synonyms: acetabular impingement
Femoroacetabular Impingement ICD-10
Femoroacetabular Impingement ICD-9
- 719.85 ther specified disorders of joint [0-9]; Calcification of joint; Fistula of joint;;Excludes:, pelvic region and thigh
- 719.95 (Unspecified disorder of joint; pelvic region and thigh)
Femoroacetabular Impingement Etiology / Epidemiology / Natural History
- May result from cam-type impingement in which adnormal bone/osteophyte on the femoral neck impinges on the acetabular labrum or pincer-type impingement in which abnormal acetabular bony/osteophyte prominence impinges into the femoral neck causing a kissing lesion. (Espinosa N, JBJS 2006;88A:925).
- Most common abnormal morphology = combined CAM/pincer deformity.
- Isolated CAM deformities commonly haveseparation between the acetabular cartilage and labrum.
- The ashperical femoral head causes abrasion damage to the acetabular labrum and rim cartilage eventually leading to early DJD.
- Genetic influences are important in the aetiology of primary femoroacetabular impingement. FAI is more common in siblings of patients with FAI, particularly with CAM deformity. (Pollard TC, Villar RN, Norton MR, Fern ED, Williams MR, Murray DW, Carr AJ. Genetic influences in the aetiology of femoroacetabular impingement: a sibling study. J Bone Joint Surg Br. 2010 Feb;92(2):209-16.)
Femoroacetabular Impingement Anatomy
- Can be related to coxa profunda, protrusion acetabuli, acetabluar retroversion, SCFE
- Abnormal contact between the femoral neck and the acetabular rim can lead to anterior-superior labral tear.
Femoroacetabular Impingement Clinical Evaluation
- Groin pain with prolonged sitting, driving and activity.
- May have limited hip motion.
- Groin pain exacerbated by hip internal rotation, flexion and adduction.
- Duchene sign = pt leans to the affected side while in stance phase of gait; indicates hip pathology.
- Loss of motion suggests intra/juxta-articular process
- Patrick's test: Groin pain with forcing hip into figure-of-4 postion, indicates hip pathology
- Stinchfield test: resisted straight leg raise causes groin pain, indicates hip pathology
- Labral pathology indicated by palpable click with moving from flexion/IR/adduction to extention/ER/abduction
- Snapping: Iliopsoas tendon snaps over iliopectineal eminence when flexed hip is extended with pt supine. Iliotibial band snaps over greater trochanter when standing pt rotates the adducted hip in stance phase.
Femoroacetabular Impingement Xray / Diagnositc Tests
- AP pelvis, cross-table lateral hip, AP hip c leg internally rotated 15. Evaluate femoral head sphericity, anterior neck prominences (lateral view). small herniation pits in the anterior neck. (Beall DP, Skeletal Radiol 2005;34:691).
- Cross-over sign: A/P hip view demonstrates retroversion of the acetabulum when the line of the anterior and posterior walls cross over each other. The line indicating the posterior wall of the acetabulum should be at or lateral to the center of the femoral head in the normal anteverted acetabulum (Reynolds D, JBJS 1999;81Br:281). Indicates acetabular retroversion.
- Lateral center edge angle: < 25 degrees is abnormal, indicates inadequate head coverage.
- Tonnis angle (acetabular inclination): normal is between 0 and 10 degrees.
- Head center position: distance from the medial aspect of the femoral head to the ilioischial line. Head is considered lateralized if >10 mm.
- Alpha angle: angle between the midline of the femoral neck and a line from the center of the femoral head to the point at which the femoral head becomes aspherical. Measured on lateral xray of the femoral neck or axial cut CT scan or MR image. (Peters CL, JBJS 2006;88Asuppl4;20)
- CT: 3D reconstructions helpful to detect femoral head-neck junction prominences.
- MRI: Diagnosis of FAI is best performed with MRI arthrogram increasing the sensitivity and specificity for labral pathology. Alpha angle is used to quantify impingement (Peters CL, JBJS 2006;88Asuppl4;20).
Femoroacetabular Impingement Classification / Treatment
- Cam-Type: abnormal anterior femoral neck impines on normal acetabulum and labrum, damaging the labrum.
-Treatment = resection of the prominence on the anterior femoral neck and debridement or repair of the larum. (Lavingne M, CORR 2004;418:67).
- Pincer-Type: abnormal anterior acetabular osteophyte contacts the anterior femoral neck.
-Treatment = debridement of the anterior acetabular osteophyte, labral repair / debridement, +/- periacetabular osteotomy. (Peters CL, JBJS 2006;88:1735).
- Consider Hip arthroscopy (Philippon MJ, Clin Sports Med 2006;25:299), Byrd JW, JAAOS 2006;14:433).
- Surgical treatment demonstrates good results, with the exception of those with osteoarthritis or Outerbridge grade III or grade IV cartilage damage or Acetabular dysplasia (normal lateral center-edge angle is 20° or greater and the acetabular index/Tönnis angle should be less than 10° or patient may have acetabular dyspasia).
Femoroacetabular Impingement Associated Injuries / Differential Diagnosis
- Acetabular Labral Tear
- Sports Hernia
- Hip arthritis
Femoroacetabular Impingement Complications
- Hip arthritis
- Acetabular stress fracture (Epstein N, JBJS 2009;91A:1480).
Femoroacetabular Impingement Follow-up Care
- 68% excellent results for surgical dislocation, no osteonecrosis occured in pts with impingement and minimal arthritic changes (Beck M, CORR 2004;418:67).
Femoroacetabular Impingement Review References
- Ganz R, JBJS 2001:83Br:1119
- Ng VY, Arora N, Best TM, Pan X, Ellis TJ. Efficacy of surgery for femoroacetabular impingement: a systematic review. Am J Sports Med. 2010 Nov;38(11):2337-45. Epub 2010 May 20.
- Philippon M, Schenker M, Briggs K, Kuppersmith D. Femoroacetabular impingement in 45 professional athletes: associated pathologies and return to sport following arthroscopic decompression. Knee Surg Sports Traumatol Arthrosc. 2007 Jul;15(7):908-14.
- Byrd JW, Jones KS. Arthroscopic management of femoroacetabular impingement in athletes. Am J Sports Med. 2011 Jul;39 Suppl:7S-13S.
- Ganz R, Parvizi J, Beck M, Leunig M, Nötzli H, Siebenrock KA. Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop Relat Res. 2003 Dec;(417):112-20.
- Beck M, Kalhor M, Leunig M, Ganz R. Hip morphology influences the pattern of damage to the acetabular cartilage: femoroacetabular impingement as a cause of early osteoarthritis of the hip. J Bone Joint Surg Br. 2005 Jul;87(7):1012-8.
- Philippon MJ, Stubbs AJ, Schenker ML, Maxwell RB, Ganz R, Leunig M. Arthroscopic management of femoroacetabular impingement: osteoplasty technique and literature review. Am J Sports Med. 2007 Sep;35(9):1571-80. Epub 2007 Apr 9.
- Parvizi J, Leunig M, Ganz R. Femoroacetabular impingement. J Am Acad Orthop Surg. 2007 Sep;15(9):561-70.
- Schoenecker PL, Clohisy JC, Millis MB, Wenger DR. Surgical management of the problematic hip in adolescent and young adult patients. J Am Acad Orthop Surg. 2011 May;19(5):275-86
- 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 Feb;27(2):252-69.
- Safran MR. The acetabular labrum: anatomic and functional characteristics and rationale for surgical intervention. J Am Acad Orthop Surg. 2010 Jun;18(6):338-45.