- FAI is a clinical syndrome of hip pain, limitation in range of motion and abnormal mechanical contact of the femoral head/neck and the acetabulum
- FAI can play a role in the development of osteoarthritis
- There is a high prevalence of morphologic abnormalities found in asymptomatic individuals
- Characterized by abnormal mechanical contact between the rim of the acetabulum and the upper femur
- Clinical syndrome of hip pain, limitation of movement, and joint damage
- Two types: CAM and pincer
- Prevalence remains unknown
- There is some association between FAI and athletic adolescents
- There is a high prevalence of morphologic abnormalities associated with FAI in asymptomatic individuals
- Insidious onset hip pain, usually localized to the groin
- May be precipitated by activities requiring hip flexion
- Physical examination:
- Painful limitation of hip flexion
- Limited range of motion, especially hip flexion and internal rotation
- Anterior impingement test
- Classic provocative maneuver
- Pain elicited by flexion, adduction, and internal rotation of the affected hip
- Other provocative maneuvers include resisted straight leg raise,
- CAM type:
- Frog lateral, cross table lateral or Dunn lateral views can be used
- Reliability depends on location of deformity and rotation of limb during x-rays
- Pincer type:
- AP radiograph usually demonstrates acetabular-sided over coverage
- Coverage assessed with lateral center edge angle (LCEA)
- Hips with LCEA >40 deg at risk for impingement
- Focal over coverage assessed with crossover sign
- Anterior acetabular wall crosses over posterior acetabular wall on properly oriented AP radiograph
- CAM type:
- Radial reconstructions more accurately assess head-neck junction
- Alpha angle of Notzli: estimates the degree at which the radius of curvature of the femoral head begins to increase (larger angle indicates more aspherical head)
- Intra-articular contrast enhances ability to detect an associated labral tear and chondral injury
- Nonoperative management:
- Usually warranted as an initial step
- Includes physical therapy, anti-inflammatories, and lifestyle modifications
- Surgical management:
- Surgical dislocation:
- Performed through a lateral Gibson approach to the hip
- Trochanteric osteotomy and anterior-based arthrotomy
- Allows for rim resection, labral repair, acetabular chondroplasty, femoral osteochondroplasty
- Complete visualization and access to both acetabulum and femoral head
- Anterior arthrotomy:
- Standard anterior approach
- Can be supplemented with arthroscopy
- Allows for femoral osteochondroplasty, labral debridement, and limited acetabular rim resection
- Treatment of acetabular rim lesions and labral repair are difficult
- Incomplete access to posterior hip joint and acetabular rim
- Typically performed with patient supine or lateral using a combination of peritrochanteric, midanterior, and anterior portals
- Smallest amount of surgical dissection
- Requires advanced arthroscopic skills to address all FAI lesions
- Limited access to posterior regions of the hip joint and acetabular rim
- Surgical dislocation:
- Variable outcomes based on patient-related factors including lifestyle, work and sports demands, patient expectations, and duration of symptoms
- FAI can predispose to later development of arthritis in certain patients
- CAM lesion in isolation is not sufficient to cause clinically significant osteoarthritis
- Insufficient evidence to confirm association between pincer deformity and clinical or radiographic osteoarthritis
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