Abstract Background: The effect of intra-articular treatment of hip osteoarthritis with hyaluronic acid in the hip joint is not based on large randomized controlled trials. Hyaluronic acid is a well established treatment for osteoarthritis of the knee.

Methods: Randomized controlled trial with three-armed parallel-group design. The patients meeting the inclusion criteria will be randomized into one of the following groups: infiltration of the hip joint with hyaluronic acid, with corticosteroids or with bupivacaine 0,125%.

Pain VAS, Harris Hip Score and HOOS were scored during follow-up. The patients will be asked to determine their situation as worse, stabile or better then at the time of enrollment. There will be asked if they use painkillers and if they have complications/adverse events. These outcome measure instruments will be used at the time of enrollment in the study prior to any injection, and then again at six weeks, 3 and 6 months after the initial injection. The six-month follow-up period begins for all patients on the date the first injection will be administered.

Inclusion Criteria:

1. an age between 30 and 70years
2. radiographic evidence of OA of the hip (Kellgren-Lawrence grading scale 1-3)
3. chronic pain for at least 3 months prior to study entry (day 0)
4. dissatisfaction with prior attempts at non-operative management including nonsteroidal anti-inflammatory drugs.

Exclusion Criteria:

1. Kellgren and Lawrence grade 4
2. an intra-articular hip injection (with any corticosteroid, hyaluronic acid preparation or other) within the previous three months
3. non compliance to the study procedures and or non completion of the study according to investigator's judgment
4. rapid destructive hip.
5. a history of crystalline arthropathy or inflammatory arthritis, neuropathic arthropathy
6. a current other problem in the affected extremity
7. contra-indications for the use of corticosteroids (gastrointestinal ulcer, severe osteoporosis, psychiatric anamnesis, herpes simplex or zoster (viremic stadium), varicella, 8 weeks before and 2 weeks after immunization, systemic mycosis, poliomyelitic except of bulbar encephalitic form lymphadenitis after BCG-vaccination, parenteral depot medication, closed- and wide-angle glaucoma)
8. allergy or hypersensitivity to any of the study medications or to contrast solutions.