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KEY FACTS
Terminology
Imaging
Pathology
Clinical Issues
Diagnostic Checklist
TERMINOLOGY
Abbreviations
- Femoral acetabular impingement (FAI)
Definitions
- Morphologic abnormality at femoral head-neck junction or acetabulum resulting in osseous &/or labral and cartilaginous impingement
- Cam type: prominence at femoral head-neck junction impinges anterosuperior acetabulum
- Decreased femoral head-neck offset (aspherical femoral head)
- Bump at anterolateral femoral head-neck junction: may result from eccentric skeletal maturation
- Flat anterosuperior femoral head-neck junction: may reflect subclinical slipped capital femoral epiphysis
- Primarily young men
- Pincer type: prominence of anterior acetabulum leads to impingement on femoral neck
- Coxa profunda: acetabulum too deep with excessive surface area
- Posterior acetabular deficiency: femoral head shifts posteriorly with hip flexion, increasing coverage by acetabulum anteriorly
- Primarily middle-aged women
- May have both cam and pincer FAI in same patient
- Most common morphology is combined
- Cam type: prominence at femoral head-neck junction impinges anterosuperior acetabulum
- Morphologic abnormality at femoral head-neck junction or acetabulum resulting in osseous &/or labral and cartilaginous impingement
IMAGING
General Features
Radiographic Findings
MR Findings
Imaging Recommendations
Pitfalls
DIFFERENTIAL DIAGNOSIS
PATHOLOGY
General Features
Staging, Grading, & Classification
Gross Pathologic & Surgical Features
Microscopic Features
CLINICAL ISSUES
Presentation
Natural History & Prognosis
Treatment
DIAGNOSTIC CHECKLIST
Consider
Image Interpretation Pearls
Reporting Tips
Selected References
- Welton KL et al: The anteroposterior pelvic radiograph: acetabular and femoral measurements and relation to hip pathologies. J Bone Joint Surg Am. 100(1):76-85, 2018
- Petersen BD et al: Lateral acetabular labral length is inversely related to acetabular coverage as measured by lateral center edge angle of Wiberg. J Hip Preserv Surg. 3(3):190-6, 2016
- Sutter R et al: Assessment of femoral antetorsion with MRI: comparison of oblique measurements to standard transverse measurements. AJR Am J Roentgenol. 205(1):130-5, 2015
- Byrd JW: Femoroacetabular impingement in athletes: current concepts. Am J Sports Med. 42(3):737-51, 2014
- Lepage-Saucier M et al: Femoroacetabular impingement: normal values of the quantitative morphometric parameters in asymptomatic hips. Eur Radiol. 24(7):1707-14, 2014
- Omoumi P et al: Anatomic features associated with femoroacetabular impingement are equally common in hips of old and young asymptomatic individuals without CT signs of osteoarthritis. AJR Am J Roentgenol. 202(5):1078-86, 2014
- Riley GM et al: MRI of the hip for the evaluation of femoroacetabular impingement; past, present, and future. J Magn Reson Imaging. 41(3):558-72, 2014
- Tranovich MJ et al: A review of femoroacetabular impingement and hip arthroscopy in the athlete. Phys Sportsmed. 42(1):75-87, 2014
- Bredella MA et al: Femoroacetabular impingement. Magn Reson Imaging Clin N Am. 21(1):45-64, 2013
- Dimmick S et al: Femoroacetabular impingement. Radiol Clin North Am. 51(3):337-52, 2013
- Nepple JJ et al: Coxa profunda is not a useful radiographic parameter for diagnosing pincer-type femoroacetabular impingement. J Bone Joint Surg Am. 95(5):417-23, 2013
- Petchprapa CN et al: Imaging of chondral lesions including femoroacetabular impingement. Semin Musculoskelet Radiol. 17(3):258-71, 2013
- Philippon MJ et al: Prevalence of increased alpha angles as a measure of cam-type femoroacetabular impingement in youth ice hockey players. Am J Sports Med. 41(6):1357-62, 2013
- Rubin DA: Femoroacetabular impingement: fact, fiction, or fantasy? AJR Am J Roentgenol. 201(3):526-34, 2013
- Sankar WN et al: Femoroacetabular impingement: current concepts and controversies. Orthop Clin North Am. 44(4):575-89, 2013
- Schmitz MR et al: Spectrum of radiographic femoroacetabular impingement morphology in adolescents and young adults: an EOS-based double-cohort study. J Bone Joint Surg Am. 95(13):e90, 2013
- Larson CM et al: Arthroscopic debridement versus refixation of the acetabular labrum associated with femoroacetabular impingement: mean 3.5-year follow-up. Am J Sports Med. 40(5):1015-21, 2012
- Robinson P: Conventional 3-T MRI and 1.5-T MR arthrography of femoroacetabular impingement. AJR Am J Roentgenol. 199(3):509-15, 2012
- Sutter R et al: Femoral antetorsion: comparing asymptomatic volunteers and patients with femoroacetabular impingement. Radiology. 263(2):475-83, 2012
- Sutter R et al: How useful is the alpha angle for discriminating between symptomatic patients with cam-type femoroacetabular impingement and asymptomatic volunteers? Radiology. 264(2):514-21, 2012
- Banerjee P et al: Femoroacetabular impingement: a review of diagnosis and management. Curr Rev Musculoskelet Med. 4(1):23-32, 2011
- Laborie LB et al: Prevalence of radiographic findings thought to be associated with femoroacetabular impingement in a population-based cohort of 2081 healthy young adults. Radiology. 260(2):494-502, 2011
- Palmer WE: Femoroacetabular impingement: caution is warranted in making imaging-based assumptions and diagnoses. Radiology. 257(1):4-7, 2010
- Jessel RH et al: Radiographic and patient factors associated with pre-radiographic osteoarthritis in hip dysplasia. J Bone Joint Surg Am. 91(5):1120-9, 2009
- Kang C et al: Acetabular labral tears in patients with sports injury. Clin Orthop Surg. 1(4):230-5, 2009
- Leunig M et al: The concept of femoroacetabular impingement: current status and future perspectives. Clin Orthop Relat Res. 467(3):616-22, 2009
- Lohan DG et al: Cam-type femoral-acetabular impingement: is the alpha angle the best MR arthrography has to offer? Skeletal Radiol. 38(9):855-62, 2009
- Pfirrmann CW et al: MR arthrography of acetabular cartilage delamination in femoroacetabular cam impingement. Radiology. 249(1):236-41, 2008
- Tannast M et al: Femoroacetabular impingement: radiographic diagnosis--what the radiologist should know. AJR Am J Roentgenol. 188(6):1540-52, 2007
- Blankenbaker DG et al: The painful hip: new concepts. Skeletal Radiol. 35(6):352-70, 2006
- Martinez AE et al: Os acetabuli in femoro-acetabular impingement: stress fracture or unfused secondary ossification centre of the acetabular rim? Hip Int. 16(4):281-6, 2006
- Bredella MA et al: MR imaging of femoroacetabular impingement. Magn Reson Imaging Clin N Am. 13(4):653-64, 2005
- Kassarjian A et al: Triad of MR arthrographic findings in patients with cam-type femoroacetabular impingement. Radiology. 236(2):588-92, 2005
- Siebenrock KA et al: Anterior femoro-acetabular impingement due to acetabular retroversion. Treatment with periacetabular osteotomy. J Bone Joint Surg Am. 85-A(2):278-86, 2003
- Ito K et al: Femoroacetabular impingement and the cam-effect. A MRI-based quantitative anatomical study of the femoral head-neck offset. J Bone Joint Surg Br. 83(2):171-6, 2001
- Abe I et al: Acetabular labrum: abnormal findings at MR imaging in asymptomatic hips. Radiology. 216(2):576-81, 2000
- Ferguson SJ et al: The influence of the acetabular labrum on hip joint cartilage consolidation: a poroelastic finite element model. J Biomech. 33(8):953-60, 2000
- Myers SR et al: Anterior femoroacetabular impingement after periacetabular osteotomy. Clin Orthop Relat Res. (363):93-9, 1999
- Tönnis D et al: Acetabular and femoral anteversion: relationship with osteoarthritis of the hip. J Bone Joint Surg Am. 81(12):1747-70, 1999
Related Anatomy
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Related Differential Diagnoses
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References
Tables
Tables
KEY FACTS
Terminology
Imaging
Pathology
Clinical Issues
Diagnostic Checklist
TERMINOLOGY
Abbreviations
- Femoral acetabular impingement (FAI)
Definitions
- Morphologic abnormality at femoral head-neck junction or acetabulum resulting in osseous &/or labral and cartilaginous impingement
- Cam type: prominence at femoral head-neck junction impinges anterosuperior acetabulum
- Decreased femoral head-neck offset (aspherical femoral head)
- Bump at anterolateral femoral head-neck junction: may result from eccentric skeletal maturation
- Flat anterosuperior femoral head-neck junction: may reflect subclinical slipped capital femoral epiphysis
- Primarily young men
- Pincer type: prominence of anterior acetabulum leads to impingement on femoral neck
- Coxa profunda: acetabulum too deep with excessive surface area
- Posterior acetabular deficiency: femoral head shifts posteriorly with hip flexion, increasing coverage by acetabulum anteriorly
- Primarily middle-aged women
- May have both cam and pincer FAI in same patient
- Most common morphology is combined
- Cam type: prominence at femoral head-neck junction impinges anterosuperior acetabulum
- Morphologic abnormality at femoral head-neck junction or acetabulum resulting in osseous &/or labral and cartilaginous impingement
IMAGING
General Features
Radiographic Findings
MR Findings
Imaging Recommendations
Pitfalls
DIFFERENTIAL DIAGNOSIS
PATHOLOGY
General Features
Staging, Grading, & Classification
Gross Pathologic & Surgical Features
Microscopic Features
CLINICAL ISSUES
Presentation
Natural History & Prognosis
Treatment
DIAGNOSTIC CHECKLIST
Consider
Image Interpretation Pearls
Reporting Tips
Selected References
- Welton KL et al: The anteroposterior pelvic radiograph: acetabular and femoral measurements and relation to hip pathologies. J Bone Joint Surg Am. 100(1):76-85, 2018
- Petersen BD et al: Lateral acetabular labral length is inversely related to acetabular coverage as measured by lateral center edge angle of Wiberg. J Hip Preserv Surg. 3(3):190-6, 2016
- Sutter R et al: Assessment of femoral antetorsion with MRI: comparison of oblique measurements to standard transverse measurements. AJR Am J Roentgenol. 205(1):130-5, 2015
- Byrd JW: Femoroacetabular impingement in athletes: current concepts. Am J Sports Med. 42(3):737-51, 2014
- Lepage-Saucier M et al: Femoroacetabular impingement: normal values of the quantitative morphometric parameters in asymptomatic hips. Eur Radiol. 24(7):1707-14, 2014
- Omoumi P et al: Anatomic features associated with femoroacetabular impingement are equally common in hips of old and young asymptomatic individuals without CT signs of osteoarthritis. AJR Am J Roentgenol. 202(5):1078-86, 2014
- Riley GM et al: MRI of the hip for the evaluation of femoroacetabular impingement; past, present, and future. J Magn Reson Imaging. 41(3):558-72, 2014
- Tranovich MJ et al: A review of femoroacetabular impingement and hip arthroscopy in the athlete. Phys Sportsmed. 42(1):75-87, 2014
- Bredella MA et al: Femoroacetabular impingement. Magn Reson Imaging Clin N Am. 21(1):45-64, 2013
- Dimmick S et al: Femoroacetabular impingement. Radiol Clin North Am. 51(3):337-52, 2013
- Nepple JJ et al: Coxa profunda is not a useful radiographic parameter for diagnosing pincer-type femoroacetabular impingement. J Bone Joint Surg Am. 95(5):417-23, 2013
- Petchprapa CN et al: Imaging of chondral lesions including femoroacetabular impingement. Semin Musculoskelet Radiol. 17(3):258-71, 2013
- Philippon MJ et al: Prevalence of increased alpha angles as a measure of cam-type femoroacetabular impingement in youth ice hockey players. Am J Sports Med. 41(6):1357-62, 2013
- Rubin DA: Femoroacetabular impingement: fact, fiction, or fantasy? AJR Am J Roentgenol. 201(3):526-34, 2013
- Sankar WN et al: Femoroacetabular impingement: current concepts and controversies. Orthop Clin North Am. 44(4):575-89, 2013
- Schmitz MR et al: Spectrum of radiographic femoroacetabular impingement morphology in adolescents and young adults: an EOS-based double-cohort study. J Bone Joint Surg Am. 95(13):e90, 2013
- Larson CM et al: Arthroscopic debridement versus refixation of the acetabular labrum associated with femoroacetabular impingement: mean 3.5-year follow-up. Am J Sports Med. 40(5):1015-21, 2012
- Robinson P: Conventional 3-T MRI and 1.5-T MR arthrography of femoroacetabular impingement. AJR Am J Roentgenol. 199(3):509-15, 2012
- Sutter R et al: Femoral antetorsion: comparing asymptomatic volunteers and patients with femoroacetabular impingement. Radiology. 263(2):475-83, 2012
- Sutter R et al: How useful is the alpha angle for discriminating between symptomatic patients with cam-type femoroacetabular impingement and asymptomatic volunteers? Radiology. 264(2):514-21, 2012
- Banerjee P et al: Femoroacetabular impingement: a review of diagnosis and management. Curr Rev Musculoskelet Med. 4(1):23-32, 2011
- Laborie LB et al: Prevalence of radiographic findings thought to be associated with femoroacetabular impingement in a population-based cohort of 2081 healthy young adults. Radiology. 260(2):494-502, 2011
- Palmer WE: Femoroacetabular impingement: caution is warranted in making imaging-based assumptions and diagnoses. Radiology. 257(1):4-7, 2010
- Jessel RH et al: Radiographic and patient factors associated with pre-radiographic osteoarthritis in hip dysplasia. J Bone Joint Surg Am. 91(5):1120-9, 2009
- Kang C et al: Acetabular labral tears in patients with sports injury. Clin Orthop Surg. 1(4):230-5, 2009
- Leunig M et al: The concept of femoroacetabular impingement: current status and future perspectives. Clin Orthop Relat Res. 467(3):616-22, 2009
- Lohan DG et al: Cam-type femoral-acetabular impingement: is the alpha angle the best MR arthrography has to offer? Skeletal Radiol. 38(9):855-62, 2009
- Pfirrmann CW et al: MR arthrography of acetabular cartilage delamination in femoroacetabular cam impingement. Radiology. 249(1):236-41, 2008
- Tannast M et al: Femoroacetabular impingement: radiographic diagnosis--what the radiologist should know. AJR Am J Roentgenol. 188(6):1540-52, 2007
- Blankenbaker DG et al: The painful hip: new concepts. Skeletal Radiol. 35(6):352-70, 2006
- Martinez AE et al: Os acetabuli in femoro-acetabular impingement: stress fracture or unfused secondary ossification centre of the acetabular rim? Hip Int. 16(4):281-6, 2006
- Bredella MA et al: MR imaging of femoroacetabular impingement. Magn Reson Imaging Clin N Am. 13(4):653-64, 2005
- Kassarjian A et al: Triad of MR arthrographic findings in patients with cam-type femoroacetabular impingement. Radiology. 236(2):588-92, 2005
- Siebenrock KA et al: Anterior femoro-acetabular impingement due to acetabular retroversion. Treatment with periacetabular osteotomy. J Bone Joint Surg Am. 85-A(2):278-86, 2003
- Ito K et al: Femoroacetabular impingement and the cam-effect. A MRI-based quantitative anatomical study of the femoral head-neck offset. J Bone Joint Surg Br. 83(2):171-6, 2001
- Abe I et al: Acetabular labrum: abnormal findings at MR imaging in asymptomatic hips. Radiology. 216(2):576-81, 2000
- Ferguson SJ et al: The influence of the acetabular labrum on hip joint cartilage consolidation: a poroelastic finite element model. J Biomech. 33(8):953-60, 2000
- Myers SR et al: Anterior femoroacetabular impingement after periacetabular osteotomy. Clin Orthop Relat Res. (363):93-9, 1999
- Tönnis D et al: Acetabular and femoral anteversion: relationship with osteoarthritis of the hip. J Bone Joint Surg Am. 81(12):1747-70, 1999
