Patient-related outcomes were originally designed to measure outcomes in clinical studies. They were not developed to predict outcomes, however, different studies showed close association between values achieved preoperatively and postoperative outcomes. The aim of the present trial is to identify patients with satisfactory and unsatisfactory outcomes after joint replacement and to investigate whether there are any potential predicting potential in preoperative results of the patient-related outcomes and if there exist other predicting factors for functional recovery or treatment failure after joint replacement surgery.

Inclusion Criteria:

Patients with primary or secondary hip- and knee osteoarthritis undergoing joint replacement surgery.

Exclusion Criteria:

1. An inability to understand the Polish language,
2. Presence of neuromuscular disease and cognitive impairment,
3. Having a prosthesis in another joint of the ipsilateral or contralateral lower limb placed within 6 months before the current surgery,
4. Having rheumatoid arthritis,
5. Symptoms in several joints (hip, knee or ankle) with expected total joint arthroplasty within 1 year.

Adult population with osteoarthritis of the hip or knee.