Increased Duration and Intensity of Physical Activity Are Associated With Increased Pain in Individuals With Femoroacetabular Impingement Syndrome: An Ecological Momentary Assessment Study.

OBJECTIVE: To investigate the relation between accelerometer-measured physical activity and real-time pain in individuals with femoroacetabular impingement syndrome (FAIS). We tested the hypothesis that increased duration of high intensity activity would contribute to momentary increases in pain. DESIGN: Observational study. SETTING: Participants' natural, day-to-day environment. PARTICIPANTS: Population-based sample of 33 individuals with unilateral FAIS. Important eligibility criteria included no concomitant hip disorders or previous hip surgery. Key sociodemographic features include that all participants were required to have a smartphone. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Duration and intensity of physical activity as measured by a waist-worn accelerometer, and instantaneous pain reported in real-time smartphone-based ecological momentary assessment surveys. Physical activity variables included each person's average sedentary time, light physical activity (LPA), and moderate to vigorous physical activity (MVPA) in the 90 minutes proceeding all pain surveys as well as fluctuation in sedentary, LPA, and MVPA above or below average prior to each individual survey. RESULTS: Linear mixed models revealed that the significant predictors of pain included fluctuation in sedentary time (B=-0.031, P<.001), average LPA (B=0.26, P=.035), and the interaction between fluctuation in LPA and fluctuation in MVPA (B=0.001, P<.001). Fluctuation in sedentary time above a person's average was associated with lower pain, while average LPA and fluctuations above average in both LPA and MVPA were associated with higher pain. CONCLUSIONS: These results suggest that individuals with FAIS can engage in health-enhancing MVPA but should focus on avoiding concurrent increase above average in both high intensity and LPA in the same 90-minute period. Future work is warranted testing the efficacy of such an approach on pain. Additionally, given that high levels of LPA may arise from a host of socioeconomic factors, additional research is needed to disentangle the effect of LPA on pain in FAIS.

UTE T2* cartilage mapping in the hip: a pilot study assessing cartilage in patients with femoroacetabular impingement.

BACKGROUND: UTE T2* cartilage mapping use in patients undergoing femoroacetabular impingement (FAI) has been lacking but may allow the detection of early cartilage damage. PURPOSE: To assess the reproducibility of UTE T2* cartilage mapping and determine the difference in UTE T2* values between FAI and asymptomatic patients and to evaluate the correlation between UTE T2* values and patient-reported symptoms. MATERIAL AND METHODS: Prospective evaluation of both hips (7 FAI and 7 asymptomatic patients). Bilateral hip 3-T MRI scans with UTE T2* cartilage maps were acquired. A second MRI scan was acquired 1-9 months later. Cartilage was segmented into anterosuperior, superior, and posterosuperior regions. Assessment was made of UTE T2* reproducibility (ICC). Mean UTE T2* values in patients were compared (t-tests) and correlation was made with patient-reported outcomes (Spearman's). RESULTS: ICCs of mean UTE T2* were as follows: acetabular, 0.82 (95% CI=0.50-0.95); femoral, 0.76 (95% CI=0.35-0.92). Significant strong correlation was found between mean acetabular UTE T2* values and iHOT12 (ρ = -0.63) and moderate correlation with mHHS (ρ = -0.57). There was no difference in mean UTE T2* values between affected vs. non-affected FAI hips. FAI-affected hips had significantly higher values in acetabulum vs. asymptomatic patients (13.47 vs. 12.55 ms). There was no difference in mean femoral cartilage values between the FAI-affected hips vs. asymptomatic patients. The posterosuperior femoral region had a higher mean value in non-affected FAI hips vs. asymptomatic patients (12.60 vs. 11.53 ms). CONCLUSION: UTE T2* cartilage mapping had excellent reproducibility. Affected FAI hips had higher mean acetabular UTE T2* values than asymptomatic patients. Severity of patient-reported symptoms correlates with UTE T2* acetabular cartilage values.

Prevalence of hip femoroacetabular impingement deformities in high-level (La Liga) male professional football players.

BACKGROUND: Femoroacetabular impingement (FAI) is considered one of the main causes of hip osteoarthritis in young adults, especially in athletes. In recent years, morphological changes in FAI in the hip have been linked to early and intense sports participation, but studying top-level athlete samples is not easy. This paper presents the prevalence of FAI radiological markers in 120 active white male professional football players in the Spanish First Division League (La Liga) and compares the morphological changes with those of a control group of healthy individuals without significant sport activity. METHODS: The precontract medical evaluation hip X-rays of 120 white male professional football players from four different First Division Spanish football teams were prospectively filed and retrospectively reviewed by a dedicated skeletal radiologist. The footballers' hip X-rays were compared with those of a control group of 80 healthy individuals (age-sex matched) without significant sport activity (obtained from routine work medical checks). RESULTS: The femoral head-neck deformity associated with the Cam type of femoroacetabular impingement was observed in 61.6% of professional football players and only in 11.6% of the control group (p <0.01). The presence of "herniation pit" (11.6%) and os acetabuli (13.3%) also reached statistical significance in the professional football players group. In the other analyzed parameters, no statistically significant differences between the groups were observed. CONCLUSIONS: White professional top-level football players have an increased incidence of abnormal lateral epiphyseal extension ("pistol grip deformity"), os acetabuli and herniation pits.

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

OBJECTIVE: 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. MATERIALS AND METHODS: 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. RESULTS: 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). CONCLUSION: 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.

Females and Males Achieve Similar Improvement, Outcomes, and Survivorship Following Hip Arthroscopy with Labral and Capsular Repair for Femoroacetabular Impingement Syndrome at Minimum 10-Year Follow-Up.

PURPOSE: To evaluate the effect of patient sex on 10-year patient-reported outcomes (PROs) and survivorship after hip arthroscopy (HA) for femoroacetabular impingement syndrome (FAIS). METHODS: Patients who underwent primary HA for FAIS with minimum 10-year follow-up from 1/2012-12/2013 were retrospectively reviewed. Female patients were propensity-matched to male patients in a 1:1 ratio by age and body mass index. PROs and rates of minimal clinically important difference (MCID) and patient-acceptable symptom state (PASS) achievement were compared between cohorts. Rate of reoperation-free survivorship was compared between sexes. RESULTS: One-hundred and twenty-one- females (age: 36.2 ± 12.3 years) were matched to 121 males (age: 35.7 ± 11.3 years, p = 0.594) at average follow-up of 10.4 ± 0.4 years. There were no differences in any preoperative demographic characteristics between the groups (p ≥ 0.187). Both groups demonstrated significant improvement in every PRO measure between the preoperative and 10-year postoperative time points (p < 0.001). The magnitude of improvement was similar between the groups for all PRO measures (p ≥ 0.139). At 10-years, female patients trended towards higher MCID achievement for the Hip Outcome Score-Activities of Daily Living subscale (HOS-ADL) than male patients (72.7% vs. 57.3%, p = 0.061), with otherwise similar MCID achievement rates. Females trended towards significantly lower HOS-Sports Subscale PASS achievement (65.4% vs. 77.1%, p = 0.121) with otherwise similar PASS achievement rates between the groups (p ≥ 0.170). CONCLUSION: Female and male patients experienced similar improvement in PROs at ten-year follow-up. MCID and PASS achievement rates were predominantly similar between sexes. Survivorship did not differ between groups. Long-term success can be expected for appropriately indicated patients undergoing HA for FAIS, regardless of sex. LEVEL OF EVIDENCE: III, Retrospective Cohort Study.

Risk factors for prolonged opioid consumption following hip arthroscopy: A secondary analysis of the Femoroacetabular Impingement RandomiSed controlled Trial and embedded cohort study.

PURPOSE: The purpose of the study was to identify prognostic risk factors for prolonged opioid use at 2 and 6 weeks after hip arthroscopy using data from the Femoroacetabular Impingement RandomiSed controlled Trial and its external validation cohort study. METHODS: Opioids were prescribed for postoperative pain management at the surgeon's discretion, with a majority being prescribed a combination of oxycodone and paracetamol (5/325 mg). Prolonged opioid use was defined as the ongoing use of any dosage of opioids reported at either 2 or 6 weeks after surgery to treat femoroacetabular impingement, as recorded in the patient's study medication log. Multivariable logistic regressions were performed to evaluate patient and surgical characteristics, such as preoperative opioid use, type of surgical procedure and intraoperative cartilage state that may be associated with prolonged opioid use at either 2 and 6 weeks postoperatively. RESULTS: A total of 265 and 231 patients were included for analysis at 2 and 6 weeks postoperatively, respectively. The median age of participants was 35 years (interquartile range [IQR]: 27-42) and 33% were female. At 2 weeks postoperatively, female sex (odds ratio [OR]: 2.56; 95% confidence interval: [CI] 1.34-4.98, p = 0.005), higher body mass index (BMI) (OR: 1.10; 95% CI: 1.02-1.18, p = 0.009), active tobacco use (OR: 4.06; 95% CI: 1.90-8.97, p < 0.001), preoperative opioid use (OR: 10.1; 95% CI: 3.25-39.1, p < 0.001) and an Outerbridge classification of ≥3 (OR: 2.33; 95% CI: 1.25-4.43, p = 0.009) were significantly associated with prolonged opioid use. At 6 weeks postoperatively, only preoperative opioid use was significantly associated with prolonged opioid consumption (OR: 10.6; 95% CI: 3.60-32.6, p < 0.001). CONCLUSION: Preoperative opioid use was significantly associated with continued opioid use at 2 and 6 weeks postoperatively. Specific patient factors including female sex, higher BMI, active tobacco use and more severe cartilage damage should be considered in developing targeted strategies to limit opioid use after surgery. LEVEL OF EVIDENCE: Level III.

Increased combined anteversion is associated with larger posterior acetabular rim ossification in patients with femoroacetabular impingement syndrome.

PURPOSE: (1) To determine the prevalence, magnitude and distribution pattern of acetabular rim ossification in patients with femoroacetabular impingement syndrome (FAIS) and (2) to determine the association between acetabular rim ossification and rotational abnormalities of the hip. METHODS: Patients underwent hip arthroscopic surgery for FAIS at our institute between January 2021 and May 2022 were retrospectively reviewed. Patients were included if preoperative computed tomography (CT) images of the operated hip and ipsilateral distal femur were available for the measurement of femoral and acetabular anteversion. The presence and size of acetabular rim ossification were evaluated on coronal CT sections for the superior half of the acetabulum on each clockface location. The associations between acetabular rim ossification and radiographic parameters of hip rotational morphology were examined. RESULTS: A total of 214 hips were included. Acetabular rim ossification was found in 167 hips (78%) and the most common locations were 10 and 11 o'clock. Patients presenting with acetabular rim ossification had a mean size of 4.6 ± 1.6 mm. It was the largest at 9 o'clock position (4.9 ± 2.2 mm), with a decreasing trend in size from posterior to anterior. Logistics regression analysis found age was associated with the occurrence of posterior ossification (p = 0.002). Linear regression analysis found age (p = 0.049) and male sex (p < 0.001) were significantly correlated with the size of ossification. Patients with increased cranial combined anteversion had larger posterior ossification than patients with normal and decreased cranial combined anteversion (4.2 ± 2.9 vs. 3.1 ± 2.5 mm, p = 0.016; 4.2 ± 2.9 vs. 2.5 ± 2.4 mm, p = 0.005). CONCLUSION: Increased combined anteversion is associated with greater posterior acetabular rim ossification. The presence and size of acetabular rim ossification are positively associated with older age and male sex. LEVEL OF EVIDENCE: Level III.

Current concepts in the diagnosis and management of Os Acetabuli.

PURPOSE: The aim of this review is to appraise the current evidence on the epidemiology, pathophysiology, diagnosis and management of os acetabuli. METHODS: A scoping review was conducted according to the Joanna Briggs Institute guidelines. A systematic search was performed on Medline (PubMed), Embase and Cochrane Library. Inclusion criteria comprised observational and interventional studies and review articles published in the English language that focused on patients with os acetabuli according to the PRISMA extension of scoping reviews checklist using the terms 'Os Acetabuli' or 'os acetabula' or 'acetabular ossicles'. A narrative synthesis of results was undertaken, and the included articles were divided into (i) definition, (ii) aetiology, (iii) diagnosis and imaging and (iv) management of os acetabuli. RESULTS: 107 articles were screened, with 22 meeting the eligibility criteria. A total of 8836 patients were considered, of which 604 had os acetabuli. The mean age was 32.8 years. The prevalence of os acetabuli ranged from 3.4 to 7.7%, with a higher prevalence in males compared to females. True os acetabuli was defined as an unfused secondary ossification centre along the acetabular rim. The aetiology of os acetabuli is thought to be secondary to acetabular dysplasia and/or femoroacetabular impingement. Standard of care for management of symptomatic os acetabuli is considered to be arthroscopic excision unless the excision results in acetabular undercoverage and/or instability, in which case, fixation is recommended. CONCLUSIONS: Successful management of os acetabuli depends on understanding the pathology and treating the underlying cause rather than treating the os acetabuli in isolation. Future work needs to focus on establishing clear diagnostic criteria, consensus on definition and an evidence-based treatment algorithm.

Worker's compensation and no-fault insurance are associated with decreased patient reported outcomes and higher rates of revision at 2 and 5 years follow-up compared to patients with commercial insurance undergoing hip arthroscopy for femoroacetabular impingement.

PURPOSE: To investigate the patient reported outcomes (PROs) of patients undergoing hip arthroscopy (HA) for femeroacetabular impingement syndrome (FAIS), a condition where irregular bone growth in the hip joint leads to friction and pain during movement, who have worker's compensation (WC) or no-fault insurance (NF) versus commercial insurance (CI) at both 2 year and 5 year follow-up. METHODS: This was a single center, single surgeon, retrospective analysis performed between August 2007 and May 2023 of consecutive patients that underwent HA, a minimally invasive surgical procedure used to diagnose and treat problems inside the hip joint through small incisions, for FAIS. Patients were divided into two cohorts-those with WC/NF and those with commercial insurance (CI). Patient reported outcomes (PROs), which included modified Harris Hip Score (mHHS) and Non-Arthritic Hip Score (NAHS), were collected preoperatively, as well as at least 2-year postoperatively. Additionally, other clinically relevant outcomes variables including prevalence of revision surgery and conversion to total hip arthroplasty were recorded. RESULTS: Three hundred and forty three patients met inclusion criteria. There were 32 patients in the WC/NF cohort and 311 patients in the commercial cohort. When controlling for age, sex, and Body Mass Index (BMI), WC/NF status was associated with lower mHHS at both 2 year (ß = - 8.190, p < 0.01, R2 = 0.092) and 5 year follow-up (ß = - 16.60, p < 0.01, R2 = 0.179) and NAHS at 5 year follow up (ß = - 13.462, p = 0.03, R2 = 0.148). The WC/NF cohort had a lower rate of achieving Substantial Clinical Benefit (SCB) for mHHS at 2-years follow-up (66.7% vs. 84.1%, p = 0.02).The rate of revision hip arthroscopy was significantly higher in the worker's compensation/no fault cohort than the commercial insurance cohort (15.6% vs. 3.5%, p < 0.01). The rate of conversion to total hip arthroplasty (THA) in the WC/NF cohort was not significantly different than the rate of conversion to THA in the commercial insurance cohort (0.0% vs. 3.2%, p = 0.30). CONCLUSION: Patients with WC/NF insurance may expect a significant improvement from baseline mHHS and NAHS following HA for FAIS at short-term follow-up. However, this improvement may not be as durable as those experienced by patients with CI. Additionally, WC/NF patients should be counseled that they have a higher risk of undergoing revision hip arthroscopy than similar CI patients. LEVEL OF EVIDENCE: III, Retrospective Comparative Prognostic Investigation.

Comparison Between Movement Pattern Training and Strengthening on Kinematics and Kinetics in Patients With Chronic Hip-Related Groin Pain.

The purpose of this study was to compare the preliminary effects of movement pattern training (MoveTrain) versus strengthening/flexibility (standard) treatment on hip and pelvic biomechanics in patients with chronic hip-related groin pain. This is a secondary analysis of data collected during a pilot randomized clinical trial. Thirty patients with hip pain, between the ages of 15 and 40 years, were randomized to MoveTrain or standard. Both groups completed 10 treatment sessions over 12 weeks along with a daily home exercise program. Three-dimensional motion analysis was used to collect kinematic and kinetic data of the pelvis and hip during a single-leg squat task at pretreatment and immediately posttreatment. Compared with the standard group, the MoveTrain group demonstrated smaller hip adduction angles (P = .006) and smaller hip external adduction moments (P = .008) at posttreatment. The desired changes to hip joint biomechanics, as found in this study, may require specificity in training that could allow health care professionals to better customize the rehabilitation of patients with hip pain. These findings can also be applied to the design and implementation of future clinical trials to strengthen our understanding of the long-term implications of different rehabilitation techniques for patients with hip pain.

Hip arthroscopy with initial access to the peripheral compartment for femoroacetabular impingement: midterm results from a large-scale patient cohort.

BACKGROUND: Hip arthroscopy with initial access to the peripheral compartment could reduce the risk of iatrogenic injury to the labrum and cartilage; furthermore, it avoids the need for large capsulotomies with separate portals for peripheral and central (intra-articular) arthroscopy. Clinical results of the peripheral-compartment-first technique remain sparse, in contrast to those of conventional hip arthroscopy starting in the intra-articular central compartment. The purpose of this study was to assess outcome of hip arthroscopy with the peripheral-compartment-first technique, including complication rates, revision rates and patient-reported outcome scores. MATERIALS AND METHODS: This outcome study included 704 hips with femoroacetabular impingement. All arthroscopies were performed using the peripheral-compartment-first technique. A joint replacement registry and the institutional database were used to assess the revision and complication rates, while patient-reported outcome measures were used to assess functional outcomes and patient satisfaction. RESULTS: In total, 704 hips (615 patients) were followed up for a mean of 6.2 years (range 1 to 9 years). The mean age of the patients was 32.1 ± 9.2 years. During the follow-up period, 26 of 704 (3.7%) hips underwent total hip arthroplasty (THA) after a mean of 1.8 ± 1.2 years, and 18 of the 704 (2.6%) hips required revision hip arthroscopy after a mean of 1.2 ± 2.1 years. 9.8% of the hips had an unsatisfactory patient-reported outcome at final follow-up. CONCLUSIONS: The results for the peripheral-compartment-first technique were promising. We recommend a well-conducted randomized controlled clinical trial to guide future therapeutic recommendations regarding the most favorable hip arthroscopy technique. LEVEL OF EVIDENCE: Level IV, therapeutic study. TRIAL REGISTRATION: This study was registered at ClinicalTrials.gov (U.S. National Library of Medicine; ID: NCT05310240).

Does femoroacetabular impingement syndrome affect range of motion? A systematic review with meta-analysis.

BACKGROUND: It is unclear whether femoroacetabular impingement syndrome (FAIS) affect hip range of motion (ROM). SOURCES OF DATA: We performed a systematic review with meta-analysis searching six electronic databases from inception to March 21, 2022. We included studies assessing hip ROM in FAIS, FAI morphology without symptoms (FAIm), and healthy controls. Mean differences between groups were measured in ROM degrees with 95% confidence interval (CI). AREAS OF AGREEMENT: A total of 17 studies (1702 hips) were included. Comparison of FAIS patients versus healthy controls showed that hip ROM was clinically and statistically reduced in FAIS for internal rotation (90° hip flexion, -8.01°, 95% CI: -11.21, -4.90; 0° hip flexion -6.38°, 95% CI: -9.79, -2.97); adduction (90° hip flexion, -4.74°, 95% CI: -8.13, -1.34); flexion (-5.41°, 95% CI: -7.05, -3.49), abduction (0° hip flexion, -5.76°, 95% CI: -8.38, -3.23), and external rotation (90° hip flexion, -3.5°, 95% CI: -5.32, -1.67) ranging from low to high certainty of evidence. Comparison of FAIm versus healthy controls showed no statistically significant differences in any direction of movement, albeit with uncertainty of evidence. AREAS OF CONTROVERSY: The certainty of evidence was unclear, particularly for asymptomatic FAIm. GROWING POINTS: Hip ROM may be reduced in all directions except extension in FAIS compared to controls. Hip ROM may not be restricted in asymptomatic FAIm. AREAS TIMELY FOR DEVELOPING RESEARCH: Further studies are needed to resolve the uncertainty of evidence about ROM restrictions in asymptomatic FAIm compared to healthy controls.

Hip Labral Morphological Changes in Patients with Femoroacetabular Impingement Speed Up the Onset of Early Osteoarthritis.

Over the last decade, evidence has mounted for a prominent etiologic role of femoroacetabular impingement (FAI) in the development of early hip osteoarthritis (OA). The aim of this study was to compare the ultrastructure and tissue composition of the hip labrum in healthy and pathological conditions, as FAI and OA, to provide understanding of structural changes which might be helpful in the future to design targeted therapies and improve treatment indications. We analyzed labral tissue samples from five healthy multi-organ donors (MCDs) (median age, 38 years), five FAI patients (median age, 37 years) and five late-stage OA patients undergoing total hip replacement (median age, 56 years). We evaluated morpho-functional by histology and transmission electron microscopy. Extracellular matrix (ECM) structure changes were similar in specimens from FAI compared to those from patients with OA (more severe in the latter) showing disorganization of collagen fibers and increased proteoglycan content. In FAI and in OA nuclei the chromatin was condensed, organelle degenerated and cytoplasm vacuolized. Areas of calcification were mainly observed in FAI and OA labrum, as well as apoptotic-like features. We showed that labral tissue of patients with FAI had similar pathological alterations of tissue obtained from OA patients, suggesting that FAI patients might have high susceptibility to develop OA.

MRI texture analysis of acetabular cancellous bone can discriminate between normal, cam positive, and cam-FAI hips.

OBJECTIVES: To compare the MRI texture profile of acetabular subchondral bone in normal, asymptomatic cam positive, and symptomatic cam-FAI hips and determine the accuracy of a machine learning model for discriminating between the three hip classes. METHODS: A case-control, retrospective study was performed including 68 subjects (19 normal, 26 asymptomatic cam, 23 symptomatic cam-FAI). Acetabular subchondral bone of unilateral hip was contoured on 1.5 T MR images. Nine first-order 3D histogram and 16 s-order texture features were evaluated using specialized texture analysis software. Between-group differences were assessed using Kruskal-Wallis and Mann-Whitney U tests, and differences in proportions compared using chi-square and Fisher's exact tests. Gradient-boosted ensemble methods of decision trees were created and trained to discriminate between the three groups of hips, with percent accuracy calculated. RESULTS: Sixty-eight subjects (median age 32 (28-40), 60 male) were evaluated. Significant differences among all three groups were identified with first-order (4 features, all p ≤ 0.002) and second-order (11 features, all p ≤ 0.002) texture analyses. First-order texture analysis could differentiate between control and cam positive hip groups (4 features, all p ≤ 0.002). Second-order texture analysis could additionally differentiate between asymptomatic cam and symptomatic cam-FAI groups (10 features, all p ≤ 0.02). Machine learning models demonstrated high classification accuracy of 79% (SD 16) for discriminating among all three groups. CONCLUSION: Normal, asymptomatic cam positive, and cam-FAI hips can be discriminated based on their MRI texture profile of subchondral bone using descriptive statistics and machine learning algorithms. CLINICAL RELEVANCE STATEMENT: Texture analysis can be performed on routine MR images of the hip and used to identify early changes in bone architecture, differentiating morphologically abnormal from normal hips, prior to onset of symptoms. KEY POINTS: • MRI texture analysis is a technique for extracting quantitative data from routine MRI images. • MRI texture analysis demonstrates that there are different bone profiles between normal hips and those with femoroacetabular impingement. • Machine learning models can be used in conjunction with MRI texture analysis to accurately differentiate between normal hips and those with femoroacetabular impingement.

Relationships between self-perceived and clinical expression of pain and function differ based on the underlying pathology of the human hip.

BACKGROUND: Patient-reported outcomes are commonly used to assess patient symptoms. The effect of specific hip pathology on relationships between perceived and objectively measured symptoms remains unclear. The purpose of this study was to evaluate differences of function and pain in patients with FAIS and DDH, to assess the correlation between perceived and objective function, and to determine the influence of pain on measures of function. METHODS: This prospective cross-sectional study included 35 pre-operative patients (60% female) with femoroacetabular impingement syndrome (FAIS) and 37 pre-operative patients (92% female) with developmental dysplasia of the hip (DDH). Objectively measured function (6-min walk [6MWT], single leg hop [SLHT], Biodex sway [BST], hip abduction strength [HABST], and STAR excursion balance reach [STAR] tests), patient-reported function (UCLA Activity, Hip Outcome Score [HOS], Short Form 12 [SF-12], and Hip Disability and Osteoarthritis Outcome Score [HOOS]), and patient-reported pain (HOOS Pain, visual analogue scale (VAS), and a pain location scale) were collected during a pre-surgical clinic visit. Between-group comparisons of patient scores were performed using Wilcoxon Rank-Sum tests. Within-group correlations were analyzed using Spearman's rank correlation coefficients. Statistical correlation strength was defined as low (r = ± 0.1-0.3), moderate (r = ± 0.3-0.5) and strong (r > ± 0.5). RESULTS: Patients with DDH reported greater pain and lower function compared to patients with FAIS. 6MWT distance was moderately-to-strongly correlated with a number of patient-reported measures of function (FAIS: r = 0.37 to 0.62, DDH: r = 0.36 to 0.55). Additionally, in patients with DDH, SLHT distance was well correlated with patient reported function (r = 0.37 to 0.60). Correlations between patient-reported pain and objectively measured function were sparse in both patient groups. In patients with FAIS, only 6MWT distance and HOOS Pain (r = -0.53) were significantly correlated. In patients with DDH, 6MWT distance was significantly correlated with VAS Average (r = -0.52) and Best (r = -0.53) pain. CONCLUSION: Pain is greater and function is lower in patients with DDH compared to patients with FAIS. Moreover, the relationship between pain and function differs between patient groups. Understanding these differences is valuable for informing treatment decisions. We recommend these insights be incorporated within the clinical continuum of care, particularly during evaluation and selection of surgical and therapeutic interventions.

Dynamic ultrasound assessment of hip instability and anterior and posterior hip impingement.

OBJECTIVE: In this technical report, we describe our protocol for the dynamic sonographic evaluation of the hip and assess reliability of the ultrasound assessment of hip microinstability. MATERIALS AND METHODS: Our clinical experience with a standardized dynamic ultrasound of the hip performed in a series of 27 patients with imaging performed by an experienced musculoskeletal radiologist during physical examination by an orthopedic surgeon specializing in hip preservation is illustrated with clinical photographs and ultrasound images from volunteers and selected patients. Interrater reliability for the diagnosis of microinstability was calculated. RESULTS: Dynamic ultrasound technique and findings of hip instability, femoroacetabular impingement, and ischiofemoral impingement with corresponding clinical photos showing the necessary physical examination maneuvers are described. Interrater agreement for the diagnosis of microinstability was substantial (κ 0.606 [0.221-0.991]). CONCLUSION: At our institution, dynamic ultrasound of the hip during physical examination complements information gathered from static imaging by providing real-time correlation of symptoms with what is occurring anatomically.

Feasibility of photon-counting CT for femoroacetabular impingement syndrome evaluation: lower radiation dose and improved diagnostic confidence.

OBJECTIVE: The feasibility of low-dose photon-counting detector (PCD) CT to measure alpha and acetabular version angles of femoroacetabular impingement (FAI). MATERIAL AND METHODS: FAI patients undergoing an energy-integrating detector (EID) CT underwent an IRB-approved prospective ultra-high-resolution (UHR) PCD-CT between 5/2021 and 12/2021. PCD-CT was dose-matched to the EID-CT or acquired at 50% dose. Simulated 50% dose EID-CT images were generated. Two radiologists evaluated randomized EID-CT and PCD-CT images and measured alpha and acetabular version angles on axial image slices. Image quality (noise, artifacts, and visualization of cortex) and confidence in non-FAI pathology were rated on a 4-point scale (3 = adequate). Preference tests of standard dose PCD-CT, 50% dose PCD-CT, and 50% dose EID-CT relative to standard dose EID-CT were performed using Wilcoxon Rank test. RESULTS: 20 patients underwent standard dose EID-CT (~ CTDIvol, 4.5 mGy); 10 patients, standard dose PCD-CT (4.0 mGy); 10 patients, 50% PCD-CT (2.6 mGy). Standard dose EID-CT images were scored as adequate for diagnostic task in all categories (range 2.8-3.0). Standard dose PCD-CT images scored higher than the reference in all categories (range 3.5-4, p < 0.0033). Half-dose PCD-CT images also scored higher for noise and cortex visualization (p < 0.0033) and equivalent for artifacts and visualization of non-FAI pathology. Finally, simulated 50% EID-CT images scored lower in all categories (range 1.8-2.4, p < 0.0033). CONCLUSIONS: Dose-matched PCD-CT is superior to EID-CT for alpha angle and acetabular version measurement in the work up of FAI. UHR-PCD-CT enables 50% radiation dose reduction compared to EID while remaining adequate for the imaging task.

The diagnosis of hip microinstability is correlated with ease of intra-operative hip distraction.

PURPOSE: Hip microinstability has emerged as a contributor to young adult, non-arthritic hip pain. There is a paucity of objective clinical data to identify patients with hip microinstability and guide surgical treatment. The purpose of this study was to identify the degree of distractibility in patients with and without microinstability undergoing hip arthroscopy. METHODS: A single-surgeon series of hip arthroscopies were retrospectively reviewed from 2014-2020. All procedures were performed with paralysis on a fracture table with a perineal post where 1 turn of fine traction equates to 4 mm of axial traction. Diagnosis was recorded as isolated instability, instability plus femoroacetabular impingement (FAI), and isolated FAI. Operative reports were reviewed to collect patient demographic data, number of turns of traction required for adequate distraction of the femoral head relative to the acetabulum (10 mm), and the presence of residual subluxation after initial traction was released. RESULTS: A total of 464 patients were identified, 26 (5.6%) with isolated microinstability, 183 (39.4%) with microinstability with FAI anatomy, and 255 (55.0%) with FAI. The concurrent diagnosis of microinstability was associated with decreased turns required to adequately distract the hip. Isolated microinstability patients required 6.9 turns (IQR 4.6-8.8) while those with instability plus FAI required 8.8 turns (IQR 6.5-11) and isolated FAI required 19.1 turns (IQR 15-22). Residual subluxation after removal of negative intra-articular pressure but before performing the hip arthroscopy was more commonly associated with instability, occurring in 84.6% of isolated instability and 86.9% of instability plus FAI as compared with 29.8% in the isolated FAI cohort. CONCLUSION: A diagnosis of hip microinstability, with or without features of FAI, is associated with decreased axial traction required to distract the hip. These data support the use of intra-operative ease of distraction as a method of identifying patients with hip microinstability. LEVEL OF EVIDENCE: Level III.

High survivorship and excellent 5-year outcomes in patients older than 40 years undergoing arthroscopy for femoroacetabular impingement.

PURPOSE: To assess 5-year clinical outcome, in adults > 40 years of age, following hip arthroscopy for femoroacetabular impingement compared to a younger, matched, control group. METHODS: All primary arthroscopies for FAI between 2009 and 2016 were considered (n = 1762). Hips presenting with Tönnis > 1, lateral centre edge angle < 25°, or prior hip surgery were excluded. Younger (< 40 years) and older hips (> 40 years) were matched for gender, Tönnis grade, capsular repair and radiological parameters. Survival (avoidance of total hip replacement {THR}) was compared between the groups. Patient reported outcome measures (PROMs) were also completed at baseline and 5 years to assess changes in functional capacity. Additionally, hip range of motion (ROM) was assessed at baseline and review. The minimal clinically important difference (MCID) was determined and compared between groups. RESULTS: Ninety-seven older hips were matched to 97 younger controls (78% male in both groups). The average age of the older group at the time of surgery was 48.0 ± 5.7 years, compared to 26.7 ± 6.0. Six (6.2%) of the older hips and 1 (1%) of younger hips converted to THR (p = 0.043, effect size = 0.74, large). There were statistically significant improvements in all PROMs. At follow-up, there were no differences in PROMs between groups; significant improvements in hip ROM were also observed with no difference in ROM between groups at either time point. Similar achievement of MCIDs was observed in both groups. CONCLUSIONS: Older patients experience a high survivorship rate at 5 years, although this may be lower than younger patients. Where THR is avoided, large clinically significant improvements in pain and function are observed. LEVEL OF EVIDENCE: Level IV.

Hip arthroscopy for femoroacetabular impingement is associated with significant improvement in early patient reported outcomes: analysis of 4963 cases from the UK non-arthroplasty registry (NAHR) dataset.

PURPOSE: Results from recent randomised controlled trials demonstrate the superiority of surgery over physiotherapy in patients with femoroacetabular impingement (FAI) of the hip in early follow-up. However, there is paucity of evidence regarding which factors influence outcomes of FAI surgery, particularly notable is the lack of information on the effect of impingement subtype (cam or pincer or mixed) on patient reported outcomes measures (PROMs). This study aims to evaluate the early outcomes of hip arthroscopy for FAI, and their determinants. METHODS: This is a retrospective analysis of prospectively collected data from the UK Non-Arthroplasty Hip Registry (NAHR) of patients undergoing arthroscopic intervention for FAI between 2012 and 2019. The null hypothesis was that there is no difference in PROMs, based on morphological subtype of FAI treated or patient characteristics, at each follow-up timepoint. The outcome measures used for the study were the iHOT-12 score and the EQ5D Index and VAS 6- and 12-month follow-up. RESULTS: A cohort of 4963 patients who underwent arthroscopic treatment of FAI were identified on the NAHR database. For all FAI pathology groups, there was significant improvement from pre-operative PROMs when compared to those at 6 and 12 months. Overall, two-thirds of patients achieved the minimum clinically important difference (MCID), and almost half achieved substantial clinical benefit (SCB) for iHOT-12 by 12 months. Pre-operatively, and at 12-month follow-up, iHOT-12 scores were significantly poorer in the pincer group compared to the cam and mixed pathology groups (p < 0.01). Multivariable analysis revealed PROMS improvement in the setting of a higher-grade cartilage lesion. CONCLUSION: This registry study demonstrates that hip arthroscopy is an effective surgical treatment for patients with symptomatic FAI and results in a statistically significant improvement in PROMs which are maintained through 12 months follow-up. LEVEL OF EVIDENCE: III.