The Thomas Test is an orthopedic test for assessing tightness in the hip flexors and quadriceps.
Have your client supine on the table with one knee up and the other knee and thigh off the edge of the table.
If your client’s knee does not go below the edge of the table it may be because of tight hip flexors (psoas and iliacus).
If your client’s knee does not flex so that the calf is hanging perpendicular to the table it can be from tight quadriceps.
Quadriceps Soft Tissue Release