From the point of view of nursing to know exactly the different risk factors for the onset of pressure ulcers is very important as it allows to accurately orient preventive care interventions.

All the variable that could influence the development of pressure ulcer in patients undergoing knee replacement surgery are identified and collected: age, sex, body max index, risk to develop Pressure Ulcer (braden score), treatment to prevent pressure ulcers (typology of the devices used, such as air mattresses with alternating or static pressure, heel drains, frequency of mobilization carried out by both the patient care), management of eventual incontinence (use of diapers, urinary catheter), type of anesthesia, type of analgesia, length of stay, the ASA physical status classification system (ASA score), comorbidity, cancer, use of devices for controlling the position of the operated limb (foam valve), the number of physical therapy sessions actually carried out.

Inclusion Criteria:

• Primary knee joint replacement
• Secondary knee joint replacement

Exclusion Criteria:

• Cancer patients
• Adult or Senior with pressure ulcer at the heel

Patients undergoing knee replacement surgery following chronic joint disease