Femoroacetabular Impingement

Original Editor - Douglas Wix

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Clinically Relevant Anatomy:

The hip (acetabulofemoral joint) is a synovial joint formed by articulation between the femur and acetabulum of the pelvis. The head of the femur is cover by type II collagen (Hyaline cartilage) and proteoglycan. The acetabulum is the concaved portion of the ball and socket joint. The acetabulum has a ring of fibrocartilage called the labrum that deepens the acetabulum and improves stability of the hip joint. The hip joint is very stability because of the congruence of the femoral head and acetabular labrum as well as the five ligaments that surround the joint. The four extracapsular ligaments are the iliofemoral, ischiofemoral, and pubofemoral ligament attached to the bones of the pelvis. The ligamentum teres (intracapsular ligament) is attached to the acetabular notch and the femoral head.
There are a variety of pathoanatomical lesions that may be the cause of hip and groin pain in athletes. Recently femoroacetabular impingement has been recognizes as a possible cause of hip pain. Femoroacetabular impingement can be subdivided into CAM or pincher impingement, although both typically occur together. CAM impingement is characterized by morphological abnormality of the superior-anterior aspect of the femoral head-neck junction. This increase in bone results in impingement of the superior-anterior aspect of the femur with the superior-anterior aspect of the acetabulum. Pincher impingement is characterized by excessive bone growth of the superior-anterior aspect of the acetabulum which results in impingement in the same area as the CAM lesion. Both CAM and pincher impingement typically result in cartilage delamination and labral lesions. Either Cam or pincher impingement can cause significant disability with athletic activities and/or ADL’s.

Clinical Presentation

Clinical Findings:

Clinical exam:
– Restricted range of motion, particularly flexion and internal rotation
– Positive impingement test: for anterior femoroacetabular impingement if forced internal
rotation/adduction in 90 degreea of flexion reproduces pain.
For posterior impingement: painful forced external rotation in full extension.
– Drehmann’s sign: unavoidable passive external rotation while performing hip flexion.

Diagnostic Procedures

The contour of the femoral head-neck junction as a predictor for the risk of anterior impingement. http://www.jbjs.org.uk/cgi/reprint/84-B/4/556 

Outcome Measures

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Management / Interventions

Surgical management for Femoroacetabular Impingment. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1888771/pdf/IowaOrthopJ-25-164.pdf

Key Evidence

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Resources

http://blog.evidenceinmotion.com/evidence/files/Tanzer-ClinOrthopRelRes-2004-HipPainLabralTearOA.pdf

Case Studies

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Recent Related Research (from Pubmed)

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References

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