This is a sprain or tear of the hip joint capsule and the surrounding ligaments usually caused by over stretching or moving the hip too far. This may be a single event, or an over use type phenomenon.
You will feel pain deep in the hip joint itself and this may radiate down the front of the thigh.
If you think you have this condition it is well worth getting it checked out by Mr Willis-Owen. You should avoid any aggravating activities with may prolong the problem. It generally will get better on its own but needs a carefully directed rehabilitation regimen.
Treatment involves first confirming the diagnosis and excluding other problems, which may involve x-rays, ultrasound or MRI scans. Options may include activity modification, physiotherapy, and anti-inflammatories, followed by a stretching program to prevent recurrence.