The aim of this observational study is to determine content of rare metals and other elements, along with the levels of selected immunological parameters, in the tissue of the hip or knee joint in the course of degenerative diseases. Determining potential disturbances in the levels or functions of these parameters may in the future contribute to improving treatment - for example, through supplementation of deficient metals or modulation at the immunological level. The main question it aims to answer is:

Are selected rare metals, trace elements and other selected immunological parameters lowered in the tissue of the hip or knee joint as well as in serum in the course of osteoarthritis?

Inclusion Criteria:

• 18 years old and more
• patient qualified for primary TKA or primary THA
• patient diagnosed with hip or knee osteoarthritis
• a complete set of tissues of good quality and volume is available
• does not meet the exclusion criteria.

Exclusion Criteria:

• lack of written consent to participate in the study or surgery
• any private or professional relationship with the Investigators
• genetic connective tissue diseases (e.g., Ehlers-Danlos syndrome and others)
• genetic metabolic diseases (e.g., gout and others)
• genetic diseases affecting the anatomy of the operated joint (e.g., dysplasia and others)
• previous surgeries altering the anatomy of the examined joint (e.g., periacetabular osteotomy, unicompartmental endoprosthesis, and others)
• patients undergoing revision after THA/TKA
• autoimmune diseases in the patient's medical history
• traumatic injury to the hip or knee joint
• previous participation in the study.

Patients undergoing primary THA or TKA at the trauma and orthopedics department of the hospital in Ostrów Mazowiecka, as well as at the trauma and orthopedics department in Międzylesie Specialist Hospital in Poland.