LABRAL TEARS

The classic labral injury of cam impingement is a type 1 tear Type I (Junctional) tear • A cleft begins to separate the labrum from its acetabular attachment • The cleft deepens to a tear

• A paralabral cyst may form.

A different pattern of labral injury occurs with rim/pincer impingement called a Type II tear Type II (Intrasubstance) tear • intrasubstance delamination • cystic degeneration

Both types are most commonly involve the anterosuperior portion of the labrum.

Surgical option include osteochondroplasty, labral excision or repair.

Anteroinferior juctional signal often due to normal recess Small sulcus also found in superior labrum Clefts also found posteroinferior labrum Tears seen in 30% of asymptomatic individuals

CARTILAGE

Plain films are used in the initial assessment of FAI.

Cartilage thinner on the acetabular side Cartilage lesions in FAI can be subtle. Loss of joint space is a very late finding and only occurs when significant osteoarthritis has supervened. In the

The earliest changes occure anterolaterally adjacent to the labrum. The lesion is sometimes called the 'Carpet Lesion'.

Cross sectional imaging options include: MR Arthrography with traction CT arthrography with traction T1 T2 mapping T1rho

Plain MRI Even MR arthography struggles to make a diagnosis of the associated cartilage lesion though some features have been described including loss of normal cartilage signal, surface irregularity and clefts.

Sagittal images best for the anterosuperior lesion Patterns of cartilage damage may give clues to the aetiology Cam lesions tend to occur from the junctional area and extend inwards Dysplasia tends to result in central damage extending outwards

The cartilage is most protected in Pincer deformity