Symptomatic Femoroacetabular Impingement Research Articles

A novel radiographic finding for estimation of the cortical-cancellous boundary: A magnetic resonance imaging case series of patients with femoroacetabular impingement

PurposeTo determine if comparing alpha angle measurements of the outer cortical margin (preoperative alpha angle) and the inner cortical margin (theoretical postoperative alpha angle) on magnetic resonance imaging (MRI) can estimate the amount of sclerotic bone that needs to be resected to restore the alpha angle to normative values (<55⁰) in patients with symptomatic femoroacetabular impingement (FAI). MethodsA retrospective review was conducted on patients with FAI undergoing primary hip arthroscopy and CAM osteoplasty from June 2013 to February 2017. Inclusion criteria were radiologist-measured alpha angles >70° on 3T oblique axial MRI, unilateral primary hip arthroscopy, and age ≥18. Exclusions included previous hip surgery, hip trauma, avascular necrosis, advanced osteoarthritis, dysplasia, poor quality images, or missing MRI images. Alpha angles were measured preoperatively using the outer cortical margin and postoperatively using the inner cortical margin of femur. Surgeries were performed by the senior surgeon. Paired t-tests compared preoperative and postoperative alpha angles, and intraclass correlation coefficients (ICC) were used to assess inter-rater and intra-rater reliability. ResultsOne hundred patients (100 hips) were included with an average age of 40.8 years (range, 18.7–64.9), with 75 % being male (n = 75). The average BMI was 24.7 ± 3.9 (range, 17.1–38.8). The average maximum alpha angle at the outer cortical margin was 77.0 ± 4.2° (range, 70.0–90.8), with an ICC for inter-rater reliability of 0.861, indicating excellent agreement. The average inner cortical alpha angle was 46.4 ± 3.4° (range, 36.5–55.4), significantly less than 55° (p<0.001). The mean difference between the outer and inner cortical alpha angles was −30.6 ± 5.1° (p< 0.001). ConclusionsThe difference between outer and inner cortical alpha angles on MRI can accurately estimate the amount of sclerotic bone resection needed to restore the alpha angle to normative values in patients with FAI. This information may be directly applied clinically marker to assess adequacy of CAM resection.

Radiological predictors of outcomes in hip arthroscopy for femoroacetabular impingement.

Hip arthroscopy has gained prominence as a primary surgical intervention for symptomatic femoroacetabular impingement (FAI). This study aimed to identify radiological features, and their combinations, that predict the outcome of hip arthroscopy for FAI. A prognostic cross-sectional cohort study was conducted involving patients from a single centre who underwent hip arthroscopy between January 2013 and April 2021. Radiological metrics measured on conventional radiographs and magnetic resonance arthrography were systematically assessed. The study analyzed the relationship between these metrics and complication rates, revision rates, and patient-reported outcomes. Out of 810 identified hip arthroscopies, 359 hips were included in the study. Radiological risk factors associated with unsatisfactory outcomes after cam resection included a dysplastic posterior wall, Tönnis grade 2 or higher, and over-correction of the α angle. The presence of acetabular retroversion and dysplasia were also significant predictors for worse surgical outcomes. Notably, over-correction of both cam and pincer deformities resulted in poorer outcomes than under-correction. We recommend caution in performing hip arthroscopy in patients who have three positive acetabular retroversion signs. Acetabular dysplasia with a lateral centre-edge angle of less than 20° should not be treated with isolated hip arthroscopy. Acetabular rim-trimming should be avoided in patients with borderline dysplasia, and care should be taken to avoid over-correction of a cam deformity and/or pincer deformity.

Midterm Outcomes After Simultaneous Hip Arthroscopic Surgery for Bilateral Femoroacetabular Impingement

Background: Bilateral hip arthroscopic surgery for the treatment of femoroacetabular impingement (FAI) has demonstrated good outcomes at short-term follow-up, with significant improvements in pain, hip function, and patient-reported outcomes, coupled with a complication rate similar to that of unilateral surgery. Purpose: To investigate whether, in patients with bilateral symptomatic FAI, simultaneous bilateral hip arthroscopic surgery is an efficacious option that produces effective midterm outcomes. Study Design: Cohort study; Level of evidence, 3. Methods: A prospective database of patients who underwent primary hip arthroscopic surgery between August 2012 and October 2020 was used to collect clinical data on 2 groups. Group 1 consisted of patients who underwent simultaneous bilateral hip arthroscopic surgery for the treatment of FAI. Group 2 represented a matched-pair control group of patients selected based on sex and age with signs and symptoms of unilateral FAI and in whom a single side was evaluated and treated. Differences in the International Hip Outcome Tool–12 and Non-Arthritic Hip Score scores were evaluated up to 5 years postoperatively. Results: In total, 171 patients (235 hips) were included, of whom 64 underwent simultaneous bilateral hip arthroscopic surgery (128 hips) and a control group of 107 patients (107 hips) underwent unilateral hip arthroscopic surgery. No significant differences were observed in International Hip Outcome Tool–12 scores between the 2 groups at 6 weeks, 3 months, 1 year, 2 years, and 5 years postoperatively. No significant differences were observed in Non–Arthritic Hip Score scores between the simultaneous bilateral and control groups at 6 weeks, 3 months, 6 months, 1 year, 2 years, and 5 years postoperatively. Overall, 18% of hips in the simultaneous bilateral group reported lateral femoral cutaneous nerve palsy at 2-week follow-up in comparison to 16% of hips in the control group. Conclusion: Simultaneous bilateral hip arthroscopic surgery for the treatment of FAI represents a safe treatment option, producing effective midterm outcomes in appropriately selected patients.

Poster 189: Does Patient Resiliency Influence Patient-Reported Outcomes at Presentation in Symptomatic Femoroacetabular Impingement?

Objectives: The role of psychological factors in the clinical presentation and outcomes of treated is increasingly recognized in orthopaedic surgery. Particularly, in prearthritic hip disorders, young adult hip patients often have significant psychological undertones. Patient resiliency, as quantified by the brief resiliency scale (BRS), is a static patient characteristic and has been increasingly recognized for its potential role in pain and symptomatology. The purpose of the current study was to investigate the correlation between BRS and traditional hip patient-reported outcome measures (PROMs). Methods: A prospective multicenter cohort study of 696 patients undergoing femoroacetabular impingement (FAI) primary hip arthroscopy surgery was performed and utilized for the current study. Inclusion criteria are patients aged 14 to 45 years old with idiopathic FAI not caused by childhood disease. Exclusion criteria are previous ipsilateral hip procedures or disease processes such as neuromuscular disease or high-grade osteoarthritis. PROMs included the Patient-Reported Outcomes Measurement Information System (PROMIS) domains of pain interference, physical function, mobility, anxiety, and depression, as well as hip disability and osteoarthritis and outcome score (HOOS), modified Harris hip score (mHHS), international hip outcome tool (iHOT-12), and short form-12 (SF-12). Resiliency was divided into low resiliency (score &lt; 3), normal resiliency (score 3 to 4.3), and high resiliency (score &gt; 4.3) as described by Smith et al1 to use as categorical variables to compare to the other patient-reported scores. The Pearson correlation coefficient (r) was calculated and the Kruskall Willis test was used to measure association between BRS and the other PROMs for continuous and categorical values, respectively. R values ≥0.7, ≥0.4, and ≥0.1 signify a strong, moderate, and weak correlation, respectively. For categorical analysis, P values &lt; 0.05 were considered significant. Results: The cohort of 696 patients had mean age was 24.9 ± 7.9 years and a female predominance at 56%. Average BRS scores were 3.7 ± 0.7. Overall, 13.7% of patients had low resiliency, while 65.8% had normal resiliency and 20.5% had high resiliency. Linear correlation, using Pearson coefficients, found associations between BRS and all other scores. There were only weak associations between BRS scores and PROs (all r &lt; 0.25) except a moderate correlation with PROMIS depression (r = -0.476, p &lt; 0.001) and PROMIS anxiety (r = -0.481, p &lt; 0.001). Patients in higher resiliency groups reported less severe symptoms in HOOS – quality of life (p &lt; 0.001), HOOS – sports and recreation (p = 0.004), HOOS – activities of daily living (p = 0.004), HOOS – pain (p = 0.026), iHOT-12 (p = 0.01), mHHS (p = 0.004), SF-12 mental (p &lt; 0.001), PROMIS physical function (p = 0.003), PROMIS pain (p &lt; 0.001), PROMIS mobility (p &lt; 0.001), PROMIS depression (p &lt; 0.001), and PROMIS anxiety (p &lt; 0.001). Patients with higher activity levels (UCLA ≥9) demonstrated higher resiliency (p = 0.04). Conclusions: In FAI patients, patient resiliency appears to influence baseline PROs. Overall, 14% of patients had low resiliency while 21% had high resiliency. Further studies are needed to investigate this relationship and whether concurrent psychological treatment will help improve patient outcomes after hip arthroscopy for FAI. [Figure: see text]

Poster 199: High Prevalence of Elevated Beighton Scores in Females Undergoing FAI Surgery

Objectives: Femoroacetabular impingement (FAI) is classically described as restricted internal rotation in flexion resulting in labral and cartilage pathology. Despite 20 years of FAI research, there is still limited understanding of the drivers of symptomatology in the subset of patients with underlying FAI morphology. While the prevalence of FAI morphologies is substantially higher in men, numerous studies have shown more women being treated for FAI compared to men. Soft-tissue laxity and hip instability are increasingly recognized as a potential contributor to symptoms in addition to FAI. The Beighton score is a well-accepted means to quantify soft-tissue laxity and has been validated for self-scoring. The purpose of the current study was to (1) investigate the prevalence of soft-tissue laxity in male and female patients presenting with symptomatic FAI in a multicenter prospective cohort study, and (2) correlate soft-tissue laxity with patient primary complaints of either mobility, stability, or pain. Methods: A prospective multicenter cohort study of 696 FAI patients undergoing primary hip arthroscopy surgery was performed and utilized for the current study. Inclusion criteria are patients aged 14 to 45 years old with idiopathic FAI not caused by childhood disease. Exclusion criteria are previous ipsilateral hip procedures or disease processes such as neuromuscular disease or Tonnis 2 or greater osteoarthritis. The Beighton score was assessed by electronic patient self-scoring. Beighton scores &gt;4 were considered a marker of soft-tissue laxity. The MSP index was utilized to have patients rank from most to least the biggest problems with their hip: Mobility (M), Stability (S), or Pain (P). The chi-square or Fisher exact test were utilized to compare groups. Results: The prevalence of Beighton scores &gt;4 was 57.2% in female patients, compared to 29.3% in male patients (p &lt; 0.001). In female patients, 44.4%, 22.6%, and 7.7% had Beighton scores of 5+, 7+, and 9 respectively, compared to 16.7%, 5.8%, and 1.8% in male patients (all p &lt; 0.005). In the overall FAI cohort, pain was the primary complaint in 72.1% of patients, compared to 24.2% complaining primarily of mobility and 3.7% complaining primarily of stability. Among female patients, the presence of soft-tissue laxity (relative to thresholds of Beighton 4, 5, 7, and 9) did not significantly influence the patient primary complaints (with pain being the predominant complaint). Overall, 85 female patients had a Beighton score of 7 or greater and only 2.4% reported stability of the hip as a primary complaint, compared to 2.4% of female patients with a Beighton &lt;7. Stability was more commonly indicated as a second most important factor in the setting of soft-tissue laxity, compared to mobility. Among female patients with a Beighton &gt;7, 29.5% reported stability as a primary or secondary complaint, compared to 15.2% of female patients with a Beighton score &lt;7. Conclusions: Over half of female patients undergoing FAI surgery have underlying soft-tissue laxity as measured by the Beighton score. In the setting of soft-tissue laxity, patient primary symptomatic complaint remains pain, but a secondary complaint is significant more likely to be stability rather than mobility (compared to FAI patients without soft tissue laxity complain of mobility secondarily over stability). Further research is needed to better understand the role of soft-tissue laxity in the pathophysiology of FAI and the outcomes of surgical treatment.

Mid-term results of autologous matrix-induced chondrogenesis for large chondral defects in hips with femoroacetabular impingement syndrome.

The purpose of this study was to evaluate the mid-term outcomes of autologous matrix-induced chondrogenesis (AMIC) for the treatment of larger cartilage lesions and deformity correction in hips suffering from symptomatic femoroacetabular impingement (FAI). This single-centre study focused on a cohort of 24 patients with cam- or pincer-type FAI, full-thickness femoral or acetabular chondral lesions, or osteochondral lesions ≥ 2 cm2, who underwent surgical hip dislocation for FAI correction in combination with AMIC between March 2009 and February 2016. Baseline data were retrospectively obtained from patient files. Mid-term outcomes were prospectively collected at a follow-up in 2020: cartilage repair tissue quality was evaluated by MRI using the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score. Patient-reported outcome measures (PROMs) included the Oxford Hip Score (OHS) and Core Outcome Measure Index (COMI). Clinical examination included range of motion, impingement tests, and pain. A total of 12 hips from 11 patients were included (ten males, one female, mean age 26.8 years (SD 5.0), mean follow-up 6.2 years (SD 5.2 months)). The mean postoperative MOCART score was 66.3 (SD 16.3). None of the patients required conversion to total hip arthroplasty. Two patients had anterior impingement. External hip rotation was moderately limited in four patients. There was a correlation between MOCART and follow-up time (rs = -0.61; p = 0.035), but not with initial cartilage damage, age, BMI, or imaging time delay before surgery. PROMs improved significantly: OHS from 37.4 to 42.7 (p = 0.014) and COMI from 4.1 to 1.6 (p = 0.025). There was no correlation between MOCART and PROMs. Based on the reported mid-term results, we consider AMIC as an encouraging treatment option for large cartilage lesions of the hip. Nonetheless, the clinical evidence of AMIC in FAI patients remains to be determined, ideally in the context of randomized controlled trials.

PATIENTS WITH FEMOROACETABULAR IMPINGEMENT SYNDROME OBTAIN SIGNIFICANT AND SUSTAINED IMPROVEMENT FOLLOWING A COMBINED HIP INJECTION AND REHABILITATION PROGRAM

INTRODUCTION Initial treatment recommendations for symptomatic femoroacetabular impingement syndrome include non-surgical therapies such as injections and rehabilitation. However, many patients undergo isolated injections or a rudimentary exercise regime. This study investigated the benefit of a combined intra-articular hip injection and structured exercise rehabilitation program in patients with FAIS. METHODS Participants were recruited and underwent a guided intra-articular injection of corticosteroid and local anaesthetic, followed by a 12-week rehabilitation program. Patients were assessed pre-and post-injection(8 weeks, 4, 6, 12 and 24 months) via patient-reported outcome measures including the 33-item International Hip Outcome Tool and Hip Outcome score. Hip ROM and peak isometric hip strength in all planes were assessed, along with single-limb hop capacity. Limb Symmetry Indices were calculated. The percentage of patients transitioning toward surgery over the period was evaluated. RESULTS A total of 44 patients underwent the injection and completed the initial 8-week rehabilitation component. A significant improvement (p&amp;lt;0.05) in all PROMs was observed, with 93% of patients satisfied. A significant increase (p&amp;lt;0.05) in all active hip ROM and isometric strength measures was observed, sustained over the 24-month period. Bilateral improvements in hop capacity were observed, with all hop test LSIs significantly improving (p&amp;lt;0.05). Overall, 14 patients (32%) progressed toward surgical intervention over the 24-month post-injection period. These patients reported significantly worse (p&amp;lt;0.05) PROMs pre-surgery and more pain within the first 4 weeks post-injection. CONCLUSION This is the first study seeking to implement and comprehensively assess a best-practice, multimodal non-operative program consisting of an intra-articular injection and a structured exercise program. Most patients with symptomatic FAIS demonstrated significant improvement in symptoms.

Hip Arthroscopy Improves Sexual Function in Receptive Partners with Femoroacetabular Impingement Syndrome.

Hip Arthroscopy Improves Sexual Function in Receptive Partners with Femoroacetabular Impingement Syndrome.

Clinical Outcomes After Arthroscopic Treatment of Extraspinal Diffuse Idiopathic Skeletal Hyperostosis (DISH) Involving the Hip Joint.

The hip joint can be affected by extraspinal diffuse idiopathic skeletal hyperostosis (DISH). This study aimed to compare the clinical characteristics of hips with DISH to those with mixed-type femoroacetabular impingement symptoms (FAIS). In addition, patient-reported outcome (PRO) scores were reported among patients with DISH involving the hip joint who underwent arthroscopic treatment. A retrospective analysis was performed using data from patients who underwent hip arthroscopy between 2017 and 2021. Patients who had a preoperative diagnosis of extraspinal DISH of the hip joint and postoperative Hip Outcome Score-Activities of Daily Living (HOS-ADL), Hip Outcome Score-Sports Subscale (HOS-SSS), International Hip Outcome Tool 12-component form (iHOT-12), modified Harris Hip Score (mHHS) and visual analog scale (VAS) for pain scores were enrolled in the study. The patients' characteristics were compared with those of a control group (1:2) consisting of mixed-type patients with FAIS. The control group was matched in terms of age, sex, body mass index (BMI), and symptom duration. Eleven hips (0.87%) with extraspinal DISH (study group) were matched to 22 FAIS hips (control group). All the patients were male. The mean age of patients was 42.0 ± 8.0 in the study group. The study group was characterized by a larger preoperative alpha angle (79.1 ± 6.8 vs 64.8 ± 9.7, P < .001), lateral center-edge angle (LCEA) (49.7 ± 6.0 vs 40.7 ± 3.2, P < .001), and postoperative LCEA (36.6 ± 3.0 vs 34.2 ± 2.0, P = .013). In addition, a higher proportion of acetabular (81.8% vs 31.8%, P = .007) and femoral head chondral lesions (45.5% vs 9.1%, P = .016). Cartilage damage has the potential to affect the prognosis of arthroscopic treatment. Nevertheless, at the final follow-up, patients with DISH experienced a significant increase in range of motion (ROM), notable enhancements in all PROs, and favorable rates of minimal clinically important difference (MCID) for the PROs. The occurrence of DISH in the hip joint is considerably infrequent, characterized by hip pain and limited ROM. Despite increased alpha angle and LCEA, and more acetabular and femoral head chondral damage noted at the time hip arthroscopy, patients with DISH observed a significant improvement in ROM, notable enhancements in all PROs, and favorable rates of MCID for the PROs.

Comparison of MRI and arthroscopy findings for transitional zone cartilage damage in the acetabulum of the hip joint.

To assess the performance of morphologic and hypointense signal changes on MRI to predict grades and types of acetabular cartilage damage in the chondrolabral transitional zone (TZ) of the hip identified at arthroscopy. This retrospective single-center study reviewed conventional 3T MRI hip studies from individuals with symptomatic femoroacetabular impingement (FAI) and subsequent hip arthroscopy surgery within 6 months. Independent review was made by three radiologists for the presence of morphologic damage or a hypointense signal lesion in the TZ on MRI. Fleiss' kappa statistic was used to assess inter-reader agreement. The degree of TZ surfacing damage (modified Outerbridge grades 1-4) and presence of non-surfacing wave sign at arthroscopic surgery were collected. Relationship between sensitivity and lesion grade was examined. One hundred thirty-six MRI hip studies from 40 males and 74 females were included (mean age 28.5 years, age range 13-54 years). MRI morphologic lesions had a sensitivity of 64.9-71.6% and specificity of 48.4-67.7% for arthroscopic surfacing lesions, with greater sensitivity seen for higher grade lesions. Low sensitivity was seen for wave sign lesions (34.5-51.7%). MRI hypointense signal lesions had a sensitivity of 26.3-62% and specificity of 43.8-78.0% for any lesion. Inter-reader agreement was moderate for morphologic lesions (k = 0.601) and poor for hypointense signal lesions (k = 0.097). Morphologic cartilage damage in the TZ on MRI had moderate sensitivity for any cartilage lesion, better sensitivity for higher grade lesions, and poor sensitivity for wave sign lesions. The diagnostic value of hypointense signal lesions was uncertain.

Association of Idiopathic Cam Morphology With Femoral and Acetabular Version: Analysis of 986 Cadaveric Hips.

Studies have correlated symptomatic femoroacetabular impingement (FAI) with femoral retroversion and cam lesions. To investigate any association between femoral and acetabular versions with cam deformity in a largely asymptomatic population. Descriptive laboratory study. A total of 986 cadaveric hips were selected from a historical osteologic collection. Each hip was assessed to determine the femoral and acetabular versions, anterior offset, and alpha angle. Cam morphology was defined as an alpha angle >60°. Multiple regression analysis was performed to determine the relationship between age, femoral version, acetabular version, and either alpha angle or anterior femoral offset. The mean alpha angle and anterior offset for the sample population were 48.1°± 10.4° and 0.77 ± 0.17 cm, respectively, with cam morphology in 149 of the 986 (15.1%) specimens. No significant difference was observed between hips with and without cam morphology with respect to the femoral (10.8°± 10° vs 10.3°± 9.6°; P = .58) or acetabular versions (17.4°± 6° vs 18.2°± 6.3°; P = .14). Multiple regression analysis did not demonstrate an association between the femoral or acetabular versions and the alpha angle, and it showed a small association between the increasing femoral and acetabular versions and a decreased anterior femoral offset (both P < .01). In a large random sample of cadaveric hips, cam morphology was not associated with femoral or acetabular retroversion. Combined with the existing literature, these findings suggest that retroversion is not associated with cam development. This study provides insight into the development of cam morphology, which may eventually aid in the evaluation and treatment of FAI.

Soft Tissue Cam Impingement in Adolescents: MRI Reveals Impingement Lesions Underappreciated on Radiographs

Background: Femoroacetabular impingement (FAI) has been described as repetitive and abnormal contact between a structurally abnormal proximal femur (cam) and/or acetabulum (pincer), occurring during the terminal range of motion of the hip. While cam and pincer lesions have traditionally been defined as osseous abnormalities, there may be a subset of adolescent patients whose impingement is primarily soft tissue (nonosseous). The existence of a nonosseous cam lesion in adolescents with FAI has not been well described. Purpose: To identify and characterize a series of adolescent patients with nonosseous (soft cam) FAI identified on magnetic resonance imaging (MRI) and compare these patients’ clinical presentation and outcome with those of a cohort with primary osseous cam FAI in the same age group. Study Design: Case series; Level of evidence, 4. Methods: A prospective institutional registry of patients with symptomatic FAI was reviewed. Patients were included if they had an MRI scan and a lateral radiograph of the hip (45° Dunn or frog) at a baseline visit. On MRI, the anterolateral femoral head was evaluated using radial, coronal, sagittal, or axial oblique sequences. A soft cam lesion was identified by the presence of soft tissue thickening of ≥2 mm at the anterolateral femoral head-neck junction. An alpha angle was measured on MRI scans and radiographs when a lesion was identified. The cohort with soft cam lesions was reviewed and findings and outcomes were compared with those of a cohort with osseous cam lesions. Continuous variables were first examined for normality, and then nonparametric tests—such as the Kruskal-Wallis test—were considered. The change between pre- and postoperative patient-reported outcomes (PROs) was described by mean and standard deviation and evaluated with an independent-samples t test. Results: A total of 31 (9.3%) of 332 hips (mean age, 16.4 years [range 13.1-19.6 years]; women, 83.9%) were identified with a soft tissue impingment lesion on MRI at the femoral head-neck junction between the 12 and 3 o'clock positions. These lesions demonstrated a thickened perichondral ring (71%), periosteal thickening (26%), or a cartilaginous epiphyseal extension (3%). The mean alpha angle on MRI was greater than on radiographs (63.5°± 7.9° vs 51.3°± 7.9°; P < .0001). A total of 22 patients (71%) with soft impingement underwent hip preservation surgery. When compared with patients in the osseous cohort who also underwent surgical management, both groups showed similar significant improvements from pre- to postoperatively (soft: modified Harris Hip Score [mHHS], 26.9 ± 18.2; Hip disability and Osteoarthritis Outcome Score [HOOS], 31.4 ± 22.9; osseous: mHHS, 22.8 ± 20.8; HOOS, 27.4 ± 20.1; P < .0001), with a mean follow-up of 3.4 years (range, 1-7 years) in the soft cam cohort and 3 years (1-10.1 years) in the osseous cam cohort. Conclusion: Clinicians should be aware of nonosseous or soft cam lesions that cause impingement in adolescent patients without an obvious osseous cam on radiographs. MRI is required to detect these soft cam lesions. When nonoperative treatment fails, the PROs in these patients after operative management are comparable with those in patients with osseous cam lesions. Further research is needed to determine whether the soft cam precedes an osseous cam or whether it is a separate entity.

Differences in Kinematic Changes From Self-Selected to Fast Speed Gait in Asymptomatic Adults With Radiological Signs of Femoro-Acetabular Impingement.

Femoro-acetabular impingement (FAI) may present as alterations in the skeletal morphology of the hip. Repercussions of FAI can be witnessed in self-selected speed walking as well as physical exercise such as running or fast speed walking. The aim of this study was to investigate changes in kinematics at different gait speeds in subjects presenting with radiological findings invoking FAI. One hundred thirty asymptomatic adults underwent biplanar X-rays with a calculation of 3D hip parameters: acetabular anteversion, abduction and tilt, vertical center edge angle (VCE), femoral anteversion, neck-shaft angle, acetabular coverage of the femoral head, femoral head diameter and neck length. Parameters were classified according to FAI clinical thresholds. Two groups were created: Control group (63 subjects having up to one subnormal hip parameter in favour of FAI) and Radiographic FAI group (67 subjects having ≥2 subnormal hip parameters that might cause FAI). All subjects underwent 3D gait analysis at self-selected and fast speed, from which kinematic parameters were generated. Arithmetic differences between fast and self-selected speed gait were considered as gait changes. Subjects in the Radiographic FAI group had decreased acetabular tilt (24 vs. 19˚), anteversion (19 vs. 16˚), abduction (55 vs. 53˚), femoral anteversion (18 vs. 14˚) and increased VCE (29 vs. 33˚, all p<0.05), compared to controls.Changes from self-selected to fast speed showed that subjects in the Radiographic FAI group had lower range of motion (ROM) pelvic rotation (7 vs. 4˚) and ROM hip flexion/extension (10 vs. 7˚), reduced hip extension (-4 vs. -2˚) and step length (16 vs. 13 cm; all p<0.05). The Radiographic FAI group had decreased acetabular abduction, anteversion and femoral anteversion in favour of FAI. When adapting from self-selected to fast speed gait, the Radiographic FAI group seemed to limit pelvic rotation and hip flexion/extension resulting in a decrease in step length. These kinematic limitations were previously reported in subjects with symptomatic FAI. Gait analysis could be considered as a functional diagnostic tool to assess FAI along with radiological assessment.

Progression of Osteoarthritis at Long-term Follow-up in Patients Treated for Symptomatic Femoroacetabular Impingement With Hip Arthroscopy Compared With Nonsurgically Treated Patients

Background: Femoroacetabular impingement (FAI) is a common cause of hip pain, especially in young patients. When left untreated, it has been demonstrated to be a risk factor for the onset or progression of osteoarthritis (OA) and has been identified as one of the main contributors leading to the need for total hip arthroplasty (THA) at a young age. While the short-term therapeutic potential of hip arthroscopy is widely recognized, little is known regarding its potential mid- to long-term preventive effect on the progression of hip OA. Purpose: To (1) report clinical outcomes of arthroscopically treated FAI syndrome with a minimum 5-year follow-up and compare the results to a cohort with FAI treated nonsurgically and (2) determine the influence of hip arthroscopy on the onset and progression of hip OA in patients diagnosed with FAI. Study Design: Cohort study; Level of evidence, 3. Methods: Patients who had hip pain and were diagnosed with FAI were included. Exclusion criteria were (1) previous or concomitant hip surgery, (2) <5 years of follow-up, and (3) insufficient radiographs. Patients treated with hip arthroscopy were compared with a cohort of patients with FAI who were treated nonsurgically. Kaplan-Meier estimates of failure (defined as conversion to THA) were performed. Bivariate analysis and Cox regression were used to identify factors associated with inferior clinical and radiographic outcomes. Results: A total of 957 patients (650 female, 307 male; 1114 hips) (mean age, 28.03 ± 8.9 years [range, 6.5-41.0 years]) with FAI were included. A total of 132 hips underwent hip arthroscopy and 982 hips were nonoperatively treated. The mean follow-up was 12.5 ± 4.7 years (range, 5.0-23.4 years). At the final follow-up, the rate of OA progression was 26.5% in the operative group and 35.2% in the nonoperative cohort (P < .01). Conversion to THA was performed in 6.8% of the surgical patients and 10.5% of the initially nonsurgical patients (P = .19). Additionally, there was no significant difference in the risk of failure between the operatively and nonoperatively treated patients. Male sex, increased age at initial diagnosis, presence of cam morphology, and increased initial Tönnis grade were risk factors for failure (male sex: hazard ratio [HR], 2.3; P < .01; per year of increased age: HR, 1.1; P < .01; presence of cam: HR, 3.5; P < .01; per Tönnis grade: HR, 4.0; P < .01). Conclusion: At a mean follow-up of nearly 13 years, 7% of patients of the surgical group experienced progression to THA, compared with 11% of the nonoperative control group. While most of the operative group showed little to no OA at final follow-up, moderate OA (Tönnis grade 2) was present in 12% of the cohort compared with 22% of nonsurgical patients. Increased age at diagnosis, male sex, presence of a cam morphology, and presence of initial arthritic joint changes were found to be risk factors for failure. The results of this study demonstrated evidence for a preventive effect of hip arthroscopy on the development and progression of OA in young patients with FAI at mid- to long-term follow-up.

Poster 212: Return to Sport Rate of Collegiate Athletes Following Primary Hip Arthroscopy for Femoroacetabular Impingement

Objectives: Athletic participation has been increasingly associated with symptomatic femoroacetabular impingement (FAI). High-intensity and repetitive sporting activities, especially those involving “at-risk” hip positions, can increase the risk for developing FAI. Numerous studies have shown that elite athletes can return to play at the professional level after undergoing hip arthroscopy. However, there is minimal data on return to sport rate and outcomes at the collegiate level. The purpose of this study is to determine the return to sport (RTS) rate of collegiate athletes following hip arthroscopy for treatment of FAI. Methods: Patients who were collegiate athletes and underwent hip arthroscopy surgery for treatment of FAI performed by a single surgeon between January 2010 and May 2020 were included. Patients who were in their final year of eligibility, graduated, retired or had plans to retire from collegiate play prior to surgery, or who had undergone prior ipsilateral hip surgery were excluded. Publicly available data was collected on each patient’s collegiate team and division, RTS status after surgery, and level of play after surgery. Successful RTS was defined as competing in a competition at the collegiate level after surgery. If both hips were operated on during the same season, then RTS was the same for both hips. Comparisons between RTS and no RTS groups were performed with the Mann-Whitney U test for continuous endpoints and Fisher’s exact test or Pearson’s Chi-squared test for categorical or binary endpoints. Results: A total of 181 hips (in 148 unique athletes) met inclusion criteria comprised of 114 male (63%) and 67 female (37%) hips with mean age of 20.5±1.5 (Table 1). Thirty-eight patients had bilateral hip arthroscopy. Patients were collegiate athletes in 19 different sports with football (17% of hips), soccer (15%), ice hockey (14%), and baseball (8%) the most commonly played (Table 2). The majority of patients played at the Division I level (n=140 hips, 79%). There were 19 patients with borderline dysplasia (lateral center-edge angle (LCEA)=20-25 degrees) and 7 patients with dysplastic hips (LCEA &lt;20 degress). Severe cartilage defects (Outbridge III/IV) were found in 41 hips (23%) with 15 hips (8%) undergoing microfracture. Eighty-six percent (155 hips) returned to sport at the collegiate level following hip arthroscopy. Males were significantly less likely to RTS compared to females (82% vs 93%, OR = 2.8, 95% CI [1.003, 7.819], p=0.042). Patients who RTS did have a marginally statistically significantly higher mean pre-operative SF-12 MCS compared to those who did not (55±9 vs 51±9, p=0.050). There was no signficiant association between the RTS and no RTS groups with respect to preoperative alpha angle, minimum joint space, LCEA or dysplasia category, collegiate division, presence or treatment of severe cartilage defect, or pre-operative outcome scores relating primarily to pain or physical function (mHHS, HOS-ADL, HOS-Sport, SF-12 PCS) (p&gt;0.05 for all). Conclusions: There is a high return to sport rate among collegiate athletes following hip arthroscopy for the treatment of FAI. Male athletes and those with lower preoperative SF-12 MCS scores may be at risk for lower likelihood of return to collegiate competition. [Table: see text][Table: see text]

Excessive Femoral Anteversion Leading to Symptomatic Posterior Femoroacetabular Impingement, Cam Deformity of the Posterior Femoral Head-Neck Junction, and Anterior Hip Instability in a Dancer: A Case Report.

An adolescent female dancer with excessive femoral anteversion presented with posterior and anterior hip pain aggravated by poses that required extension and external rotation. Imaging revealed an atypical cam deformity of the posterior head-neck junction. During surgery, the posterior head-neck junction was observed to impinge on the posterior acetabulum with anterior subluxation of the hip. After a derotational femoral osteotomy, the patient experienced resolution of her symptoms. Excessive femoral anteversion can lead to reactive cam deformity, posterior intra-articular impingement, and anterior hip instability in patients who require repetitive hip extension and external rotation, such as ballet dancers.

Poster 113: Epigenetic Regulation of PPARγ Rescues Articular Chondrocytes from Catabolic State Suggesting PPARγ as a Potential Target to Slow Down Progression of OA in Hip FAI

Objectives: Hip Femoroacetabular impingement (FAI) has a high prevalence of chondral lesions, and the severity of chondral damage is associated with an increased risk of postoperative OA progression, but the mechanisms of cartilage degeneration in OA progression remains unclear. Peroxisome proliferator- activated receptor-gamma (PPARγ) is widely expressed in healthy articular chondrocytes (ACs) and plays an essential role in cartilage homeostasis. Recent investigations into OA pathogenesis have revealed that hyper or hypomethylation (by DNMTs) of OA susceptibility genes are involved in OA progression, especially downregulation of PPARγ has been linked to OA progression. This study aimed to investigate the expression of PPARγ and DNA methyltransferases enzymes (DNMT1 and DNMT3A) during progression of hip disease and 2) methylation changes in the PPARγ promoter area during progression of hip disease. Methods: Full-thickness cartilage samples were collected from the impingement zone. Twelve patients underwent hip preservation surgery for cam FAI (early FAI) and twelve patients underwent total hip replacement for advanced OA secondary to cam FAI (late FAI-OA) were included. As a non-disease (ND) group, six healthy samples were procured from hip joint cadavers. Cartilage explants were cultured in unstimulated conditions or catabolic stimulus (IL1β) with or without DNA demethylating agent 5-Aza-2’- deoxycytidine (5Aza). Histological analysis was performed with safranin O/fast green. Gene expression was analyzed via qPCR for GAPDH, DNMT1, DNMT3A, PPARγ, MMP13, and COL10A1. Methylation specific PCR (MSP) was performed to assess the methylation status at PPARγ promoter site. Chromatin immunoprecipitation (ChIP) assay was performed to confirm an interaction between DNMT3A and the PPAR promoter region. Results: The early FAI group included younger subjects than the late FAI OA group. Cartilage samples in early and late FAI-OA displayed a histological OA phenotype (Figure 1A). ACs in early and late FAI-OA displayed increased expression of catabolism and chondrocyte hypertrophy markers ( MMP13: ND vs early p&lt;0.001, ND vs late p&lt;0.001, COL10A1: ND vs early p&lt;0.001, ND vs late p&lt;0.001, Figure. 1B). Contrary, expression of PPARγ gradually declined as the disease progressed (ND vs early p=0.001, early vs late p=0.003, Figure. 1B). IF analysis also displayed a gradual decrease of the PPARγ expression during disease progression (ND vs early p=0.001, early vs late p=0.041, Figure 1C). In the assessment of the epigenetic mechanisms of aberrant DNA methylation in OA progression, overexpression of DNMT1 and DNMT3A levels was observed with disease progression in RT-PCR ( DNMT1: ND vs early p&lt;0.001, early vs late p=0.041, DNMT3A: ND vs early p=0.015, early vs late p=0.053,Figure 2A) and IF analysis ( DNMT1: ND vs early p&lt;0.001, early vs late p&lt;0.001, DNMT3A: ND vs early &lt;0.001, early vs late p=0.008, Figure 2B). Next, in MSP analysis, human PPARγ promoter was featured by typical CpG islands (Figure 3A). As the OA progresses, hypermethylation at PPARγ promoter (ND: 9%, Early-FAI: 34%, Late FAI-OA: 48%) was observed (Figure 3B), and ChIP assay confirmed DNMT3A interaction with the CpG PPARγ promoter area (Figure 3C). IL1β stimulus increased PPARγ promoter methylation for early (34% to 57%, p=0.016, Figure 3D) and late stages (48% to 79%, p=0.001, Figure 3D) resulting in suppression of PPARγ expression (P=0.073, Figure 3F). Contrary, treatment with 5Aza (a DNA demethylator) brought the level of methylation back to 37% for early FAI ( p=0.033, Figure 3D) and 46% for late FAI-OA (p&lt;0.001, Figure 3D), reversed the PPARγ suppression induced by IL1β (early- FAI p=0.009, and late FAI-OA ACs p&lt;0.001 Figure 3F) and decreased expression of MMP-13 and COL10A1 induced by IL1β (early-FAI p=0.009, Figure 4C and late FAI-OA ACs p&lt;0.001 Figure 3F). PPARγ inhibitor rescued cells from the catabolic phenotype. (Fig.3E, F), suggesting that restoration of PPARγ by 5Aza contributes significantly to the cartilage protective effect. Conclusions: This current study demonstrates that PPARγ expression was gradually suppressed via promoter hypermethylation during OA progression in hip FAI. Moreover, the inflammatory stimulus with IL1β further increased catabolic markers and enhanced PPARγ suppression via promoter excessive hypermethylation in human hip ACs. Notably, DNA demethylating agent (5 aza) prevents the IL1β induced PPARγ promoter hypermethylation rescuing PPARγ and alleviating cartilage degenerative damage. Certainly, for patients with symptomatic hip FAI, surgical correction should be prioritized to suppress inflammation, but our observations suggests that critical epigenetic dysregulation occurs during the progression of hip OA. Future investigations will be needed to confirm if regulation of these epigenetic changes could potentially complement surgical treatment to minimize OA progression in hip FAI.

Paper 11: Hip Cartilage Defects in Elite Athletes: Their Association with Specific Sports and ‘At-risk’ Motions

Objectives: Chondral injuries, especially in high-level athletes, can have drastic functional detriments. Much of the prior work on osteochondral injury has studied the knee, however emphasis on the hip has emerged with advances in hip preservation techniques. While hip chondral defects have been shown to be associated with femoroacetabular impingement (FAI), a more in-depth understanding of the determining factors is needed due to the limited spontaneous repair capacity of cartilage. It is currently unclear if the type of sport or specific motions are related to the prevalence or severity of chondral defects seen in athletes. The purpose of this study is to evaluate the prevalence of chondral defects across specific sports and characterize the corresponding articular cartilage injury patterns in the hip, as found in elite and professional athletes. Methods: Elite athletes at least 18 years old, defined as those competing in college or professionally, who underwent arthroscopy for symptomatic FAI by a single surgeon between January 2005 and November 2018 were considered for inclusion. A review of records was performed of all the patients’ operative information was reviewed from the patient records database, including operative reports, operative photos, and extensive operative details. Exclusion criteria consisted of prior ipsilateral hip surgery, presence of osteoarthritis (joint space &lt; 2 mm), history of confounding injury or prior hip conditions. Patients were then classified by their sport using a classification system based on ‘at-risk’ hip motions (rotational, repetitive, extreme, contact, and high-speed). Prevalence, size, severity (Outerbridge grade), and location of chondral defects were compared. Results: The cohort consisted of a total of 431 hips (107 female, 324 male, mean age 26.8 ± 5.1) of elite athletes, representing 24 sports at various elite levels of play. Chondral defects (grade I-IV) were found in 408 (95%) of cases. Severe chondral defects (grade III/IV) were seen in 218 (51%) of cases and most commonly found in football, soccer, and baseball players. Microfracture was performed in 72 (17%) of total cases. There was significantly higher prevalence of acetabular (p=.046), femoral head (p=.038), and combined (p=.035) grade III/IV lesions in the rotational versus non-rotational group, as well as acetabular (p=&lt;.001) and combined (p=.018) grade III/IV lesions in the contact sport group versus non-contact group. Non-high speed sports (p=0.029) had significantly higher percentages of femoral head grade III/IV lesions compared to non-high speed, and non-extreme ranges of motion sports (p=0.002) had higher rates of grade III/IV lesions compared to extreme range of motion sports. Conclusions: In elite athletes, the prevalence of chondral defects was high when undergoing hip arthroscopy. The severity, size, and location varied based on type of motion and stress on the hip that was determined by the sport. The more severe (grade III/IV) defects were more common in the rotational and contact athletes according to the motion classification system. The nature of high speed and extreme range of motion sports may be somewhat protective or select-out for athletes with hip chondral defects. This classification system can be used to identify athletes at risk of chondral damage for close monitoring and injury prevention. This information can also be used to pre-operatively counsel these athletes on the likely findings and to set expectations. This can also inform the discussion as to timing of surgery for rehabilitative purposes and athletic career management. [Table: see text][Table: see text]

DOES BONE TURNOVER EXPLAIN HIGH BONE DENSITY IN FEMOROACETABULAR IMPINGEMENT? AN ANALYSIS OF PET AND CT IMAGING

Femoroacetabular impingement (FAI) results from a morphological deformity of the hip and is associated with osteoarthritis (OA). Increased bone mineral density (BMD) is observed in the antero-superior acetabulum rim where impingement occurs. It is hypothesized that the repeated abnormal contact leads to damage of the cartilage layer, but could also cause a bone remodelling response according to Wolff's Law. Thus the goal of this study was to assess the relationship between bone metabolic activity measured by PET and BMD measured in CT scans.Five participants with asymptomatic cam deformity, three patients with uni-lateral symptomatic cam FAI and three healthy controls were scanned in a 3T PET-MRI scanner following injection with [18F]NaF. Bone remodelling activity was quantified with Standard Uptake Values (SUVs). SUVmax was analyzed in the antero-superior acetabular rim, femoral head and head-neck junction. In these same regions, BMD was calculated from CT scans using the calibration phantom included in the scan. The relationship between SUVmax and BMD from corresponding regions was assessed using the coefficient of determination (R2) from linear regression.High bone activity was seen in the cam deformity and acetabular rim. SUVmax was negatively correlated with BMD in the antero-superior region of the acetabulum (R2=0.30, p=0.08). SUVmax was positively correlated with BMD in the antero-superior head-neck junction of the femur (R2=0.359, p=0.067). Correlations were weak in other regions.Elevated bone turnover was seen in patients with a cam deformity but the relationship to BMD was moderate. This study demonstrates a pathomechanism of hip degeneration associated with FAI deformities, consistent with Wolff's law and the proposed mechanical cause of hip degeneration in FAI. [18F]-NaF PET SUV may be a biomarker of degeneration, especially in early stages of degeneration, when joint preservation surgery is likely to be the most successful.

The effectiveness of hydrotherapy on return to play in sports following hip arthroscopic surgery: a comparative study.

The postoperative management of femoroacetabular impingement (FAI) is variable with favourable surgical outcomes. Yet there is no evidence on the efficacy of hydrotherapy in athletes undergoing hip arthroscopy for FAI. The purpose of this study was to evaluate the role and the impact of hydrotherapy on return to sports following hip arthroscopy for symptomatic FAI. 2 cohorts of mixed level of athletes from various sports: a hydrotherapy group that followed land-based exercises in combination with hydrotherapy exercises and a control group that followed solely the same land-based exercises. Pre- and postoperative pain and hip-specific outcome scores were completed, and patient satisfaction was rated. A total of 88 hip arthroscopies were included with a minimum of 2 years follow-up; the hydrotherapy group comprised of 36 hips and the control group, 52 hips. There was a significant improvement in time to return to previous performance (HR 1.91, 95% CI, 1.21-3.01; p = 0.005) in the hydrotherapy group compared with the control. The hip-specific scores and patient satisfaction were considerably improved in the hydrotherapy group. The analysis of our data indicates that the incorporation of hydrotherapy into postoperative rehabilitation for hip arthroscopy for FAI accelerates the return of athletes to their pre-injury performance, since recovery time decreased significantly.