Surgery for treating femoroacetabular impingement (protocol)

In the last few years there has been increasing recognition of the syndrome of femoroacetabular impingement (FAI), sometimes also called hip impingement, which seems to account for a large proportion of previously undiagnosed cases of hip pain and restricted range of motion in young adults (Lavigne 2004). Subtle shape abnormalities of the hip (a ball and socket joint) combine to cause impingement between the femoral neck and head (ball) and anterior rimof the acetabulum(socket),most often in flexion and internal rotation (Lavigne 2004). Three types of deformities have been recognised: 1. Cam type, asphericity of the femoral head and widening of the femoral neck (abnormalities of shape, typically bumps around the ball of the joint); 2. Pincer type, over coverage of the antero-superior acetabularwall, and abnormal version of the femur or acetabulum (irregularities of shape, typically a socket that is too deep or pointing in an abnormal direction); or 3. mixed type, a combination of the two (Ganz 2003). Excess contact forces between the proximal femur and the acetabular rim during the end range of motion of the hip results in soft tissue lesions of the acetabular labrum (the soft cushion around the socket) and the adjacent acetabular cartilage leading to pain and restricted range of movement (Beck 2004). FAI seems to be associated with progressive articular degeneration of the acetabulum, usually starting from the antero-superior rim and extending medially and posteriorly (Beck 2004). The cause of FAI shapemalformations is likely to bemultifactorial, but may include slipped capital femoral epipihysis (SCFE), which is thought to lead to Cam type FAI (Leunig 2000;Mamisch 2009; Millis 2011). However, other authors now suggest that FAI shape malformations are actually part of a hominid evolutionary process (Hogervorst 2011) whereby Cam type morphology, so called cox recta, is an adaptive