The diagnostic gold standard to differentiate FAI (femural acetabular impingement) from other
muscular-tendinous pathologies is, actually, the injection of intra-articular anesthetic
(lidocaine), with a pre- and post- evaluation of pain scale.
If, after injection, the pain disappears, the pain is probably due to an articular problem
(FAI). This kind of differential diagnosis test has a sensibility of 100% and a specificity
C-terminal telopeptide of type II collagen (CTXII) as cartilage degradation index, could be a
marker, simply detectable, to assess the healthy of the cartilage status and could be
measured in serum and urine.