Clinical presentation and disease characteristics of femoroacetabular impingement are sex-dependent

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1 Washington University School of Meicine Digital pen Access Publications 2014 Clinical presentation an isease characteristics of femoroacetabular impingement are sex-epenent Jeffrey J. Nepple Washington University School of Meicine in St. Louis Cassanra N. Riggs Washington University School of Meicine in St. Louis James R. Ross Washington University School of Meicine in St. Louis John C. Clohisy Washington University School of Meicine in St. Louis Follow this an aitional works at: Recommene Citation Nepple, Jeffrey J.; Riggs, Cassanra N.; Ross, James R.; an Clohisy, John C.,,"Clinical presentation an isease characteristics of femoroacetabular impingement are sex-epenent." The Journal of Bone an Joint Surgery.96, (2014). This pen Access Publication is brought to you for free an open access by Digital It has been accepte for inclusion in pen Access Publications by an authorize aministrator of Digital For more information, please contact

2 1683 CPYRIGHT Ó 2014 BY THE JURNAL F BNE AND JINT SURGERY, INCRPRATED Clinical Presentation an Disease Characteristics of Femoroacetabular Impingement Are Sex-Depenent Jeffrey J. Nepple, MD, Cassanra N. Riggs, MD, James R. Ross, MD, an John C. Clohisy, MD Investigation performe at the Department of rthopaeic Surgery, Washington University School of Meicine, St. Louis, Missouri Backgroun: Cam-type femoroacetabular impingement (FAI) is generally escribe as being more common in males, with pincer-type FAI being more common in females. The purpose of this stuy was to etermine the effect of sex on FAI subtype, clinical presentation, raiographic finings, an intraoperative finings in patients with symptomatic FAI. Methos: We compare cohorts of fifty consecutive male an fifty consecutive female patients who were unergoing surgery for symptomatic FAI. Detaile information regaring clinical presentation, raiographic finings, an intraoperative pathology was recore prospectively an analyze. FAI subtype was classifie on the basis of clinical iagnosis an raiographic evaluation. Results: Female patients ha significantly greater isability at presentation, as measure with use of the moifie Harris hip score (mhhs), the Western ntario an McMaster Universities steoarthritis Inex (WMAC), the Hip Disability an steoarthritis utcome Score (HS), an the SF-12 (12-Item Short Form Health Survey) physical function subscore (all p 0.02), espite a significantly lower UCLA (University of California at Los Angeles) activity score (p = 0.03). Female patients ha greater hip motion (flexion an internal rotation an external rotation in 90 of flexion; all p 0.003) an less severe cam-type morphologies (a mean maximum alpha angle of 57.6 compare with 70.8 for males; p < 0.001). Males were significantly more likely to have avance acetabular cartilage lesions (56% of males compare with 24% of females; p = 0.001) an larger labral tears with more posterior extension of these abnormalities (p < 0.02). Males were more likely than females to have mixe-type FAI an thus a component of pincer-type FAI (combine-type FAI) (62% of males compare with 32% of females; p = 0.003). Conclusions: We foun istinct, sex-epenent isease patterns in patients with symptomatic FAI. Females ha more profoun symptomatology an miler morphologic abnormalities, while males ha a higher activity level, larger morphologic abnormalities, more common combine-type FAI morphologies, an more extensive intra-articular isease. Level of Evience: Prognostic Level I. See Instructions for Authors for a complete escription of levels of evience. Peer Review: This article was reviewe by the Eitor-in-Chief an one Deputy Eitor, an it unerwent bline review by two or more outsie experts. The Deputy Eitor reviewe each revision of the article, an it unerwent a final review by the Eitor-in-Chief prior to publication. Final corrections an clarifications occurre uring one or more exchanges between the author(s) an copyeitors. Femoroacetabular impingement (FAI) is increasingly recognize as a cause of hip pain in young, active aults 1,2.FAI results from abnormal, repetitive contact between the femoral hea-neck junction an the acetabular rim as a result of abnormal osseous morphology or supraphysiological motion (from participation in activities requiring excessive hip flexion or internal rotation). This can result in amage to the acetabular chonrolabral junction, resulting in labral injury an/or etachment, as well as ajacent articular cartilage amage. The subtypes of FAI can be classifie as cam, pincer, or combine (cam an pincer). Cam-type FAI results from eformity of the femoral hea-neck junction an results in focal chonrolabral junction amage, incluing labral etachment an variable components of acetabular rim elamination 3. Pincer-type FAI Disclosure: None of the authors receive payments or services, either irectly or inirectly (i.e., via his or her institution), from a thir party in support of any aspect of this work. ne or more of the authors, or his or her institution, has ha a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomeical arena that coul be perceive to influence or have the potential to influence what is written in this work. No author has ha any other relationships, or has engage in any other activities, that coul be perceive to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitte by authors are always provie with the online version of the article. J Bone Joint Surg Am. 2014;96:

3 1684 results from acetabular rim overcoverage as a result of acetabular retroversion, focal anterosuperior overcoverage, or global acetabular overcoverage. Chonrolabral injury in pincer-type FAI can result in labral etachment or ossification from repetitive injury 3. Acetabular rim amage is generally less estructive with pincer-type FAI, with partial-thickness amage confine to the peripheral acetabular rim. The sex of a patient has been significantly associate with raiographic ifferences in FAI eformity, the severity of intraarticular isease, an outcomes 1,2,4-6. Ientifying sex-specific isease patterns is important to improving iagnostic an treatment algorithms. An accurate unerstaning of ifferences in FAI isease patterns between males an females may improve sexepenent iagnostic criteria. Cam-type FAI previously has been escribe as a problem in young males, while pincer-type FAI has been note as most common in mile-age females 1,2,7. Most authors have escribe the combine type of FAI as occurring most frequently 1,2,7-9. The classification of FAI subtype is epenent on both raiographic finings an ynamic intraoperative assessment. Raiographic evaluation is limite by a lack of consensus regaring criteria, which continue to evolve as the raiographic features of FAI are better unerstoo. The authors of several previous stuies have reporte ifferences in FAI eformity an intra-articular pathology between males an females 1,2,4-9. The purpose of this stuy was to comprehensively characterize the effect of sex on FAI subtype an on clinical, raiographic, an intraoperative finings in consecutive cohorts of male an female patients with symptomatic FAI. ur hypothesis was that significant ifferences in the clinical presentation of FAI exist between males an females. Materials an Methos Cohorts of fifty consecutive male an fifty consecutive female patients who ha symptomatic FAI an were unergoing surgical treatment by the senior author (J.C.C.) were prospectively ientifie. Approval for the stuy was obtaine from our institutional review boar. Inclusion criteria inclue: primary surgical treatment of FAI, failure of conservative treatment, an age of less than fifty years, an a Tönnis osteoarthritis grae of 1. Exclusion criteria inclue: acetabular ysplasia, osteonecrosis, prior hip surgery, posttraumatic hip isorer, an resiual peiatric hip isease (slippe capital femoral epiphysis or Legg-Calvé-Perthes isease). For patients who unerwent surgery on both hips uring the stuy perio, one hip was ranomly selecte for inclusion. All patients unerwent surgery between July 2010 an November Surgical treatment inclue hip arthroscopy (89 patients), surgical hip islocation (10 patients), an anteversion periacetabular osteotomy combine with hip arthroscopy (one patient). All proceures provie visualization for complete intraoperative isease classification. The senior surgeon (J.C.C.) prospectively recore etaile clinical finings an intraoperative pathology 10. Clinical ata inclue age, FAI subtype, boy mass inex (BMI), uration of symptoms, location of pain, an history of contralateral surgery. The clinical iagnosis an subtype of FAI were etermine by the senior author on the basis of preoperative imaging an intraoperative finings. Preoperative imaging inclue raiographs an magnetic resonance imaging (MRI) as well as, in some cases, compute tomography (CT). MR arthrograms were obtaine in all cases but not inclue in the current stuy because of the variability in the protocols use between patients. FAI subtype was classifie as cam-type, pincer-type, or combine-type (cam an pincer). Baseline clinical scores were recore. Measures inclue the moifie Harris hip score (mhhs), the UCLA (University of California at Los Angeles) activity score, the Western ntario an McMaster Universities steoarthritis Inex (WMAC), the Hip Disability an steoarthritis utcome Score (HS) 11, an the SF-12 (12-Item Short Form Health Survey). Higher WMAC scores inicate more isability, while higher scores of all other outcome instruments inicate better function/less symptoms. A UCLA score of 9 was efine as inicating high-level activity (participation in impact sports) 12. The total WMAC score (0 to 96) was calculate by summing subscores for pain (0 to 20), stiffness (0 to 8), an physical function (0 to 68). The total HS was calculate as the average of five subscores (each 0 to 100): pain, symptoms, activities of aily living, sports, an quality of life. The SF-12 omains of physical an emotional function were also recore. Pain location was characterize as anterior groin, lateral hip, posterior hip, or anterior thigh. Detaile measurements of hip motion were performe as previously escribe 13 by a single examiner (the senior author) an inclue hip flexion, internal rotation in 90 of flexion (IRF), external rotation in 90 of flexion (ERF), internal rotation with the hip in extension (IRE), an external rotation with the hip in extension (ERE) (performe with the patient supine an with the position of the patella as reference) as well as hip abuction an hip auction. The en point for motion testing was etermine as the point at which the pelvis began to move. Raiographic analysis inclue an evaluation of anteroposterior pelvic, frog-leg lateral, 45 Dunn lateral, an false-profile views. All raiographs were mae accoring to previously publishe stanarize techniques 14. Raiographs were analyze with use of computer-assiste raiographic-measurement software (HipMorphometry) 15,16 by two of the authors, who were bline to clinical finings. ne reaer (J.J.N.) analyze the anteroposterior pelvic an false-profile raiographs, an the secon reaer (J.R.R.) analyze the frog-leg an 45 Dunn lateral raiographs. The raiographic evaluation inclue measurements of the lateral center-ege angle, the acetabular inclination, the anterior center-ege angle, the neck-shaft angle, the moifie proximal femoral angle, the crossover sign (an crossover sign istance), the posterior wall sign (an istance), the prominent ischial spine sign, the alpha angle (frog-leg, Dunn, an anteroposterior pelvic views), an hea-neck offset ratio (frog-leg an Dunn views). Parameters of acetabular version (crossover sign, posterior wall sign, an prominent ischial spine sign) were assesse only for raiographs showing appropriate pelvic tilt (a sacrococcygeal istance of 25 to 50 mm for males an 30 to 65 mm for females) 17. Similarly, classification of the raiographic FAI subtype was assesse only for raiographs showing appropriate pelvic tilt. Appropriate pelvic tilt was present in 68% of males an 64% of females. Raiographic evience of cam-type morphology was efine as a maximum alpha angle of >50 or a minimum hea-neck offset ratio of 0.17 on any view. Raiographic evience of pincer-type morphology was efine as a positive crossover sign with a crossover sign istance of >10 mm, a lateral centerege angle of >40, an/or an acetabular inclination of <0. Raiographic FAI subtype was aitionally classifie as isolate cam, isolate pincer, or combine FAI. The interobserver reliability of raiographic analysis of the young ault has been previously reporte 18-20, incluing for the reaers in our stuy (alpha angle, 0.94; hea-neck offset ratio, 0.97; crossover sign, 0.86; lateral center-ege angle, 0.99; an anterior center-ege angle, 0.99) 16,21,22. Intraoperative proceures, incluing labral ebriement, labral repair, femoral hea-neck junction osteoplasty, acetabular rim trimming, acetabular microfracture, an psoas tenon lengthening, were recore. Intraoperative pathology of the acetabular labrum, acetabular cartilage, femoral hea cartilage, an ligamentum teres was also recore. Acetabular chonromalacia was classifie as 1 (normal), 2 (malacia), 3 (eboning), 4 (cleavage), or 5 (efect), accoring to the system of Beck et al. 3 : Labral pathology was also classifie accoring to the system of Beck et al. 3 : 1 (normal), 2 (egeneration), 3 (full-thickness tear), 4 (etachment), or 5 (ossification). The location an the size of lesions were prospectively recore. The location of acetabular rim chonrolabral pathology was recore with use of stanar clock-face nomenclature (posterior, 9:00; superior, 12:00; an anterior, 3:00 on right an left hip), as were acetabular ivisions (posterior, <10:30; superolateral, 10:30 to 1:30; an anterior, >1:30).

4 1685 TABLE I Preoperative Patient-Reporte utcome an Activity Scores by Sex* Female Male Measure Mean (SD) Mean (SD) Mean Difference P Value mhhs 54.4 (14.8) 63.7 (16.6) UCLA activity score 6.8 (2.7) 8.1 (2.4) WMAC 41.2 (21.1) 31.6 (23.2) Pain 9.6 (4.3) 6.2 (3.7) 3.4 <0.001 Stiffness 4.2 (1.7) 2.9 (2.0) Physical function 27.4 (16.1) 22.5 (20.6) HS 45.8 (17.4) 55.5 (19.3) Pain 49.3 (19.5) 62.3 (18.0) Symptoms 49.0 (19.1) 61.5 (22.5) Activities of aily living 60.9 (21.6) 71.9 (20.6) Sports 40.5 (24.0) 49.1 (26.1) Quality of life 29.2 (16.9) 32.6 (20.9) SF-12 Physical function 35.5 (10.7) 41.0 (10.3) Emotional function 54.7 (8.2) 49.3 (11.6) *SD = stanar eviation. Lengths were stanarize such that 1 cm was equivalent to one hour on the clock-face. We performe statistical comparisons of the female an male cohorts with use of the chi-square test or Fisher exact test for categorical variables. The normality of continuous variables was teste with use of the Kolmogorov- Smirnov test an emonstrate lack of normality of the ata. The Mann- Whitney U test was utilize for comparisons of continuous variables. P values of <0.05 were consiere significant. Source of Funing Funing support for ancillary research personnel was provie by the Curing Hip Disease Fun. Results Clinical Finings The mean age of the female cohort was 31.4 years (range, sixteen to forty-nine years), an the mean age of the male cohort was 28.7 years (range, fourteen to forty-nine years) (p = 0.180). Anterior groin pain was present in 86% of the females compare with 94% of the males (p = 0.182). Pain beyon the anterior groin was significantly more common in females (58% compare with 32%; p = 0.009) an inclue lateral trochanteric pain (in 19% of females compare with 10% of males; p = 0.047). No significant TABLE II Hip Range of Motion by Sex* Female Male Range-of-Motion Measurement Mean Difference Mean (SD) Mean (SD) P Value Flexion (5.6 ) 94.4 (4.5 ) IRF (9.4 ) 6.9 (8.0 ) <0.001 ERF (15.3 ) 27.1 (12.6 ) <0.001 Total range of motion (IRF 1 ERF) (17.6 ) 34.0 (15.5 ) <0.001 IRE (6.6 ) 8.1 (7.4 ) <0.001 ERE (16.3 ) 28.1 (9.0 ) Abuction (9.1 ) 34.6 (8.9 ) Auction (4.7 ) 12.6 (5.1 ) *SD = stanar eviation.

5 1686 TABLE III Summary of Raiographic Finings by Sex* Female Male P Value Pincer eformity 47% 56% CS >10 mm 28% 47% LCEA >40 an/or AI <0 25% 21% Cam eformity 88% 100% Alpha angle (max.) <0.001 <50 30% 6% % 22% % 22% % 18% % 24% >90 0% 8% Anteroposterior pelvic <0.001 Dunn <0.001 Frog-leg <0.001 Hea-neck offset ratio (min.) <0.001 > % 4% % 48% < % 48% *Values are presente as the percentage of the group or as the mean. CS = crossover sign, LCEA = lateral center-ege angle, an AI = acetabular inclination. As assesse on raiographs with appropriate pelvic tilt. Maximum alpha angle of >50 or minimum hea-neck offset ratio of ifferences in terms of uration of symptoms, BMI, or history of contralateral surgery were present between males an females. Mean baseline clinical scores of the mhhs, WMAC, HS, an SF-12, which are shown in Table I, inicate significantly more substantial symptomatology an functional limitation in females compare with males. The mean preoperative mhhs was significantly lower for females than for males (54.4 compare with 63.7; p = 0.004). An mhhs of <50 was reporte for 38% of females compare with 18% of males (p = 0.095). An mhhs of >70 was reporte for 38% of males compare with 12% of females (p = 0.003). A UCLA score of 9 was reporte for 62.5% of males compare with 36% of females (p = 0.009). Physical function as measure with the SF-12 was significantly greater for males (p = 0.011), whereas emotional function was significantly greater for females (p = 0.017). n physical examination, females emonstrate significantly greater hip motion in terms of flexion, IRF, ERF, IRE, an auction (Table II). An IRF measurement of <10 was note for 66% of males compare with 12% of females (p < 0.001) (88% of males compare with 58% of females ha an IRF measurement of <20 ; p= 0.002). Thirty-eight percent of males an no females ha an IRF of 0. AnERF measurement of >45 wasseenin30%offemalescompare with 6% of males (p = 0.002). Raiographic Finings Raiographic evience of cam-type morphology (a maximum alpha angle of >50 or a minimum hea-neck offset ratio of 0.17) was present for all of the males an 88% of the females (p = 0.027). Raiographic evience of pincer-type morphology (a crossover-sign istance of >10 mm, a lateral center-ege angle of >40, an/or an acetabular inclination of <0 ) was present for a similar proportion of females an males (47% of females compare with 56% of males; p = 0.464) (Table III). The maximum alpha angle was significantly greater in males (mean, 70.8 ) than in females (mean, 57.6 ) (p < 0.001) (Table III). A maximum alpha angle of >70 was evient in 50% of males compare with 16% of females (p < 0.001). Mean alpha angles were significantly greater for males for the anteroposterior pelvic, Dunn, an frogleg lateral views (all p < 0.001, Table III). The largest ifference between males an females (15.9 ) was seen on the anteroposterior pelvic raiograph, with an alpha angle of >50 present on this view for 72% of males compare with 28% of females (p < 0.001). Males ha a significantly lower femoral neck-shaft angle an moifie proximal femoral angle an were more likely to have a positive posterior wall sign (Table IV). No significant ifferences were seen in terms of the presence of borerline acetabular ysplasia (a lateral center-ege angle of 20 to 25 or an anterior center-ege angle of 20 to 25 ). Intraoperative Finings Labral pathology was present in all hips, an the characteristics of labral pathology were similar between male an females (Table V). Labral repair/refixation was performe in 76% of both males an females, an selective labral ebriement was performe in the remaining 24%. Among hips with labral TABLE IV ther Raiographic Finings by Sex* Female Male P Value LCEA ACEA AI Neck-shaft angle MPFA SC vertical istance (mm) Appropriate pelvic tilt 64% 68% Posterior wall istance (mm) <0.001 Posterior wall sign (<0 mm) 56% 85% Prominent ischial spine sign 47% 50% *Values are presente as the mean or as the percentage of the group. LCEA = lateral center-ege angle, ACEA= anterior centerege angle, AI = acetabular inclination, MPFA = moifie proximal femoral angle, an SC = sacrococcygeal joint. Relative to the superior pubic symphysis. Define as an SC istance of 30 to 65 mm for females an 25 to 50 mm for males. Posterior wall meial (2) an lateral (1) to femoral hea center.

6 1687 TABLE V Intraoperative Finings by Sex* Female Male P Value Beck Acetabular Cartilage Classification 1 (normal) 6% 0% (malacia) 10% 18% (eboning) 60% 26% (cleavage) 20% 42% (efect) 4% 14% Avance acetabular 24% 56% cartilage isease (grae 4-5) Size of chonral lesion, any grae (mm 2 ) Posterior extension (to 10:30, grae 4-5) 0% 14% Beck Labral Classification 1 (normal) 0% 0% NA 2 (egeneration) 10% 12% (full-thickness tear) 0% 0% NA 4 (etachment) 82% 82% (ossification) 8% 6% 1.0 Detachment length (mm) Posterior extension of etachment (to 10:30) 5% 24% *Values are presente as the percentage of the group or as the mean. NA = not applicable. Fisher exact test. TABLE VI Summary of Raiographic an Clinical Classification of FAI Subtype by Sex Raiographic* Clinical FAI Subtype Female Male Female Male Isolate cam (femoral base) Combine cam-pincer Isolate pincer (acetabular base) 47% 44% 68% 38% 41% 56% 32% 62% 6% 0% 0% 0% *As assesse on raiographs with appropriate pelvic tilt. 6% ha no raiographic eformity. etachment, etachment length was significantly greater for males than for females (mean, 28.4 mm compare with 22.1 mm; p = 0.013). Posterior extension of the labral etachment (to 10:30) wasmorecommoninmalesthaninfemales(24%compare with 5%; p = 0.012). Acetabular cartilage pathology was note in all males an in all but three females. Males were more likely than females to have acetabular cartilage cleavage lesions (42% compare with 20%; p = 0.017), while females were more likely than males to have eboning lesions (60% compare with 26%; p = 0.001) (Table V). Females were significantly more likely to have early cartilage changes (malacia or eboning) compare with males (70% compare with 44%; p = 0.009), while males were significantly more likely to have avance cartilage changes (cleavage or efect) compare with females (56% compare with 24%; p = 0.001). The total area of abnormal cartilage an the posterior extension on the acetabular rim (to 10:30) were greater in males (Table V). FAI Subtype The clinical an raiographic iagnosis of FAI subtype by sex is summarize in Table VI. Clinical evience of isolate cam-type or combine-type FAI was seen among all patients (no cases of isolate pincer-type FAI). A component of pincer-type FAI (combine-type FAI) was present in 32% of females compare with62%ofmales(p= 0.003). By raiographic iagnosis alone, all males ha a component of cam-type FAI, with 56% also having a component of pincer-type FAI. Among females, 47% ha isolate cam-type, 41% combine-type, an 6% isolate pincer-type FAI (6% with normal morphology/ functional FAI). A component of pincer-type raiographic FAI was present in 56% of males an 41% of females (p = 0.464). Discussion The iagnosis of FAI can be challenging because of the iversity of the affecte patient population an the wie spectrum of isease patterns encountere. Previous stuies have suggeste that certain isease patterns may be sex-specific 1,2,4,10,23, yet there is a paucity of comprehensive ata comparing FAI isease characteristics in males an females. Unerstaning ifferences between the sexes in the presentation of FAI is important for establishing accurate iagnostic algorithms an for treatment ecision-making. We emonstrate significant ifferences between males an females in terms of FAI subtype, clinical presentation, raiographic finings, an intraoperative pathology. The clinician shoul recognize that female patients with FAI present with significantly more isability, espite generally having less severe eformities an less intra-articular isease. Also, female patients with symptomatic FAI emonstrate miler femoral hea-neck offset eformities, with only 34% (compare with 72% of males) having a maximum alpha angle of >60. Aitionally, internal rotation in flexion was greater in females, with only 12% (compare with 66% of males) showing <10. These ata inicate that iagnostic criteria for males an females are ifferent. Several previous stuies have suggeste that females with FAI have lower clinical scores than males at presentation 4,23. Hetsroni et al. 4 reporte a lower mhhs for females at presentation (63.8 compare with 72.5 for males). Impellizzeri et al. 23 foun that females ha a significantly higher WMAC score (39.4 compare with 25.0), inicating more isability at presentation. In the current stuy, we emonstrate significant ifferences between sexes in terms of mhhs (a mean of 54.4 for females compare with 63.7 for males) an WMAC score (a mean of

7 for females compare with 31.6 for males). The magnitue of these ifferences is greater than the minimal clinically important ifference (MCID) previously reporte for these scores (HHS, 7 to 9 points; WMAC, 4 to 5 points/12% of baseline) 24.Aitionally, we foun significantly lower levels of activity among females (a mean UCLA score of 6.8 for females compare with 8.1 for males). Significantly lower WMAC subscores (pain, stiffness, an physical function), higher HS subscores (pain, symptoms, an activities of aily living), an higher scores for the SF-12 physical function component were also note for males. Recent investigations have suggeste a link between athletic activity uring aolescence an the evelopment of the cam morphology Several previous stuies have suggeste that females with FAI have more subtle abnormalities than males 4,8, Hetsroni et al. 4 foun that females ha significantly smaller alpha angles (a mean of 47.8 compare with 63.6 ) on reformatte axial oblique CT images. However, isolate measurement of the alpha angle at the anterior hea-neck junction on axial images unerestimates the cam-type eformity, which is generally maximal at the anterosuperior hea-neck junction 15, The stuy also note significantly greater acetabular an femoral anteversion in females. Similarly, Beaulé etal. 28, analyzing a group of thirty symptomatic patients with FAI, foun smaller alpha angles in females (a mean of 58.7 compare with 73.3 ). A similar ifference in femoral an acetabular anatomy between males an females has been reporte in asymptomatic populations In the current stuy, on the basis of multiple raiographic views, we foun a mean maximum alpha angle of 57.6 in females an 70.8 in males. Aitionally, the mean minimum hea-neck offset ratio was significantly greater for females (0.16) than for males (0.14). Males were significantly more likely to have large cam morphologies. The largest ifference (15.9 ) between the alpha angle for males an that for females was note in the lateral extension of the cam lesion visualize on the anteroposterior pelvic view. This inicates that cam eformities in males may exten more lateral/posterolateral an can be less accessible to surgical correction, specifically with arthroscopic techniques. Previous stuies have generally escribe cam-type FAI to be more common in males an pincer-type FAI more common in females 1,2,7. The presence of coxa profuna (acetabular fossa touching or meial to the ilioischial line) was previously reporte to be inicative of pincer-type FAI, but this association has recently fallen out of favor because of the high prevalence of coxa profuna in asymptomatic patients an hips with acetabular ysplasia 22,40,41. When consiere in isolation as an inicator of pincer-type FAI, coxa profuna results in over-classification of the pincer-type or combine-type FAI subtype. The current stuy foun cam-type morphology to be present in the majority (88% to 100%) of both males an females, on the basis of both raiographic an clinical assessments (Table VI). A component of pincer-type FAI was more common in males than in females by clinical or raiographic iagnosis. This may be ue to the exclusion of coxa profuna as a parameter of FAI (or the exclusion of raiographs with abnormal pelvic tilt in raiographic iagnosis). Similar to our finings, Hetsroni et al. 4 foun that males were more likely to unergo pincer resection for pincer-type eformity (89% compare with 64%). They also reporte smaller alpha angles an increase acetabular an femoral anteversion in females with FAI compare with males. The current stuy emonstrate significantly higher rates of avance acetabular cartilage isease (cleavage lesions or efects) an larger labral lesions in males. These finings are consistent with a previous investigation emonstrating more severe intraarticular isease finings in males, inepenent of the severity of cam lesion measure by the alpha angle 6. There were several limitations of the current stuy. The patient population in the stuy was heavily reliant on the patient population of the practice of the senior author an the clinical iagnosis of FAI. The senior author has substantial experience in the treatment of pre-arthritic hip isease, incluing FAI, hip ysplasia, an resiual peiatric eformities, an we believe that the stuy cohort was representative of the spectrum of symptomatic FAI patients. Criteria for raiographic iagnosis of cam an pincer morphologies are somewhat controversial, with various recommene iagnostic threshols. Much of the controversy results from the fact that these eformities are not uncommon in asymptomatic iniviuals that may never experience hip symptoms. n the other han, borerline or very mil morphologic abnormalities may be symptomatic ue to extreme activity profiles. In aition to presenting ata base on threshol values utilize in our stuy, we also present etaile ata on associate continuous variables to allow appropriate interpretation. Finally, while raiographic analysis in our stuy was thorough, it i not inclue ata on acetabular an femoral version base on three-imensional imaging, as these stuies were not routinely obtaine in the stuy cohort. However, increase acetabular an femoral anteversion has previously been emonstrate in females compare with males 4. In summary, we emonstrate istinct ifferences in the overall FAI isease presentation between males an females that may ai clinicians in ientifying typical an atypical FAI presentations by sex an in making iagnostic an treatment ecisions. Treatment ecisions regaring pincer-type morphologies shoul be base on clear raiographic evience, as the presence of pincer-type FAI may not follow previously reporte patterns by sex. Miler FAI eformities in females shoul be assesse carefully, as they may still contribute to FAI associate with activities requiring increase amounts of hip flexion an rotation. n Jeffrey J. Nepple, MD Cassanra N. Riggs, MD James R. Ross, MD John C. Clohisy, MD Department of rthopaeic Surgery, Washington University School of Meicine, ne Barnes-Jewish Hospital Plaza, Campus Box 8233, St. Louis, M aress for J.J. Nepple: nepplej@wuosis.wustl.eu

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