The aim of this study is to compare the cost-effectiveness of major joint replacement in patients with short and non-fixed (control group) waiting time (WT). After being placed on the waiting list, patients will be randomized into two groups through regular contact with the practice staff: (1) Patients with non-fixed waiting time (patient undergoes hospital's normal procedure from the date (s)he is added to the waiting list to the date of operation), and (2) patients with short waiting time (operated in maximum three months). The main question is: is it possible to improve the cost-effectiveness of major joint replacement by shortening waiting time?

The aim of this study is to compare the cost-effectiveness of major joint replacement in patients with short and non-fixed (control group) waiting time (WT). After being placed on the waiting list, patients will be randomized into two groups through regular contact with the practice staff:

1. Patients with non-fixed waiting time (patient undergoes hospital's normal procedure from the date (s)he is added to the waiting list to the date of operation), and
2. patients with short waiting time (operated in maximum three months).

For ethical reasons, care will be taken to avoid any risk of inequality between the patient groups. Such inequality might result if some patients should wait for access to treatment longer than normally or if short waiting times would accounted for more than half of the hospital's surgical capacity, for instance. The number of patients placed on the waiting list varies from one month to another, being specific to each hospital. Therefore no advance estimate can be made of the number of patients to be placed on the list. Consequently, the following arrangements will be made:

1. the patients randomised into the short WT group could only be operated on every fourth month, and only half of the hospital's one-month surgical capacity could be allocated as short WTs, so the number of short WTs will be restricted and determined specifically for each hospital;
2. it will be ensured that all eligible patients placed on the waiting list have a chance of getting recruited into the study (including the possibility of short WT) by not restricting the size of the non-fixed WT group. In order to avoid selection bias among the patients, the groups will be different in size.
3. Recruitments will be made in periods of three months in order to avoid the waiting time for the short WT group exceeding three months.

Randomization is made by the nurse responsible using consecutively numbered and sealed envelopes. Participants complete a self-administered questionnaire at four specific points in time:

1. when placed on the waiting list by the orthopaedic surgeon (baseline),
2. at hospital admission,
3. three, and
4. 12 months after surgery.

Inclusion Criteria:

• a need for a primary unilateral or bilateral THR (total hip replacement) or TKR (total knee replacement) due to osteoarthritis (OA) evaluated by the orthopaedic surgeon
• aged 16 years or older
• female or male
• patient is placed on the waiting list in a research hospital
• the patent is willing and mentally able to participate in the study.

Exclusion Criteria:

• Subjects with rheumatoid arthritis
• Subjects with fractures
• Subjects with haemophilia
• Subjects with congenital deformities
• Subjects with a need for re-arthroplasty