years After Primary Hip Arthroscopy for Femoroacetabular Impingement Syndrome: A Propensity Matched Study at Minimum 10-Year Follow-Up

PURPOSE

The purpose of the present study was to compare clinical outcomes and rates of secondary surgery, including revision hip arthroscopy and conversion to total hip arthroplasty (THA), after primary hip arthroscopy for femoroacetabular impingement syndrome (FAIS) in patients ≥40 years of age at minimum 10-year follow-up compared with a propensity-matched control group of patients <40 years.

METHODS

A retrospective cohort study was performed for patients who underwent primary hip arthroscopy for FAIS between January 2012 and February 2013. Patients ≥40 years old were propensity matched in a 1:1 ratio by sex and body mass index to patients <40 years old. Patient-reported outcomes (PROs) including Hip Outcome Score for Activities of Daily Living and Sports-Specific subscales, modified Harris Hip, International Hip Outcome Tool-12, and Visual Analog Scale for Pain and Satisfaction were collected. Rates of minimal clinically important difference (MCID) and patient-acceptable symptomatic state (PASS) achievement at 10 years were evaluated and compared between groups. Rates of secondary surgery including revision hip arthroscopy and conversion to THA were evaluated. Gross survivorship between cohorts was evaluated using a Kaplan-Meier curve.

RESULTS

Fifty-three patients aged ≥40 (age 48.3 ± 5.8 years) were successfully matched to 53 patients aged <40 (age: 28.9 ± 7.2, <0.001). There were no other preoperative group differences regarding patient demographics, characteristics, or radiographic findings. Both groups demonstrated significant improvement regarding all PROs at a minimum of 10 years' follow-up (P < .001 for all). No significant difference was noted between cohorts regarding any delta (preoperative to 10-year postoperative) scores (P > .05 for all). High rates of MCID and PASS achievement were achieved in both cohorts, with no significant differences in any PRO measure (P > .05 for all). No significant differences in rates of complications (age ≥40: 2.0%, age <40: 7.7%, P = .363), rates of revision (age ≥40: 7.5%, age <40: 9.4%, P = .999), or conversion to THA (age ≥40: 13.2%, age <40: 3.8%, P = .161) were identified. On Kaplan-Meier analysis, no significant difference (P = .321) was demonstrated in overall gross survivorship between cohorts.

CONCLUSION

Patients with age ≥40 with FAIS undergoing primary hip arthroscopy demonstrated durable and comparable 10-year PRO and rates of MCID and PASS achievement compared with a propensity-matched cohort of age <40 counterparts.

LEVEL OF EVIDENCE

Level III, retrospective comparative prognostic trial.

Hip Arthroscopic Surgery With Chondrolabral Refixation, Osteochondroplasty, and Routine Capsular Closure for Femoroacetabular Impingement Syndrome: Clinical Outcomes at a Minimum 10-Year Follow-up

BACKGROUND

Hip arthroscopic surgery for femoroacetabular impingement syndrome (FAIS) has proven to be an effective surgical intervention, with high rates of return to sport and work as well as favorable outcomes at short- and midterm follow-up. However, limited data exist on outcomes at long-term follow-up.

PURPOSE

To evaluate patient-reported outcomes (PROs) at a minimum 10-year follow-up after primary hip arthroscopic surgery including labral repair, femoral osteochondroplasty, acetabular osteochondroplasty, and capsular closure for FAIS.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Patients who underwent primary hip arthroscopic surgery for FAIS between June 2012 and January 2013 were identified. PROs were collected preoperatively and at a minimum of 10 years postoperatively, including the Hip Outcome Score-Activities of Daily Living (HOS-ADL), Hip Outcome Score-Sports Subscale (HOS-SS), modified Harris Hip Score (mHHS), International Hip Outcome Tool-12 (iHOT-12), and visual analog scale (VAS) for pain and satisfaction. Unique minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) thresholds were calculated, and their rates of achievement were analyzed. An alpha level of <.05 was used to determine statistical significance.

RESULTS

A total of 94 patients (55 female; mean age, 34.3 ± 12.4 years) were analyzed with a mean follow-up of 10.1 ± 0.3 years (range, 10.0-10.7 years). Patients demonstrated significant 10-year improvement across all PRO measures (P < .001). MCID and PASS thresholds were calculated as follows: HOS-ADL (10.4 and 85.3, respectively), HOS-SS (14.6 and 60.2, respectively), mHHS (8.8 and 76.0, respectively), VAS pain (14.6 and 27.5, respectively), and iHOT-12 (PASS: 71.4). The majority of patients achieved the MCID and PASS for each PRO measure: HOS-ADL (73.4% and 70.9%, respectively), HOS-SS (78.5% and 77.2%, respectively), mHHS (81.0% and 70.9%, respectively), VAS pain (88.6% and 70.9%, respectively), and iHOT-12 (PASS: 73.4%). Overall, 9 patients (9.6%) underwent subsequent revision hip arthroscopic surgery at a mean 4.9 ± 3.7 years (range, 1.1-10.1 years) postoperatively, and 6 patients (6.4%) underwent conversion to total hip arthroplasty at a mean 4.1 ± 3.1 years (range, 0.9-9.3 years) postoperatively.

CONCLUSION

Patients who underwent primary hip arthroscopic surgery for FAIS utilizing contemporary methods of labral repair, acetabular and/or femoral osteochondroplasty, and capsular closure commonly experienced sustained clinical improvement and reported high levels of satisfaction at a minimum 10-year follow-up with low rates of reoperation.

Functional Outcome Scores and Conversion to Total Hip Arthroplasty After Hip Arthroscopy for Femoroacetabular Impingement Syndrome in Patients With Tönnis Grade 1 Versus Grade 0 Arthritis: A Propensity-Matched Study at Minimum 10-Year Follow-up

BACKGROUND

Hip arthroscopy has become the mainstay surgical intervention for the treatment of femoroacetabular impingement syndrome (FAIS). However, postoperative outcomes and rates of secondary surgery are mixed in patients with differing levels of preoperative osteoarthritis (OA). Furthermore, there is a paucity of literature comparing patients with and without OA at long-term follow-up.

PURPOSE

To compare outcomes and rates of secondary surgery at minimum 10-year follow-up, including revision hip arthroscopy and conversion to total hip arthroplasty (THA), in patients with Tönnis grade 1 undergoing hip arthroscopy for FAIS compared with a propensity-matched control group of patients with Tönnis grade 0.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients who underwent primary hip arthroscopy for FAIS between January 2012 and February 2013 were identified. Patients with Tönnis grade 1 were propensity matched in a 1:2 ratio by age, sex, and body mass index (BMI) to patients with Tönnis grade 0. Patient-reported outcomes (PROs) were collected at varying timepoints including preoperatively and 1, 2, 5, and 10 years postoperatively and compared between the 2 cohorts. Rates of minimal clinically important difference (MCID) and Patient Acceptable Symptom State (PASS) achievement at 10 years were evaluated and compared between groups. Rates of secondary surgery including revision hip arthroscopy and conversion to total hip arthroplasty (THA) were evaluated. Gross survivorship between cohorts was evaluated using a Kaplan-Meier gross survivorship curve. A subanalysis was performed comparing patients with Tönnis grade 1 who converted to THA and those who did not.

RESULTS

A total of 31 patients with Tönnis grade 1 (age, 42.6 ± 9.0 years; BMI, 28.0 ± 6.3) were successfully matched to 62 patients with Tönnis grade 0 (age, 42.1 ± 8.5, P = .805; BMI, 26.1 ± 3.9, P = .117). Both the Tönnis grade 1 and Tönnis grade 0 groups demonstrated significant improvements regarding all PROs at minimum 10 years (P < .05 for all), except for the Hip Outcome Score Activities of Daily Living subscale (HOS-ADL) (P = .066) in the Tönnis grade 1 cohort. No significant difference (P > .05 for all) was noted between cohorts regarding any 10-year PRO. When the authors evaluated comparisons between preoperative and 1-, 2-, 5-, and 10-year PRO measures, significant differences were noted between cohorts regarding 2-year HOS-ADL (P = .021), Hip Outcome Score Sports-Specific subscale (P = .016), and modified Harris Hip Score (P = .026); otherwise, differences did not reach significance. High rates of 10-year MCID and PASS achievement were seen, with no significant differences between groups. Patients with Tönnis grade 1 had significantly higher rates of conversion to THA compared with patients who had Tönnis grade 0 (25.8% vs 4.8%; P = .006). Patients with Tönnis grade 1 had significantly lower gross survivorship compared with those who had Tönnis grade 0 (71.0% vs 85.5%, respectively; P = .04).

CONCLUSION

Hip arthroscopy confers comparable postoperative clinical improvements to patients who have FAIS with and without mild OA; however, the benefits among patients with mild OA may be less durable. Patients with Tönnis grade 1 had significantly higher conversion to THA and reduced gross survivorship compared with patients with no evidence of preoperative OA, suggesting that patients with evidence of OA may need to be cautioned on the higher rate of conversion surgery.

Femoral and acetabular features explain acetabular contact pressure sensitivity to hip internal rotation in persons with cam morphology: A finite element analysis

BACKGROUND

Femoroacetabular impingement is characterized by premature contact between the proximal femur and acetabulum. The loss of femoral head-neck concavity associated with cam morphology leads to mechanical impingement during hip flexion and internal rotation. Other femoral and acetabular features have been linked with mechanical impingement but have not been comprehensively investigated. This study sought to determine which bony features are most influential in contributing to mechanical impingement in persons with a cam morphology.

METHODS

Twenty individuals (10 female, 10 male) with a cam morphology participated. Finite element analyses incorporating subject-specific bony geometry derived from computed tomography scans were used to determine which femoral (alpha angle and femoral neck-shaft angle) and acetabular (anteversion angle, inclination angle, depth, and lateral center-edge angle) features accentuate acetabular contact pressure with increasing degrees of hip internal rotation with the hip flexed to 90°. To determine the best predictors of acetabular contact pressure sensitivity to internal rotation, all morphological variables were included in a stepwise regression with the final model subjected to a bootstrapping procedure.

FINDINGS

The stepwise regression revealed that femoral neck-shaft angle, acetabular anteversion angle, acetabular inclination angle, and acetabular depth were the best combination of variables to predict contact pressure sensitivity to internal rotation, explaining 55% of the variance. Results of the bootstrap analysis revealed that a median value of 65% [37%, 89%] variance in sensitivity could be explained by these morphological variables.

INTERPRETATION

Mechanical impingement and the concomitant acetabular contact pressure are modulated by multiple femoral and acetabular features in persons with a cam morphology.

Intraoperative Use of Ultrasound for Assessing Cam Deformity and Cam Resection

The use of intraoperative fluoroscopy is standard among hip arthroscopist to evaluate and confirm the adequacy of cam resection in patients with femoroacetabular impingement syndrome. However, given the inherent limitations of fluoroscopy, additional intraoperative imaging, such as ultrasound, should be pursued. We offer a technique to measure alpha angles intraoperatively using ultrasound to determine adequate cam resection.

A radiomics approach to the diagnosis of femoroacetabular impingement

Introduction

Femoroacetabular Impingement (FAI) is a hip pathology characterized by impingement of the femoral head-neck junction against the acetabular rim, due to abnormalities in bone morphology. FAI is normally diagnosed by manual evaluation of morphologic features on magnetic resonance imaging (MRI). In this study, we assess, for the first time, the feasibility of using radiomics to detect FAI by automatically extracting quantitative features from images.

Material and methods

17 patients diagnosed with monolateral FAI underwent pre-surgical MR imaging, including a 3D Dixon sequence of the pelvis. An expert radiologist drew regions of interest on the water-only Dixon images outlining femur and acetabulum in both impingement (IJ) and healthy joints (HJ). 182 radiomic features were extracted for each hip. The dataset numerosity was increased by 60 times with an ad-hoc data augmentation tool. Features were subdivided by type and region in 24 subsets. For each, a univariate ANOVA F-value analysis was applied to find the 5 features most correlated with IJ based on p-value, for a total of 48 subsets. For each subset, a K-nearest neighbor model was trained to differentiate between IJ and HJ using the values of the radiomic features in the subset as input. The training was repeated 100 times, randomly subdividing the data with 75%/25% training/testing.

Results

The texture-based gray level features yielded the highest prediction max accuracy (0.972) with the smallest subset of features. This suggests that the gray image values are more homogeneously distributed in the HJ in comparison to IJ, which could be due to stress-related inflammation resulting from impingement.

Conclusions

We showed that radiomics can automatically distinguish IJ from HJ using water-only Dixon MRI. To our knowledge, this is the first application of radiomics for FAI diagnosis. We reported an accuracy greater than 97%, which is higher than the 90% accuracy for detecting FAI reported for standard diagnostic tests (90%). Our proposed radiomic analysis could be combined with methods for automated joint segmentation to rapidly identify patients with FAI, avoiding time-consuming radiological measurements of bone morphology.

Combined 3-Dimensional CT and Multidirectional CT Arthrography for Femoroacetabular Impingement and Hip Lesions: A Cross-sectional Study Comparing Imaging and Hip Arthroscopic Surgery Findings

Background

There is limited research investigating the diagnostic strength of 3-dimensional computed tomography (3D-CT) and multidirectional CT arthrography (CTA) for femoroacetabular impingement (FAI) and related hip lesions.

Purpose

To evaluate the diagnostic strength of combined 3D-CT and CTA in patients with FAI and related hip lesions by comparing it with hip arthroscopic surgery findings.

Study Design

Cohort study (diagnosis); Level of evidence, 2.

Methods

This study included patients who were suspected of having FAI and related hip lesions and who underwent a combination of 3D-CT and CTA and subsequent hip arthroscopic surgery between December 2013 and December 2017. The CT and intraoperative arthroscopic findings were recorded and compared. The sensitivity, specificity, and accuracy of 3D-CT for FAI and those of CTA for related hip lesions were calculated.

Results

A total of 114 patients with 114 hips were included in our study. There were 101 patients with positive findings and 13 patients with negative findings for FAI (including cam, pincer, and combined morphology) according to 3D-CT. The sensitivity, specificity, and accuracy of 3D-CT for FAI were 91.58%, 57.14%, and 89.47%, respectively. The sensitivity, specificity, and accuracy of CTA for labral tears were 94.64%, 100.00%, and 94.73%, respectively. For acetabular cartilage defects, the sensitivity, specificity, and accuracy of CTA were 60.71%, 91.37%, and 76.31%, respectively. For femoral cartilage defects, the sensitivity, specificity, and accuracy of CTA were 82.22%, 76.81%, and 78.94%, respectively.

Conclusion

The study results indicated that 3D-CT was able to provide excellent accuracy for FAI compared with hip arthroscopic surgery findings. In addition, multidirectional CTA demonstrated promising diagnostic strength for hip lesions such as labral tears and chondral defects.

Gluteal activation during squatting reduces acetabular contact pressure in persons with femoroacetabular impingement syndrome: A patient-specific finite element analysis

BACKGROUND

Femoroacetabular impingement syndrome is a motion-related clinical disorder resulting from abnormal hip joint morphology. Mechanical impingement, in which the aspherical femoral head (cam morphology) abuts with the acetabular rim, is created with simultaneous hip flexion, internal rotation, and adduction. Impaired function of the gluteal muscles may be contributory to femoroacetabular impingement syndrome progression. The purpose of this study was to assess the influence of gluteal muscle recruitment on acetabular contact pressure during squatting in persons with cam femoroacetabular impingement syndrome.

METHODS

Eight individuals (4 males, 4 females) with a diagnosis of cam femoroacetabular impingement syndrome underwent CT imaging of the pelvis and proximal femora, and a biomechanical assessment of squatting (kinematics, kinetics, and electromyography). Two maximal depth bodyweight squat conditions were evaluated: 1) non-cued squatting; and 2) cued gluteal activation squatting. Utilizing subject-specific electromyography-driven hip and finite element modeling approaches, hip muscle activation, kinematics, bone-on-bone contact forces, and peak acetabular contact pressure were compared between squat conditions.

FINDINGS

Modest increases in gluteus maximus (7% MVIC, P < 0.0001) and medius (6% MVIC, P = 0.009) activation were able to reduce hip internal rotation on average 5° (P = 0.024), and in doing so reduced acetabular contact pressure by 32% (P = 0.023). Reductions in acetabular contact pressure occurred despite no change in hip abduction and increased bone-on-bone contact forces occurring in the cued gluteal activation condition.

INTERPRETATION

Our findings highlight the importance of gluteal activation in minimizing mechanical impingement and provide a foundation for interventions aimed at preventing the development and progression of femoroacetabular impingement syndrome.

Open and arthroscopic management of femoroacetabular impingement: a review of current concepts

Femoroacetabular impingement (FAI) is a common femoral and/or acetabular abnormality that can cause progressive damage to the hip and osteoarthritis. FAI can be the result of femoral head/neck overgrowth, acetabular overgrowth or both femoral and acetabular abnormalities, resulting in a loss of native hip biomechanics and pain upon hip flexion and rotation. Radiographic evidence can include loss of sphericity of the femoral neck (cam impingement) and/or acetabular retroversion with focal or global overcoverage (pincer impingement). Operative intervention is indicated in symptomatic patients after failed conservative management with radiographic evidence of impingement and minimal arthritic changes of the hip, with the goal of restoring normal hip biomechanics and reducing pain. This is done by correcting the femoral head-neck relationship to the acetabulum through femoral and/or acetabular osteoplasty and treatment of concomitant hip pathology. In pincer impingement cases with small lunate surfaces, reverse periacetabular osteotomy is indicated as acetabular osteoplasty can decrease an already small articular surface. While surgical dislocation is regarded as the traditional gold standard, hip arthroscopy has become widely utilized in recent years. Studies comparing both open surgery and arthroscopy have shown comparable long-term pain reduction and improvements in clinical measures of hip function, as well as similar conversion rates to total hip arthroplasty. However, arthroscopy has trended toward earlier improvement, quicker recovery and faster return to sports. The purpose of this study was to review the recent literature on open and arthroscopic management of FAI.

An Updated Review of Femoroacetabular Impingement Syndrome

Femoroacetabular impingement (FAI) is a chronic hip condition caused by femoral head and acetabular malformations resulting in abnormal contact across the joint. FAI often leads to labral, cartilaginous, and tissue damage that predispose this patient population to early osteoarthritis (OA). There are a variety of factors that increase the risk for FAI including younger age, Caucasian background, familial FAIS morphology, and competing in high-intensity sports during adolescence. Slow-onset, persistent groin pain is the most frequent initial presenting symptom. On physical examination, patients will typically have a positive FADIR test (flexion, adduction, internal rotation), also known as a positive impingement sign. FAI syndrome can be organized into three classifications; cam, pincer, or mixed. This classification refers to the characteristic morphological changes of the bony structures. The primary imaging modality for diagnosing FAI is a plain radiograph of the pelvis, which can be used to measure the alpha angle and the lateral center edge angle used to quantify severity. Conservative treatment is typically considered first-line treatment for mild to moderate FAI syndrome; however, the outcomes following postoperative surgical intervention have demonstrated excellent results. The most common surgical treatment option for FAI is done arthroscopically.

Outcomes for the Arthroscopic Treatment of Femoroacetabular Impingement Syndrome With Acetabular Retroversion: A 3D Computed Tomography Analysis

BACKGROUND

Increased attention has been directed toward the acetabular morphology in the management of patients with femoroacetabular impingement syndrome (FAIS). Whether acetabular version influences patient-reported outcomes remains poorly understood.

PURPOSE

To use computed tomography (CT)-based 3-dimensional (3D) bone models to (1) quantify acetabular version in patients with FAIS, (2) compare acetabular version on 3D bone models with current plain radiographic parameters, and (3) explore the relationship between the magnitude of acetabular version and minimum 2-year clinical outcomes after hip arthroscopy.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Three-dimensional models of the pelvis and femur were generated by semiautomated segmentation and aligned to a standard coordinate system. Acetabular version was quantified at the 3-o'clock position, and 3 groups were identified: acetabular retroversion (AR; <15°), normal acetabular version (NV; 15°-25°), and acetabular anteversion (AA; >25°). Patient demographic characteristics, plain radiographic parameters, and clinical outcomes were analyzed, including the Hip Outcome Score-Activities of Daily Living, Hip Outcome Score-Sports Subscale, modified Harris Hip Score (mHHS), International Hip Outcome Tool (iHOT-12), and visual analog scale (VAS) for pain and satisfaction.

RESULTS

Preoperative CT scans were acquired in 105 consecutive patients before hip arthroscopy for FAIS, of which 84 (80.0%) completed minimum 2-year patient-reported outcomes. The mean ± SD age and body mass index of patients were 33.9 ± 12.6 years and 26.0 ± 5.4, respectively; 70.2% were female. The number of patients and the mean central acetabular version within each group were as follows: AR (n = 12; 11.3°± 2.7°), NV (n = 56; 20.7°± 2.9°), and AA (n = 16; 28.5°± 2.7°). Posterior wall sign was the only plain radiographic parameter that was significantly more observed in the AR group than in the other 2 groups. At minimum 2-year follow-up, significant between-group differences in the mHHS, iHOT-12, and VAS for pain and satisfaction (P < .05) were appreciated, while post hoc analysis with Bonferroni correction (P < .0167) found lower scores on the mHHS, iHOT-12, and VAS for pain and satisfaction in patients with AR as compared with NV. Lower scores on the VAS for satisfaction were reported in patients with AR when compared with AA (P = .006) but not on the mHHS (P = .023), iHOT-12 (P = .032), or VAS for pain (P = .072).

CONCLUSION

Traditional plain radiographic indices to describe AR, including crossover sign and ischial spine sign, were not reliable in defining AR according to 3D models derived from CT scans. Only the posterior wall sign was observed in a higher proportion in the AR group. Patients with AR demonstrated inferior outcomes when compared with patients with NV and AA after hip arthroscopy for FAIS.

Pre- and intraoperative decision-making challenges in hip arthroscopy for femoroacetabular impingement

There has been a marked increase in the number of hip arthroscopies performed over the past 16 years, primarily in the management of femoroacetabular impingement (FAI). Insights into the pathoanatomy of FAI, and high-level evidence supporting the clinical effectiveness of arthroscopy in the management of FAI, have fuelled this trend. Arthroscopic management of labral tears with repair may have superior results compared with debridement, and there is now emerging evidence to support reconstructive options where repair is not possible. In situations where an interportal capsulotomy is performed to facilitate access, data now support closure of the capsule in selective cases where there is an increased risk of postoperative instability. Preoperative planning is an integral component of bony corrective surgery in FAI, and this has evolved to include computer-planned resection. However, the benefit of this remains controversial. Hip instability is now widely accepted, and diagnostic criteria and treatment are becoming increasingly refined. Instability can also be present with FAI or develop as a result of FAI treatment. In this annotation, we outline major current controversies relating to decision-making in hip arthroscopy for FAI. Cite this article: Bone Joint J 2022;104-B(5):532-540.

Correlation between the range of rotation of the hip and the radiographic signs of cam and pincer morphology in femoroacetabular impingement syndrome

Objective

To determine whether hip rotation correlates with the radiographic signs of cam or pincer deformity after hip arthroscopy in patients with femoroacetabular impingement syndrome.

Materials and Methods

This was a single-center retrospective study of data collected between 2014 and 2017. The study sample included 65 patients between 18 and 55 years of age who underwent hip arthroscopy for the treatment of unilateral femoroacetabular impingement. The following data were collected for the periods prior to and six months after surgery range of medial and lateral rotation of the hip; measures on anteroposterior X-rays of the pelvis obtained in the standing position and on ateral X-rays in the Ducroquet profile view; and score on the 33-item International Hip Outcome Tool.

Results

Mean preoperative and postoperative values were as follows: 19.26 ± 10.39° and 30.95 ± 3.52°, respectively, for medial rotation of the hip (p < 0.001); 73.85 ± 6.62° and 68.12 ± 5.04°, respectively, for the anteroposterior alpha angle (p < 0.001); 56.97 ± 6.09° and 50.61 ± 5.39°, respectively, for the lateral alpha angle (p < 0.001); and 0.17 ± 0.11 and 0.07 ± 0.08, respectively, for the acetabular retroversion index (p < 0.001). The crossover sign was identified in 75.4% of the patients before surgery and in 44.6% after (p < 0.001). Although there was an increase in the range of hip rotation and an improvement in radiographic parameters after arthroscopy, we detected no direct correlation between the two.

Conclusion

Hip arthroscopy can improve medial rotation of the hip, as well as reducing cam and pincer deformities, in patients with femoroacetabular impingement syndrome. However, those findings do not appear to be directly correlated.

Return to Sport in Athletes With Borderline Hip Dysplasia After Hip Arthroscopy for Femoroacetabular Impingement Syndrome

BACKGROUND

Data on outcomes in patients with borderline hip dysplasia (BHD) who undergo hip arthroscopy remain limited, particularly in regard to return to sport (RTS).

PURPOSE

To evaluate outcomes in patients with BHD and their ability to RTS after hip arthroscopy for treatment of femoroacetabular impingement syndrome (FAIS).

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Consecutive patients with self-reported athletic activity and radiographic evidence of BHD, characterized by a lateral femoral center-edge angle (LCEA) between 18° and 25° and a Tönnis angle >10°, who underwent hip arthroscopy for FAIS between November 2014 and March 2017 were identified. Patient characteristics and clinical outcomes including the Hip Outcome Score-Activities of Daily Living (HOS-ADL), Hip Outcome Score-Sports Subscale (HOS-SS), modified Harris Hip Score (mHHS), international Hip Outcome Tool (iHOT-12), and visual analog scale (VAS) for pain and satisfaction were analyzed at minimum 2-year follow-up. In addition, all patients completed an RTS survey.

RESULTS

A total of 41 patients with a mean age and body mass index (BMI) of 29.6 ± 13.4 years and 25.3 ± 5.6, respectively, were included. Mean LCEA and Tönnis angle for the study population were 22.7°± 1.8° and 13.3°± 2.9°, respectively. A total of 31 (75.6%) patients were able to RTS after hip arthroscopy at a mean of 8.3 ± 3.2 months. A total of 14 patients (45.2%) were able to RTS at the same level of activity, 16 patients (51.6%) returned to a lower level of activity, and only 1 (3.2%) patient returned to a higher level of activity. Of the 11 high school and collegiate athletes, 10 (90.9%) were able to RTS. All patients demonstrated significant improvements in all patient-reported outcome measures (PROMs) as well as in pain scores at a mean of 26.1 ± 5.4 months after surgery. Patients who were able to RTS had a lower preoperative BMI than patients who did not RTS. Analysis of minimum 2-year PROMs demonstrated better HOS-ADL, HOS-SS, mHHS, iHOT-12, and VAS outcomes for pain in patients able to RTS versus those who did not RTS (P < .05).

CONCLUSION

Of the patients with BHD studied here, 75.6% of patients successfully returned to sport at a mean of 8.3 ± 3.2 months after hip arthroscopy for FAIS. Of the patients who successfully returned to sport, 45.2% returned at the same level, and 3.2% returned at a higher activity level.

Quantification of Acetabular Coverage on 3-Dimensional Reconstructed Computed Tomography Scan Bone Models in Patients With Femoroacetabular Impingement Syndrome: A Descriptive Study

Background

Accurate assessment of osseous morphology is imperative in the evaluation of patients with femoroacetabular impingement syndrome (FAIS) and hip dysplasia. Through use of computed tomography (CT), 3-dimensional (3D) reconstructed hip models may provide a more precise measurement for overcoverage and undercoverage and aid in the interpretation of 2-dimensional radiographs obtained in the clinical setting.

Purpose

To describe new measures of acetabular coverage based on 3D-reconstructed CT scan bone models.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

Preoperative CT scans were acquired on the bilateral hips and pelvises of 30 patients before arthroscopic surgical intervention for FAIS. Custom software was used for semiautomated segmentation to generate 3D osseous models of the femur and acetabulum that were aligned to a standard coordinate system. This software calculated percentage of total acetabular coverage, which was defined as the surface area projected onto the superior aspect of the femoral head. The percentage of coverage was also quantified regionally in the anteromedial, anterolateral, posteromedial, and posterolateral quadrants of the femoral head. The acetabular clockface was established by defining 6 o'clock as the inferior aspect of the acetabular notch. Radial coverage was then calculated along the clockface from the 9-o'clock to 5-o'clock positions.

Results

The study included 20 female and 10 male patients with a mean age of 33.6 ± 11.7 years and mean body mass index of 27.8 ± 6.3. The average percentage of total acetabular coverage for the sample was 57% ± 6%. Acetabular coverages by region were as follows: anteromedial, 78% ± 7%; anterolateral, 18% ± 7%, posterolateral, 33% ± 13%, and posteromedial, 99% ± 1%. The acetabular coverage ranged from 23% to 69% along the radial clockface from 9 to 5 o'clock.

Conclusion

This study demonstrated new 3D measurements to characterize acetabular coverage in patients with FAIS and elucidated the distribution of acetabular coverage according to these measurements.

Arthroscopic Management of Femoroacetabular Impingement in Adolescents: A Systematic Review

BACKGROUND

Femoroacetabular impingement (FAI) is highly prevalent in adolescent athletes. There has been an increasing trend for arthroscopic surgery for FAI, and the results of several clinical studies on outcome after arthroscopic surgery for FAI are available.

PURPOSE

To conduct a systematic review to investigate the role of arthroscopic management for FAI in adolescents.

STUDY DESIGN

Systematic review.

METHODS

This systematic review was conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. In August 2020, PubMed, Scopus, Google Scholar, and EMBASE were accessed. All clinical trials concerning the arthroscopic treatment for adolescents with FAI were identified. Only studies on patients aged less than 18 years at the time of surgery reporting data over a minimum follow-up of 12 months were considered.

RESULTS

Data from 406 adolescents (470 procedures; mean age at surgery, 15.9 years; mean follow-up, 30.4 months) with FAI were retrieved. At a mean of 28.0 months of follow-up, 94% of the adolescents had already returned to sport. All the scores of interest were improved at the final follow-up: visual analog scale (P = .01), modified Harris Hip Score (P < .0001), Non-Arthritic Hip Score (P = .03), Hip Outcome Score-Activities of Daily Living (P = .01), Hip Outcome Score-Sport-Specific Subscale (P < .0001), and Tegner score (P < .0001). Complications occurred in 1.1% (5/470) of procedures, and revision arthroscopy was performed in 4.7% (22/470) of procedures.

CONCLUSION

Arthroscopic surgery in adolescents with FAI achieves excellent outcomes and a high rate of return to sport, with rates of complication and revision surgery of 1% and 5%, respectively.

The Natural Course of Recovery After Hip Arthroscopy for Femoroacetabular Impingement According to the International Hip Outcome Tool-12 and Hip Outcome Score Sports Subscale

BACKGROUND

A paucity of literature exists regarding trajectories of functional and sports-specific recovery after hip arthroscopy for femoroacetabular impingement syndrome (FAIS).

PURPOSE

To determine if subgroups of patients exist based on the recovery trajectory of patient-reported outcomes (PROs) after hip arthroscopy for FAIS in the short-term period and to determine clinical predictors for these subgroups of patients.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

A prospectively maintained repository was queried for patients who had undergone primary hip arthroscopy for the treatment of FAIS between January 2012 and May 2018. Patients who completed the preoperative, 1-year, and 2-year International Hip Outcome Tool-12 (iHOT-12) or the Hip Outcome Score Sports Subscale (HOS-SS) were included. The latent class growth analysis (LCGA) and growth mixture models (GMMs) were used to identify subgroups of patients based on trajectories of recovery for the iHOT-12 and the HOS-SS utilizing preoperative, 1-year, and 2-year follow-ups. LCGA and GMM models using 1 to 6 classes for each PRO were performed, and the best-fit model for each PRO was selected. After final model selection, a multivariable multinomial logistic regression was performed, with the largest class being the reference group to determine clinical predictors of subgroup membership.

RESULTS

A total of 443 and 556 patients were included in the iHOT-12 and HOS-SS analyses, respectively. For the iHOT-12, we identified the following 3 subgroups: early progressors (70%), late regressors (22.3%), and late progressors (7.7%). Predictors of late regression were workers' compensation status, psychiatric history, preoperative chronic pain, and lower preoperative iHOT-12 scores; and late progressors were less likely to participate in sports. For the HOS-SS, we identified the following 4 subgroups: early progressors (47.7%), late regressors (17.4%), late progressors (6.8%), and steady progressors (28.1%). Predictors of less favorable recovery trajectories (late regressors and late progessors) were older age, male sex, back pain, psychiatric history, preoperative chronic pain, greater alpha angle, and lower preoperative HOS-SS scores.

CONCLUSION

Using the growth mixture modeling, 3 natural courses of health-related quality of life (early progression, late regression, and late progression) and 4 natural courses of recovery of athletic function (steady progression, late regression, late progression, and early progression) were identified. Preoperative psychiatric conditions, chronic pain, workers' compensation status, and lower iHOT-12 scores were predictive of less than favorable trajectories of recovery according to the iHOT-12, and male sex, older age, back pain, preoperative narcotic use, and lower preoperative HOS-SS were predictors of less favorable recovery trajectories according to the HOS-SS.

Impaired Lower Extremity Biomechanics, Hip External Rotation Muscle Weakness, and Proximal Femoral Morphology Predict Impaired Single-Leg Squat Performance in People With FAI Syndrome

BACKGROUND

Impairments in squat depth have been reported in patients with femoroacetabular impingement syndrome (FAIS). However, little is known about single-leg squat (SLS) performance in these patients, despite this task being commonly used in the rehabilitation and training settings.

PURPOSE/HYPOTHESIS

The aims of this study were (1) to investigate whether patients with FAIS demonstrate differences in SLS performance compared with healthy controls and (2) to determine whether dynamic range of motion (ROM), muscle strength, hip morphologic measures, hip pain, and hip-specific function predict SLS performance in patients with FAIS. We hypothesized that patients with FAIS would demonstrate impaired SLS performance and that impaired hip biomechanics, muscle strength, and hip-specific function would predict squat performance in patients with FAIS.

STUDY DESIGN

Controlled laboratory study.

METHODS

Three-dimensional (3D) kinematic data were collected at 100 Hz using a 20-camera 3D motion capture system during 3 SLS trials in 34 patients with FAIS and 26 healthy controls. Isometric muscle strength was tested with a stationary handheld dynamometer in all participants. Squat performance was quantified by squat depth (in meters), and the biomechanical variables of dynamic ROM of the pelvis, the hip, the knee, and the ankle in all planes were calculated. In patients with FAIS, femoral and acetabular morphology were measured using radiographic alpha angles and lateral center-edge angles. Hip pain and hip-specific function were measured using the visual analog scale for pain and the Hip Outcome Score Activities of Daily Living subscale, respectively. Two-tailed independent-samples t tests were used to determine between-group differences for squat depth, dynamic ROM variables, and muscle strength. A hierarchical multiple linear regression (MLR) model was used to determine whether biomechanical variables, muscle strength, hip morphology measures, hip pain, and hip-specific function were predictors of squat depth. All statistical analyses were performed using SPSS Version 26.

RESULTS

There were no between-group differences in age (FAIS, 30.0 ± 7.0 years vs controls, 27.3 ± 7.0 years; P = .18) or body mass index (FAIS, 23.1 ± 2.8 vs controls, 22.6 ± 3.2; P = .51). Squat depth was less in patients with FAIS compared with healthy controls (FAIS, 0.24 ± 0.4 m vs controls, 0.29 ± 0.05 m; P < .001). In the sagittal plane, patients with FAIS demonstrated less dynamic ROM of the hip (FAIS, 67.8°± 12.4° vs controls, 79.2°± 12.5°; P = .001) and the knee (FAIS, 71.9°± 9.4° vs controls, 78.9°± 13.2°; P = .02) compared with controls. Patients with FAIS also demonstrated a less dynamic coronal plane pelvis ROM (FAIS, 11.3°± 5.0° vs controls, 14.4°± 6.7°; P = .044). Patients with FAIS had reduced hip muscle strength of the hip external rotator (FAIS, 1 ± 0.3 N/kg vs controls, 1.2 ± 0.3 N/kg; P = .034), hip internal rotator (FAIS, 0.8 ± 0.3 N/kg vs controls 1 ± 0.3 N/kg; P = .03), and hip flexor (FAIS, 4 ± 1.1 N/kg vs controls, 4.8 ± 1.2 N/kg; P = .013) muscle groups. The hierarchical MLR revealed that the dynamic ROM of the hip, the knee, and the pelvis, the hip external rotation muscle strength, and the femoral alpha angles were all significant predictors of squat performance, and the final MLR model explained 92.4% of the total variance in squat depth in patients with FAIS.

CONCLUSION

Patients with FAIS demonstrate impaired SLS squat performance compared with healthy controls. This impaired squat performance is predominantly predicted by sagittal plane knee and hip biomechanics and hip external rotator strength, and less by frontal plane pelvic ROM and hip morphology in patients with FAIS.

CLINICAL RELEVANCE

Clinicians should focus treatment on improving dynamic ROM and hip external rotator muscle strength to improve squat performance; however, femoral morphology should also be considered in the treatment paradigm.

Analysis of morphological parameters in pelvic radiography and hip MRI : a practical reporting recommendation

Although numerous criteria have been proposed to define abnormal hip morphology, mostly used in the diagnosis of femoroacetabular impingement, it is not a practical approach to measure all of these parameters in all cases without clinical suspicion. In this study, our aim was to develop an evaluating and reporting standardization for routine hip examinations to define both hip morphology and impingement. A total of 108 patients with routine hip magnetic resonance imaging (MRI) and antero-posterior pelvic radiograph (PR) were included in this retrospective study. Alpha angle (AA), acetabular depth (AD), acetabular protrusion, acetabular anteversion, collo- diaphyseal angle (CDA), lateral center-edge angle (LCEA) and Tönnis angle (TA) were measured. The differences and associations between these parameters were evaluated according to imaging modality or plane, and sex. Although a significant difference has been found between the axial AA and the coronal AA mean values measured on MRI, there was also a strong correlation. Coronal measurements were significantly higher. AA values measured in PR and coronal MRI were comparable. Males had higher AA in both planes as compared to females. There were no significant differences between CDA values in MRI and PR. There was a significant difference and a moderate correlation between AD values in MRI and PR. We suggest that routine reports should include a measurement of AA in two planes, and measurement of CDA in PR or MRI. Due to the difference in AD between MRI and radiography, LCEA or TA may represent better alternatives. Checking for a negative Tönnis sign would represent a practical approach.

The Role of Imaging in Femoroacetabular Impingement: History, Current Practices, and Future Applications

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Femoroacetabular impingement (FAI) is one of the most common causes of early hip articular cartilage wear and labral damage, and subsequently leads to the onset of hip osteoarthritis.

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Cam-type FAI impingement lesions can be best identified with a 90° Dunn lateral radiograph and a cross-table lateral radiograph with 15° of internal rotation; the alpha angle and the femoral head-neck offset are the most used predictive radiographic markers.

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FAI lesions with pincer impingement are associated with acetabular retroversion and are more difficult to identify on traditional radiographic imaging; however, the presence of a crossover sign, an ischial spine sign, and/or a posterior wall sign can be useful radiographic markers.

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Advanced imaging modalities such as magnetic resonance imaging (MRI) and/or magnetic resonance arthrography (MRA) can also be beneficial in the evaluation of FAI and labral pathology; MRA is more sensitive than MRI in detecting intra-articular pathology.

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Computer-assisted navigation for preoperative planning and intraoperative surgical assistance are promising technologies; however, additional studies are needed before they can be utilized safely and effectively.

The lateral joint space width is essential for the outcome after arthroscopically assisted mini-open arthrotomy for treatment of a femoroacetabular impingement: an analysis of prognostic factors for the success of this hip-preserving technique

PURPOSE

The purpose of this study was to analyze predicting factors for a conversion to a total hip replacement (THR) after mini-open arthrotomy for treatment of femoroacetabular impingement (FAI).

METHODS

Between 2011 and 2016, we identified 32 patients, who were treated for FAI with a mini-open arthrotomy and received after mean time of 2.1 ± 1.4 years a THR. These patients were compared to 47 cases who did not receive a THR (mean follow-up: 4.3 ± 0.7 years) to explore pre- and intra-operative factors associated with a conversion to THR. The results were presented in separated Kaplan-Meier curves with log rank test for significance and hazard ratios.

RESULTS

A lateral joint space width of > 4 mm showed a higher THR-free survival rate compared to < 4 mm (p = 0.001); analogously one-sided (acetabular/femoral) 3-4° cartilage damage had a comparable THR-free survival rate than 1-2° kissing lesions (p = 0.001). Furthermore, an intact labrum without treatment and good cartilage status, a refixed labrum after rim resection in case of a pincer type FAI, or a refixed teared labrum were associated with a longer THR-free time than an untreated labrum accompanied by a poor cartilage status or an ossified labrum (p = 0.002). The strongest independent factor for a conversion to THR was femoral cartilage damage grade 1 and higher (p = 0.046). However, the rate of available patients was 53.0%.

CONCLUSION

The success of a joint-preserving mini-open arthrotomy seems to be dependent on the status of the radiological joint space width and the intra-operative cartilage status of the lateral edge.

Femoroacetabular impingement: correlation between imaging parameters, sport activity, and chondral damage

BACKGROUND

Femoroacetabular impingement is characterised by an abnormal contact between the acetabulum and the femoral head-neck junction. Femoroacetabular impingement shows three main clinical frameworks: Pincer-FAI, Cam-FAI and Cam-Pincer mixed form. The aim of the study was to investigate the correlation between femoroacetabular impingement, imaging, activity and chondral damages.

METHODS

Forty-one patients, undergoing arthroscopic chondroartroplasty for Cam and Cam-Pincer mixed form were considered. All patients underwent an X-ray hip evaluation (G1 group), while 15 patients also underwent a pelvis MRI evaluation (G2 subgroup). For G1 patients, the superior-inferior offset ratio and alpha angle were calculated from the X-ray examinations. For G2 patients, the antero-posterior offset ratio was also calculated from pelvis MRI. Chondral damage was classified according to the Outerbridge classification.

RESULTS

The superior-inferior offset ratio and the antero-posterior offset ratio were respectively 0.50 ± 0.23 and 0.33 ± 0.19. The α angle predictive for a chondral damage of IV degree was 81.5°.The chondral damage of the patients suffering from Cam-FAI and Cam-Pincer mixed form were respectively 3.53±0.80 and 3.00±1.41.

CONCLUSIONS

From the results was possible to: - Elaborate two tables providing a reliable indirect calculation of the alpha angle. - Establish an alpha angle cut-off value indicative for a IV degree chondral damage. - Show that Pincer-FAI does not represent an aggravating factor for chondral damage - Show that the level of sports activity was related to the severity of chondral damage. - Show that a physically demanding occupation was not an aggravating factor for chondral damage.

Surgical Treatment of Labral Tears: Debridement, Repair, and Reconstruction

Advances in hip preservation surgery have to lead to increased utilization of hip arthroscopy. With this, there has also been a growth in the understanding of various hip conditions, therefore, leading to an increase in hip conditions amenable to arthroscopic intervention. The acetabular hip labrum has been at the forefront of arthroscopic advances in the hip. The labrum is important for hip stability, provision of the suction seal, and joint proprioception. Given the labrum's central role in hip biomechanics, there is increasing emphasis on labral preservation in the form of debridement and repair. In revision settings, advanced techniques such as labral augmentation and reconstruction may play a role in the management of labral pathology. Appropriate management of the hip labrum at the time of surgery can be an important mediator of the outcome. As such, an understanding of the evolving evidence base and surgical indications and techniques are integral to the treatment and management of labral pathology.

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.

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Advances in FAI Imaging: a Focused Review

PURPOSE OF REVIEW

Femoroacetabular impingement (FAI) is one of the main causes of hip pain in young adults and poses clinical challenges which have placed it at the forefront of imaging and orthopedics. Diagnostic hip imaging has dramatically changed in the past years, with the arrival of new imaging techniques and the development of magnetic resonance imaging (MRI). This article reviews the current state-of-the-art clinical routine of individuals with suspected FAI, limitations, and future directions that show promise in the field of musculoskeletal research and are likely to reshape hip imaging in the coming years.

RECENT FINDINGS

The largely unknown natural disease course, especially in hips with FAI syndrome and those with asymptomatic abnormal morphologies, continues to be a problem as far as diagnosis, treatment, and prognosis are concerned. There has been a paradigm shift in recent years from bone and soft tissue morphological analysis towards the tentative development of quantitative approaches, biochemical cartilage evaluation, dynamic assessment techniques and, finally, integration of artificial intelligence (AI)/deep learning systems. Imaging, AI, and hip preserving care will continue to evolve with new problems and greater challenges. The increasing number of analytic parameters describing the hip joint, as well as new sophisticated MRI and imaging analysis, have carried practitioners beyond simplistic classifications. Reliable evidence-based guidelines, beyond differentiation into pure instability or impingement, are paramount to refine the diagnostic algorithm and define treatment indications and prognosis. Nevertheless, the boundaries of morphological, functional, and AI-aided hip assessment are gradually being pushed to new frontiers as the role of musculoskeletal imaging is rapidly evolving.

Importance of Retaining Sufficient Acetabular Depth: Successful 2-Year Outcomes of Hip Arthroscopy for Patients With Pincer Morphology as Compared With Matched Controls

BACKGROUND

Patients with pincer-type femoroacetabular impingement are commonly treated with arthroscopic reduction of acetabular depth as measured by the lateral center-edge angle (LCEA). The optimal amount of rim reduction has not been established, although large resections may increase contact pressures through the hip. A recent publication demonstrated inferior surgical outcomes in patients with acetabular overcoverage as compared with normal acetabular coverage. Casual observation of our database suggested equivalent improvements, prompting a similar analysis.

PURPOSE

To analyze patient-reported outcomes after hip arthroscopy for femoroacetabular impingement in patients with acetabular overcoverage who were matched with controls with normal coverage, as well as to analyze associations with reduction in LCEA.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Data were collected prospectively from patients with a minimum 2-year follow-up after receiving hip arthroscopy for femoroacetabular impingement by a single surgeon. Cases were reviewed to identify those with pincer-type morphology (LCEA >40°) and matched according to sex, age, chondral damage, and surgery date in a 1:1 ratio with controls with an LCEA of 25° to 40°. The surgical goal was to reduce the LCEA to the upper end of the normal range with minimal rim resection, usually 35° to 37°. Radiographic measurements of coverage, intraoperative findings, procedures, and patient-reported outcomes were recorded, including the 12-Item International Hip Outcome Tool, Non-arthritic Hip Score, Hip Disability and Osteoarthritis Outcome Score, visual analog scale for pain, rates of revision or reoperation, and conversion to total hip arthroplasty.

RESULTS

A total of 114 hips (93 patients) for the pincer group were matched 1:1 from 616 hips (541 patients) for the control group. The pincer group (mean ± SD age, 34.5 ± 12.2 years) did not differ in age, body mass index, or follow-up from controls. LCEA was reduced in both groups pre- to postoperatively: the pincer group from 44.0° ± 2.8° to 34.2° ± 3.5° and the controls from 32.9° ± 3.9° to 31.0° ± 3.0°. No differences in improvement were observed: iHOT-12 improved by 35.7 points in both groups (P = .9 for analysis of variance interaction) and Nonarthritic Hip Score by 22.3 points (P = .6). From all eligible surgical procedures, 2-year follow up rates were 2.5% and 2.6% for the pincer and control cohorts, respectively, and 1.2% and 0.3% for conversion to total hip arthroplasty.

CONCLUSION

Arthroscopic management of acetabular overcoverage can achieve excellent results, equivalent to arthroscopy for other causes of symptomatic femoroacetabular impingement. A key finding was smaller rim resections producing a mean postoperative LCEA of 34.2° with a small standard deviation.

Patient-related risk factors associated with less favourable outcomes following hip arthroscopy

AIMS

This paper aims to review the evidence for patient-related factors associated with less favourable outcomes following hip arthroscopy.

METHODS

Literature reporting on preoperative patient-related risk factors and outcomes following hip arthroscopy were systematically identified from a computer-assisted literature search of Pubmed (Medline), Embase, and Cochrane Library using Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines and a scoping review.

RESULTS

Assessment of these texts yielded 101 final articles involving 90,315 hips for qualitative analysis. The most frequently reported risk factor related to a less favourable outcome after hip arthroscopy was older age and preoperative osteoarthritis of the hip. This was followed by female sex and patients who have low preoperative clinical scores, severe hip dysplasia, altered hip morphology (excess acetabular retroversion or excess femoral anteversion or retroversion), or a large cam deformity. Patients receiving workers' compensation or with rheumatoid arthritis were also more likely to have a less favourable outcome after hip arthroscopy. There is evidence that obesity, smoking, drinking alcohol, and a history of mental illness may be associated with marginally less favourable outcomes after hip arthroscopy. Athletes (except for ice hockey players) enjoy a more rapid recovery after hip arthroscopy than non-athletes. Finally, patients who have a favourable response to local anaesthetic are more likely to have a favourable outcome after hip arthroscopy.

CONCLUSION

Certain patient-related risk factors are associated with less favourable outcomes following hip arthroscopy. Understanding these risk factors will allow the appropriate surgical indications for hip arthroscopy to be further refined and help patients to comprehend their individual risk profile. Cite this article: Bone Joint J 2020;102-B(7):822-831.

Lateral Center-Edge Angle Is Not Predictive of Acetabular Articular Cartilage Surface Area: Anatomic Variation of the Lunate Fossa

BACKGROUND

Surgical treatment of symptomatic femoroacetabular impingement (FAI) and dysplasia requires careful characterization of acetabular morphology. The lateral center-edge angle (LCEA) is often used to assess lateral acetabular anatomy. Previous work has questioned the LCEA as a surrogate for acetabular contact/articular cartilage surface area because of the variable morphology of the lunate fossa.

HYPOTHESIS

We hypothesized that weightbearing articular cartilage of the acetabulum would poorly correlate with LCEA secondary to significant variation in the size of the lunate fossa.

STUDY DESIGN

Cohort study (Diagnosis); Level of evidence, 3.

METHODS

Patients with 3D CT imaging undergoing either hip arthroscopy or periacetabular osteotomy for FAI or symptomatic hip instability were retrospectively identified. The LCEA and femoral head diameter were measured on an anteroposterior pelvis radiograph. Patients were grouped according to their lateral acetabular coverage as undercoverage (LCEA, <25°), normal coverage (LCEA, 25°-40°), or overcoverage (LCEA, >40°). Patients were randomly identified until each group contained 20 patients. The articular surface area was measured from preoperative 3D CT data. Linear regression analysis was performed to examine the relationship between articular surface area and LCEA. Continuous and categorical data were analyzed utilizing analysis of variance and chi-square analysis. Statistical significance was set at P < .05.

RESULTS

No difference in age (P = .52), body mass index (BMI) (P = .75), or femoral head diameter (P = .66) was noted between groups. A significant difference in articular surface area was observed between patients with undercoverage and those with overcoverage (20.4 cm² vs 24.5 cm²; P = .01). No significant difference was identified between the undercoverage and normal groups (20.4 cm² vs 23.3 cm²; P = .09) or the normal and overcoverage groups (23.3 cm² vs 24.5 cm²; P = .63). A moderate positive correlation was observed between LCEA and articular surface area across all patients (r = 0.38; P = .002) but not when patients with undercoverage were excluded (r = 0.02; P = .88). Significant variation in surface area was observed within each group such that no patient in any group was outside of 2 SDs of the means of the other groups. When patients were categorized into quartiles established by the articular surface area for the entire population, 40% of patients with overcoverage were observed in the first or second quartile (lower area).

CONCLUSION

Lateral acetabular undercoverage based on the LCEA (<25°) correlates with decreased acetabular surface area. Normal or increased acetabular coverage (LCEA, >25°), however, is not predictive of increased, normal, or decreased acetabular surface area.

Mirror Image Modeling of Acetabular Rim Thickness Differences in Patients With Unilateral Femoroacetabular Impingement Syndrome

Purpose

To use mirror imaging to identify the location and magnitude of difference in acetabular rim morphology between the symptomatic and unaffected acetabula in patients with symptomatic unilateral pincer-type or mixed femoroacetabular impingement syndrome (FAIS) using 1-dimensional models created with computed tomography (CT).

Methods

CT scans of bilateral hips in 33 patients diagnosed with unilateral pincer-type or mixed FAIS were obtained. Three-dimensional bilateral hip models were constructed, and the unaffected hemipelvis was superimposed onto the symptomatic side to compare acetabular thickness. Protrusion of the symptomatic side was recorded, and rim morphology was divided into clock face quadrants to analyze the location of greatest magnitude of difference between affected and unaffected acetabula. Analysis of the quadrants was performed using analysis of variance with post hoc Bonferroni correction.

Results

The study group consisted of more females (51.6%) than males, with an average age of 35.72 ± 7.8 years and an average body mass index of 24.3 ± 4.1 kg/m². Of the 33 hips included, 14 were isolated pincer-type FAIS and 19 were mixed. The average preoperative symptomatic side lateral center edge angle was 37.5° ± 7.2° compared with 29° ± 5.1° on the asymptomatic side (P = .001). The symptomatic acetabular rim was on average 0.43 ± 0.18 mm thicker than the corresponding location on the unaffected rim. When the acetabulum was divided into clock face quadrants, the 12 to 3 o'clock position showed the greatest difference between symptomatic and unaffected sides (0.55 ± 0.18 mm) compared with the 3 to 6 o'clock position (0.4 ± 0.28 mm; P = .006), 6 to 9 o'clock (0.34 ± 0.07 mm; P < .001), and 9 to 12 o'clock (0.38 ± 0.03; P = .001).

Conclusions

Patients with unilateral, symptomatic pincer-type or mixed FAIS show statistical differences in rim thickness between the affected and unaffected acetabula. Small changes in acetabular rim morphology on the order of ≤0.5 mm may be the difference between symptomatic FAIS and the unaffected hip.

Level of Evidence

IV, case series.

Clinical and Radiographic Aspects of Patients with Femoroacetabular Impingement Syndrome: Is There Difference between Symptomatic and Asymptomatic Hip?

Objective  This paper aims to compare clinical and radiographic features of symptomatic and asymptomatic hips in patients with unilateral femoroacetabular impingement syndrome (FAIS) and to establish a correlation between these findings. Methods  This is a retrospective study, based on medical records of patients diagnosed with FAIS between January 2014 and April 2017. The patients were assessed clinically as per the International Hip Outcome Tool 33 (iHOT33) questionnaire, visual analogue pain scale, hip rotation, and hip and knee muscular strength. The radiographic evaluation consisted of measurements of the alpha angle, crossover signal, acetabular retroversion index, ischial spine signal, and posterior wall sign. Results  A total of 45 patients were included in the study, with mean time from symptom onset to diagnosis of 28.6 months and mean iHOT33 score was 39.9. The mean medial rotation was 20.5° in symptomatic hip and 27.2° in asymptomatic hip ( p  < 0.001). The crossover signal was positive on 68.9% of the symptomatic hips and 55.6% of the asymptomatic hips ( p  = 0.03). The mean retroversion index was 0.15 in symptomatic hips and 0.11 in asymptomatic hips ( p  = 0.02). There was a positive correlation between the total time of symptoms and medial hip rotation reduction ( p  = 0.04) and between body mass index (BMI) and medial hip rotation reduction ( p  = 0.02). Conclusion  When comparing clinical and radiographic features, we observed reduction of medial rotation and increase of acetabular retroversion index in the symptomatic hip, as well as association between the long symptom time and the high BMI with loss of medial rotation of the hips.

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.

Diagnostic sensitivity and specificity of dynamic three-dimensional CT analysis in detection of cam and pincer type femoroacetabular impingement

Background

Cam and pincer-type morphologies can cause femoroacetabular impingement syndrome (FAI) and can be measured on plain radiographs using the alpha angle and the center edge angle. As an addition to plain radiographs and to assess femoroacetabular impingement, it is possible to visualize the interplay of the acetabular and femoral morphology by means of dynamic three-dimensional simulation of hip joint. Therefore, the objective of this study is to compare alpha angles and center edge angles on plain radiographs with the dynamic computerized tomography (CT) analysis in patients with complaints of femoroacetabular impingement.

Methods

All patients from our prospective cohort from 2012 to 2015 who underwent radiographs and a dynamic CT analysis for FAI were selected. Cam type morphologies were measured with the alpha angle and pincer type morphologies with lateral center-edge angle on radiographs and with CT analysis. The dynamic CT analysis also calculated position and size of impingement of femur and acetabulum. Intra-operative assessment was used to confirm impingement. Sensitivity, specificity and predictive values were calculated compared with respect to the intra-operative assessment.

Results

A total of 127 patients were included. 90 cam morphologies and 45 pincer morphologies were identified intra-operatively.

The sensitivity and specificity for cam morphology measured with radiographs was 84 and 72% compared to 90 and 43% with three dimensional dynamic analyses. The sensitivity and specificity for pincer morphology measured with radiographs was 82 and 39% compared to 84 and 51% with three dimensional dynamic analyses.

Conclusions

Diagnostic accuracy is comparable in three-dimensional dynamic analysis of CT scans and radiographs representing FAI caused by cam or pincer type morphology.

Level of evidence

IV

Professional soccer is associated with radiographic cam and pincer hip morphology

PURPOSE

Femoroacetabular impingement (FAI) syndrome is characterized by a triad: symptoms, clinical signs and imaging findings. Some individuals, especially athletes, have only imaging alterations. The objective of this study was to evaluate the prevalence of cam and pincer morphology in professional soccer players compared with a control group of non-athletes and to investigate the association between the age at which players start playing competitive soccer more than three times per week and duration of the soccer career with the prevalence of these radiographic findings.

METHODS

The prevalence of cam and pincer morphology in sixty professional adult male soccer players and thirty-two male controls was determined using pelvic anteroposterior radiography. Data were recorded for all hips and correlated with the age at which the players started competitive soccer practice and with the duration of their soccer career.

RESULTS

The prevalence of morphological FAI in the soccer players was 92.5% versus 28.1% in the controls (p < 0.001). The duration of the soccer career was positively correlated with the alpha angle (p = 0.033) and negatively correlated with the retroversion index (p = 0.009). The age at which competitive play began was inversely correlated with the alpha angle (p < 0.001).

CONCLUSION

The study showed a high prevalence of cam and pincer morphology in Brazilian professional soccer players compared with controls. The duration of the soccer career was associated with an increased alpha angle and a decreased retroversion index, and the age at which competitive soccer participation began was negatively associated with alpha angle values. Finally, this manuscript provides data about the association between greater exposure to soccer and cam and pincer morphological changes in the hip; specifically, cam morphology was more common in patients who began participating in sports at earlier ages. This information serves as an alert for coaches of youth teams to manage the training load in youth athletes.

LEVEL OF EVIDENCE

III.

Management of femoroacetabular impingement syndrome: current insights

Since the description of femoroacetabular impingement (FAI) by Ganz in 2003, our understanding of the pathophysiology, management options, and outcomes has evolved and literature continues to be generated on this condition at a rapid rate. FAI has been identified as a primary source of hip pain as well as a generator of secondary osteoarthritis. Improvements in the radiographic detection of cam and pincer morphologies as well as a better understanding of the structural impact of these morphologies have led to improved preoperative planning. Advancements in hip arthroscopy techniques have also led to a higher rate of arthroscopic management of this condition over the initially described open surgical dislocation technique. While arthroscopic management of this condition has become the most common form of surgical management for FAI, inadequate bony resection has been shown to be a frequent source of revision surgery. Therefore, roles for open surgical dislocation and combined mini-open approaches remain, particularly in cases where concern for the inability to fully access the morphology arthroscopically exists.

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.

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

BACKGROUND

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

PURPOSE

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

STUDY TYPE

Case-control study.

POPULATION

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

FIELD STRENGTH/ SEQUENCE

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

ASSESSMENT

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

STATISTICAL TESTS

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

RESULTS

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

DATA CONCLUSION

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

LEVEL OF EVIDENCE

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

Prevalence of High-Grade Cartilage Defects in Patients With Borderline Dysplasia With Femoroacetabular Impingement: A Comparative Cohort Study

PURPOSE

To compare the prevalence, size, and location of Outerbridge grade III and IV cartilage defects on the femoral head and acetabulum between patients with borderline acetabular dysplasia and patients with non-borderline dysplasia who underwent hip arthroscopy for femoroacetabular impingement (FAI).

METHODS

Patients aged 18 years or older who underwent primary hip arthroscopy for correction of FAI and labral repair from November 2005 to April 2016 were included. We excluded patients with previous hip surgery, a radiographic hip joint space of 2 mm or less, and/or a lateral center-edge angle (LCEA) of less than 20° or greater than 40°. The study patients were divided into 2 groups based on the LCEA on the anteroposterior pelvic radiograph: Patients with an LCEA between 20° and 25° were included in the borderline group, and patients with an LCEA between 25° and 40° were included in the non-borderline group. The prevalence, size, and location of Outerbridge grade III and IV chondral lesions on the femoral head and acetabulum were recorded intraoperatively. Comparisons between groups were performed with the Mann-Whitney U test for nonparametric testing and the t test for data that were normally distributed. Data were analyzed to calculate odds ratios associated with the various factors.

RESULTS

In total, 2,429 patients (1,114 women and 1,315 men) met the inclusion criteria. The borderline group consisted of 305 patients (150 men and 155 women), whereas the non-borderline dysplasia group comprised 2,124 patients (1,165 men and 959 women). Outerbridge grade III and IV chondral lesions were found on the femoral head in 118 patients with borderline dysplasia (39%) and 127 patients with non-borderline dysplasia (6%) and on the acetabulum in 132 patients with borderline dysplasia (43%) and 874 patients with non-borderline dysplasia (41%). Patients with borderline dysplasia were 10 times more likely (95% confidence interval, 7.3-13.4; P < .001) to have a grade III or IV cartilage defect on the weight-bearing surface of the femoral head (P < .001) than patients with non-borderline dysplasia. On the acetabular side, no difference in the prevalence of severe cartilage damage was detected between the 2 groups (P = .588). The size of chondral damage was significantly greater in patients with borderline dysplasia on the acetabulum (P = .039) compared with the non-borderline dysplasia group.

CONCLUSIONS

Patients with FAI and borderline dysplasia are at higher risk of having Outerbridge grade III and IV chondral damage on the femoral head than patients with non-borderline dysplastic hips. Borderline dysplastic hips also presented with significantly larger chondral defects on the acetabular surface.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Is There an Association Between Borderline-to-mild Dysplasia and Hip Osteoarthritis? Analysis of CT Osteoabsorptiometry

BACKGROUND

The definitive treatment of borderline-to-mild dysplasia remains controversial. A more comprehensive understanding of the etiology of osteoarthritis (OA) and clarification of any possible association between borderline-to-mild dysplasia and the pathogenesis of OA are essential.

QUESTIONS/PURPOSES

(1) Does the distribution of acetabular subchondral bone density increase according to dysplasia severity? (2) Is there an association between borderline-to-mild dysplasia and OA pathogenesis?

METHODS

We evaluated bilateral hips of patients with developmental dysplasia of the hip who underwent eccentric rotational acetabular osteotomy (ERAO) for inclusion in the dysplasia group and contralateral hips of patients with unilateral idiopathic osteonecrosis of the femoral head (ONFH) who underwent curved intertrochanteric varus osteotomy (CVO) for the control group. ERAO was performed in 46 patients and CVO was performed in 32 patients between January 2013 and August 2016 at our institution. All patients underwent bilateral hip CT. The study included 55 hips categorized according to dysplasia severity: (1) borderline-mild, 19 hips (15° ≤ lateral center-edge angle [LCEA] < 25°); (2) moderate, 20 hips (5° ≤ LCEA < 15°); (3) severe, 16 hips (LCEA < 5°); and (4) control, 15 hips. Thirty-seven dysplastic hips (age < 15 or > 50 years old, prior hip surgery, subluxation, aspherical femoral head, cam deformity, and radiographic OA) and 17 control hips (age < 15 or > 50 years old, bilateral ONFH, LCEA < 25° or ≥ 35°, cam deformity, and radiographic OA) were excluded. CT-osteoabsorptiometry (OAM) predicts physiologic biomechanical conditions in joints by evaluating subchondral bone density. We evaluated the distribution of subchondral bone densities in the acetabulum with CT-OAM, dividing the stress distribution map into six segments: anteromedial, anterolateral, centromedial, centrolateral, posteromedial, and posterolateral. We calculated the percentage of high-density area, which was defined as the upper 30% of Hounsfield units values in each region and compared least square means difference estimated by the random intercept model among the four groups.

RESULTS

In all regions, the percentage of high-density area did not differ between the borderline-mild group and the control (eg, anterolateral, 16.2 ± 5.6 [95% CI, 13.4 to 18.9] versus 15.5 ± 5.7 [95% CI, 12.4 to 18.5, p = 0.984]; centrolateral, 39.1 ± 5.7 [95% CI, 36.4 to 41.8] versus 39.5 ± 4.7 [95% CI, 36.6 to 42.5, p = 0.995]; posterolateral, 10.9 ± 5.2 [95% CI, 8.0 to 13.8] versus 15.1 ± 6.8 [95% CI, 11.7 to 18.5, p = 0.389]). In the anterolateral region, a smaller percentage of high-density area was observed in the borderline-mild group than in both the moderate group (16.2 ± 5.6 [95% CI, 13.4-18.9] versus 28.2 ± 5.1 [95% CI, 25.5-30.9], p < 0.001) and the severe group (16.2 ± 5.6 [95% CI, 13.4-18.9] versus 22.2 ± 6.8 [95% CI, 19.2-25.2, p = 0.026).

CONCLUSIONS

Our results suggest that the cumulative hip stress distribution in borderline-to-mild dysplasia was not concentrated on the lateral side of the acetabulum, unlike severe dysplasia.

CLINICAL RELEVANCE

Based on the stress distribution pattern, our results may suggest that there is no association between borderline-to-mild dysplasia and the pathogenesis of OA. Further studies are needed to evaluate the association between borderline-to-mild dysplasia and instability of the hip.

The Physiotherapy for Femoroacetabular Impingement Rehabilitation STudy (physioFIRST): A Pilot Randomized Controlled Trial

Study Design A pilot double-blind randomized controlled trial (RCT). Background The effectiveness of physical therapy for femoroacetabular impingement syndrome (FAIS) is unknown. Objectives To determine the feasibility of an RCT investigating the effectiveness of a physical therapy intervention for FAIS. Methods Participants were 17 women and 7 men (mean ± SD age, 37 ± 8 years; body mass index, 25.4 ± 3.4 kg/m²) with FAIS who received physical therapy interventions provided over 12 weeks. The FAIS-specific physical therapy group received personalized progressive strengthening and functional retraining. The control group received standardized stretching exercises. In addition, both groups received manual therapy, progressive physical activity, and education. The primary outcome was feasibility, including integrity of the protocol, recruitment and retention, outcome measures, randomization procedure, and sample-size estimate. Secondary outcomes included hip pain and function (international Hip Outcome Tool-33 [iHOT-33]) and hip muscle strength. Poststudy interviews were conducted to determine potential improvements for future studies. Results Twenty-four (100%) patients with known eligibility agreed to participate. Four patients (17%) were lost to follow-up. All participants and the tester remained blinded, and the control intervention was acceptable to participants. The between-group mean differences in change scores were 16 (95% confidence interval [CI]: -9, 38) for the iHOT-33 and 0.24 (95% CI: 0.02, 0.47) Nm/kg for hip adduction strength, favoring the FAIS-specific physical therapy group. Using an effect size of 0.61, between-group improvements for the iHOT-33 suggest that 144 participants are required for a full-scale RCT. Conclusion A full-scale RCT of physical therapy for FAIS is feasible. A FAIS-specific physical therapy program has the potential for a moderate to large positive effect on hip pain, function, and hip adductor strength. Level of Evidence Therapy, level 2b. J Orthop Sports Phys Ther 2018;48(4):307-315. doi:10.2519/jospt.2018.7941.