There are several things that may lead to TFL injuries. My first place to look is for the presence of an anteriorly rotated innominate on the affected side.
What this will do is position the TFL as a strong hip flexor AND internal rotator. I will agree with E.C.'s comment of the psoas being a major contributor in that an anteriorly rotated innominated would mean the psoas is in a shortened position (meaning development of MTP's and subsequent weakness).
My treatment would include: correction of the pelvic anomaly, release psoas trigger points, check strength of hips in the transverse and frontal planes (with subsequent development of an appropriate strengthening program of the weak muscle groups). Hope this helps,