Prevalence of cam-type femoroacetabular impingement morphology in asymptomatic volunteers

Medium-term results of arthroscopic treatment for femoroacetabular impingement

INTRODUCTION

Femoroacetabular impingement (FAI) is a dynamic pathomechanical process of the femoral head-neck junction. Arthroscopic surgery for FAI has increased exponentially in the last decade, and this trend is expected to increase.

SOURCE OF DATA

Recent published literatures.

AREAS OF AGREEMENT

FAI promotes quick rehabilitation and low complication rates in the short-term follow-up.

AREAS OF CONTROVERSY

Despite the growing interest on arthroscopic surgery for FAI, current evidence regarding the medium- and long-term role of arthroscopy are unsatisfactory.

GROWING POINTS

Systematically summarize current evidences, analyse the quantitative available data and investigate the medium- and long-term outcomes of arthroscopic surgery for FAI.

AREAS TIMELY FOR DEVELOPING RESEARCH

Arthroscopic surgery achieves very satisfactory outcomes for patients with FAI at a mean follow-up of 4 years.

Characteristics of femoroacetabular impingement morphology and relation with skeletal maturity among asymptomatic adolescents

The aim of this study was to analyze presence of the morphological characteristics and prevalence of FAI in asymptomatic adolescents and assess the relation of skeletal maturation with development of FAI morphology. Abdominopelvic computed tomography (CT) of 265 adolescents (9-19 years old) who were admitted to the emergency department between 2011 and 2016 were evaluated retrospectively. Radial reformatted CT images from the femoral neck were created using the multiplanar reconstruction (MPR) method. The femoral neck was divided into 12 segments and alpha angle (AA), femoral head-neck ratio (FHNR) and center-edge angle (CEA) were measured from each segment. Additionally, images were evaluated for the physiological status (open or closed) of the triradiate- cartilage and proximal femoral epiphyses. 204 hips from 102 patients (32 females, 70 males) were retrospectively reviewed. There were 27 (26.5%) patients with cam-type morphology and 18 (17.6%) patients with pincer-type morphologies. No statistically significant difference was detected between the prevalences of cam and pincer morphologies between the two genders. Cam deformity was most frequently seen in anterosuperior segment. All of the patients (100%) with pincer-type morphology and 88% of the patients with cam-type morphology had closed triradiate cartilage, 89% of the patients with cam morphology and 83% with pincer morphology had open proximal femoral physis. Our results showed that prevalence of cam and pincer-type morphology in asymptomatic adolescents is similar to asymptomatic adults. Our findings also indicate that cam- and pincer-type FAI morphologies likely develop during late adolescence after closure of triradiate cartilage and before closure of proximal femoral physis. Level of Evidence - 3

Characterizing cam-type hip impingement in professional women's ice hockey players

OBJECTIVE

There is a high prevalence of femoroacetabular impingement (FAI) amongst elite men's ice hockey players, yet little is known about the hips of players in the National Women's Hockey League (NWHL). The primary purpose of this study was to determine the prevalence of radiographic cam-type FAI in women's professional ice hockey players. The secondary purpose was to analyze the relationship between the cam deformity and both menarchal age and hip range-of-motion (ROM).

METHODS

Data were collected for NWHL players during pre-participation physicals. Alpha angles were measured on 45° Dunn radiographs, with alpha angles >55° defined as cam-positive. Pearson correlation coefficients (ρ) were performed to analyze the relationship between alpha angle and both ROM measurements and menarchal age, with statistical significance set at p < 0.05.

RESULTS

Twenty-six athletes were included. Twenty-four (92%) had alpha angles >55°; 20 players (77%) had bilateral cam deformity. Average menarchal age was 13.8 ± 1.7 years. There was a significant association between age of menarche and alpha angle (ρ = 0.36, p < 0.02). There was no significant association between alpha angle and hip ROM (p > 0.05).

CONCLUSION

Elite women's ice hockey players have a higher prevalence of cam-type morphology than the general population. The positive association between alpha angle and menarchal age lends additional support to the etiological hypothesis of the cam lesion resulting from activity-related stress at the proximal femoral physis during skeletal development. Professional women's ice hockey players have a high risk of developing cam-type morphology, although each player's menarchal age may mediate her individual risk for cam development.

Femoroacetabular Impingement and Core Muscle Injury in Athletes: Diagnosis and Algorithms for Success

Athletic hip injuries account for a substantial portion of missed time from sports in high-level athletes. For both femoroacetabular impingement (FAI) and core muscles injuries, a thorough history and physical examination are paramount to guide the treatment. While advanced imaging including computed tomography and magnetic resonance imaging are frequently obtained, a wealth of information can be ascertained from standard radiographs alone. For patients with isolated or combined FAI and core muscle injuries (CMIs), the initial treatment is often nonoperative and consists of rest, activity modification, and physical therapy of the hips, core, and trunk. Injections may then aid in both confirming diagnosis and temporary symptom abatement. Arthroscopic procedures for refractory FAI in experienced hands have been shown to be both safe and efficacious. While surgical repair options for CMIs are significantly more variable, long-term studies have demonstrated the rapid resolution of symptoms and high return to play rates. More recently, anatomic and clinical correlations between FAI and CMIs have been identified. Special attention must be paid to elite athletes as the incidence of concurrent FAI with CMI is extremely high yet with significant symptom variability. Predictable return to play in athletes with coexisting symptomatic intra-articular and extra-articular symptomatology is incumbent upon the treatment of both pathologies.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Correlation of hip capsule morphology with patient symptoms from femoroacetabular impingement

The relationship between morphological characteristics of the hip capsule and patient symptoms in the setting of femoroacetabular impingement (FAI) is undefined. In this study, patients with symptomatic FAI prospectively underwent 3T magnetic resonance (MR) imaging of the affected hip and completed the hip disability and osteoarthritis outcome score (HOOS) to determine the correlation between hip capsule anatomy and patient symptoms. Anterior hip capsule volume, posterior capsule volume, anterior-posterior capsule volume ratio, and proximal-distal volume ratio in the anterior capsule were quantified and measured using axial-oblique intermediate-weighted 3D fast spin echo MR images. A total of 35 patients (35 hips) were included for analysis (mean age: 30.6 years; mean body mass index [BMI]: 24.9 kg/m² ; 57% male). The mean alpha angle was 62.2° ± 4.7°, the mean anterior hip capsule volume was 1705.1 ± 450.3 mm³ , the mean posterior hip capsule volume was 1284.8 ± 268.5 mm³ , the mean anterior to posterior capsule volume ratio was 1.1 ± 0.39, and the mean proximal to distal volume ratio of the anterior capsule was 0.65 ± 0.28. There was no correlation between age, gender, or BMI, and any hip capsule characteristics. Worse scores on the HOOS pain scale were correlated with increased anterior to posterior volume ratio (r = -.38; 95% confidence interval: -0.06 to -0.63). In conclusion, hip capsule morphology correlates with patient symptoms in the setting of FAI as increased anterior capsular volume, relative to posterior capsular volume, is associated with greater patient pain.

Evaluation of Cam Deformity on 3-Dimensional Computed Tomography With the Best-Fit Sphere Technique and the Alpha Angle Marking Method

BACKGROUND

Three-dimensional computed tomography (3D-CT) is commonly used for the evaluation of cam deformity; however, it does not display the cam border directly.

PURPOSE

To compare the efficacy of the best-fit sphere (BFS) method and the alpha angle marking (AAM) method in 3D-CT evaluation for the cam border.

STUDY DESIGN

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

METHODS

Twenty-six cases of cam deformity, confirmed during hip arthroscopy, were included in this study. All patients underwent a CT scan before surgery. Using multiplanar reconstruction, we obtained reformatted CT images of oblique axial, oblique coronal, and radial views. The alpha angle and femoral head-neck offset ratio (hnoR) were measured on the reformatted CT images. The cam area on 3D-CT was displayed in 4 different ways: by importing the markers from the reformatted CT images of the oblique axial view (cam-oa), the oblique coronal view (cam-oc), or the radial view (cam-r) using the AAM method, or by using the BFS method (cam-bfs). The sizes and locations of the displayed cams were compared.

RESULTS

All hips in this study had an alpha angle greater than 60° and an hnoR smaller than 0.17. The radial view measured a larger alpha angle and smaller hnoR than the oblique axial and coronal views (P < .05). The areas of cam-oa, cam-oc, cam-r, and cam-bfs were 161.47 ± 27.96, 89.78 ± 19.23, 241.73 ± 34.55, and 329.75 ± 42.73 mm2, respectively, and their medial-to-lateral ranges along the acetabulum (clockface referents) were 12:30 to 03:00, 11:30 to 01:30, 11:30 to 03:00, and 11:00 to 03:30, respectively. Among the 4 displays, cam-bfs had the largest area and medial-to-lateral range (P < .05), and cam-r had the second largest area and range (P < .05). No significant difference in the mean distances from the acetabular rim to the superior border was detected among the 4 displays (P > .05).

CONCLUSION

The cam area displayed by the BFS method on 3D-CT was larger than those evaluated by the AAM method. In the reformatted CT, the sizes and locations of cam deformity differed among the oblique axial, oblique coronal, and radial views, with the radial view showing the greatest area.

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.

Hip joint space width in an asymptomatic population: Computed tomography analysis according to femoroacetabular impingement morphologies

Background

Although the association between femoroacetabular impingement (FAI) syndrome and hip osteoarthritis (OA) is well established, not all hips exhibiting cam or pincer morphologies (i.e. imaging findings of FAI syndrome) are symptomatic or arthritic. It is difficult to detect which subgroup will wear out, or how does the arthritic process start radiographically. Therefore, we measured in a retrospective study based on computed tomography (CT) analysis, the joint space width (JSW) according to a standard protocol and we investigated its variation according to the presence of a cam and/or pincer morphology. We hypothesized that the radiological presence of a cam and/or pincer hip morphologies, even in asymptomatic subjects, would affect JSW.

Methods

Two hundred pelvic CT scans performed for non-orthopedic etiologies in asymptomatic patients were analyzed using a 3D software. After excluding patients with hip OA or previous hip surgery, 194 pelvic CT scans (388 hips) were retained. We measured for each hip the presence of FAI syndrome imaging findings (cam and pincer morphologies) using the classical parameters of coxometry. In addition, we performed a measurement of articular joint space width according to a standard protocol. We then calculated the mean thickness of 3 defined regions along the femoroacetabular joint: anterior-superior, posterior-inferior, and posterior-superior. Lastly, we compared the JSW across 4 groups: hips with (1) no cam or pincer, (2) pincer, (3) cam, and (4) cam and pincer morphologies using a multivariate analysis. Additionally, a topographic heatmap of JSW was plotted allowing quantitative representation of JSW along the joint.

Results

Increased JSW with peak difference of 0.9 mm (25.7%) was found in hips with cam and pincer morphologies when compared to normal ones (p = 0.002) and to hips with pincer or cam morphologies only.

Conclusion

Positive variations in JSW were associated to the presence of cam and pincer morphologies. This significant increase in JSW could be one of the earliest measurable changes preceding later classical alterations.

The Prevalence of Cam Morphology: A Cross-Sectional Evaluation of 3,558 Cadaveric Femora

Purpose: We sought to determine (1) the prevalence of cam deformity in the population and that of bilateral cam deformity, (2) the typical location of a cam lesion, and (3) the typical size of a cam lesion by direct visualization in cadaveric femora. Methods: Two observers inspected 3,558 human cadaveric femora from the Hamann-Todd Osteological Collection from the Cleveland Museum of Natural History. Any asphericity >2 mm from the anterior femoral neck line was classified as a cam lesion. Once lesions had been inspected, the prevalence in the population, prevalence by gender, and prevalence of bilateral deformity were determined. Additionally, each lesion was measured and localized to a specific quadrant on the femoral neck based upon location of maximal deformity. Results: Cam lesions were noted in 33% of males and 20% of females. Eighty percent of patients with a cam lesion had bilateral lesions. When stratified by location of maximal deformity, 90.9% of lesions were in the anterosuperior quadrant and 9.1% were in the anteroinferior quadrants. The average lesion measured 17 mm long × 24 mm wide × 6 mm thick in men and 14 mm × 22 mm × 4 mm in women (p < 0.05). Conclusions: The population prevalence of cam deformity determined by direct visualization in cadavers may be higher than has been suggested in studies utilizing imaging modalities. Level of Evidence : Level II, diagnostic study.

Cam Osteochondroplasty for Femoroacetabular Impingement Increases Microinstability in Deep Flexion: A Cadaveric Study

PURPOSE

The purpose of this in vitro cadaveric study was to examine the contributions of each surgical stage during cam femoroacetabular impingement (FAI) surgery (i.e., intact-cam hip, T-capsulotomy, cam resection, and capsular repair) toward hip range of motion, translation, and microinstability.

METHODS

Twelve cadaveric cam hips were denuded to the capsule and mounted onto a robotic tester. The hips were positioned in several flexion positions-full extension, neutral (0°), 30° of flexion, and 90° of flexion-and performed internal-external rotations to 5 Nm of torque in each position. The hips underwent a series of surgical stages (T-capsulotomy, cam resection, and capsular repair) and were retested after each stage. Changes in range of motion, translation, and microinstability (overall translation normalized by femoral head radius) were measured after each stage.

RESULTS

Regarding range of motion, cam resection increased internal rotation at 90° of flexion (change in internal rotation = +6°, P = .001) but did not affect external rotation. Capsular repair restrained external rotation compared with the cam resection stage (change in external rotation = -8° to -4°, P ≤ .04). In terms of translation, the hip translated after cam resection at 90° of flexion in the medial-lateral plane (change in translation = +1.9 mm, P = .04) relative to the intact and capsulotomy stages. Regarding microinstability, capsulotomy increased microinstability in 30° of flexion (change in microinstability [Δ_M] = +0.05, P = .003), but microinstability did not further increase after cam resection. At 90° of flexion, microinstability did not increase after capsulotomy (Δ_M = +0.03, P = .2) but substantially increased after cam resection (Δ_M = +0.08, P = .03), accounting for a 31% change with respect to the intact stage.

CONCLUSIONS

Cam resection increased microinstability by 31% during deep hip flexion relative to the intact hip. This finding suggests that iatrogenic microinstability may be due to separation of the labral seal and resected contour of the femoral head.

CLINICAL RELEVANCE

Our in vitro study showed that, at time zero and prior to postoperative recovery, excessive motion after cam resection could disrupt the labral seal. Complete cam resection should be performed cautiously to avoid disruption of the labral seal and postoperative microinstability.

Ultrasound and Ultrasound-Guided Hip Injection Have High Accuracy in the Diagnosis of Femoroacetabular Impingement With Atypical Symptoms

PURPOSE

To evaluate the diagnostic value of ultrasound and ultrasound-guided hip injection in the diagnosis of femoroacetabular impingement (FAI) with atypical symptoms.

METHODS

We evaluated consecutive patients diagnosed with FAI and with atypical symptoms who underwent ultrasound-guided hip injection between January 2017 and February 2019. All patients underwent systematic physical examination, ultrasound examination, magnetic resonance imaging (MRI) examination, and ultrasound-guided injection before surgery. Patients with positive response to ultrasound-guided hip injection were recommended to undergo arthroscopic surgery to treat intra-articular pathology. Sensitivity, specificity, accuracy, and positive predictive value (PPV) of ultrasound and MRI were calculated by using arthroscopic surgery as the gold standard. The accuracy of ultrasound-guided hip injection was recorded. Preoperative and postoperative patient-reported outcomes included visual analog scale for pain and modified Harris Hip Score.

RESULTS

A total of 78 patients with atypical symptoms were diagnosed with FAI. Among these 78 patients, 50 patients had positive responses to injection and 28 patients had negative responses to injection. A total of 36 patients finally underwent arthroscopic surgery. Response to the ultrasound-guided intra-articular injection was 91.7% accurate for detecting the presence of intra-articular abnormality. There were no complications of injection in any of the patients. The sensitivity, PPV, and accuracy by ultrasound diagnosis of cam impingement were 82.9%, 96.7%, and 80.6%, respectively. The sensitivity and accuracy by ultrasound diagnosis of anterosuperior labral tear were both 72.2%. For MRI diagnosis of cam impingement, the sensitivity, PPV and accuracy were 72.2%, 96.3%, and 74.3%, respectively. For MRI diagnosis of labral tear, the sensitivity and accuracy were both 88.9%. Thirty-four patients (94.4%) surpassed the minimal clinically important difference, and 33 patients (91.7%) achieved the patient acceptable symptomatic state.

CONCLUSIONS

Ultrasound and ultrasound-guided hip injection have high accuracy in the diagnosis of femoroacetabular impingement with atypical symptoms.

LEVEL OF EVIDENCE

IV, case series.

Incidence of Femoroacetabular Impingement and Surgical Management Trends Over Time

BACKGROUND

Femoroacetabular impingement (FAI) is a well-known cause of hip pain in adolescents and young adults. However, the incidence in the general population has not been clearly defined.

PURPOSE

To (1) define the population-based incidence of diagnosis of FAI in patients with hip pain, (2) report the trends in diagnosis of FAI over time, and (3) determine the changes in the rate and type of surgical management over time.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A geographic database was used to identify patients who were 14 to 50 years old with hip pain between the years 2000 and 2016. Chart and radiographic review was performed to determine which patients had FAI. To be included, patients had to have a triad of clinical symptoms, physical examination signs, and imaging findings consistent with FAI. Medical records were reviewed to obtain demographic information, clinical history, physical examination findings, imaging details, and treatment details. Statistical analysis determined the overall age- and sex-adjusted annual incidence of FAI diagnosis and trends over time.

RESULTS

There were 1893 patients evaluated with hip pain, and 716 (38%; 813 hips) had diagnosed FAI. The mean ± SD age was 27.2 ± 8.4 years, and 67% were female. The incidence of FAI diagnosis was 54.4 per 100,000 person-years. Female patients had a higher incidence than male patients (73.2 vs 36.1 per 100,000 person-years; P < .01). Incidence of FAI diagnosis were higher from 2010 to 2016 (72.6 per 100,000 person-years; P < .01) as compared with 2005 to 2009 (45.3) and 2000 to 2004 (40.3). Hip arthroscopy, surgical hip dislocation, and periacetabular osteotomy utilization increased from the 2000-2004 to 2010-2016 periods, respectively: 1 (1%) to 160 (20%; P = .04), 2 (1%) to 37 (5%; P = .01), and 1 (1%) to 22 (3%; P = .58).

CONCLUSION

The overall incidence of FAI diagnosis was 54.4 per 100,000 person-years, and it consistently increased between 2000 and 2016. Female patients had a higher incidence than male patients. The utilization of joint preservation operations, including hip arthroscopy, surgical hip dislocation, and anteverting periacetabular osteotomy, increased over time.

Clinical and radiological hip parameters do not precede, but develop simultaneously with cam morphology: a 5-year follow-up study

PURPOSE

The aim of this study was to (1) investigate whether radiographic and clinical parameters, which influence how stresses during sporting activities act on the proximal femur, are associated with cam morphology or (2) precede cam morphology development.

METHODS

Young male football players participated at baseline (n = 89, 12-19 years of age), 2.5-year (n = 63) and 5-year follow-up (n = 49). Standardized anteroposterior pelvic and frog-leg lateral radiographs were obtained at each time-point. Cam morphology was quantified by an alpha angle ≥ 60°, and large cam morphology ≥ 78°. The neck-shaft angle (NSA), epiphyseal extension (EE), lateral center-edge angle (LCEA) and hip internal rotation (IR) were also measured. Cross-sectional associations between NSA, EE, LCEA and IR and (large) cam morphology were studied at all time-points. To study whether these variables preceded cam morphology development, hips without cam morphology at baseline were studied prospectively.

RESULTS

A lower NSA, a higher EE and limited IR were consistently associated with cam morphology at all three time-points. These differences were more pronounced in hips with large cam morphology. No association between cam morphology and the LCEA was found. None of the parameters studied preceded cam morphology development.

CONCLUSION

Cam morphology developed simultaneously with a varus orientation, growth plate extension towards the femoral neck and limited hip internal rotation. These parameters did not precede cam morphology development. The hip parameters studied cannot be used to identify individuals at risk of developing cam morphology.

LEVEL OF EVIDENCE

Level II.

Tonnis Angle and Acetabular Retroversion Measurements in Asymptomatic Hips Are Predictive of Future Hip Pain: A Retrospective, Prognostic Clinical Study

Background:

This study evaluated the prevalence of radiographic abnormalities potentially indicative of femoroacetabular impingement on AP pelvic radiographs in asymptomatic adolescents and young adults and aimed to determine whether the abnormalities were predictive of future hip pain.

Methods:

AP pelvis images from scoliosis radiographs were obtained from patients 12 to 25 years of age free of any clinical hip/lower extremity symptoms between January 2006 and September 2009. The following radiographic abnormalities were collected: lateral center-edge angle of Wiberg >40° or <25°, Tönnis angle <0° or >10°, acetabular retroversion (crossover sign with a posterior wall sign), acetabular overcoverage (crossover sign without a posterior wall sign), and anterior offset alpha angle, calculated using alpha angle of Nötzli >50°. Patients were retrospectively followed (average 3.11 years) to identify those who subsequently developed hip pain.

Results:

Of the 233 patients (466 hips) who were asymptomatic at the time of radiographic evaluation, at least one radiographic abnormality was present in 60% (281/466) of the hips. Within that group of hips (n = 281), 69% (195/281) of hips demonstrated a single abnormality, whereas 31% (86/281) of hips were associated with multiple abnormalities. Among all hips (n = 466), a lateral center-edge angle <25° or >40° was the most common radiographic abnormality, present in 27% (127/466) of hips. Anterior offset alpha angle and acetabular overcoverage were the most common abnormalities to present together, found in 5% (25/466) of hips. In the multivariable model, a decreasing Tönnis angle (hazard ratio per 1-degree decrease: 1.25, 95% confidence interval, 1.10–1.42, P = 0.0006) and the presence of acetabular retroversion (hazard ratio: 3.55, 95% confidence interval, 1.15–10.95, P = 0.0272) were predictive of the development of future hip pain.

Conclusions:

Our study demonstrates a high prevalence of radiographic abnormalities indicative of femoroacetabular impingement in asymptomatic adolescents and young adults. A decrease in Tönnis angle and the presence of acetabular retroversion were predictive of future hip pain.

The efficacy of intra-articular HYADD4-G injection in the treatment of femoroacetabular impingement: results at one year follow up

Objective

Femoroacetabular impingement (FAI) is a condition that has been increasingly recognized as a source of hip pain and a possible risk factor to early development of hip osteoarthritis (OA). To our knowledge, the use of HA in the treatment of femoroacetabular FAI has been investigated only by two studies, both using a high molecular weight HA. The aim of this study was to evaluate the efficacy of two weekly injections of an hexadecylamide derivative of HA (HYADD4-G, HYMOVIS, Fidia Farmaceutici) in FAI.

Methods

All patients received two weekly intra-articular injections of Hymovis at baseline and after 7 days. Clinical and functional assessments were performed at baseline and was repeated after 1, 3, 6 and 12 months. Functional measures included visual analogue scale (VAS) for pain, Harris Hip score (HHS), Lequesne Index (LI), Tegner activity level scale (TALS) and monthly consumption of nonsteroidal anti-inflammatory drugs (NSAIDs).

Results

Twenty-one hips (19 patients, 2 bilateral cases) were treated. The variables VAS, HHS as well as Lequesne improved significantly from T0 to T4 (at 12 months) with the best improvement between T0 and T1. At the same time, a reduction in NSAIDs monthly intake was registered. On the other hand, a significant improvement in Tegner scale was not observed. No adverse events were registered.

Conclusion

This study states that one cycle of HYADD4-G could be a safe and effective treatment in patients with FAI, showing significative results in term of pain control as well as hip functionality and quality of life up to 1 year.

Characteristics of Soccer Players Undergoing Primary Hip Arthroscopy for Femoroacetabular Impingement: A Sex- and Competitive Level-Specific Analysis

BACKGROUND

Radiographic features of femoroacetabular impingement (FAI) are prevalent in kicking athletes, especially soccer players. However, there remains a paucity of data on the characteristics of symptomatic soccer players with an established diagnosis of FAI.

PURPOSE

To report on patient demographics, injury, and clinical and radiographic characteristics in a large cohort of soccer players who underwent primary hip arthroscopy for FAI and to perform a sex- and competition level-specific analysis of these data.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

An institutional hip preservation registry containing 3318 consecutive primary hip arthroscopies for FAI performed between March 2010 and January 2016 was retrospectively reviewed for patients identified as soccer players. Patient demographics, injury characteristics, and clinical and radiographic findings were recorded, and sex- and competition level-specific differences were analyzed.

RESULTS

A total of 421 hips (336 soccer players) were identified, including 257 (61.0%) men and 164 (39.0%) women. Of these, 105 (24.9%) were reported as highly competitive, 194 (46.1%) as competitive, 75 (17.8%) as recreational, and 47 (11.2%) did not report a level. The majority of the 336 soccer players (231 hips; 55%) reported chronic hip pain lasting >6 months with no acute injury at the initial visit. Alpha angle, coronal center-edge angle, and femoral version on computed tomography scan measured 64.5°± 12°, 32.3°± 9°, and 13.7°± 10° (mean ± SD), respectively. There were 230 (55%) hips with a type 2 anterior inferior iliac spine (AIIS), 78 (18.5%) with a type 1 AIIS, and 19 (4.5%) with a type 3 AIIS. When compared with male athletes, female athletes had more hip internal rotation on physical examination (14.9° vs 8°; P < .001), lower alpha angles (57.5° vs 68.5°; P < .001), and lower-grade AIIS morphology (P = .003). Acute injury as the reason for hip symptoms was most likely in the highly competitive group (P < .001).

CONCLUSION

Female soccer players were more likely to have less severe clinical and radiographic findings than were male soccer players. Acute injury as the cause of hip symptoms was more common in highly competitive players.

CLINICAL RELEVANCE

Focusing on soccer players with an established FAI diagnosis, the findings of this study suggest that there are sex- and competition level-based differences in the presentation, physical examination, and imaging characteristics among the players. These findings can better guide clinicians in the diagnostic evaluation of symptomatic soccer players with FAI and in tailoring treatment recommendations to specific cohorts.

Patient-specific factors are associated with severity of chondrolabral injury in patients with femoroacetabular impingement

PURPOSE

The purpose of this study was to evaluate the relationship between patient-specific factors, preoperative radiographic findings, and the presence and severity of chondrolabral damage identified during hip arthroscopy for femoroacetabular impingement.

METHODS

Between 2014 and 2017, patients who underwent hip arthroscopy for FAI and labral tear were retrospectively reviewed. Patient-specific variables including age, gender, BMI, LCEA, and alpha angle were collected. Surgical reports were reviewed for labral tear position and size, as well as severity of acetabular and femoral chondromalacia.

RESULTS

There were 205 patients who met inclusion criteria with a mean age of 33 years (range 15-66), BMI 26.5 (range 15.9-44.5), LCEA 32.2° (range 21.0°-56.0°) and alpha angle 59.1° (range 33.0°-86.0°). Greater age (p = 0.023), alpha angle (p = 0.011) and male gender (p < 0.001) significantly correlated with high-grade acetabular chondral damage. Increased LCEA (p < 0.001), increased alpha angle (p = 0.012), and greater age (p = 0.002) were significantly associated with increased labral tear size.

CONCLUSIONS

Greater age, male gender, increased BMI and increased alpha angle were associated with more advanced acetabular chondromalacia. Additionally, greater age, increased LCEA, and increased alpha angle was associated with larger labral tear size.

LEVEL OF EVIDENCE

IV.

Primary and Revision Circumferential Labral Reconstruction for Femoroacetabular Impingement in Athletes: Return to Sport and Technique

PURPOSE

To determine return-to-play rates and hip-specific outcomes in athlete hips with femoroacetabular impingement syndrome treated with circumferential labral reconstruction (CLR).

METHODS

All consecutive patients who underwent CLR from January through December 2016 performed by the senior surgeon with complete 2-year outcome scores were identified. The hips of 57 non-athletes who underwent CLR were excluded from analysis, as were 165 patients who underwent labral repair and 4 patients who underwent labral debridement. Outcome measures were completed by patients within 1 week prior to surgery and between 22 and 26 months postoperatively. Thirty patients met the inclusion criteria for this study. All 30 participated in regular, competitive athletic events and had magnetic resonance arthrogram-confirmed labral tears, and nonsurgical measures had failed. Of the 30 patients, 5 (16.7%) participated in cutting sports; 5 (16.7%), asymmetrical or overhead sports; 4 (13.3%), contact sports; 13 (43.3%), endurance sports; and 3 (10.0%), flexibility sports. Moreover, 25 of 30 (83.3%) were high-level athletes. Both primary (n = 23) and revision (n = 7) procedures were included.

RESULTS

As determined by the International Hip Outcome Tool 12 score, 28 of 30 patients (93.3%) met the patient acceptable symptomatic state whereas 30 of 30 (100%) achieved substantial clinical benefit and exceeded the minimal clinically important difference for their operative hip. In addition, 23 of 30 patients (76.6%) met the patient acceptable symptomatic state whereas 30 of 30 (100%) achieved substantial clinical benefit and exceeded the minimal clinically important difference for the operative hip as determined by the visual analog scale pain score. Of 30 patients, 26 (86.7%) were able to return to play. The mean time to return to play was 6.6 months (standard deviation, 2.4 months).

CONCLUSIONS

Two-year outcomes in this population of athletes undergoing CLR for femoroacetabular impingement syndrome show a statistically and clinically significant improvement in patient-reported outcomes, a statistically and clinically significant decrease in pain, and an overall return-to-play rate of 86.7%.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Return to Sports After Joint Preservation Hip Surgery

Femoroacetabular impingement results from a mismatch of congruency between the femoral head and the acetabulum. This condition is most common among young, active patients and may lead to pain, decreased quality of life, and inability to participate in athletics. Hip preservation surgery is widely performed is used as a definitive treatment option in athletes at all levels of competition. Athletes have reported high rates of return to play and satisfaction and expect rehabilitation to require approximately 4 to 6 months. This article provides an overview of femoroacetabular impingement, including diagnosis and treatment, with focus on athletes and return to play.

Population-based prevalence of femoroacetabular impingement in Japan

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

BACKGROUND

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

PURPOSE

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSION

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

The Hip Suction Seal, Part II: The Effect of Rim Trimming, Chondrolabral Junction Separation, and Labral Repair/Refixation on Hip Distractive Stability

BACKGROUND

The acetabular labrum contains free nerve endings, and an unstable labrum can result in increased femoral head movement during hip motion. This can be caused by chondrolabral junction (CLJ) separation, especially in association with pincer-type femoroacetabular impingement, and may contribute to hip pain.

HYPOTHESIS

Rim resection alone has no effect on suction seal biomechanics. Further, separation of the CLJ changes hip suction seal biomechanics when compared with those of the native state, whereas repair and refixation with suture anchors restore these biomechanical parameters.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 12 fresh-frozen human cadaveric hips were used in this study. Hips were mounted in a saline bath on a dynamic tensile testing machine and were distracted at a rate of 0.5 mm/s from neutral position. A total of 3 parameters (force, displacement, and intra-articular pressure) were measured throughout testing. Before testing, hips were randomly allocated to 1 of 2 groups: 1 that included the CLJ separation (CLJ Cut group) and 1 that did not (CLJ Intact group). Hips were tested in the following states: (1) native, (2) rim trimming, (3) separated CLJ (CLJ Cut group only), and (4) labral repair/refixation. For each group a linear mixed-effects model was used to compare biomechanical parameters between states.

RESULTS

Rim trimming did not affect any suction seal parameters relative to those of the native state. In the CLJ Cut group, no significant difference in distance to break the suction seal was observed for any states compared with that of the native state. In the CLJ Intact group, the distance to break the suction seal was significantly shorter in the labral refixation state (1.8 mm) than the native state (5.6 mm; P = .002). The maximum distraction force (62.1 ± 54.1 N) and the peak negative pressure (-36.6 ± 24.2 kPa) of the labral repair/refixation state were significantly lower than those of the native state in both groups (93.4 ± 41.7 N, P = .01; -60.7 ± 20.4 kPa, P = .02).

CONCLUSION

Rim trimming did not change the biomechanical properties of the labral suction seal. Labral refixation resulted in a shorter distance to break the labral suction seal. This indicates that labral mobility is reduced by the labral refixation procedure, which could be beneficial in postoperative pain relief and labral healing.

CLINICAL RELEVANCE

The labral refixation reduced labral mobility, which could be beneficial for both pain relief and labral healing to the acetabulum after pincer-type femoroacetabular impingement resection.

Classifying Cam Morphology by the Alpha Angle: A Systematic Review on Threshold Values

Background

The alpha angle is the most often used measure to classify cam morphology. There is currently no agreement on which alpha angle threshold value to use.

Purpose

To systematically investigate the different alpha angle threshold values used for defining cam morphology in studies aiming to identify this threshold and to determine whether data are consistent enough to suggest an alpha angle threshold to classify cam morphology.

Study Design

Systematic review; Level of evidence, 3.

Methods

The Embase, Medline (Ovid), Web of Science, Cochrane Central, and Google Scholar databases were searched from database inception to February 28, 2019. Studies aiming at identifying an alpha angle threshold to classify cam morphology were eligible for inclusion.

Results

We included 4 case-control studies, 10 cohort studies, and 1 finite-element study from 2437 identified publications. Studies (n = 3) using receiver operating characteristic (ROC) curve analysis to distinguish asymptomatic people from patients with femoroacetabular impingement syndrome consistently observed alpha angle thresholds between 57° and 60°. A 60° threshold was also found to best discriminate between hips with and without cam morphology in a large cohort study based on a bimodal distribution of the alpha angle. Studies (n = 8) using the upper limit of the 95% reference interval as threshold proposed a wide overall threshold range between 58° and 93°. When stratified by sex, thresholds between 63° and 93° in male patients and between 58° and 94° in female patients were reported.

Conclusion

Based on the available evidence, mostly based on studies using ROC curve analysis, an alpha angle threshold of ≥60° is currently the most appropriate to classify cam morphology. Further research is required to fully validate this threshold.

Cross-cultural adaptation, and validation of the Turkish version of the Nonarthritic Hip Score

OBJECTIVE

The aim of this study was to translate and cross-culturally adapt the Nonarthritic Hip Score (NAHS) into Turkish and determine the validity and reliability of the translated version in physically active patients with hip pain.

METHODS

Sixty young to middle-aged and physically active patients (34 women and 26 men; mean age=35 years; age range: 18-40 years) with hip pain were included in the study. The original version of the NAHS was first translated into Turkish and back-translated into English by two bilingual translators each. The back-translated version was compared with the initial English version by a committee of the four translators. The Turkish version was then tested with 15 patients with hip pain and 15 healthy individuals. The participants were asked whether they had difficulties in understanding the questions. Subsequently, the questionnaire was accepted for use in the study population. Test-retest reliability and internal consistency were assessed using Intraclass Correlation Coefficient (ICC) and Cronbach's alpha, respectively. The construct validity was determined via the Pearson correlation coefficient between the NAHS and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), modified Harris Hip Score (mHHS), and Short Form-12 (SF-12). Floor and ceiling effects were analyzed. Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were performed to test construct validity.

RESULTS

An ICC of 0.994 and Cronbach's alpha value of 0.908 were obtained; thus, the Turkish version of the NAHS was reliable. Neither floor nor ceiling effects (15%) were found in the sub-parameters (8.3-1.7%) and the total score (1.7%) of the NAHS. The EFA test showed that this questionnaire had four factors. Model fit indices in CFA were χ2/df=2.23, Tucker-Lewis index=0.90, comparative fit index=0.91, goodness of fit index=0.63, root mean square error of approximation=0.14 (90% CI: 0.12-0.16). The NAHS total score showed an excellent correlation with WOMAC (r=-0.909), mHHS (r=0.850), and SF-12 (r=0.811) scores.

CONCLUSION

The Turkish version of the NAHS is a valid and reliable questionnaire for young and physically active patients with hip pain.

LEVEL OF EVIDENCE

Level II, Diagnostic study.

The prevalence of femoroacetabular impingement anatomy in Division 1 aquatic athletes who tread water

Femoroacetabular impingement (FAI) is a disorder that causes hip pain and disability in young patients, particularly athletes. Increased stress on the hip during development has been associated with increased risk of cam morphology. The specific forces involved are unclear, but may be due to continued rotational motion, like the eggbeater kick. The goal of this prospective cohort study was to use magnetic resonance imaging (MRI) to identify the prevalence of FAI anatomy in athletes who tread water and compare it to the literature on other sports. With university IRB approval, 20 Division 1 water polo players and synchronized swimmers (15 female, 5 male), ages 18-23 years (mean age 20.7 ± 1.4), completed the 33-item International Hip Outcome Tool and underwent non-contrast MRI scans of both hips using a 3 Tesla scanner. Recruitment was based on sport, with both symptomatic and asymptomatic individuals included. Cam and pincer morphology were identified. The Wilcoxon Signed-Rank/Rank Sum tests were used to assess outcomes. Seventy per cent (14/20) of subjects reported pain in their hips yet only 15% (3/20) sought clinical evaluation. Cam morphology was present in 67.5% (27/40) of hips, while 22.5% (9/40) demonstrated pincer morphology. The prevalence of cam morphology in water polo players and synchronized swimmers is greater than that reported for the general population and at a similar level as some other sports. From a clinical perspective, acknowledgment of the high prevalence of cam morphology in water polo players and synchronized swimmers should be considered when these athletes present with hip pain.

Predicting Incident Radiographic Knee Osteoarthritis in Middle-Aged Women Within Four Years: The Importance of Knee-Level Prognostic Factors

OBJECTIVE

To develop and internally validate risk models and a clinical risk score tool to predict incident radiographic knee osteoarthritis (RKOA) in middle-aged women.

METHODS

We analyzed 649 women in the Chingford 1,000 Women study. The outcome was incident RKOA, defined as Kellgren/Lawrence grade 0-1 at baseline and ≥2 at year 5. We estimated predictors' effects on the outcome using logistic regression models. Two models were generated. The clinical model considered patient characteristics, medication, biomarkers, and knee symptoms. The radiographic model considered the same factors, plus radiographic factors (e.g., angle between the acetabular roof and the ilium's vertical cortex [hip α-angle]). The models were internally validated. Model performance was assessed using calibration and discrimination (area under the receiver characteristic curve [AUC]).

RESULTS

The clinical model contained age, quadriceps circumference, and a cartilage degradation marker (C-terminal telopeptide of type II collagen) as predictors (AUC = 0.692). The radiographic model contained older age, greater quadriceps circumference, knee pain, knee baseline Kellgren/Lawrence grade 1 (versus 0), greater hip α-angle, greater spinal bone mineral density, and contralateral RKOA at baseline as predictors (AUC = 0.797). Calibration tests showed good agreement between the observed and predicted incident RKOA. A clinical risk score tool was developed from the clinical model.

CONCLUSION

Two models predicting incident RKOA within 4 years were developed, including radiographic variables that improved model performance. First-time predictor hip α-angle and contralateral RKOA suggest OA origins beyond the knee. The clinical tool has the potential to help physicians identify patients at risk of RKOA in routine practice, but the tool should be externally validated.

Pelvic incidence in a femoroacetabular impingement population

Objective

We aim to determine if pelvic incidence (PI) differed between a symptomatic femoroacetabular impingement (FAI) population and a control.

Methods

We retrospectively identified a cohort of symptomatic FAI patients and compared measured PI to a control group.

Results

The PI was significantly lower in the FAI group compared to the control (51.32±1.07 vs. 55.63±1.04; P < 0.01).

Conclusion

The mean PI was significantly decreased in the FAI population compared to a control.

Protocol for a multicenter prospective cohort study evaluating sport activity and development of femoroacetabular impingement in the adolescent hip

BACKGROUND

Femoroacetabular impingement (FAI) is an important cause of hip pain in young and active individuals and occurs as a result of size and shape mismatch between the femoral head and acetabulum. Open physes in children can make hips more susceptible to injury, and high impact forces have been suggested to affect the developing femur. The diagnosis of FAI has recently risen, especially within adolescent populations, and there is an increasing trend towards year-round participation in sports with early specialization. The PREVIEW study is an international longitudinal study designed to determine the association between sport specialization in adolescence and the development of hip impingement.

METHODS

This is a multicentre prospective cohort study evaluating 200 participants between the ages of 12-14 that include sport specialists at the moderate to vigorous physical activity (MVPA) level and non-sport specialists at any activity level. We will monitor physical activity levels of all participants using an activity log and a wrist-mounted activity tracker, with synced data collected every 3 months during the study period. In addition, participants will be evaluated clinically at 6, 12, and 18 months and radiographically at the time of enrolment and 24 months. The primary outcome is the incidence of FAI between groups at 2 years, determined via MRI. Secondary outcomes include hip function and health-related quality of life between subjects diagnosed with FAI versus no FAI at 2 years, as determined by the Hip Outcome Score (HOS) and Pediatric Quality of Life (PedsQL) questionnaires.

DISCUSSION

It is important to mitigate the risk of developing hip deformities at a young age. Our proposed prospective evaluation of the impact of sport activity and hip development is relevant in this era of early sport specialization in youth. Improving the understanding between sport specialization and the development of pre-arthritic hip disease such as FAI can lead to the development of training protocols that protect the millions of adolescents involved in sports annually.

TRIAL REGISTRATION

PREVIEW is registered with clinicaltrials.gov (NCT03891563).

Bilateral versus unilateral hip arthroscopy for femoroacetabular impingement: a systematic review

One in four patients presenting with femoroacetabular impingement (FAI) has bilateral symptoms, and despite excellent outcomes reported after arthroscopic treatment of FAI, there remains a paucity of data on the outcomes following bilateral hip arthroscopy. This systematic review aims to examine the outcomes following bilateral (either ‘simultaneous’ or ‘staged’) versus unilateral hip arthroscopy for FAI. A systematic review of multiple electronic databases was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and checklist. All studies comparing simultaneous, staged and/or unilateral hip arthroscopy for FAI were eligible for inclusion. Case series, case reports and reviews were excluded. All study, patient and hip-specific data were extracted and analyzed. The Newcastle–Ottawa Scale was used to assess study quality. A meta-analysis was not performed due to heterogeneity among outcome measures. A total of six studies, including 722 patients (42.8% male) and 933 hips were eligible for inclusion. The mean age across patients was 35.5. The average time between staged procedures was 7.7 months. Four of the six studies were retrospective cohort studies, while the remaining two were prospective in nature. The overall quality of the eligible studies was found to be good. No significant difference was noted among patient-reported outcomes (modified Harris hip score, hip outcome score and non-arthritic hip score), visual analog scale, return to sport, traction time and complications between those undergoing bilateral (simultaneous or staged) versus unilateral hip arthroscopy. Based on the current available evidence, bilateral hip arthroscopy (whether simultaneous or staged) exhibits similar efficacy and safety when compared with unilateral hip arthroscopy. However, further prospective study is required to confirm this finding.

Labral tears with axial plane disorders

OBJECTIVES

This study aims to determine if there is an axial plane coverage insufficiency in patients with symptomatic labral tears compared to the contralateral asymptomatic side and healthy control subjects.

PATIENTS AND METHODS

This retrospective study was conducted between December 2017 and January 2019. Thirty patients (21 males, 9 females; mean age 28 years; range, 20 to 36 years) operated due to unilateral symptomatic acetabular labral tears secondary to femoroacetabular impingement were evaluated. Twenty asymptomatic patients (13 males, 7 females; mean age 27±9 years; range, 19 to 36 years) were included in the control group. The relationship between acetabular morphology and labral tear was investigated with the comparison of unilateral symptomatic hips with contralateral asymptomatic hips and the control group by using radiological parameters on plain radiographs and computed tomography.

RESULTS

When the patient group symptomatic side was compared to the control group, acetabular anteversion angle (A A A) and alpha (α) angle were higher, while posterior acetabular sector angle and horizontal acetabular sector angle were lower. When the asymptomatic side was compared to the control group, AAA was higher in the patient group. There was no difference between the symptomatic and asymptomatic sides in the patient group; the symptomatic side yielded a higher α; angle.

CONCLUSION

Posterior axial plane coverage deficiency in combination with cam deformity (increased α angle) seems to play a role in the pathogenesis of symptomatic acetabular labral tears, even creating a side-to-side difference in some individuals.

Acetabular posterior wall morphology. A CT-based method to distinguish two acetabular posterior wall types

Background

The anatomy of the posterior wall of the acetabulum is important for the hip stability. We wanted to know whether differences can be observed.

Material and methods

On lateral 3D pelvic CT reconstruction of the pelvis two types were identified. On axial CT-images acetabular angles were determined.

Results

We observed 35 type I acetabular and 61 type II acetabular. Posterior acetabular sector angle was 114° in type I and 94° in type II acetabular (p < 0.01). At an cut-off angle of 100° we could predict the type of acetabulum.

Conclusions

We could describe reference values for the posterior wall to distinguish two morphological types.

Corrections in alpha angle following two different operative approaches for CAM-type femoral acetabular impingement - Ganz surgical hip dislocation vs anterior mini-open

BACKGROUND

Femoroacetabular impingement (FAI) is a predisposing factor for secondary osteoarthritis of the hip joint. The two extensively described impingement mechanisms of FAI are CAM and Pincer-type. Initially managed conservatively, operative intervention should be offered to the persistently symptomatic patient. The measurement of the alpha angle is considered a standard method of assessing the severity of pathology in Cam-type FAI on pre-operative plain radiographs. The radiological correction of the alpha angle has not been previously compared between different surgical approaches. We hypothesize that there is no difference in alpha angle correction between Ganz surgical hip dislocation and the anterior mini-open approach.

AIM

To compare the magnitude of alpha angle correction achieved by using the Ganz surgical hip dislocation and the anterior mini-open approach.

METHODS

This is a retrospective study assessing seventy-nine patients identified in a 5-year period. These patients had preoperative radiographic evidence of FAI and underwent surgery by a single surgeon at our institution, a tertiary care center. Patients with missing radiographic documentation, radiographs with insufficient quality which then precluded accurate measurement of the angle α, a diagnosed congenital condition, isolated type II pathology (Pincer), and history of prior surgery were excluded from the study. Either the Ganz surgical hip dislocation or the anterior mini open approach was used. Postoperative radiographic evaluation of the alpha angle between the two surgical methods was done and corrected for age and gender using two-sample t-tests and Chi-square analyses.

RESULTS

A total of 79 patients met the inclusion and exclusion criteria. Forty-seven males (mean age of 35.3, range 16-53) and 32 females (mean age 36.7, range 16-60) were enrolled. Forty-seven patients underwent the anterior mini-open approach, and 32 underwent the Ganz surgical hip dislocation. There were no significant differences in age between the two surgical groups or in pre- and post-operative alpha angles based on patient gender. The mean pre-operative alpha angle for the Ganz surgical hip dislocation group was 88.0 degrees (SD 12.3) and 99.4 degrees (SD 7.2) for the anterior mini-open group. Mean post-operative angles were 49.9 degrees (SD 4.3) for the Ganz surgical hip dislocation and 43.8 (SD 4.3) degrees for the anterior mini-open group. There was a statistically significant difference in patient’s pre-operative and post-operative angles (P = 0.000) with both surgical approaches.

CONCLUSION

Statistically significant decreases in alpha angle were noted for both surgical techniques, with larger decreases seen in the anterior mini-open group.

Young elite Alpine and Mogul skiers have a higher prevalence of cam morphology than non-athletes

PURPOSE

To investigate the prevalence of cam morphology in (1) a group of young elite Mogul and Alpine skiers compared with non-athletes and (2) between the sexes.

METHOD

The hip joints of 87 subjects [n = 61 young elite skiers (29 females and 32 males) and n = 26 non-athletes (17 females and 9 males)] were examined using MRI, for measurements of the presence of cam morphology (α-angle ≥ 55).

RESULTS

The skiers had a significantly higher prevalence of cam morphology compared with the non-athletes (49% vs 19%, p = 0.009). A significant difference (p < 0.001) was also found between females and males, where 22% of the females and 61% of the males had cam morphology. Among the skiers, there was also a significant difference (p < 0.001) between the sexes, where 28% of the females and 68% of the males had cam morphology. This difference between the sexes was not found in the non-athletic group. No significant differences were found between Mogul and Alpine skiers.

CONCLUSION

Young male elite skiers have a higher prevalence of cam morphology of the hips compared with non-athletes.

LEVEL OF EVIDENCE

II.

The borderline dysplastic hip: when and how is it abnormal?

Borderline acetabular dysplasia refers to mildly sub-normal patterns of acetabular shape and coverage that might predispose children to mechanical dysfunction and instability. Borderline dysplasia generally includes children with a lateral center edge angle (CEA) of 18-24°. Some children with borderline radiographic measurements have normal joint mechanics and function while others benefit from acetabular reorienting surgery. Although radiographic findings of borderline dysplasia might suggest instability, the ultimate diagnosis is based on history and physical exam in addition to imaging. Children with borderline acetabular dysplasia sometimes benefit from other cross-sectional imaging studies such as MR imaging to evaluate for secondary evidence of instability, including damage along the acetabular rim, or labral degeneration and hypertrophy. CT is also helpful for depiction of 3-D acetabular morphology for preoperative assessment and planning. Pediatric radiologists are often the first to identify borderline or mild dysplasia on radiographs. It is imperative that pediatric radiologists serve as effective consultants and offer appropriate recommendations as part of a cohesive multidisciplinary approach to this complex patient population.

Age and sex-related distribution of alpha angles and the prevalence of the cam morphology of the hip in Asians do not differ from those of other ethnicities

PURPOSE

This study was performed to evaluate the effects of age on the alpha angle and the incidence of asymptomatic cam morphology.

METHODS

The radiographs of asymptomatic individuals between ages 8 and 22 were retrospectively collected. A total of 1417 individuals were included and grouped according to age: 8-12 (Group A), 13-18 (Group B), and 19-22 (Group C) years. Radiographic measurements of the alpha angles of the right hip were obtained from anteroposterior (AP) and frog-leg lateral (FL) radiographs. The correlations among alpha angles, the presence of cam morphology, and age were determined.

RESULTS

The mean alpha angles of the three groups were statistically different (p < 0.001, each). The alpha angles on both radiographs were positively correlated with age. Intra-group analysis revealed that this correlation was only evident on the FL images of males in Group B. The presence of a radiographic cam morphology also positively correlated with age (p < 0.001 in both AP and FL images). The cam morphology on AP radiographs was 0 in Group A, 17(3.0%) in Group B, and 21(4.8%) in Group C; that on FL radiographs was 2(0.3%) in Group A, 45(7.9%) in Group B, and 103(23.6%) in Group C. Intra-group analysis revealed that the correlation was only significant in males in Group B.

CONCLUSIONS

Higher alpha angles and the presence of cam morphology were positively correlated with age, particularly in males at or before the time of skeletal maturation. The prevalence of cam morphology did not differ from those in other ethnicities.

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.

Treatment of cam-type femoroacetabular impingement using anterolateral mini-open and arthroscopic osteochondroplasty

BACKGROUND

Femoroacetabular impingement (FAI) is associated with decreased hip function and early hip osteoarthritis. Surgical treatment is often required to halt the process of mechanical degeneration. The study investigated the short-to-midterm results of using a modified anterolateral mini-open and arthroscopic osteochondroplasty in the treatment of cam-type FAI.

METHODS

Thirty-six patients (39 hips), with the mean age of 43.6 years, who had cam-type FAI, were operated by a mini-open and arthroscopy-assisted osteochondroplasty via the Watson-Jones interval between 2002 and 2016. Radiographic parameters and Harris hip scores were retrospectively analyzed after a mean follow-up of 44 months.

RESULTS

Of the 39 hips, the mean Harris hip score significantly improved from 61.1 preoperatively to 84.2 postoperatively (P < 0.01). There were nine hips (23%) undergoing total hip arthroplasty (THA) at a mean of 22 months (range, 3~64 months) due to progression of hip osteoarthritis. The 5-year survival for hip preserving was 74.9%. Cox proportional-hazards model showed that age ≥ 55 years (P = 0.03) and preoperative Tönnis stage II (P = 0.02) were independent risk factors for conversion to THA.

CONCLUSIONS

The mini-open and arthroscopic approach allowed direct visualization and improved quality of the osteochondroplasty of FAI hip while avoiding the need for surgical dislocation. This technique could be a safe and viable option for symptomatic cam-type FAI patients to relieve symptoms and improve hip function.

Increased pelvic mobility and altered hip muscles contraction patterns: two-year follow-up cam-FAIS corrective surgery

Femoroacetabular impingement syndrome (FAIS) surgery can produce improvements in function and patient satisfaction; however, data on muscle assessment and kinematics of high mobility tasks of post-operative patients is limited. The purpose of this study was to evaluate kinematics and muscle activity during a deep squat task, as well as muscle strength in a 2-year follow-up FAIS corrective surgery. Eleven cam morphology patients underwent motion and electromyography capture while performing a squat task prior and 2-years after osteochondroplasty and were BMI-, age- and sex-matched to 11 healthy control (CTRL) participants. Isometric muscle strength, flexibility and patient-reported outcome measures (PROMs) were also evaluated. Post-operative FAIS was significantly weaker during hip flexion (23%) and hip flexion-with-abduction (25%) movements when compared with CTRL, no improvements in squat depth were observed. However, post-operative FAIS increased the pelvic range of motion during the squat descent (P = 0.016) and ascent (P = 0.047). They had greater peak activity for the semitendinosus and total muscle activity for the gluteus medius, but decreased peak activity for the glutei and rectus femoris during squat descent; greater total muscle activity for the tensor fascia latae was observed during squat ascent (P = 0.005). Although not improving squat depth, post-operative patients increased pelvic ROM and showed positive PROMs. The muscle weakness associated with hip flexion and flexion-with-abduction observed at the follow-up can be associated with the alterations in the muscle activity and neuromuscular patterns. Rehabilitation programs should focus on increasing pelvis and hip muscles flexibility and strength.

Persons with femoroacetabular impingement syndrome exhibit altered pelvifemoral coordination during weightbearing and non-weightbearing tasks

BACKGROUND

Previous studies have reported that persons with femoroacetabular impingement syndrome (FAIS) have diminished posterior tilt of the pelvis during functional tasks. It is not known how this movement impairment impacts pelvifemoral coordination during weightbearing and non-weightbearing movements.

METHODS

Fifteen persons with a diagnosis of FAIS and 15 matched controls performed a deep squat (weightbearing) and a maximum height stepping task (non-weightbearing). Peak hip flexion, posterior pelvis tilt excursion, and the ratio of sagittal plane pelvis to femur motion during the period of pelvis posterior tilt were calculated for each task. Two factor ANOVAs were used to evaluate differences between groups and tasks.

FINDINGS

With regards to peak hip flexion, there were no significant group differences for either task. When averaged across tasks, the FAIS group exhibited significantly less posterior tilt excursion (12.1° (SD 9.1°) vs 20.6° (SD 9.3°)) and smaller pelvifemoral ratios (0.24 (SD 0.14) vs 0.39 (SD 0.16)) compared to the control group.

INTERPRETATION

Persons with FAIS exhibit altered pelvifemoral coordination regardless of weightbearing status. This finding suggests that decreased hip and/or lumbopelvic mobility may contribute to altered movement patterns at the hip.

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

BACKGROUND

Bilateral symptomatic femoroacetabular impingement (FAI) is common. However, the fate of asymptomatic hip in patients with the radiographic diagnosis of bilateral FAI and unilateral symptoms remains unknown.

QUESTIONS/PURPOSES

(1) What is the likelihood of the asymptomatic hip becoming painful in patients with unilateral symptoms but with radiographic evidence of bilateral femoroacetabular impingement? (2) What radiological and clinical factors are associated with the development of symptoms in an asymptomatic hip diagnosed with FAI?

METHODS

A longitudinally maintained institutional FAI database was queried to collect relevant data for this retrospective study. To answer our research questions, we created a cohort of patients with bilateral radiographic signs of FAI but only unilateral symptoms at the time of initial presentation. Between 2004 and 2016, a senior surgeon (JP) at one institution treated 652 patients for hip pain determined to be from FAI, a diagnosis we made based on clinical symptoms, physical exam, and diagnostic imaging. We excluded 95 patients (15%) because of inadequate data or other diagnoses, which left 557 patients. Of those, 170 patients (31%) had bilateral radiological diagnosis of FAI, and 88 (52%) of them had bilateral hip symptoms, and so were excluded. Of the remaining 82 patients, eight (10%) underwent bilateral FAI surgery under the same anesthetic despite having only unilateral symptoms, leaving 74 for analysis in this study. Patients were followed with annual clinic visits, or contacted by phone and electronically. We defined onset of symptoms using a modified Harris Hip Score (mHHS) or the University of California at Los Angeles (UCLA) activity scale, and used a logistic regression model to identify factors associated with the development of symptoms.

RESULTS

Of the 74 patients with bilateral FAI and an asymptomatic hip at initial presentation, 60 (81%) became symptomatic at a mean 2 years (range, 0.3-11 years) followup. Of these 60 patients, 43 (72%) eventually underwent subsequent surgical intervention. After controlling for potential confounding variables such as sex, age, BMI, history of trauma we identified that reduced neck-shaft angle (r = -0.243, p = 0.009), increased lateral center-edge angle (r = 0.123, p = 0.049), increased alpha angle (r = 0.069, p = 0.025), and younger age (r = -0.071, p = 0.046) were associated with the development of symptoms in the contralateral hip. With the numbers available, none of the other examined variables such as sex, BMI, history of trauma, psychiatric condition, employment, Tönnis grade, Tönnis angle, crossover sign, type of impingement, and joint congruency were found to be associated with symptom progression.

CONCLUSIONS

Bilateral FAI may be observed about one-third of patients. Most patients with unilateral symptomatic FAI and radiographic diagnosis of bilateral FAI in this cohort became symptomatic relatively quickly and most of them underwent subsequent surgical intervention in the contralateral hip. Reduced neck-shaft angle, increased lateral center-edge angle, increased alpha angle, and younger age were associated with symptom development in the contralateral hip. Hip preservation surgeons may use the finding of this study to counsel patients who present with bilateral FAI but only unilateral symptoms about the natural history of their condition.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Cam FAI and Smaller Neck Angles Increase Subchondral Bone Stresses During Squatting: A Finite Element Analysis

BACKGROUND

Individuals with a cam deformity and a decreased (varus) femoral neck-shaft angle may be predisposed to symptomatic femoroacetabular impingement (FAI). However, it is unclear what combined effects the cam deformity and neck angle have on acetabular cartilage and subchondral bone stresses during an impinging squat motion. We therefore used finite element analysis to examine the combined effects of cam morphology and femoral neck-shaft angle on acetabular cartilage and subchondral bone stresses during squatting, examining the differences in stress characteristics between symptomatic and asymptomatic individuals with cam deformities and individuals without cam deformities and no hip pain.

QUESTIONS/PURPOSES

Using finite element analysis in this population, we asked: (1) What are the differences in acetabular cartilage stresses? (2) What are the differences in subchondral bone stresses? (3) What are the effects of high and low femoral neck-shaft angles on these stresses?

METHODS

Six male participants were included to represent three groups (symptomatic cam, asymptomatic cam, control without cam deformity) with two participants per group, one with the highest femoral neck-shaft angle and one with the lowest (that is, most valgus and most varus neck angles, respectively). Each participant's finite element hip models were reconstructed from imaging data and assigned subject-specific bone material properties. Hip contact forces during squatting were determined and applied to the finite element models to examine maximum shear stresses in the acetabular cartilage and subchondral bone.

RESULTS

Both groups with cam deformities experienced higher subchondral bone stresses than cartilage stresses. Both groups with cam deformities also had higher subchondral bone stresses (symptomatic with high and low femoral neck-shaft angle = 14.1 and 15.8 MPa, respectively; asymptomatic with high and low femoral neck-shaft angle = 10.9 and 13.0 MPa, respectively) compared with the control subjects (high and low femoral neck-shaft angle = 6.4 and 6.5 MPa, respectively). The symptomatic and asymptomatic participants with low femoral neck-shaft angles had the highest cartilage and subchondral bone stresses in their respective subgroups. The asymptomatic participant with low femoral neck-shaft angle (123°) demonstrated anterolateral subchondral bone stresses (13.0 MPa), similar to the symptomatic group. The control group also showed no differences between cartilage and subchondral bone stresses.

CONCLUSIONS

The resultant subchondral bone stresses modeled here coincide with findings that acetabular subchondral bone is denser in hips with cam lesions. Future laboratory studies will expand the parametric finite element analyses, varying these anatomic and subchondral bone stiffness parameters to better understand the contributions to the pathomechanism of FAI.

CLINICAL RELEVANCE

Individuals with a cam deformity and more varus neck orientation may experience elevated subchondral bone stresses, which may increase the risks of early clinical signs and degenerative processes associated with FAI, whereas individuals with cam morphology and normal-to-higher femoral neck-shaft angles may be at lesser risk of disease progression that would potentially require surgical intervention.

Does Cartilage Degenerate in Asymptomatic Hips With Cam Morphology?

BACKGROUND

The management of asymptomatic individuals with cam femoral morphology that predisposes their hips to femoroacetabular impingement has received little attention. Such hips may have subclinical articular damage; however, whether this cartilage damage will progress is unknown as is whether any particular bone morphologies are associated with this progression. Such knowledge could help determine the natural history and guide management of such individuals.

QUESTIONS/PURPOSES

The purpose of this study was to determine whether (1) asymptomatic hips with cam morphology are at risk of further cartilage degeneration (as evaluated by T1ρ); (2) T1ρ changes are predictive of symptom onset; and (3) bony morphologic parameters are associated with T1ρ signal changes.

METHODS

In a prospective, longitudinal study, 17 asymptomatic volunteers/hips (16 men; 33 ± 6 years) with cam morphology underwent two T1ρ MRI scans and functional assessment (WOMAC) at recruitment and at 4 years (range, 2-6 years). Volunteers were recruited from a previous study, which reported on the prevalence of cam morphology among asymptomatic individuals using hip MRI; cam morphology was defined as an α angle ≥ 60° anterolaterally and/or ≥ 50.5° anteriorly relative to the neck axis. The differences in T1ρ values (ΔT1ρ) and relative differences (%ΔT1ρ) were calculated as: ΔT1ρ = T1ρFollowup - T1ρInitial and %ΔT1ρ = ΔT1ρ/T1ρInitial. A %ΔT1ρ > 17.6% was considered clinically important. Using CT data, femoral, acetabular, and spinopelvic parameters were measured. Whether ΔT1ρ and/or %ΔT1ρ was associated with any of the bone morphologic parameters was tested using Spearman's correlation coefficient.

RESULTS

The global T1ρ in these asymptomatic hips with cam morphology remained unchanged between initial (mean, 35 ± 5 ms) and followup scans (mean, 34 ± 3 ms; p = 0.518). No differences with the numbers available in T1ρ values were seen initially between the anterolateral and posterolateral (34 ± 6 ms versus 33 ± 4 ms; p = 0.734) regions; at followup, T1 values were higher posterolaterally (36 ± 5 ms versus 32 ± 5 ms; p = 0.031). The mean global ΔT1ρ was 1 ± 5 ms (95% confidence interval, -1 to +3 ms) and the mean global %ΔT1ρ was 2% ± 13%. Two volunteers reported lower WOMAC scores; one patient exhibited a clinically important increase in %ΔT1ρ (-26%). The degree of acetabular coverage correlated with %ΔT1ρ (rho = 0.59-0.61, p = 0.002); the lesser the acetabular coverage anterolaterally, the greater the corresponding area's T1ρ at followup.

CONCLUSIONS

Although signs of posterolateral joint degeneration were detected, these were not generally associated with symptoms, and only one of the two volunteers with the onset of symptoms had a clinically important increase in %ΔT1ρ. We found that reduced acetabular coverage may increase the likelihood that preclinical cartilage degeneration will arise within 2 to 6 years; thereby reduced acetabular coverage should be considered when stratifying asymptomatic hips at risk of degeneration. Future studies should be performed with a larger cohort and include femoral version among the parameters studied.

LEVEL OF EVIDENCE

Level II, diagnostic study.

What Is the Prevalence of Cam Deformity After Prophylactic Pinning of the Contralateral Asymptomatic Hip in Unilateral Slipped Capital Femoral Epiphysis? A 10-year Minimum Followup Study

BACKGROUND

Prophylactic pinning of the asymptomatic and normal-appearing contralateral hip in patients with unilateral slipped capital femoral epiphysis (SCFE) remains controversial. Understanding the minimal 10-year clinical, functional, and radiographic outcomes of the contralateral asymptomatic hip in unilateral SCFE may be helpful in the decision regarding whether the benefits associated with potentially preventing a SCFE are outweighed by the risk of additional surgery.

QUESTIONS/PURPOSES

Among patients with SCFE treated with prophylactic pinning of the asymptomatic and contralateral hip, we sought (1) to determine the complications and reoperations; (2) to evaluate the development of cam deformities and the frequency and severity of osteoarthritis progression; and (3) to characterize hip pain and function as measured by the Harris hip score (HHS) and the Hip Disability and Osteoarthritis Outcome Score (HOOS) at minimal 10-year followup.

METHODS

Between 1998 and 2005 all patients with SCFE seen at our institution were treated with the modified Dunn procedure and all were offered prophylactic pinning of the contralateral asymptomatic hip. Of the 41 patients who underwent the unilateral modified Dunn procedure and who had an asymptomatic contralateral hip, 37 patients (90%) underwent pinning of that contralateral hip. Of those, 33 patients (80%) were available for clinical and radiographic evaluation for this retrospective study at a minimum of 10 years (mean followup 12 ± 2 years) after surgery. Three patients of the 37 patients only had 10-year clinical followup, including questionnaires sent by mail and telephone, because they refused further radiographic followup and one patient was lost to followup. The group included 19 males and 17 females whose age at surgery was a mean of 13 ± 2 years. Medical charts were reviewed and patients were asked about complications and additional surgical procedures. Most recent postoperative radiographs were evaluated for measurement of the alpha angle, head-neck offset, epiphysis orientation, and osteoarthritis grading according to Tönnis classification and minimum joint space width. The presence of a cam deformity was defined by an alpha angle measurement > 60° on the AP radiograph and/or > 55° on the lateral radiograph. Hip function and pain were assessed by the HHS and HOOS outcome measures.

RESULTS

No complications with prophylactic in situ pinning were recorded. Four of 36 (11%) patients underwent subsequent surgical treatment for cam-type femoroacetabular impingement (FAI), and hardware removal was performed in four hips (11%). The mean alpha angle was 53° ± 8° on the AP radiograph and 49° ± 8° on the lateral view at followup. In total, 10 of 33 hips (30%) had a cam morphology at the femoral head-neck junction and four (12%) were symptomatic and underwent FAI surgery. Six of 33 patients (18%) developed an asymptomatic cam morphology at the femoral head-neck junction; in three of 33 hips (9%), the cam deformity instead of lesion were visible only on the lateral projection, and 9% were visible on both the AP and lateral projections. The preoperative offset of the femoral head-neck junction was 10 ± 3 mm on the AP view and 11 ± 4 mm on the lateral view. At followup, the AP offset was 7 ± 3 mm and the lateral offset was 6 ± 3 mm, and on the lateral view, the offset was < 10 mm in eight hips (22%). No patient had radiographic signs of hip osteoarthritis (Tönnis Grade 0). The mean minimum joint space width was 4 ± 0.4 mm. The mean HHS for the 32 patients who did not undergo subsequent surgery was 97 ± 5 at latest followup. The mean postoperative HOOS was 94 ± 8 for the 32 patients at latest followup.

CONCLUSIONS

At a minimum followup of 10 years after prophylactic pinning of a contralateral asymptomatic hip, most patients achieve excellent hip scores; however, a substantial proportion will develop a symptomatic cam deformity despite prophylactic pinning. No patient had signs of osteoarthritis at a minimum of 10 years, but almost one-third of the patients who underwent prophylactic pinning developed a cam deformity.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Relationship between crossover sign and anterior center-edge angle

Purpose

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

Methods

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

Results

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

Conclusion

A correlation exists between crossover ratio and ACEA and LCEA.