This issue of eMedRef provides information to clinicians on the pathophysiology, diagnosis, and therapeutics of femoral acetabular impingement

Burroughs, Kevin

Strickland, Michelle

English

University of Missouri: MOspace

Femoral Acetabular Impingement Page 1 of 5    3.1.12   FEMORAL ACETABULAR IMPINGEMENT   Background   1. Definition - Osseous deformities on acetabular rim, femoral head-neck junction or both o At extremes of hip motion, can cause injury to acetabular labrum and cartilage  o Results in pain and loss of motion.1 2. General Information – Two Types o Cam type – Anterior femoral neck loses concave anatomy o Osseous bump impinges on labrum with hip flexion.    More common in young males. o Pincer type - Arises when anterior acetabular rim is prominent relative to posterior rim, or there is excessive coverage of acetabulum  Impinges on femoral neck during movement.   More common in middle aged women. o Mixed type can occur  Pathophysiology    1. Pathology of Disease - aberrant contact between acetabular rim and femoral head-neck complex during terminal motion o Causes lesions on acetabular rim or labrum leading to degenerative changes.2 2. Prevalence   o Radiographic findings: In cohort of over 2,000 young adults  CAM impingement occurred in 35% of males, and 10% of                                           females  Pincer type occurred in 34% of males and 17% of females.3 o Clinical prevalence of hip impingement estimated at 10-15%.3 3. Risk Factors  o Non spherical femoral head  o Coxa Vara/Profunda o Mal-united femoral neck fracture o Legg-Calve-Perthes disease o Slipped capital femoral epiphysis o Prior femoral osteomy o Os acetabuli o Post-trauma o Protrusio acetabuli. 4. Morbidity / Mortality–can be a cause of chronic hip pain.  o Reportedly associated with an increased risk of developing  osteoarthritis at an earlier age2.  o Also an association with increased incidence of labral tears.  Diagnostics  1. History  o Commonly insidious onset o Young active adults o Pain initially intermittent, worsened by activities with terminal motion Femoral Acetabular Impingement Page 2 of 5    3.1.12   o Pain deep in anterior hip/groin o Catching, locking, clicking o Pain worse after prolonged sitting or stair climbing (SOR:B).4 2. Physical Examination  o Positive C-Sign  Patient identifies the location of pain by gripping hip between abducted thumb and index finger just above and slightly anterior to greater trochanter  o Limitation of internal rotation and adduction  Pain with FADIR test (forcing the hip into Flexion ADduction and Internal Rotation - (SOR:B)4 o Limitation of flexion, abduction and external rotation (FABER) (SOR:B)4 o Posterior Inferior Impingement test  Pain with passive external rotation of a hyperextended hip4 5. Laboratory evaluation–none directly for condition o In appropriate clinical setting rheumatologic testing may be necessary to  exclude other diagnoses. 6. Diagnostic imaging o Radiographs  Standing AP of pelvis to look for cross-over sign and to evaluate  for arthritic changes.   Dunn view: Axial view of hip with hip in 45 degrees of flexion  and abducted 20 degrees will evaluate for:  Osseous protuberance on anterior aspect of femoral neck  Reduced offset of femoral head-neck junction  Pronounced acetabular rim  Can be used to measure the alpha angle (SOR:A)5,6,7  Cross-over sign  Anterior acetabular wall crosses over posterior wall and  projects laterally rather than medially as it does in normal acetabulum1  Alpha Angle  Angle between line drawn from center of femoral head through central axis of femoral neck and a second line drawn from center of head exceeds radius of subchondral femoral head  Normal is less than 55 degrees o MR arthrogram  MRI identifies depth and coverage of acetabulum, anterior  femoral neck thickening or abnormal osseous protrusion.   Arthrogram enhances identification of labral tears.(SOR:B)5,6,7 7. Diagnostic Criteria o Presence of clinical signs of impingement (SOR:B) o Evidence of Pincher Impingement/Alpha Angle greater than 55 degrees (SOR B) o Evidence of Cam Impingement/Crossover sign (SOR:B)    Femoral Acetabular Impingement Page 3 of 5    3.1.12   Differential Diagnosis  1. Key Differential Diagnoses o Athletic Pubalgia/sports hernia o Developmental dysplasia of the hip o Groin strain o Osteonecrosis of the femoral head o Iliopsoas impingement/Snapping hip o Trochanteric bursitis o Septic arthritis o Intra-articular loose body o Extensive Differential Diagnoses o Tumor of pelvis or spine o Intra-abdominal/pelvic pathology - appendix, ovarian cyst, endometriosis o Direct/Indirect Hernia  Therapeutics  1. Conservative Management8,9,10 o Initially patients undergo either rest, or relative rest depending on severity of symptoms. o For mild symptoms  Avoid motions and activities that exacerbate symptoms.   Seat position modification in biking   When running, avoid treadmill and narrow straight trails; instead use zigzag or open courses.11 o NSAIDs for pain and/or other inflammatory causes. o Physical Therapy/Stretching  Improve external rotation and abduction  If tolerated well, add internal rotation stretches and flexion o Corticosteroid Intra-Articular Injections  Can be used alone or in combination with MR arthrogram to provide diagnostic information  Pain improvement can indicate intra-articular pathology o Surgical Management  Open approach includes visualization of femoral head, labrum and                                                         acetabulum by dislocating hip  Followed by removal of CAM and/or Pincher defects and possible repair or debridement of labral tears12,13  Arthroscopic approaches include examination of central                           compartment (inside joint capsule) with debridement and                          peripheral compartment with debridement/resection of                                    osteophytes.8   Follow-Up   1. Return to Office o Patients will likely need 4-6 weeks of modified activity and physical therapy interventions before follow-up. o Worsening of pain symptoms, mechanical or locking symptoms should follow-up sooner as surgical necessity is more likely.  Femoral Acetabular Impingement Page 4 of 5    3.1.12   2. Refer to Specialist o Diagnostic studies that indicate labral and/or articular cartilage pathology o Failure to improve symptoms after conservative management in those with CAM or pincer morphology without identified labral tear  Prognosis  1. Not well documented. 2. Current literature only discusses short-term and mid-term follow-up o Long-term follow-up studies limited at this time.  Prevention  1. None  Patient Education 1. Handout from American Academy Family Physicians - Hip Impingement 2. Handout from American Academy of Orthopedic Surgeons - Femoroacetabular Impingement  References  1. Tannast, M., Siebenrock, K., Anderson, S. Femoroacetabular Impingement Radiographic Diagnosis - What the Radiologist Should Know.  AJR. 2007; 188:1540-1552. 2. Ganz, R., Parvizi, J., Beck, M., Leunig, M., Notzli, H, Siebenrock, K. Femoroacetabular Impingement: A Cause for Osteoarthritis of the Hip. Clin Orthop Relat R. 2003; 417:112-120, December.  3. Laborie, L., Lehmann, T., Engesaeter, I., Eastwood, D., Engesaeter, L., Rosendahl, K., Prevalence of Radiographic Findings Thought to be Associated with Femoroacetabular Impingement in a Population-based Cohort of 2081 Healthy Young Adults.  Radiology. Volume 260: Number 2—August 2011. 4. Banerjee, P., Melean, C. Femoroacetabular Impingement: A Review of Diagnosis and Management.  Curr Rev Musculoskelet Med. 2011; 4:23-32. 5. Fadul, D., Carrino, J.  Imaging of Femoroacetabular Impingement.  J Bone Joint Surg (Am). 2009; 91 Suppl 1:138-143.  6. Pfirmann, C., Mengiardi, B., Dora, C., Kalberer, F., Zanetti, M., Hodler, J. Cam and Pincer Femoroacetabular Impingement: Characteristic MR Arthrographic Findings in 50 patients. Radiology.  2006; 240:3, 778-785. 7. Leunig, M., Robertson, W., Ganz, R. Femoroacetabular Impingement: Diagnosis and Management, Including Open Surgical Technique. Oper Tech Sports Med.  15:178-188. 8. Crawford, J., Villar, R. Current Concepts in the Management of Femoroacetabular Impingement. J Bone Joint Surg (Br). 2005; Nov 87(11):1459-62. 9. Lavigne, M., Parvizi, J., Beck, M., Siebenrock, K., Ganz, R., Leunig, M. Anterior Femoroacetabular Impingement. Part I: Techniques of Joint Preserving Surgery. Clin Orthop Relat R. 2004; 418:61-6. 10. Samora, J., Ng, V., Ellis, T. Femoroacetabular Impingement: A Common Cause of Hip Pain in Young Adults. Clin Journal Sport Med. 2011;21(1):51-56 11. Emara, K., Samir, W., Motasem, H., Ghafar, K.  Conservative Treatment for Mild Femoroacetabular Impingment.  Journal of Orthopaedic Surgery. 2011; 19(1):41-5. Femoral Acetabular Impingement Page 5 of 5    3.1.12   12. Beck, M., Leunig, M., Parvizi, J., Boutier, V., Wyss, D., Ganz, R. Anterior Femoroacetabular Impingement. Part II: Midterm Results of Surgical Treatment. Clin Orthop Relat R. 2004; 418:67-73. 13. Murphy, S., Tannast, M., Kim, Y., Buly, R., Millis, M. Debridement of the Adult Hip for Femoroacetabular Impingement: Indications and Preliminary Clinical Results. Clin Orthop Relat R. 2004; 429:178-81.   Authors:  Michelle Strickland, MD, & Kevin Burroughs, MD, Cabarrus FMRP, NC  Editor:  Carol Scott, MD, University of Nevada Reno FPRP  

Femoral acetabular impingement

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Femoral acetabular impingement

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