**3. Method of treatment**

Patients are referred to our Arthroscopy Unit due to persistence of pain, lack of a clear diagnosis, failure of conservative treatment (physiotherapy, NSAIDs, and psoas ultrasound guided injections) or instability.

In all cases, we complete a diagnostic protocol including a full clinical history, blood tests (FBC, ESR, CRP); imaging tests (X-rays, CT and MRI scans); scintigraphy (Tc, Ga, In labeled leukocytes); and ultrasound-guided psoas injections. In some cases scintigraphy and CT scans are repeated after a period of at least 3 months to rule out implant loosening.

We perform arthroscopic surgery before indicating revision total hip replacement surgery in all cases of persistent pain where the cause of this has not been clearly identified.

Patients fulfil an informed consent form.
