Standardised measurement of physical capacity in young and middle-aged active adults with hip-related pain: recommendations from the first International Hip-related Pain Research Network (IHiPRN) meeting, Zurich, 2018.

Hip-related pain can significantly impact quality of life, function, work capacity, physical activity and family life. Standardised measurement methods of physical capacity of relevance to young and middle-aged active adults with hip-related pain are currently not established. The aim of this consensus paper was to provide recommendations for clinical practice and research on standardised measurement methods of physical capacity in young and middle-aged active adults with hip-related pain. Four areas of importance were identified: (1) clinical measures (range of motion, muscle strength, functional impairments), (2) laboratory-based measures (biomechanics and muscle function (muscle activity, size and adiposity)), (3) physical activity, and (4) return to sport/performance. The literature was reviewed, and a summary circulated to the working group to inform discussion at the consensus meeting. The working group developed clinical and research recommendations from the literature review, which were further discussed and modified within the working group at the consensus meeting. These recommendations were then presented to all 38 International Hip-related Pain Research Network (IHiPRN) participants for further discussion, refinement and consensus voting. Therefore, the recommendations voted on were based on a combination of current evidence and expert opinion. The consensus meeting voted on 13 recommendations, six of which were clinically orientated, and seven more research specific. We recommended that clinicians working with young and middle-aged active adults with hip-related pain assess strength using objective methods of measurement, and clinically assess performance of functional tasks, including walking and running. Physical activity should be quantified using both self-reported and objective measures, and patient expectations of recovery should be quantified prior to treatment. It was recommended that return to physical activity (including sport and occupation) be quantified, and sport-specific activities should be assessed prior to return to sport. The IHiPRN participants were uncertain regarding recommendations for range of motion assessment. Research recommendations were that the measurement properties of range of motion, strength and functional performance tests be investigated, reported and improved in both clinical and research settings. Reporting of movement-related parameters (biomechanics and muscle function) should be standardised and the relationship among movement-related parameters, symptoms, function, quality of life, and intra-articular and imaging findings should be investigated. Quantification of return to physical activity (including sport and occupational demands) is required in future research, and the return to sport continuum should be used. Future research is required to determine the best criteria for rehabilitation progression and return to physical activity following hip-related pain management.

Patient-reported outcome measures for hip-related pain: a review of the available evidence and a consensus statement from the International Hip-related Pain Research Network, Zurich 2018.

Hip-related pain is a well-recognised complaint among active young and middle-aged active adults. People experiencing hip-related disorders commonly report pain and reduced functional capacity, including difficulties in executing activities of daily living. Patient-reported outcome measures (PROMs) are essential to accurately examine and compare the effects of different treatments on disability in those with hip pain. In November 2018, 38 researchers and clinicians working in the field of hip-related pain met in Zurich, Switzerland for the first International Hip-related Pain Research Network meeting. Prior to the meeting, evidence summaries were developed relating to four prioritised themes. This paper discusses the available evidence and consensus process from which recommendations were made regarding the appropriate use of PROMs to assess disability in young and middle-aged active adults with hip-related pain. Our process to gain consensus had five steps: (1) systematic review of systematic reviews; (2) preliminary discussion within the working group; (3) update of the more recent high-quality systematic review and examination of the psychometric properties of PROMs according to established guidelines; (4) formulation of the recommendations considering the limitations of the PROMs derived from the examination of their quality; and (5) voting and consensus. Out of 102 articles retrieved, 6 systematic reviews were selected and assessed for quality according to AMSTAR 2 (A MeaSurement Tool to Assess systematic Reviews). Two showed moderate quality. We then updated the most recent review. The updated literature search resulted in 10 additional studies that were included in the qualitative synthesis. The recommendations based on evidence summary and PROMs limitations were presented at the consensus meeting. The group makes the following recommendations: (1) the Hip and Groin Outcome Score (HAGOS) and the International Hip Outcome Tool (iHOT) instruments (long and reduced versions) are the most appropriate PROMs to use in young and middle-aged active adults with hip-related pain; (2) more research is needed into the utility of the HAGOS and the iHOT instruments in a non-surgical treatment context; and (3) generic quality of life measures such as the EuroQoL-5 Dimension Questionnaire and the Short Form Health Survey-36 may add value for researchers and clinicians in this field. We conclude that as none of the instruments shows acceptable quality across various psychometric properties, more methods studies are needed to further evaluate the validity of these PROMS-the HAGOS and iHOT-as well as the other (currently not recommended) PROMS.

Consensus recommendations on the classification, definition and diagnostic criteria of hip-related pain in young and middle-aged active adults from the International Hip-related Pain Research Network, Zurich 2018.

There is no agreement on how to classify, define or diagnose hip-related pain-a common cause of hip and groin pain in young and middle-aged active adults. This complicates the work of clinicians and researchers. The International Hip-related Pain Research Network consensus group met in November 2018 in Zurich aiming to make recommendations on how to classify, define and diagnose hip disease in young and middle-aged active adults with hip-related pain as the main symptom. Prior to the meeting we performed a scoping review of electronic databases in June 2018 to determine the definition, epidemiology and diagnosis of hip conditions in young and middle-aged active adults presenting with hip-related pain. We developed and presented evidence-based statements for these to a panel of 37 experts for discussion and consensus agreement. Both non-musculoskeletal and serious hip pathological conditions (eg, tumours, infections, stress fractures, slipped capital femoral epiphysis), as well as competing musculoskeletal conditions (eg, lumbar spine) should be excluded when diagnosing hip-related pain in young and middle-aged active adults. The most common hip conditions in young and middle-aged active adults presenting with hip-related pain are: (1) femoroacetabular impingement (FAI) syndrome, (2) acetabular dysplasia and/or hip instability and (3) other conditions without a distinct osseous morphology (labral, chondral and/or ligamentum teres conditions), and that these terms are used in research and clinical practice. Clinical examination and diagnostic imaging have limited diagnostic utility; a comprehensive approach is therefore essential. A negative flexion-adduction-internal rotation test helps rule out hip-related pain although its clinical utility is limited. Anteroposterior pelvis and lateral femoral head-neck radiographs are the initial diagnostic imaging of choice-advanced imaging should be performed only when requiring additional detail of bony or soft-tissue morphology (eg, for definitive diagnosis, research setting or when planning surgery). We recommend clear, detailed and consistent methodology of bony morphology outcome measures (definition, measurement and statistical reporting) in research. Future research on conditions with hip-related pain as the main symptom should include high-quality prospective studies on aetiology and prognosis. The most common hip conditions in active adults presenting with hip-related pain are: (1) FAI syndrome, (2) acetabular dysplasia and/or hip instability and (3) other conditions without distinct osseous morphology including labral, chondral and/or ligamentum teres conditions. The last category should not be confused with the incidental imaging findings of labral, chondral and/or ligamentum teres pathology in asymptomatic people. Future research should refine our current recommendations by determining the clinical utility of clinical examination and diagnostic imaging in prospective studies.

Physiotherapist-led treatment for young to middle-aged active adults with hip-related pain: consensus recommendations from the International Hip-related Pain Research Network, Zurich 2018.

The 1st International Hip-related Pain Research Network meeting discussed four prioritised themes concerning hip-related pain in young to middle-aged adults: (1) diagnosis and classification of hip-related pain; (2) patient-reported outcome measures for hip-related pain; (3) measurement of physical capacity for hip-related pain; (4) physiotherapist-led treatment for hip-related pain. Thirty-eight expert researchers and clinicians working in the field of hip-related pain attended the meeting. This manuscript relates to the theme of physiotherapist-led treatments for hip-related pain. A systematic review on the efficacy of physiotherapist-led interventions for hip-related pain (published separately) was conducted and found that strong evidence for physiotherapist-led treatments was lacking. Prior to the meeting, draft consensus recommendations for consideration in the meeting were also developed based on the systematic review. The draft consensus recommendations were presented to all of the meeting participants via email, at least 1 week prior to the meeting. At the meeting, these recommendations were discussed, revised and voted on. Six recommendations for clinical practice and five recommendations for research were included and all gained consensus. Recommendations for clinical practice were that (i) Exercise-based treatments are recommended for people with hip-related pain. (ii) Exercise-based treatment should be at least 3 months duration. (iii) Physiotherapist-led rehabilitation after hip surgery should be undertaken. (iv) Patient-reported outcome measures, measures of physical impairment and measures of psychosocial factors should be used to monitor response to treatment. (v) Physical activity (that may include sport) is recommended for people with hip-related pain. (vi) Clinicians should discuss patient expectations, use shared-decision making and provide education. Recommendations for research were (i) Reporting of exercise programmes: Exercise descriptors such as load magnitude, number of repetitions and sets, duration of whole programme, duration of contractile element of exercise, duration of one repetition, time under tension, rest between repetitions, range of motion through which the exercise is performed, and rest between exercise sessions should be reported. (ii) Research should investigate the optimal frequency, intensity, time, type, volume and progression of exercise therapy. (iii) Research should examine the effect of patient education in people with hip-related pain. (iv) Research should investigate the effect of other treatments used in people with hip-related pain (for example: manual therapy, medications, injections). (v) Research should examine the impact of comorbidities and social determinants on treatment effectiveness in people with hip-related pain. Clinicians and researchers working with young to middle-aged active adults with hip-related pain may use these consensus recommendations to guide, develop, test and implement individualised, evidence-based physiotherapist-led rehabilitation programmes.

Editorial Commentary: Return to Sport: An Ill-Defined Parameter.

Femoroacetabular impingement syndrome (FAIS) is a common cause of hip pain and dysfunction in athletes, which can impair their ability to perform and compete in sports. Hip arthroscopy has become a popular and successful treatment option for the management of FAIS and the return to sport (RTS) of athletes. The concept of RTS has evolved in the last years. Various different factors need to be considered when evaluating RTS after hip arthroscopy for FAIS, such as (1) the definition of RTS (return to participation, RTS, return to performance), (2) the sport type (high-impact vs low-impact) and sport level (professional vs recreational), and (3) the time to follow-up evaluation. In addition, return to high-impact sports, such as soccer, might not be the best recommendation for some patients undergoing hip arthroscopy for FAIS, as it may accelerate the degeneration of the hip joint. Future research should consider all these aspects of the RTS outcome after hip arthroscopy for FAIS. Valid RTS rates are of utmost importance to provide adequate expectations to patients and to guide decision-making of hip surgeons.

Effectiveness of multicomponent lower extremity injury prevention programmes in team-sport athletes: an umbrella review.

OBJECTIVE: To identify which exercise combinations are most effective as part of a lower extremity injury prevention programme for team-sport athletes. DESIGN: Umbrella review. DATA SOURCES: A comprehensive literature search was performed in PubMed, Scopus, Cochrane Library and PEDro databases. Studies published between January 2000 and March 2017 were included in this umbrella review. STUDY ELIGIBILITY CRITERIA: Moderate to high-quality systematic reviews that investigated the effectiveness of a combination of two or more exercise components, that is, strength, agility, plyometrics, balance, stretching, technique, warm-up and functional activity, regarding injury incidence/rate of lower extremity injuries in team-sport athletes. The methodological quality of the included systematic reviews was independently assessed by two reviewers using the Assessing the Methodological Quality of Systematic Reviews measurement tool and the Grading of Recommendations Assessment, Development and Evaluation guidelines were used to assess the overall quality of evidence for particular outcomes. RESULTS: Twenty-four systematic reviews met the inclusion criteria. Multicomponent exercise interventions were effective in reducing the injury incidence/rate of lower extremity, knee, ACL and ankle injuries, but not groin injuries. Strength and balance exercise components were included in 10 of 11 effective injury prevention programmes for the lower extremity, knee, ACL and ankle injuries. SUMMARY/CONCLUSION: Lower extremity injury prevention programmes in team sports are effective in preventing lower extremity, knee, ACL and ankle injuries. Lower extremity muscle strength and balance exercises should be prioritised in lower extremity injury prevention programmes for team-sport athletes.

Editorial Commentary: Do Patients With Femoroacetabular Impingement Syndrome Already Show Hip Muscle Atrophy?

Muscle atrophy, fatty degeneration, and strength deficits of the hip abductors, flexors, and even external rotators are well-known clinical and radiologic findings in patients with advanced hip osteoarthritis. More recently, in the context of prearthritic hip diseases, the role of hip muscle function in femoroacetabular impingement syndrome (FAIS) has gained greater focus for hip surgeons. Several studies have shown that patients with FAIS present with activation deficits of the hip muscles, which may result in hip muscle weakness. Nevertheless, previous studies have yet to determine whether young and mainly active patients with FAIS already show hip muscle atrophy. Future research is required to further characterize hip muscle function in patients with FAIS. Of particular interest is the investigation of whether both qualitative (muscle fatty degeneration) and quantitative (muscle atrophy) morphologic alterations of the hip muscles are present in patients with FAIS, as well as whether these alterations are sex specific and/or related to the underlying hip morphology.

Pain, activities of daily living and sport function at different time points after hip arthroscopy in patients with femoroacetabular impingement: a systematic review with meta-analysis.

AIM: To investigate pain, activities of daily living (ADL) function, sport function, quality of life and satisfaction at different time points after hip arthroscopy in patients with femoroacetabular impingement (FAI). DESIGN: Systematic review with meta-analysis. Weighted mean differences between preoperative and postoperative outcomes were calculated and used for meta-analysis. DATA SOURCES: EMBASE, MEDLINE, SportsDiscus, CINAHL, Cochrane Library, and PEDro. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Studies that evaluated hip pain, ADL function, sport function and quality of life before and after hip arthroscopy and postoperative satisfaction in patients with symptomatic FAI. RESULTS: Twenty-six studies (22 case series, 3 cohort studies, 1 randomised controlled trial (RCT)) were included in the systematic review and 19 in the meta-analysis. Clinically relevant pain and ADL function improvements were first reported between 3 and 6 months, and sport function improvements between 6 months and 1 year after surgery. It is not clear when quality of life improvements were first achieved. On average, residual mild pain and ADL and sport function scores lower than their healthy counterparts were reported by patients following surgery. Postoperative patient satisfaction ranged from 68% to 100%. CONCLUSIONS: On average, patients reported earlier pain and ADL function improvements, and slower sport function improvements after hip arthroscopy for FAI. However, average scores from patients indicate residual mild hip pain and/or hip function lower than their healthy counterparts after surgery. Owing to the current low level of evidence, future RCTs and cohort studies should investigate the effectiveness of hip arthroscopy in patients with FAI. TRIAL REGISTRATION NUMBER: CRD42015019649.

Acute effects of multipath electrical stimulation in patients with total knee arthroplasty.

OBJECTIVE: To compare maximal evoked torque, discomfort, and fatigue-related outcomes between multipath neuromuscular electrical stimulation (NMES) and conventional NMES of the quadriceps muscle in patients with total knee arthroplasty (TKA). DESIGN: Randomized, single-blind, crossover study with 2 experimental sessions (multipath NMES, conventional NMES). SETTING: Research laboratory. PARTICIPANTS: Patients (N=20; mean age, 68y) 6 to 12 months after TKA surgery. INTERVENTIONS: None. MAIN OUTCOME MEASURES: We quantified NMES-evoked knee extension torque at the maximally tolerated current intensity, self-reported discomfort, and fatigue induced by NMES intermittent contractions in both conditions. RESULTS: Compared with conventional NMES, multipath NMES resulted in higher evoked torque (33%, P<.001), lower discomfort scores (-39%, P<.001), and less quadriceps muscle fatigue (P=.034). CONCLUSIONS: The use of multiple current pathways distributed to large electrodes allowed multipath NMES to generate stronger contractions and reduce discomfort and fatigue compared with conventional NMES. Therefore, multipath NMES has the potential to be more effective than conventional NMES.

Return to sport after hip surgery for femoroacetabular impingement: a systematic review.

BACKGROUND: We aimed to appraise (1) the rate of return to sport of athletes after hip surgery for femoroacetabular impingement (FAI) and (2) some aspects that may influence the return to sport. METHODS: Four databases (EMBASE, PubMed, Web of Science, Cochrane Library) were searched until 21 October 2014. Studies evaluated return to sport of athletes who underwent hip surgery for the treatment of symptomatic FAI. A validated tool was used for quality evaluation of the studies. RESULTS: A total of 18 case series (level of evidence IV) with moderate-to-high methodological quality were included. On average, 87% of athletes returned to sport after hip surgery for FAI and 82% returned to the same sport level as before the occurrence of the symptoms. Professional athletes seem to return to sport at a higher rate compared with recreational and collegiate athletes. Sport participation after hip arthroscopy tends to decrease for professional athletes at short-term and mid-term follow-ups. Diffuse hip osteoarthritis at the time of surgery may not allow athletes to return to sport. CONCLUSIONS: Most athletes return to sport after hip surgery for the treatment of symptomatic FAI. The level of competition, time of evaluation after hip surgery and presence of articular cartilage lesions at the time of surgery may influence return to sport. Future studies with higher levels of evidence should describe and evaluate return to sport protocols after hip surgery for FAI.

Assessment of the rate of force development scaling factor for the hip muscles.

INTRODUCTION: The aim of this study was to evaluate test feasibility, validity, and reproducibility of the rate of force development scaling factor (RFD-SF) for the hip muscles. METHODS: Feasibility was assessed as the testing compliance, validity as the ability to compute the RFD-SF from a linear regression, and reproducibility with a test-retest design in 20 healthy subjects. Reliability and agreement (reproducibility) were evaluated using intraclass correlation coefficient (ICC3,1) and percent standard error of measurement (SEM), respectively. RESULTS: The RFD-SF testing protocol was completed successfully by all subjects, although the analysis had to be modified for hip rotators. Reliability was high (ICC3,1 > 0.70) for all muscles except hip abductors (ICC3,1 = 0.69) and internal rotators (ICC3,1 = 0.58). Agreement was high for all muscles (SEM < 10%). CONCLUSIONS: Hip adductor, flexor, and external rotator RFD-SF can be evaluated with confidence, provided the analysis is modified for external rotators, whereas hip abductor and internal rotator RFD-SF assessment is not recommended.

Validity and reproducibility of the Physical Activity Scale for the Elderly (PASE) questionnaire for the measurement of the physical activity level in patients after total knee arthroplasty.

BACKGROUND: The need for valid and reproducible questionnaires to routinely assess the physical activity level of patients after total knee arthroplasty (TKA) is of particular concern in clinical settings. Aims of this study were to evaluate the validity and reproducibility of the physical activity scale for the elderly (PASE) questionnaire in TKA patients, with a particular view on gender differences. METHODS: A total of 50 elderly patients (25 women and 25 men aged 70 ± 6 years) following primary unilateral TKA were recruited. The reproducibility was evaluated by administering the PASE questionnaire during two occasions separated by 7 days. The construct (criterion) validity was investigated by comparing the physical activity level reported by patients in the PASE questionnaire to that measured by accelerometry. Reproducibility was evaluated using intraclass correlation coefficients (ICC3,1) for reliability and standard error of measurement (SEM) and smallest detectable change (SDC) for agreement, while validity was investigated with Pearson correlation coefficients. RESULTS: Reliability of the PASE total score was acceptable for men (ICC = 0.77) but not for women (ICC = 0.58). Its agreement was low for both men and women, as witnessed by high SEM (32% and 35%, respectively) and SDC (89% and 97%, respectively). Construct validity of the PASE total score was low in both men (r = 0.45) and women (r = 0.06). CONCLUSIONS: The PASE questionnaire has several validity and reproducibility shortcomings, therefore its use is not recommended for the assessment of physical activity level in patients after TKA, particularly in women.

Differences in gait characteristics between total hip, knee, and ankle arthroplasty patients: a six-month postoperative comparison.

BACKGROUND: The recovery of gait ability is one of the primary goals for patients following total arthroplasty of lower-limb joints. The aim of this study was to objectively compare gait differences of patients after unilateral total hip arthroplasty (THA), total knee arthroplasty (TKA) and total ankle arthroplasty (TAA) with a group of healthy controls. METHODS: A total of 26 TAA, 26 TKA and 26 THA patients with a mean (± SD) age of 64 (± 9) years were evaluated six months after surgery and compared with 26 matched healthy controls. Subjects were asked to walk at self-selected normal and fast speeds on a validated pressure mat. The following spatiotemporal gait parameters were measured: walking velocity, cadence, single-limb support (SLS) time, double-limb support (DLS) time, stance time, step length and step width. RESULTS: TAA and TKA patients walked slower than controls at normal (p<0.05) and fast speeds (p<0.01). The involved side of TAA and TKA patients showed shorter SLS compared to controls at both normal and fast speeds (p<0.01). Regardless of walking speed, the uninvolved side of TAA and TKA patients demonstrated longer stance time and shorter step length than controls (p<0.01). TAA patients showed shorter SLS of the involved side, longer stance time and shorter step length of the uninvolved side compared to the contralateral side at both normal and fast speeds (p<0.001). CONCLUSIONS: Gait disability after unilateral lower-limb joint arthroplasty was more marked for distal than for proximal joints at six months after surgery, with a proximal-to-distal progression in the impairment (TAA>TKA>THA). THA patients demonstrated no gait differences compared with controls. In contrast, TAA and TKA patients still demonstrated gait differences compared to controls, with slower walking velocity and reduced SLS in the involved limb. In addition, TAA patients presented marked side-to-side asymmetries in gait characteristics.

Sex-Specific Differences in Hip Muscle Cross-sectional Area and Fatty Infiltration in Patients With Femoroacetabular Impingement Syndrome.

Background: Patients with femoroacetabular impingement syndrome (FAIS) show sex-specific differences in hip muscle function, hip morphology, and symptoms. Possible differences in hip muscle characteristics between men and women with FAIS are unknown. Purpose: To compare hip muscle cross-sectional area (CSA) and fatty infiltration between men and women with FAIS and investigate possible associations with patient-reported outcomes. Study Design: Cohort study; Level of evidence, 3. Methods: We retrospectively analyzed preoperative axial pelvic magnetic resonance imaging scans of 104 patients (54 women) who underwent hip surgery for FAIS. The main outcome measures were side-to-side percentage asymmetry in hip muscle CSA and involved-side fatty infiltration as measured with the Goutallier scale for a total of 10 hip muscles. Patient-reported outcomes included duration of hip symptoms, iHOT-12 (12-item International Hip Outcome Tool), and Hip Sports Activity Scale. Results: Women showed larger hip abductor muscle CSA asymmetry than men (P = .018), particularly for the gluteus medius (P = .049), while men exhibited more fatty streaks (grade 1) in the gluteus medius (P = .015) than women. Duration of symptoms was associated only with fatty infiltration of obturator externus in men (r S = -0.55, P = .018). iHOT-12 was associated with CSA asymmetry of the gluteus minimus (r = -0.41, P = .011) and iliopsoas (r = -0.36, P = .028) in men and with piriformis fatty infiltration (r S = -0.56, P = .030) in women. The Hip Sports Activity Scale was associated with iliopsoas CSA asymmetry (r S = 0.32, P = .026) and with fatty infiltration of the tensor fasciae latae (r S = -0.45, P = .046) and obturator externus (r S = -0.50, P = .023) in women. Conclusion: Patients with FAIS demonstrated few sex-specific quantitative and qualitative alterations of hip muscles. Women showed greater hip abductor muscle atrophy than men, particularly for the gluteus medius, while men showed a higher degree of fatty infiltration in this same muscle. The duration of hip symptoms was not associated with muscle atrophy. Patient-reported hip pain/function and sport activity level were only moderately associated with isolated muscular variables.

Hip muscle strength in male and female patients with femoroacetabular impingement syndrome: Comparison to healthy controls and athletes.

OBJECTIVES: To examine hip muscle strength deficits in patients with femoroacetabular impingent syndrome (FAIS), with special emphasis on potential sex- and comparison-related (between-subject vs within-subject) differences. DESIGN: Cross-sectional comparative study. PARTICIPANTS: Forty FAIS patients (20 women), 40 healthy controls (20 women) and 40 athletes (20 women). MAIN OUTCOME MEASURES: Hip abduction, adduction and flexion isometric strength was tested using a commercially-available dynamometer. Two between-subject comparisons (FAIS patients vs controls and FAIS patients vs athletes) and one within-subject comparison (inter-limb asymmetry) of strength deficits were conducted, based on the calculation of respective percent differences. RESULTS: For all hip muscle groups, women were 14-18% weaker than men (p < 0.001), but no sex-related interactions were observed. For all hip muscle groups, FAIS patients were 16-19% weaker than controls (p = 0.001) and 24-30% weaker than athletes (p < 0.001). For FAIS patients, the involved hip abductors were 8.5% weaker than the uninvolved ones (p = 0.015), while no inter-limb asymmetry was observed for the other hip muscles. CONCLUSION: Sex had no influence on hip muscle strength deficits in FAIS patients while a major impact of comparison method/group was observed. Hip abductors showed consistent deficits for all comparison methods, suggestive of a possible greater impairment compared to hip flexors and adductors.

MME+ fibro-adipogenic progenitors are the dominant adipogenic population during fatty infiltration in human skeletal muscle.

Fatty infiltration, the ectopic deposition of adipose tissue within skeletal muscle, is mediated via the adipogenic differentiation of fibro-adipogenic progenitors (FAPs). We used single-nuclei and single-cell RNA sequencing to characterize FAP heterogeneity in patients with fatty infiltration. We identified an MME+ FAP subpopulation which, based on ex vivo characterization as well as transplantation experiments, exhibits high adipogenic potential. MME+ FAPs are characterized by low activity of WNT, known to control adipogenic commitment, and are refractory to the inhibitory role of WNT activators. Using preclinical models for muscle damage versus fatty infiltration, we show that many MME+ FAPs undergo apoptosis during muscle regeneration and differentiate into adipocytes under pathological conditions, leading to a reduction in their abundance. Finally, we utilized the varying fat infiltration levels in human hip muscles and found less MME+ FAPs in fatty infiltrated human muscle. Altogether, we have identified the dominant adipogenic FAP subpopulation in skeletal muscle.

Validity of the intelligent device for energy expenditure and activity accelerometry system for quantitative gait analysis in patients with hip osteoarthritis.

OBJECTIVE: To evaluate the concurrent validity of an accelerometry-based system (Intelligent Device for Energy Expenditure and Activity) with a criterion instrument (Gaitrite) for the evaluation of spatiotemporal gait variables in orthopedic patients. DESIGN: Validity study. SETTING: Research laboratory in an orthopedic hospital. PARTICIPANTS: Men with unilateral hip osteoarthritis (N=26; mean age ± SD, 54±9y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Patients were asked to walk at normal and fast velocities while gait cycle, swing, double support, step length, cadence, and speed were concomitantly recorded with the 2 instruments. Concurrent criterion-related validity was examined using intraclass correlation coefficients and Bland-Altman limits of agreement. RESULTS: Intraclass correlation coefficients were acceptable for all gait parameters (range, .815-.997), except step length (.783). Limits of agreement were low for gait cycle, swing, and cadence, though relatively high for double support, step length, and speed. A significant bias between the 2 measuring instruments was consistently observed. CONCLUSIONS: In patients with hip osteoarthritis, quantitative gait analysis with the IDEEA accelerometry system was satisfactory for the main temporal gait parameters, while double support, step length, and walking speed quantifications were invalid. The IDEEA system should be used with caution, and modifications of the system are recommended for improved use in clinical practice and research.