femoroacetabular impingement

Femoroacetabular impingement
．Limited hip ROM
．Progression to OA
．classification: cam or pincer type, most common: mixed type

Cam type:
．loss of concavity of proximal femur, femoral head aspherecity
．anterosuperior aspect
．Perthe’s disease, SCFE

Pincer type：
．overcoverage of acetabular rim
．DDH, post periacetabular osteotomy
．retroverted acetabulum

PE:
．Internal rotation < 20 degree on hip flexion at 90 degree
．exclude referred pain (inject bupivacaine into hip joint)

Image for cam type
．cross table lateral view (with hip 10 degree internal rotation)
．Dunn view
．α angle

Image for pincer type
．AP view
．Cross over view (crossing of ant & post wall line), posterior wall view (femoral head center lying lateral to posterior wall), ischial sign(ischial spine projecting into pelvic cavity)
．Coxa profunda

Others:
．CT: good for bone
．MRI: acetabulum rim, labral tears, fibrocystic change

Treatment: considerations
1．Physiologic age of patient’s hip
2．Joint narrowing 1-2 mm
3．The damage of subchondral-labral-cartilage structure
4．Severity of retroverted acetabulum
5．Associated proximal femur deformity

Treatment
1．Open correction with dislocation
2．Arthroscopic debridement w/o dislocation
3．Periacetabular osteotomy

1．Oepn dislocation
．for cam type
．expose head-neck junction, acetabular rim
．most important: preserve blood supply to avoid osteonecrosis
．trochanteric osteotomy, lateral to piriformis fossa
．adverse effect: sicatic nerve neurapraxia, trochanteric nonunion

2．Periacetabular osteotomy
．for retroverted acetabulum with posterior wall sign(+)
．anterior arthrotomy + surgical dislocation
．revision：poor orientation, anterior or posterior impingement