No intervention will be made to the patients in the control group (n = 30). Patients in the control group will receive standard care and discharge education provided by the hospital. Discharge training consists of verbal information about the postoperative period. The "MMD Scale" will be applied to patients who meet the criteria 1 day before the surgery. Patients with a "BCS Scale" ≥ 89 will be included in the study. Patients will be interviewed face to face and written consent will be obtained. Sociodemographic and descriptive data will be obtained with the "Descriptive Patient Form". Discharge day after surgery (3rd day); Functional status level will be measured with KOOS. 3rd and 6th weeks after surgery; Functional status and self-care ability levels will be measured using the KOOS and Self-Care Power Scale, respectively.

Patients assigned to the intervention group (n=30) will receive "Knee Prosthesis-M" mobile application service for iOS and Android devices, in addition to standard treatment. The "MMD Scale" will first be applied to patients who meet the criteria 1 day before the surgery. Patients with a "BCS Scale" ≥ 89 will be included in the study. Patients will be interviewed face to face and written consent will be obtained. Sociodemographic and descriptive data will be obtained with the "Descriptive Patient Form". The intervention group will also use the "Knee Prosthesis-M" mobile application for 6 weeks, starting from the 1st day of the surgery. Discharge day after surgery (3rd day); The level of functional status will be measured using the KOOS. At the 3rd and 6th weeks after surgery, functional status and self-care skills will be measured using the KOOS and Self-Care Power Scale, respectively.

In the early phase of mobile application development, qualitative interviews will be conducted with patients with total knee arthroplasty (TKA) experience regarding their own surgery experiences. A training booklet for "Knee prosthesis-M" will be created, taking into account the literature and patient feedback. Then, the "Knee prosthesis-M" application design will be completed. One day before surgery; Written consent will be obtained from patients who meet the criteria via an "Informed Consent Form". Patients in the intervention group will access the "Knee Prosthesis-M" application from their smartphones and will be asked to use it actively for 6 weeks, starting from the 1st day of the surgery. Mobile application-supported care will be provided to the patients by sending information, warning and reminder messages to the patients for 6 weeks.

It is a scale used to evaluate symptoms and functional status due to knee injuries and knee osteoarthritis. It has 5 subgroups: pain, other symptoms, functional status in daily living activities, functional status in sports and leisure activities, and knee-related quality of life. It consists of 42 questions that take approximately 10 minutes. A change of 10 points or more on each subscale between 0 and 100 indicates a clinically significant change. It has been reported to have good reliability and validity in patients undergoing joint replacement.

The scale is organized as 35 items. The scale is based on four basic features: active and passive response across situations, motivation, knowledge of health practices, and the individual's own feelings and values. Individuals' answers to the self-care power scale were scored from 0 to 4 and evaluated according to the answers given on a 5-point Likert type scale. The answer "It doesn't describe me at all" was given 0 points, the answer "It doesn't describe me much" was given 1 point, the answer "I have no idea" was given 2 points, the answer "It describes me a little" was given 3 points, the answer "It describes me a lot" was given 4 points. There are 8 negative statements (3, 6, 9, 13, 19, 22, 26, 31) in the scale and the scoring is reversed. The highest score obtained from the scale is 140, and an increase in the score indicates that the individual's self-care power increases.