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Femoroacetabular impingement (FAI), a recently described hip condition in adolescents and young adults, results from abnormal physical contact between the proximal femur and the acetabulum.1 FAI is usually characterized by the site of the predominant morphologic abnormality—proximal femur (cam-type FAI), acetabulum (pincer-type FAI), or both (mixed impingement). Cam-type FAI is typified by the aspherical extension of the articular surface at the anterosuperior head–neck junction of the proximal femur with loss of the normal offset. With hip motion, especially in the maximal ranges of flexion and internal rotation, the aspherical proximal femur repeatedly contacts the anterosuperior acetabulum, damaging the chondrolabral junction and ultimately the labrum itself. In pincer-type impingement, femoral head overcoverage caused by acetabular retroversion and/or coxa profunda directly damages the anterior labrum when the acetabular rim contacts the proximal femur during physiologic motion. “Contrecoup” injury of the posterior-inferior acetabular cartilage may also occur. Over time, recurrent microtrauma to the acetabular cartilage and/or labrum may lead to degenerative changes of the hip and ultimately to premature osteoarthritis.1,2
Patients with FAI typically present with groin pain that may be activity-related or that may occur with prolonged sitting with the hip in a flexed position. Physical examination findings suggestive of FAI include decreased passive internal hip rotation and reproducible pain with adduction and internal rotation of the flexed hip—the impingement sign, or the flexion, adduction, and internal rotation (FADIR) test.3 Diagnostic imaging evaluation initially includes radiographs of the pelvis and hips. These radiographs may show a “pistol-grip” deformity and/or decreased head–neck offset (as determined by increased alpha angle) in the setting of cam-type impingement (Figure 1).4 Pincer-type impingement may be associated with a crossover sign, coxa profunda, and an increased center-edge angle (CEA). Advanced imaging studies, such as computed tomography (CT), magnetic resonance imaging (MRI) arthrogram, and delayed gadolinium-enhanced MRI of cartilage (dGEMRIC), are commonly used to better delineate bony deformity and concomitant injuries of the labrum and cartilage (Figure 2).
Treatment for FAI often consists initially of activity modification, use of anti-inflammatory medications, and physical therapy. Intra-articular corticosteroid injections may be used both diagnostically and therapeutically. When nonsurgical measures fail to adequately relieve symptoms, surgery may be warranted. Whether performed open or arthroscopically, surgery is directed first at correcting the underlying osseous abnormality—performing an osteoplasty of the proximal femur to remove the cam lesion, performing an acetabular osteoplasty (“rim-trimming”) to address a focal pincer lesion, and/or performing a periacetabular osteotomy to decrease global acetabular overcoverage (Figure 3).5
Sex-Based Differences in FAI Incidence
Traditionally, it was thought that cam-type impingement occurred predominantly in young, athletic males, whereas pincer-type impingement resulting from acetabular overcoverage occurred primarily in females during their fourth decade. However, our understanding of the sex-based differences in the incidence and presentation of FAI has evolved, and it is now clear that the interplay of sex, radiographic signs of impingement, and development of symptoms requiring treatment is more complex.
In recent large population-based studies, investigators have attempted to better characterize the sex-based differences in the incidence of osseous FAI deformity. Gosvig and colleagues2 examined radiographic and questionnaire outcomes of 3620 patients (age range, 21-90 years) and found that males were more likely than females to have a pistol-grip deformity of the hip (19.6% vs 5.2%); that deep acetabular sockets were common in both sexes (15.2% vs 19.4%); and that the presence of pistol-grip deformity or deep socket was significantly associated with development of osteoarthritis, independent of sex.
In a study of 2081 asymptomatic patients (mean age, 18.6 years), Laborie and colleagues4 reported similar radiographic findings. Males were significantly more likely than females to have a cam-type deformity, as evidenced by pistol-grip deformity, focal prominence of the femoral neck, and/or flattening of the lateral aspect of the femoral head. Males were also more likely than females to have a pincer deformity, though radiographic signs of pincer deformity—a crossover sign, excessive acetabular coverage (defined by increased CEA), and a posterior wall sign—were common in both sexes, occurring in 16.6% of females and 34.3% of males. Bilateral findings of FAI-associated deformity were also more common in males than in females, both for cam-type deformity (24.7% vs 6.3%) and pincer-type deformity (21.7% vs 9.7%).
Sex-Based Differences in FAI Presentation
In males and females, the clinical presentation of FAI is similar—insidious onset of deep groin pain, often exacerbated with activity, and physical examination findings of decreased hip motion (particularly internal rotation) and a positive impingement test.3 Nevertheless, the sexes’ clinical presentation differs in several ways. Specifically, in a study using 3-dimensional CT to assess bony deformity in both symptomatic and asymptomatic patients, Beaulé and colleagues6 reported that alpha angles were significantly higher in symptomatic males than in symptomatic females (73.3° vs 58.7°). Hetsroni and colleagues7 recently reported similar results in a study of 217 symptomatic young adults treated arthroscopically for hip pain. Preoperative CT showed that alpha angles were significantly larger in males than in females (63.6° vs 47.8°). The authors postulated that females may be more likely to be symptomatic in the setting of smaller cam lesions because of the increased peak hip flexion and frontal plane motion commonly demonstrated by females during drop landings in sport. The authors further hypothesized that sex differences in muscle mass (which contributes to dynamic hip stability) and ligamentous laxity (a component of static hip stability) may result in larger physiologic ranges of motion for many females. As a result, bony impingement may occur in the setting of smaller anatomical lesions in females. The authors further noted that, compared with their male counterparts, females being treated for symptomatic FAI had significantly more femoral and acetabular anteversion.
Another male–female presentation difference involves symptom bilaterality. Specifically, males are significantly more likely than females to have symptomatic FAI involving both hips. In a recent study of 646 patients who underwent hip arthroscopy for symptomatic FAI during a 2-year period, Klingenstein and colleagues8 found that females constituted 48.2% of unilateral arthroscopy patients but only 34.8% of bilateral arthroscopy patients. The odds ratio of males treated for both hips, compared with females, was 1.7 (95% confidence interval, 1.16–2.54).
Last, it has been reported that, on clinical presentation, hip function scores are significantly lower in females than in males. In a recent study of 612 cases of symptomatic FAI treated with hip arthroscopy, Malviya and colleagues9 found that females had significantly lower quality-of-life scores both before and after surgery. Hetsroni and colleagues7 reported similar findings, with females having significantly lower preoperative modified Harris Hip Scores and lower Hip Outcome Scores in the domains of Activities of Daily Living and Sports.
Sex-Based Differences in FAI Treatment
and Outcomes
Surgical treatment of FAI is focused on identifying the source of hip pain and dysfunction—be it osseous lesion, labral tearing, chondral injury, or iliopsoas tendonitis—and treating it accordingly, regardless of sex. Most studies of this approach find consistent improvement in the short-term and midterm outcome scores for a majority of patients. However, relatively few studies have focused specifically on sex in determining the percentage of patients who require surgical treatment, in deciding the type of surgery that should be performed, or in measuring surgical outcomes in patients with symptomatic FAI.
In their review of 23 studies of FAI surgery, Ng and colleagues10 found that, of 970 patients, 608 (62.7%) were male and 362 (37.3%) were female. Similarly higher rates for males were previously published.5,11 More recently, Clohisy and colleagues12 reported on the descriptive epidemiology of patients having surgery for FAI at 8 different medical centers in North America. Fifty-five percent of the hips surgically treated for symptomatic FAI were females’. The authors speculated that this unexpectedly high rate could have resulted from US and Canadian female athletes’ increasingly higher level of sports participation. The results of this study, one of the largest examining the rate of surgery for males and females with FAI, suggest that females are more likely to have surgery for symptomatic FAI despite being less likely to have radiographic evidence of impingement. Our understanding of this phenomenon continues to advance.
In a recent prospective study, Krych and colleagues13 evaluated the clinical outcomes of FAI surgeries (labral débridement, labral repair) in an all-female patient cohort. Female patients with symptomatic FAI were randomized to undergo either labral débridement or labral repair. There were clinical improvements in both groups, but, compared with labral débridement patients, labral repair patients had more significantly improved Hip Outcome Scores in the domains of Activities of Daily Living and Sports, as well as better subjective outcomes. Although the study did not compare female patients with male patients, it does provide evidence that female patients specifically may benefit more from labral repair than from labral débridement alone.
With respect to different surgical treatments for male and female patients, Hetsroni and colleagues7 introduced the idea of sex-specific treatment when they noted more hip anteversion in their study’s female patients than in its male patients. They suggested that, because the anterosuperior acetabulum is subjected to a high amount of stress during weight-bearing and gait, this area in females with suspected pincer lesions should be rim-trimmed judiciously to avoid increasing the stress and perhaps even hastening the development of degenerative disease. Last, though several authors have noted that hip function scores are lower in females than in males on presentation, it has also been reported that females demonstrate more improvement in functional scores after surgery.9 This may be important information to discuss during preoperative counseling about expected goals and outcomes.
Conclusion
Femoroacetabular impingement is a common clinical entity that affects both males and females. However, sexual dimorphism in FAI incidence, presentation, treatment, and outcomes has recently been described in the literature (Table). Being aware of these sex-based differences and tailoring patient evaluation and management accordingly will likely result in optimal outcomes for each person who presents with symptomatic FAI.
1. Ganz R, Parvizi J, Beck M, Leunig M, Notzli H, Siebenrock KA. Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop. 2003;(417):112-120.
2. Gosvig KK, Jacobsen S, Sonne-Holm S, Palm H, Troelsen A. Prevalence of malformations of the hip joint and their relationship to sex, groin pain, and risk of osteoarthritis: a population-based survey. J Bone Joint Surg Am. 2010;92(5):1162-1169.
3. Philippon MJ, Maxwell RB, Johnston TL, Schenker M, Briggs KK. Clinical presentation of femoroacetabular impingement. Knee Surg Sports Traumatol Arthrosc. 2007;15(8):1041-1047.
4. Laborie LB, Lehmann TG, Engesaeter IO, Eastwood DM, Engesaeter LB, Rosendahl K. Prevalence of radiographic findings thought to be associated with femoroacetabular impingement in a population-based cohort of 2081 healthy young adults. Radiology. 2011;260(2):494-502.
5. Clohisy JC, St John LC, Schutz AL. Surgical treatment of femoroacetabular impingement: a systematic review of the literature. Clin Orthop. 2010;468(2):555-564.
6. Beaulé PE, Zaragoza E, Motamedi K, Copelan N, Dorey FJ. Three-dimensional computed tomography of the hip in the assessment of femoroacetabular impingement. J Orthop Res. 2005;23(6):1286-1292.
7. Hetsroni I, Dela Torre K, Duke G, Lyman S, Kelly BT. Sex differences of hip morphology in young adults with hip pain and labral tears. Arthroscopy. 2013;29(1):54-63.
8. Klingenstein GG, Zbeda RM, Bedi A, Magennis E, Kelly BT. Prevalence and preoperative demographic and radiographic predictors of bilateral femoroacetabular impingement. Am J Sports Med. 2013;41(4):762-768.
9. Malviya A, Stafford GH, Villar RN. Impact of arthroscopy of the hip for femoroacetabular impingement on quality of life at a mean follow-up of 3.2 years. J Bone Joint Surg Br. 2012;94(4):466-470.
10. Ng VY, Arora N, Best TM, Pan X, Ellis TJ. Efficacy of surgery for femoroacetabular impingement: a systematic review. Am J Sports Med. 2010;38(11):2337-2345.
11. Matsuda DK, Carlisle JC, Arthurs SC, Wierks CH, Philippon MJ. Comparative systematic review of the open dislocation, mini-open, and arthroscopic surgeries for femoroacetabular impingement. Arthroscopy. 2011;27(2):252-269.
12. Clohisy JC, Baca G, Beaule PE, et al. Descriptive epidemiology of femoroacetabular impingement: a North American cohort of patients undergoing surgery. Am J Sports Med. 2013;41(6):1348-1356.
13. Krych AJ, Thompson M, Knutson Z, Scoon J, Coleman SH. Arthroscopic labral repair versus selective labral debridement in female patients with femoroacetabular impingement: a prospective randomized study. Arthroscopy. 2013;29(1):46-53.
Femoroacetabular impingement (FAI), a recently described hip condition in adolescents and young adults, results from abnormal physical contact between the proximal femur and the acetabulum.1 FAI is usually characterized by the site of the predominant morphologic abnormality—proximal femur (cam-type FAI), acetabulum (pincer-type FAI), or both (mixed impingement). Cam-type FAI is typified by the aspherical extension of the articular surface at the anterosuperior head–neck junction of the proximal femur with loss of the normal offset. With hip motion, especially in the maximal ranges of flexion and internal rotation, the aspherical proximal femur repeatedly contacts the anterosuperior acetabulum, damaging the chondrolabral junction and ultimately the labrum itself. In pincer-type impingement, femoral head overcoverage caused by acetabular retroversion and/or coxa profunda directly damages the anterior labrum when the acetabular rim contacts the proximal femur during physiologic motion. “Contrecoup” injury of the posterior-inferior acetabular cartilage may also occur. Over time, recurrent microtrauma to the acetabular cartilage and/or labrum may lead to degenerative changes of the hip and ultimately to premature osteoarthritis.1,2
Patients with FAI typically present with groin pain that may be activity-related or that may occur with prolonged sitting with the hip in a flexed position. Physical examination findings suggestive of FAI include decreased passive internal hip rotation and reproducible pain with adduction and internal rotation of the flexed hip—the impingement sign, or the flexion, adduction, and internal rotation (FADIR) test.3 Diagnostic imaging evaluation initially includes radiographs of the pelvis and hips. These radiographs may show a “pistol-grip” deformity and/or decreased head–neck offset (as determined by increased alpha angle) in the setting of cam-type impingement (Figure 1).4 Pincer-type impingement may be associated with a crossover sign, coxa profunda, and an increased center-edge angle (CEA). Advanced imaging studies, such as computed tomography (CT), magnetic resonance imaging (MRI) arthrogram, and delayed gadolinium-enhanced MRI of cartilage (dGEMRIC), are commonly used to better delineate bony deformity and concomitant injuries of the labrum and cartilage (Figure 2).
Treatment for FAI often consists initially of activity modification, use of anti-inflammatory medications, and physical therapy. Intra-articular corticosteroid injections may be used both diagnostically and therapeutically. When nonsurgical measures fail to adequately relieve symptoms, surgery may be warranted. Whether performed open or arthroscopically, surgery is directed first at correcting the underlying osseous abnormality—performing an osteoplasty of the proximal femur to remove the cam lesion, performing an acetabular osteoplasty (“rim-trimming”) to address a focal pincer lesion, and/or performing a periacetabular osteotomy to decrease global acetabular overcoverage (Figure 3).5
Sex-Based Differences in FAI Incidence
Traditionally, it was thought that cam-type impingement occurred predominantly in young, athletic males, whereas pincer-type impingement resulting from acetabular overcoverage occurred primarily in females during their fourth decade. However, our understanding of the sex-based differences in the incidence and presentation of FAI has evolved, and it is now clear that the interplay of sex, radiographic signs of impingement, and development of symptoms requiring treatment is more complex.
In recent large population-based studies, investigators have attempted to better characterize the sex-based differences in the incidence of osseous FAI deformity. Gosvig and colleagues2 examined radiographic and questionnaire outcomes of 3620 patients (age range, 21-90 years) and found that males were more likely than females to have a pistol-grip deformity of the hip (19.6% vs 5.2%); that deep acetabular sockets were common in both sexes (15.2% vs 19.4%); and that the presence of pistol-grip deformity or deep socket was significantly associated with development of osteoarthritis, independent of sex.
In a study of 2081 asymptomatic patients (mean age, 18.6 years), Laborie and colleagues4 reported similar radiographic findings. Males were significantly more likely than females to have a cam-type deformity, as evidenced by pistol-grip deformity, focal prominence of the femoral neck, and/or flattening of the lateral aspect of the femoral head. Males were also more likely than females to have a pincer deformity, though radiographic signs of pincer deformity—a crossover sign, excessive acetabular coverage (defined by increased CEA), and a posterior wall sign—were common in both sexes, occurring in 16.6% of females and 34.3% of males. Bilateral findings of FAI-associated deformity were also more common in males than in females, both for cam-type deformity (24.7% vs 6.3%) and pincer-type deformity (21.7% vs 9.7%).
Sex-Based Differences in FAI Presentation
In males and females, the clinical presentation of FAI is similar—insidious onset of deep groin pain, often exacerbated with activity, and physical examination findings of decreased hip motion (particularly internal rotation) and a positive impingement test.3 Nevertheless, the sexes’ clinical presentation differs in several ways. Specifically, in a study using 3-dimensional CT to assess bony deformity in both symptomatic and asymptomatic patients, Beaulé and colleagues6 reported that alpha angles were significantly higher in symptomatic males than in symptomatic females (73.3° vs 58.7°). Hetsroni and colleagues7 recently reported similar results in a study of 217 symptomatic young adults treated arthroscopically for hip pain. Preoperative CT showed that alpha angles were significantly larger in males than in females (63.6° vs 47.8°). The authors postulated that females may be more likely to be symptomatic in the setting of smaller cam lesions because of the increased peak hip flexion and frontal plane motion commonly demonstrated by females during drop landings in sport. The authors further hypothesized that sex differences in muscle mass (which contributes to dynamic hip stability) and ligamentous laxity (a component of static hip stability) may result in larger physiologic ranges of motion for many females. As a result, bony impingement may occur in the setting of smaller anatomical lesions in females. The authors further noted that, compared with their male counterparts, females being treated for symptomatic FAI had significantly more femoral and acetabular anteversion.
Another male–female presentation difference involves symptom bilaterality. Specifically, males are significantly more likely than females to have symptomatic FAI involving both hips. In a recent study of 646 patients who underwent hip arthroscopy for symptomatic FAI during a 2-year period, Klingenstein and colleagues8 found that females constituted 48.2% of unilateral arthroscopy patients but only 34.8% of bilateral arthroscopy patients. The odds ratio of males treated for both hips, compared with females, was 1.7 (95% confidence interval, 1.16–2.54).
Last, it has been reported that, on clinical presentation, hip function scores are significantly lower in females than in males. In a recent study of 612 cases of symptomatic FAI treated with hip arthroscopy, Malviya and colleagues9 found that females had significantly lower quality-of-life scores both before and after surgery. Hetsroni and colleagues7 reported similar findings, with females having significantly lower preoperative modified Harris Hip Scores and lower Hip Outcome Scores in the domains of Activities of Daily Living and Sports.
Sex-Based Differences in FAI Treatment
and Outcomes
Surgical treatment of FAI is focused on identifying the source of hip pain and dysfunction—be it osseous lesion, labral tearing, chondral injury, or iliopsoas tendonitis—and treating it accordingly, regardless of sex. Most studies of this approach find consistent improvement in the short-term and midterm outcome scores for a majority of patients. However, relatively few studies have focused specifically on sex in determining the percentage of patients who require surgical treatment, in deciding the type of surgery that should be performed, or in measuring surgical outcomes in patients with symptomatic FAI.
In their review of 23 studies of FAI surgery, Ng and colleagues10 found that, of 970 patients, 608 (62.7%) were male and 362 (37.3%) were female. Similarly higher rates for males were previously published.5,11 More recently, Clohisy and colleagues12 reported on the descriptive epidemiology of patients having surgery for FAI at 8 different medical centers in North America. Fifty-five percent of the hips surgically treated for symptomatic FAI were females’. The authors speculated that this unexpectedly high rate could have resulted from US and Canadian female athletes’ increasingly higher level of sports participation. The results of this study, one of the largest examining the rate of surgery for males and females with FAI, suggest that females are more likely to have surgery for symptomatic FAI despite being less likely to have radiographic evidence of impingement. Our understanding of this phenomenon continues to advance.
In a recent prospective study, Krych and colleagues13 evaluated the clinical outcomes of FAI surgeries (labral débridement, labral repair) in an all-female patient cohort. Female patients with symptomatic FAI were randomized to undergo either labral débridement or labral repair. There were clinical improvements in both groups, but, compared with labral débridement patients, labral repair patients had more significantly improved Hip Outcome Scores in the domains of Activities of Daily Living and Sports, as well as better subjective outcomes. Although the study did not compare female patients with male patients, it does provide evidence that female patients specifically may benefit more from labral repair than from labral débridement alone.
With respect to different surgical treatments for male and female patients, Hetsroni and colleagues7 introduced the idea of sex-specific treatment when they noted more hip anteversion in their study’s female patients than in its male patients. They suggested that, because the anterosuperior acetabulum is subjected to a high amount of stress during weight-bearing and gait, this area in females with suspected pincer lesions should be rim-trimmed judiciously to avoid increasing the stress and perhaps even hastening the development of degenerative disease. Last, though several authors have noted that hip function scores are lower in females than in males on presentation, it has also been reported that females demonstrate more improvement in functional scores after surgery.9 This may be important information to discuss during preoperative counseling about expected goals and outcomes.
Conclusion
Femoroacetabular impingement is a common clinical entity that affects both males and females. However, sexual dimorphism in FAI incidence, presentation, treatment, and outcomes has recently been described in the literature (Table). Being aware of these sex-based differences and tailoring patient evaluation and management accordingly will likely result in optimal outcomes for each person who presents with symptomatic FAI.
Femoroacetabular impingement (FAI), a recently described hip condition in adolescents and young adults, results from abnormal physical contact between the proximal femur and the acetabulum.1 FAI is usually characterized by the site of the predominant morphologic abnormality—proximal femur (cam-type FAI), acetabulum (pincer-type FAI), or both (mixed impingement). Cam-type FAI is typified by the aspherical extension of the articular surface at the anterosuperior head–neck junction of the proximal femur with loss of the normal offset. With hip motion, especially in the maximal ranges of flexion and internal rotation, the aspherical proximal femur repeatedly contacts the anterosuperior acetabulum, damaging the chondrolabral junction and ultimately the labrum itself. In pincer-type impingement, femoral head overcoverage caused by acetabular retroversion and/or coxa profunda directly damages the anterior labrum when the acetabular rim contacts the proximal femur during physiologic motion. “Contrecoup” injury of the posterior-inferior acetabular cartilage may also occur. Over time, recurrent microtrauma to the acetabular cartilage and/or labrum may lead to degenerative changes of the hip and ultimately to premature osteoarthritis.1,2
Patients with FAI typically present with groin pain that may be activity-related or that may occur with prolonged sitting with the hip in a flexed position. Physical examination findings suggestive of FAI include decreased passive internal hip rotation and reproducible pain with adduction and internal rotation of the flexed hip—the impingement sign, or the flexion, adduction, and internal rotation (FADIR) test.3 Diagnostic imaging evaluation initially includes radiographs of the pelvis and hips. These radiographs may show a “pistol-grip” deformity and/or decreased head–neck offset (as determined by increased alpha angle) in the setting of cam-type impingement (Figure 1).4 Pincer-type impingement may be associated with a crossover sign, coxa profunda, and an increased center-edge angle (CEA). Advanced imaging studies, such as computed tomography (CT), magnetic resonance imaging (MRI) arthrogram, and delayed gadolinium-enhanced MRI of cartilage (dGEMRIC), are commonly used to better delineate bony deformity and concomitant injuries of the labrum and cartilage (Figure 2).
Treatment for FAI often consists initially of activity modification, use of anti-inflammatory medications, and physical therapy. Intra-articular corticosteroid injections may be used both diagnostically and therapeutically. When nonsurgical measures fail to adequately relieve symptoms, surgery may be warranted. Whether performed open or arthroscopically, surgery is directed first at correcting the underlying osseous abnormality—performing an osteoplasty of the proximal femur to remove the cam lesion, performing an acetabular osteoplasty (“rim-trimming”) to address a focal pincer lesion, and/or performing a periacetabular osteotomy to decrease global acetabular overcoverage (Figure 3).5
Sex-Based Differences in FAI Incidence
Traditionally, it was thought that cam-type impingement occurred predominantly in young, athletic males, whereas pincer-type impingement resulting from acetabular overcoverage occurred primarily in females during their fourth decade. However, our understanding of the sex-based differences in the incidence and presentation of FAI has evolved, and it is now clear that the interplay of sex, radiographic signs of impingement, and development of symptoms requiring treatment is more complex.
In recent large population-based studies, investigators have attempted to better characterize the sex-based differences in the incidence of osseous FAI deformity. Gosvig and colleagues2 examined radiographic and questionnaire outcomes of 3620 patients (age range, 21-90 years) and found that males were more likely than females to have a pistol-grip deformity of the hip (19.6% vs 5.2%); that deep acetabular sockets were common in both sexes (15.2% vs 19.4%); and that the presence of pistol-grip deformity or deep socket was significantly associated with development of osteoarthritis, independent of sex.
In a study of 2081 asymptomatic patients (mean age, 18.6 years), Laborie and colleagues4 reported similar radiographic findings. Males were significantly more likely than females to have a cam-type deformity, as evidenced by pistol-grip deformity, focal prominence of the femoral neck, and/or flattening of the lateral aspect of the femoral head. Males were also more likely than females to have a pincer deformity, though radiographic signs of pincer deformity—a crossover sign, excessive acetabular coverage (defined by increased CEA), and a posterior wall sign—were common in both sexes, occurring in 16.6% of females and 34.3% of males. Bilateral findings of FAI-associated deformity were also more common in males than in females, both for cam-type deformity (24.7% vs 6.3%) and pincer-type deformity (21.7% vs 9.7%).
Sex-Based Differences in FAI Presentation
In males and females, the clinical presentation of FAI is similar—insidious onset of deep groin pain, often exacerbated with activity, and physical examination findings of decreased hip motion (particularly internal rotation) and a positive impingement test.3 Nevertheless, the sexes’ clinical presentation differs in several ways. Specifically, in a study using 3-dimensional CT to assess bony deformity in both symptomatic and asymptomatic patients, Beaulé and colleagues6 reported that alpha angles were significantly higher in symptomatic males than in symptomatic females (73.3° vs 58.7°). Hetsroni and colleagues7 recently reported similar results in a study of 217 symptomatic young adults treated arthroscopically for hip pain. Preoperative CT showed that alpha angles were significantly larger in males than in females (63.6° vs 47.8°). The authors postulated that females may be more likely to be symptomatic in the setting of smaller cam lesions because of the increased peak hip flexion and frontal plane motion commonly demonstrated by females during drop landings in sport. The authors further hypothesized that sex differences in muscle mass (which contributes to dynamic hip stability) and ligamentous laxity (a component of static hip stability) may result in larger physiologic ranges of motion for many females. As a result, bony impingement may occur in the setting of smaller anatomical lesions in females. The authors further noted that, compared with their male counterparts, females being treated for symptomatic FAI had significantly more femoral and acetabular anteversion.
Another male–female presentation difference involves symptom bilaterality. Specifically, males are significantly more likely than females to have symptomatic FAI involving both hips. In a recent study of 646 patients who underwent hip arthroscopy for symptomatic FAI during a 2-year period, Klingenstein and colleagues8 found that females constituted 48.2% of unilateral arthroscopy patients but only 34.8% of bilateral arthroscopy patients. The odds ratio of males treated for both hips, compared with females, was 1.7 (95% confidence interval, 1.16–2.54).
Last, it has been reported that, on clinical presentation, hip function scores are significantly lower in females than in males. In a recent study of 612 cases of symptomatic FAI treated with hip arthroscopy, Malviya and colleagues9 found that females had significantly lower quality-of-life scores both before and after surgery. Hetsroni and colleagues7 reported similar findings, with females having significantly lower preoperative modified Harris Hip Scores and lower Hip Outcome Scores in the domains of Activities of Daily Living and Sports.
Sex-Based Differences in FAI Treatment
and Outcomes
Surgical treatment of FAI is focused on identifying the source of hip pain and dysfunction—be it osseous lesion, labral tearing, chondral injury, or iliopsoas tendonitis—and treating it accordingly, regardless of sex. Most studies of this approach find consistent improvement in the short-term and midterm outcome scores for a majority of patients. However, relatively few studies have focused specifically on sex in determining the percentage of patients who require surgical treatment, in deciding the type of surgery that should be performed, or in measuring surgical outcomes in patients with symptomatic FAI.
In their review of 23 studies of FAI surgery, Ng and colleagues10 found that, of 970 patients, 608 (62.7%) were male and 362 (37.3%) were female. Similarly higher rates for males were previously published.5,11 More recently, Clohisy and colleagues12 reported on the descriptive epidemiology of patients having surgery for FAI at 8 different medical centers in North America. Fifty-five percent of the hips surgically treated for symptomatic FAI were females’. The authors speculated that this unexpectedly high rate could have resulted from US and Canadian female athletes’ increasingly higher level of sports participation. The results of this study, one of the largest examining the rate of surgery for males and females with FAI, suggest that females are more likely to have surgery for symptomatic FAI despite being less likely to have radiographic evidence of impingement. Our understanding of this phenomenon continues to advance.
In a recent prospective study, Krych and colleagues13 evaluated the clinical outcomes of FAI surgeries (labral débridement, labral repair) in an all-female patient cohort. Female patients with symptomatic FAI were randomized to undergo either labral débridement or labral repair. There were clinical improvements in both groups, but, compared with labral débridement patients, labral repair patients had more significantly improved Hip Outcome Scores in the domains of Activities of Daily Living and Sports, as well as better subjective outcomes. Although the study did not compare female patients with male patients, it does provide evidence that female patients specifically may benefit more from labral repair than from labral débridement alone.
With respect to different surgical treatments for male and female patients, Hetsroni and colleagues7 introduced the idea of sex-specific treatment when they noted more hip anteversion in their study’s female patients than in its male patients. They suggested that, because the anterosuperior acetabulum is subjected to a high amount of stress during weight-bearing and gait, this area in females with suspected pincer lesions should be rim-trimmed judiciously to avoid increasing the stress and perhaps even hastening the development of degenerative disease. Last, though several authors have noted that hip function scores are lower in females than in males on presentation, it has also been reported that females demonstrate more improvement in functional scores after surgery.9 This may be important information to discuss during preoperative counseling about expected goals and outcomes.
Conclusion
Femoroacetabular impingement is a common clinical entity that affects both males and females. However, sexual dimorphism in FAI incidence, presentation, treatment, and outcomes has recently been described in the literature (Table). Being aware of these sex-based differences and tailoring patient evaluation and management accordingly will likely result in optimal outcomes for each person who presents with symptomatic FAI.
1. Ganz R, Parvizi J, Beck M, Leunig M, Notzli H, Siebenrock KA. Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop. 2003;(417):112-120.
2. Gosvig KK, Jacobsen S, Sonne-Holm S, Palm H, Troelsen A. Prevalence of malformations of the hip joint and their relationship to sex, groin pain, and risk of osteoarthritis: a population-based survey. J Bone Joint Surg Am. 2010;92(5):1162-1169.
3. Philippon MJ, Maxwell RB, Johnston TL, Schenker M, Briggs KK. Clinical presentation of femoroacetabular impingement. Knee Surg Sports Traumatol Arthrosc. 2007;15(8):1041-1047.
4. Laborie LB, Lehmann TG, Engesaeter IO, Eastwood DM, Engesaeter LB, Rosendahl K. Prevalence of radiographic findings thought to be associated with femoroacetabular impingement in a population-based cohort of 2081 healthy young adults. Radiology. 2011;260(2):494-502.
5. Clohisy JC, St John LC, Schutz AL. Surgical treatment of femoroacetabular impingement: a systematic review of the literature. Clin Orthop. 2010;468(2):555-564.
6. Beaulé PE, Zaragoza E, Motamedi K, Copelan N, Dorey FJ. Three-dimensional computed tomography of the hip in the assessment of femoroacetabular impingement. J Orthop Res. 2005;23(6):1286-1292.
7. Hetsroni I, Dela Torre K, Duke G, Lyman S, Kelly BT. Sex differences of hip morphology in young adults with hip pain and labral tears. Arthroscopy. 2013;29(1):54-63.
8. Klingenstein GG, Zbeda RM, Bedi A, Magennis E, Kelly BT. Prevalence and preoperative demographic and radiographic predictors of bilateral femoroacetabular impingement. Am J Sports Med. 2013;41(4):762-768.
9. Malviya A, Stafford GH, Villar RN. Impact of arthroscopy of the hip for femoroacetabular impingement on quality of life at a mean follow-up of 3.2 years. J Bone Joint Surg Br. 2012;94(4):466-470.
10. Ng VY, Arora N, Best TM, Pan X, Ellis TJ. Efficacy of surgery for femoroacetabular impingement: a systematic review. Am J Sports Med. 2010;38(11):2337-2345.
11. Matsuda DK, Carlisle JC, Arthurs SC, Wierks CH, Philippon MJ. Comparative systematic review of the open dislocation, mini-open, and arthroscopic surgeries for femoroacetabular impingement. Arthroscopy. 2011;27(2):252-269.
12. Clohisy JC, Baca G, Beaule PE, et al. Descriptive epidemiology of femoroacetabular impingement: a North American cohort of patients undergoing surgery. Am J Sports Med. 2013;41(6):1348-1356.
13. Krych AJ, Thompson M, Knutson Z, Scoon J, Coleman SH. Arthroscopic labral repair versus selective labral debridement in female patients with femoroacetabular impingement: a prospective randomized study. Arthroscopy. 2013;29(1):46-53.
1. Ganz R, Parvizi J, Beck M, Leunig M, Notzli H, Siebenrock KA. Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop. 2003;(417):112-120.
2. Gosvig KK, Jacobsen S, Sonne-Holm S, Palm H, Troelsen A. Prevalence of malformations of the hip joint and their relationship to sex, groin pain, and risk of osteoarthritis: a population-based survey. J Bone Joint Surg Am. 2010;92(5):1162-1169.
3. Philippon MJ, Maxwell RB, Johnston TL, Schenker M, Briggs KK. Clinical presentation of femoroacetabular impingement. Knee Surg Sports Traumatol Arthrosc. 2007;15(8):1041-1047.
4. Laborie LB, Lehmann TG, Engesaeter IO, Eastwood DM, Engesaeter LB, Rosendahl K. Prevalence of radiographic findings thought to be associated with femoroacetabular impingement in a population-based cohort of 2081 healthy young adults. Radiology. 2011;260(2):494-502.
5. Clohisy JC, St John LC, Schutz AL. Surgical treatment of femoroacetabular impingement: a systematic review of the literature. Clin Orthop. 2010;468(2):555-564.
6. Beaulé PE, Zaragoza E, Motamedi K, Copelan N, Dorey FJ. Three-dimensional computed tomography of the hip in the assessment of femoroacetabular impingement. J Orthop Res. 2005;23(6):1286-1292.
7. Hetsroni I, Dela Torre K, Duke G, Lyman S, Kelly BT. Sex differences of hip morphology in young adults with hip pain and labral tears. Arthroscopy. 2013;29(1):54-63.
8. Klingenstein GG, Zbeda RM, Bedi A, Magennis E, Kelly BT. Prevalence and preoperative demographic and radiographic predictors of bilateral femoroacetabular impingement. Am J Sports Med. 2013;41(4):762-768.
9. Malviya A, Stafford GH, Villar RN. Impact of arthroscopy of the hip for femoroacetabular impingement on quality of life at a mean follow-up of 3.2 years. J Bone Joint Surg Br. 2012;94(4):466-470.
10. Ng VY, Arora N, Best TM, Pan X, Ellis TJ. Efficacy of surgery for femoroacetabular impingement: a systematic review. Am J Sports Med. 2010;38(11):2337-2345.
11. Matsuda DK, Carlisle JC, Arthurs SC, Wierks CH, Philippon MJ. Comparative systematic review of the open dislocation, mini-open, and arthroscopic surgeries for femoroacetabular impingement. Arthroscopy. 2011;27(2):252-269.
12. Clohisy JC, Baca G, Beaule PE, et al. Descriptive epidemiology of femoroacetabular impingement: a North American cohort of patients undergoing surgery. Am J Sports Med. 2013;41(6):1348-1356.
13. Krych AJ, Thompson M, Knutson Z, Scoon J, Coleman SH. Arthroscopic labral repair versus selective labral debridement in female patients with femoroacetabular impingement: a prospective randomized study. Arthroscopy. 2013;29(1):46-53.
