Systematic Review
Global Discrepancies in the Diagnosis, Surgical Management, and Investigation of Femoroacetabular Impingement Marco Yeung, M.D., Moin Khan, M.D., Verena M. Schreiber, M.D., John Adamich, BH.Sc. candidate, Shelby Letkemann, P.A. candidate, Nicole Simunovic, M.Sc., Mohit Bhandari, M.D., Ph.D., F.R.C.S.C., Volker Musahl, M.D., Marc J. Philippon, M.D., Marc R. Safran, M.D., and Olufemi R. Ayeni, M.D., M.Sc., F.R.C.S.C.
Purpose: The purpose of this study was to review the global pattern of surgical management of femoroacetabular impingement (FAI), particularly in diagnosis, outcome measurement, and management. Methods: We performed a systematic search in duplicate for surgical studies addressing FAI published up to June 2013. Study parameters, including sample size, study location, surgical intervention technique, diagnostic imaging, outcome measures used, sex distribution, and level of evidence, were obtained. The number of trials and cumulative sample size were analyzed. The surgical interventions, sex distribution, outcome measures, and diagnostic imaging used were compared between geographic regions. Results: We identified 105 studies reporting surgical interventions for FAI. Most studies were completed in North America (52 studies, 3,629 patients) and in Europe (44 studies, 3,745 patients). Asia (3 studies, 49 patients) and Oceania (6 studies, 394 patients) had smaller contributions. There were no studies from South America or Africa. Most research performed in North America, Europe, and Oceania investigated arthroscopic FAI surgery (55% of studies) followed by surgical dislocation (33%), and miniopen (15%) and combined approaches (8%). Methods of diagnosis were consistent worldwide, with radiography being the mainstay of diagnosis (84% of studies). Case series were the most common type of study globally (75% of studies). Outcome measures varied by region; Harris hip scores were most common in North America, Oceania, and Asia, whereas Non-Arthritic Hip Scores and Western Ontario McMaster scores predominated in Europe. Conclusions: Global surgical trends for FAI show a predominance of North American and European studies, studies of lower level evidence, and inconsistent use of outcome measures. However, patterns of diagnostic imaging, sex proportions, and predominance of arthroscopic techniques are consistent worldwide. Future research should focus on development of reliable validated outcome measures and international collaboration to conduct high-quality research and improve our understanding of FAI diagnosis and management. Level of Evidence: Level IV, systematic review of Level I-IV studies.
nterest in femoroacetabular impingement (FAI)d particularly the nature of the disease as well as its surgical optionsdhas blossomed in the past decade since it was described by Ganz et al.,1 with an exponential increase in FAI-related publications in recent
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years.2 Surgical intervention for FAI is designed to correct the impingement lesions by removing excess bone and bony prominences, as well as addressing associated pathologic conditions such as chondral and labral injuries, to prevent the progressive degenerative
Division of Orthopedic Surgery and Department of Clinical Epidemiology and Biostatistics, McMaster University (M.Y., M.K., J.A., S.L., N.S., M.B., O.R.A.), Hamilton, Ontario, Canada; Division of Orthopedic Surgery, University of Pittsburgh (V.M., V.M.S.), Pittsburgh, Pennsylvania; The Steadman Clinic (M.J.P.), Vail, Colorado; and Division of Orthopedic Surgery, Stanford University (M.R.S.), Stanford, California, U.S.A. The authors report the following potential conflict of interest or source of funding in relation to this article: M.B. receives support from Smith & Nephew, Stryker, Amgen, Zimmer, Moximed, Bioventus, DePuy, and Eli Lily. M.J.P. receives support from Steadman Philippon Research Institute, Smith & Nephew, MIS, Ossur, Siemens, Vail Valley Medical Center, Arthrosurface, DonJoy, Linvatec, and HIPCO. M.R.S. receives support from
ConMed Linvatec, Biomimedica, Cool Systems, Subchondral Solutions, Ferring Pharmaceuticals, Smith & Nephew, Ossur, Stryker, Arthrocare, and DJO. Received March 20, 2014; accepted June 2, 2014. Address correspondence to Marco Yeung, M.D., Department of Orthopaedic Surgery, HHS Hamilton General Hospital, Residency Office HGH 8N06, 237 Barton Street East, Hamilton ON L8L 2X2, Canada. E-mail: marco.yeung@ medportal.ca Ó 2014 by the Arthroscopy Association of North America 0749-8063/14233/$36.00 http://dx.doi.org/10.1016/j.arthro.2014.06.008
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effects the impingement has on the hip joint. However, surgical approaches described in the literature to treat FAI have been variable. Surgical hip dislocation, hip arthroscopy, miniopen surgical approaches, and combined approaches have been successfully used to treat FAI. Similarly, significant variation in reported clinical outcome measures used in the assessment of FAI has been noted previously.3 Substantial differences in geographic contributions to hip fracture studies have been shown, and such may be the case with the FAI literature as well.4 No review to date has investigated the geographic trends in surgical management of FAI in the literature. The goal of our systematic review was to investigate the global trends of surgical management in the FAI literaturedspecifically, the geographic distribution of surgical FAI studies, the types of FAI surgery used, and geographic differences in diagnostic imaging, sex distribution, and reported outcome measures. We hypothesized that most FAI surgery in the literature is performed in the United States and Europe, where most surgical techniques for FAI have been developed. Furthermore, we postulated that regional differences exist with regard to type of intervention used, diagnostic imaging, and clinical outcomes studied because of different practice patterns.
Methods The inclusion criteria for this systematic review were as follows: (1) studies of human patients including all ages and both sexes, (2) studies reporting clinical outcomes of surgical management of FAI in which all patients had a diagnosis of FAI, and (3) studies of all languages pertaining to FAI. Exclusion criteria were (1) review articles, (2) diagnostic studies, (3) case reports and studies with fewer than 5 patients, and (4) studies exclusively investigating secondary causes of FAI, such as impingement caused by hip fracture fixation and slipped capital femoral epiphysis. A title and abstract review to screen for eligible studies was completed in duplicate. A full-text review was then conducted, also in duplicate, and references were hand searched for other eligible studies. Any discrepancies regarding inclusion were resolved through discussion and consensus between reviewers (M.Y., J.A.). Electronic databases (MEDLINE, EMBASE, and Cochrane Library) were searched for surgical FAI studies from 1946 up to June 2013 when the search was performed. The search strategy used the following search terms: (1) “femoroacetabular impingement” or “femoracetabular impingement,” “cervicoacetabular impingement” or “hip impingement” or “femoral acetabular impingement” AND (2) “arthroscopy” or “surgery.” The “femoracetabular impingement [Surgery]” subheading in MEDLINE and the “femoroacetabular impingement
[Surgery]” subheading in EMBASE were also searched. The results were uploaded to a bibliographic management database (RefWorks, version 2.0; Bethesda, MD). Data were collected from the included articles by 2 reviewers (M.Y., S.L.). Abstracted data included the following information: title, author, year of publication, location (city, country, continent), sample size, number of male and female patients, mean age, length of follow-up, levels of evidence, type of intervention studied, type of diagnostic imaging used, and outcome measures reported. Descriptive statistics concerning the numbers of randomized controlled trial publications and total sample population studied, sex ratio, type of diagnostic imaging used, reported outcome measures, and level of evidence used were computed by continent. The computer-generated maps were created using Tableau visual data analysis software (Seattle, WA). The cumulative sample sizes studied per city were imported into the mapping software. The software graphically represented the value as a circle at the geographic location of the city, with the area of the circle proportional to the numeric value of cumulative sample size at that city.
Results Our electronic searches yielded 1,411 studies, with 105 studies found to meet the inclusion criteria; these studies were included in the analysis (Fig 1). All 105 included studies were published between 2004 and 2013. A total of 7,880 patients with FAI were managed surgically across all included studies. Most studies investigated arthroscopic intervention (57 studies), followed by open surgical dislocation (34 studies), miniopen approaches (16 studies), combined approaches (8 studies), and periacetabular osteotomy (2 studies). Fifty-two studies (3,629 patients) were performed in North America, 44 studies (3,745 patients) were performed in Europe, 6 studies (394 patients) were performed in Oceania, and 3 studies (49 patients) were performed in Asia. There were no studies found from the continents of South America and Africa (Table 1 and Fig 2). Most studies investigated arthroscopic intervention (57 studies, 5,059 patients), followed by open surgical dislocation (34 studies, 1,437 patients), miniopen approaches (16 studies, 890 patients), combined approaches (8 studies, 254 patients), and periacetabular osteotomy (2 studies, 73 patients) (Table 2). In North America, 73% (2,648 patients) of patients underwent arthroscopic intervention, compared with 11% (407 patients) who underwent surgical dislocation, 10% (372 patients) who underwent miniopen procedures, 7% (253 patients) who underwent combined procedures, and 2% (73) who underwent periacetabular
GLOBAL DISCREPANCIES IN FAI SURGERY
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Fig 1. Summary of the literature search and inclusion/exclusion process.
osteotomy (Fig 3). In Europe, 57% (2,075 patients) of patients underwent arthroscopic intervention, 26% (933 patients) underwent open surgical dislocation, 16% (566 patients) underwent miniopen procedures, and 2% (59 patients) underwent combined procedures. In Oceania, 88% (346 patients) underwent arthroscopic intervention and 12% (46 patients) underwent open surgical dislocation. All patients in studies from Asia (49 patients) underwent surgical hip dislocation. Overall, 91 studies reported the use of radiography and 65 studies reported the use of magnetic resonance imaging (MRI) for diagnosis of FAI. A smaller proportion of studies (25 studies) reported the use of computed tomography (CT) for diagnosis and assessment of FAI. Of the North American studies, 48 studies (92%) reported the use of radiography, whereas 33 studies (63%) reported MRI use, and 15 (29%) reported the use of CT. In Europe, 34 studies (77%) reported the use of radiography, 26 studies (59%) reported the use of MRI, and 5 studies (11%) reported CT use. In Oceania, all 6 studies used radiography, whereas 4 studies (67%) used MRI and CT. In the Asian studies, all 3 studies used radiography, whereas 2 studies (67%) reported MRI use, and one study (33%) reported CT use.
The overall sex ratio of the entire study population was 61:39 male to female patients. The North American population had a sex ratio of 60:40. In Europe, the male to female ratio was 59:41. In Oceania, the sex ratio of male to female patients was 77:23. The Asian population had a sex ratio of 78:22. The most commonly used reported outcome measure in all studies was the Harris Hip Score (HHS), with the modified Harris Hip Score (mHHS) used in 32 studies (30.5%) and the original HHS used in 17 studies (16.2%), Other commonly used reported outcome measures were clinical range of motion, used in 28 studies (26.7%), the Non-Arthritic Hip Score (NAHS), used in 23 studies (21.9%), and the Western Ontario and McMaster University score (WOMAC), used in 21 studies (20%). Other clinical outcome measures used are listed in Table 3. Common radiologic outcomes were the alpha angle, used in 30 studies (28.6%), degenerative changes, reported in 20 studies (19.0%), and head-neck offset, used in 8 studies (7.6%). Other radiologic outcomes are reported in Table 4. Over the years, various measures such as mHHS and hip outcome scores have become popular for outcome analysis in surgical FAI studies (Fig 4).
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Table 1. Geographic Distribution of Surgical Femoroacetabular Impingement Studies Geographic Region North America Canada Mexico United States Europe France Germany Italy Spain Switzerland United Kingdom Oceania Australia New Zealand Asia South Korea Turkey South America e Africa e
Number of Studies 52 5 2 45 44 6 7 1 3 19 8 6 5 1 3 1 2 0 e 0 e
Sample Size Studied (No. of Patients) 3,629 82 124 3,404 3,745 473 248 8 151 1,654 1,211 394 346 48 49 14 35 0 e 0 e
In North America, the most commonly used outcome measures were the mHHS score, used in 21 studies (40%), and the HHS, used in 7 studies (13%). European studies most commonly used WOMAC and NAHSd15 (34.9%) and 14 (32.6%) of studies, respectively. Oceania most commonly used mHHS and NAHS; each was used in 5 studies (83.3%). Asia used
HHS in all 3 studies from the region. Common clinical outcome measures and frequency of use by region are listed in Table 3. Alpha angle was the most commonly used radiographic outcome in all regions. Other common radiologic outcome measures by region are shown in Table 4. Most of the 105 studies located were case series of Level IV evidence (76%), whereas retrospective cohorts (Level III evidence), prospective cohorts (Level II evidence), and randomized controlled trials (Level 1 evidence) were less common (Table 2). Case series made up 75% of North American studies (39 studies), 68.2% of European studies (30 studies), 57.1% of Oceanic studies (4 studies), and 100% of Asian studies (3 studies). Level III evidence constituted 11.5% (6 studies) of the North American cohort, 18.2% (8 studies) of the European cohort, and 14.3% (1 study) of the Oceania cohort but were absent in Asian studies. Level II evidence made up 11.5% (6 studies) of North American studies, 13.6% (6 studies) of European studies, 14.3% (1 study) of studies from Oceania, and was absent in the Asian cohort. Only 2 studies of Level I evidence were founddone from North America and the other from Oceania.
Discussion Key Findings This systematic review evaluated the global diagnostic and treatment trends addressing FAI. We found that most published FAI studies were carried out in Europe
Fig 2. Geographic distribution of surgical studies in femoroacetabular impingement by sample size.
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GLOBAL DISCREPANCIES IN FAI SURGERY Table 2. Global Trends of Surgical Studies in Femoroacetabular Impingement (By Continent) Study Characteristic Studies Total sample size (no. of patients) Surgical intervention (no. of patients undergoing intervention) Arthroscopic Surgical dislocation Miniopen Combined Periacetabular osteotomy Diagnostic imaging (no. of studies used) Radiography MRI CT Most commonly used outcome measures (percentage of studies used) Sex ratio (M:F as ratio of 100) Level of Evidence Level I Level II Level III Level IV
North America 52 (49.5%) 3,629 (46.4%)
Europe 44 (41.9%) 3,745 (47.9%)
Oceania 6 (5.7%) 394 (5.0%)
Asia 3 (2.9%) 49 (0.6%)
South America 0 0
Africa 0 0
2,638 407 324 195 73
(73%) (11%) (9%) (5%) (2%)
2,075 933 372 253
346 (88%) 48 (12%) e e e
e 49 (100%) e e e
e e e e e
e e e e e
48 33 15 mHHS
(92%) (63%) (29%) (40%)
3 (100%) 2 (67%) 1 (33%) mHHS (83%) NAHS (83%) 78:22
e e e e
e e e e
e e e e e e
e e e e e e
60:40 1 6 6 39
(2%) (11.5%) (11.5%) (75%)
(57%) (26%) (10%) (7%) e
34 (77%) 26 (59%) 5 (11%) WOMAC (35%) NAHS (33%) 59:41 0 6 8 30
(0%) (13.6%) (18.2%) (68.2%)
6 4 4 HHS
(100%) (67%) (67%) (100%)
77:23 1 1 1 4
(14.3%) (14.3%) (14.3%) (57.1%)
0 0 0 3
(0%) (0%) (0%) (100%)
NOTE. Data presented as n (%) unless otherwise indicated. CT, computed tomography; HHS, Harris Hip Score; mHHS, modified Harris Hip Score; MRI, magnetic resonance imaging; NAHS, Non-Arthritis Hip Score; WOMAC, Western Ontario and McMaster University score.
and North America, which may result from a number of reasons. First, various factors affect the output of surgical publications, including availability of research resources, research spending, health care infrastructure, population size, and proficiency in the English language.5,6 Many of the countries in which FAI research
Fig 3. Breakdown of patients in surgical femoroacetabular impingement (FAI) studies by surgical technique.
was published rank high in research expenditure per gross domestic product and are English proficient. It has also been postulated that FAI and resultant osteoarthritis may be genetically linked, predisposing particular populations with European ancestry.7 Various FAI cohorts identified a predominance of white patients,
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Table 3. Global Trends of Clinical Outcome Measure Use in Surgical Studies in Femoroacetabular Impingement (By Continent) Clinical Outcome Measure Complications Revisions Conversion to total hip arthroplasty mHHS Range of motion NAHS WOMAC VAS pain scale Satisfaction Impingement sign HHS Return to sport Merle d’Aubigne Hip Outcome Score SF12 Pain Kinematic measurements SF36 Oxford hip score Tegner activity score Dexeus score Return to work UCLA score SUSHI (Super Simple Hip Score) Procedure time Hospital stay Return to activities of daily living Global treatment outcome Rosser quality of life Devane activity scale Length of scar Blood loss Christensen score Return to practice Return to preoperative strength Sports frequency score EQ5D (Euroqol 5 dimensions) Symptom-specific well-being Expectations Hip Sports Activity Scale Level of sports activity Subjective hip value Hip abductor strength
North America 40 (76.9%) 34 (65.4%) 27 (51.9%) 21 (40.4%) 11 (21.2%) 4 (7.7%) 7 (13.5%) 8 (15.4%) 7 (13.5%) 7 (13.5%) 7 (13.5%) 8 (15.4%) 3 (5.8%) 8 (15.4%) 7 (13.5%) 4 (7.7%) 4 (7.7%) 2 (3.8%) e 3 (5.8%) 1 (1.9%) e e 2 (3.8%) e e e e e e e e e e e e e e e e e e e
Europe 27 (62.8%) 23 (53.5%) 15 (34.9%) e 15 (34.9%) 14 (32.6%) 15 (34.9%) 11 (25.6%) 7 (16.3%) 8 (18.6%) 7 (16.3%) 5 (11.6%) 9 (20.9%) 3 (7.0%) 2 (4.7%) 2 (4.7%) e 2 (4.7%) 4 (9.3%) e 2 (4.7%) 3 (7.0%) 3 (7.0%) e 2 (4.7%) 2 (4.7%) 2 (4.7%) 2 (4.7%) 2 (4.7%) 1 (2.3%) 1 (2.3%) 1 (2.3%) 1 (2.3%) 1 (2.3%) 1 (2.3%) 1 (2.3%) 1 (2.3%) 1 (2.3%) 1 (2.3%) 1 (2.3%) 1 (2.3%) 1 (2.3%) 1 (2.3%)
Oceania 5 (83.3%) 5 (83.3%) 3 (50.0%) 5 (83.3%) 1 (16.7%) 5 (83.3%) 1 (16.7%) e 3 (50.0%) 1 (16.7%) e 2 (33.3%) e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e
Asia 3 (100.0%) 2 (66.6%) 1 (33.3%) e 1 (33.3%) e e e 1 (33.3%) 2 (66.6%) 3 (100.0%) e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e
South America e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e
Africa e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e
75 64 46 32 28 23 23 19 18 18 17 15 12 11 9 6 4 4 4 3 3 3 3 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1
Total (71.4%) (61.0%) (43.8%) (30.5%) (26.7%) (21.9%) (21.9%) (18.1%) (17.1%) (17.1%) (16.2%) (14.3%) (11.4%) (10.5%) (8.6%) (5.7%) (3.8%) (3.8%) (3.8%) (2.9%) (2.9%) (2.9%) (2.9%) (1.9%) (1.9%) (1.9%) (1.9%) (1.9%) (1.9%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%)
NOTE. Data presented as n (%). HHS, Harris Hip Score; mHHS, modified Harris Hip Score; NAHS, Non-Arthritis Hip Score; SF12, 12-item short-form survey; SUSHI, Super Simple Hip Score; UCLA, University of California, Los Angeles; VAS, visual analog scale; WOMAC, Western Ontario and McMaster University score.
composing 79% to 88% of the FAI population.8 This ethnic predisposition could explain the increased surgical incidence in regions that have significant populations of European descent and the converse in African and Asian regions. However, the findings of this study also beg the question of whether FAI is a disease of the affluent or a clinical phenomenon seen in patients in developed regions with functional disabilities in sports and other such recreational activities and not a disease entity that is diagnosed and surgically treated in developing nations. Many of the countries where this research is occurring are also places where athletic
participation is quite vibrant, and it has been postulated that FAI may be the result of athletic participation while individuals are young.9 Furthermore, limited health care resources are focused more on acute medical conditions. This geographic discrepancy of FAI research may also reflect the current stage of surgical innovation in FAI. It has been suggested by experts in surgical research that in early stages of innovation, the research landscape primarily consists of case series conducted by opinion leaders, which is similar to the results of this study regarding available FAI literature.10 As surgical management of FAI continues to mature, we anticipate
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GLOBAL DISCREPANCIES IN FAI SURGERY Table 4. Global Trends of Radiographic Outcome Measure Use in Surgical Studies in Femoroacetabular Impingement (By Continent) Radiographic Outcome Measure Alpha angle Degenerative changes Head-neck offset Crossover sign Center-edge angle Caput-collum-diaphyseal angle Tonnis angle Extrusion index Head-neck offset ratio Posterior wall sign Resection depth Resection depth ratio Acetabular depth Signs of avascular necrosis on MRI Articulotrochanteric distance Heymann and Herndon femoral head-neck index Triangular index Acetabular index Ischial spine sign Ischial spine prominence Resection width Acetabular coverage angle
North America 13 (25.0%) 9 (17.3%) 4 (7.7%) 6 (11.5%) 4 (7.7%) 1 (1.9%) 2 (3.8%) 1 (1.9%) 1 (1.9%) 1 (1.9%) e e 1 (1.9%) 1 (1.9%) e e e e e e e
Europe 16 (37.2%) 11 (25.6%) 4 (9.3%) 1 (2.3%) 2 (4.7%) 2 (4.7%) 1 1 1 2 2 2
(2.3%) (2.3%) (2.3%) (4.7%) (4.7%) (4.7%)
1 1 1 1 1 1 1
(2.3%) (2.3%) (2.3%) (2.3%) (2.3%) (2.3%) (2.3%)
Oceania e e e e e e e e e e e e e e e e e e e e e e
Asia 1 (33.3%) e e e e e e e e e e e e e e e e e e e e e
South America e e e e e e e e e e e e e e e e e e e e e e
Africa e e e e e e e e e e e e e e e e e e e e e e
30 20 8 7 6 3 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1
Total (28.6%) (19.0%) (7.6%) (6.7%) (5.7%) (2.9%) (1.9%) (1.9%) (1.9%) (1.9%) (1.9%) (1.9%) (1.9%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%)
NOTE. Data presented as n (%). HOS, hip outcome scores; MDA, Merle d’Aubigne score; MRI, magnetic resonance imaging.
an increase in the presence of methodologically rigorous research such as randomized trials. Arthroscopic interventions for FAI were most common in most continents. Similarly, the pattern of diagnostic imaging use was fairly consistent between regions. Radiographic assessment was most commonly used globally, which is not surprising given its accessibility, relative ease to perform, and low cost. Sex ratios were similar across geographic regions, with an overall male to female ratio of 61:39. These
Fig 4. Clinical outcome measures in femoroacetabular impingement studies by year. (HHS, Harris Hip Score; HOS, hip outcome scores; MDA, Merle d’Aubigne score; mHHS, modified Harris Hip Score; NAHS, Non-Arthritic Hip Score; UCLA, University of California, Los Angeles; WOMAC, Western Ontario and McMaster University score.
results are consistent with previous systematic reviews of the FAI literature, which have also shown a maledominant population.11,12 We also found variability in reported outcome measures in the FAI literature. This echoes the results of a systematic review by Hetaimish et al.,3 which also showed significant variability in reported outcome measures in the FAI literature. Our findings also noted geographic discrepancies in the reporting of outcome measures, with mHHS being used most commonly in North America compared with WOMAC and NAHS in Europe. The findings of this study emphasize the need for consistent outcome assessment and reporting with tools developed and validated to assess nonarthritic hip pain in the young adult. Further, these outcomes tools need to be validated cross-culturally to globally standardize outcome reporting. Future Directions The geographic discrepancy seen in outcome measures used in FAI studies underscores limitations in our ability to assess and compare our surgical results and outcomes. Future directions should include attempts to use a validated and standardized outcome measure in surgical FAI studies that can be applied and used globally. Two outcomes toolsdthe International Hip Outcome Tool (iHOT-33) scale and the Copenhagen Hip and Groin Outcome Score (HAGOS)drecently have been published that fulfill these criteria, yet they were published after the studies reviewed were
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undertaken.13,14 Assessment of the utility of these outcome measures using the Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN) tool has shown promise in new tools such as the International Hip Outcome Tool and HAGOS scales but have ascertained that further study needs to be performed to study the effectiveness of these tools to identify change in longitudinal FAI cohorts.15 Further comparisons should be performed to identify the most effective outcome tool, and, furthermore, researchers worldwide will need to come to a consensus on a standardized measure to be used consistently across the world.
research. We found FAI research globally is predominated by studies of low-level evidence, primarily conducted in North America and Europe, with a lack of outcome measure standardization. Encouragingly, patterns of diagnostic imaging and sex proportions, as well as the predominance of arthroscopic techniques, are consistent across geographic regions. This review shows the potential for globally collaborative highlevel research in FAI and highlights the need for developing reliable validated outcome measures to assess FAI outcomes internationally.
Strengths and Limitations There were several strengths to this systematic review. First, multiple reviewers (M.Y., J.A., S.L.) were involved in the screening of studies and abstraction of data from our literature search. Second, we used a broad-based search strategy resulting in a comprehensive search of multiple databases. We also did not limit our search to English articles and thus improved the breadth of our search and ensured accurate geographic representation in our study. However, some limitations do exist with this review. A small number of the studies that otherwise may have met our inclusion criteria did not have locatable fulltext articles despite an extensive search, and this may have affected the distributions we found in our results. Furthermore, some authors were involved in multiple studies, and despite our attempts to contact the authors, we were unable to confirm if there was any overlap in the patient population between studies. Finally, surgical intervention for FAI may be occurring in Africa or South America, but despite an exhaustive search, results or publications, or both, on this population are pending or unreported. The absence of studies and publications in Africa and South America and the dearth of similar research in Asia highlight the scarcity of information about FAI in these parts of the world. Further research should be performed in these geographic regions to provide foundational information about regional trends in methods of diagnosis and surgical management. Such investigations regarding the pattern of diagnosis could also help identify the reason for the geographic disparity found in our study. Is FAI not as prevalent in certain ethnicities and genotypes? Is FAI a disease of affluence that is infrequent in the developing world, or are there issues surrounding lack of access to imaging, diagnostic tools, and surgical expertise in these areas?
1. Ganz R, Parvizi J, Beck M, Leunig M, Nötzli H, Siebenrock KA. Femoroacetabular impingement: A cause for osteoarthritis of the hip. Clin Orthop Relat Res 2003;417: 112-120. 2. Ayeni OR, Chan K, Al-Asiri J, et al. Sources and quality of literature addressing femoroacetabular impingement. Knee Surg Sports Traumatol Arthrosc 2013;21:415-419. 3. Hetaimish BM, Khan M, Crouch S, et al. Consistency of reported outcomes after arthroscopic management of femoroacetabular impingement. Arthroscopy 2013;29: 780-787. 4. Yeung M, Bhandari M. Uneven global distribution of randomized trials in hip fracture surgery. Acta Orthop 2012;83:328-333. 5. Man JP, Weinkauf JG, Tsang M, Sin DD. Why do some countries publish more than others? An international comparison of research funding, English proficiency and publication output in highly ranked general medical journals. Eur J Epidemiol 2004;19:811-817. 6. Van Rossum M, Bosker B, Pierik E, Verheyen C. Geographic origin of publications in surgical journals. Br J Surg 2007;94:244-247. 7. Hoaglund FT. Primary osteoarthritis of the hip: A genetic disease caused by European genetic variants. J Bone Joint Surg Am 2013;95:463-468. 8. Clohisy JC, Baca G, Beaulé PE, et al. Descriptive epidemiology of femoroacetabular impingement: A North American cohort of patients undergoing surgery. Am J Sports Med 2013;41:1348-1356. 9. Byrd JW. Femoroacetabular impingement in athletes: Current concepts. Am J Sports Med 2014;42:737-751. 10. Barkun J, Aronson J, Feldman L, Maddern G, Strasberg S. Surgical innovation and evaluation 1: Evaluation and stages of surgical innovation. Lancet 2009;374:1089-1096. 11. Clohisy JC, St John LC, Schutz AL. Surgical treatment of femoroacetabular impingement: A systematic review of the literature. Clin Orthop Relat Res 2010;468:555-564. 12. Alradwan H, Philippon MJ, Farrokhyar F, et al. Return to preinjury activity levels after surgical management of femoroacetabular impingement in athletes. Arthroscopy 2012;28:1567-1576. 13. Mohtadi NG, Griffin DR, Pedersen ME, et al. The development and validation of a self-administered quality-oflife outcome measure for young, active patients with
Conclusions This systematic review shows significant geographic discrepancies in the contributions of surgical FAI
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15. Harris-Hayes M, McDonough CM, Leunig M, Lee CB, Callaghan JJ, Roos EM. Clinical outcomes assessment in clinical trials to assess treatment of femoroacetabular impingement: Use of patient-reported outcome measures. J Am Acad Orthop Surg 2013;21: S39-46 (suppl 1).
Global Discrepancies in the Diagnosis, Surgical Management, and Investigation of Femoroacetabular Impingement Marco Yeung, M.D., Moin Khan, M.D., Verena M. Schreiber, M.D., John Adamich, BH.Sc. candidate, Shelby Letkemann, P.A. candidate, Nicole Simunovic, M.Sc., Mohit Bhandari, M.D., Ph.D., F.R.C.S.C., Volker Musahl, M.D., Marc J. Philippon, M.D., Marc R. Safran, M.D., and Olufemi R. Ayeni, M.D., M.Sc., F.R.C.S.C.
Purpose: The purpose of this study was to review the global pattern of surgical management of femoroacetabular impingement (FAI), particularly in diagnosis, outcome measurement, and management. Methods: We performed a systematic search in duplicate for surgical studies addressing FAI published up to June 2013. Study parameters, including sample size, study location, surgical intervention technique, diagnostic imaging, outcome measures used, sex distribution, and level of evidence, were obtained. The number of trials and cumulative sample size were analyzed. The surgical interventions, sex distribution, outcome measures, and diagnostic imaging used were compared between geographic regions. Results: We identified 105 studies reporting surgical interventions for FAI. Most studies were completed in North America (52 studies, 3,629 patients) and in Europe (44 studies, 3,745 patients). Asia (3 studies, 49 patients) and Oceania (6 studies, 394 patients) had smaller contributions. There were no studies from South America or Africa. Most research performed in North America, Europe, and Oceania investigated arthroscopic FAI surgery (55% of studies) followed by surgical dislocation (33%), and miniopen (15%) and combined approaches (8%). Methods of diagnosis were consistent worldwide, with radiography being the mainstay of diagnosis (84% of studies). Case series were the most common type of study globally (75% of studies). Outcome measures varied by region; Harris hip scores were most common in North America, Oceania, and Asia, whereas Non-Arthritic Hip Scores and Western Ontario McMaster scores predominated in Europe. Conclusions: Global surgical trends for FAI show a predominance of North American and European studies, studies of lower level evidence, and inconsistent use of outcome measures. However, patterns of diagnostic imaging, sex proportions, and predominance of arthroscopic techniques are consistent worldwide. Future research should focus on development of reliable validated outcome measures and international collaboration to conduct high-quality research and improve our understanding of FAI diagnosis and management. Level of Evidence: Level IV, systematic review of Level I-IV studies.
nterest in femoroacetabular impingement (FAI)d particularly the nature of the disease as well as its surgical optionsdhas blossomed in the past decade since it was described by Ganz et al.,1 with an exponential increase in FAI-related publications in recent
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years.2 Surgical intervention for FAI is designed to correct the impingement lesions by removing excess bone and bony prominences, as well as addressing associated pathologic conditions such as chondral and labral injuries, to prevent the progressive degenerative
Division of Orthopedic Surgery and Department of Clinical Epidemiology and Biostatistics, McMaster University (M.Y., M.K., J.A., S.L., N.S., M.B., O.R.A.), Hamilton, Ontario, Canada; Division of Orthopedic Surgery, University of Pittsburgh (V.M., V.M.S.), Pittsburgh, Pennsylvania; The Steadman Clinic (M.J.P.), Vail, Colorado; and Division of Orthopedic Surgery, Stanford University (M.R.S.), Stanford, California, U.S.A. The authors report the following potential conflict of interest or source of funding in relation to this article: M.B. receives support from Smith & Nephew, Stryker, Amgen, Zimmer, Moximed, Bioventus, DePuy, and Eli Lily. M.J.P. receives support from Steadman Philippon Research Institute, Smith & Nephew, MIS, Ossur, Siemens, Vail Valley Medical Center, Arthrosurface, DonJoy, Linvatec, and HIPCO. M.R.S. receives support from
ConMed Linvatec, Biomimedica, Cool Systems, Subchondral Solutions, Ferring Pharmaceuticals, Smith & Nephew, Ossur, Stryker, Arthrocare, and DJO. Received March 20, 2014; accepted June 2, 2014. Address correspondence to Marco Yeung, M.D., Department of Orthopaedic Surgery, HHS Hamilton General Hospital, Residency Office HGH 8N06, 237 Barton Street East, Hamilton ON L8L 2X2, Canada. E-mail: marco.yeung@ medportal.ca Ó 2014 by the Arthroscopy Association of North America 0749-8063/14233/$36.00 http://dx.doi.org/10.1016/j.arthro.2014.06.008
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effects the impingement has on the hip joint. However, surgical approaches described in the literature to treat FAI have been variable. Surgical hip dislocation, hip arthroscopy, miniopen surgical approaches, and combined approaches have been successfully used to treat FAI. Similarly, significant variation in reported clinical outcome measures used in the assessment of FAI has been noted previously.3 Substantial differences in geographic contributions to hip fracture studies have been shown, and such may be the case with the FAI literature as well.4 No review to date has investigated the geographic trends in surgical management of FAI in the literature. The goal of our systematic review was to investigate the global trends of surgical management in the FAI literaturedspecifically, the geographic distribution of surgical FAI studies, the types of FAI surgery used, and geographic differences in diagnostic imaging, sex distribution, and reported outcome measures. We hypothesized that most FAI surgery in the literature is performed in the United States and Europe, where most surgical techniques for FAI have been developed. Furthermore, we postulated that regional differences exist with regard to type of intervention used, diagnostic imaging, and clinical outcomes studied because of different practice patterns.
Methods The inclusion criteria for this systematic review were as follows: (1) studies of human patients including all ages and both sexes, (2) studies reporting clinical outcomes of surgical management of FAI in which all patients had a diagnosis of FAI, and (3) studies of all languages pertaining to FAI. Exclusion criteria were (1) review articles, (2) diagnostic studies, (3) case reports and studies with fewer than 5 patients, and (4) studies exclusively investigating secondary causes of FAI, such as impingement caused by hip fracture fixation and slipped capital femoral epiphysis. A title and abstract review to screen for eligible studies was completed in duplicate. A full-text review was then conducted, also in duplicate, and references were hand searched for other eligible studies. Any discrepancies regarding inclusion were resolved through discussion and consensus between reviewers (M.Y., J.A.). Electronic databases (MEDLINE, EMBASE, and Cochrane Library) were searched for surgical FAI studies from 1946 up to June 2013 when the search was performed. The search strategy used the following search terms: (1) “femoroacetabular impingement” or “femoracetabular impingement,” “cervicoacetabular impingement” or “hip impingement” or “femoral acetabular impingement” AND (2) “arthroscopy” or “surgery.” The “femoracetabular impingement [Surgery]” subheading in MEDLINE and the “femoroacetabular impingement
[Surgery]” subheading in EMBASE were also searched. The results were uploaded to a bibliographic management database (RefWorks, version 2.0; Bethesda, MD). Data were collected from the included articles by 2 reviewers (M.Y., S.L.). Abstracted data included the following information: title, author, year of publication, location (city, country, continent), sample size, number of male and female patients, mean age, length of follow-up, levels of evidence, type of intervention studied, type of diagnostic imaging used, and outcome measures reported. Descriptive statistics concerning the numbers of randomized controlled trial publications and total sample population studied, sex ratio, type of diagnostic imaging used, reported outcome measures, and level of evidence used were computed by continent. The computer-generated maps were created using Tableau visual data analysis software (Seattle, WA). The cumulative sample sizes studied per city were imported into the mapping software. The software graphically represented the value as a circle at the geographic location of the city, with the area of the circle proportional to the numeric value of cumulative sample size at that city.
Results Our electronic searches yielded 1,411 studies, with 105 studies found to meet the inclusion criteria; these studies were included in the analysis (Fig 1). All 105 included studies were published between 2004 and 2013. A total of 7,880 patients with FAI were managed surgically across all included studies. Most studies investigated arthroscopic intervention (57 studies), followed by open surgical dislocation (34 studies), miniopen approaches (16 studies), combined approaches (8 studies), and periacetabular osteotomy (2 studies). Fifty-two studies (3,629 patients) were performed in North America, 44 studies (3,745 patients) were performed in Europe, 6 studies (394 patients) were performed in Oceania, and 3 studies (49 patients) were performed in Asia. There were no studies found from the continents of South America and Africa (Table 1 and Fig 2). Most studies investigated arthroscopic intervention (57 studies, 5,059 patients), followed by open surgical dislocation (34 studies, 1,437 patients), miniopen approaches (16 studies, 890 patients), combined approaches (8 studies, 254 patients), and periacetabular osteotomy (2 studies, 73 patients) (Table 2). In North America, 73% (2,648 patients) of patients underwent arthroscopic intervention, compared with 11% (407 patients) who underwent surgical dislocation, 10% (372 patients) who underwent miniopen procedures, 7% (253 patients) who underwent combined procedures, and 2% (73) who underwent periacetabular
GLOBAL DISCREPANCIES IN FAI SURGERY
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Fig 1. Summary of the literature search and inclusion/exclusion process.
osteotomy (Fig 3). In Europe, 57% (2,075 patients) of patients underwent arthroscopic intervention, 26% (933 patients) underwent open surgical dislocation, 16% (566 patients) underwent miniopen procedures, and 2% (59 patients) underwent combined procedures. In Oceania, 88% (346 patients) underwent arthroscopic intervention and 12% (46 patients) underwent open surgical dislocation. All patients in studies from Asia (49 patients) underwent surgical hip dislocation. Overall, 91 studies reported the use of radiography and 65 studies reported the use of magnetic resonance imaging (MRI) for diagnosis of FAI. A smaller proportion of studies (25 studies) reported the use of computed tomography (CT) for diagnosis and assessment of FAI. Of the North American studies, 48 studies (92%) reported the use of radiography, whereas 33 studies (63%) reported MRI use, and 15 (29%) reported the use of CT. In Europe, 34 studies (77%) reported the use of radiography, 26 studies (59%) reported the use of MRI, and 5 studies (11%) reported CT use. In Oceania, all 6 studies used radiography, whereas 4 studies (67%) used MRI and CT. In the Asian studies, all 3 studies used radiography, whereas 2 studies (67%) reported MRI use, and one study (33%) reported CT use.
The overall sex ratio of the entire study population was 61:39 male to female patients. The North American population had a sex ratio of 60:40. In Europe, the male to female ratio was 59:41. In Oceania, the sex ratio of male to female patients was 77:23. The Asian population had a sex ratio of 78:22. The most commonly used reported outcome measure in all studies was the Harris Hip Score (HHS), with the modified Harris Hip Score (mHHS) used in 32 studies (30.5%) and the original HHS used in 17 studies (16.2%), Other commonly used reported outcome measures were clinical range of motion, used in 28 studies (26.7%), the Non-Arthritic Hip Score (NAHS), used in 23 studies (21.9%), and the Western Ontario and McMaster University score (WOMAC), used in 21 studies (20%). Other clinical outcome measures used are listed in Table 3. Common radiologic outcomes were the alpha angle, used in 30 studies (28.6%), degenerative changes, reported in 20 studies (19.0%), and head-neck offset, used in 8 studies (7.6%). Other radiologic outcomes are reported in Table 4. Over the years, various measures such as mHHS and hip outcome scores have become popular for outcome analysis in surgical FAI studies (Fig 4).
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Table 1. Geographic Distribution of Surgical Femoroacetabular Impingement Studies Geographic Region North America Canada Mexico United States Europe France Germany Italy Spain Switzerland United Kingdom Oceania Australia New Zealand Asia South Korea Turkey South America e Africa e
Number of Studies 52 5 2 45 44 6 7 1 3 19 8 6 5 1 3 1 2 0 e 0 e
Sample Size Studied (No. of Patients) 3,629 82 124 3,404 3,745 473 248 8 151 1,654 1,211 394 346 48 49 14 35 0 e 0 e
In North America, the most commonly used outcome measures were the mHHS score, used in 21 studies (40%), and the HHS, used in 7 studies (13%). European studies most commonly used WOMAC and NAHSd15 (34.9%) and 14 (32.6%) of studies, respectively. Oceania most commonly used mHHS and NAHS; each was used in 5 studies (83.3%). Asia used
HHS in all 3 studies from the region. Common clinical outcome measures and frequency of use by region are listed in Table 3. Alpha angle was the most commonly used radiographic outcome in all regions. Other common radiologic outcome measures by region are shown in Table 4. Most of the 105 studies located were case series of Level IV evidence (76%), whereas retrospective cohorts (Level III evidence), prospective cohorts (Level II evidence), and randomized controlled trials (Level 1 evidence) were less common (Table 2). Case series made up 75% of North American studies (39 studies), 68.2% of European studies (30 studies), 57.1% of Oceanic studies (4 studies), and 100% of Asian studies (3 studies). Level III evidence constituted 11.5% (6 studies) of the North American cohort, 18.2% (8 studies) of the European cohort, and 14.3% (1 study) of the Oceania cohort but were absent in Asian studies. Level II evidence made up 11.5% (6 studies) of North American studies, 13.6% (6 studies) of European studies, 14.3% (1 study) of studies from Oceania, and was absent in the Asian cohort. Only 2 studies of Level I evidence were founddone from North America and the other from Oceania.
Discussion Key Findings This systematic review evaluated the global diagnostic and treatment trends addressing FAI. We found that most published FAI studies were carried out in Europe
Fig 2. Geographic distribution of surgical studies in femoroacetabular impingement by sample size.
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GLOBAL DISCREPANCIES IN FAI SURGERY Table 2. Global Trends of Surgical Studies in Femoroacetabular Impingement (By Continent) Study Characteristic Studies Total sample size (no. of patients) Surgical intervention (no. of patients undergoing intervention) Arthroscopic Surgical dislocation Miniopen Combined Periacetabular osteotomy Diagnostic imaging (no. of studies used) Radiography MRI CT Most commonly used outcome measures (percentage of studies used) Sex ratio (M:F as ratio of 100) Level of Evidence Level I Level II Level III Level IV
North America 52 (49.5%) 3,629 (46.4%)
Europe 44 (41.9%) 3,745 (47.9%)
Oceania 6 (5.7%) 394 (5.0%)
Asia 3 (2.9%) 49 (0.6%)
South America 0 0
Africa 0 0
2,638 407 324 195 73
(73%) (11%) (9%) (5%) (2%)
2,075 933 372 253
346 (88%) 48 (12%) e e e
e 49 (100%) e e e
e e e e e
e e e e e
48 33 15 mHHS
(92%) (63%) (29%) (40%)
3 (100%) 2 (67%) 1 (33%) mHHS (83%) NAHS (83%) 78:22
e e e e
e e e e
e e e e e e
e e e e e e
60:40 1 6 6 39
(2%) (11.5%) (11.5%) (75%)
(57%) (26%) (10%) (7%) e
34 (77%) 26 (59%) 5 (11%) WOMAC (35%) NAHS (33%) 59:41 0 6 8 30
(0%) (13.6%) (18.2%) (68.2%)
6 4 4 HHS
(100%) (67%) (67%) (100%)
77:23 1 1 1 4
(14.3%) (14.3%) (14.3%) (57.1%)
0 0 0 3
(0%) (0%) (0%) (100%)
NOTE. Data presented as n (%) unless otherwise indicated. CT, computed tomography; HHS, Harris Hip Score; mHHS, modified Harris Hip Score; MRI, magnetic resonance imaging; NAHS, Non-Arthritis Hip Score; WOMAC, Western Ontario and McMaster University score.
and North America, which may result from a number of reasons. First, various factors affect the output of surgical publications, including availability of research resources, research spending, health care infrastructure, population size, and proficiency in the English language.5,6 Many of the countries in which FAI research
Fig 3. Breakdown of patients in surgical femoroacetabular impingement (FAI) studies by surgical technique.
was published rank high in research expenditure per gross domestic product and are English proficient. It has also been postulated that FAI and resultant osteoarthritis may be genetically linked, predisposing particular populations with European ancestry.7 Various FAI cohorts identified a predominance of white patients,
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Table 3. Global Trends of Clinical Outcome Measure Use in Surgical Studies in Femoroacetabular Impingement (By Continent) Clinical Outcome Measure Complications Revisions Conversion to total hip arthroplasty mHHS Range of motion NAHS WOMAC VAS pain scale Satisfaction Impingement sign HHS Return to sport Merle d’Aubigne Hip Outcome Score SF12 Pain Kinematic measurements SF36 Oxford hip score Tegner activity score Dexeus score Return to work UCLA score SUSHI (Super Simple Hip Score) Procedure time Hospital stay Return to activities of daily living Global treatment outcome Rosser quality of life Devane activity scale Length of scar Blood loss Christensen score Return to practice Return to preoperative strength Sports frequency score EQ5D (Euroqol 5 dimensions) Symptom-specific well-being Expectations Hip Sports Activity Scale Level of sports activity Subjective hip value Hip abductor strength
North America 40 (76.9%) 34 (65.4%) 27 (51.9%) 21 (40.4%) 11 (21.2%) 4 (7.7%) 7 (13.5%) 8 (15.4%) 7 (13.5%) 7 (13.5%) 7 (13.5%) 8 (15.4%) 3 (5.8%) 8 (15.4%) 7 (13.5%) 4 (7.7%) 4 (7.7%) 2 (3.8%) e 3 (5.8%) 1 (1.9%) e e 2 (3.8%) e e e e e e e e e e e e e e e e e e e
Europe 27 (62.8%) 23 (53.5%) 15 (34.9%) e 15 (34.9%) 14 (32.6%) 15 (34.9%) 11 (25.6%) 7 (16.3%) 8 (18.6%) 7 (16.3%) 5 (11.6%) 9 (20.9%) 3 (7.0%) 2 (4.7%) 2 (4.7%) e 2 (4.7%) 4 (9.3%) e 2 (4.7%) 3 (7.0%) 3 (7.0%) e 2 (4.7%) 2 (4.7%) 2 (4.7%) 2 (4.7%) 2 (4.7%) 1 (2.3%) 1 (2.3%) 1 (2.3%) 1 (2.3%) 1 (2.3%) 1 (2.3%) 1 (2.3%) 1 (2.3%) 1 (2.3%) 1 (2.3%) 1 (2.3%) 1 (2.3%) 1 (2.3%) 1 (2.3%)
Oceania 5 (83.3%) 5 (83.3%) 3 (50.0%) 5 (83.3%) 1 (16.7%) 5 (83.3%) 1 (16.7%) e 3 (50.0%) 1 (16.7%) e 2 (33.3%) e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e
Asia 3 (100.0%) 2 (66.6%) 1 (33.3%) e 1 (33.3%) e e e 1 (33.3%) 2 (66.6%) 3 (100.0%) e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e
South America e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e
Africa e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e
75 64 46 32 28 23 23 19 18 18 17 15 12 11 9 6 4 4 4 3 3 3 3 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1
Total (71.4%) (61.0%) (43.8%) (30.5%) (26.7%) (21.9%) (21.9%) (18.1%) (17.1%) (17.1%) (16.2%) (14.3%) (11.4%) (10.5%) (8.6%) (5.7%) (3.8%) (3.8%) (3.8%) (2.9%) (2.9%) (2.9%) (2.9%) (1.9%) (1.9%) (1.9%) (1.9%) (1.9%) (1.9%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%)
NOTE. Data presented as n (%). HHS, Harris Hip Score; mHHS, modified Harris Hip Score; NAHS, Non-Arthritis Hip Score; SF12, 12-item short-form survey; SUSHI, Super Simple Hip Score; UCLA, University of California, Los Angeles; VAS, visual analog scale; WOMAC, Western Ontario and McMaster University score.
composing 79% to 88% of the FAI population.8 This ethnic predisposition could explain the increased surgical incidence in regions that have significant populations of European descent and the converse in African and Asian regions. However, the findings of this study also beg the question of whether FAI is a disease of the affluent or a clinical phenomenon seen in patients in developed regions with functional disabilities in sports and other such recreational activities and not a disease entity that is diagnosed and surgically treated in developing nations. Many of the countries where this research is occurring are also places where athletic
participation is quite vibrant, and it has been postulated that FAI may be the result of athletic participation while individuals are young.9 Furthermore, limited health care resources are focused more on acute medical conditions. This geographic discrepancy of FAI research may also reflect the current stage of surgical innovation in FAI. It has been suggested by experts in surgical research that in early stages of innovation, the research landscape primarily consists of case series conducted by opinion leaders, which is similar to the results of this study regarding available FAI literature.10 As surgical management of FAI continues to mature, we anticipate
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GLOBAL DISCREPANCIES IN FAI SURGERY Table 4. Global Trends of Radiographic Outcome Measure Use in Surgical Studies in Femoroacetabular Impingement (By Continent) Radiographic Outcome Measure Alpha angle Degenerative changes Head-neck offset Crossover sign Center-edge angle Caput-collum-diaphyseal angle Tonnis angle Extrusion index Head-neck offset ratio Posterior wall sign Resection depth Resection depth ratio Acetabular depth Signs of avascular necrosis on MRI Articulotrochanteric distance Heymann and Herndon femoral head-neck index Triangular index Acetabular index Ischial spine sign Ischial spine prominence Resection width Acetabular coverage angle
North America 13 (25.0%) 9 (17.3%) 4 (7.7%) 6 (11.5%) 4 (7.7%) 1 (1.9%) 2 (3.8%) 1 (1.9%) 1 (1.9%) 1 (1.9%) e e 1 (1.9%) 1 (1.9%) e e e e e e e
Europe 16 (37.2%) 11 (25.6%) 4 (9.3%) 1 (2.3%) 2 (4.7%) 2 (4.7%) 1 1 1 2 2 2
(2.3%) (2.3%) (2.3%) (4.7%) (4.7%) (4.7%)
1 1 1 1 1 1 1
(2.3%) (2.3%) (2.3%) (2.3%) (2.3%) (2.3%) (2.3%)
Oceania e e e e e e e e e e e e e e e e e e e e e e
Asia 1 (33.3%) e e e e e e e e e e e e e e e e e e e e e
South America e e e e e e e e e e e e e e e e e e e e e e
Africa e e e e e e e e e e e e e e e e e e e e e e
30 20 8 7 6 3 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1
Total (28.6%) (19.0%) (7.6%) (6.7%) (5.7%) (2.9%) (1.9%) (1.9%) (1.9%) (1.9%) (1.9%) (1.9%) (1.9%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%) (1.0%)
NOTE. Data presented as n (%). HOS, hip outcome scores; MDA, Merle d’Aubigne score; MRI, magnetic resonance imaging.
an increase in the presence of methodologically rigorous research such as randomized trials. Arthroscopic interventions for FAI were most common in most continents. Similarly, the pattern of diagnostic imaging use was fairly consistent between regions. Radiographic assessment was most commonly used globally, which is not surprising given its accessibility, relative ease to perform, and low cost. Sex ratios were similar across geographic regions, with an overall male to female ratio of 61:39. These
Fig 4. Clinical outcome measures in femoroacetabular impingement studies by year. (HHS, Harris Hip Score; HOS, hip outcome scores; MDA, Merle d’Aubigne score; mHHS, modified Harris Hip Score; NAHS, Non-Arthritic Hip Score; UCLA, University of California, Los Angeles; WOMAC, Western Ontario and McMaster University score.
results are consistent with previous systematic reviews of the FAI literature, which have also shown a maledominant population.11,12 We also found variability in reported outcome measures in the FAI literature. This echoes the results of a systematic review by Hetaimish et al.,3 which also showed significant variability in reported outcome measures in the FAI literature. Our findings also noted geographic discrepancies in the reporting of outcome measures, with mHHS being used most commonly in North America compared with WOMAC and NAHS in Europe. The findings of this study emphasize the need for consistent outcome assessment and reporting with tools developed and validated to assess nonarthritic hip pain in the young adult. Further, these outcomes tools need to be validated cross-culturally to globally standardize outcome reporting. Future Directions The geographic discrepancy seen in outcome measures used in FAI studies underscores limitations in our ability to assess and compare our surgical results and outcomes. Future directions should include attempts to use a validated and standardized outcome measure in surgical FAI studies that can be applied and used globally. Two outcomes toolsdthe International Hip Outcome Tool (iHOT-33) scale and the Copenhagen Hip and Groin Outcome Score (HAGOS)drecently have been published that fulfill these criteria, yet they were published after the studies reviewed were
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undertaken.13,14 Assessment of the utility of these outcome measures using the Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN) tool has shown promise in new tools such as the International Hip Outcome Tool and HAGOS scales but have ascertained that further study needs to be performed to study the effectiveness of these tools to identify change in longitudinal FAI cohorts.15 Further comparisons should be performed to identify the most effective outcome tool, and, furthermore, researchers worldwide will need to come to a consensus on a standardized measure to be used consistently across the world.
research. We found FAI research globally is predominated by studies of low-level evidence, primarily conducted in North America and Europe, with a lack of outcome measure standardization. Encouragingly, patterns of diagnostic imaging and sex proportions, as well as the predominance of arthroscopic techniques, are consistent across geographic regions. This review shows the potential for globally collaborative highlevel research in FAI and highlights the need for developing reliable validated outcome measures to assess FAI outcomes internationally.
Strengths and Limitations There were several strengths to this systematic review. First, multiple reviewers (M.Y., J.A., S.L.) were involved in the screening of studies and abstraction of data from our literature search. Second, we used a broad-based search strategy resulting in a comprehensive search of multiple databases. We also did not limit our search to English articles and thus improved the breadth of our search and ensured accurate geographic representation in our study. However, some limitations do exist with this review. A small number of the studies that otherwise may have met our inclusion criteria did not have locatable fulltext articles despite an extensive search, and this may have affected the distributions we found in our results. Furthermore, some authors were involved in multiple studies, and despite our attempts to contact the authors, we were unable to confirm if there was any overlap in the patient population between studies. Finally, surgical intervention for FAI may be occurring in Africa or South America, but despite an exhaustive search, results or publications, or both, on this population are pending or unreported. The absence of studies and publications in Africa and South America and the dearth of similar research in Asia highlight the scarcity of information about FAI in these parts of the world. Further research should be performed in these geographic regions to provide foundational information about regional trends in methods of diagnosis and surgical management. Such investigations regarding the pattern of diagnosis could also help identify the reason for the geographic disparity found in our study. Is FAI not as prevalent in certain ethnicities and genotypes? Is FAI a disease of affluence that is infrequent in the developing world, or are there issues surrounding lack of access to imaging, diagnostic tools, and surgical expertise in these areas?
1. Ganz R, Parvizi J, Beck M, Leunig M, Nötzli H, Siebenrock KA. Femoroacetabular impingement: A cause for osteoarthritis of the hip. Clin Orthop Relat Res 2003;417: 112-120. 2. Ayeni OR, Chan K, Al-Asiri J, et al. Sources and quality of literature addressing femoroacetabular impingement. Knee Surg Sports Traumatol Arthrosc 2013;21:415-419. 3. Hetaimish BM, Khan M, Crouch S, et al. Consistency of reported outcomes after arthroscopic management of femoroacetabular impingement. Arthroscopy 2013;29: 780-787. 4. Yeung M, Bhandari M. Uneven global distribution of randomized trials in hip fracture surgery. Acta Orthop 2012;83:328-333. 5. Man JP, Weinkauf JG, Tsang M, Sin DD. Why do some countries publish more than others? An international comparison of research funding, English proficiency and publication output in highly ranked general medical journals. Eur J Epidemiol 2004;19:811-817. 6. Van Rossum M, Bosker B, Pierik E, Verheyen C. Geographic origin of publications in surgical journals. Br J Surg 2007;94:244-247. 7. Hoaglund FT. Primary osteoarthritis of the hip: A genetic disease caused by European genetic variants. J Bone Joint Surg Am 2013;95:463-468. 8. Clohisy JC, Baca G, Beaulé PE, et al. Descriptive epidemiology of femoroacetabular impingement: A North American cohort of patients undergoing surgery. Am J Sports Med 2013;41:1348-1356. 9. Byrd JW. Femoroacetabular impingement in athletes: Current concepts. Am J Sports Med 2014;42:737-751. 10. Barkun J, Aronson J, Feldman L, Maddern G, Strasberg S. Surgical innovation and evaluation 1: Evaluation and stages of surgical innovation. Lancet 2009;374:1089-1096. 11. Clohisy JC, St John LC, Schutz AL. Surgical treatment of femoroacetabular impingement: A systematic review of the literature. Clin Orthop Relat Res 2010;468:555-564. 12. Alradwan H, Philippon MJ, Farrokhyar F, et al. Return to preinjury activity levels after surgical management of femoroacetabular impingement in athletes. Arthroscopy 2012;28:1567-1576. 13. Mohtadi NG, Griffin DR, Pedersen ME, et al. The development and validation of a self-administered quality-oflife outcome measure for young, active patients with
Conclusions This systematic review shows significant geographic discrepancies in the contributions of surgical FAI
References
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